Cutting tool

Abstract

To provide a cutting tool.SOLUTION: A cutting tool comprises a base material, and a coating film located on the base material. The coating film includes a first layer, the base material includes a hard phase and a binder phase, the hard phase includes tungsten carbide particles, the binder phase includes cobalt metal, and the first layer includes aluminum oxide or titanium aluminum nitride. The base material has a first area. The first area is an area sandwiched between a boundary face between the base material and the coating film, and a virtual surface VS1 which passes through a position separated toward the base material side from the boundary surface by 0.5 μm and is parallel to the boundary surface. A ratio of a sum of lengths of a straight line and line segments located on the binder phase to a length of the straight line included in a virtual surface VS2 in which a distance from the boundary surface and a distance from the virtual surface VS1 are equal is 50% or more and 90% or less, and a roughness Rz of a surface of the base material in contact with the coating film is 1.0 μm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a cutting tool.

Background Art

[0002] Conventionally, a cutting tool including a base material and a coating disposed on the base material has been used for cutting (Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0004] The cutting tool of the present disclosure is a cutting tool including a base material and a coating disposed on the base material, the coating includes a first layer, the base material is composed of a hard phase and a binder phase, the hard phase is composed of tungsten carbide particles, the binder phase is composed of metallic cobalt, the first layer is composed of aluminum oxide or titanium aluminum nitride, the base material has a first region, the first region is a region sandwiched between an interface between the base material and the coating and a virtual plane VS1 passing through a position 0.5 μm away from the interface toward the base material side and parallel to the interface, the ratio occupied by the total length of line segments located in the straight line and the binder phase with respect to the length of a straight line included in a virtual plane VS2 where the distance from the interface and the distance from the virtual plane VS1 are equal is 50% or more and 90% or less, the roughness Rz of the surface of the base material in contact with the coatingJIS is 1.0 μm or less.

Brief Description of the Drawings

[0005]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0006] [Problems to be Solved by the Present Disclosure] In recent years, the demand for improving tool life has been increasing more and more. In particular, even in interrupted turning of cast iron, further improvement of tool life is required. As important factors for further improving tool life in interrupted turning of cast iron, "wear resistance" and "chipping resistance" can be mentioned. Further, from the viewpoint of improving wear resistance, in interrupted turning of cast iron, a cutting tool including a base material and a coating disposed on the base material, the coating includes a first layer, the base material is composed of a hard phase and a binder phase, the hard phase is composed of tungsten carbide particles, the binder phase is composed of metallic cobalt, and the first layer is composed of aluminum oxide or titanium aluminum nitride has been used. However, in such a coating, since the coating tends to peel off easily, the "chipping resistance" may not be sufficient. Further, wear may easily occur due to minute damage caused by insufficient "chipping resistance" (that is, the "wear resistance" may not be sufficient). Therefore, it is required to extend the tool life, particularly in interrupted turning of cast iron, by combining excellent "wear resistance" and excellent "chipping resistance".

[0007] Therefore, an object of the present disclosure is to provide a cutting tool having a long tool life, particularly in interrupted turning of cast iron.

[0008] [Effects of the Present Disclosure] According to the present disclosure, it is possible to provide a cutting tool having a long tool life, particularly in interrupted turning of cast iron.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. (1) The cutting tool of the present disclosure is a cutting tool including a substrate and a coating disposed on the substrate, the coating includes a first layer, the substrate is composed of a hard phase and a binder phase, the hard phase is composed of tungsten carbide particles, the binder phase is composed of metallic cobalt, the first layer is composed of aluminum oxide or titanium aluminum nitride, the substrate has a first region, the first region is a region sandwiched between an interface between the substrate and the coating and a virtual plane VS1 passing through a position 0.5 μm away from the interface toward the substrate side and parallel to the interface, the ratio of the total length of line segments located on the straight line and the binder phase to the length of the straight line included in a virtual plane VS2 where the distance from the interface and the distance from the virtual plane VS1 are equal is 50% or more and 90% or less, the roughness Rz of the surface of the substrate in contact with the coating JIS is 1.0 μm or less.

[0010] According to the present disclosure, it is possible to provide a cutting tool having a long tool life, particularly in interrupted turning of cast iron.

[0011] (2) In the above (1), the ratio of the total length of the line segments located in the straight line and the bonding phase to the length of the straight line included in the virtual plane VS2 where the distance from the interface and the distance from the virtual plane VS1 are equal is measured in a cross-section along the normal direction of the interface between the base material and the coating, The roughness Rz of the surface of the base material in contact with the coating JIS can be measured in accordance with JIS B0601:2001 in the cross-section along the normal direction of the interface between the base material and the coating.

[0012] (3) In the above (1) or (2), the base material has a second region, The second region is a region sandwiched between the interface between the base material and the coating and a virtual plane VS3 that passes through a position 2.0 μm away from the interface on the base material side and is parallel to the interface, The ratio of the voids in the second region may be 0% by volume or more and 1.5% by volume or less. Thereby, a cutting tool having a longer tool life can be provided, particularly in interrupted turning of cast iron.

[0013] (4) In the above (3), the ratio of the voids in the second region can be measured in a cross-section along the normal direction of the interface between the base material and the coating.

[0014] (5) In any of the above (1) to (4), the coating further includes a second layer, The first layer is disposed on the second layer, The second layer may be made of titanium carbonitride. Thereby, a cutting tool having a longer tool life can be provided, particularly in interrupted turning of cast iron.

[0015] (6) In the above (5), the thickness of the second layer may be more than 0 μm and 10 μm or less. Thereby, a cutting tool having a longer tool life can be provided, particularly in interrupted turning of cast iron.

[0016] (7) In any one of (1) to (6) above, the thickness of the first layer may be 2.0 μm or more and 10 μm or less. Thereby, a cutting tool having a longer tool life can be provided, particularly in intermittent turning of cast iron.

[0017] (8) In any one of (1) to (7) above, the particle size of the tungsten carbide particles may be 0.3 μm or more and 3.0 μm or less. Thereby, a cutting tool having a longer tool life can be provided, particularly in intermittent turning of cast iron.

[0018] (9) In any one of (1) to (8) above, the base material may contain 8.0 vol% or more and 20 vol% or less of the binder phase. Thereby, a cutting tool having a longer tool life can be provided, particularly in intermittent turning of cast iron.

[0019] [Details of Embodiments of the Present Disclosure] A specific example of a cutting tool according to an embodiment of the present disclosure (hereinafter, also referred to as "this embodiment") will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals represent the same or corresponding parts. Also, dimensional relationships such as length, width, thickness, and depth are appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0020] In the present disclosure, the notation in the form of "A to B" means the upper and lower limits of the range (that is, A or more and B or less). When there is no unit description for A and there is a unit description only for B, the units of A and B are the same.

[0021] In the present disclosure, when representing a compound or the like by a chemical formula, when the atomic ratio is not particularly limited, it includes all conventionally known atomic ratios and should not necessarily be limited only to those within the stoichiometric range.

[0022] [Embodiment 1: Cutting Tool] A cutting tool according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 3. One embodiment of the present disclosure (hereinafter also referred to as "this embodiment") is a cutting tool 10 including a base material 1 and a coating 2 disposed on the base material 1, the coating 2 includes a first layer 3, the base material 1 is composed of a hard phase and a binder phase, the hard phase is composed of tungsten carbide particles, the binder phase is composed of metallic cobalt, the first layer 3 is composed of aluminum oxide or titanium aluminum nitride, the base material 1 has a first region R1, the first region R1 is a region sandwiched between an interface between the base material 1 and the coating 2 and a virtual plane VS1 passing through a position 0.5 μm away from the interface on the base material 1 side and parallel to the interface, the ratio of the total length of line segments located on the straight line and the binder phase (hereinafter also referred to as "L2") to the length of a straight line included in a virtual plane VS2 having the same distance from the interface and the virtual plane VS1 (hereinafter also referred to as "L1") is 50% or more and 90% or less, the roughness Rz of the surface of the base material 1 in contact with the coating 2 JIS is 1.0 μm or less.

[0023] According to the present disclosure, it is possible to provide a cutting tool having a long tool life, particularly in interrupted turning of cast iron. The reason is presumed as follows.

[0024] (a) The base material 1 has a first region R1, and the first region R1 is a region sandwiched between an interface between the base material 1 and the coating 2 and a virtual plane VS1 passing through a position 0.5 μm away from the interface on the base material 1 side and parallel to the interface. The ratio of the total length of line segments located on the straight line and the binder phase (L2) to the length of a straight line included in a virtual plane VS2 having the same distance from the interface and the virtual plane VS1 (L1) is 50% or more and 90% or less. Thereby, the adhesion between the base material 1 and the coating 2 is improved, so that "wear resistance" and "chipping resistance" can be improved.

[0025] (b) Roughness Rz of the surface of the base material 1 in contact with the coating 2 JIS is 1.0 μm or less. As a result, the coating 2 is likely to be formed homogeneously, improving the strength of the coating 2, thereby improving "abrasion resistance" and "defect resistance".

[0026] That is, according to the present disclosure, since the cutting tool 10 can have excellent "abrasion resistance" and excellent "defect resistance", it is possible to provide a cutting tool with a long tool life, especially in interrupted turning of cast iron.

[0027] ≪Cutting tool≫ As shown in FIGS. 1 to 3, a cutting tool 10 according to an embodiment of the present disclosure includes a base material 1 and a coating 2 disposed on the base material 1. The coating 2 may cover the entire surface of the base material 1, but even if a part of the base material 1 is not covered by the coating 2 or the configuration of the coating 2 is partially different, it does not deviate from the scope of the present embodiment. When a part of the base material 1 is not covered by the coating 2, the coating 2 may be disposed so as to cover at least the surface of the part of the base material 1 involved in cutting. In this specification, the part of the base material 1 involved in cutting depends on the size and shape of the base material 1, but in the base material 1, the cutting edge ridge line and the distance along the perpendicular to the tangent line of the cutting edge ridge line from the cutting edge ridge line to the base material 1 side, for example, 5 mm, 3 mm, 2 mm, 1 mm, 0.5 mm, means the region surrounded by the virtual surface that is any one of them.

[0028] The cutting tool 10 of the present embodiment can be suitably used as a cutting tool 10 such as a drill, an end mill, a cutting tip for drill with replaceable cutting edge, a cutting tip for end mill with replaceable cutting edge, a cutting tip for milling with replaceable cutting edge, a cutting tip for turning with replaceable cutting edge, a metal saw, a tooth cutting tool, a reamer, a tap, etc.

[0029] ≪Base material≫ The substrate 1 is composed of a hard phase and a binder phase. Here, "composed of a hard phase and a binder phase" means that other hard phases (for example, carbides, nitrides, carbonitrides, and mixtures thereof such as Ti, Ta, Nb, etc.) may be included as long as the effects of the present disclosure are not impaired.

[0030] The substrate 1 may contain 80% by volume or more and 92% by volume or less of the hard phase. In other words, the content of the hard phase in the substrate 1 may be 80% by volume or more and 92% by volume or less. Thereby, the cutting tool 1 can have a longer tool life, particularly in interrupted turning of cast iron. The lower limit of the content of the hard phase in the substrate 1 may be 80% by volume or more, may be 81% by volume or more, or may be 82% by volume or more. The upper limit of the content of the hard phase in the substrate 1 may be 92% by volume or less, may be 91% by volume or less, or may be 90% by volume or less. The content of the hard phase in the substrate 1 may be 81% by volume or more and 91% by volume or less, or may be 82% by volume or more and 90% by volume or less.

[0031] The substrate 1 may contain 8.0% by volume or more and 20% by volume or less of the binder phase. In other words, the content of the binder phase in the substrate 1 may be 8.0% by volume or more and 20% by volume or less. Thereby, the cutting tool 1 can have a longer tool life, particularly in interrupted turning of cast iron. The lower limit of the content of the binder phase in the substrate 1 may be 8.0% by volume or more, may be 9.0% by volume or more, or may be 10.0% by volume or more. The upper limit of the content of the binder phase in the substrate 1 may be 20% by volume or less, may be 19% by volume or less, or may be 18% by volume or less. The content of the binder phase in the substrate 1 may be 9.0% by volume or more and 19% by volume or less, or may be 10.0% by volume or more and 18% by volume or less.

[0032] The "content ratio of the hard phase in the base material 1" and the "content ratio of the bonding phase in the base material 1" are specified by the following method. First, on an arbitrary cross-section of the base material 1, a photographed image at 5000 times magnification is obtained using a scanning electron microscope (SEM). In the photographed image, an arbitrary "rectangular field of view of 10 μm × 10 μm" is specified. Next, in the rectangular field of view, the area of the hard phase and the area of the bonding phase are each measured using image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ). Next, the "content ratio of the hard phase in the base material 1" is specified by calculating the ratio of the area of the hard phase to the area of the rectangular field of view as a percentage. Also, the "content ratio of the bonding phase in the base material 1" is specified by calculating the ratio of the area of the bonding phase to the area of the rectangular field of view as a percentage. Note that as long as the measurement is performed on the same base material 1, it has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0033] <Hard phase> The hard phase is composed of tungsten carbide particles. As a result, since the base material 1 is particularly excellent in the balance between hardness and strength at high temperatures, when used in the cutting tool 10, it can contribute to extending the service life of the cutting tool 10. Here, "composed of tungsten carbide particles" means that other metal elements, precipitates, etc. may be included as long as the effects of the present disclosure are not impaired. Examples of other metal elements include Ni, Cr, Fe, etc. Examples of precipitates include TiC, TiCN, NbC, etc.

[0034] In the cutting tool 10, the composition of the hard phase can be specified by performing mapping analysis on an arbitrary cross-section of the base material 1 using energy dispersive X-ray analysis (EDS) attached to a scanning electron microscope (SEM). Note that as long as the measurement is performed on the same base material 1, it has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0035] The particle size of the tungsten carbide particles may be 0.3 μm or more and 3.0 μm or less. Thereby, it becomes easier to have an excellent balance between hardness and toughness. Therefore, the cutting tool 1 has a longer tool life especially in interrupted turning of cast iron. The lower limit of the particle size of the tungsten carbide particles may be 0.3 μm or more, may be 0.5 μm or more, or may be 0.7 μm or more. The upper limit of the particle size of the tungsten carbide particles may be 3.0 μm or less, may be 2.6 μm or less, or may be 2.5 μm or less. The particle size of the tungsten carbide particles may be 0.5 μm or more and 2.6 μm or less, or may be 0.7 μm or more and 2.5 μm or less.

[0036] The particle size of the tungsten carbide particles can be specified by the following method. First, an arbitrary cross-section of the base material 1 is obtained, and a processed surface is obtained by performing mirror finishing on the cross-section. Next, an image of the processed surface is taken at a magnification of 5000 times using a scanning electron microscope to obtain a photographed image. Next, for an arbitrary "20 μm × 20 μm rectangular measurement field" in the photographed image, the particle sizes (Heywood diameter: equivalent diameter of an equal-area circle) of 20 WC particles are measured using image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ). Next, the same measurement is performed for each of the other four arbitrary "20 μm × 20 μm rectangular measurement fields" in the photographed image. Next, the "particle size of the tungsten carbide particles" is obtained by calculating the average value of the particle sizes (Heywood diameter: equivalent diameter of an equal-area circle) of 100 WC in total.

[0037] <Binder phase> The binder phase is made of metallic cobalt. Here, "made of metallic cobalt" means that other metal elements, precipitates, etc. may be included as long as the effects of the present disclosure are not impaired. Examples of other metal elements include Ni, Cr, Fe, etc. Examples of precipitates include TiC, TiCN, NbC, etc.

[0038] In the cutting tool 10, the composition of the binder phase can be specified by performing mapping analysis on an arbitrary cross section using EDS attached to the SEM.

[0039] <The roughness Rz of the surface of the substrate in contact with the coating JIS > The roughness Rz of the surface of the substrate 1 in contact with the coating 2 JIS is 1.0 μm or less. Thereby, "wear resistance" and "chipping resistance" can be improved. The roughness Rz of the surface of the substrate 1 in contact with the coating 2 JIS The lower limit may be 0 μm or more, but from a manufacturing perspective, it can be, for example, 0.1 μm or more, 0.2 μm or more, 0.3 μm or more. The roughness Rz of the surface of the substrate 1 in contact with the coating 2 JIS The upper limit may be 0.9 μm or less, 0.8 μm or less, 0.7 μm or less. The roughness Rz of the surface of the substrate 1 in contact with the coating 2 JIS may be 0 μm or more and 1.0 μm or less, 0 μm or more and 0.9 μm or less, 0 μm or more and 0.8 μm or less.

[0040] The roughness Rz of the surface of the substrate 1 in contact with the coating 2 JIScan be measured in accordance with JIS B0601:2001 in a cross-section along the normal direction of the interface between the substrate 1 and the coating 2. More specifically, first, an image is obtained by imaging at a magnification of 1000 times using SEM in a cross-section along the normal direction of the interface between the substrate 1 and the coating 2. Next, in the image, at a magnification of 10000 times, any one observation field of a 10 μm × 10 μm rectangle including the interface is specified. In the observation field, assume that the interface passes through any one set of two opposite sides. Next, for the observation field, the "ten-point mean roughness of the interface" in the observation field is specified by extracting the contour information of the interface using image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ). Next, in the above image, for any other four observation fields, the "ten-point mean roughness of the interface" is specified. Next, the roughness Rz of the surface of the substrate 1 in contact with the coating 2 is specified by calculating the average value of the "ten-point mean roughness of the interface" in a total of five observation fields. JIS is specified.

[0041] Note that as long as the measurement is performed with the same cutting tool 10, it has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0042] <First Region> The substrate 1 has a first region R1. The first region R1 is a region sandwiched between the interface between the substrate 1 and the coating 2 and a virtual plane VS1 that passes through a position 0.5 μm away from the interface on the substrate 1 side and is parallel to the interface.

[0043] The ratio that the total length (L2) of the line segments located on the straight line and the bonding phase occupies with respect to the length (L1) of the straight line included in the virtual plane VS2 where the distance from the above interface and the distance from the above virtual plane VS1 are equal is 50% or more and 90% or less. Thereby, the "wear resistance" and "chipping resistance" of the cutting tool 1 can be improved. The lower limit of the ratio may be 55% or more, may be 60% or more, or may be 65% or more. The upper limit of the ratio may be 85% or less, may be 80% or less, or may be 75% or less. The ratio may be 55% or more and 85% or less, may be 60% or more and 80% or less, or may be 65% or more and 75% or less. In FIG. 1, the "distance between the interface of the base material 1 and the coating 2 and the virtual plane VS2" is denoted as D1. Also, in FIG. 1, the "distance between the virtual plane VS2 and the virtual plane VS1" is denoted as D2. "The distance from the above interface and the distance from the above virtual plane VS1 are equal" can be rephrased as D1 and D2 being equal.

[0044] The ratio that the total length (L2) of the line segments located on the straight line and the bonding phase occupies with respect to the length (L1) of the straight line included in the virtual plane VS2 where the distance from the above interface and the distance from the above virtual plane VS1 are equal can be measured in a cross-section along the normal direction of the interface between the base material 1 and the coating 2. More specifically, first, regarding the cross-section, using a scanning electron microscope, an observation image is taken at a magnification of 1000 times. Next, an arbitrary "20 μm × 20 μm rectangular field of view" in the observation image is specified. Here, the above straight line shall pass through any one pair of opposite sides in the rectangular field of view. Next, on the above straight line in the rectangular field of view, using image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ), L1 and L2 are measured. Next, the ratio (L2 / L1) × 100 that L2 occupies with respect to L1 is calculated.

[0045] Note that as long as the measurement is performed on the same cutting tool 10, it has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0046] <Second Region> The base material 1 has a second region R2, and the second region R2 is a region sandwiched between the interface between the base material 1 and the coating 2 and a virtual plane VS3 that passes through a position 2.0 μm away from the interface toward the base material 1 side and is parallel to the interface. The proportion of voids in the second region R2 may be 0% by volume or more and 1.5% by volume or less. Thereby, since a decrease in the strength of the base material 1 is likely to be suppressed, the cutting tool 1 has a longer tool life especially in interrupted turning of cast iron. The lower limit of the proportion may be 0% by volume or more, 0.2% by volume or more, or 0.3% by volume or more. The upper limit of the proportion may be 1.5% by volume or less, 1.3% by volume or less, or 1.1% by volume or less. The proportion may be 0.2% by volume or more and 1.3% by volume or less, or 0.3% by volume or more and 1.1% by volume or less.

[0047] The proportion of voids in the second region R2 can be measured in a cross-section along the normal direction of the interface between the base material 1 and the coating 2. More specifically, first, an image is obtained by imaging at a magnification of 1000 times using SEM in a cross-section along the normal direction of the interface between the base material 1 and the coating 2. Next, in the image, at a magnification of 10000 times, any one observation field of a 10 μm × 10 μm rectangle is specified. In the observation field, it is assumed that the interface passes through any one pair of opposite sides. Next, for the observation field, using image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ), the area of the "second region R2" and the area of the "voids in the second region R2" in the observation field are specified. Next, the proportion of the area of the "voids in the second region R2" to the area of the "second region R2" is calculated as a percentage. Next, in the above image, for any other four observation fields, the proportion of the area of the "voids in the second region R2" to the area of the "second region R2" is calculated as a percentage. Next, the "proportion of voids in the second region R2" is specified by calculating the average value of the proportions of the area of the "voids in the second region R2" to the area of the "second region R2" in a total of five observation fields.

[0048] Incidentally, as long as the measurement is made with the same cutting tool 10, it has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0049] ≪Coating≫ <Shape of the coating> The thickness of the coating 2 may be 2.0 μm or more and 20 μm or less. If the lower limit of the thickness of the coating 2 is less than 2.0 μm, the tool life tends to be insufficient. If the upper limit of the thickness of the coating 2 exceeds 20 μm, stress is likely to occur in the coating 2 during cutting, and peeling or breakage is likely to occur. The lower limit of the thickness of the coating 2 may be 2.0 μm or more, 3.0 μm or more, or 4.0 μm or more. The upper limit of the thickness of the coating 2 may be 20 μm or less, 19 μm or less, or 18 μm or less. The thickness of the coating 2 may be 3.0 μm or more and 19 μm or less, or 4.0 μm or more and 18 μm or less.

[0050] The thickness of the coating 2 can be specified by the following method. It can be measured by observing a cross section along the normal direction of the interface between the substrate 1 and the coating 2 using a scanning electron microscope (SEM). Specifically, the observation magnification of the cross-sectional sample is set to 1000 times, the observation field of view is set to a rectangular field of view of 120 μm × 100 μm, the thickness widths at three locations in one field of view are measured, and the average value is taken as the "thickness". The same applies to the thickness of each layer described below unless otherwise specified.

[0051] Incidentally, as long as the measurement is made with the same cutting tool 10, it has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0052] ≪First layer≫ <Composition of the first layer> The coating 2 includes a first layer 3. The first layer 3 is made of aluminum oxide or aluminum titanium nitride. Thereby, the reaction between the cutting tool 10 and the workpiece can be suppressed. Here, "made of aluminum oxide or aluminum titanium nitride" means that other components may be included as long as the effects of the present disclosure are not impaired. Examples of other components include C atoms, Cr atoms, and the like.

[0053] The composition of the first layer 3 can be specified by performing point analysis on an arbitrary cross-section using EDS attached to the SEM. It should be noted that as long as the measurement is performed on the same cutting tool 10, it has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0054] <Shape of the first layer> The thickness of the first layer 3 may be 2.0 μm or more and 10 μm or less. Thereby, the effect of the coating 2 can be maximized. The lower limit of the thickness of the first layer 3 may be 2.0 μm or more, 3.0 μm or more, or 4.0 μm or more. The upper limit of the thickness of the first layer 3 may be 10 μm or less, 9 μm or less, or 8 μm or less. The thickness of the first layer 3 may be 3.0 μm or more and 9 μm or less, or 4.0 μm or more and 8 μm or less.

[0055] ≪Second layer≫ <Composition of the second layer> The coating 2 further includes a second layer 4. The first layer 3 is disposed on the second layer 4, and the second layer 4 may be made of titanium carbonitride. Thereby, the cutting tool 1 can have a longer tool life, especially in interrupted turning of cast iron. Here, "made of titanium carbonitride" means that other components may be included as long as the effects of the present disclosure are not impaired. Examples of other components include Si atoms and the like.

[0056] The composition of the second layer 4 can be specified by performing point analysis on an arbitrary cross-section using EDS attached to the SEM. It should be noted that as long as the measurement is performed with the same cutting tool 10, it has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0057] <Shape of the second layer> The thickness of the second layer 4 may be more than 0 μm and 10 μm or less. Thereby, the cutting tool 1 can have a longer tool life, particularly even in interrupted turning of cast iron. The lower limit of the thickness of the second layer 4 may be more than 0 μm, may be 1 μm or more, or may be 2 μm or more. The upper limit of the thickness of the second layer 4 may be 10 μm or less, may be 9 μm or less, or may be 8 μm or less. The thickness of the second layer 4 may be 1 μm or more and 9 μm or less, or may be 2 μm or more and 8 μm or less.

[0058] ≪Base layer≫ <Composition of the base layer> The coating 2 further includes a base layer 5 in contact with the substrate 1, and the base layer 5 may be made of titanium nitride. Thereby, a longer tool life can be achieved, particularly even in interrupted turning of cast iron. In the case where the coating 2 further includes the base layer 5 in contact with the substrate 1 and the coating 2 further includes the second layer 4, the second layer 4 is disposed on the base layer 5, and the first layer 3 is disposed on the second layer 4. In the case where the coating 2 further includes the base layer 5 in contact with the substrate 1 and the coating 2 does not include the second layer 4, the first layer 3 is disposed on the base layer 5. Here, "made of titanium nitride" means that other components may be included as long as the effects of the present disclosure are not impaired. Examples of other components include O atoms.

[0059] The composition of the base layer 5 can be specified by performing point analysis on an arbitrary cross-section using EDS attached to the SEM. It should be noted that as long as the measurement is performed with the same cutting tool 10, it has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0060] <Shape of the base layer> The thickness of the underlying layer 5 may be 0.1 μm or more and 1.0 μm or less. Thereby, the cutting tool 1 can have a longer tool life, particularly even in interrupted turning of cast iron. The lower limit of the thickness of the underlying layer 5 may be 0.1 μm or more, may be 0.2 μm or more, or may be 0.3 μm or more. The upper limit of the thickness of the underlying layer 5 may be 1.0 μm or less, may be 0.9 μm or less, or may be 0.8 μm or less. The thickness of the underlying layer 5 may be 0.2 μm or more and 0.9 μm or less, or may be 0.3 μm or more and 0.8 μm or less.

[0061] ≪Other Layers≫ The coating 2 may further include other layers. When the coating 2 includes the second layer 4 and the underlying layer 5, examples of the other layers include a "first intermediate layer located between the first layer 3 and the second layer 4" (not shown), a "second intermediate layer located between the second layer 4 and the underlying layer 5" (not shown), and a "surface layer located on the surface of the coating 2" (not shown). Further, when the coating 2 includes the second layer 4 and does not include the underlying layer 5, examples of the other layers include a "first intermediate layer located between the first layer 3 and the second layer 4" (not shown) and a "surface layer located on the surface of the coating 2" (not shown). Further, when the coating 2 includes the underlying layer 5 and does not include the second layer 4, examples of the other layers include a "third intermediate layer located between the first layer 3 and the underlying layer 5" (not shown) and a "surface layer located on the surface of the coating 2" (not shown).

[0062] [Embodiment 2: Manufacturing Method of Cutting Tool] The manufacturing method of the cutting tool of this embodiment will be described with reference to FIG. 4. FIG. 4 is a schematic cross-sectional view of an example of a CVD apparatus used for manufacturing the cutting tool of this embodiment.

[0063] The manufacturing method of the cutting tool according to this embodiment is the manufacturing method of the cutting tool described in Embodiment 1, and includes a first step of preparing a base material and a second step of forming a coating on the base material. The first step includes a first A step of obtaining a mixed powder by mixing tungsten carbide powder (WC powder) and cobalt powder (Co powder), a first B step of obtaining a formed body by drying the mixed powder and then forming it into a predetermined shape, a first C step of obtaining a base material intermediate by sintering the formed body, and a first D step of obtaining a base material by performing surface treatment on the base material intermediate, in this order. The second step includes a second A step of forming a first layer by CVD method. The second step may further include a second B step of forming a second layer by CVD method, a second C step of forming an underlayer by CVD method, or both. When the second step further includes the second B step and does not include the second C step, the second step includes the second B step and the second A step in this order. When the second step further includes the second C step and does not include the second B step, the second step includes the second C step and the second A step in this order. When the second step further includes the second B step and the second C step, the second step includes the second C step, the second B step, and the second A step in this order. Details of each step will be described below.

[0064] <<First Step>> <<First A Step>> In the first A step, a mixed powder is obtained by mixing WC powder and Co powder. For mixing, for example, a ball mill or the like can be used. In the first A step, in addition to WC powder and Co powder, other materials can be mixed. Examples of the other materials include TiC, TiCN, NbC, etc. The composition of the mixed powder can be, for example, as follows with respect to 100 parts by mass of the mixed powder. (Composition of the mixed powder) WC powder: 88 parts by mass or more and 95 parts by mass or less Co powder: 5 parts by mass or more and 12 parts by mass or less

[0065] <<First B Step>> In the 1B process, after drying the above mixed powder, a molded body is obtained by molding it into a predetermined shape. Examples of the shape include the shapes of "SEET13T3AGSN-G" and "CNMG120408N-GZ" manufactured by Sumitomo Electric Hardmetal Corporation.

[0066] <1C Process> In the 1C process, a base material intermediate is obtained by sintering the above molded body. More specifically, the sintering can be carried out under the following conditions. (Sintering Conditions) Sintering temperature: 1300 °C or higher and 1500 °C or lower Sintering time: 40 minutes or longer and 90 minutes or shorter

[0067] <1D Process> In the 1D process, a base material is obtained by performing surface treatment on the base material intermediate. More specifically, the surface treatment is carried out under the following conditions. As a result, "the ratio of the total length of the line segments located on the straight line and the bonding phase to the length of the straight line included in the virtual surface VS2" and "the roughness Rz of the surface of the base material in contact with the coating JIS " can be set within a desired range. (Surface Treatment Conditions) Method: Brush polishing Polishing time: 60 seconds or longer and 240 seconds or shorter

[0068] When the 2B process described later is not executed, by setting the method of the 1D process to brush polishing, the ratio of the voids in the second region can be set within a desired range. On the other hand, when the 2B process described later is executed, by setting the method of the 1D process to brush polishing and setting the temperature in the reaction vessel 32 in the 2B process to less than 900 °C, the ratio of the voids in the second region can be set within a desired range.

[0069] The material of the brush used for brush polishing can be, for example, diamond abrasive grains or ceramic abrasive grains. The abrasive grain size of the diamond abrasive grains and the abrasive grain size of the ceramic abrasive grains can be, for example, 10 μm or larger and 100 μm or smaller.

[0070] <<Second Step>> In the second step, a coating is formed on the above substrate to obtain a cutting tool. The formation of the coating is performed, for example, using the CVD apparatus shown in FIG. 4. The CVD apparatus 30 includes a plurality of substrate setting jigs 31 for holding the substrate 1 and a reaction vessel 32 made of heat-resistant alloy steel that covers the substrate setting jig 31. Further, a temperature control device 33 for controlling the temperature inside the reaction vessel 32 is provided around the reaction vessel 32. The reaction vessel 32 is provided with a gas introduction pipe 35 having a gas inlet 34. The gas introduction pipe 35 extends in the vertical direction in the internal space of the reaction vessel 32 where the substrate setting jig 31 is disposed and is rotatably disposed about the vertical direction as an axis, and a plurality of ejection holes (through holes 36) for ejecting gas into the reaction vessel 32 are provided. Using this CVD apparatus 30, the first layer, the second layer, and the underlying layer that constitute the above coating can be formed as follows.

[0071] When the coating includes the "other layer" described in Embodiment 1, the second step may further include a step of forming the "other layer". The "other layer" can be formed by a conventionally known method.

[0072] <<Second A Step: Step of Forming the First Layer by CVD Method>> In the second A step, the first layer is formed by the CVD method. More specifically, in the substrate setting jig 31 on which the substrate 10 is disposed, while controlling the temperature and pressure inside the reaction vessel 32 within a predetermined range, the reaction gas for the first layer is introduced into the reaction vessel 32 from the gas introduction pipe 35. Thereby, the first layer is formed on the substrate 10.

[0073] As the reaction gas for the first layer, a mixed gas of AlCl3, TiCl4, CO2, H2S, NH3, HCl, N2, and H2 can be used.

[0074] The content of AlCl3 in the mixed gas may be 0.7% by volume or more and 2.0% by volume or less. The content of TiCl4 in the mixed gas may be 0% by volume or more and 0.2% by volume or less. The content of CO2 in the mixed gas may be 0% by volume or more and 4.5% by volume or less. The content of H2S in the mixed gas may be 0% by volume or more and 0.2% by volume or less. The content of NH3 in the mixed gas may be 0% by volume or more and 2.8% by volume or less. The content of HCl in the mixed gas may be 0.2% by volume or more and 3.5% by volume or less. The content of N2 in the mixed gas may be 0% by volume or more and 35% by volume or less. The content of H2 in the mixed gas may be 60% by volume or more and 95% by volume or less.

[0075] The flow rate of the reaction gas for the first layer (in other words, the total gas flow rate for the first layer) may be 50 L / min or more and 70 L / min or less.

[0076] The temperature inside the reaction vessel 32 is controlled to be 850 °C or more and 1000 °C or less. The pressure inside the reaction vessel 32 may be controlled to be 3.0 kPa or more and 7.0 kPa or less. Note that the gas introduction pipe 35 may be rotated during gas introduction.

[0077] Regarding the above manufacturing method, by controlling each condition of the CVD method, the aspect of the first layer changes. For example, by adjusting the film formation time, the thickness of the first layer is controlled.

[0078] <Second Step B: Step of forming the second layer by CVD method> In the second step B, the second layer is formed by CVD method. More specifically, before the above second step A is executed, in the substrate set jig 31 on which the substrate 10 is disposed, while controlling the temperature and pressure inside the reaction vessel 32 within a predetermined range, the reaction gas for the second layer is introduced from the gas introduction pipe 35 into the reaction vessel 32. Thereby, the second layer is formed.

[0079] As the reaction gas for the second layer, a mixed gas of TiCl4, CH3CN, and H2 can be used.

[0080] The content of TiCl4 in the mixed gas may be 1.0% by volume or more and 3.0% by volume or less. The content of CH3CN in the mixed gas may be 0.5% by volume or more and 1.0% by volume or less. The content of H2 in the mixed gas may be 96% by volume or more and 98.5% by volume or less.

[0081] The flow rate of the reaction gas for the second layer (in other words, the total gas flow rate for the second layer) may be 50 L / min or more and 60 L / min or less.

[0082] The temperature inside the reaction vessel 32 may be controlled to be 800 °C or more and 860 °C or less, and the pressure inside the reaction vessel 32 may be controlled to be 8 kPa or more and 10 kPa or less. In addition, the gas introduction pipe 35 may be rotated during gas introduction.

[0083] Regarding the above manufacturing method, by controlling each condition of the CVD method, the aspect of the second layer changes. For example, by adjusting the film formation time, the thickness of the second layer is controlled.

[0084] <Second C step: Step of forming an underlayer by CVD method> In the second C step, an underlayer is formed by CVD method. More specifically, when the second step includes the second B step, before the above second B step is executed, in the substrate set jig 31 on which the substrate 10 is disposed, while controlling the temperature and pressure inside the reaction vessel 32 within a predetermined range, the reaction gas for the underlayer is introduced into the reaction vessel 32 from the gas introduction pipe 35. On the other hand, when the second step does not include the second B step, before the above second A step is executed, in the substrate set jig 31 on which the substrate 10 is disposed, while controlling the temperature and pressure inside the reaction vessel 32 within a predetermined range, the reaction gas for the underlayer is introduced into the reaction vessel 32 from the gas introduction pipe 35. Thereby, an underlayer is formed.

[0085] As the raw material gas for the underlayer, a mixed gas of TiCl4, N2, and H2 can be used.

[0086] The content of TiCl4 in the mixed gas may be 1% by volume or more and 3% by volume or less. The content of N2 in the mixed gas may be 38% by volume or more and 42% by volume or less. The content of H2 in the mixed gas may be 55% by volume or more and 61% by volume or less.

[0087] The flow rate of the reaction gas for the underlayer (in other words, the total gas flow rate for the underlayer) may be 60 L / min or more and 70 L / min or less.

[0088] The temperature inside the reaction vessel 32 may be controlled to be 800 °C or more and 900 °C or less, and the pressure inside the reaction vessel 32 may be controlled to be 5 kPa or more and 10 kPa or less. In addition, when introducing the gas, the gas introduction pipe 35 may be rotated.

[0089] Regarding the above manufacturing method, by controlling each condition of the CVD method, the form of the underlayer changes. For example, by adjusting the film formation time, the thickness of the underlayer is controlled.

[0090] <Other processes> In addition to the above steps, the second step may include surface treatment steps such as surface grinding and shot blasting.

Examples

[0091] The present embodiment will be described in more detail by way of examples. However, the present embodiment is not limited by these examples.

[0092] ≪Manufacture of cutting tools≫ Cutting tools according to Samples 1 to 24 and 101 to 106 were manufactured as follows.

[0093] <First A step> Using a ball mill, "Uniform Grain Tungsten Carbide Powder" (trademark), which is WC powder manufactured by Allied Material Co., Ltd., and Co powder (average particle size: 2.0 μm) were mixed to obtain a mixed powder. At that time, WC powder and Co powder were used in the parts by mass described in Tables 1 and 2 with respect to 100 parts by mass of the mixed powder.

[0094] <Step 1B> After drying the above mixed powder under the conditions of 500°C for 30 minutes, a molded body was obtained by molding it into the shape of "CNMG120408N-GZ" manufactured by Sumitomo Electric Hardmetal Corporation.

[0095] <Step 1C> By sintering the above molded body under the conditions described in Table 1 and Table 2, a base material intermediate was obtained.

[0096] <Step 1D> A base material was obtained by performing surface treatment on the base material intermediate under the conditions described in Table 1 and Table 2. In the "Method" column of Table 1 and Table 2, when "Brush Polishing" is described, it means that "Brush Polishing" was performed using "Brush Wire" (manufactured by Toray Industries, Inc.). In the "Method" column of Table 1 and Table 2, when "Blast Polishing" is described, it means that "Blast Polishing" was performed using "Blast Media" (manufactured by Toray Industries, Inc.).

[0097] <Step 2C> For the base materials of Sample 1, 1-1, 2 to 23, and Samples 101 to 106, an underlayer was formed by CVD method under the conditions described in Table 3 and Table 4 to have the thickness described in Table 11 and Table 12. In all columns of the "Temperature [°C]", "Pressure [kPa]", "Total Gas Flow Rate [L / min]", and "Reaction Gas Composition" columns of Table 3 and Table 4, when "-" is described, it means that Step 2C was not performed.

[0098] <Step 2B> For the base layers of Samples 1, 1-1, 2, 3, 5 to 23, and Samples 101 to 103, the second layer was formed by CVD method under the conditions described in Tables 5 and 6 to have the thicknesses described in Tables 11 and 12. Also, for the base material of Sample 24, the second layer was formed by CVD method under the conditions described in Table 6 to have the thicknesses described in Tables 11 and 12. Note that when "-" is described in all columns of the "Temperature [°C]", "Pressure [kPa]", "Total gas flow rate [L / min]", and "Reaction gas composition" columns in Tables 5 and 6, it means that the second B process was not performed.

[0099] <Second A process> For the second layer of Samples 1, 1-1, 2, 3, 5 to 24, and Samples 101 to 103, the first layer was formed by CVD method under the conditions described in Tables 7 and 8 to have the thicknesses described in Tables 11 and 12. Also, for the base material of Sample 1-2, the first layer was formed by CVD method under the conditions described in Table 7 to have the thicknesses described in Tables 11 and 12. Further, for the base layers of Samples 4 and Samples 104 to 106, the first layer was formed by CVD method under the conditions described in Tables 7 and 8 to have the thicknesses described in Tables 11 and 12.

[0100] By the above procedure, cutting tools related to Samples 1 to 24, 101 to 106 were manufactured.

[0101]

Table 1

[0102]

Table 2

[0103]

Table 3

[0104]

Table 4

[0105]

Table 5

[0106]

Table 6

[0107]

Table 7

[0108]

Table 8

[0109]

Table 9

[0110]

Table 10

[0111]

Table 11

[0112]

Table 12

[0113] ≪Characteristics Evaluation of Substrate≫ <Composition of Hard Phase> For the cutting tools according to each sample, the composition of the hard phase was determined by the method described in Embodiment 1. The obtained results are described in the column of "Composition" in the column of "Hard Phase" in Table 9 and Table 10. When it is described as "WC particles" in the column of "Composition" in the column of "Hard Phase" in Table 9 and Table 10, it means that the hard phase consists of tungsten carbide particles.

[0114] <Content ratio of hard phase in substrate> For the cutting tools according to each sample, the content ratio of the hard phase in the substrate was determined by the method described in Embodiment 1. The obtained results are described in the column of "Content ratio [volume %]" in the column of "Hard phase" in Tables 9 and 10.

[0115] <Particle size of tungsten carbide particles> For the cutting tools according to each sample, the particle size of the tungsten carbide particles was determined by the method described in Embodiment 1. The obtained results are described in the column of "Particle size of WC particles [μm]" in Tables 9 and 10.

[0116] <Composition of binder phase> For the cutting tools according to each sample, the composition of the binder phase was determined by the method described in Embodiment 1. The obtained results are described in the column of "Composition" in the column of "Binder phase" in Tables 9 and 10. When it is described as "metal Co" in the column of "Composition" in the column of "Binder phase" in Tables 9 and 10, it means that the binder phase consists of metal cobalt.

[0117] <Content ratio of binder phase in substrate> For the cutting tools according to each sample, the content ratio of the binder phase in the substrate was determined by the method described in Embodiment 1. The obtained results are described in the column of "Content ratio [volume %]" in the column of "Binder phase" in Tables 9 and 10.

[0118] <Ratio occupied by L2 with respect to L1> For the cutting tools according to each sample, the "ratio occupied by the total length (L2) of the line segments located at the straight line and the binder phase with respect to the length (L1) of the straight line included in the virtual plane VS2" was determined by the method described in Embodiment 1. The obtained results are described in the column of "(L2 / L1)×100 [%]" in Tables 9 and 10.

[0119] <Ratio occupied by voids in the second region> For each cutting tool related to each sample, the ratio occupied by voids in the second region was determined by the method described in Embodiment 1. The obtained results are described in the columns of "Ratio of voids in the second region [volume %]" in Tables 9 and 10.

[0120] <Roughness Rz of the surface in contact with the coating of the substrate JIS > For each cutting tool related to each sample, the roughness Rz of the surface in contact with the coating of the substrate JIS was determined by the method described in Embodiment 1. The obtained results are described in the columns of "Roughness Rz JIS [μm]" in Tables 9 and 10.

[0121] ≪Evaluation of coating properties≫ <Composition of the underlayer> For each cutting tool related to each sample, the composition of the underlayer was determined by the method described in Embodiment 1. The obtained results are described in the columns of "Composition" in the column of "Underlayer" in Tables 11 and 12. When "TiN" is described in the column of "Composition" in the column of "Underlayer" in Tables 11 and 12, it means that the underlayer is made of titanium nitride. When "-" is described in the column of "Composition" in the column of "Underlayer" in Tables 11 and 12, it means that there is no underlayer.

[0122] <Thickness of the underlayer> For each cutting tool related to each sample, the thickness of the underlayer was determined by the method described in Embodiment 1. The obtained results are described in the columns of "Thickness [μm]" in the column of "Underlayer" in Tables 11 and 12.

[0123] <Composition of the second layer> For each cutting tool related to each sample, the composition of the second layer was determined by the method described in Embodiment 1. The obtained results are described in the columns of "Composition" in the column of "Second layer" in Tables 11 and 12. When "TiCN" is described in the column of "Composition" in the column of "Second layer" in Tables 11 and 12, it means that the second layer is made of titanium carbonitride. When "-" is described in the column of "Composition" in the column of "Second layer" in Tables 11 and 12, it means that there is no second layer.

[0124] <Thickness of the second layer> For the cutting tools according to each sample, the thickness of the second layer was determined by the method described in Embodiment 1. The obtained results are recorded in the column of "Thickness [μm]" in the "Second layer" column of Tables 11 and 12.

[0125] <Composition of the first layer> For the cutting tools according to each sample, the composition of the first layer was determined by the method described in Embodiment 1. The obtained results are recorded in the column of "Composition" in the "First layer" column of Tables 11 and 12. When "Al2O3" is described in the column of "Composition" in the "First layer" column of Tables 11 and 12, it means that the first layer is made of aluminum oxide. When "AlTiN" is described in the column of "Composition" in the "First layer" column of Tables 11 and 12, it means that the first layer is made of aluminum titanium nitride.

[0126] <Thickness of the first layer> For the cutting tools according to each sample, the thickness of the first layer was determined by the method described in Embodiment 1. The obtained results are recorded in the column of "Thickness [μm]" in the "First layer" column of Tables 11 and 12.

[0127] <Thickness of the coating> For the cutting tools according to each sample, the thickness of the coating was determined by the method described in Embodiment 1. The obtained results are recorded in the column of "Thickness [μm]" in the "Overall" column of Tables 11 and 12.

[0128] ≪Cutting test≫ Using the cutting tools according to each sample, a cutting test was performed under the following cutting conditions. The time when wear and chipping were combined and damage progressed, and the maximum flank wear amount Vbmax [mm] of the cutting edge portion of the cutting tool exceeded 0.3 mm was measured as the tool life. The obtained results are recorded in the column of "Tool life [minutes]" in Tables 11 and 12. (Cutting conditions) Workpiece material: FCD700 (grooved round bar) Machining: Grooved round bar outer diameter turning Cutting speed: 150 m / min Feed rate: 0.2 mm / rev Cutting fluid: Water-soluble cutting oil The above cutting conditions correspond to the cutting conditions for interrupted turning of cast iron.

[0129] The cutting tools related to Samples 1 to 24 correspond to the examples. The cutting tools related to Samples 101 to 106 correspond to the comparative examples. From the results in Tables 11 and 12, it was found that the cutting tools related to Samples 1 to 24 have a longer tool life even in the interrupted turning of cast iron compared to the cutting tools related to Samples 101 to 106.

[0130] From the above, it was found that the cutting tools related to Samples 1 to 24 have a longer tool life even in the interrupted turning of cast iron.

[0131] Although the embodiments and examples of the present disclosure have been described as above, it has been planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples or to variously modify them.

[0132] The embodiments and examples disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above-described embodiments and examples but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0133] 1 Substrate, 2 Coating, 3 First layer, 4 Second layer, 5 Underlayer, 10 Cutting tool, 30 CVD apparatus, 31 Substrate setting jig, 32 Reaction vessel, 33 Temperature control device, 34 Gas inlet, 35 Gas inlet pipe, 36 Through hole

Claims

1. 1. A cutting tool comprising a substrate and a coating disposed on the substrate, The coating comprises a first layer, The substrate comprises a hard phase and a binder phase, the hard phase consists of tungsten carbide particles, the binder phase is made of metallic cobalt; the first layer is made of aluminum oxide or titanium aluminum nitride; The substrate has a first region, the first region is a region sandwiched between the interface between the substrate and the coating and a virtual plane VS1 that passes through a position 0.5 μm away from the interface toward the substrate and is parallel to the interface, a ratio of a total length of a line segment located in the straight line and the binder phase to a length of a straight line included in a virtual plane VS2 having an equal distance from the interface and an equal distance from the virtual plane VS1 is 50% or more and 90% or less, Roughness Rz of the surface of the substrate in contact with the coating ＪＩＳ is 1.0 μm or less.

2. the ratio of the sum of the lengths of the line segments located in the straight line and the binder phase to the length of a straight line included in an imaginary plane VS2 that is equidistant from the interface and from the imaginary plane VS1 is measured on a cross section along a normal direction of the interface between the substrate and the coating, Roughness Rz of the surface of the substrate in contact with the coating ＪＩＳ The cutting tool according to claim 1 , wherein the thickness of the coating is measured in the cross section along the normal direction of the interface between the substrate and the coating in accordance with JIS B0601:2001.

3. The substrate has a second region, the second region is a region sandwiched between the interface between the substrate and the coating and a virtual plane VS3 that passes through a position 2.0 μm away from the interface toward the substrate and is parallel to the interface, The cutting tool according to claim 1 or 2, wherein a ratio of voids in the second region is 0 volume % or more and 1.5 volume % or less.

4. The cutting tool according to claim 3 , wherein the proportion of the voids in the second region is measured in a cross section taken along a normal direction of the interface between the substrate and the coating.

5. The coating further comprises a second layer, the first layer is disposed on the second layer; The cutting tool according to claim 1 , wherein the second layer is made of titanium carbonitride.

6. The cutting tool according to claim 5 , wherein the second layer has a thickness of more than 0 μm and not more than 10 μm.

7. The cutting tool according to claim 1 , wherein the first layer has a thickness of 2.0 μm or more and 10 μm or less.

8. The cutting tool according to claim 1 , wherein the tungsten carbide particles have a particle size of 0.3 μm or more and 3.0 μm or less.

9. The cutting tool according to claim 1 , wherein the substrate contains the binder phase in an amount of from 8.0 vol. % to 20 vol. %.

Images