WO2019176700A1 - Titanium powder and method for producing same - Google Patents

Titanium powder and method for producing same Download PDF

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Publication number
WO2019176700A1
WO2019176700A1 PCT/JP2019/008968 JP2019008968W WO2019176700A1 WO 2019176700 A1 WO2019176700 A1 WO 2019176700A1 JP 2019008968 W JP2019008968 W JP 2019008968W WO 2019176700 A1 WO2019176700 A1 WO 2019176700A1
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Prior art keywords
titanium
powder
mgcl
less
raw material
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PCT/JP2019/008968
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French (fr)
Japanese (ja)
Inventor
茂久 竹中
謙治 平嶋
千博 滝
斉藤　和也
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トーホーテック株式会社
日立金属株式会社
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Application filed by トーホーテック株式会社, 日立金属株式会社 filed Critical トーホーテック株式会社
Priority to EP19767251.2A priority Critical patent/EP3766601A4/en
Priority to JP2020506443A priority patent/JP6976415B2/en
Priority to CN201980019823.XA priority patent/CN112055628A/en
Publication of WO2019176700A1 publication Critical patent/WO2019176700A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/045—Alloys based on refractory metals
    • C22C1/0458—Alloys based on titanium, zirconium or hafnium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/023—Hydrogen absorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • B22F2009/048—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by pulverising a quenched ribbon

Definitions

  • the present invention relates to a titanium-based powder, and in particular, to an entirely new titanium-based powder produced by a hydrodehydrogenation method (hereinafter referred to as HDH method) and a method for producing the same.
  • a hydrodehydrogenation method hereinafter referred to as HDH method
  • Patent Document 1 Prior art documents relating to the production of titanium-based powder include Patent Document 1 and Patent Document 2.
  • titanium powder and titanium alloy powder are referred to as titanium-based powder.
  • JP-A-5-247503 Japanese Patent Laid-Open No. 7-278601
  • the present invention aims to solve the above problems, that is, to provide a titanium-based powder with reduced pores in the titanium-based powder.
  • the pore structure and generation mechanism were analyzed in detail.
  • the number of pores significantly changed, and the generation of pores was (or had) gas in the titanium-based powder.
  • the pore area ratio of the titanium-based powder divided by the cross-sectional area of the titanium-based powder divided by the area of the cross-section of the titanium-based powder is 0.3% or less.
  • the titanium powder may be HDH powder.
  • a titanium-based powder is produced by a hydrodehydrogenation method including a hydrogenation step, a pulverization step, and a dehydrogenation step using a titanium-based material, which is contained in the titanium-based material.
  • concentration of total MgCl 2 which is not more than 1.0 mass%
  • the production method of the titanium-based powder, wherein the internal MgCl 2 concentration is not more than 0.1mass% is provided.
  • the maximum thickness of the titanium-based raw material may be 20 mm or less.
  • the titanium hydride-based powder may be pulverized to a D95 particle size of 300 ⁇ m or less.
  • the temperature of the titanium-based raw material may be hydrogenated over a period of 90 minutes or more within the range of 716 ° C. or more and 1050 ° C. or less.
  • the generation of pores in titanium powder is closely related to gas. Number of titanium-based powders with pores by preventing gas from being involved in the titanium-based powder, generating no gas inside the titanium-based powder, or quickly removing the generated gas from inside the titanium-based powder. Can be significantly reduced.
  • Titanium powder is currently made from titanium sponge, which is mostly manufactured by the crawl method. In some cases, scrap is used as a raw material from the viewpoint of economy and resource protection.
  • the crawl method is a method of obtaining titanium metal by reducing titanium tetrachloride (TiCl 4 ) obtained by chlorinating titanium ore with magnesium (Mg).
  • MgCl 2 surface MgCl 2
  • MgCl 2 internal MgCl 2
  • the method for producing titanium powder is roughly divided into an atomizing method and an HDH method.
  • atomization method after melting a titanium raw material, titanium powder liquefied in Ar gas is made into fine liquid particles, and at the same time, rapidly cooled and solidified to produce titanium powder.
  • MgCl 2 internal MgCl 2
  • the gasified MgCl 2 is confined within the liquefied titanium grains and in the titanium powder. It is a mechanism that generates pores.
  • the second is a mechanism in which pores are generated in the titanium powder when the liquefied titanium grains are solidified by involving Ar gas or vaporized MgCl 2 gas. For this reason, it was concluded that the HDH method is suitable for achieving the object of the present invention.
  • the HDH method is a method in which a titanium raw material is once hydrogenated to form brittle TiH 2 , and then pulverized and dehydrogenated to obtain titanium powder. That is, it is a method for producing titanium powder (HDH powder) by the steps of hydrogenation, pulverization, dehydrogenation, and pulverization.
  • the said crushing process is arbitrary, it is preferable to perform a crushing process in manufacture of titanium powder (HDH powder).
  • the titanium raw material is charged into a hydrogenation furnace capable of vacuum replacement, and hydrogenated in a hydrogen gas atmosphere at a temperature of 400 ° C. or higher, and the hydrogen gas atmosphere is replaced with an Ar gas atmosphere. By doing so, a block of titanium hydride is obtained.
  • the titanium raw material is hydrogen embrittled by a hydrogenation process.
  • the titanium hydride lump is mechanically pulverized into a titanium hydride powder having a mechanical fracture surface, that is, a pulverized surface.
  • the obtained titanium hydride powder is classified and / or sieved to remove fine powder of titanium hydride.
  • a pulverizer such as a ball mill or a vibration mill can be used.
  • a sieve classification device such as a circular vibration sieve or an airflow classifier may be used.
  • the titanium hydride powder is filled in a container and charged in a vacuum heating type dehydrogenation furnace, for example, 450 ° C. or higher in a vacuum of 10 ⁇ 3 Torr (0.13 Pa) or lower.
  • a vacuum heating type dehydrogenation furnace for example, 450 ° C. or higher in a vacuum of 10 ⁇ 3 Torr (0.13 Pa) or lower.
  • Ar gas is inserted as needed.
  • the pre-sintered portion of the dehydrogenated titanium block pre-sintered in the dehydrogenation step is unwound and returned to a titanium powder shape having a pulverized or crushed surface after pulverization.
  • the present inventor has studied and investigated in detail the conditions in each manufacturing process of the HDH method from the viewpoint of pores, and investigated how to prevent the generation of pores.
  • the HDH method if the titanium is not melted and liquefied in each manufacturing process, Ar gas in the atmosphere is not involved and does not cause pores. Since the heat treatment by the HDH method is two steps of hydrogenation and dehydrogenation, both may be performed at a melting point or lower.
  • stainless steel is generally used as a container for titanium material, when the iron and titanium contained in the stainless steel come into contact with each other, the temperature of both exceeds the eutectic temperature of iron and titanium. Titanium becomes liquid and does not meet the above purpose. Therefore, the present inventor has found that in order to prevent the generation of pores, it is necessary to control titanium below the eutectic temperature of iron and titanium to prevent liquefaction of titanium. That is, controlling the upper limit temperature is an important component of the present invention.
  • Patent Document 1 and Patent Document 2 there is only a description that “the temperature is raised to 650 ° C. in a vacuum atmosphere”, and there is no description about the temperature control of the titanium material after the subsequent introduction of hydrogen gas. Since the hydrogenation reaction for hydrogenating titanium is an exothermic reaction, hydrogen absorption is first performed at 650 ° C., for example, in a vacuum furnace, and then the temperature rises spontaneously. For this reason, the temperature rise is suppressed while constantly observing how to put the titanium material into the container, the amount of hydrogen and Ar charged, the charging time, and the temperature of each part so that any place including the local part is below the eutectic temperature. Therefore, it is necessary to perform fine control such as cooling.
  • the boiling point of MgCl 2 under normal pressure is 1412 ° C. At this temperature, MgCl 2 (internal MgCl 2 ) confined inside the titanium raw material is gasified. On the other hand, since the melting point of titanium is 1668 ° C., titanium exists in a solid state at 1412 ° C. The gasified internal MgCl 2 has a larger volume than the solid state, and this causes a very high pressure state to be formed inside the titanium. This high-pressure state due to the gasified internal MgCl 2 can cause cracks in the titanium hydride that has become brittle by hydrogenation, from which MgCl 2 can be discharged to the outside of the titanium hydride.
  • the container in which the titanium material is put is often stainless steel, and cannot be raised above the eutectic temperature of iron and titanium (1085 ° C.).
  • an unprecedented control method that obeys this limited temperature and removes MgCl 2 that causes pores has been found, and the present invention has been completed. That is, the temperature of the titanium raw material temperature of MgCl 2 melting point (714 ° C.) or higher for a minimum the MgCl 2 liquid phase, is expanded compared to the volume of MgCl 2 in the solid state.
  • the volume of the internal MgCl 2 is larger in the liquid state than in the solid state, and this causes a very high pressure state to be formed inside the titanium.
  • This high-pressure state due to internal MgCl 2 in the liquid phase causes cracks in titanium hydride that has become brittle by hydrogenation.
  • the liquid phase MgCl 2 exposed to the outside of the titanium due to cracks is gradually vaporized by evaporation.
  • the temperature in the furnace and the control of the heating time are determined in consideration of the thickness of the titanium raw material to be hydrogenated and the hydrogenation time.
  • the pressure inside the titanium is increased by evaporated MgCl 2 before the titanium becomes brittle, the titanium softens and deforms easily at a high temperature, resulting in the formation of spherical pores inside the titanium.
  • MgCl 2 present in the titanium raw material evaporates from the cracks of titanium, and also hydrogenation of titanium is performed. Can be realized.
  • the temperature of the titanium raw material can be set in the range from the melting point of MgCl 2 (714 ° C.) or higher to the eutectic temperature of iron and titanium (1085 ° C.). Reliable temperature control can be performed.
  • the raw material titanium is prevented from melting by controlling the temperature.
  • MgCl 2 adheres to the surface of the titanium raw material, MgCl 2 is vaporized during the HDH process, and therefore it is preferable to use a high vacuum to remove the surface MgCl 2 .
  • hydrogenation that embodies the above-described mechanism found in the present invention to prevent generation of pores and to remove MgCl 2 (internal MgCl 2 ) existing inside titanium. Let it be a process. If embrittlement by hydrogenation is performed for a sufficient time, MgCl 2 can be discharged, but it is not industrially suitable in terms of productivity and cost.
  • controlling the amount of MgCl 2 present inside the titanium raw material has a significant effect on productivity and cost, in addition to controlling the amount of MgCl 2 adhering to the surface of the titanium raw material.
  • the total MgCl 2 concentration of the titanium raw material needs to be suppressed to 1.0 mass% or less.
  • the total MgCl 2 concentration of the titanium raw material is preferably suppressed to 0.05 mass% or less, more preferably 0.001 mass% or less.
  • the MgCl 2 concentration (internal MgCl 2 concentration) present in the titanium raw material is 0.5 mass% or less
  • the temperature of the titanium raw material is increased from the melting point (714 ° C.) of MgCl 2 to the iron and titanium in the HDH method. It has been found that MgCl 2 that causes pores can be efficiently removed even if the time for maintaining in the range below the eutectic temperature (1085 ° C.) is 90 minutes.
  • the effect is more clearly shown by setting the MgCl 2 concentration (internal MgCl 2 concentration) present in the titanium raw material to 0.1 mass% or less.
  • the MgCl 2 concentration (internal MgCl 2 concentration) confined inside the titanium raw material is preferably 0.1 mass% or less, and more preferably 0.001 mass% or less.
  • the titanium raw material has a maximum thickness of 20 mm or less, more preferably 10 mm or less. This is because when the maximum thickness of the titanium raw material is 20 mm or less, hydrogen sufficiently spreads inside the raw material during hydrogenation, embrittles titanium and promptly causes cracks.
  • Chlorine concentration of the target titanium raw material is measured by silver nitrate titration method (JIS H 1615), converted to MgCl 2 concentration from the value of the chlorine concentration, and this is the MgCl 2 concentration (total MgCl 2 concentration) contained in the titanium raw material.
  • JIS H 1615 silver nitrate titration method
  • the hydrogenated titanium hydride is pulverized into fine titanium hydride powder with a pulverized surface. Can be further enhanced. The probability that the pores are released increases as the particle size of the titanium hydride powder is made finer.
  • the particle size of the titanium hydride powder may be 300 ⁇ m or less, preferably 150 ⁇ m or less.
  • the particle size of the titanium hydride powder produced and pulverized by the HDH method has a distribution, and 95% or more of the particle size of the total titanium hydride powder may be less than the above value.
  • the titanium hydride powder has a D95 particle size of 300 ⁇ m or less, preferably 150 ⁇ m or less.
  • the lower limit side of the D95 particle size is not particularly limited, for example, it may be 70 ⁇ m or more, or 80 ⁇ m or more.
  • D95 indicates a particle size at which the volume-based cumulative distribution is 95% in the particle size distribution measurement obtained by the laser diffraction / scattering method. In detail, it measures based on JISZ8825: 2013.
  • 95% or more of the total titanium particle diameter of the titanium powder produced and crushed by the HDH method may be 150 ⁇ m or less.
  • the titanium powder produced by the HDH method described above melts the surface of the titanium powder (for example, plasma melting), and spheroidizes the angular surface that is the pulverized or crushed surface to obtain a spherical powder. Therefore, it is suitable as a raw material powder. Since the titanium powder produced and crushed by the HDH method has a pulverized surface or a pulverized surface having a concavo-convex structure, melting when introduced into plasma can be promoted by its large surface area. In addition, even if the titanium powder surface is melted for spheroidization, plasma gas such as Ar is not involved, and new pores can be suppressed.
  • plasma gas such as Ar is not involved, and new pores can be suppressed.
  • the temperature, time, hydrogen blowing amount, material shape, and MgCl 2 carry-in amount are appropriately controlled as described above.
  • the present inventors have found that this can be achieved, and have completed the present invention.
  • the explanation is based on titanium powder.
  • the titanium alloy powder containing 50% by mass or less of elements such as Al and V in titanium, the titanium alloy as a raw material is prevented from melting by controlling the temperature by the HDH method, and the same effect as titanium powder is obtained.
  • the element contained in titanium is preferably 20% by mass or less, and more preferably 15% by mass or less.
  • the titanium alloy powder may contain a plurality of types of elements.
  • the titanium alloy powder may be Ti—Al—V alloy powder.
  • the Ti—Al—V alloy powder can have an Al content of 5.5 to 7.5 mass% and a V content of 3.5 to 4.5 mass%.
  • the cross-sectional area of an embedded pore (hereinafter referred to as an internal pore) that appeared after observing an arbitrary cross-section of the titanium-based powder was divided by the area of the cross-section of the titanium-based powder. It can be realized that the value (pore area ratio of the cross section) is 0.3% or less.
  • the titanium-based powder produced in the present invention preferably has an internal pore number of 20 / mm 2 or less per unit area that appears when an arbitrary cross section of the titanium-based powder is observed.
  • the pore area ratio of the titanium-based powder cross section is 0.3% or less.
  • the cross section is measured with an optical microscope at a magnification of 500 times and an arbitrary portion of 700 ⁇ m ⁇ 500 ⁇ m size. It means that the value obtained by dividing the cross-sectional area of the internal pores observed as an image in the range of luminance 90 to 250 by image processing when observed at 16 locations is 0.3% or less. .
  • the number of internal pores means the number of internal pores observed as an image having a luminance in the range of 90 to 250 by image processing when observed. In any observation, powder having a major axis of 10 ⁇ m or less is excluded by image processing. Also, in the image processing, pores that are clearly open from the original image even though they look like internal pores were excluded (FIG.
  • FIG. 1 is a photograph before image processing
  • FIG. 2 is a photograph after image processing.
  • the calculation is performed as one as long as it is one internal pore connected by image processing.
  • the pore area ratio of the cross section is 0.3% or less
  • the titanium powder produced by the production method according to the present invention is used in a technical field (for example, aircraft materials) where the pores must be small. It is suitable to do.
  • the pore area ratio of the cross section exceeds 0.3 percent, it is difficult to use in the technical field.
  • Sponge titanium was used as a titanium raw material.
  • the titanium raw materials used were those having a total MgCl 2 concentration and an internal MgCl 2 concentration of 0.05 mass% or less and a diameter of 1/2 inch or less.
  • the atmosphere was heated to 650 ° C. with a heater and held for 120 minutes. Thereafter, hydrogen was supplied to cause a reaction of hydrogen storage exotherm, and the heater was controlled, the Ar gas was inserted and the cooling device was operated, and hydrogenation was performed for 120 minutes while controlling the temperature of the titanium raw material to 1000 ° C. or less.
  • the temperature range at this time was 716 degreeC or more and 1000 degrees C or less.
  • the bulk density of the titanium raw material during hydrogenation was 1.2 g / cm 3 .
  • the block of titanium hydride was pulverized by a pulverizer / classifier to obtain a titanium hydride powder having a particle size of 10 ⁇ m to 150 ⁇ m.
  • the dehydrogenated titanium block was crushed.
  • the obtained titanium powder had a D95 particle size of 100 ⁇ m.
  • FIG. 1 An optical micrograph of the obtained titanium powder is shown in FIG.
  • the titanium powder was embedded in a resin, and after polishing the cross section of the sample, 16 arbitrary positions of 700 ⁇ m ⁇ 500 ⁇ m size were observed with an optical microscope at a magnification of 500 times.
  • the number of detected pores was 20 / mm 2 per unit area.
  • the pore area ratio was 0.11%.
  • Total MgCl 2 concentration is less than the total MgCl 2 concentration 0.0002Mass% produced using a titanium sponge material is less than 0.1mass%, the maximum thickness was used chips of 7mm as titanium raw material. That is, the internal MgCl 2 concentration of the titanium raw material was also 0.0002 mass% or less.
  • the atmosphere was heated to 650 ° C. with a heater and held for 120 minutes. Thereafter, hydrogen was supplied to cause a reaction of hydrogen storage exotherm, and heater control, Ar gas insertion and cooling device were operated, and hydrogenation was performed for 120 minutes while controlling the temperature of the titanium raw material to 1000 ° C. or less.
  • the temperature range at this time was 716 degreeC or more and 1000 degrees C or less.
  • the bulk density at the time of hydrogenation was 1.2 g / cm 3 .
  • the titanium hydride lump was pulverized by a pulverizer / classifier to obtain a titanium hydride powder having a particle size of 10 ⁇ m to 150 ⁇ m.
  • the lump of dehydrogenated titanium was crushed.
  • the obtained titanium powder had a D95 particle size of 100 ⁇ m.
  • titanium powder was produced in two ways: the concentration of iron, which is an impurity in the titanium raw material, being 200 mass ppm or less, and more than 200 mass ppm and 500 mass ppm or less.
  • the detected pores were 8 to 10 per mm 2 per unit area. In either case, the pore area ratio was 0.02%. For this reason, the amount of iron, which is an impurity, in other words, titanium purity is considered to have no correlation with pore behavior.
  • Example 3 90% Ti-6% Al-4% V (mass%) chips produced using a titanium sponge raw material with a total MgCl 2 concentration of 0.1 mass% or less and an alloy of 60% Al-40% V as a raw material Using.
  • the total MgCl 2 concentration of the titanium alloy chips used as the raw material was 0.0002 mass% or less, and the maximum thickness was 7 mm. That is, the internal MgCl 2 concentration of the titanium alloy chips was also 0.0002 mass% or less.
  • the atmosphere was heated to 650 ° C. with a heater and held for 120 minutes.
  • the bulk density at the time of hydrogenation was 1.2 g / cm 3 .
  • the block of titanium hydride was pulverized by a pulverizer / classifier to obtain a powder of 10 ⁇ m to 150 ⁇ m.
  • dehydrogenation treatment was performed under vacuum heat treatment furnace conditions, and the dehydrogenated titanium mass was crushed.
  • the obtained titanium powder had a D95 particle size of 100 ⁇ m.
  • the obtained titanium alloy powder was embedded in a resin and the cross section of the sample was polished, 16 arbitrary positions of 700 ⁇ m ⁇ 500 ⁇ m size were observed with an optical microscope at a magnification of 500 times. As a result, the detected pore was 9 per unit area. Pieces / mm 2 . The pore area ratio was 0.03%.
  • the titanium alloy powder obtained above was spheroidized by melting the surface with a high-frequency thermal induction plasma apparatus using Ar gas as a plasma gas.
  • the conditions for spheroidization are as shown in Table 1.
  • An optical micrograph of the obtained titanium alloy powder is shown in FIG.
  • the titanium alloy powder was embedded in a resin, and the cross section of the sample was magnified 500 times with an optical microscope, and 16 arbitrary positions of 700 ⁇ m ⁇ 500 ⁇ m size were observed.
  • the number of detected pores was 3 / mm 2 per unit area.
  • the pore area ratio was 0.01%. It was confirmed that the titanium alloy powder produced and crushed by the HDH method is useful as a raw material powder for spherical powder.
  • Example 4 Using as raw material 89% Ti-7% Al-4% V (mass%) chips produced using a sponge titanium material with a total MgCl 2 concentration of 0.1 mass% or less and an alloy of 70% Al-40% V. Using. The total MgCl 2 concentration of the titanium alloy chips used as the raw material was 0.0002 mass% or less, and the maximum thickness was 2 mm. That is, the internal MgCl 2 concentration of the titanium alloy chips was also 0.0002 mass% or less. After evacuating 300 kg of the raw material to 5 Pa or less, the atmosphere was heated to 650 ° C. with a heater and held for 120 minutes.
  • the bulk density at the time of hydrogenation was 1.2 g / cm 3 .
  • the block of titanium hydride was pulverized by a pulverizer / classifier to obtain a powder of 10 ⁇ m to 150 ⁇ m.
  • dehydrogenation treatment was performed under vacuum heat treatment furnace conditions, and the dehydrogenated titanium mass was crushed.
  • the obtained titanium powder had a D95 particle size of 100 ⁇ m.
  • the obtained titanium alloy powder was embedded in a resin and the cross section of the sample was polished, 16 arbitrary positions of 700 ⁇ m ⁇ 500 ⁇ m size were observed with an optical microscope at a magnification of 500 times. As a result, the detected pore was 9 per unit area. Pieces / mm 2 . The pore area ratio was 0.03%.
  • Titanium powder was produced under the same conditions as in Example 1 except that sponge titanium having an internal MgCl 2 concentration of 0.2 mass% was used as the titanium raw material. The total MgCl 2 concentration of the sponge titanium was 0.3 mass%. The obtained titanium powder was embedded in a resin, and the cross section of the sample was polished. Then, with an optical microscope, the magnification was 500 times, and 16 arbitrary places of 700 ⁇ m ⁇ 500 ⁇ m size were observed. As a result of analyzing the number of pores and the area ratio, the number of detected pores was 85 / mm 2 per unit area. The pore area ratio was 0.7%.
  • Titanium powder produced by the gas atomization method having the same particle size as in Example 1 was purchased, embedded in a resin, and the sample cross section was polished. Then, the magnification was 500 times with an optical microscope, and an arbitrary portion of 700 ⁇ m ⁇ 500 ⁇ m size was obtained. The location was observed. As a result of analyzing the number of pores and the area ratio, the number of detected pores was 130 / mm 2 per unit area. The pore area ratio was 1.0% (FIG. 5).

Abstract

Provided is a titanium powder which is reduced in pores in titanium particles. A titanium powder that is characterized in that the pore area ratio, which is the value obtained by dividing the cross-sectional area of pores in a cross-section of the titanium powder by the area of the cross-section, is 0.3% or less. A method for producing a titanium powder, which is a hydrogenation-dehydrogenation method comprising a hydrogenation step, a pulverization step and a dehydrogenation step to be performed on a titanium starting material, and which is characterized in that the concentration of all MgCl2 contained in the titanium starting material is 1.0 mass% or less, while the internal MgCl2 concentration is 0.1 mass% or less.

Description

チタン系粉およびその製造方法Titanium powder and method for producing the same
　本発明は、チタン系粉に関し、詳細には、水素化脱水素法（以下、ＨＤＨ法と称する）により製造する、従来にない、全く新規なチタン系粉およびその製造方法に関する。 The present invention relates to a titanium-based powder, and in particular, to an entirely new titanium-based powder produced by a hydrodehydrogenation method (hereinafter referred to as HDH method) and a method for producing the same.
　従来、チタン系粉中のポアについては、ほとんど工業的に注目されておらず、詳細にポア発生機構を研究する文献等は殆どない状態であった。近年、チタン系粉を用いた焼結体の密度向上要求や、チタン系粉から製造されるチタン製品への品質要求の高度化に伴い、チタン系粉中のポア低減要求が高まってきている。 Conventionally, pores in titanium-based powders have received little industrial attention, and there has been almost no literature or the like to study the pore generation mechanism in detail. In recent years, there has been an increasing demand for pore reduction in titanium-based powders along with the demand for density enhancement of sintered bodies using titanium-based powders and the advancement of quality requirements for titanium products manufactured from titanium-based powders.
　チタン系粉のポアを低減させる技術を開示した先行技術文献について調査を行ったものの、発見には至らなかった。チタン系粉の製造に関する先行技術文献としては、特許文献１及び特許文献２がある。なお、本明細書においては、チタン粉およびチタン合金粉を、チタン系粉という。 Investigated prior art documents disclosing the technology to reduce the pores of titanium powder, but did not find it. Prior art documents relating to the production of titanium-based powder include Patent Document 1 and Patent Document 2. In the present specification, titanium powder and titanium alloy powder are referred to as titanium-based powder.
特開平５－２４７５０３号公報JP-A-5-247503 特開平７－２７８６０１号公報Japanese Patent Laid-Open No. 7-278601
　本発明は上記の問題を解決することを目的とするものであり、すなわち、チタン系粉中のポアを低減させたチタン系粉を提供することにある。 The present invention aims to solve the above problems, that is, to provide a titanium-based powder with reduced pores in the titanium-based powder.
　上記のポアの少ないチタン系粉の製造を達成するため、本発明では、ポアの構造や発生メカニズムを詳細に解析した。その結果、チタン系粉の原料および製造方法を調整することで、ポアの発生個数が大幅に変化することを見出すとともに、ポアの発生はチタン系粉中にガスが存在する（またはしていた）ことにより、断面形状が略円形（球形）のポアが残存するとの解析結果に着目した。 In order to achieve the production of the above-mentioned titanium-based powder with less pores, in the present invention, the pore structure and generation mechanism were analyzed in detail. As a result, by adjusting the raw material and manufacturing method of the titanium-based powder, it was found that the number of pores significantly changed, and the generation of pores was (or had) gas in the titanium-based powder. As a result, attention was paid to the analysis result that pores having a substantially circular (spherical) cross-sectional shape remained.
　本発明の一実施形態によると、チタン系粉であって、チタン系粉の断面に占めるポアの断面積を前記チタン系粉の断面の面積で除したポア面積比が０．３パーセント以下であることを特徴とするチタン系粉が提供される。 According to an embodiment of the present invention, the pore area ratio of the titanium-based powder divided by the cross-sectional area of the titanium-based powder divided by the area of the cross-section of the titanium-based powder is 0.3% or less. A titanium-based powder is provided.
　チタン系粉がＨＤＨ粉であってもよい。 The titanium powder may be HDH powder.
　本発明の一実施形態によると、チタン系原料を用いた、水素化工程、粉砕工程、脱水素工程を含む水素化脱水素法によるチタン系粉の製造方法であって、前記チタン系原料に含有される全ＭｇＣｌ2の濃度が１．０ｍａｓｓ％以下であり、内部ＭｇＣｌ2濃度が０．１ｍａｓｓ％以下であることを特徴とするチタン系粉の製造方法が提供される。 According to one embodiment of the present invention, a titanium-based powder is produced by a hydrodehydrogenation method including a hydrogenation step, a pulverization step, and a dehydrogenation step using a titanium-based material, which is contained in the titanium-based material. the concentration of total MgCl 2 which is not more than 1.0 mass%, the production method of the titanium-based powder, wherein the internal MgCl 2 concentration is not more than 0.1mass% is provided.
　チタン系原料の最大厚みが２０ｍｍ以下であってもよい。 The maximum thickness of the titanium-based raw material may be 20 mm or less.
　粉砕工程において、水素化チタン系粉末はＤ９５粒径が３００μｍ以下に粉砕されてもよい。 In the pulverization step, the titanium hydride-based powder may be pulverized to a D95 particle size of 300 μm or less.
　水素化工程において、チタン系原料の温度を７１６℃以上１０５０℃以下の範囲内で９０分以上の時間をかけて水素化してもよい。 In the hydrogenation step, the temperature of the titanium-based raw material may be hydrogenated over a period of 90 minutes or more within the range of 716 ° C. or more and 1050 ° C. or less.
　チタン系粉中のポア発生は、ガスと密接な関係がある。チタン系粉中にガスを巻き込ませないことや、チタン系粉内部でガスを発生させないこと、もしくは、発生したガスをチタン系粉内部から速やかに取り除くことで、ポアが存在するチタン系粉の個数の大幅な低減が可能である。 The generation of pores in titanium powder is closely related to gas. Number of titanium-based powders with pores by preventing gas from being involved in the titanium-based powder, generating no gas inside the titanium-based powder, or quickly removing the generated gas from inside the titanium-based powder. Can be significantly reduced.
画像処理の方法を示すための図で、特に内包されたポアを示す図である。It is a figure for demonstrating the method of an image processing, and is a figure which shows the pore included especially. 画像処理の方法を示すための図で、特にオープンになっているポアを示す図である。It is a figure for demonstrating the method of an image processing, and is a figure which shows the pore especially opened. 実施例１に係るチタン粉の光学顕微鏡写真である。2 is an optical micrograph of titanium powder according to Example 1. 実施例３に係るチタン粉の光学顕微鏡写真である。4 is an optical micrograph of titanium powder according to Example 3. 比較例２に係るチタン粉の光学顕微鏡写真において画像処理を行った際の写真である。It is the photograph at the time of performing image processing in the optical microscope photograph of the titanium powder which concerns on the comparative example 2.
　チタン粉は、現在、ほとんどがクロール法にて製造されるスポンジチタンを原料としている。また、経済性、資源保護の観点から、スクラップを原料として活用する場合もある。 Titanium powder is currently made from titanium sponge, which is mostly manufactured by the crawl method. In some cases, scrap is used as a raw material from the viewpoint of economy and resource protection.
　［クロール法の説明］
　クロール法とは、チタン鉱石を塩素化して得られる四塩化チタン（ＴｉＣｌ4）をマグネシウム（Ｍｇ）で還元して金属チタンを得る方法である。 [Description of the crawl method]
The crawl method is a method of obtaining titanium metal by reducing titanium tetrachloride (TiCl 4 ) obtained by chlorinating titanium ore with magnesium (Mg).
　クロール法においては、還元工程（ＴｉＣｌ4＋２Ｍｇ→Ｔｉ＋２ＭｇＣｌ2）で生じるＭｇＣｌ2がスポンジチタンと共存するため、そのＭｇＣｌ2を分離工程で除去した後のスポンジチタンが使用される。ところが、そのスポンジチタンをよく調べると、完全にＭｇＣｌ2が除去できているわけではなく、スポンジチタンの表面に付着しているＭｇＣｌ2（表面ＭｇＣｌ2）と、スポンジチタンの内部に閉じ込められ外部と遮断されたＭｇＣｌ2（内部ＭｇＣｌ2）の２種類が残存していることが分かった。 In the crawl method, since the MgCl 2 generated in the reduction step (TiCl 4 + 2Mg → Ti + 2MgCl 2 ) coexists with the sponge titanium, the titanium sponge after the MgCl 2 is removed in the separation step is used. However, if the sponge titanium is examined closely, the MgCl 2 is not completely removed, but the MgCl 2 (surface MgCl 2 ) adhering to the surface of the titanium sponge and the inside of the titanium sponge are confined to the outside. It was found that two types of blocked MgCl 2 (internal MgCl 2 ) remained.
　分離工程で十分取りきれずスポンジチタンの表面に残存するＭｇＣｌ2（表面ＭｇＣｌ2）は、再度、減圧下で熱を加えることにより、除去することができる。一方、減圧下で熱を加えた後のスポンジチタンを切断して内部を調べたところ、スポンジチタンの内部に閉じ込められたＭｇＣｌ2（内部ＭｇＣｌ2）は、この方法では取り除くことができないことがわかった。 MgCl 2 (surface MgCl 2 ) that cannot be sufficiently removed in the separation step and remains on the surface of the sponge titanium can be removed by applying heat again under reduced pressure. On the other hand, when the sponge titanium after applying heat under reduced pressure was cut and the inside was examined, it was found that MgCl 2 (internal MgCl 2 ) confined in the sponge titanium could not be removed by this method. It was.
　［アトマイズ法チタン粉製造方法の説明］
　チタン粉の製造方法は、アトマイズ法とＨＤＨ法に大別される。アトマイズ法では、チタン原料を溶融させた後、Ａｒガス中で液状化したチタンを細かい液状の粒にすると同時に、急冷し、固化させることでチタン粉を製造する。 [Description of atomized titanium powder production method]
The method for producing titanium powder is roughly divided into an atomizing method and an HDH method. In the atomization method, after melting a titanium raw material, titanium powder liquefied in Ar gas is made into fine liquid particles, and at the same time, rapidly cooled and solidified to produce titanium powder.
　本発明者の研究調査では、アトマイズ法においては、チタン粉中にポアが発生する２つの機構があると結論づけた。1つ目は、チタン原料の内部に存在するＭｇＣｌ2（内部ＭｇＣｌ2）が一気にガス化し、直ちに急冷されることにより、ガス化したＭｇＣｌ2が液状化したチタンの粒内部に閉じ込められチタン粉中にポアが発生する機構である。２つ目は、液状化したチタンの粒がＡｒガスもしくは気化したＭｇＣｌ2ガスを巻き込んで凝固することにより、チタン粉中にポアが発生する機構である。このため、本発明の目的を達成するにはＨＤＨ法が適するとの結論に至った。 In the research conducted by the present inventor, it was concluded that there are two mechanisms for generating pores in titanium powder in the atomization method. First, MgCl 2 (internal MgCl 2 ) present inside the titanium raw material is gasified at once, and immediately cooled rapidly, so that the gasified MgCl 2 is confined within the liquefied titanium grains and in the titanium powder. It is a mechanism that generates pores. The second is a mechanism in which pores are generated in the titanium powder when the liquefied titanium grains are solidified by involving Ar gas or vaporized MgCl 2 gas. For this reason, it was concluded that the HDH method is suitable for achieving the object of the present invention.
　［ＨＤＨ法チタン粉製造方法の説明］
　ＨＤＨ法とは、チタン原料を一旦水素化し、脆いＴｉＨ2を形成した後、粉砕し、脱水素することでチタン粉を得る方法である。すなわち、水素化～粉砕～脱水素～解砕の工程によりチタン粉（ＨＤＨ粉）を製造する方法である。上記解砕工程は任意であるがチタン粉（ＨＤＨ粉）の製造では解砕工程を行うことが好ましい。 [Description of HDH process titanium powder production method]
The HDH method is a method in which a titanium raw material is once hydrogenated to form brittle TiH 2 , and then pulverized and dehydrogenated to obtain titanium powder. That is, it is a method for producing titanium powder (HDH powder) by the steps of hydrogenation, pulverization, dehydrogenation, and pulverization. Although the said crushing process is arbitrary, it is preferable to perform a crushing process in manufacture of titanium powder (HDH powder).
　この際、水素化の工程ではチタン原料を真空置換可能な水素化炉に装入し、４００℃以上の温度で、水素ガス雰囲気中で水素化処理を行い、水素ガス雰囲気からＡｒガス雰囲気に置換することにより水素化チタンの塊状体を得る。チタン原料は、水素化の工程によって水素脆化される。 At this time, in the hydrogenation process, the titanium raw material is charged into a hydrogenation furnace capable of vacuum replacement, and hydrogenated in a hydrogen gas atmosphere at a temperature of 400 ° C. or higher, and the hydrogen gas atmosphere is replaced with an Ar gas atmosphere. By doing so, a block of titanium hydride is obtained. The titanium raw material is hydrogen embrittled by a hydrogenation process.
　次は粉砕の工程である。粉砕の工程では、水素化チタンの塊状体を機械粉砕して、機械的な破面すなわち粉砕面を有する水素化チタン粉末にする。得られた水素化チタン粉末は、分級および／または篩別して水素化チタンの微粉を除去する。水素化チタンの機械的粉砕には、ボールミル、振動ミルなどの粉砕装置が使用でき、水素化チタン粉末の粒度調整には円形振動篩、気流分級機などの篩別分級装置を用いてもよい。 Next is the crushing process. In the pulverization step, the titanium hydride lump is mechanically pulverized into a titanium hydride powder having a mechanical fracture surface, that is, a pulverized surface. The obtained titanium hydride powder is classified and / or sieved to remove fine powder of titanium hydride. For mechanical pulverization of titanium hydride, a pulverizer such as a ball mill or a vibration mill can be used. For adjusting the particle size of the titanium hydride powder, a sieve classification device such as a circular vibration sieve or an airflow classifier may be used.
　脱水素化工程では、上記の水素化チタン粉末を容器に充填して、真空加熱型の脱水素炉に装入し、例えば１０-3Ｔｏｒｒ（０．１３Ｐａ）以下の真空中で、４５０℃以上の温度に加熱して脱水素することで脱水素チタン粉末にする。また、必要に応じてＡｒガスを挿入する。 In the dehydrogenation step, the titanium hydride powder is filled in a container and charged in a vacuum heating type dehydrogenation furnace, for example, 450 ° C. or higher in a vacuum of 10 −3 Torr (0.13 Pa) or lower. To dehydrogenated titanium powder by heating to a temperature of Moreover, Ar gas is inserted as needed.
　解砕工程では、脱水素工程で仮焼結した脱水素チタンの塊状体の仮焼結部分を解きほぐし、粉砕後の粉砕面または解砕面を有するチタン粉形状に戻す。 In the pulverization step, the pre-sintered portion of the dehydrogenated titanium block pre-sintered in the dehydrogenation step is unwound and returned to a titanium powder shape having a pulverized or crushed surface after pulverization.
　［ＨＤＨ法でのポア発生機構の説明］
　本発明者は、ＨＤＨ法の各製造工程における条件をポアの観点から詳細に研究調査し、いかに、ポアの発生を防ぐかを調べた。ＨＤＨ法では、各製造工程中でチタンが溶融され液化されることが無ければ、雰囲気中のＡｒガスが巻き込まれてポアの原因となることはない。ＨＤＨ法での熱処理は、水素化と脱水素化の２工程であることから、いずれも融点以下で行えばよいことになる。ただし、一般的にチタン材を入れる容器としてはステンレス鋼が使用されることから、ステンレス鋼に含まれる鉄とチタンとが接触して、両者の温度が鉄とチタンとの共晶温度以上になるとチタンが液体となり、上記目的にそぐわなくなる。その為、本発明者は、ポアの発生を防ぐためにはチタンを鉄とチタンとの共晶温度以下で制御し、チタンの液化を防ぐ必要があることを見出した。すなわち、上限温度を制御することが本発明の重要な構成要素になる。 [Description of pore generation mechanism in HDH method]
The present inventor has studied and investigated in detail the conditions in each manufacturing process of the HDH method from the viewpoint of pores, and investigated how to prevent the generation of pores. In the HDH method, if the titanium is not melted and liquefied in each manufacturing process, Ar gas in the atmosphere is not involved and does not cause pores. Since the heat treatment by the HDH method is two steps of hydrogenation and dehydrogenation, both may be performed at a melting point or lower. However, since stainless steel is generally used as a container for titanium material, when the iron and titanium contained in the stainless steel come into contact with each other, the temperature of both exceeds the eutectic temperature of iron and titanium. Titanium becomes liquid and does not meet the above purpose. Therefore, the present inventor has found that in order to prevent the generation of pores, it is necessary to control titanium below the eutectic temperature of iron and titanium to prevent liquefaction of titanium. That is, controlling the upper limit temperature is an important component of the present invention.
　例えば、特許文献１及び特許文献２では、「６５０℃まで真空雰囲気下に昇温した」としか記載がなく、その後の水素ガス導入後のチタン材の温度制御については記載がない。チタンを水素化する水素化反応は発熱反応のため、最初は、例えば真空炉内で、６５０℃で水素吸収を行わせるが、その後は自発的に温度が上昇する。このため、局所部も含めいずれの場所も共晶温度以下になるようチタン材料の容器への入れ方、水素およびＡｒ投入量、投入時間、および各部位の温度を常時観察しながら温度上昇を抑えるため冷却する等、細かな制御をする必要がある。 For example, in Patent Document 1 and Patent Document 2, there is only a description that “the temperature is raised to 650 ° C. in a vacuum atmosphere”, and there is no description about the temperature control of the titanium material after the subsequent introduction of hydrogen gas. Since the hydrogenation reaction for hydrogenating titanium is an exothermic reaction, hydrogen absorption is first performed at 650 ° C., for example, in a vacuum furnace, and then the temperature rises spontaneously. For this reason, the temperature rise is suppressed while constantly observing how to put the titanium material into the container, the amount of hydrogen and Ar charged, the charging time, and the temperature of each part so that any place including the local part is below the eutectic temperature. Therefore, it is necessary to perform fine control such as cooling.
　常圧下でのＭｇＣｌ2の沸点は１４１２℃であり、この温度においては、チタン原料の内部に閉じ込められたＭｇＣｌ2（内部ＭｇＣｌ2）は気体化する。一方、チタンの融点は１６６８℃であるため、１４１２℃では、チタンは固体の状態で存在する。気体化された内部ＭｇＣｌ2は、固体の状態に比べて体積が大きくなり、これが原因でチタンの内部では非常に高圧な状態が形成される。この気体化された内部ＭｇＣｌ2による高圧状態は、水素化によって脆くなった水素化チタンに亀裂を発生させ、そこからＭｇＣｌ2を水素化チタン外部に排出されることが可能である。 The boiling point of MgCl 2 under normal pressure is 1412 ° C. At this temperature, MgCl 2 (internal MgCl 2 ) confined inside the titanium raw material is gasified. On the other hand, since the melting point of titanium is 1668 ° C., titanium exists in a solid state at 1412 ° C. The gasified internal MgCl 2 has a larger volume than the solid state, and this causes a very high pressure state to be formed inside the titanium. This high-pressure state due to the gasified internal MgCl 2 can cause cracks in the titanium hydride that has become brittle by hydrogenation, from which MgCl 2 can be discharged to the outside of the titanium hydride.
　しかし、前記したように、ＨＤＨ法においては、チタン材を入れる容器はステンレス鋼の場合が多く、鉄とチタンの共晶温度（１０８５℃）以上にはあげられない。本発明では、この制限された温度を順守し、かつ、ポアの原因となるＭｇＣｌ2を取り除く従来にない制御方法を見出し、本発明を完成させた。つまり、チタン原料の温度を最低でもＭｇＣｌ2の融点（７１４℃）以上の温度にしてＭｇＣｌ2を液相とし、ＭｇＣｌ2の体積を固体の状態に比べて膨張させる。このとき、チタンは固体の状態で存在するため、内部ＭｇＣｌ2は固体の状態に比べて液体の状態のほうが体積が大きくなり、これが原因でチタンの内部では非常に高圧な状態が形成される。この液相の内部ＭｇＣｌ2による高圧状態は、水素化によって脆くなった水素化チタンに亀裂を発生させる。亀裂によりチタン外部に露出した液相のＭｇＣｌ2は、徐々に蒸発により気化できるようにする。この場合の炉内の温度及び加熱時間（温度の維持時間）の制御は、水素化するチタン原料の厚みや水素化時間も考慮して決定される。これが、例えば、チタンが脆化する前に、蒸発したＭｇＣｌ2にてチタン内部の圧力が高まると、高温ではチタンは軟化し容易に変形する為、チタン内部に球状のポアを形成させる結果となってしまい、本発明とは逆方向になる。例えば、本発明においては、７１６℃以上１０５０℃以下の範囲で９０分以上の時間をかけることによって、チタン原料の内部に存在するＭｇＣｌ2はチタンの亀裂から蒸発し、併せてチタンの水素化も実現することができる。理論的には、チタン原料の温度をＭｇＣｌ2の融点（７１４℃）以上から鉄とチタンの共晶温度（１０８５℃）未満の範囲で設定することができるが、上記温度範囲とすることでより確実な温度制御を行うことができる。 However, as described above, in the HDH method, the container in which the titanium material is put is often stainless steel, and cannot be raised above the eutectic temperature of iron and titanium (1085 ° C.). In the present invention, an unprecedented control method that obeys this limited temperature and removes MgCl 2 that causes pores has been found, and the present invention has been completed. That is, the temperature of the titanium raw material temperature of MgCl 2 melting point (714 ° C.) or higher for a minimum the MgCl 2 liquid phase, is expanded compared to the volume of MgCl 2 in the solid state. At this time, since titanium exists in a solid state, the volume of the internal MgCl 2 is larger in the liquid state than in the solid state, and this causes a very high pressure state to be formed inside the titanium. This high-pressure state due to internal MgCl 2 in the liquid phase causes cracks in titanium hydride that has become brittle by hydrogenation. The liquid phase MgCl 2 exposed to the outside of the titanium due to cracks is gradually vaporized by evaporation. In this case, the temperature in the furnace and the control of the heating time (temperature maintenance time) are determined in consideration of the thickness of the titanium raw material to be hydrogenated and the hydrogenation time. For example, if the pressure inside the titanium is increased by evaporated MgCl 2 before the titanium becomes brittle, the titanium softens and deforms easily at a high temperature, resulting in the formation of spherical pores inside the titanium. This is the opposite of the present invention. For example, in the present invention, by taking 90 minutes or more in the range of 716 ° C. or more and 1050 ° C. or less, MgCl 2 present in the titanium raw material evaporates from the cracks of titanium, and also hydrogenation of titanium is performed. Can be realized. Theoretically, the temperature of the titanium raw material can be set in the range from the melting point of MgCl 2 (714 ° C.) or higher to the eutectic temperature of iron and titanium (1085 ° C.). Reliable temperature control can be performed.
　なお、本実施形態に係るＨＤＨ法においては、温度を制御することで原料のチタンが溶融しないようにする。しかしながら、チタン原料の表面にＭｇＣｌ2が付着している場合には、ＨＤＨ法の工程中にＭｇＣｌ2が気化することから、表面のＭｇＣｌ2を取り除くために高真空にすることが好ましい。本実施形態に係るＨＤＨ法においては、チタン原料と共に持ち込まれる表面に付着したＭｇＣｌ2量を低減するとともに、温度、時間、真空度、Ａｒ置換等、コストを考え最適化することが重要である。 In the HDH method according to the present embodiment, the raw material titanium is prevented from melting by controlling the temperature. However, when MgCl 2 adheres to the surface of the titanium raw material, MgCl 2 is vaporized during the HDH process, and therefore it is preferable to use a high vacuum to remove the surface MgCl 2 . In the HDH method according to the present embodiment, it is important to reduce the amount of MgCl 2 adhering to the surface brought together with the titanium raw material, and to optimize it in consideration of costs such as temperature, time, vacuum degree, and Ar substitution.
　本実施形態に係る水素化工程では、ポアを発生させないようにし、かつ、チタン内部に存在するＭｇＣｌ2（内部ＭｇＣｌ2）を除去するため、本発明で見いだされた上記機構を具現化する水素化工程とする。十分な時間をかけて水素化による脆化を行えば、ＭｇＣｌ2を排出させることは可能であるが、工業的には生産性及びコスト的に適切ではない。 In the hydrogenation process according to the present embodiment, hydrogenation that embodies the above-described mechanism found in the present invention to prevent generation of pores and to remove MgCl 2 (internal MgCl 2 ) existing inside titanium. Let it be a process. If embrittlement by hydrogenation is performed for a sufficient time, MgCl 2 can be discharged, but it is not industrially suitable in terms of productivity and cost.
　研究調査の結果、チタン原料の表面に付着するＭｇＣｌ2量を制御すること以上に、チタン原料の内部に存在するＭｇＣｌ2量を制御することが生産性及びコストに大きく影響することが判明した。種々の実験をしたところ、チタン原料の全ＭｇＣｌ2濃度を１．０ｍａｓｓ％以下に抑えることが必要であることが判明した。そして、チタン原料の全ＭｇＣｌ2濃度は、０．０５ｍａｓｓ％以下に抑えることが好ましく、０．００１ｍａｓｓ％以下に抑えることがより好ましい。特に、チタン原料の内部に存在するＭｇＣｌ2濃度（内部ＭｇＣｌ2濃度）を０．５ｍａｓｓ％以下にすれば、ＨＤＨ法においてチタン原料の温度をＭｇＣｌ2の融点（７１４℃）以上から鉄とチタンの共晶温度（１０８５℃）未満の範囲で維持する時間が９０分であってもポアの原因となるＭｇＣｌ2を効率よく取り除くことができることがわかった。チタン原料の内部に存在するＭｇＣｌ2濃度（内部ＭｇＣｌ2濃度）を０．１ｍａｓｓ％以下とすることでさらに明確に効果が表れる。本発明ではチタン原料の内部に閉じ込められたＭｇＣｌ2濃度（内部ＭｇＣｌ2濃度）を０．１ｍａｓｓ％以下とすることが好ましく、０．００１ｍａｓｓ％以下とすることがより好ましい。 As a result of research, it has been found that controlling the amount of MgCl 2 present inside the titanium raw material has a significant effect on productivity and cost, in addition to controlling the amount of MgCl 2 adhering to the surface of the titanium raw material. As a result of various experiments, it was found that the total MgCl 2 concentration of the titanium raw material needs to be suppressed to 1.0 mass% or less. The total MgCl 2 concentration of the titanium raw material is preferably suppressed to 0.05 mass% or less, more preferably 0.001 mass% or less. In particular, if the MgCl 2 concentration (internal MgCl 2 concentration) present in the titanium raw material is 0.5 mass% or less, the temperature of the titanium raw material is increased from the melting point (714 ° C.) of MgCl 2 to the iron and titanium in the HDH method. It has been found that MgCl 2 that causes pores can be efficiently removed even if the time for maintaining in the range below the eutectic temperature (1085 ° C.) is 90 minutes. The effect is more clearly shown by setting the MgCl 2 concentration (internal MgCl 2 concentration) present in the titanium raw material to 0.1 mass% or less. In the present invention, the MgCl 2 concentration (internal MgCl 2 concentration) confined inside the titanium raw material is preferably 0.1 mass% or less, and more preferably 0.001 mass% or less.
　〔原料でのポア抑制方法〕
　なお、本発明のＨＤＨ法では、チタンが溶融しないため、Ａｒガス等の巻き込みによるポアの発生はない。 [Method of suppressing pores in raw materials]
In the HDH method of the present invention, since titanium does not melt, there is no generation of pores due to inclusion of Ar gas or the like.
　チタン原料の全ＭｇＣｌ2濃度を１．０ｍａｓｓ％以下に抑え、さらにはチタン原料内部に閉じ込められたＭｇＣｌ2濃度（内部ＭｇＣｌ2濃度）を０．１ｍａｓｓ％以下に抑える方法としては、コストはかかるものの事前にスポンジチタンをさらに細かくし、再度、真空中で熱処理する方法も有効である。 Although it is costly as a method of suppressing the total MgCl 2 concentration of the titanium raw material to 1.0 mass% or less and further suppressing the MgCl 2 concentration (internal MgCl 2 concentration) confined inside the titanium raw material to 0.1 mass% or less It is also effective to make the titanium sponge finer in advance and heat-treat in vacuum again.
　また、チタン原料は、その最大厚みが２０ｍｍ以下、より好ましくは１０ｍｍ以下であるとよい。チタン原料の最大厚みが２０ｍｍ以下であることにより、水素化時に水素が充分に原料内部に行き渡り、チタンを脆化させ亀裂を速やかに生じさせるためである。 Further, the titanium raw material has a maximum thickness of 20 mm or less, more preferably 10 mm or less. This is because when the maximum thickness of the titanium raw material is 20 mm or less, hydrogen sufficiently spreads inside the raw material during hydrogenation, embrittles titanium and promptly causes cracks.
　［全ＭｇＣｌ2濃度の定義］
　全ＭｇＣｌ2の濃度の測定方法を説明する。対象とするチタン原料の塩素濃度を硝酸銀滴定法（ＪＩＳ　Ｈ　１６１５）により測定し、その塩素濃度の値よりＭｇＣｌ2濃度に換算し、これをチタン原料に含まれるＭｇＣｌ2濃度（全ＭｇＣｌ2濃度）とする。 [Definition of total MgCl 2 concentration]
A method for measuring the concentration of total MgCl 2 will be described. Chlorine concentration of the target titanium raw material is measured by silver nitrate titration method (JIS H 1615), converted to MgCl 2 concentration from the value of the chlorine concentration, and this is the MgCl 2 concentration (total MgCl 2 concentration) contained in the titanium raw material. And
　［内部ＭｇＣｌ2濃度の定義］
　内部ＭｇＣｌ2の濃度の測定方法を説明する。まず、対象とするチタン原料を減圧下（５０ｐａ以下）にて、約７５０℃×１時間の熱処理をすることにより表面のＭｇＣｌ2を飛ばす。その後、本材料の塩素濃度を硝酸銀滴定法（ＪＩＳ　Ｈ　１６１５）により測定し、その塩素濃度の値よりＭｇＣｌ2濃度に換算し、これをチタン原料の内部に閉じ込められ存在するＭｇＣｌ2濃度（内部ＭｇＣｌ2濃度）とする。 [Definition of internal MgCl 2 concentration]
A method for measuring the concentration of internal MgCl 2 will be described. First, the target titanium raw material is heat-treated at about 750 ° C. for 1 hour under reduced pressure (50 pa or less), thereby removing MgCl 2 on the surface. Thereafter, the chlorine concentration of this material is measured by a silver nitrate titration method (JIS H 1615), converted to the MgCl 2 concentration from the value of the chlorine concentration, and this concentration is confined inside the titanium raw material (the internal MgCl 2 concentration). 2 concentration).
　［チタン粉の大きさの説明］
　粉砕工程にて、水素化された水素化チタンを粉砕し細かくした、粉砕面を有する水素化チタン粉とすることで、水素化チタンに残存しているポアが起点となり割れて、開放される確率をさらに高めることができる。ポアが開放される確率は、水素化チタン粉の粒径をより細かくすればより高くなる。しかしながら、工業的にはコストおよび時間の制限があることから、水素化チタン粉の粒径は３００μｍ以下、好ましくは１５０μｍ以下であればよい。ここで、ＨＤＨ法で製造され粉砕された水素化チタン粉の粒径は分布を持っており、全水素化チタン粉の粒径の９５％以上が上記値以下であればよい。すなわち、水素化チタン粉末のＤ９５粒径は３００μｍ以下であり、好ましくは１５０μｍ以下にまで抑えるとより一層効果がある。Ｄ９５粒径の下限側は特に限定されないがあえて一例を挙げると７０μｍ以上としてもよく、８０μｍ以上としてもよい。本発明においてＤ９５は、レーザー回折・散乱法により求められる粒度分布測定において、体積基準の積算分布が、それぞれ、９５％となる粒径を指す。詳細には、ＪＩＳ　Ｚ８８２５：２０１３に基づき測定する。 [Description of the size of titanium powder]
In the pulverization process, the hydrogenated titanium hydride is pulverized into fine titanium hydride powder with a pulverized surface. Can be further enhanced. The probability that the pores are released increases as the particle size of the titanium hydride powder is made finer. However, since there are cost and time restrictions industrially, the particle size of the titanium hydride powder may be 300 μm or less, preferably 150 μm or less. Here, the particle size of the titanium hydride powder produced and pulverized by the HDH method has a distribution, and 95% or more of the particle size of the total titanium hydride powder may be less than the above value. That is, the titanium hydride powder has a D95 particle size of 300 μm or less, preferably 150 μm or less. Although the lower limit side of the D95 particle size is not particularly limited, for example, it may be 70 μm or more, or 80 μm or more. In the present invention, D95 indicates a particle size at which the volume-based cumulative distribution is 95% in the particle size distribution measurement obtained by the laser diffraction / scattering method. In detail, it measures based on JISZ8825: 2013.
　また、ＨＤＨ法で製造され解砕されたチタン粉の全チタン粒径の９５％以上が１５０μｍ以下であればよい。 Further, 95% or more of the total titanium particle diameter of the titanium powder produced and crushed by the HDH method may be 150 μm or less.
　〔球状化工程への適用〕
　上記したＨＤＨ法で製造されたチタン粉では、ＭｇＣｌ2の残留が少ない。このため、本発明のＨＤＨ法で製造されたチタン粉は、チタン粉の表面を溶融させ（例えばプラズマ溶融）、粉砕面または解砕面である角ばった表面を球状化させて、球状粉を得るための原料粉末として好適である。ＨＤＨ法で製造され解砕されたチタン粉は、凹凸構造を有する粉砕面または解砕面を有しているため、その広い表面積により、プラズマに導入した際の溶融を促進させることができる。なお、球状化する為にチタン粉表面を溶融させてもＡｒ等のプラズマガスの巻き込みはなく、新たなポアは抑制できる。 [Application to spheronization process]
In the titanium powder produced by the HDH method described above, there is little residual MgCl 2 . For this reason, the titanium powder produced by the HDH method of the present invention melts the surface of the titanium powder (for example, plasma melting), and spheroidizes the angular surface that is the pulverized or crushed surface to obtain a spherical powder. Therefore, it is suitable as a raw material powder. Since the titanium powder produced and crushed by the HDH method has a pulverized surface or a pulverized surface having a concavo-convex structure, melting when introduced into plasma can be promoted by its large surface area. In addition, even if the titanium powder surface is melted for spheroidization, plasma gas such as Ar is not involved, and new pores can be suppressed.
　以上、ＨＤＨ法におけるポア発生を抑えるためには、上記したように温度、時間、水素吹込み量、材料形状、ＭｇＣｌ2持ち込み量（全体の量と封じ込められたＭｇＣｌ2の量）を適切に制御することにより達成できることを見出し、本発明を完成するに至った。 As described above, in order to suppress the generation of pores in the HDH method, the temperature, time, hydrogen blowing amount, material shape, and MgCl 2 carry-in amount (total amount and amount of contained MgCl 2 ) are appropriately controlled as described above. As a result, the present inventors have found that this can be achieved, and have completed the present invention.
　本実施形態においては、チタン粉に基づいて説明した。しかしながら、チタンに５０質量％以下のＡｌやＶ等の元素を含有するチタン合金粉においても、ＨＤＨ法で温度を制御することで原料のチタン合金が溶融しないようにし、チタン粉と同様の効果を得ることができる。チタンに含有させる元素は２０質量％以下が好ましく、１５質量％以下がさらに好ましい。チタン合金粉は複数種類の元素を含んでもよい。例えば、チタン合金粉はＴｉ－Ａｌ－Ｖ合金粉としてもよい。この場合、該Ｔｉ－Ａｌ－Ｖ合金粉は、Ａｌ含有量を５．５～７．５質量％、Ｖ含有量を３．５～４．５質量％とすることができる。 In the present embodiment, the explanation is based on titanium powder. However, even in titanium alloy powder containing 50% by mass or less of elements such as Al and V in titanium, the titanium alloy as a raw material is prevented from melting by controlling the temperature by the HDH method, and the same effect as titanium powder is obtained. Obtainable. The element contained in titanium is preferably 20% by mass or less, and more preferably 15% by mass or less. The titanium alloy powder may contain a plurality of types of elements. For example, the titanium alloy powder may be Ti—Al—V alloy powder. In this case, the Ti—Al—V alloy powder can have an Al content of 5.5 to 7.5 mass% and a V content of 3.5 to 4.5 mass%.
［断面のポア面積比の説明］
　本実施形態に係るチタン系粉の製造方法によって、チタン系粉の任意の断面を観察し現れた内包されたポア（以下、内部ポア）の断面積を、チタン系粉の断面の面積で割った値（断面のポア面積比）が０．３パーセント以下であることを実現することができる。また、本発明において製造されたチタン系粉は、チタン系粉の任意の断面を観察し現れた内部ポアの数が単位面積当たり２０個／ｍｍ2以下であることが好ましい。ここでチタン系粉断面のポア面積比が０．３パーセント以下とは、チタン系粉末を樹脂に埋め込み研磨した後、断面を光学顕微鏡で、倍率５００倍で、７００μｍ×５００μｍサイズの任意の箇所を１６箇所観察した際に、画像処理により輝度９０～２５０の範囲の像として観察された内部ポアの断面積を、粉の総断面積で除した値が０．３パーセント以下であることを意味する。内部ポアの数とは、上記観察した際に、画像処理により輝度９０～２５０の範囲の像として観察された、内部ポアの数を意味する。なお、いずれの観察の際にも、画像処理により長径１０μｍ以下の粉は除外する。また、画像処理では、内部ポアに見えても元画像から明らかにオープンになっているポアは除外した（図１は画像処理前の写真であり、図２は画像処理後の写真である）。また、明らかに２つのポアが接している場合であっても、画像処理で接続した１個の内部ポアである限り１個として計算した。本発明においては、上記断面のポア面積比が０．３パーセント以下となるから、本発明に係る製造方法で製造されたチタン粉はポアが少なければならない技術分野（たとえば、航空機材料等）において使用することに好適である。他方、断面のポア面積比が０．３パーセントを超えると、該技術分野で使用することが難しいということが判明した。 [Description of cross-sectional pore area ratio]
By the method for producing a titanium-based powder according to the present embodiment, the cross-sectional area of an embedded pore (hereinafter referred to as an internal pore) that appeared after observing an arbitrary cross-section of the titanium-based powder was divided by the area of the cross-section of the titanium-based powder. It can be realized that the value (pore area ratio of the cross section) is 0.3% or less. In addition, the titanium-based powder produced in the present invention preferably has an internal pore number of 20 / mm 2 or less per unit area that appears when an arbitrary cross section of the titanium-based powder is observed. Here, the pore area ratio of the titanium-based powder cross section is 0.3% or less. After embedding and polishing the titanium-based powder in a resin, the cross section is measured with an optical microscope at a magnification of 500 times and an arbitrary portion of 700 μm × 500 μm size. It means that the value obtained by dividing the cross-sectional area of the internal pores observed as an image in the range of luminance 90 to 250 by image processing when observed at 16 locations is 0.3% or less. . The number of internal pores means the number of internal pores observed as an image having a luminance in the range of 90 to 250 by image processing when observed. In any observation, powder having a major axis of 10 μm or less is excluded by image processing. Also, in the image processing, pores that are clearly open from the original image even though they look like internal pores were excluded (FIG. 1 is a photograph before image processing, and FIG. 2 is a photograph after image processing). In addition, even when two pores are clearly in contact with each other, the calculation is performed as one as long as it is one internal pore connected by image processing. In the present invention, since the pore area ratio of the cross section is 0.3% or less, the titanium powder produced by the production method according to the present invention is used in a technical field (for example, aircraft materials) where the pores must be small. It is suitable to do. On the other hand, it was found that when the pore area ratio of the cross section exceeds 0.3 percent, it is difficult to use in the technical field.
　［実施例１］
　チタン原料としてスポンジチタンを使用した。使用したチタン原料は、全ＭｇＣｌ2濃度および内部ＭｇＣｌ2濃度とも０．０５ｍａｓｓ％以下で、直径は１／２インチ以下のものを使用した。 [Example 1]
Sponge titanium was used as a titanium raw material. The titanium raw materials used were those having a total MgCl 2 concentration and an internal MgCl 2 concentration of 0.05 mass% or less and a diameter of 1/2 inch or less.
　原料３００ｋｇを５Ｐａ以下に真空引きした後、ヒーターで雰囲気を６５０℃に加熱し、１２０分間保持した。その後、水素を供給して水素吸蔵発熱の反応を起こさせるとともにヒーターの制御やＡｒガス挿入および冷却装置を稼働させ、チタン原料が１０００℃以下になるように温度制御しながら１２０分間水素化した。このときの温度範囲は７１６℃以上１０００℃以下であった。 After vacuuming 300 kg of the raw material to 5 Pa or less, the atmosphere was heated to 650 ° C. with a heater and held for 120 minutes. Thereafter, hydrogen was supplied to cause a reaction of hydrogen storage exotherm, and the heater was controlled, the Ar gas was inserted and the cooling device was operated, and hydrogenation was performed for 120 minutes while controlling the temperature of the titanium raw material to 1000 ° C. or less. The temperature range at this time was 716 degreeC or more and 1000 degrees C or less.
　水素化時におけるチタン原料の嵩密度は１．２ｇ／ｃｍ3であった。 The bulk density of the titanium raw material during hydrogenation was 1.2 g / cm 3 .
　その後、水素化チタンの塊状体は粉砕／分級機で粉砕して粒径が１０μｍ～１５０μｍの水素化チタン粉末を得た。 Thereafter, the block of titanium hydride was pulverized by a pulverizer / classifier to obtain a titanium hydride powder having a particle size of 10 μm to 150 μm.
　真空熱処理炉条件で脱水素処理を行った後、脱水素チタンの塊状体は解砕処理をした。得られたチタン粉のＤ９５粒径は１００μｍであった。 After performing the dehydrogenation process under vacuum heat treatment furnace conditions, the dehydrogenated titanium block was crushed. The obtained titanium powder had a D95 particle size of 100 μm.
　得られたチタン粉の光学顕微鏡写真を図３に示す。チタン粉は樹脂に埋め込み、サンプルの断面を研磨した後、光学顕微鏡で倍率５００倍で、７００μｍ×５００μｍサイズの任意の箇所を１６箇所観察した。ポアの数と面積比を解析した結果、検出したポアは単位面積当たり２０個／ｍｍ2であった。またポア面積比は０．１１％であった。 An optical micrograph of the obtained titanium powder is shown in FIG. The titanium powder was embedded in a resin, and after polishing the cross section of the sample, 16 arbitrary positions of 700 μm × 500 μm size were observed with an optical microscope at a magnification of 500 times. As a result of analyzing the number of pores and the area ratio, the number of detected pores was 20 / mm 2 per unit area. The pore area ratio was 0.11%.
　［実施例２］
　全ＭｇＣｌ2濃度が０．１ｍａｓｓ％以下であるスポンジチタン原料を用いて製造した全ＭｇＣｌ2濃度０．０００２ｍａｓｓ％以下で、その最大厚みが７ｍｍの切粉をチタン原料として用いた。すなわち、該チタン原料の内部ＭｇＣｌ2濃度も０．０００２ｍａｓｓ％以下であった。原料３００ｋｇを５Ｐａ以下に真空引きした後、ヒーターで雰囲気を６５０℃に加熱し、１２０分間保持した。その後、水素を供給して水素吸蔵発熱の反応を起こさせるとともにヒーター制御やＡｒガス挿入および冷却装置を稼働させ、チタン原料が１０００℃以下になるように温度制御しながら１２０分間水素化した。このときの温度範囲は７１６℃以上１０００℃以下であった。 [Example 2]
Total MgCl 2 concentration is less than the total MgCl 2 concentration 0.0002Mass% produced using a titanium sponge material is less than 0.1mass%, the maximum thickness was used chips of 7mm as titanium raw material. That is, the internal MgCl 2 concentration of the titanium raw material was also 0.0002 mass% or less. After evacuating 300 kg of the raw material to 5 Pa or less, the atmosphere was heated to 650 ° C. with a heater and held for 120 minutes. Thereafter, hydrogen was supplied to cause a reaction of hydrogen storage exotherm, and heater control, Ar gas insertion and cooling device were operated, and hydrogenation was performed for 120 minutes while controlling the temperature of the titanium raw material to 1000 ° C. or less. The temperature range at this time was 716 degreeC or more and 1000 degrees C or less.
　水素化時の嵩密度は１．２ｇ／ｃｍ3であった。その後、水素化チタンの塊状体は粉砕／分級機で粉砕して粒径が１０μｍ～１５０μｍの水素化チタン粉末を得た。その後、真空熱処理炉条件で脱水素処理を行った後、脱水素チタンの塊状体は解砕処理した。得られたチタン粉のＤ９５粒径は１００μｍであった。 The bulk density at the time of hydrogenation was 1.2 g / cm 3 . Thereafter, the titanium hydride lump was pulverized by a pulverizer / classifier to obtain a titanium hydride powder having a particle size of 10 μm to 150 μm. Then, after performing a dehydrogenation process in vacuum heat treatment furnace conditions, the lump of dehydrogenated titanium was crushed. The obtained titanium powder had a D95 particle size of 100 μm.
　得られたチタン粉を樹脂に埋め込み、サンプルの断面を研磨した後、光学顕微鏡で倍率５００倍で、７００μｍ×５００μｍサイズの任意の箇所を１６箇所観察した結果、検出したポアは単位面積当たり８個／ｍｍ2であった。またポア面積比は０．０２％であった。 After the obtained titanium powder was embedded in a resin and the cross section of the sample was polished, 16 arbitrary positions of 700 μm × 500 μm size were observed with an optical microscope at a magnification of 500 times. As a result, 8 pores were detected per unit area. / Mm 2 . The pore area ratio was 0.02%.
　なお、上記実施例２では、チタン原料における不純物である鉄濃度が２００質量ｐｐｍ以下、および２００質量ｐｐｍ超５００質量ｐｐｍ以下の２通りでチタン粉を製造した。いずれの場合も検出したポアは単位面積当たり８～１０個／ｍｍ2であった。いずれの場合もポア面積比は０．０２％であった。このため、不純物である鉄量の多少、言い換えればチタン純度は、ポアの挙動と相関はないと考える。 In Example 2 above, titanium powder was produced in two ways: the concentration of iron, which is an impurity in the titanium raw material, being 200 mass ppm or less, and more than 200 mass ppm and 500 mass ppm or less. In all cases, the detected pores were 8 to 10 per mm 2 per unit area. In either case, the pore area ratio was 0.02%. For this reason, the amount of iron, which is an impurity, in other words, titanium purity is considered to have no correlation with pore behavior.
　［実施例３］
　全ＭｇＣｌ2濃度が０．１ｍａｓｓ％以下であるスポンジチタン原料と６０％Ａｌ－４０％Ｖの合金を用いて製造した９０％Ｔｉ－６％Ａｌ－４％Ｖ（質量％）切粉を原料として用いた。原料として用いたチタン合金切粉の全ＭｇＣｌ2濃度は０．０００２ｍａｓｓ％以下で、その最大厚みは７ｍｍであった。すなわち、該チタン合金切粉の内部ＭｇＣｌ2濃度も０．０００２ｍａｓｓ％以下であった。原料３００ｋｇを５Ｐａ以下に真空引きした後、ヒーターで雰囲気を６５０℃に加熱し１２０分間保持した。その後、水素を供給して水素吸蔵発熱の反応を起こさせるとともにヒーター制御やＡｒガス挿入および冷却装置を稼働させ、チタン合金切粉が１０００℃以下になるように温度制御しながら１２０分間水素化した。このときの温度範囲は７１６℃以上１０００℃以下であった。 [Example 3]
90% Ti-6% Al-4% V (mass%) chips produced using a titanium sponge raw material with a total MgCl 2 concentration of 0.1 mass% or less and an alloy of 60% Al-40% V as a raw material Using. The total MgCl 2 concentration of the titanium alloy chips used as the raw material was 0.0002 mass% or less, and the maximum thickness was 7 mm. That is, the internal MgCl 2 concentration of the titanium alloy chips was also 0.0002 mass% or less. After evacuating 300 kg of the raw material to 5 Pa or less, the atmosphere was heated to 650 ° C. with a heater and held for 120 minutes. Thereafter, hydrogen was supplied to cause a reaction of hydrogen occlusion and heat generation, and heater control, Ar gas insertion and cooling device were operated, and hydrogenation was performed for 120 minutes while controlling the temperature of the titanium alloy chips to 1000 ° C. or less. . The temperature range at this time was 716 degreeC or more and 1000 degrees C or less.
　水素化時の嵩密度は１．２ｇ／ｃｍ3であった。その後、水素化チタンの塊状体は粉砕／分級機で粉砕して１０μｍ～１５０μｍの粉末を得た。その後、真空熱処理炉条件で脱水素処理を行い、脱水素チタンの塊状体は解砕処理した。得られたチタン粉のＤ９５粒径は１００μｍであった。 The bulk density at the time of hydrogenation was 1.2 g / cm 3 . Thereafter, the block of titanium hydride was pulverized by a pulverizer / classifier to obtain a powder of 10 μm to 150 μm. Thereafter, dehydrogenation treatment was performed under vacuum heat treatment furnace conditions, and the dehydrogenated titanium mass was crushed. The obtained titanium powder had a D95 particle size of 100 μm.
　得られたチタン合金粉を樹脂に埋め込み、サンプルの断面を研磨した後、光学顕微鏡で倍率５００倍で、７００μｍ×５００μｍサイズの任意の箇所を１６箇所観察した結果、検出したポアは単位面積当たり９個／ｍｍ2であった。またポア面積比は０．０３％であった。 After the obtained titanium alloy powder was embedded in a resin and the cross section of the sample was polished, 16 arbitrary positions of 700 μm × 500 μm size were observed with an optical microscope at a magnification of 500 times. As a result, the detected pore was 9 per unit area. Pieces / mm 2 . The pore area ratio was 0.03%.
　上記で得たチタン合金粉を、高周波熱誘導プラズマ装置にてＡｒガスをプラズマガスとして表面を融解し球状化した。なお、球状化の条件は表１のとおりである。得られたチタン合金粉の光学顕微鏡写真を図４に示す。チタン合金粉は樹脂に埋め込み、サンプルの断面を光学顕微鏡で倍率５００倍として、７００μｍ×５００μｍサイズの任意の箇所を１６箇所観察した。ポアの数と面積比を解析した結果、検出したポアは単位面積当たり３個／ｍｍ2であった。またポア面積比は０．０１％であった。ＨＤＨ法で製造され解砕されたチタン合金粉は、球状粉の原料粉末として有用であることが確認できた。 The titanium alloy powder obtained above was spheroidized by melting the surface with a high-frequency thermal induction plasma apparatus using Ar gas as a plasma gas. The conditions for spheroidization are as shown in Table 1. An optical micrograph of the obtained titanium alloy powder is shown in FIG. The titanium alloy powder was embedded in a resin, and the cross section of the sample was magnified 500 times with an optical microscope, and 16 arbitrary positions of 700 μm × 500 μm size were observed. As a result of analyzing the number of pores and the area ratio, the number of detected pores was 3 / mm 2 per unit area. The pore area ratio was 0.01%. It was confirmed that the titanium alloy powder produced and crushed by the HDH method is useful as a raw material powder for spherical powder.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　［実施例４］
　全ＭｇＣｌ2濃度が０．１ｍａｓｓ％以下であるスポンジチタン原料と７０％Ａｌ－４０％Ｖの合金を用いて製造した８９％Ｔｉ－７％Ａｌ－４％Ｖ（質量％）切粉を原料として用いた。原料として用いたチタン合金切粉の全ＭｇＣｌ2濃度は０．０００２ｍａｓｓ％以下で、その最大厚みは２ｍｍであった。すなわち、該チタン合金切粉の内部ＭｇＣｌ2濃度も０．０００２ｍａｓｓ％以下であった。原料３００ｋｇを５Ｐａ以下に真空引きした後、ヒーターで雰囲気を６５０℃に加熱し１２０分間保持した。その後、水素を供給して水素吸蔵発熱の反応を起こさせるとともにヒーター制御やＡｒガス挿入および冷却装置を稼働させ、チタン合金切粉が１０００℃以下になるように温度制御しながら１２０分間水素化した。このときの温度範囲は７１６℃以上１０００℃以下であった。 [Example 4]
Using as raw material 89% Ti-7% Al-4% V (mass%) chips produced using a sponge titanium material with a total MgCl 2 concentration of 0.1 mass% or less and an alloy of 70% Al-40% V. Using. The total MgCl 2 concentration of the titanium alloy chips used as the raw material was 0.0002 mass% or less, and the maximum thickness was 2 mm. That is, the internal MgCl 2 concentration of the titanium alloy chips was also 0.0002 mass% or less. After evacuating 300 kg of the raw material to 5 Pa or less, the atmosphere was heated to 650 ° C. with a heater and held for 120 minutes. Thereafter, hydrogen was supplied to cause a reaction of hydrogen occlusion and heat generation, and heater control, Ar gas insertion and cooling device were operated, and hydrogenation was performed for 120 minutes while controlling the temperature of the titanium alloy chips to 1000 ° C. or less. . The temperature range at this time was 716 degreeC or more and 1000 degrees C or less.
　水素化時の嵩密度は１．２ｇ／ｃｍ3であった。その後、水素化チタンの塊状体は粉砕／分級機で粉砕して１０μｍ～１５０μｍの粉末を得た。その後、真空熱処理炉条件で脱水素処理を行い、脱水素チタンの塊状体は解砕処理した。得られたチタン粉のＤ９５粒径は１００μｍであった。 The bulk density at the time of hydrogenation was 1.2 g / cm 3 . Thereafter, the block of titanium hydride was pulverized by a pulverizer / classifier to obtain a powder of 10 μm to 150 μm. Thereafter, dehydrogenation treatment was performed under vacuum heat treatment furnace conditions, and the dehydrogenated titanium mass was crushed. The obtained titanium powder had a D95 particle size of 100 μm.
　得られたチタン合金粉を樹脂に埋め込み、サンプルの断面を研磨した後、光学顕微鏡で倍率５００倍で、７００μｍ×５００μｍサイズの任意の箇所を１６箇所観察した結果、検出したポアは単位面積当たり９個／ｍｍ2であった。またポア面積比は０．０３％であった。 After the obtained titanium alloy powder was embedded in a resin and the cross section of the sample was polished, 16 arbitrary positions of 700 μm × 500 μm size were observed with an optical microscope at a magnification of 500 times. As a result, the detected pore was 9 per unit area. Pieces / mm 2 . The pore area ratio was 0.03%.
　実施例２のチタン切粉を用いた結果と比較して、実施例３および実施例４のＴｉ－Ａｌ－Ｖ合金、切粉を用いた結果は同等であった。このため、本実施形態に係るチタン粉の製造方法は、チタン合金粉の製造にも好適であると考える。 Compared to the results using the titanium chips of Example 2, the results using the Ti—Al—V alloy and chips of Examples 3 and 4 were equivalent. For this reason, it considers that the manufacturing method of the titanium powder which concerns on this embodiment is suitable also for manufacture of titanium alloy powder.
　［比較例１］
　チタン原料として内部ＭｇＣｌ2濃度が０．２ｍａｓｓ％のスポンジチタンを用い、その他は、実施例１と同様の条件でチタン粉を製造した。なお、該スポンジチタンの全ＭｇＣｌ2濃度は０．３ｍａｓｓ％であった。得られたチタン粉末を樹脂に埋め込み、サンプルの断面を研磨した後、光学顕微鏡で倍率５００倍として、７００μｍ×５００μｍサイズの任意の箇所を１６箇所観察した。ポアの数と面積比を解析した結果、検出したポアは単位面積当たり８５個／ｍｍ2であった。ポア面積比は、０．７％であった。 [Comparative Example 1]
Titanium powder was produced under the same conditions as in Example 1 except that sponge titanium having an internal MgCl 2 concentration of 0.2 mass% was used as the titanium raw material. The total MgCl 2 concentration of the sponge titanium was 0.3 mass%. The obtained titanium powder was embedded in a resin, and the cross section of the sample was polished. Then, with an optical microscope, the magnification was 500 times, and 16 arbitrary places of 700 μm × 500 μm size were observed. As a result of analyzing the number of pores and the area ratio, the number of detected pores was 85 / mm 2 per unit area. The pore area ratio was 0.7%.
　［比較例２］
　実施例１と同粒径のガスアトマイズ法で製造されたチタン粉末を購入し、樹脂に埋め込み、サンプルの断面を研磨した後、光学顕微鏡で倍率５００倍として、７００μｍ×５００μｍサイズの任意の箇所を１６箇所観察した。ポアの数と面積比を解析した結果、検出したポアは単位面積当たり１３０個／ｍｍ2となった。またポア面積比は、１．０％であった（図５）。 [Comparative Example 2]
Titanium powder produced by the gas atomization method having the same particle size as in Example 1 was purchased, embedded in a resin, and the sample cross section was polished. Then, the magnification was 500 times with an optical microscope, and an arbitrary portion of 700 μm × 500 μm size was obtained. The location was observed. As a result of analyzing the number of pores and the area ratio, the number of detected pores was 130 / mm 2 per unit area. The pore area ratio was 1.0% (FIG. 5).

Claims (6)

  1. 　チタン系粉であって、前記チタン系粉の断面に占めるポアの断面積を前記チタン系粉の断面の面積で除したポア面積比が０．３パーセント以下であることを特徴とするチタン系粉。 A titanium-based powder, wherein the pore area ratio obtained by dividing the cross-sectional area of the pores in the cross-section of the titanium-based powder by the area of the cross-section of the titanium-based powder is 0.3% or less. .
  2. 　前記チタン系粉がＨＤＨ粉である請求項１に記載のチタン系粉。 The titanium-based powder according to claim 1, wherein the titanium-based powder is an HDH powder.
  3. 　チタン系原料に対して、水素化工程、粉砕工程、脱水素工程を含む水素化脱水素法を用いたチタン系粉の製造方法であって、前記チタン系原料に含有される全ＭｇＣｌ2の濃度が１．０ｍａｓｓ％以下であり、内部ＭｇＣｌ2濃度が０．１ｍａｓｓ％以下であることを特徴とするチタン系粉の製造方法。 A titanium-based powder manufacturing method using a hydrodehydrogenation method including a hydrogenation step, a pulverization step, and a dehydrogenation step with respect to a titanium-based material, and the concentration of total MgCl 2 contained in the titanium-based material Is 1.0 mass% or less, and the internal MgCl 2 concentration is 0.1 mass% or less.
  4. 　前記チタン系原料の最大厚みが２０ｍｍ以下であることを特徴とする請求項３に記載のチタン系粉の製造方法。 The method for producing a titanium-based powder according to claim 3, wherein the titanium-based raw material has a maximum thickness of 20 mm or less.
  5. 　前記粉砕工程において、水素化チタン系粉末はＤ９５粒径が３００μｍ以下に粉砕されることを特徴とする請求項３または請求項４に記載のチタン系粉の製造方法。 5. The method for producing a titanium-based powder according to claim 3, wherein in the pulverizing step, the titanium hydride-based powder is pulverized to have a D95 particle size of 300 μm or less.
  6. 　前記水素化工程において、前記チタン系原料の温度を７１６℃以上１０５０℃以下の範囲内で９０分以上の時間をかけて水素化させることを特徴とする請求項３から請求項５のいずれかに記載のチタン系粉の製造方法。 6. The hydrogenation step, wherein the temperature of the titanium-based raw material is hydrogenated over a period of 90 minutes or more within a range of 716 ° C. or more and 1050 ° C. or less. The manufacturing method of the titanium-type powder of description.
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