JP2008183627A - Surface coated tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated tool having high wear resistance and high chipping resistance. <P>SOLUTION: This surface coated tool 1 is obtained by coating the surface of a substrate 2 with a coating layer 3. The coating layer 3 is formed of Ti<SB>1-a-b</SB>Al<SB>a</SB>M<SB>b</SB>(CxN<SB>1-x</SB>) (wherein M is one more kinds selected from elements of fourth group, fifth group and sixth group of the periodic system, rare earth element, and Si, 0.4≤a≤0.65, 0≤b≤0.3, and 0≤x≤1). The coating layer 3 is formed of a structure mainly composed of a columnar crystal 5, and the columnar crystal 5 is formed so that when the Ti content ratio of the whole coating layer 3 is Ti<SB>t</SB>, rich Ti columnar crystal 5a having Ti content ratio of Ti<SB>r</SB>, the ratio Ti<SB>r</SB>/Ti<SB>t</SB>being 1.2-5, is dispersed. Thus, the surface coated tool having high wear resistance and high chipping resistance is formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface-coated tool formed by forming a coating layer on the surface of a substrate.

  Currently, surface-coated tools such as cutting tools, wear-resistant members, and sliding members require wear resistance, slidability, and fracture resistance, so that the surface of a hard substrate such as a WC-based cemented carbide or TiCN-based cermet is used. Various coating layers are formed to improve the wear resistance, slidability, and fracture resistance of surface-coated tools.

  As the coating layer, a TiCN layer or a TiAlN layer is generally widely used, but various coating layers are being developed for the purpose of improving higher wear resistance and fracture resistance.

For example, in Patent Document 1, the crystal grains constituting the TiAlN hard film have a lateral grain diameter of 0.1 to 0.4 μm and an average value of the aspect ratio of the grain diameter of 1.5 to 7 It is described that by using columnar crystals, a tool excellent in oxidation resistance, strength, and cutting characteristics is obtained. Further, Patent Document 2 discloses a film structure in which a multilayer hard film in which two layers of a low-hardness TiAlN film and a high-hardness TiAlN film having different ratios of Ti and Al are sequentially deposited on the surface of a tool base material is disclosed. It is described that the film has excellent adhesion to the base material and is excellent in wear resistance. Patent Document 3 discloses a highly wear-resistant tool in which the ratio of Ti and Al is periodically changed in the thickness direction, and describes that durability against high-speed intermittent cutting is improved. Furthermore, Patent Document 4 describes that in a cutting tool in which a TiAlN layer is formed on the surface of a tool base material, the tool life is prolonged by controlling the Ti / Al ratio to be highest at the edge portion. ing.
Japanese Patent No. 3526392 JP-A-11-61380 JP 7-48666 A JP-A-8-267306

  However, when TiAlN is simply made into columnar crystals as in Patent Document 1, internal stress is generated inside the coating layer. In particular, when the lateral crystal width of the columnar crystals is shortened, the hardness of the coating layer is improved, but the internal stress is increased. However, there was a limit to improving the cutting performance. Further, in the method of changing the ratio of Ti and Al in the thickness direction of the coating layer as in Patent Document 2 and Patent Document 3, as a result of inhibiting the crystal growth in the coating layer and making it difficult for columnar crystals to grow, the coating layer The hardness and toughness were insufficient. Further, in the method of increasing the Ti / Al ratio only for the edge portion of the tool as in Patent Document 4, the hardness of the coating layer decreases when the Ti / Al ratio is increased, so the coating layer at the edge portion has a low hardness. There was a problem that the coating layer was worn early by cutting. Also, in the uniform portion other than the cutting edge of the coating layer, although the hardness is high, the internal stress of the coating layer is also high, and there is a possibility that the coating layer may be partially detached from the substrate or self-destructed. there were.

  Therefore, the surface-coated tool of the present invention is for solving the above-mentioned problems, and an object thereof is to provide a surface-coated tool having high wear resistance and high fracture resistance.

Surface coated tool of the present invention, the surface of the _{substrate, Ti 1-a-b Al} a M b (C x N 1-x) ( however, M is the periodic table Group 4, 5 and 6 elements except Ti, 1 or more selected from rare earth elements and Si, 0.4 ≦ a ≦ 0.65, 0 ≦ b ≦ 0.3, 0 ≦ x ≦ 1)) a is, together with the covering layer is made of tissue mainly composed of columnar crystals extending perpendicularly to the surface of the substrate, the columnar crystals, when the Ti content ratio of the entire coating layer was Ti _t, the ratio Ti _r / Ti _t wealth Ti columnar crystals of Ti content ratio Ti _r to be 1.2 to 5, characterized in that the dispersed.

  Here, in the above configuration, it is desirable that the crystal width of the Ti-rich columnar crystal is three times or more than the average crystal width of the columnar crystal in the coating layer.

  Moreover, in the said structure, it is desirable that the average crystal width of the said columnar crystal is 0.02-0.1 micrometer, and the average crystal width of the said rich Ti columnar crystal is 0.1-1 micrometer.

  Furthermore, in the above configuration, it is desirable that the Ti-rich columnar crystals exist at an average interval of 0.5 to 10 μm.

  In the above configuration, it is desirable that a granular crystal having a grain size larger than the average crystal width of the columnar crystal exists immediately below the Ti-rich columnar crystal.

The surface-coated tool of the present invention has a composition in which the coating layer includes Ti and Al at a specific ratio, and has a columnar crystal that extends perpendicular to the surface of the substrate as a main component, and a structure in which the coating layer is arranged in parallel from the surface of the substrate. becomes, and the Ti content ratio of the columnar crystal is wealth Ti columnar crystals of Ti _r is that a large technical feature are dispersed. As a result, the hardness, toughness and oxidation resistance of the coating layer are improved to have high wear resistance, and the internal stress generated in the coating layer can be reduced to improve the fracture resistance of the tool.

  Here, in the above configuration, when the crystal width of the Ti-rich columnar crystal is three times or more than the average crystal width of the columnar crystal in the coating layer, the effect of reducing internal stress in the coating layer is high. Desirable in terms. In this configuration, the average crystal width of the columnar crystals is 0.02 to 0.1 μm, and the average crystal width of the rich Ti columnar crystals is 0.1 to 1 μm. This is desirable in that the internal stress can be effectively reduced while maintaining the above.

  Further, in the above configuration, the presence of the Ti-rich columnar crystals at an average interval of 0.5 to 10 μm means that the internal stress in the coating layer is maintained while maintaining high wear resistance without locally wearing the coating layer. Is desirable in that it can be effectively reduced.

  Furthermore, in the above configuration, the presence of granular crystals having a grain size larger than the average crystal width of the columnar crystals immediately below the Ti-rich columnar crystals can promote the formation of Ti-rich columnar crystals. This is desirable in that the Ti-rich columnar crystals can be firmly adhered without falling off in the coating layer.

  An example of the surface-coated cutting tool, which is a preferred example of the surface-coated tool of the present invention, will be described based on the schematic perspective view of FIG. 1 and the schematic diagram of the cross-section of the coating layer of FIG.

  A surface-coated cutting tool (hereinafter simply referred to as a tool) 1 shown in FIG. 1 has a shape in which an intersecting ridge line between a rake face 10 and a flank 11 is a cutting edge 12, and a coating layer 3 is formed on the surface of a base 2. The film is formed.

Coating layer _{3, Ti 1-a-b Al} a M b (C x N 1-x) ( however, M is the periodic table Group 4, 5 and 6 elements except Ti, selected from rare earth elements and Si 1 It is a seed or more, and 0.4 ≦ a ≦ 0.65, 0 ≦ b ≦ 0.3, and 0 ≦ x ≦ 1. In the surface-coated tool of the present invention, as shown in FIG. 2, the coating layer 3 has a structure mainly composed of columnar crystals 5 extending perpendicularly to the surface of the substrate 2, and the columnar crystals 5 are composed of coating layers. 3 when the entire Ti content ratio was Ti _t, it is a major feature of rich Ti columnar crystals 5a of the ratio _Ti r / Ti _t is Ti content ratio which is 1.2 to 5 Ti _r are dispersed .

As a result, the hardness, toughness and oxidation resistance of the coating layer 3 are improved to have high wear resistance, and the internal stress generated in the coating layer 3 can be reduced to improve the fracture resistance of the tool 1. it can. Here, when the ratio Ti _r / Ti _{t of the} Ti-rich columnar crystal 5a is less than 1.2, the effect of reducing the internal stress in the coating layer 3 is small, and when the ratio Ti _r / Ti _t is larger than 5, the resistance of the coating layer 3 is increased. Abrasion is reduced. In order to maintain the high hardness of the coating layer 3 while reducing the internal stress of the coating layer 3, it is desirable that the ratio Ti _r / Ti _t is 1.8 to 2.2.

In addition, the content ratio of each element in the columnar crystal can be measured using an energy dispersive X-ray (EDS) analyzer provided in the transmission electron microscope measurement apparatus, and the Ti content ratio in the columnar crystal is It is calculated by the ratio of the total peak intensity of each element and the peak intensity of the Ti element. Here, in the energy dispersive X-ray (EDS) analysis, the Ti Lα ray peak (energy around 0.4 keV) overlaps with the N element Kα ray peak and cannot be measured accurately. In this case, this peak is excluded from the peak used for calculation, and Ti _t and Ti _r are calculated using the peak of Ti Kα line (energy around 4.5 keV), and the ratio Ti _r / Ti _t is obtained. Further, according to the present invention, when measuring Ti _t , the average value is obtained on the basis of measured values at five or more arbitrary positions of the coating layer 3.

  In addition, with the above configuration, residual stress generated in the coating layer 3 can be reduced, and stable film formation is possible without self-destruction even when the coating layer 3 is thickened. Is high and the fracture resistance is improved. Therefore, even if the coating layer 3 is thickened, the coating layer 3 is difficult to chip, and even if the coating layer 3 has a thickness of 0.5 to 6 μm, the coating layer 3 can be prevented from peeling or chipping. Sufficient wear resistance can be maintained.

Note that the composition of the coating layer 3, among the above _{composition, Ti 1-a-b-} c-d Al a M b W c Si d (C x N 1-x) ( however, M is excluding Ti cycle 1 or more types selected from Tables 4, 5, 6 elements, rare earth elements and Si, 0.4 ≦ a ≦ 0.65, 0 ≦ b ≦ 0.3, 0 ≦ x ≦ 1.) In this composition region, the oxidation start temperature is high, the oxidation resistance is high, the wear resistance at the time of cutting is improved, and the chipping that tends to occur at the cutting edge tip can be suppressed, and the fracture resistance is reduced. It will be expensive. Further, the metal M is at least one selected from Nb, Mo, Ta, Hf, and Y. Among them, the inclusion of Nb or Mo is desirable in terms of the most excellent wear resistance and oxidation resistance.

  Furthermore, C and N which are non-metallic components of the coating layer 3 are excellent in hardness and toughness required for the cutting tool, and in order to suppress excessive generation of droplets generated on the surface of the coating layer 3, x A particularly desirable range of (C content ratio) is 0 ≦ x ≦ 0.5. The composition of the coating layer 3 can be measured by energy dispersive X-ray analysis (EDX) or X-ray photoelectron spectroscopy (XPS).

Here, if the crystal width of the rich Ti columnar crystal 5a is three times or more the average crystal width of the columnar crystal 5 in the coating layer 3, the internal stress in the coating layer 3 can be effectively reduced. This is desirable because it can be done. In particular, in order to maintain the hardness of the coating layer 3 while reducing the internal stress in the coating layer 3, the crystal width of the Ti-rich columnar crystal 5 a is 5 with respect to the average crystal width of the columnar crystal 5 in the coating layer 3. It is desirable to be in a range of ˜30 times. In this configuration, the average crystal width of the columnar crystal 5 is 0.02 to 0.1 μm, and the average crystal width of the rich Ti columnar crystal 5a is 0.1 to 1 μm. It is desirable in that the stress can be further effectively reduced and the hardness and oxidation resistance of the coating layer 3 can be maintained. In addition, the crystal width of the columnar crystal 5 in the coating layer 3 is measured by a line A drawn to a portion corresponding to an intermediate thickness of the coating layer 3 forming the columnar crystal 5 as shown in FIG. The average crystal width w _t of the columnar crystals 5 in the coating layer 3 specifies a length L of 100 nm or more of the line A, counts the number of grain boundaries crossing the line A of this length L, and calculates the length L / grain It can be calculated by the number of fields. The crystal width wealth Ti columnar crystals 5a, respectively measured crystal width w _r of the rich Ti columnar crystals 5a in the same position. The columnar crystal in the present invention refers to a crystal whose crystal length in the direction perpendicular to the substrate surface is 1.5 times or more of the crystal width in the direction parallel to the substrate surface.

  In the above configuration, the presence of the Ti-rich columnar crystals 5a at an average interval of 0.5 to 10 μm effectively reduces internal stress in the coating layer 3 while maintaining the high hardness of the coating layer 3. It is desirable in that it can.

  Furthermore, in the above configuration, the presence of the granular crystal 7 having a grain size larger than the average crystal width of the columnar crystal 5 immediately below the Ti-rich columnar crystal 5a promotes the generation of the Ti-rich columnar crystal 5a. This is desirable because the Ti-rich columnar crystals 5a can be firmly adhered without falling off in the coating layer 3.

  Further, the granular crystal 7 is mainly composed of Al, or Ti or M (where M is one or more selected from Group 4, 5, 6 elements of the periodic table excluding Ti, rare earth elements, and Si). ) And having an average particle diameter of 0.05 to 1 μm is desirable from the viewpoint of achieving both the hardness and toughness of the coating layer 3. In particular, the granular crystal 7 includes at least an Al-based granular crystal in which the Al content ratio is higher than the total content ratio of the coating layer, and a Ti / M-based content ratio in which the Ti or M content ratio is higher than the total content ratio of the coating layer 3. It is desirable to include granular crystals. Accordingly, there are granular crystals 7 having different hardness and toughness, and by controlling the dispersion state of these granular crystals 7, the balance of the wear resistance and fracture resistance of the coating layer 3 can be adjusted. In addition, as the element M (where M is one or more selected from Group 4, 5, 6 elements, rare earth elements and Si in the periodic table excluding Ti), W, Nb, Mo, and Si are particularly upward. It is desirable in that the granular crystals 7 having a size that can easily form the Ti-rich columnar crystals 5a are formed.

  Note that the abundance ratio of the granular crystals 7 in the cross-sectional structure observation is 0.1 to 30% by area, so that the fracture resistance of the coating layer 3 can be improved and the wear resistance of the coating layer 3 can be maintained. Is desirable.

  In addition, as the substrate 2, in addition to cemented carbide or cermet composed of tungsten carbide, a hard phase mainly composed of titanium carbonitride, and a binder phase mainly composed of an iron group metal such as cobalt or nickel, silicon nitride And hard materials such as ceramics mainly composed of aluminum oxide, hard phases composed of polycrystalline diamond or cubic boron nitride, and ultra-high-pressure sintered bodies that fire a binder phase such as ceramics or iron group metals under ultra-high pressure. Materials are preferably used.

(Production method)
Next, the manufacturing method of the surface coating cutting tool which is an example of the surface coating tool of this invention is demonstrated.

  First, the tool-shaped substrate 2 is manufactured using a conventionally known method. Next, the coating layer 3 is formed on the surface of the substrate 2. A physical vapor deposition (PVD) method such as an ion plating method or a sputtering method can be suitably applied as a method for forming the coating layer 3. The details of an example of the film forming method will be described. When the coating layer 3 is formed by the ion plating method, metal titanium (Ti), metal aluminum (Al), metal M (where M is a period excluding Ti). 1 or more selected from Tables 4, 5, and 6 elements, rare earth elements and Si) are used for a metal target or a composite alloy target containing each independently.

  At this time, according to the present invention, a film is formed by using a target in which a compound of Ti carbide, nitride, oxide, boride, carbonitride or the like is dispersed together with Ti metal in a metal or alloy target. In addition, a Ti-rich columnar crystal 5 a can be generated in the coating layer 3. Moreover, even if a droplet (granular crystal 7) adheres in the coating layer 3 by adjusting the target so as to contain 0.05 to 0.3% by mass of oxygen, the surface of the granular crystal 7 As a result, the columnar crystal 5 is likely to grow on the granular crystal 7. Although the reason is unknown, the Ti-rich columnar crystal 5a tends to grow on the upper part of the granular crystal 7 of the present invention.

Then, using this target, the metal source is evaporated and ionized by arc discharge or glow discharge, and at the same time, nitrogen (N ₂ ) gas as a nitrogen source or methane (CH ₄ ) / acetylene (C ₂ H ₂ ) as a carbon source. A film is formed by reacting with a gas. At this time, the coating layer 3 is formed by an ion plating method or a sputtering method using a mixed gas of nitrogen (N ₂ ) gas and argon (Ar) gas at a flow rate of argon gas to nitrogen of 1: 9 to 4: 6. Form a film. At this time, each metal element in the target evaporates and adheres to the surface of the substrate 2, but the Ti compound is in a non-uniform evaporation state, and as a result, a Ti-rich columnar crystal is formed in the coating layer 3 formed as a result. 5a is easily generated. Further, Al or M element having a low vapor pressure evaporates as a large spherical mass and adheres directly to the surface of the substrate 2 as a so-called droplet (granular crystal 7). At this time, since the M element has a good familiarity with Ti, the granular crystal containing a large amount of the M element contains a large amount of Ti and contains a large amount of either the M element or Ti, and one of them is the main component. And it becomes easy to grow a Ti-rich granular crystal also on the upper part of the granular crystal 7. FIG. As a result, a structure in which the Ti-rich columnar crystals 5a are dispersed in the formed coating layer 3 is obtained.

  When the coating layer 3 is formed by an ion plating method or a sputtering method, the crystal structure and orientation of the coating layer 3 can be controlled to produce a highly hard coating layer 3 and adhere to the substrate 2. In order to improve the property, it is preferable to apply a bias voltage of 30 to 200V.

10% by mass of metallic cobalt (Co) powder and 1% by mass of vanadium carbide (VC) powder and chromium carbide (Cr ₃ C ₂ ) powder with respect to tungsten carbide (WC) powder having an average particle size of 0.5 μm The mixture was added and mixed at a ratio of, and was formed into an insert shape with a replaceable cutting edge (CNMG0408) and fired. After the grinding process, the surface was washed in the order of alkali, acid, and distilled water to produce an insert substrate.

  Then, the substrate was set in an arc ion plating apparatus equipped with a target shown in Table 1, and the substrate was heated to 550 ° C. to form a coating layer shown in Table 1. The film forming conditions were an arc current of 150 A and a bias voltage of 50 V in a mixed gas of nitrogen gas and argon gas in an atmosphere having a total pressure of 4 Pa.

The obtained insert was observed at a magnification of 500 times using a scanning electron microscope (VE8800) manufactured by Keyence, and energy was used at an acceleration voltage of 15 kV using an EDAX analyzer (AMETEK EDAX-VE9800) attached to the apparatus. The composition of the coating layer was quantitatively analyzed by the ZAF method, which is a type of dispersive X-ray spectroscopy (EDX) method. For elements that could not be measured by this method, a PHI X-ray photoelectron spectrometer (Quantum2000) was used, and the X-ray source was irradiated with monochrome AlK (200 μm, 35 W, 15 kV) to a measurement region of about 200 μm. Measurements were made. The results are shown in Table 1.

Further, the coating layer was observed with a transmission electron microscope (TEM) to confirm the presence or absence of dispersed particles, and the composition of the central portion and the outer peripheral portion of the dispersed particles was quantified by energy dispersive spectroscopy (EDS). . Further, the existence ratio of dispersed particles was calculated for three arbitrary regions of 1 μm × 5 μm. The results are shown in Table 2.

  Next, a cutting test was performed using the obtained insert under the following cutting conditions. The results are shown in Table 3.

Cutting method: Turning work material: SCM450 (4 grooves)
Cutting speed: 150 m / min
Feeding: 0.2mm / rev
Cutting depth: 1.5mm
Cutting condition: Dry evaluation method: Number of impacts until breakage and confirmation of wear / breakage state

From Tables 1 to 3, Sample No. No. in which the film was formed using a target containing no dispersed compound and the Ti-rich columnar crystals were not dispersed. In No. 9, chipping occurred on the cutting edge, leading to a loss early. Also, sample No. consisting of granular crystals. No. 10 had poor wear resistance and a short tool life. Furthermore, the sample No. 1 with a ratio Ti _r / Ti _t smaller than 1.2 and no Ti-rich columnar crystals was present. In No. 11, chipping occurred on the cutting edge, leading to defects early.

On the other hand, the columnar crystal is composed mainly of columnar crystals extending perpendicularly to the surface of the substrate, and the columnar crystals have a ratio Ti _r when the Ti content ratio of the entire coating layer is Ti _t. / sample Ti _t is 1.2 to 5 Ti content ratio are dispersed rich Ti columnar crystals of Ti _r No. In Nos. 1 to 8, the chipping resistance and wear resistance were good and the cutting performance was excellent.

It is a schematic perspective view which shows an example of the surface coating tool of this invention. It is an example of the surface coating tool of this invention, and is a principal part cross-section schematic diagram about a coating layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tool 2 Base | substrate 3 Coating layer 5 Columnar crystal 5a Rich Ti columnar crystal 7 Granular crystal 10 Rake face 11 Flank 12 Cutting edge

Claims (5)

Ti _1-ab Al _a M _b (C _x N _1-x ) (where M is a group selected from Group 4, 5, 6 elements of the periodic table excluding Ti, rare earth elements, and Si) A surface coating tool coated with a coating layer comprising: 0.4 ≦ a ≦ 0.65, 0 ≦ b ≦ 0.3, and 0 ≦ x ≦ 1. together consists tissue which took mainly of columnar crystals extending perpendicularly to the surface of the substrate, the columnar crystals, when the Ti content ratio of the entire coating layer was Ti _t, the ratio Ti r _/ Ti _t is surface-coated tool Ti content ratio to be 1.2 to 5 wealth Ti columnar crystals Ti _r is characterized in that it dispersed. The surface-coated tool according to claim 1, wherein the crystal width of the Ti-rich columnar crystal is three times or more than the average crystal width of the columnar crystal in the coating layer. The surface-coated tool according to claim 2, wherein an average crystal width of the columnar crystals is 0.02 to 0.1 µm, and an average crystal width of the Ti-rich columnar crystals is 0.1 to 1 µm. The surface-coated tool according to any one of claims 1 to 3, wherein the Ti-rich columnar crystals are present at an average interval of 0.5 to 10 µm. The surface-coated tool according to any one of claims 1 to 4, wherein a granular crystal having a grain size larger than an average crystal width of the columnar crystal exists immediately below the rich Ti columnar crystal.

Images