WO2023170979A1 - Titanium material - Google Patents

Titanium material Download PDF

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Publication number
WO2023170979A1
WO2023170979A1 PCT/JP2022/011131 JP2022011131W WO2023170979A1 WO 2023170979 A1 WO2023170979 A1 WO 2023170979A1 JP 2022011131 W JP2022011131 W JP 2022011131W WO 2023170979 A1 WO2023170979 A1 WO 2023170979A1
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Prior art keywords
titanium
less
oxide film
concentration
base material
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PCT/JP2022/011131
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French (fr)
Japanese (ja)
Inventor
実菜美 松本
一浩 ▲高▼橋
遼太郎 三好
道郎 金子
昌宏 山本
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日本製鉄株式会社
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Priority to PCT/JP2022/011131 priority Critical patent/WO2023170979A1/en
Priority to TW112108617A priority patent/TW202342776A/en
Publication of WO2023170979A1 publication Critical patent/WO2023170979A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C14/00—Alloys based on titanium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
    • C22F1/18—High-melting or refractory metals or alloys based thereon

Definitions

  • the present invention relates to titanium materials.
  • Titanium materials exhibit extremely high corrosion resistance in atmospheric environments, and are therefore used for building materials such as building roofs and exterior walls. However, titanium materials that have been used for a long period of time may become discolored. Discoloration of titanium materials may pose a problem from a design standpoint. Therefore, titanium materials that suppress discoloration and have excellent discoloration resistance have been proposed.
  • Patent Document 1 discloses that an oxide film with a thickness of 100 ⁇ or less is present on the surface of the substrate, the amount of C in the surface oxide film is 30 atomic % or less, and the carbon content in the surface layer of the substrate under the oxide film is A titanium material or titanium alloy material with excellent discoloration resistance characterized by an amount of 30 atomic % or less is disclosed.
  • Patent Document 2 describes that in an atmospheric environment, the average carbon concentration in the depth range of 100 nm from the surface is 14 at% or less, and the outermost surface has an oxide film with a thickness of 12 to 40 nm. Titanium is disclosed that is resistant to discoloration.
  • Patent Document 3 discloses a titanium material that does not easily cause discoloration and is characterized in that the amount of fluorine in the oxide film on the surface is 7 at% or less.
  • Patent Document 4 states that in order to efficiently produce a titanium or titanium alloy plate with little discoloration under an environment where it is irradiated with light, the amount of carbon in the carbon-enriched layer on the surface layer of the titanium plate after cold rolling is A titanium plate is cold-rolled using a lubricant with a concentration of 150 mg/m2 or less , then annealed in an oxidizing atmosphere, and then descaled by immersion in molten salt and pickling with an aqueous nitric-hydrofluoric acid solution. A method for manufacturing a titanium plate is disclosed.
  • Patent Document 5 discloses that the average carbon concentration in the depth range of 100 nm from the surface is 14 at% or less, the surface has an oxide film with a thickness of 12 nm or more and 30 nm or less, and the arithmetic mean height of the titanium surface ( Titanium or a titanium alloy is disclosed which is characterized by having a Ra) of 0.035 ⁇ m or less and is less likely to discolor in an atmospheric environment.
  • Patent Documents 1 to 5 say that deterioration of the color fastness of titanium material is suppressed by reducing the carbon concentration on the surface. Further, conventional evaluation of the color fastness of titanium materials is, for example, as described in Patent Document 5, based on the color difference after being immersed in sulfuric acid of pH 3 at a temperature of 60° C. for 14 days. However, in recent years, there has been a demand for titanium materials that have even better discoloration resistance than conventional titanium materials.
  • the present invention was made in view of the above problems, and an object of the present invention is to provide a titanium material with excellent discoloration resistance that can suppress discoloration for a longer period of time than conventional titanium materials. It is.
  • the present invention aims to provide a titanium material that does not discolor even when immersed for a longer period of time than the evaluations described in Patent Documents 1 to 5, for example.
  • the gist of the present invention which was completed based on the above findings, is as follows.
  • the titanium material according to one aspect of the present invention has an average of the range from the surface to a position where the oxygen concentration measured in the thickness direction from the surface by glow discharge spectrometry is 1/3 of the maximum value.
  • Nitrogen concentration and average carbon concentration are each 14.0 atom % or less, and the average hydrogen concentration is 30.0 atom % or less,
  • the c-axis lattice constant of ⁇ -phase Ti determined by X-ray diffraction measurement using the parallel beam method with an incident angle of 0.3 degrees on the surface, and ⁇ determined by X-ray diffraction measurement using the concentrated method at the center of the plate thickness.
  • the difference from the c-axis lattice constant of Ti in the phase is 0.015 ⁇ or less.
  • the titanium material described in [1] above may include an oxide film having a thickness of 30.0 nm or less.
  • the titanium material according to [1] or [2] above has a titanium base material and an oxide film disposed on the surface of the titanium base material, and the titanium material according to the above [1] or [2] has a titanium base material and an oxide film disposed on the surface of the titanium base material, and the titanium material according to X-ray photoelectron spectroscopy on the oxide film.
  • the maximum value of the nitrogen concentration derived from the nitride when analyzed is 2.0 to 10.0 at.
  • the nitride-derived material exists within a range of 2 to 10 nm from the surface of the oxide film and exists within a range of 20 nm from the position where the oxygen concentration is 1/2 of the maximum value to the titanium base material side when converted in terms of speed.
  • the concentration of nitrogen is less than the maximum value of the nitrogen concentration derived from the nitride in the oxide film and 7 atomic % or less, and the maximum value of the nitrogen concentration derived from the nitride in the oxide film is lower than the maximum value of the nitrogen concentration derived from the nitride in the oxide film.
  • the concentration of nitrogen derived from nitride may be higher than or equal to the carbon concentration derived from carbide at the position where the nitrogen concentration derived from nitride becomes maximum.
  • the titanium material described in [1] or [2] above has Ra/, which is the ratio of the arithmetic mean roughness Ra to the element length RSm, in the roughness curve in the direction in which the arithmetic mean roughness Ra is maximum.
  • the titanium base material has a RSm of 0.006 to 0.015 and a root mean square slope R ⁇ q of 0.150 to 0.280, the titanium base material has a kurtosis Rku of more than 3, and the titanium The skewness Rsk of the base material may be greater than -0.5.
  • the titanium material according to [3] above has Ra, which is the ratio of the arithmetic mean roughness Ra to the element length RSm, in the roughness curve in the direction in which the arithmetic mean roughness Ra of the titanium base material is maximum.
  • /RSm is 0.006 to 0.015
  • the root mean square slope R ⁇ q is 0.150 to 0.280
  • the kurtosis Rku of the titanium base material is greater than 3
  • the skewness of the titanium base material is Rsk may be greater than ⁇ 0.5.
  • the present invention it is possible to provide a titanium material with excellent discoloration resistance that can suppress discoloration for a longer period of time than conventional titanium materials.
  • FIG. 1 is a schematic enlarged cross-sectional view showing a layered structure of a titanium material according to an embodiment of the present invention. It is a figure which shows an example of the change of the spectrum in the depth direction by X-ray photoelectron spectroscopy of the titanium material based on the same embodiment.
  • FIG. 3 is a diagram showing an example of a change in the depth direction of a spectrum obtained by X-ray photoelectron spectroscopy of a general titanium material. It is a figure which shows an example of the element concentration distribution of the depth direction by X-ray photoelectron spectroscopy of the titanium material based on the same embodiment, and a general titanium material.
  • FIG. 1 is a schematic enlarged cross-sectional view showing a layered structure of a titanium material according to an embodiment of the present invention. It is a figure which shows an example of the change of the spectrum in the depth direction by X-ray photoelectron spectroscopy of the titanium material based on the same embodiment.
  • FIG. 3 is a diagram showing the relationship between the maximum concentration of nitrogen derived from titanium nitride in an oxide film and the color difference ⁇ E * ab before and after a discoloration test. It is a figure which shows the relationship between Ra/RSm which is a ratio of arithmetic mean roughness Ra and average length RSm of a contour curve element, root-mean-square slope R ⁇ q of a roughness curve element, and color fastness. It is a schematic diagram for explaining kurtosis Rku.
  • Titanium materials have a structure in which an oxide film is disposed on the surface of a titanium base material, and the discoloration of titanium materials is thought to be due to an increase in the thickness of the oxide film due to acid rain or the like. Since the carbon concentration near the surface of a titanium material affects the increase in the thickness of the oxide film, the carbon concentration on the surface of conventional titanium materials aimed at improving discoloration resistance is limited. The present inventors conducted studies in order to obtain a titanium material with excellent discoloration resistance that suppresses discoloration for a longer period of time than conventional ones.
  • the present inventors used glow discharge spectroscopy (hereinafter referred to as "GDS") to determine the oxygen concentration, carbon The concentration and nitrogen concentration were measured.
  • GDS glow discharge spectroscopy
  • the titanium material has an oxide film, and the position where the oxygen concentration measured by GDS is 1/3 of the maximum value is located on the titanium base material side near the interface between the oxide film and the titanium base material. I found out that it does.
  • the range from the surface of the titanium material to the position where the oxygen concentration measured in the thickness direction by GDS is 1/3 of the maximum value will be referred to as the surface layer portion of the titanium material.
  • the present inventors immersed the titanium material in an aqueous sulfuric acid solution at pH 3 and 60° C. for 4 weeks, and evaluated the color fastness based on the color difference before and after immersion. Comparing the titanium material with obvious discoloration and the titanium material with almost no discoloration before and after this immersion, it was found that there was a difference in the carbon concentration and nitrogen concentration measured by GDS in the titanium material before immersion. Ta. Specifically, in the case of a titanium material that clearly discolored when immersed in an aqueous sulfuric acid solution at pH 3 and 60°C for 4 weeks, the inside of the oxide film and the oxide film and base material of the titanium material before immersion were It was found that nitrogen and carbon exist near the interface on the base material side from the interface with.
  • the oxide film and the nitrogen present in the vicinity of the interface on the base material side from the interface between the oxide film and the base material affect the discoloration of titanium materials.
  • the oxide film and nitrogen present in its vicinity also act as a starting point for the growth of the oxide film, similar to carbon.
  • the nitrogen concentration in the oxide film and its vicinity also affects the discoloration resistance of titanium materials in the same way as the carbon concentration, and the discoloration resistance is improved by limiting the nitrogen concentration. was gotten. Furthermore, in the range from the surface of the titanium material to the position where the oxygen concentration measured in the thickness direction by GDS is 1/3 of the maximum value, the average nitrogen concentration and the average carbon concentration are each 14.0 at% or less. It has been found that the color fastness of titanium materials is improved compared to conventional methods.
  • the average carbon concentration in the surface layer of the titanium material can be lowered by increasing the annealing temperature or by lengthening the annealing time.
  • the average nitrogen concentration can be lowered by increasing the degree of vacuum during heat treatment.
  • the present inventors focused on the hydrogen concentration in the surface layer of the titanium material and investigated the influence of the hydrogen concentration in the surface layer of the titanium material on the discoloration resistance of the titanium material. As a result, it was found that the discoloration resistance was further improved when the average hydrogen concentration in the surface layer of the titanium material was 30.0 at % or less. Titanium hydride is thermodynamically unstable compared to titanium oxide in atmospheric acid rain environments. If the production of titanium oxide is promoted due to an increase in the hydrogen concentration in the titanium material, the discoloration resistance may decrease. However, if the average hydrogen concentration in the surface layer portion of the titanium material is 30.0 at.
  • the present inventors focused on changes in the crystal structure of Ti on the surface of the titanium material.
  • the present inventors have discovered that a change in the c-axis of ⁇ -phase Ti, which is a close-packed hexagonal system, affects the discoloration resistance of a titanium material.
  • the penetration level of X-rays differs depending on the X-ray diffraction energy, but by performing the above X-ray diffraction measurement on the surface of the titanium material and the center of the thickness of the titanium material, it is possible to detect Ti in each ⁇ phase.
  • the c-axis lattice constant can be measured.
  • the increase in the c-axis lattice constant of ⁇ -phase Ti in the surface layer is defined as follows.
  • the c-axis lattice constant of ⁇ -phase Ti determined by X-ray diffraction measurement using the parallel beam method with an incident angle of 0.3 degrees on the surface of the titanium material and the X-ray diffraction measurement using the concentrated method at the center of the plate thickness.
  • the difference between the c-axis lattice constant of ⁇ -phase Ti and the c-axis lattice constant of ⁇ -phase Ti determined by is referred to as an increase in the c-axis lattice constant of ⁇ -phase Ti in the surface layer.
  • the measurement depth in X-ray diffraction measurement using the parallel beam method with an incident angle of 0.3 degrees does not exactly match the thickness range of the surface layer measured by GDS, but it is approximately the same as the depth of the surface layer measured by GDS.
  • the increase in the c-axis lattice constant of ⁇ -phase Ti can be measured. It is thought that oxygen is involved in the increase in the c-axis lattice constant of ⁇ -phase Ti in the surface layer of the titanium material. When oxygen is dissolved in ⁇ -phase Ti in the surface layer of the titanium material, the c-axis lattice constant becomes large.
  • the c-axis lattice constant of ⁇ -phase Ti existing on the surface of the titanium material is larger than the c-axis lattice constant of ⁇ -phase Ti existing at the center of the thickness, acid rain will cause oxidation with a high defect concentration. It is presumed that titanium is generated, oxide film grows easily, and discoloration resistance deteriorates.
  • the crystal structure of ⁇ -phase Ti in the surface layer of the titanium material is affected by the temperature, time, and degree of vacuum of the heat treatment. By increasing the degree of vacuum in the heat treatment atmosphere, the amount of oxygen dissolved in ⁇ -phase Ti in the surface layer of the titanium material decreases, and the c-axis lattice constant of ⁇ -phase Ti in the surface layer of the titanium material decreases. Increase will be suppressed. Up to this point, new findings obtained through studies by the present inventors have been explained.
  • FIG. 1 is a schematic enlarged cross-sectional view showing the layer structure of the titanium material according to the present embodiment.
  • the titanium material according to the present embodiment has an average nitrogen concentration and an average carbon concentration in a range from the surface to a position where the oxygen concentration measured in the thickness direction from the surface by glow discharge spectroscopy is 1/3 of the maximum value.
  • ⁇ -phase Ti determined by X-ray diffraction measurement using a parallel beam method with a concentration of 14.0 atomic % or less, an average hydrogen concentration of 30.0 atomic % or less, and an incident angle of 0.3 degrees on the surface.
  • the difference between the c-axis lattice constant of the ⁇ -phase Ti and the c-axis lattice constant of ⁇ -phase Ti determined by X-ray diffraction measurement using the focusing method at the center of the plate thickness is 0.015 ⁇ or less.
  • the titanium material 1 is a titanium material in which an oxide film 20 is formed on the surface of a titanium base material 10, as shown in FIG.
  • the titanium material 1 has a titanium base material 10 and an oxide film 20 formed on the surface of the titanium base material 10.
  • the surface layer portion 30 is a region from the surface of the titanium material 1 (in other words, the surface of the oxide film 20) to the position where the oxygen concentration measured by GDS is 1/3 of the maximum value in the thickness direction, Contains a part of the titanium base material 10.
  • the titanium base material 10 of the titanium material 1 is pure titanium, industrially pure titanium, or a titanium alloy.
  • the titanium base material 10 is, for example, pure titanium, industrially pure titanium, or a titanium alloy with a Ti content of 70% by mass or more. Below, these may be collectively referred to as "titanium".
  • the crystal structure of pure titanium is a close-packed hexagonal ⁇ phase and does not include a body-centered cubic structure ⁇ phase.
  • Industrially pure titanium mainly consists of an ⁇ phase, and may also contain a ⁇ phase depending on its chemical composition.
  • the titanium alloy may be an ⁇ -type alloy having only an ⁇ -phase, or an ⁇ + ⁇ -type alloy containing a ⁇ -phase with a body-centered cubic structure.
  • the titanium base material 10 may be, for example, industrial titanium.
  • industrial titanium used for the titanium base material 10 include various industrial titanium plates and strips described in JIS H 4600:2012, and various industrial titanium rods described in JIS H 4650:2016. Can be mentioned.
  • industrially pure titanium of JIS Class 1 for example, JIS H 4600:2012
  • JIS H 4600:2012 with reduced impurities
  • industrially pure titanium of JIS Class 2 to Class 4 can be applied to the titanium base material 10.
  • titanium alloys include JIS types 11 to 23, which contain trace amounts of precious metal elements such as palladium, platinum, and ruthenium, and JIS 60 types, which contain relatively many elements, to improve corrosion resistance. Examples include Ti-6Al-4V alloy, 60E type, 61 type, and 61F type.
  • JIS type 1 or equivalent ASTM Gr Industrially pure titanium specified in 1 or its equivalent material is mainly used.
  • titanium alloys mainly containing ⁇ -phase include highly corrosion-resistant alloys (JIS standard grades 11 to 13, 17, 19 to 22, and ASTM grades 7, 11, 13, 14, 17, 30, Ti-0.5Cu, Ti-1.0Cu, Ti-1.0Cu-0.5Nb , Ti-1.0Cu-1.0Sn-0.35Si-0.25Nb, etc. Mm indicates misch metal.
  • Examples of ⁇ + ⁇ type titanium alloys include Ti-3Al-2.5V, Ti-5Al-1Fe, and Ti-6Al-4V.
  • the titanium base material 10 contains aluminum, such as a Ti-6Al-4V alloy, corrosion resistance may deteriorate and discoloration resistance may be adversely affected. Therefore, when forming the oxide film 20 on the surface of the titanium alloy as the titanium base material 10, the influence of alloy elements on the application is investigated in advance, and the composition and thickness of each layer are adjusted as appropriate depending on the titanium base material 10. It is recommended that you do so.
  • the titanium base material 10 is, for example, mass%, Co: 0% or more and 1.0% or less, Cr: 0% or more and 0.5% or less, Ni: 0% or more and 1.00% or less, Ta: 0% or more and 6.00% or less, Al: 0% or more and 7.0% or less, V: 0% or more and 5.0% or less, S: 0% or more and 0.3% or less, Cu: 0% or more and 1.50% or less, Nb: 0% or more and 0.70% or less, Sn: 0% or more and 1.40% or less, Si: 0% or more and 0.55% or less, Mo: 0% or more and 0.5% or less, W: 0% or more and 0.5% or less, Pd: 0% or more 0.25%, Ru: 0% or more and 0.15% or less, Rh: 0% or more and 0.15% or less, Os: 0% or more and 0.15% or less, Ir: 0% or more and 0.15% or less, Pt: 0% or more and 0.15% or less
  • REM is a rare earth element, specifically Sc, Y, light rare earth elements (La, Ce, Pr, Nd, Pm, Sm, Eu) and heavy rare earth elements (Gd, Tb, Dy, Ho). , Er, Tm, Yb, Lu).
  • the titanium base material 10 is, for example, in mass %, C: 0% or more and 0.10% or less, H: 0% or more and 0.015% or less, O: 0% or more and 0.40% or less, N: 0% or more and 0.05% or less, and Fe: 0% or more and 0.50% or less, It is industrially pure titanium with the remainder consisting of Ti and impurities.
  • the titanium base material 10 is, for example, in mass %, Co: 0% or more and 0.80% or less, Pd: 0% or more and 0.25% or less, Cr: 0% or more and 0.2% or less, Ru: 0% or more and 0.06% or less, Ni: 0% or more and 0.60% or less, Ta: 0% or more and 6.0% or less, N: 0% or more and 0.05% or less, C: 0% or more and 0.08% or less, H: 0% or more and 0.015% or less, O: 0% or more and 0.35% or less, and Fe: 0% or more and 0.30% or less, It is a titanium alloy with the remainder consisting of Ti and impurities.
  • the titanium base material 10 is, for example, in mass %, Al: 2.0% or more and 7.0% or less, V: 1.0% up to 5.0%, S: 0% or more and 0.3% or less, REM: 0% or more and 0.08% or less, N: 0% or more and 0.05% or less, C: 0% or more and 0.10% or less, H: 0% or more and 0.015% or less, O: 0% or more and 0.35% or less, and Fe: 0% or more and 2.5% or less, It is a titanium alloy with the remainder consisting of Ti and impurities.
  • the titanium base material 10 is, for example, in mass %, Cu: 0.3% or more and 1.50% or less, Nb: 0% or more and 0.70% or less, Sn: 0% or more and 1.40% or less, Si: 0% or more and 0.55% or less, N: 0% or more and 0.05% or less, C: 0% or more and 0.10% or less, H: 0% or more and 0.015% or less, O: 0% or more and 0.15% or less, and Fe: 0% or more and 0.10% or less, It is a titanium alloy with the remainder consisting of Ti and impurities.
  • the titanium base material 10 is, for example, in mass %, V: 0% or more and 0.5% or less, Ni: 0% or more and 1.00% or less, Cr: 0% or more and 0.5% or less, Co: 0% or more and 1.0% or less, Mo: 0% or more and 0.5% or less, W: 0% or more and 0.5% or less, Pd: 0% or more and 0.15% or less, Ru: 0% or more and 0.15% or less, Rh: 0% or more and 0.15% or less, Os: 0% or more and 0.15% or less, Ir: 0% or more and 0.15% or less, Pt: 0% or more and 0.15% or less, REM: 0.001% or more and 0.10% or less, N: 0% or more and 0.03% or less, C: 0% or more and 0.18% or less, H: 0% or more and 0.015% or less, O: 0% or more and 0.35% or less, Fe: 0% or more and 0.30% or less, and the
  • the term "impurity” is a concept that includes impurities that are mixed in from raw materials or the manufacturing environment when titanium is industrially manufactured. Examples of impurities include Cl, Na, Mg, Ca, and B.
  • the content of each impurity element is preferably 0.1% by mass or less, and the total amount is preferably 0.4% by mass or less.
  • the titanium base material 10 is usually a plate, strip, tube, wire rod, or a shape obtained by appropriately processing these.
  • the titanium base material 10 may have any shape, for example, a spherical shape or a rectangular parallelepiped shape.
  • the thickness of the oxide film 20 is not particularly limited, but if it exceeds 30.0 nm, the coloring of the titanium material 1 may be affected due to light interference. Therefore, the thickness of the oxide film 20 is preferably 30.0 nm or less.
  • the thickness of the oxide film 20 is more preferably 25.0 nm or less, and even more preferably 20.0 nm or less, from the viewpoint of suppressing color development due to light interference.
  • the thickness of the oxide film 20 is more than 0 nm, but may be, for example, 10.0 nm or more.
  • the color fastness of the titanium material is improved by ensuring the thickness of the oxide film 20. Therefore, from the viewpoint of improving color fastness, the thickness of the oxide film 20 on the surface of the titanium material 1 is more preferably 12.0 nm or more.
  • the thickness of the oxide film 20 is measured by GDS. Measurement by GDS is performed in the following manner. GDS measurements are performed using JOBIN YVON GD-Profiler 2 manufactured by Horiba Ltd. in a constant power mode of 35 W, with an argon gas pressure of 600 Pa and a discharge range of 4 mm in diameter. The measurement pitch in GDS measurement is 0.5 nm. In the GDS measurement, O (oxygen), N (nitrogen), C (carbon), H (hydrogen), and Ti are analyzed from the surface of the titanium material 1. The concentration (atomic %) of each of the above elements is calculated with the total of the above elements as 100 atomic %. The thickness of the oxide film 20 is determined from the oxygen concentration measured by GDS.
  • the distance in the thickness direction from the surface to the position where the oxygen concentration is half of the maximum value is the thickness of the oxide film 20.
  • the average nitrogen concentration, average carbon concentration, and average hydrogen concentration are the arithmetic average values of the nitrogen concentration, carbon concentration, and hydrogen concentration values at each measurement point.
  • the concentration of nitrogen derived from nitride near the interface with the oxide film 20 in the titanium base material 10 is preferably less than the maximum value of the nitrogen concentration in the oxide film 20 measured by XPS and 7 atomic % or less.
  • Nitride is formed in the oxide film 20 by the method for manufacturing the titanium material 1 according to the present embodiment, which will be described later. is non-existent or in very small amounts.
  • the nitrogen content of the base material, which is the titanium base material 10 is about 0.05 to 0.07% by mass, and at most about 0.20 atomic%, which is at the impurity level, according to the value obtained by chemical analysis. Since this content is below the solid solubility limit of nitrogen in titanium, no nitride is formed.
  • the concentration of nitrogen derived from nitride near the interface with the oxide film 20 in the titanium base material 10 is preferably less than the maximum value of the nitrogen concentration in the oxide film 20 measured by XPS and 7 atomic % or less.
  • the titanium material 1 is The growth of an oxide film when exposed to an acid rain environment is suppressed, and discoloration is suppressed.
  • the concentration of nitrogen derived from nitride near the interface with the oxide film 20 in the titanium base material 10 is more preferably less than the maximum value of the nitrogen concentration in the oxide film 20 and 3.0 atomic % or less.
  • the lower limit of the nitrogen concentration derived from nitride near the interface with the oxide film 20 in the titanium base material 10 is not limited.
  • the lower limit of the concentration of nitrogen derived from nitrides near the interface with the oxide film 20 in the titanium base material 10 is 0 at.
  • the amount may be about 0.5 at.%.
  • the vicinity of the interface between the titanium base material 10 and the oxide film 20 refers to a range of 20 nm from the interface to the titanium base material side when measured by XPS.
  • a diagram for example, FIG. 4 measured by XPS, which will be described later
  • the position where the oxygen concentration measured by XPS is 1/2 of the maximum value is defined as the interface. Therefore, a 20 nm range from the position where the oxygen concentration measured by XPS becomes 1/2 of the maximum value to the titanium base material side is defined as the vicinity of the interface with the oxide film 21 in the titanium base material 10.
  • the vicinity of the interface with the oxide film 20 in the titanium base material 10 is a region different from the surface layer portion 30.
  • the oxide film 20 can be identified by GDS or XPS, but the thickness of the oxide film obtained by each measurement method often does not exactly match because the measurement methods are different. However, in each measurement method, the definition of an oxide film is the same in that the position where the oxygen concentration is 1/2 of the maximum value is defined as an oxide film. In this application, when measuring the nitrogen concentration derived from nitride near the interface with the oxide film 20 in the titanium base material 10, the oxide film is measured by XPS.
  • the oxide film 20 contains nitrogen derived from nitride. Nitrogen derived from nitride in the oxide film 20 is measured by X-ray Photoelectron Spectroscopy (XPS).
  • FIG. 2 is a diagram showing an example of a change in the spectrum in the depth direction by X-ray photoelectron spectroscopy of the titanium material 1 according to the present embodiment.
  • FIG. 3 is a diagram showing an example of a change in the spectrum in the depth direction of a general titanium material by X-ray photoelectron spectroscopy.
  • FIGS. 2(D) and 3(D) show changes in the Ti2p spectrum in the depth direction.
  • FIG. 2C in the titanium material 1 according to this embodiment, a clear peak derived from nitrides may be observed at a depth corresponding to the oxide film 20.
  • FIG. 3(C) in general titanium materials, the peak derived from nitrides is extremely small.
  • the titanium material 1 according to the present embodiment contains a predetermined amount of nitrogen derived from nitride in the oxide film 20.
  • nitrogen derived from nitride in the oxide film 20 will be explained in detail.
  • the intensity of the peak related to TiN in FIG. 2(A) also increases. Since the nitride in FIG. 2(C) increases, it is considered that the nitride in FIG. 2(C) is derived from titanium nitride.
  • the nitrogen content (maximum value of nitrogen concentration) derived from nitride in the oxide film 20 is preferably 2.0 to 10.0 at.%.
  • the nitride-derived nitrogen content in the oxide film 20 refers to the maximum concentration of nitride-derived nitrogen in the oxide film 20 measured by XPS.
  • the oxide film 20 contains 2.0 atomic % or more of nitrogen derived from nitride using a non-coloring material, the discoloration resistance is further improved. The reason for this is not necessarily clear, but when nitride exists in the oxide film 20, the atomic arrangement is disturbed and the strain distribution in the oxide film 20 changes, or the conductivity changes and the potential reaches a nanometer level.
  • the function of blocking ion transmission (shielding function) in the oxide film 20 has changed due to a change in distribution or the like.
  • the nitrogen content derived from nitride in the oxide film 20 is 2.0 atomic % or more, the shielding function can be improved more reliably, and the effect of improving color fastness can be more reliably obtained.
  • the nitrogen content derived from nitride in the oxide film 20 is more preferably 4.0 atomic % or more in consideration of manufacturing stability.
  • the nitrogen content derived from nitride in the oxide film 20 exceeds 10.0 atomic %, the shielding function may deteriorate and the effect of improving color fastness may not be obtained.
  • the nitrogen content derived from nitrogen is 10.0 at % or less, the shielding function is maintained and a higher effect of improving color fastness can be obtained.
  • the nitrogen content derived from nitride in the oxide film 20 is more preferably 8.0 atomic % or less in consideration of manufacturing stability.
  • FIG. 4 is a diagram showing an example of the element concentration distribution in the depth direction of the titanium material 1 according to the present embodiment (example of the present invention) and a general titanium material (example of the prior art) measured by X-ray photoelectron spectroscopy.
  • the sputtering depth on the horizontal axis in FIG. 4 is the depth converted by the SiO 2 sputtering rate.
  • the example of the present invention shown in FIG. 4 is an element concentration distribution for the titanium material according to the present embodiment shown in FIG.
  • the conventional example shown in FIG. 4 is an element concentration distribution for the general titanium material (industrial pure titanium type 1) shown in FIG.
  • the nitrogen concentration derived from nitrides is maximum at a position where the sputtering depth is 2 to 10 nm when converted to the SiO 2 sputtering rate.
  • the nitrogen concentration is extremely low. Therefore, the depth at which the concentration of nitrogen derived from nitride in the oxide film 20 is maximum is preferably 2 to 10 nm when converted to the sputtering rate of SiO 2 .
  • the upper limit of the sputtering depth is preferably 30 nm or more, including the area near the interface with the oxide film 20 described above. Further, it may be changed depending on the thickness of the oxide film 20, and is preferably about three times or more the thickness of the oxide film 20.
  • FIG. 5 is a diagram showing the relationship between the maximum concentration of nitrogen derived from nitride in the oxide film 20 and the color difference ⁇ E * ab before and after the discoloration test.
  • the nitrogen concentration at the depth where the nitrogen concentration derived from nitride in the oxide film 20 is maximum is less than 2.0 at%, the shielding property is not sufficiently increased and the color difference exceeds 8. There was a case.
  • the concentration of nitrogen derived from nitride exceeds 10.0 atomic %, the shielding performance decreases, and the color difference may exceed 8.
  • the color tone may be golden or yellowish. When the color tone becomes golden or yellowish, the color tone changes, so it may not be suitable for applications where the silver color of titanium itself is required. This change in color is presumed to be due to the material color of titanium nitride becoming apparent. Therefore, the nitrogen concentration at the depth where the nitride-derived nitrogen concentration in the oxide film 20 is maximum is 2.0 to 10.0 at.%.
  • the nitrogen concentration at the depth where the nitride-derived nitrogen concentration in the oxide film 20 is maximum is less than the carbide-derived carbon concentration at the same depth, the color difference may exceed 8. there were. As described above, this is also considered to be due to the fact that the strain distribution within the oxide film 20 is affected, the conductivity changes, and the potential distribution at the nanometer level is affected. Therefore, the nitrogen concentration at the depth where the nitride-derived nitrogen concentration in the oxide film 20 is maximum is equal to or higher than the carbide-derived carbon concentration at the position where the nitride-derived nitrogen concentration in the oxide film 20 is maximum. preferable.
  • the concentrations of N, C, O, and Ti derived from nitrides, carbides, and oxides in the titanium base material 10 and the oxide film 20 are calculated by using X-ray photoelectron spectroscopy and Ar ion sputtering on the surface of the titanium material. This can be done with In detail, the analysis conditions are: Ar + and a sputtering rate of 4.3 nm/min. (SiO 2 equivalent value).
  • the SiO 2 equivalent value is a sputtering rate determined under the same measurement conditions using an SiO 2 film whose thickness was measured in advance using an ellipsometer.
  • a peak appearing at a position where the binding energy is approximately 393 to 408 eV is measured as the N1s peak, and N derived from organic matter is separated as approximately 399 to 401 eV, and N derived from nitride is determined to be approximately 397 ⁇ 1 eV.
  • a peak appearing at a position where the binding energy is approximately 280 to 395 eV is measured as a C1s peak, and organic matter-derived C is determined to be approximately 284 to 289 eV, and carbide-derived C is determined to be approximately 281.5 ⁇ 1 eV.
  • a peak appearing at a position where the binding energy is approximately 525 to 540 eV is measured as the O1s peak, and O derived from organic matter is approximately 399 to 401 eV, and O derived from metal oxide is approximately 529.5 to 530.5 eV.
  • a peak appearing at a position with binding energy of 450 to 470 eV is measured as a Ti2p peak.
  • the binding energy of the above-mentioned substances is a general value, and may change depending on the charging of the measurement sample, etc.
  • a method of correction based on the peak position of the C--C bond in C derived from an organic substance can be applied.
  • the concentration of the above elements can be determined by calculating the peak area of each element detected by XPS, including all peaks related to that element (without separating them), and then adding the sensitivity coefficient for each element to this peak area. It is calculated as a percentage. Up to this point, the content of nitrogen derived from nitrides in the oxide film 20 has been described in detail.
  • the color fastness of the titanium material 1 is improved by decreasing the average nitrogen concentration and average carbon concentration of the surface layer portion 30.
  • the average nitrogen concentration and average carbon concentration of the surface layer portion 30 measured from the surface of the titanium material 1 in the thickness direction by GDS using the above method are each 14.0 atomic % or less from the viewpoint of discoloration resistance.
  • the average nitrogen concentration in the surface layer portion 30 of the titanium material 1 is preferably 12.0 atom % or less, more preferably 10.0 atom % or less.
  • the average carbon concentration of the surface layer portion 30 of the titanium material 1 is preferably 13.0 atom % or less, more preferably 12.0 atom % or less, still more preferably 10.0 atom % or less.
  • the average nitrogen concentration in the surface layer portion 30 of the titanium material 1 may be 0 atomic % or more than 1.0 atomic %.
  • the average carbon concentration of the surface layer portion 30 of the titanium material 1 may be 0 atomic % or more than 1.0 atomic %.
  • the color fastness of the titanium material 1 is further improved by reducing the average hydrogen concentration in the surface layer 30.
  • the hydrogen concentration in the surface layer portion 30 of the titanium material 1 is 30.0 atom % or less, preferably 25.0 atom % or less, more preferably 20.0 atom % or less.
  • Titanium is a metal that has a high affinity for hydrogen, and the hydrogen concentration in the surface layer portion 30 may be 10.0 atomic % or more.
  • the crystal structure of ⁇ -phase Ti in the surface layer 30 of the titanium material 1 affects the color fastness. Specifically, when the c-axis lattice constant of ⁇ -phase Ti in the surface layer 30 of the titanium material 1 increases, the color fastness deteriorates.
  • the increase in the c-axis lattice constant of ⁇ -phase Ti in the surface layer 30 of the titanium material 1 is ⁇ determined by X-ray diffraction measurement using the parallel beam method at an incident angle of 0.3 degrees on the surface of the titanium material 1.
  • the increase in the c-axis lattice constant of ⁇ -phase Ti in the surface layer 30 of the titanium material 1 is 0.015 ⁇ or less, preferably 0.010 ⁇ or less, from the viewpoint of discoloration resistance.
  • the increase in the c-axis lattice constant of ⁇ -phase Ti on the surface of the titanium material 1 is preferably as small as possible, and may be 0 ⁇ . If this increment becomes a negative value, the cause is a measurement error, and the increment is considered to be 0 ⁇ .
  • the c-axis lattice constant of ⁇ -phase Ti in the surface layer 30 of the titanium material 1 is determined by X-ray diffraction measurement using the parallel beam method on the surface of the titanium material.
  • a W/Si multilayer mirror was used on the X-ray incident side.
  • the X-ray source load power (tube voltage/tube current) is 5.4 kW (40 kV/135 mA), respectively.
  • the angle of incidence of the X-rays on the sample is 0.3 degrees, and the diffraction angle 2 ⁇ is scanned.
  • a sample cut out from a titanium material into a size of 25 mm (vertical) x 50 mm (horizontal) by machining is used.
  • a beam is irradiated centering on a 12.5 mm (vertical) x 25 mm (horizontal) area of the sample, and measurement is performed on the surface of the sample.
  • the cut sample may have dirt attached to the surface to be measured, so clean it with acetone or ethanol.
  • the crystal structure of ⁇ -phase Ti at the center of the thickness of the titanium material is measured by X-ray diffraction using the concentration method.
  • the sample used to analyze the crystal structure of ⁇ -phase Ti at the center of the thickness of the titanium material is finished by mechanical polishing and electrolytic polishing so that the center of the thickness of the titanium material becomes the measurement surface for X-ray diffraction measurements. .
  • an X-ray diffraction apparatus used for X-ray diffraction measurements using the parallel beam method which includes an X-ray source, a K ⁇ ray removal filter, and an X-ray source.
  • the load power may also be the same as the conditions for the parallel beam method. Since the crystal structure of Ti is uniform at the center of the plate thickness, samples may be prepared from any point in the width of the plate or in the rolling direction. Here, a sample was prepared from the center of the board from about a quarter of the width, and the test was conducted.
  • the c-axis lattice constant of ⁇ -phase Ti on the surface of the titanium material and at the center of the plate thickness is calculated from the diffraction peak of the (0002) plane using software (Expert High Score Plus) manufactured by Spectris Co., Ltd. . Even when the titanium base material is an ⁇ + ⁇ type, the c-axis lattice constant of ⁇ -phase Ti is calculated from the diffraction peak of ⁇ -phase Ti.
  • the arithmetic mean roughness Ra, the average length RSm of the contour curve element, and the root mean square slope R ⁇ q of the roughness curve element can be measured by a method compliant with JIS B 0601:2013. Note that kurtosis Rku and skewness Rsk, which will be described later, can also be measured by a method based on JIS B 0601:2013.
  • the arithmetic mean roughness Ra of this embodiment is the arithmetic mean roughness Ra defined in JIS B 0601:2013, and is the average of the absolute values of the total coordinate values Zj in the reference length.
  • the reference length of the roughness curve is set to be equal to the cutoff wavelength ⁇ c, that is, 0.8 mm.
  • ⁇ c is a filter that defines the boundary between the roughness component and the waviness component.
  • ⁇ s is a filter that defines the boundary between the roughness component and the shorter wavelength component.
  • n is the number of measurement points
  • Zj is the height of the jth measurement point on the roughness curve.
  • the average length RSm of the contour curve element is calculated from the following formula (2).
  • m is the number of measurement points
  • Xsi is the length of the contour curve element at the reference length
  • the root mean square slope R ⁇ q of the roughness curve element is calculated from the following formula (3).
  • N is the number of measurement points.
  • (dZj/dXj) is the local slope at the j-th measurement point in the roughness curve, and is defined by the following equation (4).
  • ⁇ X is the measurement interval.
  • the measurement interval ⁇ X may be determined as follows.
  • the measurement interval ⁇ X is a value set by the surface roughness profile measuring machine, and if numerical data is obtained at N points when measuring the measurement length L, the measurement interval ⁇ X is on average L/( N-1).
  • SURFCOM 1900DX manufactured by Tokyo Seimitsu, software TIMS Ver.
  • ⁇ X becomes 5 mm/25,600 points, which is about 0.195 ⁇ m on average.
  • the root mean square slope R ⁇ q of the roughness curve element is a parameter that defines the slope angle (local slope dZ/dX) of the minute range formed by the surface unevenness with respect to the reference length X of the roughness curve.
  • FIG. 6 is a diagram showing the relationship between Ra/RSm, which is the ratio of the arithmetic mean roughness Ra of the titanium base material to the average length RSm of the contour curve element, the root mean square slope R ⁇ q of the roughness curve element, and color fastness. It is.
  • color fastness can be evaluated by color difference ⁇ E * ab and appearance observation.
  • L * a * b * for evaluating the color difference ⁇ E * ab
  • light is irradiated from a daylight light source provided directly above the titanium plate. Therefore, the actual appearance may differ.
  • a titanium plate with a large R ⁇ q may appear discolored when visually observed under sunlight even if the color difference ⁇ E * ab is small. Therefore, visual observation under sunlight is also important for evaluating color fastness.
  • ⁇ indicates a condition in which the color difference ⁇ E * ab was 5 or less and the proportion of people who said that the discoloration was not noticeable in visual sensory evaluation was 80% or more
  • x indicates the color difference ⁇ E * Conditions are shown in which, although the ab is 5 or less, the proportion of people who said that the discoloration was not noticeable in visual sensory evaluation was less than 80%.
  • this sensory evaluation by visual observation was carried out by arranging the titanium material that had not been subjected to the previous main discoloration acceleration test and the titanium material after the main discoloration acceleration test on a flat plate, and having 10 evaluators examine the titanium material under sunlight under various conditions. We compared the results from different angles to determine whether there were any angles where the discoloration was noticeable. We compared the proportion of people who said their discoloration was not noticeable. Note that this visual observation is performed under conditions that assume the roof and walls of an actual building, and the evaluation assumes that the color tone changes depending on the viewing angle.
  • the titanium material according to the present embodiment has a surface with Ra/RSm, which is the ratio of the arithmetic mean roughness Ra to the average length RSm of the contour curve elements, of 0.006 to 0.015. It has been found that when the roughness curve element has a root mean square slope R ⁇ q of 0.150 to 0.280, the color fastness is excellent even at higher temperatures and in an acidic environment. Such titanium materials have excellent discoloration resistance even under high temperature and acidic environments, and can further suppress discoloration over a long period of time.
  • Ra/RSm is the ratio of the arithmetic mean roughness Ra to the average length RSm of the contour curve elements
  • Ra/RSm When Ra/RSm is less than 0.006, the irregularities on the surface of the titanium base material are small and the intervals between the irregularities are wide.
  • the surface of the titanium material When Ra/RSm is less than 0.006, the surface of the titanium material is relatively smooth, and due to the optical path difference between the light reflected on the surface of the oxide film and the light reflected on the titanium base material surface, In some cases, the color of the light that is enhanced by the light may be recognized. That is, the titanium material may change color. If Ra/RSm is 0.006 to 0.015, the optical path difference between the light reflected on the surface of the oxide film and the light reflected on the surface of the titanium base material becomes small due to the relatively large slope of the titanium material surface.
  • the upper limit of Ra/RSm is preferably 0.015 so that the effects of the present invention can be clearly obtained.
  • Ra/RSm is 0.006 to 0.015 and the root mean square slope R ⁇ q of the roughness curve element is 0.150 to 0.280, the above effects are obtained by superimposing the titanium material. discoloration is further suppressed. Furthermore, even if a titanium material having the above-mentioned surface condition grows an oxide film of several tens of nanometers on its surface, a change in color tone, that is, discoloration, is suppressed. Therefore, for the titanium base material, in the roughness curve in the direction where the arithmetic mean roughness Ra is maximum, Ra/RSm, which is the ratio of the arithmetic mean roughness Ra to the element length RSm, is 0.006 to 0.015.
  • R ⁇ q is preferably 0.150 to 0.280.
  • the lower limit of Ra/RSm is more preferably 0.007.
  • R ⁇ q is more preferably 0.190 or more. When R ⁇ q is 0.190 to 0.0280, the color difference in the discoloration acceleration test becomes 6 or less, and even higher effects can be obtained.
  • Ra/RSm is preferably 0.006 to 0.015 as described above, but the arithmetic mean roughness Ra is 0.700 to 3.0 ⁇ m.
  • the average length RSm of the contour curve elements is more preferably 60 to 300 ⁇ m. Setting the arithmetic mean roughness Ra to 0.700 to 3.0 ⁇ m and setting the average length RSm of the contour curve elements to 60 to 300 ⁇ m can be achieved industrially relatively easily using the manufacturing method described below. can.
  • Kurtosis Rku is an index representing the sharpness of the amplitude distribution curve.
  • FIG. 7 is a diagram for explaining kurtosis Rku. Furthermore, Figure 7 is based on Tsutomu Miyashita, "Surface roughness that I would like to review again," Journal of the Japan Society for Precision Engineering, Japan Society for Precision Engineering, Vol. 73, No. 2, 2007, p. This is a diagram published in 205.
  • the kurtosis Rku represents the fourth root mean of Zj in a dimensionless reference length determined by the fourth power of the root mean square height Rq.
  • Zj is the height of the jth measurement point on the roughness curve.
  • Rq is the root mean square height and is expressed by the following formula (6).
  • Kurtosis Rku is an index indicating the sharpness of the height distribution, and when Kurtosis Rku is 3, the height distribution is a normal distribution as shown in FIG. 7, and when Kurtosis Rku is less than 3, the value becomes small. As the kurtosis Sku increases beyond 3, the surface becomes flat, and as the value of the kurtosis Sku increases beyond 3, sharp peaks and valleys increase on the surface of the titanium material.
  • the kurtosis Rku of the titanium base material is greater than 3.
  • the surface of the titanium base material has sharp irregularities, and on a surface with sharp irregularities, the specular reflection component in which interference colors become apparent in the light reflected on the surface of the titanium base material is further suppressed. It will be done. As a result, even if the oxide film thickness increases, the interference color becomes even less noticeable, and the discoloration of the titanium material is further suppressed.
  • the skewness Rsk is also called the degree of distortion and is an index representing the sharpness of surface irregularities.
  • the skewness Rsk represents the root mean cube of Z(x) at the reference length, which is made dimensionless by the cube of the root mean square height Rq, and is expressed by the following formula (7).
  • N is the number of measurement points
  • Zj is the height of the jth measurement point on the roughness curve.
  • the skewness Rsk when the valley length is greater than the peak length, the skewness Rsk is greater than 0. In other words, when the skewness Rsk is greater than 0, the proportion of concave portions in the average line of the roughness curve is high. That is, the tips of the peaks (convex portions) in the roughness curve are sharply pointed, and the ends of the valleys (concave portions) are wide.
  • the average line of the roughness curve refers to a curve representing the long wavelength component cut off by the cutoff wavelength ⁇ c.
  • the valley length is smaller than the peak length, the skewness Rsk is smaller than zero.
  • the skewness Rsk when the skewness Rsk is smaller than 0, the proportion of concave portions in the average line of the roughness curve is high. That is, the tips of the peaks (convex portions) in the roughness curve are wide, and the ends of the valleys (concave portions) are sharply pointed.
  • the skewness Rsk When the skewness Rsk is 0, the shape of the unevenness in the roughness curve is symmetrical with respect to the average surface.
  • the skewness Rsk of the titanium base material is preferably greater than -0.5.
  • the tips of the peaks (convex parts) in the roughness curve become sharp, and the light reflected on the titanium base material surface becomes more sharp on the side closer to the light source, that is, at the peaks (protrusions). It becomes more easily scattered and discoloration is further suppressed.
  • the area far from the light source, that is, the valley (convex part) is estimated to be less affected than the peak (convex part) because the shadow effect caused by the peak (convex part) makes it difficult to see the interference color that causes discoloration. be done.
  • the thickness of the titanium material according to this embodiment may be, for example, 0.2 mm or more, or 0.3 mm or more. Further, the thickness of the titanium material according to this embodiment is not particularly limited, and may be, for example, 5.0 mm or less, 3.0 mm or less, or 2.0 mm or less.
  • the average nitrogen concentration and the average carbon concentration in the range from the surface to the position where the oxygen concentration measured in the thickness direction from the surface by glow discharge spectrometry is 1/3 of the maximum value.
  • ⁇ -phase Ti determined by X-ray diffraction measurement using a parallel beam method with a concentration of 14.0 atomic % or less, an average hydrogen concentration of 30.0 atomic % or less, and an incident angle of 0.3 degrees on the surface.
  • the difference between the c-axis lattice constant of the ⁇ -phase Ti and the c-axis lattice constant of ⁇ -phase Ti determined by X-ray diffraction measurement using the focusing method at the center of the plate thickness is 0.015 ⁇ or less.
  • the maximum value of the nitrogen concentration derived from nitrides when analyzed by X-ray photoelectron spectroscopy in the oxide film is 2.0 to 10.0 at%, and the maximum value of the nitrogen concentration derived from the nitrides in the oxide film is 2.0 to 10.0 at%.
  • the nitride is present in a range of 2 to 10 nm from the surface of the oxide film, and the nitride is present in the vicinity of the interface with the oxide film in the titanium base material, when converted to the SiO 2 sputtering rate.
  • the concentration of nitrogen derived from the nitride in the oxide film is less than the maximum value of the nitrogen concentration derived from the nitride and 7.0 atomic % or less, and the maximum value of the nitrogen concentration derived from the nitride in the oxide film is If the concentration of nitrogen derived from the nitride in the oxide film is equal to or higher than the carbon concentration derived from the carbide at the maximum position, the color fastness is excellent even under high temperature and acidic environments. Titanium material, which has excellent discoloration resistance even under high temperature and acidic environments, can further suppress discoloration over a long period of time.
  • Method for manufacturing titanium material An example of a method for manufacturing a titanium material according to this embodiment will be described.
  • the titanium material according to this embodiment is not limited to that manufactured by the manufacturing method described below.
  • pure titanium and titanium alloys used for building materials such as exterior materials are often plate-shaped, an example of a method for producing plate-shaped titanium materials will be described below.
  • a titanium material is manufactured by cold rolling a raw material of pure titanium or a titanium alloy, and then subjecting it to an annealing treatment and a cooling treatment.
  • the titanium material to be subjected to cold rolling may be produced by a known method. For example, using sponge titanium or a master alloy for adding alloying elements as a raw material, a pure material containing the above components is produced by various melting methods such as vacuum arc melting, electron beam melting, or Haas melting such as plasma melting. A titanium or titanium alloy ingot is produced. Next, the obtained ingot is bloomed and hot forged to form a slab, if necessary. Thereafter, the slab is hot rolled into a hot rolled coil of pure titanium or titanium alloy having the above composition. Note that the slab may be subjected to pretreatment such as cleaning treatment and cutting as necessary. Further, when the rectangular shape can be hot rolled by the hearth melting method, hot rolling may be performed without performing hot forging or the like.
  • the hot rolled coil is subjected to cold rolling.
  • Lubricating oil is used in cold rolling, but the lubricating oil used may cause an increase in the carbon concentration on the surface of the titanium material during annealing. Therefore, before annealing, oil present on the surface of the titanium material is preferably removed by alkaline degreasing, dull rolling using dull rolls, coil grinder, polishing, or the like. Note that when lubricating oil is applied to the surface of a titanium material and cold rolling is performed, carbon is contained on the surface of the titanium material due to a mechanochemical reaction.
  • the cold titanium material to be subjected to the final annealing treatment may be pickled or annealed as appropriate.
  • a final annealing treatment is performed on the titanium material after cold rolling or the titanium material after oil removal treatment.
  • the final annealing treatment is generally a process of reducing the strain introduced into the titanium material, pure titanium or titanium alloy, by cold rolling and softening the titanium material.
  • the final annealing treatment and the subsequent cooling treatment include the average nitrogen concentration, average carbon concentration, and average hydrogen concentration in the surface layer of the titanium material, and the ⁇ -phase Ti in the surface layer of the titanium material. This process aims to control the c-axis lattice constant and the thickness of the oxide film.
  • the final sintering treatment is performed in an inert gas (excluding nitrogen gas) atmosphere after creating a vacuum atmosphere, or directly in a vacuum.
  • the inert gas refers to a gas that is inert to titanium, and includes argon, helium, and neon.
  • the heating temperature (annealing temperature) of the final annealing treatment is 630° C. or higher from the viewpoint of reducing the average nitrogen concentration and average carbon concentration in the surface layer portion of the titanium material.
  • the annealing temperature is preferably 650° C. or higher from the viewpoint of reducing the average carbon concentration in the surface layer of the titanium material. Although there is no particular upper limit to the annealing temperature, it is preferably 750° C. or lower from the viewpoint of manufacturing costs.
  • the annealing temperature referred to here is the temperature inside the heating furnace used for annealing treatment, and is measured using a thermocouple installed in the heating furnace.
  • the annealing time is preferably 5 hours or more from the viewpoint of reducing the average nitrogen concentration and average carbon concentration in the surface layer portion of the titanium material.
  • the annealing time is more preferably 10 hours or more.
  • the annealing time may be 3 hours or more because the as-cold rolled titanium material can be annealed.
  • the annealing time is preferably 48 hours or less.
  • the annealing time is preferably 10 hours or less.
  • the annealing time referred to here is the time during which the temperature in the heating furnace containing the titanium material is maintained at the annealing temperature.
  • the final annealing treatment is performed in a vacuum atmosphere, an inert gas atmosphere (excluding nitrogen gas), or an inert gas atmosphere in which an inert gas excluding nitrogen is introduced after creating a vacuum atmosphere.
  • the degree of vacuum of the vacuum atmosphere is, for example, 1.0 ⁇ 10 ⁇ 2 Pa or less.
  • the inert gas atmosphere is preferably a rare gas atmosphere, more preferably an Ar atmosphere.
  • the degree of vacuum before creating an inert gas atmosphere in the final annealing treatment is to suppress the increase in the c-axis lattice constant of ⁇ -phase Ti in the surface layer of the titanium material, and to suppress the average hydrogen concentration and average nitrogen concentration in the surface layer of the titanium material.
  • the inert gas atmosphere in the heating furnace may be, for example, an atmosphere containing 99.99% by volume or more of Ar.
  • the inert atmosphere may be an atmosphere containing 99.99% by volume or more of He (helium).
  • the inside of the heating furnace may be made into a vacuum atmosphere before the start of heating for the final annealing treatment, and then an inert gas atmosphere may be created. In the meantime, the inside of the heating furnace may be changed from a vacuum atmosphere to an inert gas atmosphere.
  • titanium materials can be At the surface, conditions with low levels of oxygen, nitrogen, carbon, and hydrogen are formed.
  • the surface of the titanium material By making the surface of the titanium material highly clean in the final annealing treatment, it can be exposed to the atmosphere, a nitrogen gas atmosphere, or an inert gas atmosphere containing 10% or more nitrogen gas during the subsequent cooling treatment.
  • a predetermined amount of nitride can be generated in the oxide film by the nitrogen contained in these atmospheres.
  • the desired nitride cannot be generated in the oxide film.
  • the nitrogen concentration in the annealing atmosphere is an inert gas of 0.005% by volume or less. Note that in general industrial pure gas, nitrogen accounts for less than half of the impurities, so the purity is sufficient as the atmosphere for the annealing process in this embodiment using the above-mentioned inert gas.
  • the atmosphere for the final annealing treatment is maintained at a temperature below which temper color does not form on the titanium material after the annealing treatment, for example, at a temperature below 300°C.
  • the annealing atmosphere may be maintained until it is cooled to room temperature, or the inside of the heating furnace may be opened to the atmosphere at a temperature of 300° C. or lower.
  • the cooling atmosphere is, for example, an atmosphere similar to the annealing atmosphere at the beginning of cooling, and when the temperature in the heating furnace is below 300°C, an atmosphere consisting of nitrogen gas, or a mixture of argon or helium containing 10% by volume or more of nitrogen. Any atmosphere or air may be used.
  • the cooling rate after the final annealing treatment is not particularly limited. However, at a temperature below 300° C. where the temperature is open, in order to keep the amount of nitrogen derived from nitrides present in the oxide film within a predetermined range, it is preferable to use the conditions described below.
  • the cooling rate until opening is preferably 50°C/min or less, more preferably 30°C/min or less. Furthermore, when cooling a large titanium material weighing 1 ton or more, 1° C./min is preferable.
  • nitrogen gas is introduced into the heating furnace or the inside of the heating furnace is opened to the atmosphere, and the inside of the heating furnace is heated to 10 vol. It is preferable to use a nitrogen atmosphere containing % or more of nitrogen.
  • the amount of nitrogen derived from nitrides present in the oxide film varies depending on the temperature and atmosphere as well as the cleanliness of the titanium material surface. This is because the trace amounts of carbon, oxygen, hydrogen, and nitrogen that exist on the surface of the titanium material compete and react on the surface of the titanium material, but the amount of reaction between nitrogen and titanium depends on which reaction occurs preferentially. This is thought to be because the amount of nitrides produced changes accordingly.
  • the temperature when changing the atmosphere is 300° C. or lower, the reaction between titanium and nitrogen will occur sufficiently, and nitrides will not be produced in excess. Therefore, by cooling treatment subsequent to annealing treatment, the maximum concentration of nitrogen derived from nitrides present in the oxide film can be set to 2.0 to 10.0 at.%.
  • the temperature when changing the atmosphere is less than 200° C., the nitrogen content derived from nitrides in the oxide film will be less than 2.0 at %. This is because the reaction between nitrogen and titanium becomes slower at lower temperatures.
  • the above temperature is preferably 250°C or higher, more preferably 280°C or higher.
  • the cooling time until reaching 200° C. is preferably 1.5 hours or more, and more preferably 2.0 hours or more.
  • the maximum concentration of nitrogen derived from nitrides when analyzed by X-ray photoelectron spectroscopy in the oxide film is reduced. value is 2.0 to 10.0 atomic %, and the position where the nitrogen concentration derived from the nitride in the oxide film has the maximum value is the surface of the oxide film when converted by the sputtering rate of SiO 2 It exists in the range of 2 to 10 nm from .
  • the characteristics of the titanium material according to the present embodiment are maintained.
  • the method for manufacturing a titanium material according to the present embodiment includes a polishing step of polishing the surface of the titanium material using abrasive fine powder having a particle size distribution of #320 or less in accordance with JIS R 6001-2:2017, and It is preferable to include a dull rolling step in which the titanium material is rolled down using a rolling roll having an Ra of 0.5 ⁇ m or more so that the total rolling reduction is 0.10% or more.
  • the polishing step is performed before the final annealing treatment, and the dull rolling step is performed after the final annealing treatment.
  • the Ra/RSm of the titanium base material surface becomes 0.006 to 0.015, and the root mean square slope R ⁇ q of the roughness curve element becomes 0.150 to 0.280. .
  • the polishing process and dull rolling process will be explained.
  • the surface of the titanium material is polished using abrasive fine powder having a particle size distribution of #320 or less in accordance with JIS R 6001-2:2017.
  • the means for polishing the surface of the titanium material is not particularly limited, and for example, known means such as a brush roll or a coil grinder can be used.
  • the surface of a plate coil-shaped titanium material is polished by the following method.
  • the titanium material is polished using a coil line polishing machine using a polishing belt with a count of #320 or less, for example, #320, #240, #100, #80, etc.
  • the abrasive fine powder used in the abrasive belt preferably has a count of #100 or less.
  • polishing may be performed multiple times with the same or different grits.
  • the titanium material used in the polishing process may be manufactured by a known method. For example, using sponge titanium or a master alloy for adding alloying elements as a raw material, a pure material containing the above components is produced by various melting methods such as vacuum arc melting, electron beam melting, or Haas melting such as plasma melting. A titanium or titanium alloy ingot is produced. Next, the obtained ingot is bloomed and hot forged to form a slab, if necessary. Thereafter, the slab is hot rolled into a hot rolled coil of pure titanium or titanium alloy having the above composition. This hot-rolled coil may be cold-rolled, and the titanium material after cold-rolling may be subjected to a polishing process.
  • a pure material containing the above components is produced by various melting methods such as vacuum arc melting, electron beam melting, or Haas melting such as plasma melting.
  • a titanium or titanium alloy ingot is produced. Next, the obtained ingot is bloomed and hot forged to form a slab, if necessary. Thereafter, the slab is hot rolled into
  • the cold-rolled titanium material to be subjected to the polishing step may be appropriately annealed.
  • the slab may be subjected to pretreatment such as polishing and cutting as necessary.
  • hot rolling may be performed without performing blooming, hot forging, or the like.
  • Cold rolling conditions are also not particularly limited, and may be carried out under conditions that allow desired thickness, properties, etc. to be obtained as appropriate.
  • the titanium material is rolled down using a rolling work roll (hereinafter referred to as rolling roll) whose surface has an arithmetic mean roughness Ra of 0.5 ⁇ m or more.
  • rolling roll a rolling work roll
  • the total rolling reduction ratio is 0.10% or more
  • more locally inclined unevenness is imparted to the surface of the titanium material.
  • the arithmetic mean roughness Ra of the surface of the roll is too large, the uneven shape provided in advance by the polishing process may change significantly, so the arithmetic mean roughness Ra of the surface of the roll is preferably 2.0 ⁇ m. It is as follows.
  • the surface roughness of the rolling roll can be adjusted by polishing or shot blasting.
  • the total rolling reduction ratio is preferably 0.10% or more in order to provide locally sloped unevenness, and preferably 0.2% or more in view of the stability of the surface build-up over the entire length of the coil.
  • the surface roughness is 1.5% or less so that the surface roughness formed by polishing in the previous step is not crushed by cold rolling and the necessary uneven shape disappears.
  • one pass of cold rolling is sufficient to obtain the surface characteristics of the present invention, two or more passes of cold rolling are necessary to finish the surface as uniformly as possible over the entire length using a long coil. It may be performed multiple times.
  • the total rolling reduction rate is determined in consideration of this point, and in the case of multiple passes, the total rolling reduction rate is determined from the difference between the initial and finished plate thicknesses.
  • Example 1 The titanium materials shown in Table 1 were cold rolled to a thickness of 0.4 mm, and then degreased using an alkali or organic solvent to remove oil on the surface of the titanium materials.
  • JIS Class 1 pure titanium (equivalent to ASTM Gr. 1)
  • JIS Class 2 pure titanium (equivalent to ASTM Gr. 2)
  • JIS Class 3 pure titanium (equivalent to ASTM Gr. 3)
  • JIS 4 are used in accordance with JIS H 4600:2012.
  • Seed pure titanium (equivalent to ASTM Gr.4), JIS class 11 titanium alloy (equivalent to ASTM Gr.11, Ti-0.15Pd), JIS class 21 titanium alloy (equivalent to ASTM Gr.13, Ti-0.5Ni-0.05Ru) , JIS 17 grade titanium alloy (equivalent to ASTM Gr. 7, Ti-0.05Pd), Ti-Ru-Mm, Ti-3Al-2.5V, Ti-5Al-1Fe, and JIS 60 grade titanium alloy (equivalent to ASTM Gr. 5) , Ti-6Al-4V) was used.
  • Mm in Ti-Ru-Mm represents misch metal.
  • each titanium material was annealed under the conditions shown in Table 1.
  • the opening temperature shown in Table 1 is the temperature when the inside of the furnace is opened in the cooling process after holding each annealing time at each annealing temperature.
  • the temperature at this time is the temperature inside the furnace measured using a thermocouple.
  • heating was started in the vacuum atmosphere shown in "Degree of Vacuum" in Table 1, and until the start of cooling, the temperature in the annealing furnace was 99. Ar gas of 99% by volume or more was introduced.
  • each annealing atmosphere is maintained up to the opening temperature shown in Table 1, and when the temperature in the furnace has decreased to the opening temperature.
  • Example 14 and 15 of the present invention heating was started in an Ar atmosphere, and the Ar atmosphere was maintained until the inside of the furnace was opened.
  • Examples 16 to 18 of the present invention heating was started under the vacuum atmosphere shown in "Degree of Vacuum" in Table 1, and the degree of vacuum was maintained until the inside of the furnace was opened.
  • Comparative Example 4 and Comparative Example 5 the titanium materials shown in Table 1 were cold rolled to a thickness of 0.4 mm, degreased using an alkali or organic solvent, etc., and then subjected to no final annealing treatment. , nitric-hydrofluoric acid pickling finish was performed.
  • the average nitrogen concentration, average carbon concentration, and average hydrogen concentration in the surface layer were determined by the following method. Analysis of O, N, C, H, and Ti was performed using GDS. For the measurement, JOBIN YVON GD-Profiler 2 manufactured by Horiba, Ltd. was used. The measurement conditions were a constant power mode of 35 W, an argon gas pressure of 600 Pa, and a discharge range of 4 mm in diameter. In the measurement by GDS, the measurement pitch was 0.5 nm. The concentration (atomic %) of each of the above elements was calculated with the total of the above elements being 100 atomic %.
  • the range from the surface of the titanium material to the position where the oxygen concentration measured in the thickness direction by GDS was 1/3 of the maximum value was defined as the surface layer portion of the titanium material.
  • the average nitrogen concentration, average carbon concentration, and average hydrogen concentration were the arithmetic average values of the nitrogen concentration, carbon concentration, and hydrogen concentration values at each measurement point.
  • the c-axis lattice constant of ⁇ -phase Ti on the surface of the titanium material was determined by X-ray diffraction measurement using the parallel beam method.
  • a W/Si multilayer mirror was used on the X-ray incident side.
  • the X-ray source load power (tube voltage/tube current) was 5.4 kW (40 kV/135 mA), respectively.
  • the incident angle of the X-rays on the sample was 0.3 degrees, and the diffraction angle 2 ⁇ was scanned.
  • a titanium material with a thickness of 0.4 mm was machined and cut into a size of 25 mm (vertical) x 50 mm (horizontal). Measurements were performed by irradiating a beam centered on a position of 25 mm (vertical) x 25 mm (horizontal). Note that the cut sample was cleaned using acetone because there was a possibility that dirt was attached to the surface to be measured.
  • the c-axis lattice constant of ⁇ -phase Ti at the center of the thickness of the titanium material was measured by X-ray diffraction using the concentration method.
  • the sample used to analyze the crystal structure of ⁇ -phase Ti at the center of the thickness of the titanium material is finished by mechanical polishing and electrolytic polishing so that the center of the thickness of the titanium material becomes the measurement surface for X-ray diffraction measurements.
  • Ta For X-ray diffraction measurements using the focused method, the X-ray diffraction device used for X-ray diffraction measurements using the parallel beam method is used, and the X-ray source, K ⁇ ray removal filter, and X-ray source load power are The conditions were also the same as those for the parallel beam method above.
  • the c-axis lattice constant of ⁇ -phase Ti on the surface of the titanium material and at the center of the plate thickness was calculated from the diffraction peak of the (0002) plane.
  • the difference in the c-axis lattice constant of ⁇ -phase Ti on the surface of the titanium material was determined from the difference between the lattice constant calculated on the surface of the titanium material and the lattice constant calculated at the center of the plate thickness.
  • the thickness of the oxide film was determined by the oxygen concentration measured using the above method using GDS. Specifically, the distance in the thickness direction from the surface to the position where the oxygen concentration was half of the maximum value was defined as the thickness of the oxide film.
  • the content of nitrogen derived from nitrides contained in the oxide film was measured by the following method. That is, from the distribution of nitride-derived nitrogen concentration in the depth direction measured by the following method, the maximum value in the oxide film was taken as the content of nitride-derived nitrogen contained in the oxide film.
  • the concentration of nitrogen derived from nitrides was measured by the following method. That is, using XPS, the surface of the titanium material was sputtered with Ar ions to measure the concentration distribution in the depth direction, and the state of each element at each peak position of N1s, C1s, O1s and Ti2p was analyzed, and nitrides, carbides, etc. , the concentrations of N, C, O, and Ti derived from oxides were calculated. The details were calculated using the procedure described above.
  • the analysis conditions for XPS were as follows. Equipment: Quantera SXM manufactured by ULVAC-PHI X-ray source: mono-AlK ⁇ (h ⁇ :1486.6eV) Beam diameter: 200 ⁇ m ⁇ ( ⁇ analysis area) Detection depth: several nm Intake angle: 45° Sputtering conditions: Ar + , sputtering rate 4.3 nm/min. (SiO 2 equivalent value) The SiO 2 equivalent value is a sputtering rate determined under the same measurement conditions using an SiO 2 film whose thickness was measured in advance using an ellipsometer.
  • Each parameter of the surface roughness of the manufactured titanium material was determined according to JIS B 0601: 2013, and was measured under the following conditions.
  • Equipment Surface roughness profile measuring machine (SURFCOM 1900DX manufactured by Tokyo Seimitsu Co., Ltd., analysis software: TiMS Ver. 9.0.3)
  • Measuring head Shape measuring head manufactured by Tokyo Seimitsu Co., Ltd.
  • Each of the manufactured titanium materials was immersed in an aqueous sulfuric acid solution at pH 3 and 60° C. for 4 weeks, the color difference before and after immersion was calculated, and the color fastness was evaluated based on the color difference value.
  • the color difference ⁇ E is 0 or more and 5 or less, the color fastness is extremely good (A), when it is more than 5 and 10 or less, the color fastness is good (B), and when it is more than 10, it is considered poor ( It was determined that C).
  • L*1, a*1, b*1 are the color measurement results before the color change test
  • L*2, a*2, b*2 are the color measurement results after the color change test
  • the color difference measurement was carried out using CR400 manufactured by Konica Minolta Co., Ltd. under the conditions of a measurement area with a diameter of 8 mm and a D65 light source.
  • the average nitrogen concentration and average carbon concentration in the surface layer portion are both 14.0 at% or less, the average hydrogen concentration is 30.0 at% or less, and the surface and plate thickness of the titanium material are
  • the difference in the c-axis lattice constant of Ti in the central ⁇ phase was 0.015 ⁇ or less, the color difference evaluation results were B or higher, and the visual sensory evaluation results were B or higher.
  • the degree of vacuum during the annealing treatment was as low as 1.0 ⁇ 10 ⁇ 1 Pa, so the average nitrogen concentration in the surface layer portion was high. As a result, both the color difference evaluation result and the visual sensory evaluation result of the titanium material of Comparative Example 1 failed.
  • Comparative Example 2 had a low annealing temperature and a high average carbon concentration in the surface layer. As a result, both the color difference evaluation result and the visual sensory evaluation result of the titanium material of Comparative Example 2 failed.
  • the degree of vacuum during the annealing treatment was as low as 8.0 ⁇ 10 -2 Pa, so the oxygen concentration in the surface layer of the titanium material increased, and the c-axis lattice constant of ⁇ -phase Ti in the surface layer decreased. It is presumed that the difference in lattice constants has become larger. As a result, both the color difference evaluation result and the visual sensory evaluation result of the titanium material of Comparative Example 3 failed. In Comparative Examples 4 and 5, the average hydrogen concentration in the surface layer portion was high, and both the color difference evaluation result and the visual sensory evaluation result of the titanium material of Comparative Example 3 failed.
  • the titanium material according to the present embodiment had excellent discoloration resistance for a long period of time even in a pH 3 sulfuric acid aqueous solution simulating severe acid rain.
  • the present invention is particularly effective for applications in outdoor environments such as roof or wall panels, and its industrial value can be said to be extremely high.
  • Example 2 The titanium materials shown in Table 4 were cold rolled to a thickness of 0.4 mm, and then degreased using an alkali or organic solvent to remove oil on the surface of the titanium materials. Thereafter, each titanium material was annealed under the conditions shown in Table 4.
  • the opening temperature shown in Table 4 is the temperature when the inside of the furnace is opened in the cooling process after holding each annealing time at each annealing temperature. The temperature at this time is the temperature inside the furnace measured using a thermocouple.
  • Example 2 The same evaluation as in Example 1 was performed on each manufactured titanium material. The results are shown in Tables 5 and 6.
  • the maximum concentration of nitrogen derived from nitrides when analyzed by X-ray photoelectron spectroscopy in the oxide film was 2.0 to 10.0 at%.
  • the position where the nitrogen concentration derived from nitride in the oxide film shows the maximum value exists in a range of 2 to 10 nm from the surface of the oxide film when converted to the sputtering rate of SiO 2 , and the oxide film on the titanium base material
  • the concentration of nitrogen derived from nitrides existing near the interface with The concentration of nitrogen derived from nitride in the oxide film was higher than the carbon concentration derived from carbide at the maximum position.
  • the color difference evaluation results were A, and the visual sensory evaluation results were all A++, indicating excellent color fastness.
  • Example 3 After cold rolling the titanium materials shown in Table 7 to a thickness of 0.4 mm, a polishing step, cleaning, annealing treatment, and dull rolling step were performed in this order under the conditions shown in Tables 7 and 8.
  • the "number of polishing passes" shown in Table 7 indicates the number of times the titanium material was passed through the line of a coil grinder consisting of three polishing stands on which polishing belts were arranged.
  • each titanium material was subjected to final annealing treatment under the conditions shown in Table 8.
  • the opening temperatures shown in Table 8 are the temperatures when the inside of the furnace was opened in the cooling process after each annealing time was maintained at each annealing temperature.
  • the temperature at this time is the temperature inside the furnace measured using a thermocouple.
  • heating was started under the vacuum atmosphere shown in "Degree of Vacuum" in Table 8, and until the start of cooling, 99.99% by volume or more of Ar was present in the annealing furnace. gas was introduced.
  • each annealing atmosphere is maintained up to the opening temperature shown in Table 8, and when the temperature in the furnace has decreased to the opening temperature. The inside of the furnace was opened.
  • Inventive Example 62 heating was started under the vacuum atmosphere shown in "Degree of Vacuum" in Table 8, and the vacuum degree was maintained until the inside of the furnace was opened.
  • Comparative Example 6 a titanium material was cold rolled to a thickness of 0.4 mm, degreased using an alkali or organic solvent, and then finished by pickling with nitric hydrofluoric acid without performing a final annealing treatment. I was disappointed.
  • Example 9 The same evaluation as in Example 1 was performed on each manufactured titanium material. The results are shown in Tables 9 and 10. The underline in Table 9 indicates that it is outside the scope of the present invention.
  • the arithmetic mean roughness Ra and element length will change in the roughness curve in the direction where the arithmetic mean roughness Ra is maximum.
  • the ratio of RSm, Ra/RSm is 0.006 to 0.015
  • the root mean square slope R ⁇ q is 0.150 to 0.280
  • the kurtosis Rku of the titanium base material is more than 3
  • the titanium base material has a kurtosis Rku of more than 3. It was found that the skewness Rsk of the base material could be made to exceed -0.5, and the evaluation results were even more excellent.
  • both the average nitrogen concentration and the average carbon concentration in the surface layer portion are 14.0 atomic % or less, the average hydrogen concentration is 30.0 atomic % or less, and the surface layer of the titanium material and The difference in the c-axis lattice constant of Ti in the ⁇ phase at the center of the plate thickness is less than 0.015 ⁇ , and the maximum concentration of nitrogen derived from nitrides when analyzed by X-ray photoelectron spectroscopy in the oxide film is 2.0.
  • the position where the nitrogen concentration derived from nitride in the oxide film shows the maximum value exists within a range of 2 to 10 nm from the surface of the oxide film when converted to the sputtering rate of SiO 2
  • the concentration of nitride-derived nitrogen present near the interface with the oxide film in the titanium base material is less than the maximum value of the nitride-derived nitrogen concentration in the oxide film and 7 at% or less, and the nitride in the oxide film
  • the maximum value of the nitrogen concentration derived from the carbide was higher than the carbon concentration derived from the carbide at the position where the nitrogen concentration derived from the nitride in the oxide film was the maximum.
  • the color difference evaluation result was A
  • the visual sensory evaluation result was A+++, indicating that the color fastness was extremely excellent.
  • Titanium material 10 Titanium base material 20 Oxide film 30 Surface layer part

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Abstract

This titanium material is configured such that: in a range from the surface to a position at which the oxygen concentration measured in the thickness direction from the surface by a glow discharge spectroscopic analysis method is 1/3 the maximum value, the average nitrogen concentration and the average carbon concentration are both 14.0 at% or less, and the average hydrogen concentration is 30.0 at% or less; and the difference between the c-axis lattice constant of α-phase Ti as determined by X-ray diffraction measurement by a parallel beam method in which the angle of incidence on the surface is 0.3 degrees and the c-axis lattice constant of α-phase Ti as determined by X-ray diffraction measurement by an intensive method at the plate thickness center is 0.015 Å or less.

Description

チタン材titanium material
　本発明は、チタン材に関する。 The present invention relates to titanium materials.
　チタン材は、大気環境において極めて優れた耐食性を示すことから、建築物の屋根や、外壁のような建材用途に用いられている。しかしながら、長期間に亘って使用されたチタン材は変色する場合がある。チタン材の変色は、意匠性の観点から問題となる場合がある。そのため、従来から、変色が抑制された、耐変色性に優れるチタン材が提案されている。 Titanium materials exhibit extremely high corrosion resistance in atmospheric environments, and are therefore used for building materials such as building roofs and exterior walls. However, titanium materials that have been used for a long period of time may become discolored. Discoloration of titanium materials may pose a problem from a design standpoint. Therefore, titanium materials that suppress discoloration and have excellent discoloration resistance have been proposed.
　例えば、特許文献１には、厚さ１００Å以下の酸化皮膜が素地表面に存在すると共に、該表面酸化皮膜中のＣ量が３０原子％以下であり、且つ前記酸化皮膜下の素地表層部におけるＣ量が３０原子％以下であることを特徴とする耐変色性に優れたチタン材またはチタン合金材が開示されている。 For example, Patent Document 1 discloses that an oxide film with a thickness of 100 Å or less is present on the surface of the substrate, the amount of C in the surface oxide film is 30 atomic % or less, and the carbon content in the surface layer of the substrate under the oxide film is A titanium material or titanium alloy material with excellent discoloration resistance characterized by an amount of 30 atomic % or less is disclosed.
　特許文献２には、表面から１００ｎｍの深さの範囲における平均の炭素濃度が１４ａｔ％以下であり、かつ、最表面に１２～４０ｎｍの厚みの酸化膜を有することを特徴とする大気環境中において変色を生じにくいチタンが開示されている。 Patent Document 2 describes that in an atmospheric environment, the average carbon concentration in the depth range of 100 nm from the surface is 14 at% or less, and the outermost surface has an oxide film with a thickness of 12 to 40 nm. Titanium is disclosed that is resistant to discoloration.
　特許文献３には、表面の酸化皮膜中におけるフッ素量が７ａｔ％以下であることを特徴とする変色を生じにくいチタン材が開示されている。 Patent Document 3 discloses a titanium material that does not easily cause discoloration and is characterized in that the amount of fluorine in the oxide film on the surface is 7 at% or less.
　特許文献４には、光が照射される環境下での変色の少ないチタンまたはチタン合金板を効率的に製造するために、冷間圧延後のチタン板表層の炭素濃化層の炭素量が、１５０ｍｇ／ｍ２以下となる潤滑剤を用いてチタン板を冷間圧延した後、酸化性雰囲気で焼鈍し、次いで溶融塩浸漬処理と硝ふっ酸水溶液による酸洗とにより脱スケールすることを特徴とするチタン板の製造方法が開示されている。 Patent Document 4 states that in order to efficiently produce a titanium or titanium alloy plate with little discoloration under an environment where it is irradiated with light, the amount of carbon in the carbon-enriched layer on the surface layer of the titanium plate after cold rolling is A titanium plate is cold-rolled using a lubricant with a concentration of 150 mg/m2 or less , then annealed in an oxidizing atmosphere, and then descaled by immersion in molten salt and pickling with an aqueous nitric-hydrofluoric acid solution. A method for manufacturing a titanium plate is disclosed.
　特許文献５には、表面から１００ｎｍの深さの範囲における平均の炭素濃度が１４ａｔ％以下であり、表面に１２ｎｍ以上３０ｎｍ以下の厚みの酸化膜を有し、かつチタン表面の算術平均高さ（Ｒａ）が０．０３５μｍ以下であることを特徴とする大気環境中において変色を生じにくいチタンまたはチタン合金が開示されている。 Patent Document 5 discloses that the average carbon concentration in the depth range of 100 nm from the surface is 14 at% or less, the surface has an oxide film with a thickness of 12 nm or more and 30 nm or less, and the arithmetic mean height of the titanium surface ( Titanium or a titanium alloy is disclosed which is characterized by having a Ra) of 0.035 μm or less and is less likely to discolor in an atmospheric environment.
特開２０００－１７２９号公報Japanese Patent Application Publication No. 2000-1729 特開２００２－１２９６２号公報Japanese Patent Application Publication No. 2002-12962 特開２００２－４７５８９号公報Japanese Patent Application Publication No. 2002-47589 特開２００２－６０９８４号公報Japanese Patent Application Publication No. 2002-60984 特開２００５－２７２８７０号公報Japanese Patent Application Publication No. 2005-272870
　特許文献１～５に記載の技術では、表面の炭素濃度の低下によって、チタン材の耐変色性の劣化が抑制されるとしている。また、従来のチタン材の耐変色性の評価は、例えば、特許文献５に記載されているとおり、温度が６０℃であるｐＨ３の硫酸中に１４日間浸漬した後の色差によって評価されている。しかし、近年では、従来のチタン材よりも更に耐変色性に優れるチタン材が求められている。 The techniques described in Patent Documents 1 to 5 say that deterioration of the color fastness of titanium material is suppressed by reducing the carbon concentration on the surface. Further, conventional evaluation of the color fastness of titanium materials is, for example, as described in Patent Document 5, based on the color difference after being immersed in sulfuric acid of pH 3 at a temperature of 60° C. for 14 days. However, in recent years, there has been a demand for titanium materials that have even better discoloration resistance than conventional titanium materials.
　本発明は、上記問題に鑑みなされたものであり、従来のチタン材よりも長期に亘って変色を抑制することが可能な、耐変色性に優れたチタン材を提供することを目的とするものである。本発明は、例えば、特許文献１～５に記載の評価よりも長期間の浸漬を行っても変色が生じないチタン材の提供を目的とする。 The present invention was made in view of the above problems, and an object of the present invention is to provide a titanium material with excellent discoloration resistance that can suppress discoloration for a longer period of time than conventional titanium materials. It is. The present invention aims to provide a titanium material that does not discolor even when immersed for a longer period of time than the evaluations described in Patent Documents 1 to 5, for example.
　上記知見に基づき完成された本発明の要旨は、以下のとおりである。
［１］本発明の一態様に係るチタン材は、表面から、グロー放電分光分析法によって前記表面から厚さ方向に測定された酸素濃度が最大値の１／３である位置までの範囲の平均窒素濃度および平均炭素濃度がそれぞれ１４．０原子％以下、平均水素濃度が３０．０原子％以下であり、
　前記表面において入射角が０．３度である平行ビーム法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数と、板厚中央において集中法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数との差が０．０１５Å以下である。
［２］上記［１］に記載のチタン材は、厚さが３０．０ｎｍ以下の酸化皮膜を備えていてもよい。
［３］上記［１］または［２］に記載のチタン材は、チタン基材と、前記チタン基材の表面に配された酸化皮膜と、を有し、前記酸化皮膜におけるＸ線光電子分光法で分析したときの窒化物由来の窒素濃度の最大値が２．０～１０．０原子％であり、前記酸化皮膜における前記窒化物由来の窒素濃度が最大値を示す位置が、ＳｉＯ２のスパッタリング速度で換算したときに、前記酸化皮膜の表面から２～１０ｎｍの範囲に存在し、酸素濃度が最大値の１／２になる位置からチタン基材側まで２０ｎｍ範囲に存在する前記窒化物由来の窒素の濃度が、前記酸化皮膜における前記窒化物由来の窒素濃度の最大値未満且つ７原子％以下であり、前記酸化皮膜における前記窒化物由来の前記窒素濃度の最大値が、前記酸化皮膜における前記窒化物由来の前記窒素濃度が最大となる位置の炭化物由来の炭素濃度以上であってもよい。
［４］上記［１］または［２］に記載のチタン材は、算術平均粗さＲａが最大となる方向の粗さ曲線において、算術平均粗さＲａと要素長さＲＳｍの比であるＲａ／ＲＳｍが０．００６～０．０１５であり、かつ、二乗平均平方根傾斜ＲΔｑが０．１５０～０．２８０であるチタン基材を備え、前記チタン基材のクルトシスＲｋｕが３超であり、前記チタン基材のスキューネスＲｓｋが－０．５超であってもよい。
［５］上記［３］に記載のチタン材は、前記チタン基材の算術平均粗さＲａが最大となる方向の粗さ曲線において、算術平均粗さＲａと要素長さＲＳｍの比であるＲａ／ＲＳｍが０．００６～０．０１５であり、かつ、二乗平均平方根傾斜ＲΔｑが０．１５０～０．２８０であり、前記チタン基材のクルトシスＲｋｕが３超であり、前記チタン基材のスキューネスＲｓｋが－０．５超であってもよい。 The gist of the present invention, which was completed based on the above findings, is as follows.
[1] The titanium material according to one aspect of the present invention has an average of the range from the surface to a position where the oxygen concentration measured in the thickness direction from the surface by glow discharge spectrometry is 1/3 of the maximum value. Nitrogen concentration and average carbon concentration are each 14.0 atom % or less, and the average hydrogen concentration is 30.0 atom % or less,
The c-axis lattice constant of α-phase Ti determined by X-ray diffraction measurement using the parallel beam method with an incident angle of 0.3 degrees on the surface, and α determined by X-ray diffraction measurement using the concentrated method at the center of the plate thickness. The difference from the c-axis lattice constant of Ti in the phase is 0.015 Å or less.
[2] The titanium material described in [1] above may include an oxide film having a thickness of 30.0 nm or less.
[3] The titanium material according to [1] or [2] above has a titanium base material and an oxide film disposed on the surface of the titanium base material, and the titanium material according to the above [1] or [2] has a titanium base material and an oxide film disposed on the surface of the titanium base material, and the titanium material according to X-ray photoelectron spectroscopy on the oxide film. The maximum value of the nitrogen concentration derived from the nitride when analyzed is 2.0 to 10.0 at. The nitride-derived material exists within a range of 2 to 10 nm from the surface of the oxide film and exists within a range of 20 nm from the position where the oxygen concentration is 1/2 of the maximum value to the titanium base material side when converted in terms of speed. The concentration of nitrogen is less than the maximum value of the nitrogen concentration derived from the nitride in the oxide film and 7 atomic % or less, and the maximum value of the nitrogen concentration derived from the nitride in the oxide film is lower than the maximum value of the nitrogen concentration derived from the nitride in the oxide film. The concentration of nitrogen derived from nitride may be higher than or equal to the carbon concentration derived from carbide at the position where the nitrogen concentration derived from nitride becomes maximum.
[4] The titanium material described in [1] or [2] above has Ra/, which is the ratio of the arithmetic mean roughness Ra to the element length RSm, in the roughness curve in the direction in which the arithmetic mean roughness Ra is maximum. The titanium base material has a RSm of 0.006 to 0.015 and a root mean square slope RΔq of 0.150 to 0.280, the titanium base material has a kurtosis Rku of more than 3, and the titanium The skewness Rsk of the base material may be greater than -0.5.
[5] The titanium material according to [3] above has Ra, which is the ratio of the arithmetic mean roughness Ra to the element length RSm, in the roughness curve in the direction in which the arithmetic mean roughness Ra of the titanium base material is maximum. /RSm is 0.006 to 0.015, the root mean square slope RΔq is 0.150 to 0.280, the kurtosis Rku of the titanium base material is greater than 3, and the skewness of the titanium base material is Rsk may be greater than −0.5.
　本発明によれば、従来のチタン材よりも長期に亘って変色を抑制することが可能な、耐変色性に優れたチタン材の提供することが可能になる。 According to the present invention, it is possible to provide a titanium material with excellent discoloration resistance that can suppress discoloration for a longer period of time than conventional titanium materials.
本発明の一実施形態に係るチタン材の層構成を示す模式的な拡大断面図である。FIG. 1 is a schematic enlarged cross-sectional view showing a layered structure of a titanium material according to an embodiment of the present invention. 同実施形態に係るチタン材のＸ線光電子分光法によるスペクトルの深さ方向の変化の一例を示す図である。It is a figure which shows an example of the change of the spectrum in the depth direction by X-ray photoelectron spectroscopy of the titanium material based on the same embodiment. 一般のチタン材のＸ線光電子分光法によるスペクトルの深さ方向の変化の一例を示す図である。FIG. 3 is a diagram showing an example of a change in the depth direction of a spectrum obtained by X-ray photoelectron spectroscopy of a general titanium material. 同実施形態に係るチタン材および一般のチタン材のＸ線光電子分光法による深さ方向の元素濃度分布の一例を示す図である。It is a figure which shows an example of the element concentration distribution of the depth direction by X-ray photoelectron spectroscopy of the titanium material based on the same embodiment, and a general titanium material. 酸化皮膜内のチタンの窒化物由来の窒素の濃度の最大値と変色試験前後の色差ΔＥ＊ａｂとの関係を示す図である。FIG. 3 is a diagram showing the relationship between the maximum concentration of nitrogen derived from titanium nitride in an oxide film and the color difference ΔE * ab before and after a discoloration test. 算術平均粗さＲａと輪郭曲線要素の平均長さＲＳｍの比であるＲａ／ＲＳｍおよび粗さ曲線要素の二乗平均平方根傾斜ＲΔｑと耐変色性との関係を示す図である。It is a figure which shows the relationship between Ra/RSm which is a ratio of arithmetic mean roughness Ra and average length RSm of a contour curve element, root-mean-square slope RΔq of a roughness curve element, and color fastness. クルトシスＲｋｕを説明するための模式図である。It is a schematic diagram for explaining kurtosis Rku.
　以下、本発明の一実施形態に係るチタン材について、図面を参照しながら説明する。なお、図中の各構成要素の寸法、比率は、実際の各構成要素の寸法、比率を表すものではない。 Hereinafter, a titanium material according to an embodiment of the present invention will be described with reference to the drawings. Note that the dimensions and ratios of each component in the drawings do not represent the actual dimensions and ratios of each component.
　なお、以下に記載する「～」を挟んで記載される数値限定範囲には、下限値および上限値がその範囲に含まれる。「未満」、「超」と示す数値には、その値が数値範囲に含まれない。 Note that the numerically limited ranges described below with "~" in between include the lower limit and the upper limit. Numerical values indicated as "less than" or "greater than" do not include the value within the numerical range.
　まず、本発明を完成するに至った本発明者らの検討により、得られた新たな知見について詳述する。 First, new findings obtained through studies by the inventors that led to the completion of the present invention will be described in detail.
　チタン材は、チタン基材の表面に酸化皮膜が配された構成であり、チタン材の変色は、酸性雨等による酸化皮膜の厚さの増加に起因すると考えられている。チタン材の表面付近の炭素濃度は、酸化皮膜の厚さの増加に影響を及ぼすことから、従来の耐変色性の向上を目的とするチタン材では、その表面の炭素濃度が制限されている。本発明者らは、従来よりも長期に亘って変色が抑制される、耐変色性に優れたチタン材を得るため、検討を行った。 Titanium materials have a structure in which an oxide film is disposed on the surface of a titanium base material, and the discoloration of titanium materials is thought to be due to an increase in the thickness of the oxide film due to acid rain or the like. Since the carbon concentration near the surface of a titanium material affects the increase in the thickness of the oxide film, the carbon concentration on the surface of conventional titanium materials aimed at improving discoloration resistance is limited. The present inventors conducted studies in order to obtain a titanium material with excellent discoloration resistance that suppresses discoloration for a longer period of time than conventional ones.
　まず、本発明者らは、グロー放電分光分析法（Ｇｌｏｗ　Ｄｉｓｃｈａｒｇｅ　Ｓｐｅｃｔｒｏｓｃｏｐｙ、以下、「ＧＤＳ」という。）によって、チタン材の表面（言い換えると、酸化皮膜の表面）から厚さ方向に酸素濃度、炭素濃度、および窒素濃度の測定を行った。チタン材は酸化皮膜を有しており、ＧＤＳによって測定された酸素濃度が最大値の１／３である位置は、酸化皮膜とチタン基材との界面の近傍のチタン基材側の部位に位置することがわかった。以下では、チタン材の表面から、ＧＤＳによって厚さ方向に測定された酸素濃度が最大値の１／３である位置までの範囲をチタン材の表層部と称する。 First, the present inventors used glow discharge spectroscopy (hereinafter referred to as "GDS") to determine the oxygen concentration, carbon The concentration and nitrogen concentration were measured. The titanium material has an oxide film, and the position where the oxygen concentration measured by GDS is 1/3 of the maximum value is located on the titanium base material side near the interface between the oxide film and the titanium base material. I found out that it does. Hereinafter, the range from the surface of the titanium material to the position where the oxygen concentration measured in the thickness direction by GDS is 1/3 of the maximum value will be referred to as the surface layer portion of the titanium material.
　次に、本発明者らは、ｐＨ３、６０℃の硫酸水溶液中にチタン材を４週間浸漬し、浸漬前後の色差に基づいて耐変色性を評価した。この浸漬前後で、明らかに変色が発生したチタン材とほとんど変色しなかったチタン材を比較すると、浸漬前のチタン材にて、ＧＤＳによって測定された炭素濃度および窒素濃度に違いがあることがわかった。具体的には、ｐＨ３、６０℃の硫酸水溶液中に４週間浸漬した際に明らかに変色が発生したチタン材の場合、その浸漬前のチタン材にて、酸化皮膜の内部および酸化皮膜と基材との界面から基材側の界面近傍には、窒素および炭素が存在していることがわかった。従来、酸化皮膜および酸化皮膜と基材との界面から基材側の界面近傍に存在する窒素がチタン材の変色に影響を及ぼすとは考えられていなかった。しかし、チタン材が長期に亘って酸性雨環境に曝された場合、酸化皮膜およびその近傍に存在する窒素も、炭素と同様に起点となって酸化皮膜の成長が生じるものと推察される。 Next, the present inventors immersed the titanium material in an aqueous sulfuric acid solution at pH 3 and 60° C. for 4 weeks, and evaluated the color fastness based on the color difference before and after immersion. Comparing the titanium material with obvious discoloration and the titanium material with almost no discoloration before and after this immersion, it was found that there was a difference in the carbon concentration and nitrogen concentration measured by GDS in the titanium material before immersion. Ta. Specifically, in the case of a titanium material that clearly discolored when immersed in an aqueous sulfuric acid solution at pH 3 and 60°C for 4 weeks, the inside of the oxide film and the oxide film and base material of the titanium material before immersion were It was found that nitrogen and carbon exist near the interface on the base material side from the interface with. Conventionally, it has not been thought that the oxide film and the nitrogen present in the vicinity of the interface on the base material side from the interface between the oxide film and the base material affect the discoloration of titanium materials. However, when a titanium material is exposed to an acid rain environment for a long period of time, it is presumed that the oxide film and nitrogen present in its vicinity also act as a starting point for the growth of the oxide film, similar to carbon.
　また、本発明者らの検討の結果、酸化皮膜およびその近傍の窒素濃度も炭素濃度と同様にチタン材の耐変色性に影響を及ぼし、窒素濃度の制限により、耐変色性が向上するという知見が得られた。更に、チタン材の表面から、ＧＤＳによって厚さ方向に測定された酸素濃度が最大値の１／３である位置までの範囲において、平均窒素濃度および平均炭素濃度がそれぞれ１４．０原子％以下であると、チタン材の耐変色性が従来に比べて向上することがわかった。チタン材の表層部の平均炭素濃度は、焼鈍温度を高くすること、または、焼鈍時間を長くすることによって低下させることができる。平均窒素濃度は、熱処理の真空度を高めることによって低下させることができる。 In addition, as a result of the studies conducted by the present inventors, the nitrogen concentration in the oxide film and its vicinity also affects the discoloration resistance of titanium materials in the same way as the carbon concentration, and the discoloration resistance is improved by limiting the nitrogen concentration. was gotten. Furthermore, in the range from the surface of the titanium material to the position where the oxygen concentration measured in the thickness direction by GDS is 1/3 of the maximum value, the average nitrogen concentration and the average carbon concentration are each 14.0 at% or less. It has been found that the color fastness of titanium materials is improved compared to conventional methods. The average carbon concentration in the surface layer of the titanium material can be lowered by increasing the annealing temperature or by lengthening the annealing time. The average nitrogen concentration can be lowered by increasing the degree of vacuum during heat treatment.
　次に、本発明者らは、チタン材の表層部の水素濃度に着目し、チタン材の表層部の水素濃度によるチタン材の耐変色性への影響について検討を行った。その結果、チタン材の表層部の平均水素濃度が３０．０原子％以下である場合に、耐変色性が更に向上することが見出された。チタンの水素化物は、大気の酸性雨環境では酸化チタンに比べて熱力学的に不安定である。チタン材中の水素濃度の増加によって、酸化チタンの生成が促進されると耐変色性が低下する可能性がある。しかし、チタン材の表層部の平均水素濃度が３０．０原子％以下であれば、水素化チタンが酸化チタンに変化せず、耐変色性の低下が抑制されると考えられる。 Next, the present inventors focused on the hydrogen concentration in the surface layer of the titanium material and investigated the influence of the hydrogen concentration in the surface layer of the titanium material on the discoloration resistance of the titanium material. As a result, it was found that the discoloration resistance was further improved when the average hydrogen concentration in the surface layer of the titanium material was 30.0 at % or less. Titanium hydride is thermodynamically unstable compared to titanium oxide in atmospheric acid rain environments. If the production of titanium oxide is promoted due to an increase in the hydrogen concentration in the titanium material, the discoloration resistance may decrease. However, if the average hydrogen concentration in the surface layer portion of the titanium material is 30.0 at.
　次に、本発明者らは、チタン材の表面のＴｉの結晶構造の変化に着目した。本発明者らは、最密六方晶であるα相のＴｉのｃ軸の変化がチタン材の耐変色性に影響を及ぼすことを見出した。 Next, the present inventors focused on changes in the crystal structure of Ti on the surface of the titanium material. The present inventors have discovered that a change in the c-axis of α-phase Ti, which is a close-packed hexagonal system, affects the discoloration resistance of a titanium material.
　本発明者らの検討により、チタン材の表面において入射角が０．３度である平行ビーム法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数と、板厚中央（厚さ中央ともいう）において集中法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数との差が０．０１５Å以下であれば、耐変色性を大幅に向上させることができることがわかった。上記、Ｘ線回折測定はＸ線回折エネルギーによってＸ線の浸透レベルが異なるが、チタン材の表面とチタン材の板厚中央で上記Ｘ線回折測定を行うことで、それぞれのα相のＴｉのｃ軸の格子定数を測定できる。本願では、表層部のα相のＴｉのｃ軸の格子定数の増加を以下の通り定義する。すなわち、チタン材の表面において入射角が０．３度である平行ビーム法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数と、板厚中央において集中法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数との差を表層部におけるα相のＴｉのｃ軸の格子定数の増加と呼称する。入射角が０．３度である平行ビーム法によるＸ線回折測定での測定深さは、ＧＤＳで測定される表層部の厚さ方向の範囲と厳密には一致しないが、およそ表層部でのα相のＴｉのｃ軸の格子定数の増加を測定できる。
　チタン材の表層部におけるα相のＴｉのｃ軸の格子定数の増加には、酸素が関わっていると考えられる。チタン材の表層部におけるα相のＴｉに酸素が固溶していると、そのｃ軸の格子定数が大きくなる。チタン材の表面に存在するα相のＴｉのｃ軸の格子定数が厚さ中央に存在するα相のＴｉのｃ軸の格子定数よりも大きいと、酸性雨の作用によって、欠陥濃度の高い酸化チタンが生成し、酸化皮膜が成長しやすくなり、耐変色性が劣化すると推察される。チタン材の表層部におけるα相のＴｉの結晶構造には、熱処理の温度、時間、真空度が影響する。熱処理の雰囲気中の真空度を高めることによって、チタン材の表層部におけるα相のＴｉに固溶する酸素の量が減少し、チタン材の表層部におけるα相のＴｉのｃ軸の格子定数の増加が抑制される。ここまで、本発明者らの検討により得られた新たな知見について説明した。 Through studies conducted by the present inventors, the lattice constant of the c-axis of α-phase Ti determined by X-ray diffraction measurement using the parallel beam method with an incident angle of 0.3 degrees on the surface of the titanium material, and the center of the plate thickness (thickness If the difference between the c-axis lattice constant of α-phase Ti and the c-axis lattice constant determined by X-ray diffraction measurement using the focusing method at the center (also called the center) is 0.015 Å or less, the color fastness can be significantly improved. Understood. In the above X-ray diffraction measurement, the penetration level of X-rays differs depending on the X-ray diffraction energy, but by performing the above X-ray diffraction measurement on the surface of the titanium material and the center of the thickness of the titanium material, it is possible to detect Ti in each α phase. The c-axis lattice constant can be measured. In this application, the increase in the c-axis lattice constant of α-phase Ti in the surface layer is defined as follows. In other words, the c-axis lattice constant of α-phase Ti determined by X-ray diffraction measurement using the parallel beam method with an incident angle of 0.3 degrees on the surface of the titanium material, and the X-ray diffraction measurement using the concentrated method at the center of the plate thickness. The difference between the c-axis lattice constant of α-phase Ti and the c-axis lattice constant of α-phase Ti determined by is referred to as an increase in the c-axis lattice constant of α-phase Ti in the surface layer. The measurement depth in X-ray diffraction measurement using the parallel beam method with an incident angle of 0.3 degrees does not exactly match the thickness range of the surface layer measured by GDS, but it is approximately the same as the depth of the surface layer measured by GDS. The increase in the c-axis lattice constant of α-phase Ti can be measured.
It is thought that oxygen is involved in the increase in the c-axis lattice constant of α-phase Ti in the surface layer of the titanium material. When oxygen is dissolved in α-phase Ti in the surface layer of the titanium material, the c-axis lattice constant becomes large. If the c-axis lattice constant of α-phase Ti existing on the surface of the titanium material is larger than the c-axis lattice constant of α-phase Ti existing at the center of the thickness, acid rain will cause oxidation with a high defect concentration. It is presumed that titanium is generated, oxide film grows easily, and discoloration resistance deteriorates. The crystal structure of α-phase Ti in the surface layer of the titanium material is affected by the temperature, time, and degree of vacuum of the heat treatment. By increasing the degree of vacuum in the heat treatment atmosphere, the amount of oxygen dissolved in α-phase Ti in the surface layer of the titanium material decreases, and the c-axis lattice constant of α-phase Ti in the surface layer of the titanium material decreases. Increase will be suppressed. Up to this point, new findings obtained through studies by the present inventors have been explained.
　次に、図１を参照しながら、本発明の一実施形態に係るチタン材について説明する。図１は、本実施形態に係るチタン材の層構成を示す模式的な拡大断面図である。本実施形態に係るチタン材は、表面から、グロー放電分光分析法によって前記表面から厚さ方向に測定された酸素濃度が最大値の１／３である位置までの範囲の平均窒素濃度および平均炭素濃度がそれぞれ１４．０原子％以下、平均水素濃度が３０．０原子％以下であり、前記表面において入射角が０．３度である平行ビーム法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数と、板厚中央において集中法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数との差が０．０１５Å以下である。以下に、本実施形態に係るチタン材を詳細に説明する。 Next, a titanium material according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic enlarged cross-sectional view showing the layer structure of the titanium material according to the present embodiment. The titanium material according to the present embodiment has an average nitrogen concentration and an average carbon concentration in a range from the surface to a position where the oxygen concentration measured in the thickness direction from the surface by glow discharge spectroscopy is 1/3 of the maximum value. α-phase Ti determined by X-ray diffraction measurement using a parallel beam method with a concentration of 14.0 atomic % or less, an average hydrogen concentration of 30.0 atomic % or less, and an incident angle of 0.3 degrees on the surface. The difference between the c-axis lattice constant of the α-phase Ti and the c-axis lattice constant of α-phase Ti determined by X-ray diffraction measurement using the focusing method at the center of the plate thickness is 0.015 Å or less. Below, the titanium material according to this embodiment will be explained in detail.
（チタン材１）
　本実施形態に係るチタン材１は、図１に示すように、チタン基材１０の表面に、酸化皮膜２０が形成されているチタン材である。換言すると、チタン材１は、チタン基材１０と当該チタン基材１０の表面に形成された酸化皮膜２０とを有する。表層部３０は、チタン材１の表面（言い換えると、酸化皮膜２０の表面）から、厚さ方向に、ＧＤＳによって測定される酸素濃度が最大値の１／３である位置までの領域であり、チタン基材１０の一部を含む。 (Titanium material 1)
The titanium material 1 according to this embodiment is a titanium material in which an oxide film 20 is formed on the surface of a titanium base material 10, as shown in FIG. In other words, the titanium material 1 has a titanium base material 10 and an oxide film 20 formed on the surface of the titanium base material 10. The surface layer portion 30 is a region from the surface of the titanium material 1 (in other words, the surface of the oxide film 20) to the position where the oxygen concentration measured by GDS is 1/3 of the maximum value in the thickness direction, Contains a part of the titanium base material 10.
（チタン基材１０）
　チタン材１のチタン基材１０は、純チタン、工業用純チタンまたはチタン合金である。チタン基材１０は、例えば、Ｔｉ含有量が７０質量％以上の純チタン、工業用純チタンまたはチタン合金である。以下では、これらを総称して「チタン」と称する場合がある。純チタンの結晶構造は最密六方晶のα相であり、体心立方構造のβ相を含まない。工業用純チタンは主にα相からなり、化学組成などのよってβ相を含む場合もある。チタン合金は、α相のみのα型合金であってもよく、体心立方構造のβ相を含むα＋β型合金であってもよい。また、チタン基材１０は、例えば、工業用チタンであってもよい。チタン基材１０に用いられる工業用チタンには、例えば、ＪＩＳ　Ｈ　４６００：２０１２に記載された各種工業用チタンの板および条や、ＪＩＳ　Ｈ　４６５０：２０１６に記載される各種工業用チタンの棒が挙げられる。加工性が要求される場合は、不純物を低減したＪＩＳ１種（たとえば、ＪＩＳ　Ｈ　４６００：２０１２）の工業用純チタンが好適である。また、強度が必要とされる場合は、チタン基材１０にＪＩＳ２種～４種の工業用純チタンを適用できる。チタン合金としては、例えば、耐食性を向上させるために、微量の貴金属系の元素、例えば、パラジウム、白金、ルテニウム等を含有するＪＩＳ１１種～２３種や、比較的多くの元素を含むＪＩＳ６０種、例えばＴｉ－６Ａｌ－４Ｖ系合金、６０Ｅ種、６１種、および６１Ｆ種等が挙げられる。なお、建築物では、ＪＩＳ１種やそれと同等であるＡＳＴＭＧｒ．１で規定される工業用純チタンまたはその同等材が主に使用されている。 (Titanium base material 10)
The titanium base material 10 of the titanium material 1 is pure titanium, industrially pure titanium, or a titanium alloy. The titanium base material 10 is, for example, pure titanium, industrially pure titanium, or a titanium alloy with a Ti content of 70% by mass or more. Below, these may be collectively referred to as "titanium". The crystal structure of pure titanium is a close-packed hexagonal α phase and does not include a body-centered cubic structure β phase. Industrially pure titanium mainly consists of an α phase, and may also contain a β phase depending on its chemical composition. The titanium alloy may be an α-type alloy having only an α-phase, or an α+β-type alloy containing a β-phase with a body-centered cubic structure. Further, the titanium base material 10 may be, for example, industrial titanium. Examples of industrial titanium used for the titanium base material 10 include various industrial titanium plates and strips described in JIS H 4600:2012, and various industrial titanium rods described in JIS H 4650:2016. Can be mentioned. If workability is required, industrially pure titanium of JIS Class 1 (for example, JIS H 4600:2012) with reduced impurities is suitable. Furthermore, if strength is required, industrially pure titanium of JIS Class 2 to Class 4 can be applied to the titanium base material 10. Examples of titanium alloys include JIS types 11 to 23, which contain trace amounts of precious metal elements such as palladium, platinum, and ruthenium, and JIS 60 types, which contain relatively many elements, to improve corrosion resistance. Examples include Ti-6Al-4V alloy, 60E type, 61 type, and 61F type. In addition, for buildings, JIS type 1 or equivalent ASTM Gr. Industrially pure titanium specified in 1 or its equivalent material is mainly used.
　α相を主とするチタン合金としては、例えば高耐食性合金（ＪＩＳ規格の１１種～１３種、１７種、１９種～２２種、およびＡＳＴＭ規格のＧｒａｄｅ７、１１、１３、１４、１７、３０、３１で規定されるチタン合金やさらに種々の元素を少量含有させたチタン合金（Ｔｉ－Ｒｕ－Ｍｍなど））、Ｔｉ－０．５Ｃｕ、Ｔｉ－１．０Ｃｕ、Ｔｉ－１．０Ｃｕ－０．５Ｎｂ、Ｔｉ－１．０Ｃｕ－１．０Ｓｎ－０．３５Ｓｉ－０．２５Ｎｂ等がある。Ｍｍは、ミッシュメタルを示す。 Examples of titanium alloys mainly containing α-phase include highly corrosion-resistant alloys (JIS standard grades 11 to 13, 17, 19 to 22, and ASTM grades 7, 11, 13, 14, 17, 30, Ti-0.5Cu, Ti-1.0Cu, Ti-1.0Cu-0.5Nb , Ti-1.0Cu-1.0Sn-0.35Si-0.25Nb, etc. Mm indicates misch metal.
　α＋β型チタン合金としては、例えば、Ｔｉ－３Ａｌ－２．５Ｖ、Ｔｉ－５Ａｌ－１Ｆｅ、Ｔｉ－６Ａｌ－４Ｖ等がある。 Examples of α+β type titanium alloys include Ti-3Al-2.5V, Ti-5Al-1Fe, and Ti-6Al-4V.
　Ｔｉ－６Ａｌ－４Ｖ系合金のように、チタン基材１０がアルミニウムを含有する場合、耐食性が劣化し、耐変色性に悪影響を及ぼす場合がある。そのため、チタン基材１０としてのチタン合金の表面に酸化皮膜２０を形成する場合、予め、用途に対する合金元素の影響を調査し、チタン基材１０に応じて、各層の組成、厚さを適宜調整することが推奨される。 When the titanium base material 10 contains aluminum, such as a Ti-6Al-4V alloy, corrosion resistance may deteriorate and discoloration resistance may be adversely affected. Therefore, when forming the oxide film 20 on the surface of the titanium alloy as the titanium base material 10, the influence of alloy elements on the application is investigated in advance, and the composition and thickness of each layer are adjusted as appropriate depending on the titanium base material 10. It is recommended that you do so.
　チタン基材１０は、例えば、質量％で、
Ｃｏ：０％以上１．０％以下、
Ｃｒ：０％以上０．５％以下、
Ｎｉ：０％以上１．００％以下、
Ｔａ：０％以上６．００％以下、
Ａｌ：０％以上７．０％以下、
Ｖ：０％以上５．０％以下、
Ｓ：０％以上０．３％以下、
Ｃｕ：０％以上１．５０％以下、
Ｎｂ：０％以上０．７０％以下、
Ｓｎ：０％以上１．４０％以下、
Ｓｉ：０％以上０．５５％以下、
Ｍｏ：０％以上０．５％以下、
Ｗ：０％以上０．５％以下、
Ｐｄ：０％以上０．２５％、
Ｒｕ：０％以上０．１５％以下、
Ｒｈ：０％以上０．１５％以下、
Ｏｓ：０％以上０．１５％以下、
Ｉｒ：０％以上０．１５％以下、
Ｐｔ：０％以上０．１５％以下、
ＲＥＭ：０％以上０．１０％以下、
Ｃ：０％以上０．１８％％以下、
Ｈ：０％以上０．０１５％以下、
Ｏ：０％以上０．４０％以下、
Ｎ：０％以上０．０５％以下、および
Ｆｅ：０％以上２．５０％以下を含み、
残部がＴｉおよび不純物からなる、工業用純チタンまたはチタン合金である。
　ここで、ＲＥＭとは希土類元素であり、具体的には、Ｓｃ、Ｙ、軽希土類元素（Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ）及び重希土類元素（Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ）からなる群から選択される一種以上の元素である。 The titanium base material 10 is, for example, mass%,
Co: 0% or more and 1.0% or less,
Cr: 0% or more and 0.5% or less,
Ni: 0% or more and 1.00% or less,
Ta: 0% or more and 6.00% or less,
Al: 0% or more and 7.0% or less,
V: 0% or more and 5.0% or less,
S: 0% or more and 0.3% or less,
Cu: 0% or more and 1.50% or less,
Nb: 0% or more and 0.70% or less,
Sn: 0% or more and 1.40% or less,
Si: 0% or more and 0.55% or less,
Mo: 0% or more and 0.5% or less,
W: 0% or more and 0.5% or less,
Pd: 0% or more 0.25%,
Ru: 0% or more and 0.15% or less,
Rh: 0% or more and 0.15% or less,
Os: 0% or more and 0.15% or less,
Ir: 0% or more and 0.15% or less,
Pt: 0% or more and 0.15% or less,
REM: 0% or more and 0.10% or less,
C: 0% or more and 0.18%% or less,
H: 0% or more and 0.015% or less,
O: 0% or more and 0.40% or less,
N: 0% or more and 0.05% or less, and Fe: 0% or more and 2.50% or less,
It is industrially pure titanium or titanium alloy, with the remainder consisting of Ti and impurities.
Here, REM is a rare earth element, specifically Sc, Y, light rare earth elements (La, Ce, Pr, Nd, Pm, Sm, Eu) and heavy rare earth elements (Gd, Tb, Dy, Ho). , Er, Tm, Yb, Lu).
　また、チタン基材１０は、例えば、質量％で、
Ｃ：０％以上０．１０％以下、
Ｈ：０％以上０．０１５％以下、
Ｏ：０％以上０．４０％以下、
Ｎ：０％以上０．０５％以下、および
Ｆｅ：０％以上０．５０％以下を含み、
残部がＴｉおよび不純物からなる、工業用純チタンである。 Moreover, the titanium base material 10 is, for example, in mass %,
C: 0% or more and 0.10% or less,
H: 0% or more and 0.015% or less,
O: 0% or more and 0.40% or less,
N: 0% or more and 0.05% or less, and Fe: 0% or more and 0.50% or less,
It is industrially pure titanium with the remainder consisting of Ti and impurities.
　また、チタン基材１０は、例えば、質量％で、
Ｃｏ：０％以上０．８０％以下、
Ｐｄ：０％以上０．２５％以下、
Ｃｒ：０％以上０．２％以下、
Ｒｕ：０％以上０．０６％以下、
Ｎｉ：０％以上０．６０％以下、
Ｔａ：０％以上６．０％以下、
Ｎ：０％以上０．０５％以下、
Ｃ：０％以上０．０８％以下、
Ｈ：０％以上０．０１５％以下、
Ｏ：０％以上０．３５％以下、および
Ｆｅ：０％以上０．３０％以下を含み、
残部がＴｉおよび不純物からなる、チタン合金である。 Moreover, the titanium base material 10 is, for example, in mass %,
Co: 0% or more and 0.80% or less,
Pd: 0% or more and 0.25% or less,
Cr: 0% or more and 0.2% or less,
Ru: 0% or more and 0.06% or less,
Ni: 0% or more and 0.60% or less,
Ta: 0% or more and 6.0% or less,
N: 0% or more and 0.05% or less,
C: 0% or more and 0.08% or less,
H: 0% or more and 0.015% or less,
O: 0% or more and 0.35% or less, and Fe: 0% or more and 0.30% or less,
It is a titanium alloy with the remainder consisting of Ti and impurities.
また、チタン基材１０は、例えば、質量％で、
Ａｌ：２．０％以上７．０％以下、
Ｖ：１．０％上５．０％以下、
Ｓ：０％以上０．３％以下、
ＲＥＭ：０％以上０．０８％以下、
Ｎ：０％以上０．０５％以下、
Ｃ：０％以上０．１０％以下、
Ｈ：０％以上０．０１５％以下、
Ｏ：０％以上０．３５％以下、および
Ｆｅ：０％以上２．５％以下を含み、
残部がＴｉおよび不純物からなる、チタン合金である。 Moreover, the titanium base material 10 is, for example, in mass %,
Al: 2.0% or more and 7.0% or less,
V: 1.0% up to 5.0%,
S: 0% or more and 0.3% or less,
REM: 0% or more and 0.08% or less,
N: 0% or more and 0.05% or less,
C: 0% or more and 0.10% or less,
H: 0% or more and 0.015% or less,
O: 0% or more and 0.35% or less, and Fe: 0% or more and 2.5% or less,
It is a titanium alloy with the remainder consisting of Ti and impurities.
　また、チタン基材１０は、例えば、質量％で、
Ｃｕ：０．３％以上１．５０％以下、
Ｎｂ：０％以上０．７０％以下、
Ｓｎ：０％以上１．４０％以下、
Ｓｉ：０％以上０．５５％以下、
Ｎ：０％以上０．０５％以下、
Ｃ：０％以上０．１０％以下、
Ｈ：０％以上０．０１５％以下、
Ｏ：０％以上０．１５％以下、および
Ｆｅ：０％以上０．１０％以下を含み、
残部がＴｉおよび不純物からなる、チタン合金である。 Moreover, the titanium base material 10 is, for example, in mass %,
Cu: 0.3% or more and 1.50% or less,
Nb: 0% or more and 0.70% or less,
Sn: 0% or more and 1.40% or less,
Si: 0% or more and 0.55% or less,
N: 0% or more and 0.05% or less,
C: 0% or more and 0.10% or less,
H: 0% or more and 0.015% or less,
O: 0% or more and 0.15% or less, and Fe: 0% or more and 0.10% or less,
It is a titanium alloy with the remainder consisting of Ti and impurities.
　また、チタン基材１０は、例えば、質量％で、
Ｖ：０％以上０．５％以下、
Ｎｉ：０％以上１．００％以下、
Ｃｒ：０％以上０．５％以下、
Ｃｏ：０％以上１．０％以下、
Ｍｏ：０％以上０．５％以下、
Ｗ：０％以上０．５％以下、
Ｐｄ：０％以上０．１５％以下、
Ｒｕ：０％以上０．１５％以下、
Ｒｈ：０％以上０．１５％以下、
Ｏｓ：０％以上０．１５％以下、
Ｉｒ：０％以上０．１５％以下、
Ｐｔ：０％以上０．１５％以下、
ＲＥＭ：０．００１％以上０．１０％以下、
Ｎ：０％以上０．０３％以下、
Ｃ：０％以上０．１８％以下、
Ｈ：０％以上０．０１５％以下、
Ｏ：０％以上０．３５％以下、
Ｆｅ：０％以上０．３０％以下、および
Ｐｄ、Ｒｕ、Ｒｈ、Ｏｓ、Ｉｒ及びＰｔの合計：０．０１％以上０．１５％以下を含み、
残部がＴｉおよび不純物からなる、チタン合金である。 Moreover, the titanium base material 10 is, for example, in mass %,
V: 0% or more and 0.5% or less,
Ni: 0% or more and 1.00% or less,
Cr: 0% or more and 0.5% or less,
Co: 0% or more and 1.0% or less,
Mo: 0% or more and 0.5% or less,
W: 0% or more and 0.5% or less,
Pd: 0% or more and 0.15% or less,
Ru: 0% or more and 0.15% or less,
Rh: 0% or more and 0.15% or less,
Os: 0% or more and 0.15% or less,
Ir: 0% or more and 0.15% or less,
Pt: 0% or more and 0.15% or less,
REM: 0.001% or more and 0.10% or less,
N: 0% or more and 0.03% or less,
C: 0% or more and 0.18% or less,
H: 0% or more and 0.015% or less,
O: 0% or more and 0.35% or less,
Fe: 0% or more and 0.30% or less, and the total of Pd, Ru, Rh, Os, Ir and Pt: 0.01% or more and 0.15% or less,
It is a titanium alloy with the remainder consisting of Ti and impurities.
　不純物は、添加の意図に関係なく、チタン中に存在し、得られるチタン材において本来存在する必要のない成分である。「不純物」なる用語は、チタンを工業的に製造する際に原料または製造環境等から混入する不純物を含む概念である。不純物としては、例えば、Ｃｌ、Ｎａ、Ｍｇ、Ｃａ、およびＢ、が挙げられる。不純物の各元素の含有量は、好ましくは０．１質量％以下であり、総量は、好ましくは０．４質量％以下である。 Impurities exist in titanium regardless of the intention of addition, and are components that do not originally need to be present in the resulting titanium material. The term "impurity" is a concept that includes impurities that are mixed in from raw materials or the manufacturing environment when titanium is industrially manufactured. Examples of impurities include Cl, Na, Mg, Ca, and B. The content of each impurity element is preferably 0.1% by mass or less, and the total amount is preferably 0.4% by mass or less.
　チタン基材１０は、通常、板、条、管、棒線であるか、またはこれらが適宜加工された形状をなす。チタン基材１０は、任意の形状、例えば、球状または直方体状であってもよい。 The titanium base material 10 is usually a plate, strip, tube, wire rod, or a shape obtained by appropriately processing these. The titanium base material 10 may have any shape, for example, a spherical shape or a rectangular parallelepiped shape.
（酸化皮膜２０）
　チタン基材１０の表面には酸化皮膜２０が形成されている。酸化皮膜２０の厚さは特に限定されないが、３０．０ｎｍを超えると、光の干渉作用によってチタン材１の発色に影響を及ぼす場合がある。そのため、酸化皮膜２０の厚さは、好ましくは３０．０ｎｍ以下である。酸化皮膜２０の厚さは、光の干渉作用による発色の抑制の観点からは、より好ましくは２５．０ｎｍ以下であり、更に好ましくは２０．０ｎｍ以下である。酸化皮膜２０の厚さは、０ｎｍ超であるが、例えば、１０．０ｎｍ以上であってもよい。また、チタン材の耐変色性は、酸化皮膜２０の厚さの確保によって向上する。そのため、耐変色性向上の観点からは、チタン材１の表面の酸化皮膜２０の厚さはより好ましくは１２．０ｎｍ以上である。 (Oxide film 20)
An oxide film 20 is formed on the surface of the titanium base material 10. The thickness of the oxide film 20 is not particularly limited, but if it exceeds 30.0 nm, the coloring of the titanium material 1 may be affected due to light interference. Therefore, the thickness of the oxide film 20 is preferably 30.0 nm or less. The thickness of the oxide film 20 is more preferably 25.0 nm or less, and even more preferably 20.0 nm or less, from the viewpoint of suppressing color development due to light interference. The thickness of the oxide film 20 is more than 0 nm, but may be, for example, 10.0 nm or more. Further, the color fastness of the titanium material is improved by ensuring the thickness of the oxide film 20. Therefore, from the viewpoint of improving color fastness, the thickness of the oxide film 20 on the surface of the titanium material 1 is more preferably 12.0 nm or more.
　酸化皮膜２０の厚さは、ＧＤＳによって測定される。ＧＤＳによる測定は、以下の方法で行われる。ＧＤＳによる測定は、株式会社堀場製作所製ＪＯＢＩＮ　ＹＶＯＮ　ＧＤ－Ｐｒｏｆｉｌｅｒ２を用いて、３５Ｗの定電力モードで行い、アルゴンガスの圧力を６００Ｐａ、放電範囲を直径４ｍｍとする。ＧＤＳによる測定における測定ピッチは０．５ｎｍである。ＧＤＳによる測定では、チタン材１の表面から、Ｏ（酸素）、Ｎ（窒素）、Ｃ（炭素）、Ｈ（水素）およびＴｉの分析が行われる。上記各元素の濃度（原子％）は、上記元素の合計を１００原子％として算出される。酸化皮膜２０の厚さは、ＧＤＳによって測定される酸素濃度から求められる。具体的には、表面から、酸素濃度が最大値に対して半減した位置までの厚さ方向の距離が酸化皮膜２０の厚さである。平均窒素濃度、平均炭素濃度および平均水素濃度は、各測定点の窒素濃度、炭素濃度および水素濃度の数値の算術平均値である。 The thickness of the oxide film 20 is measured by GDS. Measurement by GDS is performed in the following manner. GDS measurements are performed using JOBIN YVON GD-Profiler 2 manufactured by Horiba Ltd. in a constant power mode of 35 W, with an argon gas pressure of 600 Pa and a discharge range of 4 mm in diameter. The measurement pitch in GDS measurement is 0.5 nm. In the GDS measurement, O (oxygen), N (nitrogen), C (carbon), H (hydrogen), and Ti are analyzed from the surface of the titanium material 1. The concentration (atomic %) of each of the above elements is calculated with the total of the above elements as 100 atomic %. The thickness of the oxide film 20 is determined from the oxygen concentration measured by GDS. Specifically, the distance in the thickness direction from the surface to the position where the oxygen concentration is half of the maximum value is the thickness of the oxide film 20. The average nitrogen concentration, average carbon concentration, and average hydrogen concentration are the arithmetic average values of the nitrogen concentration, carbon concentration, and hydrogen concentration values at each measurement point.
　チタン基材１０における酸化皮膜２０との界面近傍の窒化物由来の窒素濃度は、ＸＰＳで測定した酸化皮膜２０における窒素濃度の最大値未満且つ７原子％以下であることが好ましい。後述する本実施形態に係るチタン材１の製造方法により、酸化皮膜２０に窒化物が形成されるが、当該方法によればチタン基材１０と酸化皮膜２０との界面近傍に形成される窒化物は存在しないか極少量である。チタン基材１０である母材の窒素含有量は、化学分析で得られる値では、０．０５～０．０７質量％程度であり、多くとも０．２０原子％程度と、不純物レベルである。この含有量はチタン中の窒素の固溶限以下であるため、窒化物は形成されない。したがって、チタン基材１０と酸化皮膜２０との界面近傍に窒化物が存在する場合、その窒化物は、本実施形態に係るチタン材１の製造方法の一例における焼鈍処理の際に窒素が表面から内部に拡散して形成されたものである。そのため、チタン基材１０における酸化皮膜２０との界面近傍の窒化物由来の窒素濃度は、ＸＰＳで測定した酸化皮膜２０における窒素濃度の最大値未満且つ７原子％以下であることが好ましい。チタン基材１０における酸化皮膜２０との界面近傍の窒化物由来の窒素濃度がＸＰＳで測定した酸化皮膜２０における窒素濃度の最大値未満且つ７．０原子％以下であると、チタン材１が長期に亘って酸性雨環境に曝された場合の酸化皮膜の成長が抑制され、変色が抑制される。チタン基材１０における酸化皮膜２０との界面近傍の窒化物由来の窒素濃度は、より好ましくは、酸化皮膜２０における窒素濃度の最大値未満且つ３．０原子％以下である。一方、チタン基材１０における酸化皮膜２０との界面近傍の窒化物由来の窒素濃度の下限は制限されない。そのため、本実施形態に係るチタン材１の製造方法の一例によれば、チタン基材１０における酸化皮膜２０との界面近傍の窒化物由来の窒素濃度の下限は、０原子％であるが、ＸＰＳのピーク分離に起因するもの（ゼロにはならない）も加味すると０．５原子％程度となる場合がある。 The concentration of nitrogen derived from nitride near the interface with the oxide film 20 in the titanium base material 10 is preferably less than the maximum value of the nitrogen concentration in the oxide film 20 measured by XPS and 7 atomic % or less. Nitride is formed in the oxide film 20 by the method for manufacturing the titanium material 1 according to the present embodiment, which will be described later. is non-existent or in very small amounts. The nitrogen content of the base material, which is the titanium base material 10, is about 0.05 to 0.07% by mass, and at most about 0.20 atomic%, which is at the impurity level, according to the value obtained by chemical analysis. Since this content is below the solid solubility limit of nitrogen in titanium, no nitride is formed. Therefore, when nitride exists near the interface between the titanium base material 10 and the oxide film 20, the nitride is removed from the surface by nitrogen during the annealing treatment in the example of the method for manufacturing the titanium material 1 according to the present embodiment. It is formed by diffusion inside. Therefore, the concentration of nitrogen derived from nitride near the interface with the oxide film 20 in the titanium base material 10 is preferably less than the maximum value of the nitrogen concentration in the oxide film 20 measured by XPS and 7 atomic % or less. If the nitrogen concentration derived from nitride near the interface with the oxide film 20 in the titanium base material 10 is less than the maximum value of the nitrogen concentration in the oxide film 20 measured by XPS and 7.0 atomic % or less, the titanium material 1 is The growth of an oxide film when exposed to an acid rain environment is suppressed, and discoloration is suppressed. The concentration of nitrogen derived from nitride near the interface with the oxide film 20 in the titanium base material 10 is more preferably less than the maximum value of the nitrogen concentration in the oxide film 20 and 3.0 atomic % or less. On the other hand, the lower limit of the nitrogen concentration derived from nitride near the interface with the oxide film 20 in the titanium base material 10 is not limited. Therefore, according to an example of the method for manufacturing the titanium material 1 according to the present embodiment, the lower limit of the concentration of nitrogen derived from nitrides near the interface with the oxide film 20 in the titanium base material 10 is 0 at. When taking into account what is caused by peak separation (which does not become zero), the amount may be about 0.5 at.%.
　なお、チタン基材１０における酸化皮膜２０との界面近傍とは、ＸＰＳで測定したときの当該界面からチタン基材側に２０ｎｍの範囲を言う。後述のＸＰＳで測定した図（例えば、図４）にて、ＸＰＳで測定した酸素濃度が最大値の１／２になる位置を前記の界面とする。そのため、ＸＰＳで測定した酸素濃度が最大値の１／２になる位置からチタン基材側まで２０ｎｍ範囲を、チタン基材１０における酸化皮膜２１との界面近傍とする。チタン基材１０における酸化皮膜２０との界面近傍は、表層部３０とは異なる領域である。
　酸化皮膜２０は、ＧＤＳまたはＸＰＳで同定できるが、各測定方法で得られる酸化皮膜の厚さは、測定方法が異なるため厳密に一致しない事が多い。しかしながら、各測定方法で、酸素濃度が最大値の１／２になる位置を酸化皮膜とする点で、酸化皮膜の定義は一致する。本願では、チタン基材１０における酸化皮膜２０との界面近傍の窒化物由来の窒素濃度を測定する際の酸化皮膜はＸＰＳで測定する。 Note that the vicinity of the interface between the titanium base material 10 and the oxide film 20 refers to a range of 20 nm from the interface to the titanium base material side when measured by XPS. In a diagram (for example, FIG. 4) measured by XPS, which will be described later, the position where the oxygen concentration measured by XPS is 1/2 of the maximum value is defined as the interface. Therefore, a 20 nm range from the position where the oxygen concentration measured by XPS becomes 1/2 of the maximum value to the titanium base material side is defined as the vicinity of the interface with the oxide film 21 in the titanium base material 10. The vicinity of the interface with the oxide film 20 in the titanium base material 10 is a region different from the surface layer portion 30.
The oxide film 20 can be identified by GDS or XPS, but the thickness of the oxide film obtained by each measurement method often does not exactly match because the measurement methods are different. However, in each measurement method, the definition of an oxide film is the same in that the position where the oxygen concentration is 1/2 of the maximum value is defined as an oxide film. In this application, when measuring the nitrogen concentration derived from nitride near the interface with the oxide film 20 in the titanium base material 10, the oxide film is measured by XPS.
　酸化皮膜２０は、窒化物由来の窒素を含有することが好ましい。酸化皮膜２０における窒化物由来の窒素は、Ｘ線光電子分光法（Ｘ－ｒａｙ　Ｐｈｏｔｏｅｌｅｃｔｒｏｎ　Ｓｐｅｃｔｒｏｓｃｏｐｙ；ＸＰＳ）により測定される。図２は、本実施形態に係るチタン材１のＸ線光電子分光法によるスペクトルの深さ方向の変化の一例を示す図である。図３は、一般のチタン材のＸ線光電子分光法によるスペクトルの深さ方向の変化の一例を示す図である。図２（Ａ）および図３（Ａ）は、Ｎ１ｓスペクトルの深さ方向の変化、図２（Ｂ）および図３（Ｂ）は、Ｃ１ｓスペクトルの深さ方向の変化、図２（Ｃ）および図３（Ｃ）は、Ｏ１ｓスペクトルの深さ方向の変化、図２（Ｄ）および図３（Ｄ）は、Ｔｉ２ｐスペクトルの深さ方向の変化を示している。図２（Ｃ）に示すように、本実施形態に係るチタン材１では、酸化皮膜２０に相当する深さで窒化物由来の明瞭なピークが確認されることがある。一方で、図３（Ｃ）に示すように、一般のチタン材では、窒化物由来のピークが極めて小さい。このように、本実施形態に係るチタン材１は、酸化皮膜２０に所定量の窒化物由来の窒素を含有することが好ましい。以下に、酸化皮膜２０における窒化物由来の窒素の含有量について、詳細に説明する。なお、本実施形態に係るチタン材１では、図２（Ｃ）の窒化物（Ｎｉｔｒｉｄｅ）のピーク強度が増加してくるのに伴って、図２（Ａ）のＴｉＮが関与するピークの強度も増加していることから、図２（Ｃ）の窒化物は、チタンの窒化物に由来すると考えられる。 It is preferable that the oxide film 20 contains nitrogen derived from nitride. Nitrogen derived from nitride in the oxide film 20 is measured by X-ray Photoelectron Spectroscopy (XPS). FIG. 2 is a diagram showing an example of a change in the spectrum in the depth direction by X-ray photoelectron spectroscopy of the titanium material 1 according to the present embodiment. FIG. 3 is a diagram showing an example of a change in the spectrum in the depth direction of a general titanium material by X-ray photoelectron spectroscopy. Figures 2(A) and 3(A) show changes in the N1s spectrum in the depth direction, Figures 2(B) and 3(B) show changes in the C1s spectrum in the depth direction, Figures 2(C) and FIG. 3(C) shows changes in the O1s spectrum in the depth direction, and FIGS. 2(D) and 3(D) show changes in the Ti2p spectrum in the depth direction. As shown in FIG. 2C, in the titanium material 1 according to this embodiment, a clear peak derived from nitrides may be observed at a depth corresponding to the oxide film 20. On the other hand, as shown in FIG. 3(C), in general titanium materials, the peak derived from nitrides is extremely small. As described above, it is preferable that the titanium material 1 according to the present embodiment contains a predetermined amount of nitrogen derived from nitride in the oxide film 20. Below, the content of nitrogen derived from nitride in the oxide film 20 will be explained in detail. In addition, in the titanium material 1 according to the present embodiment, as the peak intensity of nitride in FIG. 2(C) increases, the intensity of the peak related to TiN in FIG. 2(A) also increases. Since the nitride in FIG. 2(C) increases, it is considered that the nitride in FIG. 2(C) is derived from titanium nitride.
　酸化皮膜２０における窒化物由来の窒素含有量（窒素濃度の最大値）は、２．０～１０．０原子％であることが好ましい。酸化皮膜２０における窒化物由来の窒素含有量とは、ＸＰＳにより測定した酸化皮膜２０中の窒化物由来の窒素濃度の最大値をいう。未発色材にて、酸化皮膜２０が窒化物由来の窒素を２．０原子％以上含有すると、耐変色性が一層向上する。この理由は必ずしも明らかではないが、酸化皮膜２０内に窒化物が存在すると、原子配列が乱れ、酸化皮膜２０内に歪分布が変化すること、または、導電性が変化してナノメートルレベルの電位分布が変化すること等により、酸化皮膜２０におけるイオンの透過を遮蔽する機能（遮蔽機能）が変化したためであると考えられる。
　酸化皮膜２０における窒化物由来の窒素含有量が２．０原子％以上であると、より確実に遮蔽機能を向上させ、耐変色性向上の効果をより確実に得ることができる。酸化皮膜２０における窒化物由来の窒素含有量は、製造上の安定性を考慮すると、より好ましくは、４．０原子％以上である。一方、酸化皮膜２０における窒化物由来の窒素含有量が１０．０原子％超であると、遮蔽機能が低下し、耐変色性向上の効果が得られない場合があるが、酸化皮膜２０における窒化物由来の窒素含有量が１０．０原子％以下であると、遮蔽機能が維持され、より高い耐変色性向上の効果が得られる。酸化皮膜２０における窒化物由来の窒素含有量は、製造上の安定性を考慮すると、より好ましくは、８．０原子％以下である。 The nitrogen content (maximum value of nitrogen concentration) derived from nitride in the oxide film 20 is preferably 2.0 to 10.0 at.%. The nitride-derived nitrogen content in the oxide film 20 refers to the maximum concentration of nitride-derived nitrogen in the oxide film 20 measured by XPS. When the oxide film 20 contains 2.0 atomic % or more of nitrogen derived from nitride using a non-coloring material, the discoloration resistance is further improved. The reason for this is not necessarily clear, but when nitride exists in the oxide film 20, the atomic arrangement is disturbed and the strain distribution in the oxide film 20 changes, or the conductivity changes and the potential reaches a nanometer level. This is considered to be because the function of blocking ion transmission (shielding function) in the oxide film 20 has changed due to a change in distribution or the like.
When the nitrogen content derived from nitride in the oxide film 20 is 2.0 atomic % or more, the shielding function can be improved more reliably, and the effect of improving color fastness can be more reliably obtained. The nitrogen content derived from nitride in the oxide film 20 is more preferably 4.0 atomic % or more in consideration of manufacturing stability. On the other hand, if the nitrogen content derived from nitride in the oxide film 20 exceeds 10.0 atomic %, the shielding function may deteriorate and the effect of improving color fastness may not be obtained. When the nitrogen content derived from nitrogen is 10.0 at % or less, the shielding function is maintained and a higher effect of improving color fastness can be obtained. The nitrogen content derived from nitride in the oxide film 20 is more preferably 8.0 atomic % or less in consideration of manufacturing stability.
　さらに、本発明者らは、酸化皮膜２０における窒化物由来の窒素の分布を制御することで耐変色性を向上させることに想到した。図４は、本実施形態に係るチタン材１（本発明例）および一般のチタン材（従来例）のＸ線光電子分光法による深さ方向の元素濃度分布の一例を示す図である。図４における横軸のスパッタ深さは、ＳｉＯ２のスパッタリング速度で換算した深さである。図４の本発明例は、図２に示した本実施形態に係るチタン材についての元素濃度分布である。図４の従来例は、図３に示した一般のチタン材（工業用純チタン１種）についての元素濃度分布である。 Furthermore, the present inventors came up with the idea of improving discoloration resistance by controlling the distribution of nitrogen derived from nitrides in the oxide film 20. FIG. 4 is a diagram showing an example of the element concentration distribution in the depth direction of the titanium material 1 according to the present embodiment (example of the present invention) and a general titanium material (example of the prior art) measured by X-ray photoelectron spectroscopy. The sputtering depth on the horizontal axis in FIG. 4 is the depth converted by the SiO 2 sputtering rate. The example of the present invention shown in FIG. 4 is an element concentration distribution for the titanium material according to the present embodiment shown in FIG. The conventional example shown in FIG. 4 is an element concentration distribution for the general titanium material (industrial pure titanium type 1) shown in FIG.
　図４に示すように、本実施形態に係るチタン材１は、ＳｉＯ２のスパッタリング速度で換算したときのスパッタ深さが２～１０ｎｍの位置に、窒化物由来の窒素濃度が最大となっている。一方で、一般のチタン材では、窒素濃度は極めて小さい。したがって、酸化皮膜２０における窒化物由来の窒素濃度が最大となる深さは、ＳｉＯ２のスパッタリング速度で換算したときに２～１０ｎｍであることが好ましい。なお、当該スパッタ深さの上限は、上述した酸化皮膜２０との界面近傍の範囲を含む３０ｎｍ以上とすることが好ましい。また、酸化皮膜２０の厚さに応じて変更されてもよく、酸化皮膜２０の厚さの３倍程度以上にするのが好ましい。 As shown in FIG. 4, in the titanium material 1 according to the present embodiment, the nitrogen concentration derived from nitrides is maximum at a position where the sputtering depth is 2 to 10 nm when converted to the SiO 2 sputtering rate. . On the other hand, in general titanium materials, the nitrogen concentration is extremely low. Therefore, the depth at which the concentration of nitrogen derived from nitride in the oxide film 20 is maximum is preferably 2 to 10 nm when converted to the sputtering rate of SiO 2 . Note that the upper limit of the sputtering depth is preferably 30 nm or more, including the area near the interface with the oxide film 20 described above. Further, it may be changed depending on the thickness of the oxide film 20, and is preferably about three times or more the thickness of the oxide film 20.
　さらに、本発明者らは、上記の酸化皮膜２０における窒化物由来の窒素濃度が最大となる深さでの窒素濃度が耐変色性に及ぼす影響を調査した。図５は、酸化皮膜２０内の窒化物由来の窒素の濃度の最大値と変色試験前後の色差ΔＥ＊ａｂとの関係を示す図である。 Furthermore, the present inventors investigated the influence of the nitrogen concentration at the depth where the nitrogen concentration derived from nitride in the oxide film 20 becomes maximum on the discoloration resistance. FIG. 5 is a diagram showing the relationship between the maximum concentration of nitrogen derived from nitride in the oxide film 20 and the color difference ΔE * ab before and after the discoloration test.
　色差ΔＥ＊ａｂは、以下の方法で求めた。ｐＨ３硫酸水溶液に６０℃で４週間浸漬し、浸漬前後のチタン材表面のＬ＊ａ＊ｂ＊を測定し、ＪＩＳ　Ｚ　８７３０：２００９に準拠して求められる明度Ｌ＊および色度ａ＊、ｂ＊それぞれの浸漬前後の差ΔＬ＊、Δａ＊、Δｂ＊から、
　ΔＥ＊ａｂ＝［（ΔＬ＊）２＋（Δａ＊）２＋（Δｂ＊）２］１／２
に従って算出した。色差ΔＥ＊ａｂが小さいほど試験前後での変色の程度が小さく、耐変色性に優れること意味する。 The color difference ΔE * ab was determined by the following method. It was immersed in a pH 3 sulfuric acid aqueous solution at 60°C for 4 weeks, and the L * a * b * of the titanium material surface was measured before and after immersion, and the lightness L * and chromaticity a * , b determined in accordance with JIS Z 8730:2009. * From the differences ΔL * , Δa * , Δb * before and after immersion,
ΔE * ab = [(ΔL * ) 2 + (Δa * ) 2 + (Δb * ) 2 ] 1/2
Calculated according to The smaller the color difference ΔE * ab, the smaller the degree of discoloration before and after the test, which means that the discoloration resistance is excellent.
　図５に示すように、酸化皮膜２０における窒化物由来の窒素濃度が最大となる深さでの窒素濃度が２．０原子％未満の場合、遮蔽性が十分に高まらず、色差が８を超える場合があった。一方、窒化物由来の窒素濃度が１０．０原子％を超えると遮蔽性が低下し、色差が８を超える場合があった。また、酸化皮膜２０における窒化物由来の窒素濃度が最大となる深さでの窒素濃度が１０．０原子％を超える場合、金色や黄色味かかった色調になることがあった。金色や黄色味かかった色調になる場合、色調が変化するため、チタンそのものの銀色が求められるような用途には適さないことがある。この色味の変化は、チタンの窒化物の物質色が顕在化したためと推測される。よって、酸化皮膜２０における窒化物由来の窒素濃度が最大となる深さでの窒素濃度は、２．０～１０．０原子％である。 As shown in FIG. 5, when the nitrogen concentration at the depth where the nitrogen concentration derived from nitride in the oxide film 20 is maximum is less than 2.0 at%, the shielding property is not sufficiently increased and the color difference exceeds 8. There was a case. On the other hand, when the concentration of nitrogen derived from nitride exceeds 10.0 atomic %, the shielding performance decreases, and the color difference may exceed 8. Further, when the nitrogen concentration at the depth where the nitrogen concentration derived from nitride in the oxide film 20 is maximum exceeds 10.0 at.%, the color tone may be golden or yellowish. When the color tone becomes golden or yellowish, the color tone changes, so it may not be suitable for applications where the silver color of titanium itself is required. This change in color is presumed to be due to the material color of titanium nitride becoming apparent. Therefore, the nitrogen concentration at the depth where the nitride-derived nitrogen concentration in the oxide film 20 is maximum is 2.0 to 10.0 at.%.
　さらに、図５に示すように、酸化皮膜２０における窒化物由来の窒素濃度が最大となる深さでの窒素濃度が、同じ深さにおける炭化物由来の炭素濃度未満になると色差が８を超える場合があった。これも前述したように、酸化皮膜２０内の歪分布に影響すること、導電性が変化してナノメートルレベルの電位分布に影響すること等に起因すると考えられる。よって、酸化皮膜２０における窒化物由来の窒素濃度が最大となる深さでの窒素濃度が、酸化皮膜２０における窒化物由来の窒素濃度が最大となる位置の炭化物由来の炭素濃度以上であることが好ましい。 Furthermore, as shown in FIG. 5, if the nitrogen concentration at the depth where the nitride-derived nitrogen concentration in the oxide film 20 is maximum is less than the carbide-derived carbon concentration at the same depth, the color difference may exceed 8. there were. As described above, this is also considered to be due to the fact that the strain distribution within the oxide film 20 is affected, the conductivity changes, and the potential distribution at the nanometer level is affected. Therefore, the nitrogen concentration at the depth where the nitride-derived nitrogen concentration in the oxide film 20 is maximum is equal to or higher than the carbide-derived carbon concentration at the position where the nitride-derived nitrogen concentration in the oxide film 20 is maximum. preferable.
　チタン基材１０および酸化皮膜２０における、窒化物、炭化物、酸化物に由来するＮ、Ｃ、ＯおよびＴｉの濃度を算出は、Ｘ線光電子分光分析法を用い、チタン材の表面をＡｒイオンスパッタリングしで行うことができる。詳細には、分析条件を、Ｘ線源：ｍｏｎｏ－ＡｌＫα（ｈν:１４８６．６ｅＶ）、ビーム径：２００μｍΦ（≒分析領域）、検出深さ：数ｎｍ、取込角度：４５°、スパッタ条件：Ａｒ＋、スパッタレート４．３ｎｍ/ｍｉｎ.（ＳｉＯ２換算値）とする。ＳｉＯ２換算値とは、あらかじめエリプソメーターを用いて厚さを測定したＳｉＯ２膜を用いて、同一測定条件で求めたときのスパッタリング速度である。
　結合エネルギーが約３９３～４０８ｅＶの位置に表れるピークをＮ１ｓのピークとして測定し、有機物由来のＮを約３９９～４０１ｅＶ、窒化物由来のＮを約３９７±１ｅＶとして分離する。結合エネルギーが約２８０～３９５ｅＶの位置に表れるピークをＣ１ｓのピークとし測定し、有機物由来のＣを約２８４～２８９ｅＶ、炭化物由来のＣを約２８１．５±１ｅＶとして分離する。結合エネルギーが約５２５～５４０ｅＶの位置に表れるピークをＯ１ｓのピークとして測定し、有機物由来のＯを約３９９～４０１ｅＶ、金属酸化物由来のＯを約５２９．５～５３０．５ｅＶとする。結合エネルギーが４５０～４７０ｅＶの位置に表れるピークをＴｉ２ｐのピークとして測定する。上記の物質の結合エネルギーは一般的な値であり、測定試料の帯電等によって変化し得る。その帯電補正法の一つとして、有機物由来のＣにおけるＣ-Ｃ結合のピーク位置をもとに補正する方法が適用できる。
　これらのピークを用いた一般的な解析手法として、解析ソフトウェアであるＭｕｌｔｉＰａｋを使用しての、元素濃度、化学状態別の濃度を解析することができる。一般的な手順を以下に記す。Ｓｈｉｒｌｅｙ法に基づいてバックグラウンドを補正する。次いで、化合物に関してはＧａｕｓｓ－Ｌｏｒｅｎｔｓ関数を用いて、金属の場合はＡｓｙｍｍｅｔｒｉｃ関数を用いて各元素で化学状態別にピークをフィッティングする。そして、各化学状態由来のピークの面積比率を元素の濃度(原子％)に乗じて、化学状態別の濃度（原子％）を算出する。このような手順で窒化物由来の窒素の含有量、炭化物由来の炭素の含有量を求める。なお、前記の元素の濃度は、ＸＰＳで検出された各元素にて、その元素に係るすべてのピークを含めての（分離せずに）ピーク面積を算出し、これに元素毎の感度係数で除して、百分率としたものである。
　ここまで、酸化皮膜２０における窒化物由来の窒素の含有量について、詳細に説明した。 The concentrations of N, C, O, and Ti derived from nitrides, carbides, and oxides in the titanium base material 10 and the oxide film 20 are calculated by using X-ray photoelectron spectroscopy and Ar ion sputtering on the surface of the titanium material. This can be done with In detail, the analysis conditions are: Ar + and a sputtering rate of 4.3 nm/min. (SiO 2 equivalent value). The SiO 2 equivalent value is a sputtering rate determined under the same measurement conditions using an SiO 2 film whose thickness was measured in advance using an ellipsometer.
A peak appearing at a position where the binding energy is approximately 393 to 408 eV is measured as the N1s peak, and N derived from organic matter is separated as approximately 399 to 401 eV, and N derived from nitride is determined to be approximately 397±1 eV. A peak appearing at a position where the binding energy is approximately 280 to 395 eV is measured as a C1s peak, and organic matter-derived C is determined to be approximately 284 to 289 eV, and carbide-derived C is determined to be approximately 281.5±1 eV. A peak appearing at a position where the binding energy is approximately 525 to 540 eV is measured as the O1s peak, and O derived from organic matter is approximately 399 to 401 eV, and O derived from metal oxide is approximately 529.5 to 530.5 eV. A peak appearing at a position with binding energy of 450 to 470 eV is measured as a Ti2p peak. The binding energy of the above-mentioned substances is a general value, and may change depending on the charging of the measurement sample, etc. As one of the charge correction methods, a method of correction based on the peak position of the C--C bond in C derived from an organic substance can be applied.
As a general analysis method using these peaks, it is possible to analyze element concentrations and concentrations by chemical state using MultiPak, which is analysis software. The general procedure is described below. Background is corrected based on the Shirley method. Next, peaks are fitted for each chemical state of each element using the Gauss-Lorents function for compounds and the Asymmetric function for metals. Then, the concentration (atomic %) of each chemical state is calculated by multiplying the concentration (atomic %) of the element by the area ratio of the peak derived from each chemical state. Through such a procedure, the content of nitrogen derived from nitrides and the content of carbon derived from carbides are determined. The concentration of the above elements can be determined by calculating the peak area of each element detected by XPS, including all peaks related to that element (without separating them), and then adding the sensitivity coefficient for each element to this peak area. It is calculated as a percentage.
Up to this point, the content of nitrogen derived from nitrides in the oxide film 20 has been described in detail.
（表層部３０）
　チタン材１の耐変色性は、表層部３０の平均窒素濃度および平均炭素濃度の減少によって向上する。チタン材１の表面から上記方法のＧＤＳによって厚さ方向に測定された、表層部３０の平均窒素濃度および平均炭素濃度は、耐変色性の観点から、それぞれ、１４．０原子％以下である。チタン材１の表層部３０の平均窒素濃度は、好ましくは１２．０原子％以下であり、より好ましくは１０．０原子％以下である。チタン材１の表層部３０の平均炭素濃度は、好ましくは１３．０原子％以下であり、より好ましくは１２．０原子％以下、更に好ましくは１０．０原子％以下である。チタン材１の表層部３０の平均窒素濃度は、０原子％であってもよく、１．０原子％以上であってもよい。チタン材１の表層部３０の平均炭素濃度は、０原子％であってもよく、１．０原子％以上であってもよい。 (Surface layer part 30)
The color fastness of the titanium material 1 is improved by decreasing the average nitrogen concentration and average carbon concentration of the surface layer portion 30. The average nitrogen concentration and average carbon concentration of the surface layer portion 30 measured from the surface of the titanium material 1 in the thickness direction by GDS using the above method are each 14.0 atomic % or less from the viewpoint of discoloration resistance. The average nitrogen concentration in the surface layer portion 30 of the titanium material 1 is preferably 12.0 atom % or less, more preferably 10.0 atom % or less. The average carbon concentration of the surface layer portion 30 of the titanium material 1 is preferably 13.0 atom % or less, more preferably 12.0 atom % or less, still more preferably 10.0 atom % or less. The average nitrogen concentration in the surface layer portion 30 of the titanium material 1 may be 0 atomic % or more than 1.0 atomic %. The average carbon concentration of the surface layer portion 30 of the titanium material 1 may be 0 atomic % or more than 1.0 atomic %.
　チタン材１の耐変色性は、表層部３０の平均水素濃度の減少によって更に向上する。チタン材１の表層部３０の水素濃度は、３０．０原子％以下であり、好ましくは２５．０原子％以下、より好ましくは２０．０原子％以下である。チタンは、水素と親和性の高い金属であり、表層部３０の水素濃度は１０．０原子％以上であってもよい。 The color fastness of the titanium material 1 is further improved by reducing the average hydrogen concentration in the surface layer 30. The hydrogen concentration in the surface layer portion 30 of the titanium material 1 is 30.0 atom % or less, preferably 25.0 atom % or less, more preferably 20.0 atom % or less. Titanium is a metal that has a high affinity for hydrogen, and the hydrogen concentration in the surface layer portion 30 may be 10.0 atomic % or more.
（表層部３０におけるα相のＴｉのｃ軸の格子定数の差）
　チタン材１の表層部３０におけるα相のＴｉの結晶構造は、耐変色性に影響を及ぼす。具体的には、チタン材１の表層部３０におけるα相のＴｉのｃ軸の格子定数が増加すると、耐変色性が劣化する。チタン材１の表層部３０におけるα相のＴｉのｃ軸の格子定数の増加分は、チタン材１の表面において入射角が０．３度である平行ビーム法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数と、板厚中央において集中法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数との差で評価される。チタン材１の表層部３０におけるα相のＴｉのｃ軸の格子定数の増加分は、耐変色性の観点から、０．０１５Å以下であり、好ましくは０．０１０Å以下である。チタン材１の表面のα相のＴｉのｃ軸の格子定数の増加分は、小さいほど好ましく、０Åであってもよい。この増加分が負の値になった場合、原因は測定誤差であり、増加分は０Åと見做される。 (Difference in c-axis lattice constant of α-phase Ti in surface layer 30)
The crystal structure of α-phase Ti in the surface layer 30 of the titanium material 1 affects the color fastness. Specifically, when the c-axis lattice constant of α-phase Ti in the surface layer 30 of the titanium material 1 increases, the color fastness deteriorates. The increase in the c-axis lattice constant of α-phase Ti in the surface layer 30 of the titanium material 1 is α determined by X-ray diffraction measurement using the parallel beam method at an incident angle of 0.3 degrees on the surface of the titanium material 1. It is evaluated by the difference between the c-axis lattice constant of the Ti phase and the c-axis lattice constant of the α phase Ti, which is determined by X-ray diffraction measurement using the concentration method at the center of the plate thickness. The increase in the c-axis lattice constant of α-phase Ti in the surface layer 30 of the titanium material 1 is 0.015 Å or less, preferably 0.010 Å or less, from the viewpoint of discoloration resistance. The increase in the c-axis lattice constant of α-phase Ti on the surface of the titanium material 1 is preferably as small as possible, and may be 0 Å. If this increment becomes a negative value, the cause is a measurement error, and the increment is considered to be 0 Å.
　チタン材１の表層部３０におけるα相のＴｉのｃ軸の格子定数は、チタン材表面における平行ビーム法を用いたＸ線回折測定によって求められる。平行ビーム法を用いたＸ線回折測定には、株式会社リガク製Ｘ線回折装置　ＳｍａｒｔＬａｂが使用され、Ｘ線源はＣｏ－Ｋα（波長　λ＝１．７９０２Å）である。Ｋβ線の除去にはＸ線の入射側にＷ／Ｓｉ多層膜ミラーを使用した。Ｘ線源負荷電力（管電圧／管電流）は、それぞれ、５．４ｋＷ（４０ｋＶ／１３５ｍＡ）である。Ｘ線の試料への入射角は０．３度であり、回折角２θが走査される。測定には、機械加工によって、チタン材から２５ｍｍ（縦）×５０ｍｍ（横）の寸法に切り出された試料を使用する。試料の１２．５ｍｍ（縦）×２５ｍｍ（横）を中心としてビームを照射し、試料の表面で測定を実施する。なお、切り出された試料は、測定する表面に汚れが付着している可能性があるため、アセトンやエタノールで洗浄する。 The c-axis lattice constant of α-phase Ti in the surface layer 30 of the titanium material 1 is determined by X-ray diffraction measurement using the parallel beam method on the surface of the titanium material. For the X-ray diffraction measurement using the parallel beam method, an X-ray diffraction device SmartLab manufactured by Rigaku Co., Ltd. is used, and the X-ray source is Co-Kα (wavelength λ = 1.7902 Å). To remove Kβ rays, a W/Si multilayer mirror was used on the X-ray incident side. The X-ray source load power (tube voltage/tube current) is 5.4 kW (40 kV/135 mA), respectively. The angle of incidence of the X-rays on the sample is 0.3 degrees, and the diffraction angle 2θ is scanned. For the measurement, a sample cut out from a titanium material into a size of 25 mm (vertical) x 50 mm (horizontal) by machining is used. A beam is irradiated centering on a 12.5 mm (vertical) x 25 mm (horizontal) area of the sample, and measurement is performed on the surface of the sample. Note that the cut sample may have dirt attached to the surface to be measured, so clean it with acetone or ethanol.
　チタン材の板厚中央におけるα相のＴｉの結晶構造は、集中法を用いたＸ線回折によって測定される。チタン材の板厚中央におけるα相のＴｉの結晶構造の解析に使用される試料は、チタン材の板厚中央がＸ線回折測定を行う測定面となるように、機械研磨および電解研磨によって仕上げる。集中法を用いたＸ線回折測定には、平行ビーム法を用いたＸ線回折測定に使用されるＸ線回折装置を使用すればよく、Ｘ線源、Ｋβ線の除去フィルタ、およびＸ線源負荷電力も上記平行ビーム法の条件と同一であればよい。Ｔｉの結晶構造は板厚中央であれば一様であるため、板幅、圧延方向どの箇所から試料を作製してもよい。ここでは、板幅の凡そ四分の一から中央部より試料を作製し、試験を実施した。 The crystal structure of α-phase Ti at the center of the thickness of the titanium material is measured by X-ray diffraction using the concentration method. The sample used to analyze the crystal structure of α-phase Ti at the center of the thickness of the titanium material is finished by mechanical polishing and electrolytic polishing so that the center of the thickness of the titanium material becomes the measurement surface for X-ray diffraction measurements. . For X-ray diffraction measurements using the focused method, it is sufficient to use an X-ray diffraction apparatus used for X-ray diffraction measurements using the parallel beam method, which includes an X-ray source, a Kβ ray removal filter, and an X-ray source. The load power may also be the same as the conditions for the parallel beam method. Since the crystal structure of Ti is uniform at the center of the plate thickness, samples may be prepared from any point in the width of the plate or in the rolling direction. Here, a sample was prepared from the center of the board from about a quarter of the width, and the test was conducted.
　チタン材の表面および板厚中央におけるα相のＴｉのｃ軸の格子定数は、（０００２）面の回折ピークから、スペクトリス株式会社製のソフトウェア（エキスパート・ハイスコア・プラス）を用いて算出される。チタン基材がα＋β型である場合も、α相のＴｉの回折ピークからα相のＴｉのｃ軸の格子定数が算出される。 The c-axis lattice constant of α-phase Ti on the surface of the titanium material and at the center of the plate thickness is calculated from the diffraction peak of the (0002) plane using software (Expert High Score Plus) manufactured by Spectris Co., Ltd. . Even when the titanium base material is an α+β type, the c-axis lattice constant of α-phase Ti is calculated from the diffraction peak of α-phase Ti.
（Ｒａ／ＲＳｍ：０．００６～０．０１５）
（ＲΔｑ：０．１５０～０．２８０）
　さらに、本発明者らは、チタン材の表面性状と、耐変色性との関係を詳細に検討し、チタン材の耐変色性は、チタン基材の表面の算術平均粗さＲａと輪郭曲線要素の平均長さＲＳｍの比であるＲａ／ＲＳｍ、および粗さ曲線要素の二乗平均平方根傾斜ＲΔｑが耐変色性に影響することを知見した。 (Ra/RSm: 0.006-0.015)
(RΔq: 0.150 to 0.280)
Furthermore, the present inventors investigated in detail the relationship between the surface properties of the titanium material and the color fastness, and found that the color fastness of the titanium material is determined by the arithmetic mean roughness Ra of the surface of the titanium base material and the contour curve element. It was found that Ra/RSm, which is the ratio of the average length RSm, and the root mean square slope RΔq of the roughness curve element influence the color fastness.
　算術平均粗さＲａ、輪郭曲線要素の平均長さＲＳｍ、および粗さ曲線要素の二乗平均平方根傾斜ＲΔｑは、ＪＩＳ　Ｂ　０６０１：２０１３に準拠した方法で測定することができる。なお、後述するクルトシスＲｋｕおよびスキューネスＲｓｋも、ＪＩＳ　Ｂ　０６０１：２０１３に準拠した方法で測定することができる。 The arithmetic mean roughness Ra, the average length RSm of the contour curve element, and the root mean square slope RΔq of the roughness curve element can be measured by a method compliant with JIS B 0601:2013. Note that kurtosis Rku and skewness Rsk, which will be described later, can also be measured by a method based on JIS B 0601:2013.
　本実施形態の算術平均粗さＲａは、ＪＩＳ　Ｂ　０６０１：２０１３に規定される算術平均粗さＲａであって、基準長さにおける総座標値Ｚｊの絶対値の平均である。算術平均粗さＲａは、下記式（１）より算出される。
　なお、算術平均粗さＲａの算出の基礎となる粗さ曲線は、酸化皮膜の測定断面曲線にカットオフ波長λｃ＝０．８ｍｍの低域フィルタを適用して断面曲線を取得し、更にこの段面曲線に、カットオフ波長λｓ＝２．６６７μｍの高域フィルタを適用することによって得られた粗さ曲線とする。また、粗さ曲線の基準長さは、カットオフ波長λｃと等しい長さ、すなわち、０．８ｍｍとする。λｃは、粗さ成分とうねり成分との境界を定義するフィルタである。λｓは、粗さ成分とそれより短い波長成分との境界を定義するフィルタである。 The arithmetic mean roughness Ra of this embodiment is the arithmetic mean roughness Ra defined in JIS B 0601:2013, and is the average of the absolute values of the total coordinate values Zj in the reference length. The arithmetic mean roughness Ra is calculated from the following formula (1).
Note that the roughness curve, which is the basis for calculating the arithmetic mean roughness Ra, is obtained by applying a low-pass filter with a cutoff wavelength λc = 0.8 mm to the measured cross-sectional curve of the oxide film, and then obtaining the cross-sectional curve at this stage. The roughness curve is obtained by applying a high-pass filter with a cutoff wavelength λs=2.667 μm to the surface curve. Further, the reference length of the roughness curve is set to be equal to the cutoff wavelength λc, that is, 0.8 mm. λc is a filter that defines the boundary between the roughness component and the waviness component. λs is a filter that defines the boundary between the roughness component and the shorter wavelength component.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　上記式（１）中、ｎは、測定点数であり、Ｚｊは粗さ曲線においてｊ番目測定点の高さである。 In the above formula (1), n is the number of measurement points, and Zj is the height of the jth measurement point on the roughness curve.
　輪郭曲線要素の平均長さＲＳｍは、下記式（２）より算出される。 The average length RSm of the contour curve element is calculated from the following formula (2).
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　上記式（２）中、ｍは、測定点数であり、Ｘｓｉは、基準長さにおける輪郭曲線要素の長さである。 In the above formula (2), m is the number of measurement points, and Xsi is the length of the contour curve element at the reference length.
　粗さ曲線要素の二乗平均平方根傾斜ＲΔｑは、下記式（３）より算出される。 The root mean square slope RΔq of the roughness curve element is calculated from the following formula (3).
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-M000003
　上記式（３）中、Ｎは測定点数である。（ｄＺｊ／ｄＸｊ）は、粗さ曲線においてｊ番目の測定点における局部傾斜であり、下記式（４）によって定義されている。 In the above formula (3), N is the number of measurement points. (dZj/dXj) is the local slope at the j-th measurement point in the roughness curve, and is defined by the following equation (4).
Figure JPOXMLDOC01-appb-M000004
Figure JPOXMLDOC01-appb-M000004
　上記式（４）中、ΔＸは測定間隔である。本実施形態において、測定間隔ΔＸは、以下のようにして定めればよい。すなわち、測定間隔ΔＸは、表面粗さ形状測定機によって設定される値であり、その測定長さＬを測定したとき数値データがＮ点取得された場合、測定間隔でΔＸは平均でＬ／（Ｎ－１）となる。例えば、東京精密製　ＳＵＲＦＣＯＭ　１９００ＤＸ、ソフト ＴＩＭＳ Ｖｅｒ．９．０．３を用いて、測定長さ５ｍｍを測定したとき、デジタル数字データが２５６０１点取得された場合、ΔＸは５ｍｍ／２５６００点となり平均で約０．１９５μｍとなる。 In the above formula (4), ΔX is the measurement interval. In this embodiment, the measurement interval ΔX may be determined as follows. In other words, the measurement interval ΔX is a value set by the surface roughness profile measuring machine, and if numerical data is obtained at N points when measuring the measurement length L, the measurement interval ΔX is on average L/( N-1). For example, SURFCOM 1900DX manufactured by Tokyo Seimitsu, software TIMS Ver. When measuring a measurement length of 5 mm using 9.0.3, if 25,601 points of digital numerical data are acquired, ΔX becomes 5 mm/25,600 points, which is about 0.195 μm on average.
　粗さ曲線要素の二乗平均平方根傾斜ＲΔｑは、粗さ曲線の基準長さＸに対して表面凹凸が形成する微小範囲の傾斜角（局部傾斜ｄＺ／ｄＸ）を規定したパラメータである。 The root mean square slope RΔq of the roughness curve element is a parameter that defines the slope angle (local slope dZ/dX) of the minute range formed by the surface unevenness with respect to the reference length X of the roughness curve.
　本発明者らは、Ｒａ／ＲＳｍおよびＲΔｑを変更したチタン材を作製し、チタン基材のＲａ／ＲＳｍおよびＲΔｑが耐変色性に及ぼす影響を検討した。図６は、チタン基材の算術平均粗さＲａと輪郭曲線要素の平均長さＲＳｍの比であるＲａ／ＲＳｍおよび粗さ曲線要素の二乗平均平方根傾斜ＲΔｑと耐変色性との関係を示す図である。 The present inventors produced titanium materials with different Ra/RSm and RΔq, and investigated the effects of Ra/RSm and RΔq of the titanium base material on discoloration resistance. FIG. 6 is a diagram showing the relationship between Ra/RSm, which is the ratio of the arithmetic mean roughness Ra of the titanium base material to the average length RSm of the contour curve element, the root mean square slope RΔq of the roughness curve element, and color fastness. It is.
　耐変色性は、上述したとおり、色差ΔＥ＊ａｂおよび外観観察によって評価することができる。ただし、色差ΔＥ＊ａｂを評価するための色調Ｌ＊ａ＊ｂ＊の測定では、チタン板の真上に設けられた昼光光源から光を照射する。そのため、実際の見た目とは異なる場合がある。特に、ＲΔｑが大きいチタン板では、色差ΔＥ＊ａｂが小さくても太陽光下での目視観察では変色して見える場合がある。よって、耐変色性の評価には、太陽光下での目視観察も重要である。 As described above, color fastness can be evaluated by color difference ΔE * ab and appearance observation. However, in measuring the color tone L * a * b * for evaluating the color difference ΔE * ab, light is irradiated from a daylight light source provided directly above the titanium plate. Therefore, the actual appearance may differ. In particular, a titanium plate with a large RΔq may appear discolored when visually observed under sunlight even if the color difference ΔE * ab is small. Therefore, visual observation under sunlight is also important for evaluating color fastness.
　図６における「〇」は、色差ΔＥ＊ａｂが５以下であり且つ目視による官能評価にて変色が目立たないとした人の比率が８０％以上であった条件を、「×」は色差ΔＥ＊ａｂが５以下であるが目視による官能評価にて変色が目立たないとした人の比率が８０％未満であった条件を示している。ここで、この目視観察による官能評価は、先の本変色促進試験に供していないチタン材と本変色促進試験後のチタン材を平板上に並べておき、１０名の評価人が太陽光下で様々な角度から見比べて、変色が目立って視認される角度があったか否かを判断した。変色が目立たないとした人の比率を比較した。なお、この目視観察は、実際の建築物の屋根や壁を想定した条件であり、見る角度によって色調が変わることも想定しての評価である。 In FIG. 6, "○" indicates a condition in which the color difference ΔE * ab was 5 or less and the proportion of people who said that the discoloration was not noticeable in visual sensory evaluation was 80% or more, and "x" indicates the color difference ΔE * Conditions are shown in which, although the ab is 5 or less, the proportion of people who said that the discoloration was not noticeable in visual sensory evaluation was less than 80%. Here, this sensory evaluation by visual observation was carried out by arranging the titanium material that had not been subjected to the previous main discoloration acceleration test and the titanium material after the main discoloration acceleration test on a flat plate, and having 10 evaluators examine the titanium material under sunlight under various conditions. We compared the results from different angles to determine whether there were any angles where the discoloration was noticeable. We compared the proportion of people who said their discoloration was not noticeable. Note that this visual observation is performed under conditions that assume the roof and walls of an actual building, and the evaluation assumes that the color tone changes depending on the viewing angle.
　図６に示すように、本実施形態に係るチタン材は、その表面について、算術平均粗さＲａと輪郭曲線要素の平均長さＲＳｍの比であるＲａ／ＲＳｍが０．００６～０．０１５であり、かつ、粗さ曲線要素の二乗平均平方根傾斜ＲΔｑが０．１５０～０．２８０である場合に、より高温かつ酸性環境下においても耐変色性に優れることが判明した。このようなチタン材は、高温かつ酸性環境下においても耐変色性を優れるチタン材は、長期に亘る変色をより一層抑制することが可能である。 As shown in FIG. 6, the titanium material according to the present embodiment has a surface with Ra/RSm, which is the ratio of the arithmetic mean roughness Ra to the average length RSm of the contour curve elements, of 0.006 to 0.015. It has been found that when the roughness curve element has a root mean square slope RΔq of 0.150 to 0.280, the color fastness is excellent even at higher temperatures and in an acidic environment. Such titanium materials have excellent discoloration resistance even under high temperature and acidic environments, and can further suppress discoloration over a long period of time.
　Ｒａ／ＲＳｍが０．００６未満であると、チタン基材表面の凹凸が小さく、その凹凸の間隔が広い。Ｒａ／ＲＳｍが０．００６未満であると、チタン材の表面が比較的平滑であり、酸化皮膜の表面で反射した光とチタン基材表面で反射した光の光路差により、その光路差に応じて強められた光の色が認識される場合がある。すなわち、チタン材が変色する場合がある。Ｒａ／ＲＳｍが０．００６～０．０１５であれば、チタン材表面の比較的大きな傾斜によって、酸化皮膜の表面で反射した光とチタン基材表面で反射した光の光路差が小さくなり、可視光の範囲で強められる光がないため、変色が抑制されると考えられる。この変色が抑制される機構から考えると、Ｒａ／ＲＳｍの上限を０．０１５に限定する理由はないものの、０．０１５超のような深く狭い谷状の凹凸を工業的に作製することが困難である。そのため、Ｒａ／ＲＳｍの上限は、本発明の効果が明確に得られる０．０１５であることが好ましい。 When Ra/RSm is less than 0.006, the irregularities on the surface of the titanium base material are small and the intervals between the irregularities are wide. When Ra/RSm is less than 0.006, the surface of the titanium material is relatively smooth, and due to the optical path difference between the light reflected on the surface of the oxide film and the light reflected on the titanium base material surface, In some cases, the color of the light that is enhanced by the light may be recognized. That is, the titanium material may change color. If Ra/RSm is 0.006 to 0.015, the optical path difference between the light reflected on the surface of the oxide film and the light reflected on the surface of the titanium base material becomes small due to the relatively large slope of the titanium material surface. It is thought that discoloration is suppressed because there is no light that is intensified in the light range. Considering the mechanism by which this discoloration is suppressed, there is no reason to limit the upper limit of Ra/RSm to 0.015, but it is difficult to industrially produce deep and narrow valley-like irregularities with a value exceeding 0.015. It is. Therefore, the upper limit of Ra/RSm is preferably 0.015 so that the effects of the present invention can be clearly obtained.
　ＲΔｑが０．１５０以上であると、酸化皮膜におけるより微細な凹凸の傾斜が大きく、この局部的な傾斜によってチタン基材表面に照射する光の正反射が抑制され、拡散反射される。そのため、酸化皮膜の表面で反射する光の方向に反射するチタン基材表面での反射光の強度が小さくなる。その結果、強められた光の色は認識されにくい。ＲΔｑが０．１５０未満であると、上記作用が生じないため、チタン材が変色して見える場合がある。一方、ＲΔｑが０．２８０超であると、色差は５以下と小さいものの太陽光下では変色が目立って見える角度がある場合がある。これは、ＲΔｑが０．２８０超であると、斜めからチタン材を見た場合、正反射方向となってしまう傾斜が存在してしまい、酸化皮膜の厚さが増加したことによる干渉色が強められて、目視で認識されるようになるためと考えられる。 When RΔq is 0.150 or more, the inclination of the finer unevenness in the oxide film is large, and this local inclination suppresses regular reflection of light irradiated onto the titanium base material surface and causes it to be diffusely reflected. Therefore, the intensity of the light reflected on the surface of the titanium base material that is reflected in the direction of the light reflected on the surface of the oxide film becomes small. As a result, the color of the enhanced light is difficult to perceive. When RΔq is less than 0.150, the above effect does not occur, and the titanium material may appear discolored. On the other hand, when RΔq is more than 0.280, although the color difference is as small as 5 or less, there may be angles where discoloration is noticeable under sunlight. This is because when RΔq exceeds 0.280, when the titanium material is viewed from an angle, there is an inclination that becomes a specular reflection direction, and the interference color due to the increased thickness of the oxide film becomes stronger. This is thought to be due to the fact that the image can be recognized visually.
　Ｒａ／ＲＳｍが０．００６～０．０１５であり、かつ、粗さ曲線要素の二乗平均平方根傾斜ＲΔｑが０．１５０～０．２８０であれば、上記作用が重畳して得られるため、チタン材の変色がより一層抑制される。さらに、上記の表面状態を有するチタン材は、その表面に酸化皮膜が数十ｎｍ程度に成長したとしても、色調の変化つまり変色が抑制される。よって、チタン基材は、算術平均粗さＲａが最大となる方向の粗さ曲線において、算術平均粗さＲａと要素長さＲＳｍの比であるＲａ／ＲＳｍが０．００６～０．０１５であり、かつ、二乗平均平方根傾斜ＲΔｑが０．１５０～０．２８０であることが好ましい。Ｒａ／ＲＳｍの下限は、より好ましくは、０．００７である。また、ＲΔｑは、より好ましくは、０．１９０以上である。ＲΔｑが０．１９０～０．０２８０になると、変色促進試験の色差が６以下となり、さらに高い効果が得られる。 If Ra/RSm is 0.006 to 0.015 and the root mean square slope RΔq of the roughness curve element is 0.150 to 0.280, the above effects are obtained by superimposing the titanium material. discoloration is further suppressed. Furthermore, even if a titanium material having the above-mentioned surface condition grows an oxide film of several tens of nanometers on its surface, a change in color tone, that is, discoloration, is suppressed. Therefore, for the titanium base material, in the roughness curve in the direction where the arithmetic mean roughness Ra is maximum, Ra/RSm, which is the ratio of the arithmetic mean roughness Ra to the element length RSm, is 0.006 to 0.015. , and the root mean square slope RΔq is preferably 0.150 to 0.280. The lower limit of Ra/RSm is more preferably 0.007. Moreover, RΔq is more preferably 0.190 or more. When RΔq is 0.190 to 0.0280, the color difference in the discoloration acceleration test becomes 6 or less, and even higher effects can be obtained.
　算術平均粗さＲａおよび輪郭曲線要素の平均長さＲＳｍは、上記のとおりＲａ／ＲＳｍが０．００６～０．０１５であることが好ましいが、算術平均粗さＲａは０．７００～３．０μｍ、輪郭曲線要素の平均長さＲＳｍは、６０～３００μｍであることがより好ましい。算術平均粗さＲａを０．７００～３．０μｍとすること、および、輪郭曲線要素の平均長さＲＳｍを６０～３００μｍとすることは、後述する製造方法にて工業的に比較的容易に実現できる。 As for the arithmetic mean roughness Ra and the mean length RSm of the contour curve elements, Ra/RSm is preferably 0.006 to 0.015 as described above, but the arithmetic mean roughness Ra is 0.700 to 3.0 μm. , the average length RSm of the contour curve elements is more preferably 60 to 300 μm. Setting the arithmetic mean roughness Ra to 0.700 to 3.0 μm and setting the average length RSm of the contour curve elements to 60 to 300 μm can be achieved industrially relatively easily using the manufacturing method described below. can.
［クルトシスＲｋｕ：３超］
　クルトシスＲｋｕは、振幅分布曲線の鋭さを表す指標である。図７は、クルトシスＲｋｕを説明するための図である。なお、図７は、宮下勤、「もう一度復習したい表面粗さ」、精密工学会誌、公益社団法人　精密工学会、Ｖｏｌ．７３，Ｎｏ．２、２００７年、ｐ．２０５に掲載された図である。クルトシスＲｋｕは、二乗平均平方根高さＲｑの四乗によって無次元した基準長さにおいて、Ｚｊの四乗平均を表す。 [Kurtosis Rku: over 3]
Kurtosis Rku is an index representing the sharpness of the amplitude distribution curve. FIG. 7 is a diagram for explaining kurtosis Rku. Furthermore, Figure 7 is based on Tsutomu Miyashita, "Surface roughness that I would like to review again," Journal of the Japan Society for Precision Engineering, Japan Society for Precision Engineering, Vol. 73, No. 2, 2007, p. This is a diagram published in 205. The kurtosis Rku represents the fourth root mean of Zj in a dimensionless reference length determined by the fourth power of the root mean square height Rq.
Figure JPOXMLDOC01-appb-M000005
Figure JPOXMLDOC01-appb-M000005
　Ｚｊは粗さ曲線においてｊ番目測定点の高さである。Ｒｑは、二乗平均平方根高さであり、下記式（６）で表される。 Zj is the height of the jth measurement point on the roughness curve. Rq is the root mean square height and is expressed by the following formula (6).
Figure JPOXMLDOC01-appb-M000006
Figure JPOXMLDOC01-appb-M000006
　クルトシスＲｋｕは、高さ分布の鋭さを示す指標であり、クルトシスＲｋｕが３である場合、図７に示されるように、高さ分布が正規分布であり、クルトシスＲｋｕが３未満で値が小さくなるに伴い、表面が平坦になり、クルトシスＳｋｕが３を超えて値が大きくなるに伴い、チタン材の表面に鋭い山や谷が多くなる。 Kurtosis Rku is an index indicating the sharpness of the height distribution, and when Kurtosis Rku is 3, the height distribution is a normal distribution as shown in FIG. 7, and when Kurtosis Rku is less than 3, the value becomes small. As the kurtosis Sku increases beyond 3, the surface becomes flat, and as the value of the kurtosis Sku increases beyond 3, sharp peaks and valleys increase on the surface of the titanium material.
　算術平均粗さＲａが最大となる方向の粗さ曲線において、チタン基材のクルトシスＲｋｕが３超であることが好ましい。クルトシスＲｋｕが３超であると、チタン基材の表面の凹凸が鋭く、凹凸が鋭い表面では、チタン基材の表面で反射する光において、干渉色が顕在化する正反射の成分がより一層抑制されることとなる。その結果、酸化皮膜厚さが増加したとしても、干渉色が、より一層目立ちにくくなるため、チタン材の変色がより一層抑制される。 In the roughness curve in the direction where the arithmetic mean roughness Ra is maximum, it is preferable that the kurtosis Rku of the titanium base material is greater than 3. When the kurtosis Rku is more than 3, the surface of the titanium base material has sharp irregularities, and on a surface with sharp irregularities, the specular reflection component in which interference colors become apparent in the light reflected on the surface of the titanium base material is further suppressed. It will be done. As a result, even if the oxide film thickness increases, the interference color becomes even less noticeable, and the discoloration of the titanium material is further suppressed.
［スキューネスＲｓｋ：－０．５超］
　スキューネスＲｓｋは、ひずみ度とも呼ばれ、表面の凹凸の鋭さを表す指標である。スキューネスＲｓｋは、二乗平均平方根高さＲｑの三乗によって無次元化した基準長さにおけるＺ（ｘ）三乗平均を表したものであり、下記式（７）で表される。 [Skewness Rsk: -0.5 or more]
The skewness Rsk is also called the degree of distortion and is an index representing the sharpness of surface irregularities. The skewness Rsk represents the root mean cube of Z(x) at the reference length, which is made dimensionless by the cube of the root mean square height Rq, and is expressed by the following formula (7).
Figure JPOXMLDOC01-appb-M000007
Figure JPOXMLDOC01-appb-M000007
　上記式（７）中、Ｎは、測定点数であり、Ｚｊは粗さ曲線においてｊ番目測定点の高さである。 In the above formula (7), N is the number of measurement points, and Zj is the height of the jth measurement point on the roughness curve.
　粗さ曲線において、谷長さが山長さよりも大きい場合、スキューネスＲｓｋは０より大きくなる。言い換えると、スキューネスＲｓｋが０より大きいと粗さ曲線の平均線において凹部の割合が高い。つまり、粗さ曲線における山（凸部）の先端が鋭利に尖り、かつ谷（凹部）末端が広幅となる。粗さ曲線の平均線とは、カットオフ波長λｃによって遮断される長波長成分を表す曲線を言う。
　一方、谷長さが山長さよりも小さい場合、スキューネスＲｓｋは０より小さくなる。言い換えると、スキューネスＲｓｋは０より小さいと粗さ曲線の平均線において凹部の割合が高い。つまり、粗さ曲線における山（凸部）の先端が広幅となり、かつ谷（凹部）末端が鋭利に尖る。
　スキューネスＲｓｋが０であると、粗さ曲線における凹凸の形状が平均面に対して対称である。 In the roughness curve, when the valley length is greater than the peak length, the skewness Rsk is greater than 0. In other words, when the skewness Rsk is greater than 0, the proportion of concave portions in the average line of the roughness curve is high. That is, the tips of the peaks (convex portions) in the roughness curve are sharply pointed, and the ends of the valleys (concave portions) are wide. The average line of the roughness curve refers to a curve representing the long wavelength component cut off by the cutoff wavelength λc.
On the other hand, when the valley length is smaller than the peak length, the skewness Rsk is smaller than zero. In other words, when the skewness Rsk is smaller than 0, the proportion of concave portions in the average line of the roughness curve is high. That is, the tips of the peaks (convex portions) in the roughness curve are wide, and the ends of the valleys (concave portions) are sharply pointed.
When the skewness Rsk is 0, the shape of the unevenness in the roughness curve is symmetrical with respect to the average surface.
　算術平均粗さＲａが最大となる方向の粗さ曲線において、チタン基材のスキューネスＲｓｋが－０．５超であることが好ましい。スキューネスＲｓｋが－０．５超であると、粗さ曲線における山（凸部）の先端が尖り、光源に近い方、つまり山（凸部）にて、チタン基材表面で反射する光がより一層散乱されやすくなり、変色がより一層抑制される。光源から遠い方、つまり谷（凸部）は、山（凸部）によるシャドー効果があるために変色の原因である干渉色が見えにくくなるため、山（凸部）よりも影響しにくいと推定される。 In the roughness curve in the direction where the arithmetic mean roughness Ra is maximum, the skewness Rsk of the titanium base material is preferably greater than -0.5. When the skewness Rsk is more than -0.5, the tips of the peaks (convex parts) in the roughness curve become sharp, and the light reflected on the titanium base material surface becomes more sharp on the side closer to the light source, that is, at the peaks (protrusions). It becomes more easily scattered and discoloration is further suppressed. The area far from the light source, that is, the valley (convex part), is estimated to be less affected than the peak (convex part) because the shadow effect caused by the peak (convex part) makes it difficult to see the interference color that causes discoloration. be done.
　ここまで、本実施形態に係るチタン材について説明した。本実施形態に係るチタン材の厚さは、例えば、０．２ｍｍ以上であってもよいし、０．３ｍｍ以上であってもよい。また、本実施形態に係るチタン材の厚さは、特段制限されず、例えば、５．０ｍｍ以下であってもよいし、３．０ｍｍ以下または２．０ｍｍ以下であってもよい。 Up to this point, the titanium material according to this embodiment has been described. The thickness of the titanium material according to this embodiment may be, for example, 0.2 mm or more, or 0.3 mm or more. Further, the thickness of the titanium material according to this embodiment is not particularly limited, and may be, for example, 5.0 mm or less, 3.0 mm or less, or 2.0 mm or less.
　本実施形態に係るチタン材では、表面から、グロー放電分光分析法によって前記表面から厚さ方向に測定された酸素濃度が最大値の１／３である位置までの範囲の平均窒素濃度および平均炭素濃度がそれぞれ１４．０原子％以下、平均水素濃度が３０．０原子％以下であり、前記表面において入射角が０．３度である平行ビーム法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数と、板厚中央において集中法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数との差が０．０１５Å以下である。これにより、本実施形態に係るチタン材は、従来のチタン材よりも長期に亘って変色が抑制され、耐変色性に優れたものとなる。 In the titanium material according to this embodiment, the average nitrogen concentration and the average carbon concentration in the range from the surface to the position where the oxygen concentration measured in the thickness direction from the surface by glow discharge spectrometry is 1/3 of the maximum value. α-phase Ti determined by X-ray diffraction measurement using a parallel beam method with a concentration of 14.0 atomic % or less, an average hydrogen concentration of 30.0 atomic % or less, and an incident angle of 0.3 degrees on the surface. The difference between the c-axis lattice constant of the α-phase Ti and the c-axis lattice constant of α-phase Ti determined by X-ray diffraction measurement using the focusing method at the center of the plate thickness is 0.015 Å or less. As a result, the titanium material according to the present embodiment suppresses discoloration for a longer period of time than conventional titanium materials, and has excellent discoloration resistance.
　また、酸化皮膜におけるＸ線光電子分光法で分析したときの窒化物由来の窒素濃度の最大値が２．０～１０．０原子％であり、前記酸化皮膜における前記窒化物由来の窒素濃度が最大値を示す位置が、ＳｉＯ２のスパッタリング速度で換算したときに、前記酸化皮膜の表面から２～１０ｎｍの範囲に存在し、前記チタン基材における前記酸化皮膜との界面近傍に存在する前記窒化物由来の窒素の濃度が、前記酸化皮膜における前記窒化物由来の窒素濃度の最大値未満且つ７．０原子％以下であり、前記酸化皮膜における前記窒化物由来の前記窒素濃度の最大値が、前記酸化皮膜における前記窒化物由来の前記窒素濃度が最大となる位置の炭化物由来の炭素濃度以上であれば、高温かつ酸性環境下においても耐変色性に優れる。そして、高温かつ酸性環境下においても耐変色性を優れるチタン材は、長期に亘る変色をより一層抑制することが可能である。 Further, the maximum value of the nitrogen concentration derived from nitrides when analyzed by X-ray photoelectron spectroscopy in the oxide film is 2.0 to 10.0 at%, and the maximum value of the nitrogen concentration derived from the nitrides in the oxide film is 2.0 to 10.0 at%. The nitride is present in a range of 2 to 10 nm from the surface of the oxide film, and the nitride is present in the vicinity of the interface with the oxide film in the titanium base material, when converted to the SiO 2 sputtering rate. The concentration of nitrogen derived from the nitride in the oxide film is less than the maximum value of the nitrogen concentration derived from the nitride and 7.0 atomic % or less, and the maximum value of the nitrogen concentration derived from the nitride in the oxide film is If the concentration of nitrogen derived from the nitride in the oxide film is equal to or higher than the carbon concentration derived from the carbide at the maximum position, the color fastness is excellent even under high temperature and acidic environments. Titanium material, which has excellent discoloration resistance even under high temperature and acidic environments, can further suppress discoloration over a long period of time.
（チタン材の製造方法）
　本実施形態に係るチタン材の製造方法の一例について説明する。ただし、本実施形態に係るチタン材は、以下に説明する製造方法によって製造されたものに限定されるものではない。また、外装材等の建材に使用される純チタンおよびチタン合金は、板形状である場合が多いため、以下では、板形状のチタン材の製造方法の一例を説明する。 (Method for manufacturing titanium material)
An example of a method for manufacturing a titanium material according to this embodiment will be described. However, the titanium material according to this embodiment is not limited to that manufactured by the manufacturing method described below. Moreover, since pure titanium and titanium alloys used for building materials such as exterior materials are often plate-shaped, an example of a method for producing plate-shaped titanium materials will be described below.
　チタン材は、素材である純チタンまたはチタン合金が冷間圧延によって圧延された後、焼鈍処理、および冷却処理が施され、製造される。 A titanium material is manufactured by cold rolling a raw material of pure titanium or a titanium alloy, and then subjecting it to an annealing treatment and a cooling treatment.
　冷間圧延に供するチタン素材には、公知の方法で製造されたものを用いてよい。例えば、スポンジチタンや合金元素を添加するための母合金等を原料として、真空アーク溶解法や電子ビーム溶解法またはプラズマ溶解法等のハース溶解法等の各種溶解法により、上記の成分を有する純チタンまたはチタン合金のインゴットを作製する。次に、得られたインゴットを必要に応じて分塊、熱間鍛造してスラブとする。その後、スラブを熱間圧延して上記の組成を有する純チタンまたはチタン合金の熱延コイルとする。
　なお、スラブには、必要に応じて洗浄処理、切削等の前処理が施されていてもよい。また、ハース溶解法で熱延可能な矩形とした場合は、熱間鍛造等を行わず熱間圧延に供してもよい。 The titanium material to be subjected to cold rolling may be produced by a known method. For example, using sponge titanium or a master alloy for adding alloying elements as a raw material, a pure material containing the above components is produced by various melting methods such as vacuum arc melting, electron beam melting, or Haas melting such as plasma melting. A titanium or titanium alloy ingot is produced. Next, the obtained ingot is bloomed and hot forged to form a slab, if necessary. Thereafter, the slab is hot rolled into a hot rolled coil of pure titanium or titanium alloy having the above composition.
Note that the slab may be subjected to pretreatment such as cleaning treatment and cutting as necessary. Further, when the rectangular shape can be hot rolled by the hearth melting method, hot rolling may be performed without performing hot forging or the like.
　次いで、熱延コイルを冷間圧延に供する。冷間圧延には潤滑油が使用されるが、使用される潤滑油は、焼鈍処理時にチタン材の表面の炭素濃度を高める原因になる場合がある。そのため、好ましくは、焼鈍処理を施す前にアルカリ脱脂、ダルロールを用いた圧延であるダル圧延、コイルグラインダ、または研磨等によってチタン素材の表面に存在する油分が除去される。なお、チタン素材表面に潤滑油が塗布されて冷間圧延すると、メカノケミカル反応により、チタン素材の表面に炭素が含まれることになる。最終焼鈍処理に供する冷チタン素材は、適宜、酸洗や焼鈍がされていてもよい。 Next, the hot rolled coil is subjected to cold rolling. Lubricating oil is used in cold rolling, but the lubricating oil used may cause an increase in the carbon concentration on the surface of the titanium material during annealing. Therefore, before annealing, oil present on the surface of the titanium material is preferably removed by alkaline degreasing, dull rolling using dull rolls, coil grinder, polishing, or the like. Note that when lubricating oil is applied to the surface of a titanium material and cold rolling is performed, carbon is contained on the surface of the titanium material due to a mechanochemical reaction. The cold titanium material to be subjected to the final annealing treatment may be pickled or annealed as appropriate.
　冷間圧延後のチタン素材または油分除去処理後のチタン素材に対して、最終焼鈍処理を施す。最終焼鈍処理は、一般には、冷間圧延によってチタン素材である純チタンまたはチタン合金に導入された歪みを低減し、当該チタン素材を軟化させる工程である。本実施形態に係るチタン材の製造においては、最終焼鈍処理およびそれに引き続く冷却処理は、チタン材の表層部の平均窒素濃度および平均炭素濃度、平均水素濃度、チタン材の表層部におけるα相のＴｉのｃ軸の格子定数、並びに酸化皮膜の厚さを制御することを目的とした工程である。最終焼鈍処理の温度を高めることにより、不純物に起因した、チタン材の表層部の窒素および炭素が厚さ方向に拡散して、チタン材の表層部の平均窒素濃度および平均炭素濃度が低下すると考えられる。チタン材の表層部の平均水素濃度、およびチタン材の表層部におけるα相のＴｉのｃ軸の格子定数は、最終焼鈍処理の真空度を高めることにより、低下すると考えられる。そのため、最終焼純処理は、真空雰囲気にした後の不活性ガス（窒素ガスを除く）雰囲気中あるいはそのまま真空中で施される。以下に最終焼鈍処理の加熱温度および最終焼鈍処理の雰囲気について説明する。ここで不活性ガスとは、チタンに対しての不活性なガスを指し、アルゴン、ヘリウム、ネオンをいう。 A final annealing treatment is performed on the titanium material after cold rolling or the titanium material after oil removal treatment. The final annealing treatment is generally a process of reducing the strain introduced into the titanium material, pure titanium or titanium alloy, by cold rolling and softening the titanium material. In the production of the titanium material according to the present embodiment, the final annealing treatment and the subsequent cooling treatment include the average nitrogen concentration, average carbon concentration, and average hydrogen concentration in the surface layer of the titanium material, and the α-phase Ti in the surface layer of the titanium material. This process aims to control the c-axis lattice constant and the thickness of the oxide film. It is believed that by increasing the temperature of the final annealing treatment, nitrogen and carbon in the surface layer of the titanium material caused by impurities will diffuse in the thickness direction, reducing the average nitrogen concentration and average carbon concentration in the surface layer of the titanium material. It will be done. It is thought that the average hydrogen concentration in the surface layer of the titanium material and the c-axis lattice constant of α-phase Ti in the surface layer of the titanium material are reduced by increasing the degree of vacuum in the final annealing treatment. Therefore, the final sintering treatment is performed in an inert gas (excluding nitrogen gas) atmosphere after creating a vacuum atmosphere, or directly in a vacuum. The heating temperature of the final annealing treatment and the atmosphere of the final annealing treatment will be explained below. Here, the inert gas refers to a gas that is inert to titanium, and includes argon, helium, and neon.
　最終焼鈍処理の加熱温度（焼鈍温度）は、チタン材の表層部の平均窒素濃度および平均炭素濃度の低減という観点から、６３０℃以上である。焼鈍温度は、チタン材の表層部の平均炭素濃度の低減という観点から、好ましくは６５０℃以上である。焼鈍温度の上限は特に設けないが、製造コストの観点から７５０℃以下が好ましい。ここで言う焼鈍温度は、焼鈍処理に使用される加熱炉内の温度であり、加熱炉に設置された熱電対を用いて測定される。焼鈍時間は、チタン材の表層部の平均窒素濃度および平均炭素濃度の低減という観点から、５時間以上が好ましい。焼鈍時間は、より好ましくは、１０時間以上である。焼鈍時間は、冷延ままのチタン材は焼鈍できることから３時間以上であってもよい。一方、焼鈍時間は、生産性の観点からは、好ましくは、焼鈍時間は４８時間以下である。また、焼鈍時間が１０時間超であると、結晶粒径が粗大になり過ぎて引張強度の低下や加工による皺等の不具合を招く場合がある。したがって、焼鈍時間は、引張強度の維持等の観点からは、１０時間以下であることが好ましい。なお、ここで言う焼鈍時間は、チタン材を内部に有する加熱炉内の温度が焼鈍温度に維持されている時間である。 The heating temperature (annealing temperature) of the final annealing treatment is 630° C. or higher from the viewpoint of reducing the average nitrogen concentration and average carbon concentration in the surface layer portion of the titanium material. The annealing temperature is preferably 650° C. or higher from the viewpoint of reducing the average carbon concentration in the surface layer of the titanium material. Although there is no particular upper limit to the annealing temperature, it is preferably 750° C. or lower from the viewpoint of manufacturing costs. The annealing temperature referred to here is the temperature inside the heating furnace used for annealing treatment, and is measured using a thermocouple installed in the heating furnace. The annealing time is preferably 5 hours or more from the viewpoint of reducing the average nitrogen concentration and average carbon concentration in the surface layer portion of the titanium material. The annealing time is more preferably 10 hours or more. The annealing time may be 3 hours or more because the as-cold rolled titanium material can be annealed. On the other hand, from the viewpoint of productivity, the annealing time is preferably 48 hours or less. Further, if the annealing time exceeds 10 hours, the crystal grain size becomes too coarse, which may cause problems such as a decrease in tensile strength and wrinkles due to processing. Therefore, from the viewpoint of maintaining tensile strength, etc., the annealing time is preferably 10 hours or less. Note that the annealing time referred to here is the time during which the temperature in the heating furnace containing the titanium material is maintained at the annealing temperature.
　最終焼鈍処理は、真空雰囲気、不活性ガス雰囲気（窒素ガスを除く）、または真空雰囲気にした後に窒素を除く不活性ガスを導入した不活性ガス雰囲気で行われる。真空雰囲気の真空度は、例えば、１.０×１０-２Ｐａ以下である。不活性ガス雰囲気は、好ましくは希ガス雰囲気であり、より好ましくはＡｒ雰囲気である。最終焼鈍処理における不活性ガス雰囲気にする前の真空度は、チタン材の表層部におけるα相のＴｉのｃ軸の格子定数の増大の抑制、チタン材の表層部の平均水素濃度および平均窒素濃度の低減という観点から、１.０×１０-２Ｐａ以下であることが好ましい。最終焼鈍処理における不活性ガス雰囲気にする前の真空度は、チタン材の表層部の平均水素濃度の低減という観点から、より好ましくは、５.０×１０-３Ｐａ以下である。また、不活性ガス雰囲気は、加熱炉内を、例えば、９９．９９体積％以上のＡｒを含有する雰囲気とすればよい。不活性雰囲気は、９９．９９体積％以上のＨｅ（ヘリウム）を含有する雰囲気であってもよい。最終焼鈍処理の加熱の開始前までに加熱炉内を真空雰囲気にした後に不活性ガス雰囲気にしてもよく、加熱の開始前に加熱炉内を真空雰囲気にし、加熱の開始から冷却の開始までの間に加熱炉内を真空雰囲気から不活性ガス雰囲気に変更してもよい。 The final annealing treatment is performed in a vacuum atmosphere, an inert gas atmosphere (excluding nitrogen gas), or an inert gas atmosphere in which an inert gas excluding nitrogen is introduced after creating a vacuum atmosphere. The degree of vacuum of the vacuum atmosphere is, for example, 1.0×10 −2 Pa or less. The inert gas atmosphere is preferably a rare gas atmosphere, more preferably an Ar atmosphere. The degree of vacuum before creating an inert gas atmosphere in the final annealing treatment is to suppress the increase in the c-axis lattice constant of α-phase Ti in the surface layer of the titanium material, and to suppress the average hydrogen concentration and average nitrogen concentration in the surface layer of the titanium material. From the viewpoint of reducing the pressure, it is preferably 1.0×10 −2 Pa or less. The degree of vacuum before creating an inert gas atmosphere in the final annealing treatment is more preferably 5.0×10 −3 Pa or less from the viewpoint of reducing the average hydrogen concentration in the surface layer portion of the titanium material. Further, the inert gas atmosphere in the heating furnace may be, for example, an atmosphere containing 99.99% by volume or more of Ar. The inert atmosphere may be an atmosphere containing 99.99% by volume or more of He (helium). The inside of the heating furnace may be made into a vacuum atmosphere before the start of heating for the final annealing treatment, and then an inert gas atmosphere may be created. In the meantime, the inside of the heating furnace may be changed from a vacuum atmosphere to an inert gas atmosphere.
　最終焼鈍処理を、真空雰囲気、または真空雰囲気にした後に窒素を除く不活性ガスを導入した不活性ガス雰囲気（窒素を除く）で、上述の焼鈍温度と焼鈍時間にて行うことで、チタン材の表面では酸素、窒素、炭素、水素が低い状態が形成される。最終焼鈍処理において、このような、チタン材の表面を清浄度の高い表面状態にすることで、その後の冷却処理時に大気、窒素ガス雰囲気、窒素ガスを１０％以上含む不活性ガス雰囲気に開放し、これらの雰囲気に含まれる窒素によって酸化皮膜内に所定の量の窒化物を生成することができる。最終焼鈍処理にて冷却した後に大気に開放したチタン材では、改めて窒素を含む雰囲気に加熱しても、酸化皮膜内に所定の窒化物を生成することはできない。 By performing the final annealing treatment in a vacuum atmosphere, or in an inert gas atmosphere (excluding nitrogen) in which an inert gas excluding nitrogen is introduced after creating a vacuum atmosphere, at the annealing temperature and time described above, titanium materials can be At the surface, conditions with low levels of oxygen, nitrogen, carbon, and hydrogen are formed. By making the surface of the titanium material highly clean in the final annealing treatment, it can be exposed to the atmosphere, a nitrogen gas atmosphere, or an inert gas atmosphere containing 10% or more nitrogen gas during the subsequent cooling treatment. A predetermined amount of nitride can be generated in the oxide film by the nitrogen contained in these atmospheres. In a titanium material that has been cooled in the final annealing treatment and then exposed to the atmosphere, even if it is heated again to an atmosphere containing nitrogen, the desired nitride cannot be generated in the oxide film.
　焼鈍雰囲気の窒素濃度は０．００５体積％以下の不活性ガスである。なお、一般工業用の純ガスでは、不純物のうち窒素は半分以下であることから、上述の不活性ガスを用いた本実施形態における焼鈍処理の雰囲気として十分な純度である。 The nitrogen concentration in the annealing atmosphere is an inert gas of 0.005% by volume or less. Note that in general industrial pure gas, nitrogen accounts for less than half of the impurities, so the purity is sufficient as the atmosphere for the annealing process in this embodiment using the above-mentioned inert gas.
　最終焼鈍処理の雰囲気は、焼鈍処理後のチタン材にテンパーカラーが付かない温度以下、例えば、３００℃以下の温度まで維持される。焼鈍雰囲気は、室温に冷却されるまで維持されてもよいし、３００℃以下の温度で、加熱炉内を大気などに開放してもよい。 The atmosphere for the final annealing treatment is maintained at a temperature below which temper color does not form on the titanium material after the annealing treatment, for example, at a temperature below 300°C. The annealing atmosphere may be maintained until it is cooled to room temperature, or the inside of the heating furnace may be opened to the atmosphere at a temperature of 300° C. or lower.
　最終焼鈍処理後、チタン素材を冷却する。冷却雰囲気は、例えば、冷却開始当初は焼鈍雰囲気と同様の雰囲気であり、加熱炉内の温度が３００℃以下では、窒素ガスで構成される雰囲気、窒素を１０体積％以上含むアルゴンもしくはヘリウムの混合雰囲気、または大気であればよい。 After the final annealing treatment, the titanium material is cooled. The cooling atmosphere is, for example, an atmosphere similar to the annealing atmosphere at the beginning of cooling, and when the temperature in the heating furnace is below 300°C, an atmosphere consisting of nitrogen gas, or a mixture of argon or helium containing 10% by volume or more of nitrogen. Any atmosphere or air may be used.
　最終焼鈍処理後の冷却速度は、特段制限されない。ただし、開放される３００℃以下では、酸化皮膜に存在する窒化物由来の窒素量を所定範囲とするために、以降で述べる条件とした方が好ましい。また、冷却時のチタン材の熱収縮による形状の乱れを抑制する意味で、開放まで（３００℃以下まで）の冷却速度は、好ましくは５０℃／分以下、より好ましくは３０℃／分以下であり、さらには１トン以上の大型のチタン材を冷却する場合には、１℃／分が好ましい。 The cooling rate after the final annealing treatment is not particularly limited. However, at a temperature below 300° C. where the temperature is open, in order to keep the amount of nitrogen derived from nitrides present in the oxide film within a predetermined range, it is preferable to use the conditions described below. In addition, in order to suppress distortion of the shape due to thermal contraction of the titanium material during cooling, the cooling rate until opening (to 300°C or less) is preferably 50°C/min or less, more preferably 30°C/min or less. Furthermore, when cooling a large titanium material weighing 1 ton or more, 1° C./min is preferable.
　最終焼鈍処理後の冷却では、加熱炉内の温度が３００℃以下の温度となった時点で、加熱炉内に窒素ガスを導入または加熱炉内を大気に開放して、加熱炉内を１０体積％以上の窒素を含有する窒素雰囲気にすることが好ましい。酸化皮膜に存在する窒化物由来の窒素量は、温度と雰囲気に加えてチタン材表面の清浄度によって変化する。これは、チタン素材の表面に存在する微量の炭素、酸素、水素、窒素が競合してチタン材表面にて反応するが、どのような反応が優先的に起きるかによって窒素とチタンの反応量が変化し、それに伴い窒化物の生成量も変化するためであると考えられる。しかしながら、雰囲気を変更するとき（開放するとき）の温度が３００℃以下であれば、チタンと窒素との反応が十分に起き、かつ、生成する窒化物が過剰になることもない。そのため、焼鈍処理に引き続く冷却処理により、酸化皮膜に存在する窒化物由来の窒素濃度の最大値を２．０～１０．０原子％にすることができる。一方、雰囲気を変更するときの温度が２００℃未満では、酸化皮膜の窒化物由来の窒素含有量が２．０原子％未満になる。これは、温度が低いと、窒素とチタンの反応が緩慢になるためである。上記温度は、好ましくは、２５０℃以上であり、より好ましくは、２８０℃以上である。 In cooling after the final annealing process, when the temperature inside the heating furnace reaches 300°C or less, nitrogen gas is introduced into the heating furnace or the inside of the heating furnace is opened to the atmosphere, and the inside of the heating furnace is heated to 10 vol. It is preferable to use a nitrogen atmosphere containing % or more of nitrogen. The amount of nitrogen derived from nitrides present in the oxide film varies depending on the temperature and atmosphere as well as the cleanliness of the titanium material surface. This is because the trace amounts of carbon, oxygen, hydrogen, and nitrogen that exist on the surface of the titanium material compete and react on the surface of the titanium material, but the amount of reaction between nitrogen and titanium depends on which reaction occurs preferentially. This is thought to be because the amount of nitrides produced changes accordingly. However, if the temperature when changing the atmosphere (when opening the atmosphere) is 300° C. or lower, the reaction between titanium and nitrogen will occur sufficiently, and nitrides will not be produced in excess. Therefore, by cooling treatment subsequent to annealing treatment, the maximum concentration of nitrogen derived from nitrides present in the oxide film can be set to 2.0 to 10.0 at.%. On the other hand, if the temperature when changing the atmosphere is less than 200° C., the nitrogen content derived from nitrides in the oxide film will be less than 2.0 at %. This is because the reaction between nitrogen and titanium becomes slower at lower temperatures. The above temperature is preferably 250°C or higher, more preferably 280°C or higher.
　加熱炉内を窒素雰囲気にした後、２００℃に達するまでの冷却時間を１．５時間以上とすることが好ましく、２．０時間以上とすることがより好ましい。加熱炉内を窒素雰囲気にした後、２００℃に達するまでの冷却時間を１．５時間以上とすることで、酸化皮膜におけるＸ線光電子分光法で分析したときの窒化物由来の窒素濃度の最大値が２．０～１０．０原子％となり、かつ、前記酸化皮膜における前記窒化物由来の窒素濃度が最大値を示す位置が、ＳｉＯ２のスパッタリング速度で換算したときに、前記酸化皮膜の表面から２～１０ｎｍの範囲に存在することになる。 After the inside of the heating furnace is made into a nitrogen atmosphere, the cooling time until reaching 200° C. is preferably 1.5 hours or more, and more preferably 2.0 hours or more. After creating a nitrogen atmosphere in the heating furnace, by setting the cooling time to 200°C for 1.5 hours or more, the maximum concentration of nitrogen derived from nitrides when analyzed by X-ray photoelectron spectroscopy in the oxide film is reduced. value is 2.0 to 10.0 atomic %, and the position where the nitrogen concentration derived from the nitride in the oxide film has the maximum value is the surface of the oxide film when converted by the sputtering rate of SiO 2 It exists in the range of 2 to 10 nm from .
　なお、冷却処理後のチタン材に対して、圧下率５％以下でダルロールを用いた圧延を含む冷間圧延を施しても、本実施形態に係るチタン材の特徴は維持される。 Note that even if the titanium material after the cooling treatment is subjected to cold rolling including rolling using dull rolls at a reduction rate of 5% or less, the characteristics of the titanium material according to the present embodiment are maintained.
　本実施形態に係るチタン材の製造方法では、チタン素材の表面をＪＩＳ　Ｒ　６００１－２：２０１７に準拠した＃３２０以下の番手の粒度分布を有する研磨微粉を用いて研磨する研磨工程と、表面粗さＲａが０．５μｍ以上の圧延ロールを用いて、総圧下率が０．１０％以上となるようにチタン素材を圧下するダル圧延工程と、を有することが好ましい。上記研磨工程は上記最終焼鈍処理前に実施され、上記ダル圧延工程は、上記最終焼鈍処理後に行われる。上記の研磨工程およびダル圧延工程により、チタン基材表面のＲａ／ＲＳｍが０．００６～０．０１５となり、かつ、粗さ曲線要素の二乗平均平方根傾斜ＲΔｑが０．１５０～０．２８０となる。以下に、上記研磨工程およびダル圧延工程を説明する。 The method for manufacturing a titanium material according to the present embodiment includes a polishing step of polishing the surface of the titanium material using abrasive fine powder having a particle size distribution of #320 or less in accordance with JIS R 6001-2:2017, and It is preferable to include a dull rolling step in which the titanium material is rolled down using a rolling roll having an Ra of 0.5 μm or more so that the total rolling reduction is 0.10% or more. The polishing step is performed before the final annealing treatment, and the dull rolling step is performed after the final annealing treatment. Through the above polishing process and dull rolling process, the Ra/RSm of the titanium base material surface becomes 0.006 to 0.015, and the root mean square slope RΔq of the roughness curve element becomes 0.150 to 0.280. . Below, the polishing process and dull rolling process will be explained.
［研磨工程］
　本工程では、チタン素材の表面をＪＩＳ　Ｒ　６００１－２：２０１７に準拠した＃３２０以下の番手の粒度分布を有する研磨微粉を用いて研磨する。チタン素材の表面を研磨する手段は特段制限されず、例えば、ブラシロールやコイルグラインダ等、公知の手段を用いることができる。 [Polishing process]
In this step, the surface of the titanium material is polished using abrasive fine powder having a particle size distribution of #320 or less in accordance with JIS R 6001-2:2017. The means for polishing the surface of the titanium material is not particularly limited, and for example, known means such as a brush roll or a coil grinder can be used.
　例えば、コイルグラインダを用いる場合、以下の方法で板コイル状のチタン素材の表面を研磨する。コイルライン研磨機にて、＃３２０以下、例えば＃３２０、＃２４０、＃１００、＃８０等の番手の研磨ベルトを用いてチタン材を研磨する。研磨ベルトに用いられる研磨微粉は、好ましくは、＃１００以下の番手のものである。より、均一な研磨表面を得るために、同一の番手、あるいは番手を変えて、複数回の研磨を施す場合がある。 For example, when using a coil grinder, the surface of a plate coil-shaped titanium material is polished by the following method. The titanium material is polished using a coil line polishing machine using a polishing belt with a count of #320 or less, for example, #320, #240, #100, #80, etc. The abrasive fine powder used in the abrasive belt preferably has a count of #100 or less. In order to obtain a more uniform polished surface, polishing may be performed multiple times with the same or different grits.
　研磨工程に供するチタン素材には、公知の方法で製造されたものを用いてよい。例えば、スポンジチタンや合金元素を添加するための母合金等を原料として、真空アーク溶解法や電子ビーム溶解法またはプラズマ溶解法等のハース溶解法等の各種溶解法により、上記の成分を有する純チタンまたはチタン合金のインゴットを作製する。次に、得られたインゴットを必要に応じて分塊、熱間鍛造してスラブとする。その後、スラブを熱間圧延して上記の組成を有する純チタンまたはチタン合金の熱延コイルとする。この熱延コイルを冷間圧延し、冷間圧延後のチタン素材に対し研磨工程を実施すればよい。研磨工程に供する冷間圧延後のチタン素材は、適宜焼鈍されていてもよい。
　なお、スラブには、必要に応じて研磨、切削等の前処理が施されていてもよい。また、ハース溶解法で熱延可能な矩形とした場合は、分塊や熱間鍛造等を行わず熱間圧延に供してもよい。
　冷間圧延条件も特段制限されず、適宜所望の厚さ、特性等が得られる条件で行えばよい。 The titanium material used in the polishing process may be manufactured by a known method. For example, using sponge titanium or a master alloy for adding alloying elements as a raw material, a pure material containing the above components is produced by various melting methods such as vacuum arc melting, electron beam melting, or Haas melting such as plasma melting. A titanium or titanium alloy ingot is produced. Next, the obtained ingot is bloomed and hot forged to form a slab, if necessary. Thereafter, the slab is hot rolled into a hot rolled coil of pure titanium or titanium alloy having the above composition. This hot-rolled coil may be cold-rolled, and the titanium material after cold-rolling may be subjected to a polishing process. The cold-rolled titanium material to be subjected to the polishing step may be appropriately annealed.
Note that the slab may be subjected to pretreatment such as polishing and cutting as necessary. Further, when a rectangular shape that can be hot rolled by the hearth melting method, hot rolling may be performed without performing blooming, hot forging, or the like.
Cold rolling conditions are also not particularly limited, and may be carried out under conditions that allow desired thickness, properties, etc. to be obtained as appropriate.
［ダル圧延工程］
　本工程では、表面の算術平均粗さＲａが０．５μｍ以上の圧延ワークロール（以降、圧延ロールと言う。）を用いてチタン素材を圧下する。上記圧延ロールを用いて、総圧下率が０．１０％以上となるようにチタン素材を圧下することで、チタン素材の表面に、より局所的な傾斜をなす凹凸が付与される。圧延ロールの表面の算術平均粗さＲａが大きすぎると、研磨工程によって事前に付与した凹凸形状が大きく変化する場合があるため、圧延ロールの表面の算術平均粗さＲａは、好ましくは２．０μｍ以下である。
　圧延ロールの表面粗さは、研磨やショットブラストで調整することができる。 [Dull rolling process]
In this step, the titanium material is rolled down using a rolling work roll (hereinafter referred to as rolling roll) whose surface has an arithmetic mean roughness Ra of 0.5 μm or more. By rolling down the titanium material using the above-mentioned rolling rolls so that the total rolling reduction ratio is 0.10% or more, more locally inclined unevenness is imparted to the surface of the titanium material. If the arithmetic mean roughness Ra of the surface of the roll is too large, the uneven shape provided in advance by the polishing process may change significantly, so the arithmetic mean roughness Ra of the surface of the roll is preferably 2.0 μm. It is as follows.
The surface roughness of the rolling roll can be adjusted by polishing or shot blasting.
　総圧下率は、局所的な傾斜をなす凹凸を付与するために０．１０％以上、好ましくはコイル全長での表面造り込みの安定性から０．２％以上とすることが好ましい。一方、前工程の研磨で形成した表面粗さを冷延で潰して必要な凹凸形状を消滅させてしまわないように、１．５％以下とすることが好ましい。また、本発明の表面特徴を得るにはこの冷延は１パスでも十分であるが、長尺のコイルにて全長をできるだけ均一な表面に仕上げる点を加味して、冷延を２パス以上の複数回で実施してよい。その点を考慮して総圧下率を規定し、複数パスの場合には、総圧下率は、初期と仕上げの板厚の差から求めた圧下率とする。 The total rolling reduction ratio is preferably 0.10% or more in order to provide locally sloped unevenness, and preferably 0.2% or more in view of the stability of the surface build-up over the entire length of the coil. On the other hand, it is preferable that the surface roughness is 1.5% or less so that the surface roughness formed by polishing in the previous step is not crushed by cold rolling and the necessary uneven shape disappears. In addition, although one pass of cold rolling is sufficient to obtain the surface characteristics of the present invention, two or more passes of cold rolling are necessary to finish the surface as uniformly as possible over the entire length using a long coil. It may be performed multiple times. The total rolling reduction rate is determined in consideration of this point, and in the case of multiple passes, the total rolling reduction rate is determined from the difference between the initial and finished plate thicknesses.
（実施例１）
　表１に示したチタン素材を０．４ｍｍの厚さに冷間圧延した後、アルカリまたは有機溶媒等を用いて脱脂し、チタン素材の表面の油分を除去した。本実施例では、ＪＩＳ　Ｈ　４６００：２０１２に準拠したＪＩＳ１種純チタン（ＡＳＴＭ　Ｇｒ．１相当）、ＪＩＳ２種純チタン（ＡＳＴＭ　Ｇｒ．２相当）、ＪＩＳ３種純チタン（ＡＳＴＭ　Ｇｒ．３相当）、ＪＩＳ４種純チタン（ＡＳＴＭ　Ｇｒ．４相当）、ＪＩＳ１１種チタン合金（ＡＳＴＭ　Ｇｒ．１１相当、Ｔｉ－０．１５Ｐｄ）、ＪＩＳ２１種チタン合金（ＡＳＴＭ　Ｇｒ．１３相当、Ｔｉ－０．５Ｎｉ－０．０５Ｒｕ）、ＪＩＳ１７種チタン合金（ＡＳＴＭ　Ｇｒ．７相当、Ｔｉ－０．０５Ｐｄ）、Ｔｉ－Ｒｕ－Ｍｍ、Ｔｉ－３Ａｌ－２．５Ｖ、Ｔｉ－５Ａｌ－１Ｆｅ、およびＪＩＳ６０種チタン合金（ＡＳＴＭ　Ｇｒ．５相当、Ｔｉ－６Ａｌ－４Ｖ）を用いた。Ｔｉ－Ｒｕ－ＭｍにおけるＭｍは、ミッシュメタルを示す。
　その後、本発明例１～２３では、各チタン素材に対し、表１に示す条件で焼鈍処理を行った。表１に示す開放温度は、各焼鈍温度で各焼鈍時間の保持が行われた後、冷却過程において炉内を開放したときの温度である。このときの温度は、熱電対を用いて測定した炉内の温度である。
　本発明例１～１３、１９～２３および比較例１～３では、表１の「真空度」に示す真空雰囲気下で加熱が開始され、冷却の開始までの間に、焼鈍炉内に９９．９９体積％以上のＡｒガスが導入された。各チタン素材が各焼鈍温度の炉内で各焼鈍時間だけ保持された後の冷却過程では、表１に示す開放温度まで各焼鈍雰囲気が維持され、開放温度まで炉内の温度が低下した時点で炉内が開放された。
　本発明例１４、１５では、Ａｒ雰囲気で加熱が開始され、炉内が開放されるまで当該Ａｒ雰囲気が維持された。
　本発明例１６～１８では、表１の「真空度」に示す真空雰囲気下で加熱が開始され、炉内が開放されるまで当該真空度が維持された。
　比較例４および比較例５では、表１に示したチタン素材を０．４ｍｍの厚さに冷間圧延した後、アルカリまたは有機溶媒等を用いて脱脂した後、最終焼鈍処理を実施せずに、硝フッ酸酸洗仕上げが行われた。 (Example 1)
The titanium materials shown in Table 1 were cold rolled to a thickness of 0.4 mm, and then degreased using an alkali or organic solvent to remove oil on the surface of the titanium materials. In this example, JIS Class 1 pure titanium (equivalent to ASTM Gr. 1), JIS Class 2 pure titanium (equivalent to ASTM Gr. 2), JIS Class 3 pure titanium (equivalent to ASTM Gr. 3), and JIS 4 are used in accordance with JIS H 4600:2012. Seed pure titanium (equivalent to ASTM Gr.4), JIS class 11 titanium alloy (equivalent to ASTM Gr.11, Ti-0.15Pd), JIS class 21 titanium alloy (equivalent to ASTM Gr.13, Ti-0.5Ni-0.05Ru) , JIS 17 grade titanium alloy (equivalent to ASTM Gr. 7, Ti-0.05Pd), Ti-Ru-Mm, Ti-3Al-2.5V, Ti-5Al-1Fe, and JIS 60 grade titanium alloy (equivalent to ASTM Gr. 5) , Ti-6Al-4V) was used. Mm in Ti-Ru-Mm represents misch metal.
Thereafter, in Examples 1 to 23 of the present invention, each titanium material was annealed under the conditions shown in Table 1. The opening temperature shown in Table 1 is the temperature when the inside of the furnace is opened in the cooling process after holding each annealing time at each annealing temperature. The temperature at this time is the temperature inside the furnace measured using a thermocouple.
In Inventive Examples 1 to 13, 19 to 23, and Comparative Examples 1 to 3, heating was started in the vacuum atmosphere shown in "Degree of Vacuum" in Table 1, and until the start of cooling, the temperature in the annealing furnace was 99. Ar gas of 99% by volume or more was introduced. In the cooling process after each titanium material is held in the furnace at each annealing temperature for each annealing time, each annealing atmosphere is maintained up to the opening temperature shown in Table 1, and when the temperature in the furnace has decreased to the opening temperature. The inside of the furnace was opened.
In Examples 14 and 15 of the present invention, heating was started in an Ar atmosphere, and the Ar atmosphere was maintained until the inside of the furnace was opened.
In Examples 16 to 18 of the present invention, heating was started under the vacuum atmosphere shown in "Degree of Vacuum" in Table 1, and the degree of vacuum was maintained until the inside of the furnace was opened.
In Comparative Example 4 and Comparative Example 5, the titanium materials shown in Table 1 were cold rolled to a thickness of 0.4 mm, degreased using an alkali or organic solvent, etc., and then subjected to no final annealing treatment. , nitric-hydrofluoric acid pickling finish was performed.
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
　表層部の平均窒素濃度、平均炭素濃度および平均水素濃度は以下の方法で求められた。Ｏ、Ｎ、Ｃ、ＨおよびＴｉについて、ＧＤＳにて分析が行われた。測定には、株式会社堀場製作所製ＪＯＢＩＮ　ＹＶＯＮ　ＧＤ－Ｐｒｏｆｉｌｅｒ２を用いた。測定の条件は３５Ｗの定電力モード、アルゴンガスの圧力は６００Ｐａ、放電範囲は直径４ｍｍとした。ＧＤＳによる測定において、測定ピッチは０．５ｎｍであった。
　上記各元素の濃度（原子％）は、上記元素の合計を１００原子％として算出された。チタン材の表面から、ＧＤＳによって厚さ方向に測定された酸素濃度が最大値の１／３である位置までの範囲をチタン材の表層部とした。平均窒素濃度、平均炭素濃度および平均水素濃度は、各測定点の窒素濃度、炭素濃度および水素濃度の数値の算術平均値とした。 The average nitrogen concentration, average carbon concentration, and average hydrogen concentration in the surface layer were determined by the following method. Analysis of O, N, C, H, and Ti was performed using GDS. For the measurement, JOBIN YVON GD-Profiler 2 manufactured by Horiba, Ltd. was used. The measurement conditions were a constant power mode of 35 W, an argon gas pressure of 600 Pa, and a discharge range of 4 mm in diameter. In the measurement by GDS, the measurement pitch was 0.5 nm.
The concentration (atomic %) of each of the above elements was calculated with the total of the above elements being 100 atomic %. The range from the surface of the titanium material to the position where the oxygen concentration measured in the thickness direction by GDS was 1/3 of the maximum value was defined as the surface layer portion of the titanium material. The average nitrogen concentration, average carbon concentration, and average hydrogen concentration were the arithmetic average values of the nitrogen concentration, carbon concentration, and hydrogen concentration values at each measurement point.
　チタン材の表面におけるα相のＴｉのｃ軸の格子定数は、平行ビーム法を用いたＸ線回折測定によって求められた。平行ビーム法を用いたＸ線回折測定には、株式会社リガク製Ｘ線回折装置　ＳｍａｒｔＬａｂが使用され、Ｘ線源はＣｏ－Ｋα（波長　λ＝１．７９０２Å）であった。Ｋβ線の除去にはＸ線の入射側にＷ／Ｓｉ多層膜ミラーを使用した。Ｘ線源負荷電力（管電圧／管電流）は、それぞれ、５．４ｋＷ（４０ｋＶ／１３５ｍＡ）であった。Ｘ線の試料への入射角は０．３度であり、回折角２θが走査された。測定試料には、板厚０．４ｍｍのチタン材を機械加工によって、２５ｍｍ（縦）×５０ｍｍ（横）の寸法に切り出し、チタン材表面の中央位置、言い換えると測定試料の表面の１２.５ｍｍ（縦）×２５ｍｍ（横）の位置を中心として、ビームを照射して、測定を実施した。なお、切り出された試料は、測定する表面に汚れが付着している可能性があるため、アセトンを用いて洗浄した。 The c-axis lattice constant of α-phase Ti on the surface of the titanium material was determined by X-ray diffraction measurement using the parallel beam method. For the X-ray diffraction measurement using the parallel beam method, an X-ray diffractometer SmartLab manufactured by Rigaku Co., Ltd. was used, and the X-ray source was Co-Kα (wavelength λ = 1.7902 Å). To remove Kβ rays, a W/Si multilayer mirror was used on the X-ray incident side. The X-ray source load power (tube voltage/tube current) was 5.4 kW (40 kV/135 mA), respectively. The incident angle of the X-rays on the sample was 0.3 degrees, and the diffraction angle 2θ was scanned. For the measurement sample, a titanium material with a thickness of 0.4 mm was machined and cut into a size of 25 mm (vertical) x 50 mm (horizontal). Measurements were performed by irradiating a beam centered on a position of 25 mm (vertical) x 25 mm (horizontal). Note that the cut sample was cleaned using acetone because there was a possibility that dirt was attached to the surface to be measured.
　チタン材の板厚中央におけるα相のＴｉのｃ軸の格子定数は、集中法を用いたＸ線回折によって測定された。チタン材の板厚中央におけるα相のＴｉの結晶構造の解析に使用される試料は、チタン材の板厚中央がＸ線回折測定を行う測定面となるように、機械研磨および電解研磨によって仕上げた。集中法を用いたＸ線回折測定には、平行ビーム法を用いたＸ線回折測定に使用されたＸ線回折装置を使用し、Ｘ線源、Ｋβ線の除去フィルター、およびＸ線源負荷電力も上記平行ビーム法の条件と同一とした。 The c-axis lattice constant of α-phase Ti at the center of the thickness of the titanium material was measured by X-ray diffraction using the concentration method. The sample used to analyze the crystal structure of α-phase Ti at the center of the thickness of the titanium material is finished by mechanical polishing and electrolytic polishing so that the center of the thickness of the titanium material becomes the measurement surface for X-ray diffraction measurements. Ta. For X-ray diffraction measurements using the focused method, the X-ray diffraction device used for X-ray diffraction measurements using the parallel beam method is used, and the X-ray source, Kβ ray removal filter, and X-ray source load power are The conditions were also the same as those for the parallel beam method above.
　チタン材の表面および板厚中央におけるα相のＴｉのｃ軸の格子定数は、（０００２）面の回折ピークから算出された。
　チタン材の表面におけるα相のＴｉのｃ軸の格子定数の差は、チタン材表面で算出された格子定数と板厚中央において算出された格子定数との差から求めた。 The c-axis lattice constant of α-phase Ti on the surface of the titanium material and at the center of the plate thickness was calculated from the diffraction peak of the (0002) plane.
The difference in the c-axis lattice constant of α-phase Ti on the surface of the titanium material was determined from the difference between the lattice constant calculated on the surface of the titanium material and the lattice constant calculated at the center of the plate thickness.
　酸化皮膜の厚さは、ＧＤＳによって上記方法で測定された酸素濃度によって求められた。具体的には、表面から、酸素濃度が最大値に対して半減した位置までの厚さ方向の距離を酸化皮膜の厚さとした。 The thickness of the oxide film was determined by the oxygen concentration measured using the above method using GDS. Specifically, the distance in the thickness direction from the surface to the position where the oxygen concentration was half of the maximum value was defined as the thickness of the oxide film.
　酸化皮膜に含有される窒化物由来の窒素の含有量は、次の方法で測定した。すなわち、以下の方法で測定した深さ方向の窒化物由来の窒素濃度の分布より、酸化皮膜内の最大値を酸化皮膜に含有される窒化物由来の窒素の含有量とした。 The content of nitrogen derived from nitrides contained in the oxide film was measured by the following method. That is, from the distribution of nitride-derived nitrogen concentration in the depth direction measured by the following method, the maximum value in the oxide film was taken as the content of nitride-derived nitrogen contained in the oxide film.
　酸化皮膜内の窒化物由来の窒素濃度および炭化物由来の炭素濃度の深さ方向（膜厚方向）の分布、ならびにチタン基材における酸化皮膜との界面近傍（当該界面からチタン基材側に２０ｎｍ）の窒化物由来の窒素濃度は、以下の方法で測定した。すなわち、ＸＰＳを用い、チタン材の表面をＡｒイオンスパッタリングして深さ方向の濃度分布を測定し、Ｎ１ｓ、Ｃ１ｓ、Ｏ１ｓおよびＴｉ２ｐの各ピーク位置それぞれの元素の状態を分析し、窒化物、炭化物、酸化物に由来するＮ、Ｃ、ＯおよびＴｉの濃度を算出した。詳細は上述した手順で算出した。ＸＰＳの分析条件は、以下のとおりとした。
　　装置：アルバック・ファイ製　Ｑｕａｎｔｅｒａ　ＳＸＭ
　　Ｘ線源：ｍｏｎｏ－ＡｌＫα（ｈν:１４８６．６ｅＶ）
　　ビーム径：２００μｍΦ（≒分析領域）
　　検出深さ：数ｎｍ
　　取込角度：４５°
　　スパッタ条件：Ａｒ＋、スパッタレート４．３ｎｍ/ｍｉｎ.（ＳｉＯ２換算値）
　ＳｉＯ２換算値とは、あらかじめエリプソメーターを用いて厚さを測定したＳｉＯ２膜を用いて、同一測定条件で求めたときのスパッタリング速度である。 Distribution of the nitrogen concentration derived from nitrides and the carbon concentration derived from carbides in the oxide film in the depth direction (film thickness direction), and near the interface with the oxide film on the titanium base material (20 nm from the interface to the titanium base material side) The concentration of nitrogen derived from nitrides was measured by the following method. That is, using XPS, the surface of the titanium material was sputtered with Ar ions to measure the concentration distribution in the depth direction, and the state of each element at each peak position of N1s, C1s, O1s and Ti2p was analyzed, and nitrides, carbides, etc. , the concentrations of N, C, O, and Ti derived from oxides were calculated. The details were calculated using the procedure described above. The analysis conditions for XPS were as follows.
Equipment: Quantera SXM manufactured by ULVAC-PHI
X-ray source: mono-AlKα (hν:1486.6eV)
Beam diameter: 200μmΦ (≒ analysis area)
Detection depth: several nm
Intake angle: 45°
Sputtering conditions: Ar + , sputtering rate 4.3 nm/min. (SiO 2 equivalent value)
The SiO 2 equivalent value is a sputtering rate determined under the same measurement conditions using an SiO 2 film whose thickness was measured in advance using an ellipsometer.
　製造したチタン材の表面粗さの各パラメータ（算術平均粗さＲａ、輪郭曲線要素の平均長さＲＳｍ、粗さ曲線要素の二乗平均平方根傾斜ＲΔｑ、クルトシスＲｋｕ、スキューネスＲｓｋ）を、ＪＩＳ　Ｂ　０６０１：２０１３に準拠し、以下の条件で測定した。
　　装置機器：表面粗さ形状測定機（（株）東京精密製　ＳＵＲＦＣＯＭ　１９００ＤＸ、解析ソフトウェア：ＴｉＭＳ　Ｖｅｒ．９．０．３）
　　測定子：（株）東京精密製形状測定子（型式：ＤＴ４３８０１）
　　パラメータ算出規格：ＪＩＳ－０１規格
　　測定種別：粗さ測定
　　カットオフ種別：ガウシアン
　　傾斜補正：最小二乗直線補正
　　測定距離：５．０ｍｍ
　　カットオフ波長λｃ：０．８ｍｍ
　　測定レンジ：±６４．０μｍ
　　測定速度：０．３ｍｍ／ｓｅｃ
　　移動・戻り速度：０．６ｍｍ／ｓｅｃ
　　リターン設定：通常測定
　　予備駆動長さ：（カットオフ波長／３）×２
　　測定間隔Δｘ：０．１９５μｍ
　　λsカットオフ比：３００
　　λsカットオフ波長：２．６６７μｍ
　　ピックアップ種別：標準ピックアップ
　　極性：正転 Each parameter of the surface roughness of the manufactured titanium material (arithmetic mean roughness Ra, average length RSm of contour curve element, root mean square slope RΔq of roughness curve element, kurtosis Rku, skewness Rsk) was determined according to JIS B 0601: 2013, and was measured under the following conditions.
Equipment: Surface roughness profile measuring machine (SURFCOM 1900DX manufactured by Tokyo Seimitsu Co., Ltd., analysis software: TiMS Ver. 9.0.3)
Measuring head: Shape measuring head manufactured by Tokyo Seimitsu Co., Ltd. (Model: DT43801)
Parameter calculation standard: JIS-01 standard Measurement type: Roughness measurement Cutoff type: Gaussian Inclination correction: Least square linear correction Measurement distance: 5.0mm
Cutoff wavelength λc: 0.8mm
Measurement range: ±64.0μm
Measurement speed: 0.3mm/sec
Movement/return speed: 0.6mm/sec
Return setting: Normal measurement Preliminary drive length: (cutoff wavelength/3) x 2
Measurement interval Δx: 0.195μm
λs cutoff ratio: 300
λs cutoff wavelength: 2.667μm
Pickup type: Standard pickup Polarity: Forward rotation
　測定位置は、Ｒａが最大となる方向で３点測定してその平均値を求めた。ここで、Ｒａが最大となる方向は、チタン材が板の場合には圧延方向と平行な方向を０°として、２２．５°、４５°、９０°（圧延方向に垂直な方向）の４方向にて粗さを測定し、Ｒａが最大となる方向を決定した。圧延ロールを用いてチタン素材を圧延してチタン材を場合や、砥粒が埋め込まれたロールを圧延方向に回転させて板表面を研磨した場合には、圧延方向に垂直な方向である９０°方向にて、Ｒａが最大となった。 Measurements were taken at three points in the direction where Ra was maximum, and the average value was calculated. Here, when the titanium material is a plate, the direction parallel to the rolling direction is 0°, and the directions in which Ra is maximum are 22.5°, 45°, and 90° (direction perpendicular to the rolling direction). The roughness was measured in the direction, and the direction in which Ra was maximum was determined. When a titanium material is rolled using a rolling roll, or when a roll with embedded abrasive grains is rotated in the rolling direction to polish the plate surface, the angle is 90° perpendicular to the rolling direction. In this direction, Ra became maximum.
　製造されたチタン材のそれぞれを、ｐＨ３、６０℃の硫酸水溶液中に４週間浸漬し、浸漬前後の色差を算出し、色差の値に基づいて、耐変色性の評価を実施した。色差ΔＥが、０以上５以下の場合を耐変色性が極めて良好（Ａ）であるとし、５超１０以下の場合を耐変色性が良好（Ｂ）であるとし、１０超の場合を不良（Ｃ）と判断した。なお、試験前後の色差ΔＥは
　ΔＥ＝（（Ｌ＊２－Ｌ＊１）２＋（ａ＊２－ａ＊１）２＋（ｂ＊２－ｂ＊１）２）１／２によって算出した。
　ここで、Ｌ＊１、ａ＊１、ｂ＊１は変色試験前の色彩の測定結果であり、Ｌ＊２、ａ＊２、ｂ＊２は、変色試験後の色彩の測定結果であり、ＪＩＳ　Ｚ　８７２９に規定されているＬ＊ａ＊ｂ＊表色法に基づくものである。
　また、色差の測定は、株式会社コニカミノルタ社製ＣＲ４００を用いて測定面積の直径８ｍｍでＤ６５の光源を用いた条件で実施した。 Each of the manufactured titanium materials was immersed in an aqueous sulfuric acid solution at pH 3 and 60° C. for 4 weeks, the color difference before and after immersion was calculated, and the color fastness was evaluated based on the color difference value. When the color difference ΔE is 0 or more and 5 or less, the color fastness is extremely good (A), when it is more than 5 and 10 or less, the color fastness is good (B), and when it is more than 10, it is considered poor ( It was determined that C). The color difference ΔE before and after the test was calculated by ΔE = ((L*2-L*1) 2 + (a*2-a*1) 2 + (b*2-b*1) 2 ) 1/2. .
Here, L*1, a*1, b*1 are the color measurement results before the color change test, and L*2, a*2, b*2 are the color measurement results after the color change test, It is based on the L*a*b* color system specified in JIS Z 8729.
Moreover, the color difference measurement was carried out using CR400 manufactured by Konica Minolta Co., Ltd. under the conditions of a measurement area with a diameter of 8 mm and a D65 light source.
　また、製造された各チタン材に対し、目視による官能評価を行った。目視観察による評価は、本変色促進試験に供していないチタン材と本変色促進試験後のチタン材を平板上に並べておき、１０名の評価人が太陽光下で様々な角度から見比べて、変色が目立って視認される角度があったか否かを判断した。変色が目立たないと１０名の評価人の９０％以上が判定した場合をＡ＋＋＋とし、変色が目立たないと１０名の評価人の８０％以上９０％未満が判定した場合をＡ＋＋とし、変色が目立たないと１０名の評価人の７０％以上８０％未満が判定した場合をＡ＋とし、変色が目立たないと１０名の評価人の５０％以上７０％未満が判定した場合をＡ０とし、変色が目立たないと１０名の評価人の３０％以上５０％未満が判定した場合をＢとし、変色が目立たないと１０名の評価人の３０％未満が判定した場合をＣとし、評価がＣである場合を不合格とした。なお、この目視観察は、実際の建築物の屋根や壁を想定した条件であり、見る角度によって色調が変わることも想定しての評価である。
　結果を表２、３に示す。表２、３中の下線は、本発明の範囲外であることを示す。 In addition, visual sensory evaluation was performed on each of the manufactured titanium materials. Evaluation by visual observation is performed by arranging titanium materials that have not been subjected to this accelerated discoloration test and titanium materials that have undergone this accelerated discoloration test on a flat plate, and having 10 evaluators compare the results by looking at them from various angles under sunlight. It was determined whether there was an angle at which it was conspicuously visible. If 90% or more of the 10 evaluators judged that the discoloration was not noticeable, it was rated A+++, and if 80% or more but less than 90% of the 10 evaluators judged that the discoloration was not noticeable, it was rated A++, and the discoloration was not noticeable. If 70% or more and less than 80% of the 10 evaluators judged that the discoloration was not noticeable, it was rated A+, and if 50% or more and less than 70% of the 10 evaluators judged that the discoloration was not noticeable, it was rated A0, and the discoloration was not noticeable. If 30% or more of the 10 evaluators but less than 50% of the 10 evaluators judged that the discoloration was not noticeable, it would be rated B. If less than 30% of the 10 evaluators judged that the discoloration was not noticeable, it would be rated C. If the evaluation is C. was rejected. Note that this visual observation is performed under conditions that assume the roof and walls of an actual building, and the evaluation assumes that the color tone changes depending on the viewing angle.
The results are shown in Tables 2 and 3. The underline in Tables 2 and 3 indicates that it is outside the scope of the present invention.
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
　本発明例１～２３は、表層部の平均窒素濃度および平均炭素濃度のいずれも１４．０原子％以下であり、平均水素濃度が３０．０原子％以下であり、チタン材の表面および板厚中央のα相のＴｉのｃ軸の格子定数の差は０．０１５Å以下であり、これらの色差評価結果はＢ以上であり、目視による官能評価結果はＢ以上であった。
　比較例１は、焼鈍処理時の真空度が１．０×１０－１Ｐａと低かったため、表層部の平均窒素濃度が高かった。その結果、比較例１のチタン材の色差評価結果および目視による官能評価結果はいずれも不合格であった。
　比較例２は、焼鈍温度が低く、表層部の平均炭素濃度が高かった。その結果、比較例２のチタン材の色差評価結果および目視による官能評価結果はいずれも不合格であった。
　比較例３は、焼鈍処理時の真空度が８．０×１０－２Ｐａと低かったため、チタン材の表層部の酸素濃度が高くなり、表層部におけるα相のＴｉのｃ軸の格子定数が大きくなり、格子定数の差が大きくなったと推察される。その結果、比較例３のチタン材の色差評価結果および目視による官能評価結果はいずれも不合格であった。
　比較例４、５では、表層部の平均水素濃度が高く、比較例３のチタン材の色差評価結果および目視による官能評価結果はいずれも不合格であった。 In Inventive Examples 1 to 23, the average nitrogen concentration and average carbon concentration in the surface layer portion are both 14.0 at% or less, the average hydrogen concentration is 30.0 at% or less, and the surface and plate thickness of the titanium material are The difference in the c-axis lattice constant of Ti in the central α phase was 0.015 Å or less, the color difference evaluation results were B or higher, and the visual sensory evaluation results were B or higher.
In Comparative Example 1, the degree of vacuum during the annealing treatment was as low as 1.0×10 −1 Pa, so the average nitrogen concentration in the surface layer portion was high. As a result, both the color difference evaluation result and the visual sensory evaluation result of the titanium material of Comparative Example 1 failed.
Comparative Example 2 had a low annealing temperature and a high average carbon concentration in the surface layer. As a result, both the color difference evaluation result and the visual sensory evaluation result of the titanium material of Comparative Example 2 failed.
In Comparative Example 3, the degree of vacuum during the annealing treatment was as low as 8.0 × 10 -2 Pa, so the oxygen concentration in the surface layer of the titanium material increased, and the c-axis lattice constant of α-phase Ti in the surface layer decreased. It is presumed that the difference in lattice constants has become larger. As a result, both the color difference evaluation result and the visual sensory evaluation result of the titanium material of Comparative Example 3 failed.
In Comparative Examples 4 and 5, the average hydrogen concentration in the surface layer portion was high, and both the color difference evaluation result and the visual sensory evaluation result of the titanium material of Comparative Example 3 failed.
　以上示したように、本実施形態に係るチタン材は、厳しい酸性雨を模擬したｐＨ３の硫酸水溶液中においても長期間、優れた耐変色性を有していた。本発明は、屋根あるいは壁パネルのような屋外環境での用途に特に有効であり、その産業上の価値は極めて高いといえる。 As shown above, the titanium material according to the present embodiment had excellent discoloration resistance for a long period of time even in a pH 3 sulfuric acid aqueous solution simulating severe acid rain. The present invention is particularly effective for applications in outdoor environments such as roof or wall panels, and its industrial value can be said to be extremely high.
（実施例２）
　表４に示したチタン素材を０．４ｍｍの厚さに冷間圧延した後、アルカリまたは有機溶媒等を用いて脱脂し、チタン素材の表面の油分を除去した。その後、各チタン素材に対し、表４に示す条件で焼鈍処理を行った。表４に示す開放温度は、各焼鈍温度で各焼鈍時間の保持が行われた後、冷却過程において炉内を開放したときの温度である。このときの温度は、熱電対を用いて測定した炉内の温度である。 (Example 2)
The titanium materials shown in Table 4 were cold rolled to a thickness of 0.4 mm, and then degreased using an alkali or organic solvent to remove oil on the surface of the titanium materials. Thereafter, each titanium material was annealed under the conditions shown in Table 4. The opening temperature shown in Table 4 is the temperature when the inside of the furnace is opened in the cooling process after holding each annealing time at each annealing temperature. The temperature at this time is the temperature inside the furnace measured using a thermocouple.
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000011
　製造された各チタン材に対して、実施例１と同様の評価を行った。表５、６に結果を示す。 The same evaluation as in Example 1 was performed on each manufactured titanium material. The results are shown in Tables 5 and 6.
Figure JPOXMLDOC01-appb-T000012
Figure JPOXMLDOC01-appb-T000012
Figure JPOXMLDOC01-appb-T000013
Figure JPOXMLDOC01-appb-T000013
　表５、６に示すように本発明例２４～３９は、酸化皮膜におけるＸ線光電子分光法で分析したときの窒化物由来の窒素濃度の最大値が２．０～１０．０原子％であり、酸化皮膜における窒化物由来の窒素濃度が最大値を示す位置が、ＳｉＯ２のスパッタリング速度で換算したときに、前記酸化皮膜の表面から２～１０ｎｍの範囲に存在し、チタン基材における酸化皮膜との界面近傍に存在する窒化物由来の窒素の濃度が、酸化皮膜における窒化物由来の窒素濃度の最大値未満且つ７原子％以下であり、酸化皮膜における窒化物由来の窒素濃度の最大値が、酸化皮膜における窒化物由来の窒素濃度が最大となる位置の炭化物由来の炭素濃度以上であった。これらの色差評価結果はＡであり、更に目視による官能評価結果はいずれもＡ＋＋であり、耐変色性が優れていた。 As shown in Tables 5 and 6, in Examples 24 to 39 of the present invention, the maximum concentration of nitrogen derived from nitrides when analyzed by X-ray photoelectron spectroscopy in the oxide film was 2.0 to 10.0 at%. , the position where the nitrogen concentration derived from nitride in the oxide film shows the maximum value exists in a range of 2 to 10 nm from the surface of the oxide film when converted to the sputtering rate of SiO 2 , and the oxide film on the titanium base material The concentration of nitrogen derived from nitrides existing near the interface with The concentration of nitrogen derived from nitride in the oxide film was higher than the carbon concentration derived from carbide at the maximum position. The color difference evaluation results were A, and the visual sensory evaluation results were all A++, indicating excellent color fastness.
（実施例３）
　表７に示したチタン素材を０．４ｍｍの厚さに冷間圧延した後、表７および表８に示す条件で、研磨工程、洗浄、焼鈍処理、およびダル圧延工程をこの順序で行った。表７に示した「研磨パス数」とは、研磨ベルトを配置した３台の研磨スタンドからなるコイルグラインダのラインへのチタン素材の通板回数を示している。
　本発明例４０～７２では、各チタン素材に対し、表８に示す条件で最終焼鈍処理を行った。表８に示す開放温度は、各焼鈍温度で各焼鈍時間の保持が行われた後、冷却過程において炉内を開放したときの温度である。このときの温度は、熱電対を用いて測定した炉内の温度である。
　本発明例４０～６１、６３～７２では、表８の「真空度」に示す真空雰囲気下で加熱が開始され、冷却の開始までの間に、焼鈍炉内に９９．９９体積％以上のＡｒガスが導入された。各チタン素材が各焼鈍温度の炉内で各焼鈍時間だけ保持された後の冷却過程では、表８に示す開放温度まで各焼鈍雰囲気が維持され、開放温度まで炉内の温度が低下した時点で炉内が開放された。
　本発明例６２では、表８の「真空度」に示す真空雰囲気下で加熱が開始され、炉内が開放されるまで当該真空度が維持された。
　比較例６では、チタン素材を０．４ｍｍの厚さに冷間圧延した後、アルカリまたは有機溶媒等を用いて脱脂した後、最終焼鈍処理を実施せずに、硝フッ酸酸洗仕上げが行われた。 (Example 3)
After cold rolling the titanium materials shown in Table 7 to a thickness of 0.4 mm, a polishing step, cleaning, annealing treatment, and dull rolling step were performed in this order under the conditions shown in Tables 7 and 8. The "number of polishing passes" shown in Table 7 indicates the number of times the titanium material was passed through the line of a coil grinder consisting of three polishing stands on which polishing belts were arranged.
In Examples 40 to 72 of the present invention, each titanium material was subjected to final annealing treatment under the conditions shown in Table 8. The opening temperatures shown in Table 8 are the temperatures when the inside of the furnace was opened in the cooling process after each annealing time was maintained at each annealing temperature. The temperature at this time is the temperature inside the furnace measured using a thermocouple.
In Examples 40 to 61 and 63 to 72 of the present invention, heating was started under the vacuum atmosphere shown in "Degree of Vacuum" in Table 8, and until the start of cooling, 99.99% by volume or more of Ar was present in the annealing furnace. gas was introduced. In the cooling process after each titanium material is held in the furnace at each annealing temperature for each annealing time, each annealing atmosphere is maintained up to the opening temperature shown in Table 8, and when the temperature in the furnace has decreased to the opening temperature. The inside of the furnace was opened.
In Inventive Example 62, heating was started under the vacuum atmosphere shown in "Degree of Vacuum" in Table 8, and the vacuum degree was maintained until the inside of the furnace was opened.
In Comparative Example 6, a titanium material was cold rolled to a thickness of 0.4 mm, degreased using an alkali or organic solvent, and then finished by pickling with nitric hydrofluoric acid without performing a final annealing treatment. I was disappointed.
Figure JPOXMLDOC01-appb-T000014
Figure JPOXMLDOC01-appb-T000014
Figure JPOXMLDOC01-appb-T000015
Figure JPOXMLDOC01-appb-T000015
　製造された各チタン材に対して、実施例１と同様の評価を行った。表９、１０に結果を示す。表９中の下線は、本発明の範囲外であることを示す。 The same evaluation as in Example 1 was performed on each manufactured titanium material. The results are shown in Tables 9 and 10. The underline in Table 9 indicates that it is outside the scope of the present invention.
Figure JPOXMLDOC01-appb-T000016
Figure JPOXMLDOC01-appb-T000016
Figure JPOXMLDOC01-appb-T000017
Figure JPOXMLDOC01-appb-T000017
　表７～１０に示すように、熱処理温度、時間および熱処理雰囲気、ならびに冷却雰囲気を制御すれば、算術平均粗さＲａが最大となる方向の粗さ曲線において、算術平均粗さＲａと要素長さＲＳｍの比であるＲａ／ＲＳｍが０．００６～０．０１５であり、かつ、二乗平均平方根傾斜ＲΔｑが０．１５０～０．２８０であり、チタン基材のクルトシスＲｋｕが３超であり、チタン基材のスキューネスＲｓｋが－０．５超にすることができ、評価結果がより一層優れることが分かった。特に、本発明例５９～６１は、表層部の平均窒素濃度および平均炭素濃度のいずれも１４．０原子％以下であり、平均水素濃度が３０．０原子％以下であり、チタン材の表面および板厚中央のα相のＴｉのｃ軸の格子定数の差は０．０１５Å以下であり、酸化皮膜におけるＸ線光電子分光法で分析したときの窒化物由来の窒素濃度の最大値が２．０～１０．０原子％であり、酸化皮膜における窒化物由来の窒素濃度が最大値を示す位置が、ＳｉＯ２のスパッタリング速度で換算したときに、前記酸化皮膜の表面から２～１０ｎｍの範囲に存在し、チタン基材における酸化皮膜との界面近傍に存在する窒化物由来の窒素の濃度が、酸化皮膜における窒化物由来の窒素濃度の最大値未満且つ７原子％以下であり、酸化皮膜における窒化物由来の窒素濃度の最大値が、酸化皮膜における窒化物由来の窒素濃度が最大となる位置の炭化物由来の炭素濃度以上であった。その結果、これらの色差評価結果はＡであり、目視による官能評価結果はＡ＋＋＋であり、耐変色性が極めて優れるものであった。 As shown in Tables 7 to 10, if the heat treatment temperature, time, heat treatment atmosphere, and cooling atmosphere are controlled, the arithmetic mean roughness Ra and element length will change in the roughness curve in the direction where the arithmetic mean roughness Ra is maximum. The ratio of RSm, Ra/RSm, is 0.006 to 0.015, the root mean square slope RΔq is 0.150 to 0.280, the kurtosis Rku of the titanium base material is more than 3, and the titanium base material has a kurtosis Rku of more than 3. It was found that the skewness Rsk of the base material could be made to exceed -0.5, and the evaluation results were even more excellent. In particular, in Examples 59 to 61 of the present invention, both the average nitrogen concentration and the average carbon concentration in the surface layer portion are 14.0 atomic % or less, the average hydrogen concentration is 30.0 atomic % or less, and the surface layer of the titanium material and The difference in the c-axis lattice constant of Ti in the α phase at the center of the plate thickness is less than 0.015 Å, and the maximum concentration of nitrogen derived from nitrides when analyzed by X-ray photoelectron spectroscopy in the oxide film is 2.0. ~10.0 at%, and the position where the nitrogen concentration derived from nitride in the oxide film shows the maximum value exists within a range of 2 to 10 nm from the surface of the oxide film when converted to the sputtering rate of SiO 2 However, the concentration of nitride-derived nitrogen present near the interface with the oxide film in the titanium base material is less than the maximum value of the nitride-derived nitrogen concentration in the oxide film and 7 at% or less, and the nitride in the oxide film The maximum value of the nitrogen concentration derived from the carbide was higher than the carbon concentration derived from the carbide at the position where the nitrogen concentration derived from the nitride in the oxide film was the maximum. As a result, the color difference evaluation result was A, and the visual sensory evaluation result was A+++, indicating that the color fastness was extremely excellent.
　１　　　チタン材
　１０　　　チタン基材
　２０　　　酸化皮膜
　３０　　　表層部 1 Titanium material 10 Titanium base material 20 Oxide film 30 Surface layer part

Claims (5)

  1. 　表面から、グロー放電分光分析法によって前記表面から厚さ方向に測定された酸素濃度が最大値の１／３である位置までの範囲の平均窒素濃度および平均炭素濃度がそれぞれ１４．０原子％以下、平均水素濃度が３０．０原子％以下であり、
    　前記表面において入射角が０．３度である平行ビーム法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数と、板厚中央において集中法によるＸ線回折測定によって求められるα相のＴｉのｃ軸の格子定数との差が０．０１５Å以下である、
    　チタン材。     The average nitrogen concentration and average carbon concentration in the range from the surface to the position where the oxygen concentration measured in the thickness direction from the surface by glow discharge spectrometry is 1/3 of the maximum value are each 14.0 at % or less , the average hydrogen concentration is 30.0 at% or less,
    The c-axis lattice constant of α-phase Ti determined by X-ray diffraction measurement using the parallel beam method with an incident angle of 0.3 degrees on the surface, and α determined by X-ray diffraction measurement using the concentrated method at the center of the plate thickness. The difference from the c-axis lattice constant of Ti in the phase is 0.015 Å or less,
    Titanium material.
  2. 　厚さが３０．０ｎｍ以下の酸化皮膜を備える、
    　請求項１に記載のチタン材。     comprising an oxide film with a thickness of 30.0 nm or less,
    The titanium material according to claim 1.
  3. 　チタン基材と、
    　前記チタン基材の表面に配された酸化皮膜と、を有し、
    　Ｘ線光電子分光法で分析したとき、
    　前記酸化皮膜における窒化物由来の窒素濃度の最大値が２．０～１０．０原子％であり、
    　前記酸化皮膜における前記窒化物由来の窒素濃度が最大値を示す位置が、ＳｉＯ２のスパッタリング速度で換算したときに、前記酸化皮膜の表面から２～１０ｎｍの範囲に存在し、
    　酸素濃度が最大値の１／２になる位置からチタン基材側まで２０ｎｍ範囲に存在する前記窒化物由来の窒素の濃度が、前記酸化皮膜における前記窒化物由来の窒素濃度の最大値未満且つ７原子％以下であり、
    　前記酸化皮膜における前記窒化物由来の前記窒素濃度の最大値が、前記酸化皮膜における前記窒化物由来の前記窒素濃度が最大となる位置の炭化物由来の炭素濃度以上である、
    　請求項１または２に記載のチタン材。     titanium base material,
    an oxide film disposed on the surface of the titanium base material,
    When analyzed by X-ray photoelectron spectroscopy,
    The maximum value of nitrogen concentration derived from nitride in the oxide film is 2.0 to 10.0 at%,
    A position where the nitrogen concentration derived from the nitride in the oxide film has a maximum value exists in a range of 2 to 10 nm from the surface of the oxide film when converted to a sputtering rate of SiO 2 ,
    The concentration of nitrogen derived from the nitride present in a range of 20 nm from the position where the oxygen concentration is 1/2 of the maximum value to the titanium base material side is less than the maximum value of the nitrogen concentration derived from the nitride in the oxide film, and less than atomic%,
    The maximum value of the nitrogen concentration derived from the nitride in the oxide film is greater than or equal to the carbide-derived carbon concentration at the position where the nitrogen concentration derived from the nitride in the oxide film is maximum.
    The titanium material according to claim 1 or 2.
  4. 　算術平均粗さＲａが最大となる方向の粗さ曲線において、算術平均粗さＲａと要素長さＲＳｍの比であるＲａ／ＲＳｍが０．００６～０．０１５であり、かつ、二乗平均平方根傾斜ＲΔｑが０．１５０～０．２８０であるチタン基材を備え、
    　前記チタン基材のクルトシスＲｋｕが３超であり、
    　前記チタン基材のスキューネスＲｓｋが－０．５超である、
    請求項１または２に記載のチタン材。     In the roughness curve in the direction where the arithmetic mean roughness Ra is maximum, Ra/RSm, which is the ratio of the arithmetic mean roughness Ra to the element length RSm, is 0.006 to 0.015, and the root mean square slope is A titanium base material having an RΔq of 0.150 to 0.280,
    The titanium base material has a kurtosis Rku of more than 3,
    The skewness Rsk of the titanium base material is greater than −0.5.
    The titanium material according to claim 1 or 2.
  5. 　前記チタン基材は、算術平均粗さＲａが最大となる方向の粗さ曲線において、算術平均粗さＲａと要素長さＲＳｍの比であるＲａ／ＲＳｍが０．００６～０．０１５であり、かつ、二乗平均平方根傾斜ＲΔｑが０．１５０～０．２８０であり、
    前記チタン基材のクルトシスＲｋｕが３超であり、
    前記チタン基材のスキューネスＲｓｋが－０．５超である、
    請求項３に記載のチタン材。     In the titanium base material, in the roughness curve in the direction where the arithmetic mean roughness Ra is maximum, Ra/RSm, which is the ratio of the arithmetic mean roughness Ra to the element length RSm, is 0.006 to 0.015, and the root mean square slope RΔq is 0.150 to 0.280,
    The titanium base material has a kurtosis Rku of more than 3,
    The skewness Rsk of the titanium base material is greater than −0.5.
    The titanium material according to claim 3.
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