Surface coated cutting tools

Abstract

Provided is a surface-coated cutting tool including a composite carbonitride layer or a composite nitride layer of Ti, Al, and V having columnar crystal grains with an NaCl-type face-centered cubic structure, wherein: the composition thereof is (AlXVYTi1-X-Y)(CαN1-α) (where Xavg, Yavg, and αavg, serving as the average values of X, Y, and α, satisfy the expressions 0.600 ≤ Xavg ≤ 0.950, 0.010 ≤ Yavg ≤ 0.300, 0.610 ≤ Xavg + Yavg ≤ 0.990, and 0.0000 ≤ αavg ≤ 0.0050) and has crystal grains having an Al content variation; Xmax, serving as the average value of the maximum values Xmax* of X, and Xmin, serving as the average value of the minimum values Xmin* of X, in the crystal grains satisfy the expression 0.020 ≤ Xmax - Xmin ≤ 0.400; and the lattice coefficient A (nm), which is calculated from an XRD pattern, and A* (nm), which is A* = 0.4045 × Xavg + 0.4130 × Yavg + 0.4242 × (1-Xavg - Yavg), satisfy |A-A*| < 0.0010 (nm).

Description

Technical Field

[0001] The present invention relates to a surface-coated cutting tool (hereinafter sometimes referred to as a coated tool). This application claims priority based on Japanese Patent Application No. 2022-56505, filed on March 30, 2022. All the descriptions described in the Japanese patent application are incorporated herein by reference.

Background Art

[0002] Conventionally, a coated tool having a coating layer formed on the surface of a substrate such as tungsten carbide (hereinafter referred to as WC)-based cemented carbide is known, and it is known that the coated tool exhibits excellent wear resistance. And various proposals have been made regarding the improvement of the coating layer.

[0003] For example, Patent Document 1 discloses a coated tool including a substrate and a wear-resistant film formed thereon, the wear-resistant film being (Ti x , Al y , V z )(C u , N v , O w )(where x + y + z = 1, u + v + w = 1, 0.2 < x < 1, 0 ≤ y < 0.8, 0.02 ≤ z < 0.6, 0 ≤ u < 0.7, 0.3 < v ≤ 1, and 0 ≤ w < 0.5), and the thickness of the wear-resistant film is 0.5 μm or more and 15 μm or less, and the coated tool is said to have improved wear resistance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in consideration of the above circumstances and proposals, and an object of the present invention is to provide a coated tool that has excellent fracture resistance, thermal crack resistance, and wear resistance even in, for example, high-speed intermittent cutting. [Means for solving the problem]

[0006] The surface-coated cutting tool according to an embodiment of the present invention comprises: A substrate and a coating layer on the surface of the substrate are included. (a) The coating layer is a composite nitride of Ti, Al and V having columnar crystal grains with a face-centered cubic structure of NaCl type. of Layer or composite carbonitride of layer, (b) The composite nitride or composite carbonitride is (Al X V Y Ti 1-X-Y )(C α N 1-α )(X, Y, α, the mean value of X avg , Y avg , α avg are 0.600≦X avg ≦0.950, 0.010≦Y avg ≦0.300, 0.610≦X avg +Y avg ≦0.990, 0.0000≦α avg ≦0.0050), (c) the composite nitride of Layer or composite carbonitride of The layer has crystal grains with a varying Al content, and the maximum value X of X in the crystal grains max * is the average value of X max and the minimum value X of X min * is the average value of X min However, 0.020≦X max -X min Satisfies ≦0.400, (d)A * =0.4045×X avg +0.4130×Y avg +0.4242×(1-X avg -Y avg ) is A *(nm) and the lattice constant A (nm) calculated from the XRD pattern. |AA * Meets the requirement of |<0.0010(nm).

[0007] Furthermore, the surface-coated cutting tool according to the above embodiment may satisfy the following (1).

[0008] (1) The composite nitride of Layer or composite carbonitride of The layer has the Al content change and The aforementioned The maximum value Y of Y in the crystal grains has a change in the content of V. max * is the average value of Y max and the minimum value Y of Y min * is the average value of Y min However, 0.010≦Y max -Y min Must satisfy ≦0.200. [Effects of the Invention]

[0009] The surface-coated tools have improved chipping resistance, thermal cracking resistance and wear resistance. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic view showing an example of a vertical cross section of a surface-coated cutting tool according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic perspective view of a portion of a gas supply pipe of an example of an apparatus for manufacturing a surface-coated cutting tool according to the present embodiment. [Figure 3] FIG. 3 is a cross-sectional view of the gas supply pipe of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present inventors have conducted extensive research into improving the thermal crack resistance and wear resistance of a composite nitride layer or composite carbonitride layer of Al, V, and Ti (hereinafter, sometimes referred to as "(AlVTi)CN") in high-speed interrupted cutting, for example, at a cutting speed of 300 m / min or more using an insert. As a result, they have found that sufficient chipping resistance, thermal cracking resistance, and wear resistance cannot be obtained by simply coating with an (AlVTi)CN layer, but that the chipping resistance, thermal cracking resistance, and wear resistance of the layer are improved when a certain relationship is established between the lattice constant calculated from the composition according to Vegard's law and the lattice constant determined by XRD.

[0012] We also found that when crystal grains with varying Al content (composition) exist and the difference between the maximum and minimum values ​​satisfies a specified range, thermal crack resistance and chipping resistance are improved, and further, when the V content (composition) also changes in crystal grains with varying Al content (composition) and the difference between the maximum and minimum contents satisfies a specified range, thermal crack resistance and chipping resistance are further improved.

[0013] A surface-coated cutting tool according to an embodiment of the present invention will be described below. In this specification and claims, when a numerical range is expressed as "L to M" (where L and M are both numerical values), this is synonymous with "not less than L and not more than M," and the range includes an upper limit (M) and a lower limit (L). When a unit is stated only for the upper limit, the upper limit (M) and the lower limit (L) have the same unit.

[0014] 1.Coating layer As shown in FIG. 1, the coating layer (2) provided on the substrate (1) is made of (Al VTi In addition to the CN layer (3), the substrate (4) and upper layer (5) may be provided, but these layers (4) and (5) are not essential.

[0015] 1-1.(Al VTi )CN layer The (AlVTi)CN layer that is always included in the coating layer will now be described.

[0016] (1) Average thickness In this embodiment, it is preferable to have an (AlVTi)CN layer with an average thickness of 1.0 to 20.0 μm. The reason for setting the average thickness of the (AlVTi)CN layer within this range is that if the average thickness is less than 1.0 μm, the thermal crack resistance and wear resistance provided by this layer cannot be exhibited, while if it exceeds 20.0 μm, chipping resistance decreases. The average thickness is more preferably 3.0 to 15.0 μm.

[0017] (2) Grain shape The (AlVTi)CN layer preferably has columnar crystal grains with a NaCl-type face-centered cubic structure in a longitudinal section, as described below. Here, columnar crystal grains refer to crystal grains with an aspect ratio of 1.5 or more. This is because columnar crystal grains have fewer grain boundaries parallel to the substrate, which can suppress chipping originating from these grain boundaries. The columnar crystal grains of NaCl type face-centered cubic structure with an aspect ratio of 1.5 or more preferably account for 50% or more of the area in the vertical cross section. If they account for 50% or more of the area (or even 100% of the area), chipping can be suppressed.

[0018] The aspect ratio is more preferably 2.0 or more, and the area ratio of columnar crystal grains of NaCl type face-centered cubic structure having an aspect ratio of 2.0 or more is more preferably 70 area % or more in the vertical cross section.

[0019] The reason is that if the area ratio is 70% or more (100% by area, i.e., all crystal grains may be crystal grains having a columnar structure with an aspect ratio of 2.0 or more), the occurrence of chipping can be further suppressed.

[0020] Here, the longitudinal section of the insert is the cross section of the substrate when the surface of the substrate is considered to be flat, with no irregularities on the surface. Surface In the case of an axial tool, it is a cross section perpendicular to the axis.

[0021] Although there is no upper limit to the aspect ratio, the upper limit is preferably 10.0. This is because if the aspect ratio exceeds 10.0, the columnar crystal structure becomes more susceptible to fracture, which can cause significant chipping. The method for calculating the aspect ratio will be described later.

[0022] (3) Composition (3-1) Average composition The (AlVTi)CN layer has the formula: (Al X V Y Ti 1-X-Y )(C α N 1-α ) X, Y, α is the average value of avg , Y avg , α avg are 0.600≦X avg ≦0.950, 0.010≦Y avg ≦0.300, 0.610≦X avg +Y avg ≦0.990, 0.0000≦α avg It is preferred that it is ≦0.0050.

[0023] X avg The reason for specifying the content of X in the above range is that avg If the ratio is less than 0.600, the hardness of the (AlVTi)CN layer is insufficient and the wear resistance is reduced, while if the ratio exceeds 0.950, the hexagonal structure of wurtzite in the layer is likely to form, which can cause abnormal damage such as uneven wear.

[0024] Y avg The reason for setting the content of Y in the above range is that avg If it is less than 0.010, the improvement in the lubricity of the (AlVTi)CN layer is insufficient, while if it exceeds 0.300, the hardness of the layer becomes insufficient, resulting in a decrease in wear resistance.

[0025] X avg +Y avg The reason for specifying the content range is that the lower limit is X avg and Y avgOn the other hand, if it exceeds 0.990, the hardness of the (AlVTi)CN layer becomes insufficient, and the wear resistance decreases.

[0026] X avg , Y avg , and X avg +Y avg are respectively 0.760≦X avg ≦0.900, 0.020≦Y avg ≦0.050, 0.780≦X avg +Y avg It is more preferred that it is ≦0.950.

[0027] α avg The reason why the content of α is set to the above range is that when it is within this range, the wear resistance of the (AlVTi)CN layer is improved, while when it is outside this range, abnormal damage such as uneven wear occurs. avg is 0.0020≦α avg ≦0.0035 is more preferred.

[0028] Cl is inevitably contained during the manufacturing process. The ratio Z of the number of Cl atoms to the total number of Al, Ti, V, C, N, and Cl atoms is more preferably 0.005 atomic % or more and 0.500 atomic % or less. The reason is that if Z is less than 0.005 atomic percent, the lubricity of the (AlVTi)CN layer becomes insufficient, resulting in reduced wear resistance, while if it exceeds 0.500 atomic percent, the hardness decreases, resulting in insufficient wear resistance of the rake face of the layer, leading to early wear. It is even more preferable that Z is 0.005 atomic percent or more and 0.100 atomic percent or less.

[0029] (3-2) Content Change There are crystal grains having a predetermined change in the content (composition) of Al within the grains, and the maximum value X of the Al content X in the crystal grains max * is the average value of X max and the minimum value X of X min * is the average value of X min However, 0.020≦X max -X minIt is preferable to satisfy the condition of ≦0.400 in order to further improve the thermal crack resistance and chipping resistance. Furthermore, when the crystal grains having the Al content change have the V content change, the V content Y in the crystal grains is the maximum value Y max * is the average value of Y max and the minimum value Y of Y min * is the average value of Y min However, 0.010≦Y max -Y min If the range of 0.200 or less is satisfied, the thermal cracking resistance and chipping resistance of the coated tool are further improved. Here, the subscript "*" indicates that the value is determined for each crystal grain.

[0030] The proportion of crystal grains having a change in the Al content alone or in the contents of both Al and V within the grains is 50% by area or more, more preferably 70% by area or more (it may be 100% by area) in the longitudinal section, because if it is less than 70% by area, the thermal cracking resistance and chipping resistance of the coated tool may be reduced when subjected to high-speed interrupted cutting.

[0031] (3-3)(Al X V Y Ti 1-X-Y ) and (C α N 1-α ) (Al X V Y Ti 1-X-Y ) and (C α N 1-α The ratio of Al to Al is not particularly limited. X V Y Ti 1-X-Y ) is set to 1, (C α N 1-α The ratio of (Al) is preferably 0.8 to 1.2. X V Y Ti 1-X-Y ) to (C α N 1-α ) within the above range, the above-mentioned object can be more reliably achieved.

[0032] (3-4)NaCl type face-centered cubic structure The (AlVTi)CN layer preferably contains crystal grains having a NaCl-type face-centered cubic structure. That is, in the longitudinal section, the proportion of crystal grains having a NaCl-type face-centered cubic structure is preferably 50% or more by area, more preferably 70% or more by area. All crystal grains (100% by area) may have a NaCl-type face-centered cubic structure.

[0033] (4) Difference in lattice constants The lattice constant (A) obtained from the composition of the (AlVTi)CN layer * It is preferable that the difference between the lattice constant (A (nm)) obtained by XRD and the lattice constant (A (nm)) is a predetermined value. |AA * It is preferable that |<0.0010 (nm). The reason is that if it is 0.0010 or more, the number of crystal grains having a crystal structure other than the NaCl-type face-centered cubic structure increases, and the wear resistance of the (AlVTi)CN layer decreases.

[0034] where: A * is calculated from the following formula according to Vegard's law: A * =0.4045×X+0.4130×Y+0.4242×(1-XY).

[0035] In contrast, A is calculated by powder X-ray diffraction measurement in a state where the influence of residual stress has been eliminated (after removing as much of the substrate as possible from the (AlVTi)CN layer by polishing, etching, etc., and then pulverizing the (AlVTi)CN layer), and calculating the values ​​of the lattice spacings d(111) and d(200) from the diffraction angles of the 111 diffraction line and the 200 diffraction line in the obtained X-ray diffraction pattern, and calculating A(111) or A(200) defined as A(111) = √3d(111) and A(200) = 2d(200), and then calculating the average of these.

[0036] Here, the X-ray diffraction pattern is determined, for example, as follows. The X-ray diffraction device used was a Spectris PANalytical Empyrean, and measurements were performed using the 2θ-θ method with CuKα radiation. The measurement conditions were: measurement range (2θ): 15 to 135 degrees, X-ray output: 45 kV, 40 mA, divergence slit: 0.5 degrees, scan step: 0.013 degrees, and measurement time per step: 0.16 sec / step. The diffraction angle is calculated by the WPPD method (Whole-powder-pattern Decomposition method: see, for example, Bulletin of the Japan Institute of Metals, Vol. 28, No. 3 (1989), p. 189).

[0037] 1-2.Other layers The (AlVTi)CN layer of this embodiment is sufficient to achieve the above-mentioned object by itself, but an underlayer and / or an upper layer may also be provided.

[0038] (1) Base layer The underlayer is composed of one or more Ti compound layers selected from the group consisting of Ti carbide, nitride, carbonate, and carbonitride layers (the composition of these Ti compound layers is not limited to the stoichiometric composition), and has a total average layer thickness of 0.1 to 20.0 μm. The underlayer improves adhesion between the (AlVTi)CN layer and the substrate.

[0039] (2) Upper layer The upper layer has a total average thickness of 0.1 to 25.0 μm including the aluminum oxide (not limited to a stoichiometric composition) layer, and improves wear resistance.

[0040] (3) Unintended demographic In this embodiment, no layers other than the underlayer, (AlVTi)CN layer, and upper layer are intentionally deposited. However, due to unpredictable changes in the furnace pressure and temperature when switching deposition gases, there is a possibility that unintended layers other than these layers may be deposited.

[0041] 2.Base (1)Material Any conventionally known substrate material can be used as long as it does not impede the achievement of the object of the present invention. For example, WC-based cemented carbide (containing Co in addition to WC and also containing carbonitrides of Ti, Ta, Nb, etc.), cermet (containing TiC, TiN, TiCN, etc. as its main component), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide), or cBN sintered body is preferred.

[0042] (2) Shape The shape of the substrate is not particularly limited as long as it is a shape that can be used as a cutting tool, and examples thereof include the shape of an insert and the shape of a drill.

[0043] 3. Manufacturing method The (AlVTi)CN layer of this embodiment can be manufactured by CVD using, for example, a gas group A containing NH3, Ar, and H2, and a gas group B containing TiCl4, VCl4, AlCl3, Ar, N2, C2H4, and H2.

[0044] Here, gas groups A and B are supplied separately into the space inside the reaction chamber of the thermal CVD apparatus up to just before the object to be film-formed (substrate). Then, gas groups A and B are mixed and reacted just before the object to be film-formed in the reaction chamber. This is an effective method for uniformly forming a film across the film-forming region using gas species that are highly reactive with each other, and detailed technical details are disclosed, for example, in Japanese Patent Publication No. 6358420.

[0045] The film forming apparatus described in the publication has a gas supply pipe as shown in FIGS. 2 and 3, and its structure will be described below. As shown in Figures 2 and 3, the gas supply pipe (6), which is a cylindrical pipe that rotates around its center at a predetermined rotational speed, has its interior divided into approximately two equal parts by a partition member extending along its axial direction, and has a gas group A flow section (9) and a gas group B flow section (10).

[0046] As shown in FIG. 2, the gas supply pipe (6) is provided with a plurality of gas group A outlets (7) and gas group B outlets (8) along the axial direction, which constitute an outlet pair at approximately the same height.

[0047] The gas group A nozzle (7) and the gas group B nozzle (8) shown in FIG. 3 belong to the same nozzle pair, and the center (11) of the outer peripheral opening end of the gas group A nozzle (7) and the center (12) of the outer peripheral opening end of the gas group B nozzle (8) are aligned. Distance from center (12) The angle (14) is set to a predetermined value. Also, the angle (15) formed by the center (11) of the outer peripheral opening end of the gas group A nozzle (7), the center (13) of the rotation axis of the gas supply pipe, and the center (12) of the outer peripheral opening end of the gas group B nozzle (8) projected onto a plane perpendicular to the rotation axis is set to a predetermined value.

[0048] 4.Measurement method The method for measuring each value in this embodiment will be described below. In this specification, the term "longitudinal cross section" refers to a cross section perpendicular to the surface of the substrate when the substrate surface is treated as a flat surface, ignoring minute irregularities on the surface of the substrate. Furthermore, in this specification, the surface of the substrate refers to the average line (straight line) of the interface roughness between the substrate and the coating layer in an observed image of the longitudinal cross section. The direction perpendicular to this average line is defined as the direction perpendicular to the substrate (thickness direction of the coating layer). Even when the base has a curved surface, such as a drill, the surface of the base can be determined in a similar manner. The longitudinal section is prepared by polishing the coating layer using a focused ion beam system (FIB), a cross section polisher (CP), or the like.

[0049] (1) Average thickness A vertical section (when the coated tool is an insert, a vertical section including the flank is preferable) is observed with a scanning electron microscope, with a rectangular measurement area being 100 μm in the horizontal direction (direction parallel to the substrate surface) and allowing the entire thickness of the coating layer to be observed in the vertical direction (thickness direction of the coating layer). The average value of the thicknesses measured at multiple locations (e.g., five locations) is taken as the average thickness.

[0050] (2) The area ratio of crystal grains with NaCl-type face-centered cubic structure and columnar crystal grains with aspect ratios of 1.5 and 2.0 or more In the measurement region of the longitudinal section, an electron backscatter diffraction (EBSD) analyzer is used to analyze, for example, (Al VTi A measurement area that includes the entire thickness of the CN layer and contains 20 or more crystal grains to be measured is irradiated with an electron beam at an incident angle of 70 degrees, an accelerating voltage of 15 kV, and an irradiation current of 1 nA at intervals of 0.01 μm. The crystal structure is analyzed based on the electron beam backscatter diffraction image obtained by irradiating the area with an electron beam at an incident angle of 70 degrees, an accelerating voltage of 15 kV, and an irradiation current of 1 nA at intervals of 0.01 μm. The boundaries between areas with different crystal structures are then defined, and the crystal grains are identified. The area of ​​crystal grains determined to have a NaCl-type face-centered cubic structure by the analysis of this crystal structure ratio Ask for.

[0051] Then, the crystal grains that were judged to have an NaCl-type face-centered cubic structure i Image processing is performed on the crystal grain i, and the maximum length Hi of the crystal grain i in the direction perpendicular to the surface of the substrate (when the surface of the substrate is treated as a flat surface, the direction perpendicular to this surface) is calculated. Substrate surface The grain width Wi, which is the maximum length in the horizontal direction (the direction parallel to the surface when the substrate surface is treated as a flat plane), and the area Si of crystal grain i are calculated. The aspect ratio Ai of crystal grain i is calculated as Ai = Hi / Wi. Then, the aspect ratio A is calculated according to [Equation 1] (n in [Equation 1] is 20 or more).

[0052]

number

[0053] (3) Values ​​of X, Y, and α X and Y, which define the composition of the (AlVTi)CN layer, can be determined, for example, by using an electron probe microanalyzer (EPMA) to irradiate a polished longitudinal cross-section of the (AlVTi)CN layer with an electron beam (beam diameter 1 μm) onto the surface of the longitudinal cross-section and averaging the resulting characteristic X-ray analysis results at 10 points. Alternatively, energy dispersive X-ray spectroscopy (EDS) can be used to irradiate the polished longitudinal cross-section of the (AlVTi)CN layer with an electron beam from the longitudinal cross-section and perform multiple line analyses (e.g., five lines) in the thickness direction of the (AlVTi)CN layer to obtain average values ​​based on the compositional analysis results of Al, Ti, and V.

[0054] In addition, α is determined by secondary ion mass spectrometry (SIMS). Specifically, the content in the depth direction of the (AlVTi)CN layer is measured by alternately repeating surface analysis using an ion beam and etching using a sputtered ion beam. Specifically, the average C and N content values ​​measured at a depth of at least 1 μm from the surface of the (AlVTi)CN coating layer at a pitch of 0.1 μm or less in the thickness direction are calculated, and the average C / (C+N) value calculated from this measurement is taken as the C content.

[0055] In addition, the maximum value X of the Al content X in the crystal grains having a change in the content of only Al or both Al and V within the grains max * is the average value of X max and the minimum value X of X min * is the average value of X min , the maximum value of V content Y max * is the average value of Y max and the minimum value Y of Y min * is the average value of Y min Furthermore, the area ratio of the crystal grains having predetermined changes in the content of Al and V in the (AlVTi)CN layer can be calculated, for example, as follows.

[0056] Using an energy dispersive X-ray spectrometer attached to a scanning transmission electron microscope (STEM), the longitudinal section of the (AlVTi)CN layer is observed at an appropriate magnification ranging from 160,000 to 320,000 times.

[0057] Then, a rectangular observation field is set in the longitudinal section of the (AlVTi)CN layer so that its longitudinal length includes the entire thickness of the AlVTi)CN layer and its lateral length is 2 μm or more in the direction parallel to the surface of the substrate. Over the entire observation field, the Al content (X) in the total amount of V, Ti, and Al and the V content (Y) in the total amount of V, Ti, and Al are determined.

[0058] For each crystal grain (not limited to those with a NaCl-type face-centered cubic structure) included in the entire observation field, the distribution of the Al content (X) in the total amount of V, Ti, and Al, and the V content (Y) in the total amount of V, Ti, and Al is calculated, and the maximum value X max * and Min X min * and maximum Y max * and minimum Y min *The average value of both X and Y (X avg * or Y avg *) is determined to contain a change in the Al content (composition) alone, or in the Al and V content (composition).

[0059] That is, a crystal grain having a change in the content of only Al or both Al and V within the grain refers to a region that includes (totals) crystal grains that are determined to have a change in the content of only Al or both Al and V. The maximum value X measured in each crystal grain max *, minimum X min *The average value of each is the maximum value X max , minimum X min , maximum Y max *, minimum Y min *The average value of each of the maximum Y max , minimum Y min Let's say.

[0060] The average value of X in the region including the change in Al content (X avg It is more preferable that the regions (high Al content regions) with a difference of +1% or more from the value of *) and the regions (low Al content regions) with a difference of -1% or more are distributed in a mesh, layer, or granular pattern. Furthermore, it is even more preferable that the minimum distance between the outer edges of high Al content regions separated by low Al content regions, or between the outer edges of low Al content regions separated by high Al content regions, is 1 nm or more and less than 50 nm.

[0061] The reason is that when the minimum value of the interval of change in Al content is within this range, the thermal cracking resistance and chipping resistance of the coated tool are improved, but if it is less than 1 nm, the improvement in thermal cracking resistance may not be sufficient, and if it is 50 nm or more, the improvement in chipping resistance may not be sufficient.

[0062] In the observation field, the proportion of the total area of ​​crystal grains having a predetermined change in the Al content only within the grains, and the proportion of the total area of ​​crystal grains having a predetermined change in the Al and V contents within the grains are defined as the proportion of the area of ​​crystal grains having a predetermined change in the Al content only within the (AlVTi)CN layer and the proportion of the area of ​​crystal grains having a predetermined change in the Al and V contents within the grains, respectively.

[0063] Furthermore, even if the (AlVTi)CN layer contains a small amount of unavoidable impurities (impurities that are unintentionally included) such as oxygen, this does not hinder the achievement of the above-mentioned purpose.

[0064] (4) Z value The Cl content in the (AlVTi)CN layer is determined, for example, by using an EPMA to irradiate an electron beam on a polished vertical cross section of a sample, and then determining the chlorine content from the analysis results of the characteristic X-rays obtained.

[0065] The above description includes the following additional features. (Appendix 1) A surface-coated cutting tool having a substrate and a coating layer on a surface of the substrate, (a) The coating layer is a composite nitride of Ti, Al and V having columnar crystal grains with a face-centered cubic structure of NaCl type. of Layer or composite carbonitride of layer, (b) The composite nitride or composite carbonitride is (Al X V Y Ti 1-X-Y )(C α N 1-α )(X, Y, α, the mean value of X avg , Y avg , α avg are 0.600≦X avg ≦0.950, 0.010≦Y avg ≦0.300, 0.610≦X avg +Y avg ≦0.990, 0.0000≦α avg ≦0.0050), (c) the composite nitride of Layer or composite carbonitride of The layer has crystal grains with a varying Al content, and the maximum value X of X in the crystal grains max * is the average value of X max and the minimum value X of X min * is the average value of X min However, 0.020≦X max -X min Satisfies ≦0.400, (d)A * =0.4045×X avg +0.4130×Y avg +0.4242×(1-X avg -Y avg ) is A * (nm) and the lattice constant A (nm) calculated from the XRD pattern. |AA * |<0.0010 (nm) Satisfy A surface-coated cutting tool characterized by: (Appendix 2) The composite nitride of Layer or composite carbonitride of The layer has the Al content change and The aforementionedThe maximum value Y of Y in the crystal grains has a change in the content of V. max * is the average value of Y max and the minimum value Y of Y min * is the average value of Y min However, 0.010≦Y max -Y min 2. The surface-coated cutting tool according to claim 1, wherein the surface-coated cutting tool satisfies ≦0.200. (Appendix 3) 2. The surface-coated cutting tool according to claim 1, wherein the crystal grains having a varying Al content occupy 50% by area or more and 100% by area or less in a longitudinal section. (Appendix 4) 4. The surface-coated cutting tool according to any one of Appendices 1 to 3, wherein, in the crystal grains having a varying Al content, a minimum value of a distance between outer edges of high Al content regions separated by low Al content regions, or between outer edges of low Al content regions separated by high Al content regions, is 1 nm or more and less than 50 nm. (Appendix 5) The change in the Al content and The aforementioned 3. The surface-coated cutting tool according to claim 2, wherein crystal grains having both a change in V content and a change in V content account for 50% by area or more and 100% by area or less in a longitudinal section. (Appendix 6) 6. The surface-coated cutting tool according to any one of claims 1 to 5, wherein the columnar crystal grains of the NaCl type face-centered cubic structure account for 50% or more by area in a longitudinal section. (Appendix 7) 7. The surface-coated cutting tool according to any one of claims 1 to 6, wherein the columnar crystal grains of the NaCl type face-centered cubic structure have an aspect ratio of 1.5 or more. (Appendix 8) 8. The surface-coated cutting tool according to any one of Appendix 1 to Appendix 7, wherein a ratio Z of the number of Cl atoms to the total number of Al, Ti, V, C, N, and Cl atoms is 0.005 atomic % or more and 0.500 atomic % or less. [Example]

[0066] The present invention will be described below with reference to examples, but is not limited to these examples. That is, an insert cutting tool using a WC-based cemented carbide as the substrate material will be described, but the substrate material may be any of the above-mentioned materials, and the shape of the substrate may be that of a drill or the like, as described above.

[0067] 1. Manufacturing of the substrate WC powder, TiC powder, TaC powder, NbC powder, Cr3C2 powder, and Co powder were prepared as raw material powders. These raw material powders were blended according to the composition shown in Table 1, and wax was added. The mixture was ball milled in acetone for 24 hours, dried under reduced pressure, and then pressed into a green compact of the desired shape at a pressure of 98 MPa.

[0068] This compact was then vacuum sintered under conditions of 5 Pa vacuum and 1420°C for 1 hour, and after sintering, WC-based cemented carbide substrates a to c with insert shapes of SEMT13T3AGSN-JM manufactured by Mitsubishi Materials Corporation, with the cutting edge honed to R: 0.06 mm, and WC-based cemented carbide substrates d to f with insert shapes of CNMG120408-MA manufactured by Mitsubishi Materials Corporation, with the cutting edge honed to R: 0.05 mm, were produced.

[0069] 2. Film formation An (AlVTi)CN layer was formed on the surface of each of the substrates a to f using a CVD apparatus to obtain Examples 1 to 11 shown in Table 5. The film formation conditions were as shown in Table 2, and were roughly as follows:

[0070] Reaction gas composition (the content (%) of gas components is expressed as volume % when the total of Gas Group A and Gas Group B is 100 volume %): Gas Group A: TiCl4:0.01~0.30%, AlCl3:0.30~1.60%, VCl4:0.05~0.70%, Ar:5.0~10.0%, N2:0.0~10.0%, C2H4:0.0~0.5%, H2:Remaining Gas Group B: NH3:1.00~3.50%, N2:0.0~12.0%, H2:30.0~50.0% Reaction atmosphere pressure: 4.0 to 5.0 kPa Reaction atmosphere temperature: 700-900℃

[0071] Here, gas group A and gas group B were supplied as source gas A and source gas B, respectively, to the CVD apparatus described in the aforementioned Japanese Patent No. 6358420. The rotation speed of the gas supply pipe, the distance (14) between the center (11) of the outer peripheral opening end of the gas group A nozzle (7) of the gas supply pipe and the center (12) of the outer peripheral opening end of the gas group B nozzle (8), and the angle (15) formed by the center (11) of the outer peripheral opening end of the gas group A nozzle (7), the center (13) of the rotation axis of the gas supply pipe, and the center (12) of the outer peripheral opening end of the gas group B nozzle (8) projected onto a plane perpendicular to the rotation axis are as follows:

[0072] Gas supply pipe rotation speed: 30 rpm Distance(14):6mm Angle (15): 16 degrees

[0073] In Examples 1 to 11, as shown in Table 4 under the conditions shown in Table 3, only the underlayer or both the underlayer and the upper layer were deposited in some of the examples.

[0074] For comparison, (AlVTi)CN layers were formed on the surfaces of substrates a to f under the film formation conditions shown in Table 2, and Comparative Examples 1 to 10 shown in Table 5 were obtained.

[0075] In the example, gas group A and gas group B were supplied separately in the space inside the reaction vessel of the thermal CVD apparatus up to just before the film formation target, where they mixed and reacted. However, in the comparative example, the source gas was not separated into two systems but was supplied into the reaction vessel of the thermal CVD apparatus from a single gas supply pipe. 7 ) and gas group B nozzle ( 8 ) and a gas supply pipe without a nozzle pair was used.

[0076] In Comparative Examples 1 to 10, as shown in Table 4 under the conditions shown in Table 3, only the underlayer or both the underlayer and the upper layer were formed in some of the comparative examples.

[0077] [Table 1]

[0078] [Table 2]

[0079] [Table 3]

[0080] [Table 4]

[0081] In Table 4, "-" indicates that there is no corresponding layer, and type 1 indicates that there is neither a base layer nor an upper layer.

[0082] [Table 5]

[0083] In Table 5, Y avg is less than 0.001, α avg is less than 0.0001 atomic percent, and Z is less than 0.001 atomic percent, which are below the analytical limit. avg and Z is 0.000, α avg can be regarded as 0.0000. Also, Y max -Y min The "-" in Y avg is less than 0.001, V element is below the detection limit, and Y max -Y min This indicates that it is not possible to calculate (there is no change in content).

[0084] In addition, "existence in a mesh, layer, or granular form" means "the average value of X (X avg *) (high Al content regions) with a difference of +1% or more and regions (low Al content regions) with a difference of -1% or more are distributed in a mesh, layer, or granular pattern. A "○" indicates that the region is distributed, and a "-" indicates that the region is not distributed. The "minimum distance between the outer edges of each region" refers to the "minimum distance between the outer edges of high Al content regions separated by low Al content regions, or the minimum distance between the outer edges of low Al content regions separated by high Al content regions."

[0085] Next, for Examples 1 to 11 and Comparative Examples 1 to 10, the following cutting tests 1 and 2 were carried out with each sample clamped to the tip of a tool steel cutter with a cutter diameter of 125 mm using a fixing jig, and the flank wear width of the cutting edge was measured.

[0086] Cutting test 1: Dry high-speed face milling, center cut cutting Cutter diameter: 125mm Workpiece: JIS S55C block material, width 100mm, length 400mm Rotation speed: 891 / min Cutting speed: 350m / min Cutting depth: 2.0mm Feed per tooth: 0.2mm / tooth Cutting time: 20.2 minutes (Normal cutting speed is 150-250m / min)

[0087] Cutting test 2: Dry high-speed interrupted cutting Workpiece: JIS S55C round bar with four longitudinal grooves spaced equally apart along the length Cutting speed: 300m / min Cutting depth: 2.0mm Feed: 0.2mm / rev Cutting time: 10 minutes (Normal cutting speed is 150-200m / min)

[0088] Tables 6 and 7 show the results of Cutting Test 1 and Cutting Test 2, respectively. Note that for Comparative Examples 1 to 10, chipping occurred before the end of the cutting time, causing the tool to reach the end of its life. Therefore, the flank wear width (mm) was used instead of the flank wear width (mm). cutting Indicates the time (minutes).

[0089] [Table 6]

[0090] [Table 7]

[0091] As is clear from the results shown in Tables 6 and 7, none of the examples produced chipping, had improved fracture resistance, and exhibited excellent cutting performance over a long period of time. In contrast to this, in all of Comparative Examples 1 to 10, chipping occurred before the end of the cutting time, and the usable life was reached in a short period of time.

[0092] The above-disclosed embodiments are merely illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, not by the above-disclosed embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims. [Explanation of symbols]

[0093] 1 Base 2 Covering layer 3 (AlVTi)CN layer 4 Base layer 5 Upper layer 6 Gas supply pipe 7 Gas group A nozzle 8 Gas group B nozzle 9 Gas Group A Distribution Section 10 Gas Group B Distribution Section 11 Center of the outer peripheral opening end of the gas group A nozzle 12 Center of the outer peripheral opening end of the gas group B nozzle 13 Rotation axis center 14 Distance 15 angles

Claims

1. A surface-coated cutting tool having a substrate and a coating layer on a surface of the substrate, (a) the coating layer includes a layer of a composite nitride of Ti, Al, and V or a layer of a composite carbonitride having columnar crystal grains of an NaCl-type face-centered cubic structure, (b) The composite nitride or composite carbonitride is (Al Ｘ V Ｙ Ti １－Ｘ-Ｙ ) (C α N １－α ) (X, Y, α average value X ａｖｇ , Y ａｖｇ , α ａｖｇ are 0.600≦X ａｖｇ ≦0.950, 0.010≦Y ａｖｇ ≦0.300, 0.610≦X ａｖｇ +Y ａｖｇ ≦0.990, 0.0000≦α ａｖｇ ≦0.0050), (c) The composite nitride layer or composite carbonitride layer has crystal grains with a varying Al content, and the maximum value X of X in the crystal grains ｍａｘ * is the average value of X ｍａｘ and the minimum value X of X ｍｉｎ * is the average value of X ｍｉｎ However, 0.020≦X ｍａｘ -X ｍｉｎ ≦0.400 is satisfied, (d) A ＊ = 0.4045 x X ａｖｇ +0.4130 x Y ａｖｇ +0.4242×(1-X ａｖｇ -Y ａｖｇ ) A ＊ (nm) and the lattice constant A (nm) calculated from the XRD pattern, | A-A ＊ |<0.0010 (nm) A surface-coated cutting tool characterized by:

2. The composite nitride layer or composite carbonitride layer has crystal grains having both the Al content change and the V content change, and the maximum value Y of Y in the crystal grains ｍａｘ * is the average value of Y ｍａｘ and the minimum value Y ｍｉｎ * is the average value of Y ｍｉｎ However, 0.010≦Y ｍａｘ -Y ｍｉｎ 2. The surface-coated cutting tool according to claim 1, wherein the surface-coated cutting tool satisfies the following condition: ≦0.200.

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