Surface coated cutting tool

Abstract

To obtain a surface coated cutting tool which has excellent chipping resistance even when cutting a heat-resistant alloy.SOLUTION: A surface coated cutting tool has a substrate and a coating layer on the substrate, the coating layer has an upper layer, (a) an average thickness of the upper layer is 3.0 to 10.0 μm, (b) when an average composition of the upper layer is represented by (AlXavgTi1-Xavg)(CXcN1-Xc), the relationships of 0.70≤Xavg≤0.90 and 0.00≤XC≤0.05 are established, (c) both of Kurtosis values (Rku) of a rake face and a flank face of the upper layer is 3.0 or less, and (d) in the upper layer, a ratio of crystal grain having a NaCl type face-centered cubic structure is 80.0 area% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a surface-coated cutting tool (hereinafter sometimes referred to as a coated tool). [Background technology]

[0002] Conventionally, in order to extend the life of cutting tools, there are coated tools in which a coating layer is applied to the surface of a substrate such as a tungsten carbide (hereinafter sometimes referred to as WC)-based cemented carbide, and these coated tools have improved wear resistance, etc. In order to further improve the cutting performance of the coated tool, for example, proposals have been made regarding the surface roughness of the coating layer.

[0003] For example, Patent Document 1 describes a coated tool in which the root mean square slope (RΔq) of the surface of the coating layer is 0.060° or less, and the coated tool is said to have excellent wear resistance and high-temperature lubrication resistance.

[0004] For example, Patent Document 2 discloses a coating layer in which the maximum roughness height (R ZA ) is 0.5 to 1 μm, and skewness (R skA ) has a negative value, and the coated tool is said to have excellent wear resistance and fracture resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-208808 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-313636 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above circumstances and proposals, and has as its object to provide a surface-coated cutting tool that has excellent chipping resistance even when cutting heat-resistant alloys such as nickel-based alloys. [Means for solving the problem]

[0007] 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. the coating layer has a top layer; (a) the average thickness of the upper layer is 3.0 to 10.0 μm; (b) The average composition of the upper layer is (Al Xavg Ti 1-Xavg )(C Xc N 1-Xc ) when expressed as 0.70≦X avg ≦0.90 and 0.00≦X C ≦0.05, (c) the kurtosis (Rku) values ​​of the rake face and flank face of the upper layer are both 3.0 or less; (d) In the upper layer, the proportion of crystal grains having an NaCl-type face-centered cubic structure is 80.0% by area or more.

[0008] Furthermore, the surface-coated cutting tool according to the embodiment may satisfy at least one of the following (1) or (2).

[0009] (1) In the upper layer, the diffraction intensity value I(200) of the 200 diffraction line and the line intensity value I(111) of the 111 diffraction line of the crystal grains of the NaCl type face-centered cubic crystal structure are I(111)≦I(200).

[0010] (2) The coating layer has, in addition to the upper layer, at least one of a base layer, a lower layer, and an adhesive layer, in this order from the substrate toward the upper layer; (e) the underlayer is a Ti nitride layer and has an average thickness of 0.1 to 1.0 μm; (f) the lower layer is a Ti carbonitride layer and has an average thickness of 3.0 to 10.0 μm; (g) The adhesive layer has an average thickness of 0.2 to 5.0 μm and an average composition of (Al Yavg Ti 1-Yavg )(C Yc N 1-Yc ) when Y avg But 0.00 <Y avg ≦0.70, 0.10≦X avg -Y avg and 0.00≦Y C ≦0.05. [Effects of the Invention]

[0011] The surface-coated cutting tool according to the embodiment has excellent chipping resistance even when cutting Ni-based heat-resistant alloys and the like. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic vertical cross-sectional view of an example of a surface-coated cutting tool according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present inventors have conducted extensive research into ways to achieve better chipping resistance by specifying the surface roughness of the layer of the coating layer that comes into contact with the workpiece (if an identification layer for distinguishing whether the tool is used or unused is present on the surface, the layer immediately below that layer), as described in the prior art documents mentioned above. As a result, it was discovered that when the kurtosis (Rku) values ​​of the rake face and flank face of the layer in contact with the workpiece are at a predetermined value, the coated tool exhibits excellent chipping resistance.

[0014] Hereinafter, a coated tool according to an embodiment of the present invention will be described in detail. 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 unit for the lower limit is also the same.

[0015] In this specification, the term "longitudinal cross section" refers to the following: In the case of an insert, it refers to a cross section perpendicular to the surface of the substrate when the surface is treated as a flat surface, excluding any minute irregularities on the surface of the substrate. In addition, 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 if the substrate has a curved surface like a drill, if the tool diameter is sufficiently large compared to the thickness of the coating layer, the interface between the coating layer and the substrate in the measurement area will be approximately flat, and the surface of the substrate can be determined using the same method as for an insert.

[0016] FIG. 1 shows a schematic cross section of a coated tool according to one embodiment of the present invention. As is apparent from FIG. 1, the coated tool according to this embodiment includes a base layer (3) in contact with the surface of a substrate (1), a lower layer (4) in contact with the base layer (3) on the tool surface side of the base layer (3), an adhesion layer (5) in contact with the lower layer (4) on the tool surface side of the lower layer (4), and an upper layer (6) in contact with the adhesion layer (5) on the tool surface side of the adhesion layer (5). The base layer (3), intermediate layer (4), adhesion layer (5), and upper layer (6) constitute a coating layer (2). However, the base layer (3), lower layer (4), and adhesion layer (5) are each selectively provided, and none of them may be present in other embodiments. In other words, the coating layer may consist solely of the upper layer (5). Each layer will be described in turn below.

[0017] 1. Upper layer The upper layer is an essential layer in the coated tool of this embodiment.

[0018] (1) Average thickness The average thickness of the upper layer is preferably 3.0 to 10.0 μm. The reason is that if the average thickness is less than 3.0 μm, the desired wear resistance cannot be obtained, while if the average thickness is more than 10.0 μm, damage originating from cracks propagating toward the substrate when machining is continued with impacts or weld deposits during cutting processing becomes large, resulting in abnormal damage to the coated tool. The average thickness of the upper layer is more preferably 5.0 to 8.0 μm.

[0019] (2) Average composition The upper layer is either a Ti and Al composite nitride layer or a Ti and Al composite carbonitride layer (hereinafter, both may be collectively referred to as the (AlTi)CN layer), and its average composition is (Al Xavg Ti 1-Xavg )(C Xc N 1-Xc ), X avg However, 0.70≦X avg It is preferred that it is ≦0.90. The reason is that X avg If X is less than 0.70, the high oxidation resistance of (AlTi)N cannot be fully obtained, while if it exceeds 0.90, sufficient wear resistance and suppression of adhesion cannot be obtained. avg is more preferably 0.75 to 0.85.

[0020] The C component in the (AlTi)CN layer has the effect of improving the hardness of the upper layer. C The maximum value of X may be set to 0.05. C If X exceeds 0.05, the high-temperature strength of the upper layer decreases. C The upper limit is preferably 0.05 or less.

[0021] The atomic ratio of (AlTi) to CN is formed to be 1:1, but may be in the range of 1:0.8 to 1:1.2. This also applies to the composite nitride or composite carbonitride of Al and Ti that is used as an adhesive layer, which is selectively provided.

[0022] (3) Kurtosis (Rku) value The kurtosis (Rku) value of the rake face and flank face is preferably 3.0 or less. If the kurtosis (Rku) value exceeds 3.0, sharp convex portions (points) will be formed on the rake face and flank face, making chipping of the coating layer more likely to occur when cutting heat-resistant alloys. The lower limit of the kurtosis (Rku) value is preferably 0.0, but according to the production method according to the present embodiment described below, the lower limit of the kurtosis (Rku) value is about 1.5.

[0023] Here, the kurtosis (Rku) value is specified in ISO25178-2:2022 and is defined by the following formula:

[0024]

number

[0025] (4) NaCl-type face-centered cubic crystal grains In the upper layer, the proportion of crystal grains having an NaCl-type face-centered cubic crystal structure is preferably 80.0 area % or more. The reason is that if the proportion is below 80.0 area %, the proportion of crystal grains having a very soft wurtzite-type hexagonal crystal structure increases, making it impossible to ensure wear resistance and reducing cutting performance. A more preferable proportion is 90.0 area % or more. The upper limit may be 100.0 area % (meaning that all crystal grains have an NaCl-type face-centered cubic structure). The area ratio of crystal grains having an NaCl-type face-centered cubic structure is determined by the results of grain boundary determination, which will be described later.

[0026] (5) Average particle width The average grain width of the (AlTi)CN crystal grains constituting the upper layer is more preferably 0.03 to 2.00 μm. This is because if it is less than 0.03 μm, the number of peeling starting points in the upper layer increases, making it difficult to obtain the desired chipping resistance, and if it exceeds 2.00 μm, the peeling units in the upper layer become larger during cutting, resulting in a decrease in chipping resistance. The average grain width is even more preferably 0.10 to 1.80 μm. The average grain width is calculated using the results of grain boundary determination, which will be described later.

[0027] (6) X-ray diffraction intensity The upper composite nitride layer or composite carbonitride layer preferably has a diffraction intensity value I(200) of the 200 diffraction line and a diffraction intensity value I(111) of the 111 diffraction line, where I(111)≦I(200). The reason is that when I(111)>I(200), cracks are likely to occur during cutting, and the desired cutting performance cannot be fully obtained. Here, the hkl diffraction lines refer to diffraction lines observed as reflections of the (hkl) plane.

[0028] 2. Base layer, lower layer, adhesion layer The underlayer, lower layer, and adhesive layer are each selectively provided. In other words, it is not necessary to provide all of the underlayer, lower layer, and adhesive layer (only the upper layer may be coated on the substrate), and one or more of the underlayer, lower layer, and adhesive layer may be provided. For example, only the underlayer may be provided, or only the underlayer and adhesive layer, or all of the underlayer, lower layer, and adhesive layer may be provided.

[0029] (1) Base layer The underlayer is the layer closest to the substrate, is preferably a nitride of Ti (not limited to a stoichiometric composition), and serves to adhere the coating layer to the substrate. The average thickness of the underlayer is more preferably 0.1 to 1.0 μm, because if it is thinner than 0.1 μm, the adhesion may be insufficient, and if it exceeds 1.0 μm, it may be too thick and the coating layer may peel off more easily.

[0030] (2) Lower layer The lower layer is a carbonitride of Ti (not limited to a stoichiometric composition) and acts as a layer that ensures wear resistance. The average thickness of the lower layer is more preferably 3.0 to 10.0 μm. If the average thickness is less than 3.0 μm, the abrasion resistance of the lower layer is insufficient, and if it exceeds 10.0 μm, the coating layer may easily peel off.

[0031] (3) Adhesion layer The adhesion layer is a composite nitride layer or composite carbonitride layer of Al and Ti, and functions as a layer that improves the adhesive strength between the lower layer and the upper layer during cutting of the heat-resistant alloy. Its average thickness is preferably 0.2 to 5.0 μm. This is because a thickness below 0.2 μm fails to improve the adhesive strength between the lower layer and the upper layer, while a thickness above 5.0 μm makes the coating layer too thick and may actually cause peeling.

[0032] The average composition of the adhesive layer is (Al Yavg Ti 1-Yavg )(C Yc N 1-Yc ), Y avg But 0.00 <Y avg ≦0.70, 0.10≦X avg -Y avg and 0.00≦Y C It is preferred that it is ≦0.05. The reason is that if this relationship is satisfied, the presence of an adhesive layer promotes more continuous crystal growth between the lower and upper layers, thereby exhibiting chipping resistance. 0.00 <Y avg ≦0.70 and 0.10≦X avg -Y avg In this case, the adhesive layer has excellent adhesive strength to both the lower layer and the upper layer, and can exhibit excellent chipping resistance.

[0033] The C component in (AlTi)CN may be contained because it has the effect of improving the hardness of the adhesive layer. C If Y exceeds 0.05, the high-temperature strength of the adhesive layer decreases. C The upper limit is preferably 0.05 or less.

[0034] 3. Other layers (1) A group whose presence is desirable In addition to the underlayer, lower layer, adhesive layer, and upper layer, a surface layer may be selectively provided on the surface of the upper layer.

[0035] The surface layer can be, for example, a TiN layer. Since the TiN layer has a golden yellow color tone, it can be used as an identification layer to distinguish whether the coated tool is unused or used based on the color tone change on the surface of the coated tool. The average thickness of the TiN layer serving as the discrimination layer may be, for example, 0.1 to 1.0 μm.

[0036] (2) Layers that may occur accidentally In this embodiment, the films are formed so that there are no layers other than the underlayer, lower layer, adhesion layer, upper layer, and surface layer. However, when changing the type of layer to be formed, unintentional pressure changes (changes in gas pressure) or temperature fluctuations may occur within the film formation apparatus, and a layer with a different composition from these layers may be accidentally (unintentionally) formed between these layers. This layer is called a layer that may be accidentally formed.

[0037] 4.Base (1)Material The substrate used in this embodiment may be any known substrate material as long as it does not impede the achievement of the above-mentioned object. Examples include cemented carbide (WC-based cemented carbide, including those containing Co in addition to WC and further including those containing carbides or carbonitrides of Ti, Ta, Nb, etc.), cermet (containing TiC, TiN, TiCN, etc. as the main component), and ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.).

[0038] (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.

[0039] 5.Measurement method (1) Method for measuring kurtosis (Rku) value Using a shape measurement laser microscope, the kurtosis (Rku) of the rake face and flank of the upper layer is measured. The surface shape is measured using a 100x laser microscope, and the inclination of the surface being measured is corrected using the analysis function, and the kurtosis is measured.

[0040] (2) Method for determining the interface of each layer and measuring the average thickness A sample with a longitudinal cross section is cut out and polished. The polished longitudinal cross section is observed using a scanning electron microscope (SEM). The observation magnification is adjusted so that the entire coating layer in the thickness direction of the polished longitudinal cross section can be displayed on the SEM observation screen. Then, for example, the accelerating voltage is set to 1.5 kV, and secondary electron images are observed with an InLens detector to define the interfaces of each layer. Based on the defined interfaces, observations are made at five locations spaced at least 1.0 μm apart in the horizontal direction (parallel to the surface of the substrate), and the layer thickness of each layer is measured, and the average thickness is calculated.

[0041] (3) Method for measuring the average composition of the upper layer and the adhesive layer An electron probe (X-ray) microanalyzer (EPMA) is used to measure the average composition of each of the defined upper and adhesive layers. That is, an electron beam is irradiated onto a measurement point of each layer at least 1.0 μm away from the surface side of the longitudinal section of the sample, the characteristic X-rays generated are analyzed, the ratio of Al to the total amount of Al and Ti is determined, and the average of these content ratios is taken as the average Al content X. avg , Y avg Let's say.

[0042] Furthermore, the average C content (X C , Y CThe carbon content of the upper layer and the adhesive layer can be determined by secondary ion mass spectrometry (SIMS). Specifically, the carbon content is measured from the surface of the sample to the depth direction by alternately performing area analysis with an ion beam perpendicular to the surface of the upper layer and etching with a sputtered ion beam. Specifically, measurements are performed at least 0.05 μm deep in the upper layer and adhesive layer at intervals of 0.01 μm or less, starting from a point 0.05 μm or deeper, and the average value is calculated. This is performed at five or more points to determine the average carbon content of each layer. Similarly, the average contents of Al, Ti, and N in the upper layer and adhesive layer were measured for each layer by SIMS. Xavg Ti 1-Xavg ) and (C Xc N 1-Xc ) and (Al Yavg Ti 1-Yavg ) and (C Yc N 1-Yc ) can be calculated as follows:

[0043] (4) Method for defining the grain boundaries of the upper layer, method for identifying the crystal structure of each crystal grain, and method for measuring the cubic crystal area ratio The area ratio of crystal grains with a cubic crystal structure in the upper layer is determined as follows. First, using an SEM electron backscatter diffraction (EBSD) device (SEM-EBSD), the magnification is adjusted to allow the entire upper layer of the polished longitudinal cross section to be observed vertically and a sufficiently wide area of ​​the upper layer to be observed horizontally over a length of 50 μm. For example, the normal to the sample surface is tilted 70° relative to the incident beam, and an electron beam with an accelerating voltage of 15 kV and a probe current of 1 nA is irradiated at intervals of 0.01 μm / step to each crystal grain present within the measurement range of the polished cross section. The grain boundaries of each crystal grain appearing in the cross section can be determined from the obtained electron backscatter diffraction image. The crystal orientation of each crystal grain appearing in the cross section is identified using commercially available software, and the area ratio of crystal grains with a cubic crystal structure in the measurement area is determined.

[0044] (5) The method for measuring the average grain width of the upper layer and the method for calculating the average grain width W of the crystal grains will be explained. First, as mentioned above, the grain boundaries are determined in the longitudinal section to identify the crystal grains. Next, image processing is performed to determine the grain width W, which is the maximum length of a certain crystal grain i in the horizontal direction relative to the surface of the substrate. i , and area S i Ask for. The grain widths W1 to W of at least 20 grains within the observation field n Based on (n≧20), an area-weighted average is calculated using the following formula to determine the average grain width (area-based average grain size) W of the crystal grains.

[0045]

number

[0046] (5) Diffraction intensity value I The diffraction intensity values ​​I(111) and I(200) of the upper layer are measured using an X-ray diffraction device. The measurement conditions are, for example, Cu-Kα radiation, measurement range (2θ): 20 to 80 degrees, output 45 kV, 40 mA, step size 0.02 mm, scan step time 300 sec, detection distance 150 mm, and collimator diameter 100 μmΦ. The X-ray diffraction pattern is measured and the 111 and 200 diffraction intensity values ​​are calculated.

[0047] 6. Manufacturing method (1) Upper layer The manufacturing method of the upper layer can include, for example, two steps, an initial nucleus forming step and a crystal growth step, both of which use a CVD film formation method.

[0048] (1-1) Initial core forming process This is a process in which gas group A and gas group B are supplied at a predetermined cycle for a predetermined time to form nuclei of crystal grains that will form the coating layer. The following film formation conditions can be exemplified: % is volume %, and the sum of the percentages of the components in Gas Group A and Gas Group B is 100%.

[0049] Gas group A TiCl4: 0.01-0.03%, AlCl3: 0.03-0.08%, N2:0.0~10.0%, C2H4:0.0~0.5%, H2:Remaining Gas group B NH3: 0.04-0.16%, H2: 25.0-35.0% Reaction atmosphere pressure: 1.0 to 3.0 kPa Reaction atmosphere temperature: 700-850℃ Supply cycle: 1~5 seconds Gas supply time per cycle: 0.15 to 0.25 seconds Phase difference between gas group A supply and gas group B supply: 0.10 to 0.20 seconds

[0050] (1-2) Crystal growth process This is a step of growing the nuclei of the crystal grains formed in the initial nucleation step, in which gas group C and gas group D are supplied at a predetermined cycle for a predetermined time. The following film formation conditions can be exemplified: % is volume %, and the sum of the percentages of the components in gas group C and gas group D is 100%.

[0051] Gas group C TiCl4: 0.01 to 0.03%, AlCl3: 0.03 to 0.08%, N2:0.0~10.0%, C2H4:0.0~0.5%, H2:Remaining Gas group D NH3: 0.05-0.50%, H2: 25.0-35.0% Reaction atmosphere pressure: 1.0 to 5.0 kPa Reaction atmosphere temperature: 700-850℃ Supply cycle: 1~5 seconds, Gas supply time per cycle: 0.15 to 0.25 seconds Phase difference between gas group C supply and gas group D supply: 0.10 to 0.20 seconds

[0052] (2) Base layer The deposition conditions for the underlayer may be known, for example, the following deposition conditions by CVD (% is volume %): Gas composition: TiCl4: 3.0-5.0%, N2: 25.0-35.0%, H2: balance Reaction atmosphere pressure: 4.0 to 5.0 kPa Reaction atmosphere temperature: 780-900℃

[0053] (3) Lower layer The film formation conditions for the lower layer may be known. For example, the film formation conditions by the CVD method are as follows (% is volume %): Gas composition: TiCl4: 1.5-5.0%, N2: 8.0-25.0%, CH3CN: 0.5-1.0%, H2: balance Reaction atmosphere pressure: 4.0 to 10.0 kPa Reaction atmosphere temperature: 780-900℃

[0054] (4) Adhesion layer The film-forming conditions for the adhesive layer may be known, for example, the following film-forming conditions by CVD (% is volume %). Gas group E TiCl4: 0.01 to 0.10%, AlCl3: 0.01 to 0.03%, N2:0.0~10.0%, C2H4:0.0~0.5%, H2:Remaining Gas group F NH3: 0.04-0.16%, H2: 25.0-35.0% Reaction atmosphere pressure: 1.0 to 3.0 kPa Reaction atmosphere temperature: 700-850℃ Supply cycle: 1~5 seconds Gas supply time per cycle: 0.15 to 0.25 seconds Phase difference between gas group E supply and gas group F supply: 0.10 to 0.20 seconds

[0055] (5) Post-processing After the upper layer is formed, a blasting treatment is performed under the following conditions. This blasting treatment can reduce the kurtosis (Rku) values ​​of both the rake face and flank face of the upper layer to 3.0 or less. The particle size of the abrasive used in the post-treatment is defined in JIS R6001-2:2017. Abrasive grain: Al2O3 grain Abrasive grain size: #280~#600 Blast pressure: 0.25~0.40MPa Projection time: 4~16 seconds [Example]

[0056] Next, an example will be described. Here, we describe an application to an insert cutting tool using a WC-based cemented carbide as the substrate, but the substrate may be made of other materials as mentioned above, or may have other shapes such as a drill.

[0057] WC powder, TaC powder, NbC powder, Cr3C2 powder, and Co powder were prepared as raw material powders. These raw material powders were blended 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 specified shape at a pressure of 98 MPa. This green compact was then vacuum sintered at 1400°C in a vacuum of 5 Pa for 1 hour. After sintering, WC-based cemented carbide substrates A to C with the insert shape of ISO standard CNMG120408 were produced.

[0058] On this substrate, an underlayer, a lower layer, and an adhesive layer were selectively formed, and then an upper layer was formed, thereby obtaining Examples 1 to 10. The film formation conditions were as follows.

[0059] base layer The details are shown in Table 8, but the general outline was as follows: The gas composition was TiCl4: 3.0 to 5.0%, N2: 25.0 to 35.0%, H2: balance, the reaction atmosphere pressure was 4.0 to 5.0 kPa, and the reaction atmosphere temperature was 780 to 900°C.

[0060] Lower layer The details are shown in Table 9, but the general outline was as follows: The gas composition was TiCl4: 1.5-5.0%, N2: 8.0-25.0%, CH3CN: 0.5-1.0%, H2: balance, reaction atmosphere pressure: 4.0-10.0 kPa, reaction atmosphere temperature: 780-900°C.

[0061] Adhesion layer The details are shown in Tables 6 and 7, but the general outline was as follows: Gas group E consisted of TiCl4: 0.01-0.10%, AlCl3: 0.01-0.03%, N2: 0.0-10.0%, C2H4: 0.0-0.5%, and the balance was H2; gas group F consisted of NH3: 0.04-0.16%, H2: 25.0-35.0%, reaction atmosphere pressure: 1.0-3.0 kPa, reaction atmosphere temperature: 700-850°C, supply cycle: 1-5 seconds, gas supply time per cycle: 0.15-0.25 seconds, and phase difference between the supply of gas group E and the supply of gas group F: 0.10-0.20 seconds; and film formation was performed for a specified time.

[0062] upper layer The detailed film formation conditions are shown in Tables 2 to 5, but were generally as follows. The initial nucleus formation process was carried out with gas group A containing TiCl4: 0.01-0.03%, AlCl3: 0.03-0.08%, N2: 0.0-10.0%, C2H4: 0.0-0.5%, and the balance being H2; gas group B containing NH3: 0.04-0.16%, H2: 25.0-35.0%, reaction atmosphere pressure: 1.0-3.0 kPa, reaction atmosphere temperature: 700-850°C, supply cycle: 1-5 seconds, gas supply time per cycle: 0.15-0.25 seconds, and phase difference between the supply of gas group A and the supply of gas group B: 0.10-0.20 seconds, and film formation was carried out for a predetermined time.

[0063] The crystal growth process was carried out with gas group C containing TiCl4: 0.01-0.03%, AlCl3: 0.03-0.08%, N2: 0.0-10.0%, C2H4: 0.0-0.5%, and the balance H2; gas group D containing NH3: 0.05-0.50%, H2: 25.0-35.0%, reaction atmosphere pressure: 1.0-5.0 kPa, reaction atmosphere temperature: 700-850°C, supply cycle: 1-5 seconds, gas supply time per cycle: 0.15-0.25 seconds, and phase difference between the supply of gas group C and the supply of gas group D: 0.10-0.20 seconds, and film formation was carried out for a specified time.

[0064] Post-processing The upper layer was subjected to blasting under the conditions shown in Table 10.

[0065] For comparison, an upper layer was formed on the substrate shown in Table 1 under the conditions shown in Tables 2 to 5, and an underlayer, lower layer, and adhesive layer were formed as necessary in the same manner as in the examples to produce Comparative Examples 1 to 10.

[0066] The average thickness of each layer, the average composition and diffraction intensity value I of the upper layer and adhesive layer, and the kurtosis (Rku) values ​​of the rake face and flank face of the upper layer were measured as described above.

[0067] [Table 1]

[0068] In Table 1, "-" indicates that no compound was added.

[0069] [Table 2]

[0070] [Table 3]

[0071] [Table 4]

[0072] [Table 5]

[0073] [Table 6]

[0074] [Table 7]

[0075] [Table 8]

[0076] [Table 9]

[0077] [Table 10]

[0078] In comparative example step e, no post-treatment step was carried out.

[0079] [Table 11]

[0080] Next, for Examples 1 to 10 and Comparative Examples 1 to 10, the various tool substrates A to C (shaped as per ISO standard CNMG120408) were all clamped to the tip of a tool steel bit with a fixing jig, and the flank damage width was measured every minute after the start of the cutting test. The cause of damage exceeding the specified damage width (0.2 mm) was visually observed, and the cutting time until the end of life was measured.

[0081] When the flank damage width ultimately exceeded 0.2 mm due to chipping, the elapsed time (measurement time) from the start of the test when it exceeded 0.2 mm was taken as the cutting time leading to the end of life. If the flank damage width ultimately exceeds 0.2 mm due to wear, the flank damage width at the time elapsed from the start of the test (measurement time) that exceeds 0.2 mm and the flank damage width at the measurement time immediately preceding this time are linearly approximated to determine the time elapsed from the start of the test that gives a flank damage width of 0.2 mm (cutting time until end of life). The results of the cutting test are shown in Table 12. Note that for the comparative example, chipping occurred and the tool reached the end of its life before the end of the cutting time, so the time until the tool reached its end of life is shown.

[0082] Cutting processing test Workpiece material: Ni-19Cr-19Fe-3Mo-0.9Ti-0.5Al-5.1(Nb+Ta) alloy (numbers indicate mass %) Cutting speed: 140m / min Cutting depth: 0.30 mm Feed rate: 0.11 mm / rev Cutting time: 14 minutes Wet method

[0083] [Table 12]

[0084] As is clear from the results shown in Table 12, all of the examples exhibited excellent durability with no chipping of the coating layer even when subjected to cutting of difficult-to-cut materials. In contrast, in all of the comparative examples, chipping occurred due to the load during high-speed cutting, resulting in a short tool life. [Explanation of symbols]

[0085] 1 Base 2 Covering layer 3 Base layer 4 Lower layer 5 Adhesion layer 6 Upper layer

Claims

1. A substrate and a coating layer on the surface of the substrate are included. the coating layer has a top layer; (a) the average thickness of the upper layer is 3.0 to 10.0 μm; (b) the average composition of the upper layer is (Al Ｘavg Ti １－Ｘavg ) (C Ｘｃ N １－Ｘｃ ) when expressed as 0.70≦X ａｖｇ ≦0.90 and 0.00≦X Ｃ ≦0.05, (c) the kurtosis (Rku) values ​​of the rake face and flank of the upper layer are both 3.0 or less; (d) In the upper layer, the proportion of crystal grains having an NaCl type face-centered cubic structure is 80.0% by area or more. A surface-coated cutting tool characterized by:

2. 2. The surface-coated cutting tool according to claim 1, wherein in the upper layer, the diffraction intensity value I(200) of the 200 diffraction line and the line intensity value I(111) of the 111 diffraction line of the crystal grains of the NaCl type face-centered cubic crystal structure satisfy I(111)≦I(200).

3. the coating layer has, in addition to the upper layer, at least one of a base layer, a lower layer, and an adhesive layer, in this order from the substrate toward the upper layer; (e) the underlayer is a Ti nitride layer and has an average thickness of 0.1 to 1.0 μm; (f) the lower layer is a Ti carbonitride layer, and its average thickness is 3.0 to 10.0 μm; (g) The adhesive layer has an average thickness of 0.2 to 5.0 μm and an average composition of (Al Ｙａｖｇ Ti １－Ｙａｖｇ ) (C Ｙｃ N １－Ｙｃ ) when expressed as Y ａｖｇ but, 0.00<Y ａｖｇ ≦0.70 and 0.10≦X ａｖｇ -Y ａｖｇ and 0.00≦Y Ｃ ≦0.05 4. The surface-coated cutting tool according to claim 1, wherein

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