Cutting tool

Abstract

A cutting tool according to the present invention includes a base material and a coating disposed on the base material. The coating includes a first layer, and the base material includes a hard phase and a bonded phase. The hard phase is made of tungsten carbide particles and the bonded phase is made of metallic cobalt. The first layer is made of aluminum oxide or titanium aluminum nitride. The base material has a first region. The first region is sandwiched between an interface between the base material and the coating and a virtual plane VS1 that passes through a position 0.5 μm from the interface toward the base material side and is parallel to the interface. The proportion of the total length of line segments located between a straight line, which is included on a virtual plane VS2 located an equal distance from the interface and from the virtual plane VS1, and the bonding phase, with respect to the length of the straight line is 50-90%, and the roughness RzJIS of the surface of the base material in contact with the coating is 1.0 μm or less.

Description

cutting tools

[0001] The present disclosure relates to cutting tools.

[0002] Conventionally, cutting tools including a substrate and a coating disposed on the substrate have been used in cutting processes (Patent Documents 1 to 3).

[0003] Japanese Patent Laid-Open No. 05-237707 Japanese Patent Laid-Open No. 2002-331403 Japanese Patent Laid-Open No. 2013-220521

[0004] A cutting tool according to the present disclosure is a cutting tool comprising a substrate and a coating disposed on the substrate, wherein the coating includes a first layer, wherein the substrate is composed of a hard phase and a binder phase, wherein 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, wherein the substrate has a first region, wherein the first region is a region sandwiched between an interface between the substrate and the coating and an imaginary plane VS1 that passes through a position 0.5 μm away from the interface toward the substrate and is parallel to the interface, and wherein the ratio of the total length of the straight line and the line segments located in the binder phase to the length of a straight line included in an imaginary plane VS2 that is the same distance from the interface and from the imaginary plane VS1 is 50% or more and 90% or less, and wherein the roughness Rz of the surface of the substrate in contact with the coating ＪＩＳ is 1.0 μm or less.

[0005] Fig. 1 is a schematic cross-sectional view illustrating one embodiment of the cutting tool of the present disclosure. Fig. 2 is a schematic cross-sectional view illustrating another embodiment of the cutting tool of the present disclosure. Fig. 3 is a schematic cross-sectional view illustrating still another embodiment of the cutting tool of the present disclosure. Fig. 4 is a schematic cross-sectional view of an example of a CVD (Chemical Vapor Deposition) apparatus used in manufacturing the cutting tool of the present disclosure.

[0006] [Problem to be Solved by the Present Disclosure] In recent years, there has been an increasing demand for improved tool life, particularly in the interrupted turning of cast iron. Key factors for further improving tool life in the interrupted turning of cast iron include "wear resistance" and "fracture resistance." To improve wear resistance, cutting tools have been used in the interrupted turning of cast iron, including a substrate and a coating disposed on the substrate, the coating including a first layer, the substrate comprising a hard phase and a binder phase, the hard phase comprising tungsten carbide particles, the binder phase comprising metallic cobalt, and the first layer comprising aluminum oxide or titanium aluminum nitride. However, such coatings tend to peel off easily, and therefore may not have sufficient "fracture resistance." Furthermore, there have been cases where wear is easily caused by minute damage resulting from insufficient "fracture resistance" (i.e., there have been cases where "wear resistance" is insufficient). For this reason, there is a demand for extending tool life, particularly in intermittent turning of cast iron, by combining excellent "wear resistance" and excellent "fracture resistance."

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

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

[0009] [Explanation of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be described. (1) A cutting tool of the present disclosure is a cutting tool comprising a substrate and a coating disposed on the substrate, wherein 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, and 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 an imaginary plane VS1 that passes through a position 0.5 μm away from the interface toward the substrate and is parallel to the interface, the ratio of the total length of the straight line and the line segments located in the binder phase to the length of a straight line included in an imaginary plane VS2 that is the same distance from the interface and from the imaginary plane VS1 is 50% or more and 90% or less, and 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, a cutting tool having a long tool life can be provided, particularly in intermittent turning of cast iron.

[0011] (2) In the above (1), the ratio of the total length of the line segment located in the bonding phase to the length of a line included in an imaginary plane VS2 that is the same distance from the interface and the imaginary plane VS1 is measured on a cross section along the normal direction of the interface between the substrate and the coating, and is expressed as the roughness Rz of the surface of the substrate that is 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 substrate and the coating.

[0012] (3) In the above (1) or (2), the substrate may have a second region, the second region being a region sandwiched between the interface between the substrate and the coating and an imaginary plane VS3 that passes through a position 2.0 μm away from the interface toward the substrate and is parallel to the interface, and the proportion of voids in the second region may be 0% by volume or more and 1.5% by volume or less. This makes it possible to provide a cutting tool with a longer tool life, particularly in intermittent turning of cast iron.

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

[0014] (5) In any of the above (1) to (4), the coating may further include a second layer, the first layer being disposed on the second layer, and the second layer may be made of titanium carbonitride. This makes it possible to provide a cutting tool with a longer tool life, particularly in interrupted turning of cast iron.

[0015] (6) In the above (5), the thickness of the second layer may be greater than 0 μm and not greater than 10 μm, thereby providing a cutting tool having a longer tool life, particularly in intermittent turning of cast iron.

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

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

[0018] (9) In any one of the above (1) to (8), the substrate may contain 8.0 volume % or more and 20 volume % or less of the binder phase, thereby providing a cutting tool having a longer tool life, particularly in interrupted turning of cast iron.

[0019] [Details of the embodiment of the present disclosure] A specific example of a cutting tool according to one embodiment of the present disclosure (hereinafter also referred to as "the present embodiment") will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference symbols represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been changed as appropriate 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 a range (i.e., A or more and B or less), and when no unit is specified for A and a unit is specified only for B, the units of A and B are the same.

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

[0022] [Embodiment 1: Cutting Tool] A cutting tool according to one embodiment of the present disclosure will be described with reference to Figures 1 to 3. One embodiment of the present disclosure (hereinafter also referred to as "this embodiment") is a cutting tool 10 including a substrate 1 and a coating 2 disposed on the substrate 1, wherein the coating 2 includes a first layer 3, the substrate 1 is composed of a hard phase and a binder phase, the hard phase being composed of tungsten carbide particles, the binder phase being composed of metallic cobalt, and the first layer 3 being composed of aluminum oxide or titanium aluminum nitride, the substrate 1 having a first region R1, the first region R1 being a region sandwiched between an interface between the substrate 1 and the coating 2 and an imaginary plane VS1 that passes through a position 0.5 μm away from the interface towards the substrate 1 and is parallel to the interface, the ratio of the total length of the straight line and the line segment located in the binder phase (hereinafter also referred to as "L2") to the length of the straight line (hereinafter also referred to as "L1") included in the imaginary plane VS2 that is the same distance from the interface and the imaginary plane VS1 is 50% or more and 90% or less; and the roughness Rz of the surface of the substrate 1 that is 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 for this is presumed to be as follows.

[0024] (a) The substrate 1 has a first region R1, which is a region sandwiched between the interface between the substrate 1 and the coating 2 and an imaginary plane VS1 that passes through a position 0.5 μm away from the interface toward the substrate 1 and is parallel to the interface, and the ratio of the total length (L2) of the straight line and the line segment located in the binder phase to the length (L1) of the straight line included in the imaginary plane VS2 that is the same distance from the interface and the imaginary plane VS1 is 50% or more and 90% or less. This improves the adhesion between the substrate 1 and the coating 2, thereby improving "wear resistance" and "fracture resistance."

[0025] (b) Roughness Rz of the surface of the substrate 1 in contact with the coating 2 ＪＩＳis 1.0 μm or less. This makes it easier to form the coating 2 uniformly, which improves the strength of the coating 2 and thereby improves the "wear resistance" and "fracture resistance."

[0026] That is, according to the present disclosure, since the cutting tool 10 can have both excellent "wear resistance" and excellent "fracture resistance," it is possible to provide a cutting tool having a long tool life, particularly in intermittent turning of cast iron.

[0027] 1 to 3 , a cutting tool 10 according to an embodiment of the present disclosure includes a substrate 1 and a coating 2 disposed on the substrate 1. The coating 2 may cover the entire surface of the substrate 1, but it does not depart from the scope of this embodiment even if a portion of the substrate 1 is not covered with the coating 2 or if the configuration of the coating 2 is partially different. In cases where a portion of the substrate 1 is not covered with the coating 2, the coating 2 may be disposed so as to cover the surface of at least a portion of the substrate 1 that is involved in cutting. In this specification, the portion of the substrate 1 that is involved in cutting refers to a region of the substrate 1 that is surrounded by the cutting edge ridge and an imaginary surface that is, depending on the size and shape of the substrate 1, a distance from the cutting edge ridge toward the substrate 1 along a perpendicular to a tangent to the cutting edge ridge, of, for example, 5 mm, 3 mm, 2 mm, 1 mm, or 0.5 mm.

[0028] The cutting tool 10 of this embodiment can be suitably used as a cutting tool 10 such as a drill, an end mill, an indexable cutting tip for a drill, an indexable cutting tip for an end mill, an indexable cutting tip for a milling process, an indexable cutting tip for a turning process, a metal saw, a gear cutting tool, a reamer, a tap, etc.

[0029] <<Substrate>> 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 (e.g., carbides, nitrides, carbonitrides of Ti, Ta, Nb, etc., and mixtures thereof) may be included as long as the effects of the present disclosure are not impaired.

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

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

[0032] The "content of the hard phase in the substrate 1" and the "content of the binder phase in the substrate 1" are determined by the following method. First, a 5000x image of an arbitrary cross section of the substrate 1 is obtained using a scanning electron microscope (SEM). In the image, an arbitrary "10 μm × 10 μm rectangular field of view" is identified. Next, in the rectangular field of view, the area of ​​the hard phase and the area of ​​the binder phase are measured using image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ). Next, the ratio of the area of ​​the hard phase to the area of ​​the rectangular field of view is calculated as a percentage to determine the "content of the hard phase in the substrate 1." Furthermore, the ratio of the area of ​​the binder phase to the area of ​​the rectangular field of view is calculated as a percentage to determine the "content of the binder phase in the substrate 1." It has been confirmed that as long as the measurement is performed on the same substrate 1, there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0033] <Hard Phase> The hard phase is made of tungsten carbide particles. This provides the substrate 1 with an excellent balance of hardness and strength, particularly at high temperatures, and when used in a cutting tool 10, can contribute to extending the life of the cutting tool 10. Note that "made of tungsten carbide particles" here means that other metal elements, precipitates, etc. may be included as long as they do not impair the effects of the present disclosure. Examples of other metal elements include Ni, Cr, and Fe. Examples of precipitates include TiC, TiCN, and NbC.

[0034] In the cutting tool 10, the composition of the hard phase can be identified by performing a mapping analysis on a cross section of any substrate 1 using an energy dispersive X-ray analyzer (EDS) attached to a scanning electron microscope (SEM). It has been confirmed that, as long as measurements are performed on the same substrate 1, 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. This facilitates a better balance between hardness and toughness, and the cutting tool 1 has a longer tool life, particularly in intermittent turning of cast iron. The lower limit of the particle size of the tungsten carbide particles may be 0.3 μm or more, 0.5 μm or more, or 0.7 μm or more. The upper limit of the particle size of the tungsten carbide particles may be 3.0 μm or less, 2.6 μm or less, or 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 0.7 μm or more and 2.5 μm or less.

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

[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 contained as long as the effects of the present disclosure are not impaired. Examples of other metal elements include Ni, Cr, and Fe. Examples of precipitates include TiC, TiCN, and NbC.

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

[0039] <Roughness Rz of the surface of the substrate that comes into contact with the coating ＪＩＳ > Roughness Rz of the surface of the substrate 1 in contact with the coating 2 ＪＩＳ The roughness Rz of the surface of the substrate 1 in contact with the coating 2 is 1.0 μm or less. This makes it possible to improve "wear resistance" and "fracture resistance". ＪＩＳ The lower limit of the roughness Rz of the surface of the substrate 1 in contact with the coating 2 may be 0 μm or more, but from the viewpoint of manufacturing, it can be set to, for example, 0.1 μm or more, 0.2 μm or more, or 0.3 μm or more. ＪＩＳ The upper limit of the roughness Rz of the surface of the substrate 1 in contact with the coating 2 may be 0.9 μm or less, 0.8 μm or less, or 0.7 μm or less. ＪＩＳ may be 0 μm or more and 1.0 μm or less, 0 μm or more and 0.9 μm or less, or 0 μm or more and 0.8 μm or less.

[0040] Roughness Rz of the surface of the substrate 1 in contact with the coating 2 ＪＩＳ can be measured in accordance with JIS B0601:2001 on a cross section normal to the interface between the substrate 1 and the coating 2. More specifically, first, an image is obtained by capturing an image of a cross section normal to the interface between the substrate 1 and the coating 2 using an SEM at 1000x magnification. Next, in the image, an arbitrary 10 μm x 10 μm rectangular observation field containing the interface is identified at 10,000x magnification. In the observation field, the interface is assumed to pass through any pair of opposing two sides. Next, image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ) is used to extract interface contour information for the observation field, thereby identifying the "ten-point mean roughness of the interface" in the observation field. Next, in the above image, the "ten-point mean roughness of the interface" is identified for any other four observation fields. Next, the roughness Rz of the surface of the substrate 1 in contact with the coating 2 was calculated by calculating the average value of the "ten-point average roughness of the interface" in a total of five observation fields. ＪＩＳ Identify.

[0041] It has been confirmed that as long as measurements are made using the same cutting tool 10, there is no variation in the measurement results even if the measurement location is selected arbitrarily.

[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 toward the substrate 1 and is parallel to the interface.

[0043] The ratio of the sum (L2) of the lengths of the straight lines and the line segments located in the binder phase to the length (L1) of the straight lines included in the imaginary plane VS2, which are the same distance from the interface and the imaginary plane VS1, is 50% or more and 90% or less. This improves the "wear resistance" and "fracture resistance" of the cutting tool 1. The lower limit of this ratio may be 55% or more, 60% or more, or 65% or more. The upper limit of this ratio may be 85% or less, 80% or less, or 75% or less. The ratio may be 55% or more and 85% or less, 60% or more and 80% or less, or 65% or more and 75% or less. In FIG. 1 , the "distance between the interface between the substrate 1 and the coating 2 and the imaginary plane VS2" is denoted as D1. In FIG. 1 , the "distance between the imaginary plane VS2 and the imaginary plane VS1" is denoted as D2. "The distance from the interface and the distance from the virtual surface VS1 are equal" can be rephrased as "D1 and D2 are equal."

[0044] The ratio of the sum (L2) of the lengths of the line segments located in the bond phase and the line included in the imaginary plane VS2, which is the same distance from the interface as the imaginary plane VS1, to the length (L1) of the line included in the imaginary plane VS2, can be measured in a cross section along the normal direction of the interface between the substrate 1 and the coating 2. More specifically, first, an observation image of the cross section is taken at a magnification of 1000 times using a scanning electron microscope. Next, an arbitrary "20 μm × 20 μm rectangular field of view" is identified in the observation image. Here, the line passes through any pair of two opposing sides in the rectangular field of view. Next, L1 and L2 are measured for the line in the rectangular field of view using image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ). Next, the ratio of L2 to L1 is calculated as (L2 / L1)×100.

[0045] It has been confirmed that as long as measurements are made using the same cutting tool 10, there is no variation in the measurement results even if the measurement location is selected arbitrarily.

[0046] <Second Region> The substrate 1 has a second region R2, which is a region sandwiched between the interface between the substrate 1 and the coating 2 and an imaginary plane VS3 that passes through a position 2.0 μm away from the interface toward the substrate 1 and is parallel to the interface. The proportion of voids in the second region R2 may be 0 vol% or more and 1.5 vol% or less. This makes it easier to suppress a decrease in the strength of the substrate 1, so that the cutting tool 1 has a longer tool life, especially in intermittent turning of cast iron. The lower limit of the proportion may be 0 vol% or more, 0.2 vol% or more, or 0.3 vol% or more. The upper limit of the proportion may be 1.5 vol% or less, 1.3 vol% or less, or 1.1 vol% or less. The proportion may be 0.2 vol% or more and 1.3 vol% or less, or 0.3 vol% or more and 1.1 vol% or less.

[0047] The proportion of voids in the second region R2 can be measured in a cross section taken along the normal direction of the interface between the substrate 1 and the coating 2. More specifically, an image is first obtained by capturing an image of a cross section taken along the normal direction of the interface between the substrate 1 and the coating 2 using an SEM at 1000x magnification. Next, an arbitrary 10 μm x 10 μm rectangular observation field is identified in the image at 10,000x magnification. In the observation field, the interface is assumed to pass through any pair of two opposing sides. Next, image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ) is used to identify the area of ​​the "second region R2" and the area of ​​the "voids in the second region R2" in the observation field. Next, the ratio 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, for any other four observation fields in the image, the ratio 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 "ratio of the voids in the second region R2" is determined by calculating the average value of the ratios 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] It has been confirmed that as long as measurements are made using the same cutting tool 10, there is no variation in the measurement results even if the measurement location is selected arbitrarily.

[0049] <Coating> <Shape of 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 generated within the coating 2 during cutting, making it more likely to peel or break. 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 determined 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 cross section sample is observed at a magnification of 1000x, and the observation field is a rectangular field of 120 μm × 100 μm. The thickness width is measured at three points in one field of view, and the average value is taken as the "thickness." The same applies to the thickness of each layer described below unless otherwise specified.

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

[0052] <First Layer> <Composition of First Layer> The coating 2 includes a first layer 3. The first layer 3 is made of aluminum oxide or titanium aluminum nitride. This makes it possible to suppress a reaction between the cutting tool 10 and the workpiece. Note that the phrase "made of aluminum oxide or titanium aluminum nitride" here means that other components may be included as long as they do not impair the effects of the present disclosure. Examples of other components include C atoms, Cr atoms, etc.

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

[0054] <Shape of First Layer> The thickness of the first layer 3 may be 2.0 μm or more and 10 μm or less. This allows the effect of the coating 2 to 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 Second Layer> The coating 2 may further include a second layer 4, with the first layer 3 disposed on the second layer 4, and the second layer 4 may be made of titanium carbonitride. This allows the cutting tool 1 to have a longer tool life, particularly in intermittent turning of cast iron. Note that "made of titanium carbonitride" here means that other components may be included as long as they do not impair the effects of the present disclosure. Examples of other components include Si atoms.

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

[0057] <Shape of Second Layer> The thickness of the second layer 4 may be more than 0 μm and not more than 10 μm. This allows the cutting tool 1 to have a longer tool life, particularly in intermittent turning of cast iron. The lower limit of the thickness of the second layer 4 may be more than 0 μm, 1 μm or more, or 2 μm or more. The upper limit of the thickness of the second layer 4 may be 10 μm or less, 9 μm or less, or 8 μm or less. The thickness of the second layer 4 may be 1 μm or more and 9 μm or less, or 2 μm or more and 8 μm or less.

[0058] <<Base Layer>> <Composition of 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. This allows for a longer tool life, particularly in intermittent turning of cast iron. Note that when the coating 2 further includes a base layer 5 in contact with the substrate 1 and also includes a 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. When the coating 2 further includes a base layer 5 in contact with the substrate 1 and 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 contained as long as they do not impair the effects of the present disclosure. Examples of other components include oxygen atoms.

[0059] The composition of the underlayer 5 can be identified by performing point analysis on an arbitrary cross section using an EDS attached to an SEM. It has been confirmed that there is no variation in the measurement results even if the measurement points are arbitrarily selected, as long as the measurement is performed using the same cutting tool 10.

[0060] <Shape of the Base Layer> The thickness of the base layer 5 may be 0.1 μm or more and 1.0 μm or less. This allows the cutting tool 1 to have a longer tool life, particularly in intermittent turning of cast iron. The lower limit of the thickness of the base layer 5 may be 0.1 μm or more, 0.2 μm or more, or 0.3 μm or more. The upper limit of the thickness of the base layer 5 may be 1.0 μm or less, 0.9 μm or less, or 0.8 μm or less. The thickness of the base layer 5 may be 0.2 μm or more and 0.9 μm or less, or 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 base 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 base layer 5" (not shown), and a "surface layer located on the surface of the coating 2" (not shown). When the coating 2 includes the second layer 4 but does not include the base 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). When the coating 2 includes the base layer 5 but 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 base layer 5" (not shown) and a "surface layer located on the surface of the coating 2" (not shown).

[0062] [Embodiment 2: Method for manufacturing a cutting tool] A method for manufacturing a 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 in manufacturing the cutting tool of this embodiment.

[0063] The cutting tool manufacturing method of this embodiment is the same as the cutting tool manufacturing method of the first embodiment, but includes a first step of preparing a substrate and a second step of forming a coating on the substrate. The first step includes, in this order, step 1A of mixing tungsten carbide powder (WC powder) and cobalt powder (Co powder) to obtain a mixed powder, step 1B of drying the mixed powder and then molding it into a predetermined shape to obtain a green body, step 1C of sintering the green body to obtain a substrate intermediate, and step 1D of performing a surface treatment on the substrate intermediate to obtain a substrate. The second step includes step 2A of forming a first layer by a CVD method. The second step may further include step 2B of forming a second layer by a CVD method, step 2C of forming a base layer by a CVD method, or both. When the second step further includes step 2B but does not include step 2C, the second step includes step 2B and step 2A, in this order. When the second step further includes step 2C but does not include step 2B, the second step includes step 2C and step 2A in this order. When the second step further includes step 2B and step 2C, the second step includes step 2C, step 2B, and step 2A in this order. Details of each step are described below.

[0064] <<Step 1>> <Step 1A> In Step 1A, a mixed powder is obtained by mixing WC powder and Co powder. For example, a ball mill or the like can be used for mixing. In Step 1A, other materials can be mixed in addition to the WC powder and Co powder. Examples of such other materials include TiC, TiCN, and NbC. The composition of the mixed powder can be, for example, as follows, relative to 100 parts by mass of the mixed powder. (Composition of 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] In step 1B, the mixed powder is dried and then molded into a predetermined shape to obtain a molded body. Examples of the shape include the "SET13T3AGSN-G" and "CNMG120408N-GZ" shapes manufactured by Sumitomo Electric Hardmetal Corp.

[0066] <Step 1C> In Step 1C, the above-mentioned compact is sintered to obtain a substrate intermediate. 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 higher and 90 minutes or lower

[0067] <Step 1D> In step 1D, a substrate is obtained by performing a surface treatment on the substrate intermediate. More specifically, the surface treatment is performed under the following conditions. This allows the ratio of the total length of the line segments located between the line and the bonding phase to the length of the line included in the imaginary plane VS2 to be calculated, and the roughness Rz of the surface of the substrate in contact with the coating to be calculated. ＪＩＳ " can be set within the desired range. (Conditions for surface treatment) Method: Brush polishing Polishing time: 60 seconds or more and 240 seconds or less

[0068] When the later-described step 2B is not performed, the proportion of voids in the second region can be set within a desired range by using brush polishing as the method for step 1D. On the other hand, when the later-described step 2B is performed, the later-described step 2B can be performed by using brush polishing as the method for step 1D and setting the temperature inside the reaction vessel 32 in step 2B to less than 900°C, thereby setting the proportion of voids in the second region 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 more and 100 μm or less.

[0070] <<Second Step>> In the second step, a coating is formed on the substrate to obtain a cutting tool. The coating is formed using, for example, a CVD apparatus as shown in FIG. 4 . The CVD apparatus 30 includes a plurality of substrate setting jigs 31 for holding the substrate 1 and a heat-resistant alloy steel reaction vessel 32 that encases the substrate setting jigs 31. A temperature control device 33 is provided around the reaction vessel 32 to control the temperature inside the reaction vessel 32. The reaction vessel 32 is provided with a gas introduction pipe 35 having a gas introduction port 34. The gas introduction pipe 35 extends vertically within the internal space of the reaction vessel 32 in which the substrate setting jigs 31 are placed, and is rotatable about the vertical axis. The gas introduction pipe 35 is also provided with a plurality of injection holes (through holes 36) for injecting gas into the reaction vessel 32. Using this CVD apparatus 30, the first layer, second layer, and underlayer that constitute the coating can be formed as follows.

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

[0072] <Step 2A: Step of forming first layer by CVD method> In step 2A, the first layer is formed by CVD method. More specifically, in the substrate setting jig 31 in which the substrate 10 is placed, a reaction gas for the first layer is introduced into the reaction vessel 32 from the gas introduction pipe 35 while controlling the temperature and pressure inside the reaction vessel 32 within predetermined ranges. In this way, the first layer is formed on the substrate 10.

[0073] The reactive gas for the first layer is AlCl ３ , TiCl ４ , CO ２ , H ２ S., N.H. ３ , HCl, N ２ , and H ２ A mixture of the following gases can be used.

[0074] AlCl in mixed gas ３ The content of TiCl in the mixed gas may be 0.7% by volume or more and 2.0% by volume or less. ４The content of CO in the mixed gas may be 0% by volume or more and 0.2% by volume or less. ２ The content of H in the mixed gas may be 0% by volume or more and 4.5% by volume or less. ２ The content of S may be 0% by volume or more and 0.2% by volume or less. ３ The content of HCl in the mixed gas may be 0% by volume or more and 2.8% by volume or less. The content of N in the mixed gas may be 0.2% by volume or more and 3.5% by volume or less. ２ The content of H in the mixed gas may be 0% by volume or more and 35% by volume or less. ２ The content may be 60% by volume or more and 95% by volume or less.

[0075] The flow rate of the reactant 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 higher and 1000° C. or lower. The pressure inside the reaction vessel 32 may be controlled to be 3.0 kPa or higher and 7.0 kPa or lower. The gas introduction pipe 35 may be rotated when introducing the gas.

[0077] In the above manufacturing method, the state of the first layer can be changed by controlling the conditions of the CVD method, for example, by adjusting the film formation time, the thickness of the first layer can be controlled.

[0078] <Step 2B: Step of forming a second layer by CVD method> In step 2B, the second layer is formed by CVD method. More specifically, before step 2A is performed, in the substrate setting jig 31 in which the substrate 10 is placed, a reaction gas for the second layer is introduced into the reaction vessel 32 from the gas introduction pipe 35 while controlling the temperature and pressure in the reaction vessel 32 within predetermined ranges. In this way, the second layer is formed.

[0079] The reactive gas for the second layer is TiCl ４ , C.H. ３ CN, and H ２ A mixture of the following gases can be used.

[0080] TiCl in mixed gas ４The content of CH in the mixed gas may be 1.0% by volume or more and 3.0% by volume or less. ３ The content of CN may be 0.5% by volume or more and 1.0% by volume or less. ２ The content 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 higher and 860° C. or lower, and the pressure inside the reaction vessel 32 may be controlled to be 8 kPa or higher and 10 kPa or lower. Note that the gas introduction pipe 35 may be rotated when introducing the gas.

[0083] In the above manufacturing method, the state of the second layer can be changed by controlling the conditions of the CVD method, for example, by adjusting the film formation time, the thickness of the second layer can be controlled.

[0084] <Process 2C: Process for forming an underlayer by CVD method> In process 2C, an underlayer is formed by CVD method. More specifically, if process 2 includes process 2B, before process 2B is performed, in the substrate setting jig 31 in which the substrate 10 is placed, a reactive gas for the underlayer is introduced into the reaction vessel 32 from the gas inlet pipe 35 while controlling the temperature and pressure in the reaction vessel 32 within a predetermined range. On the other hand, if process 2 does not include process 2B, before process 2A is performed, in the substrate setting jig 31 in which the substrate 10 is placed, a reactive gas for the underlayer is introduced into the reaction vessel 32 from the gas inlet pipe 35 while controlling the temperature and pressure in the reaction vessel 32 within a predetermined range. In this way, the underlayer is formed.

[0085] The source gas for the underlayer is TiCl ４ , N ２ , and H ２ A mixture of the following gases can be used.

[0086] TiCl in mixed gas ４ The content of N in the mixed gas may be 1% by volume or more and 3% by volume or less. ２The content of H in the mixed gas may be 38% by volume or more and 42% by volume or less. ２ The content 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 higher and 900° C. or lower, and the pressure inside the reaction vessel 32 may be controlled to be 5 kPa or higher and 10 kPa or lower. Note that the gas introduction pipe 35 may be rotated when introducing the gas.

[0089] In the above manufacturing method, the state of the underlayer can be changed by controlling the various conditions of the CVD method, for example, the thickness of the underlayer can be controlled by adjusting the deposition time.

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

[0091] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0092] <<Preparation of Cutting Tools>> Cutting tools according to Samples 1 to 24 and 101 to 106 were prepared as follows.

[0093] <Step 1A> A mixed powder was obtained by mixing "Uniform-Grained Tungsten Carbide Powder" (trademark), a WC powder manufactured by A.L.M.T. Corp., with Co powder (average particle size: 2.0 μm) using a ball mill. The WC powder and Co powder were used in the amounts shown in Tables 1 and 2 relative to 100 parts by mass of the mixed powder.

[0094] <Step 1B> The mixed powder was dried at 500° C. for 30 minutes, and then molded into the shape of "CNMG120408N-GZ" manufactured by Sumitomo Electric Hardmetal Corp. to obtain a molded body.

[0095] <Step 1C> The above-mentioned compact was sintered under the conditions shown in Tables 1 and 2 to obtain a base material intermediate.

[0096] <Step 1D> Substrates were obtained by performing a surface treatment on the substrate intermediate under the conditions described in Tables 1 and 2. In the "Processing Method" column of Tables 1 and 2, when "brush polishing" is described, it means that "brush polishing" was performed using a "brush wire" (manufactured by Toray Industries, Inc.). In the "Processing Method" column of Tables 1 and 2, when "blast polishing" is described, it means that "blast polishing" was performed using a "blast media" (manufactured by Toray Industries, Inc.).

[0097] <Step 2C> Undercoating layers were formed by CVD on the substrates of Samples 1, 1-1, 2 to 23, and Samples 101 to 106 under the conditions shown in Tables 3 and 4, to thicknesses shown in Tables 11 and 12. Note that if "-" is entered in any of the following columns in Tables 3 and 4: "Temperature [°C]," "Pressure [kPa]," "Total gas flow rate [L / min]," and "Reaction gas composition," this means that Step 2C was not performed.

[0098] <Step 2B> A second layer was formed by CVD on the underlayers of Samples 1, 1-1, 2, 3, 5 to 23, and Samples 101 to 103 under the conditions set forth in Tables 5 and 6 to a thickness set forth in Tables 11 and 12. A second layer was formed by CVD on the substrate of Sample 24 under the conditions set forth in Table 6 to a thickness set forth in Tables 11 and 12. Note that if "-" is entered in any of the following columns in Tables 5 and 6: "Temperature [°C]," "Pressure [kPa]," "Total Gas Flow Rate [L / min]," and "Reaction Gas Composition," this means that Step 2B was not performed.

[0099] <Step 2A> For the second layers of Samples 1, 1-1, 2, 3, 5 to 24, and Samples 101 to 103, a first layer was formed by CVD under the conditions shown in Tables 7 and 8 to have the thicknesses shown in Tables 11 and 12. For the substrate of Sample 1-2, a first layer was formed by CVD under the conditions shown in Table 7 to have the thicknesses shown in Tables 11 and 12. For the underlayers of Sample 4 and Samples 104 to 106, a first layer was formed by CVD under the conditions shown in Tables 7 and 8 to have the thicknesses shown in Tables 11 and 12.

[0100] By the above procedure, cutting tools according to Samples 1 to 24 and 101 to 106 were produced.

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113] <Evaluation of substrate characteristics> <Composition of hard phase> For each cutting tool sample, the composition of the hard phase was determined by the method described in embodiment 1. The results obtained are shown in the "Composition" column of the "Hard phase" column in Tables 9 and 10. When "WC particles" is listed in the "Composition" column of the "Hard phase" column in Tables 9 and 10, it means that the hard phase is composed of tungsten carbide particles.

[0114] <Hard Phase Content in Substrate> For each cutting tool sample, the hard phase content in the substrate was determined by the method described in Embodiment 1. The results obtained are shown in the column "Content [vol %]" under "Hard Phase" in Tables 9 and 10.

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

[0116] <Composition of binder phase> The composition of the binder phase of each cutting tool sample was determined by the method described in embodiment 1. The results obtained are shown in the "Composition" column of the "Binder phase" column in Tables 9 and 10. When "Metallic Co" is written in the "Composition" column of the "Binder phase" column in Tables 9 and 10, it means that the binder phase is made of metallic cobalt.

[0117] <Binder Phase Content in Substrate> For each sample cutting tool, the binder phase content in the substrate was determined by the method described in Embodiment 1. The results obtained are shown in the "Binder Phase" column of Tables 9 and 10 under "Content [vol %]."

[0118] <Proportion of L2 to L1> For the cutting tools of each sample, the "proportion of the total length (L2) of the straight line included in the imaginary plane VS2 and the line segments located in the binder phase to the length (L1) of the straight line" was determined by the method described in embodiment 1. The obtained results are shown in the "(L2 / L1) × 100 [%]" column in Tables 9 and 10.

[0119] <Proportion of voids in second region> For each sample cutting tool, the proportion of voids in the second region was determined by the method described in embodiment 1. The results obtained are shown in the column "Proportion of voids in second region [volume %]" in Tables 9 and 10.

[0120] <Roughness Rz of the surface of the substrate that comes into contact with the coating ＪＩＳ For each sample cutting tool, the roughness Rz of the surface of the substrate in contact with the coating ＪＩＳThe results are shown in Tables 9 and 10 under the heading "Roughness Rz ＪＩＳ [μm]" column.

[0121] <<Evaluation of Coating Properties>> <Composition of Base Layer> For each cutting tool sample, the composition of the base layer was determined by the method described in embodiment 1. The results obtained are shown in the "Composition" column of the "Base Layer" column in Tables 11 and 12. When "TiN" is entered in the "Composition" column of the "Base Layer" column in Tables 11 and 12, it means that the base layer is made of titanium nitride. When "-" is entered in the "Composition" column of the "Base Layer" column in Tables 11 and 12, it means that no base layer is present.

[0122] <Thickness of Base Layer> For each sample cutting tool, the thickness of the base layer was determined by the method described in Embodiment 1. The results obtained are shown in the "Thickness [μm]" column of the "Base Layer" column in Tables 11 and 12.

[0123] <Composition of Second Layer> The composition of the second layer of each cutting tool sample was determined by the method described in Embodiment 1. The results obtained are shown in the "Composition" column of the "Second Layer" column in Tables 11 and 12. When "TiCN" is entered in the "Composition" column of the "Second Layer" column in Tables 11 and 12, it means that the second layer is made of titanium carbonitride. When "-" is entered in the "Composition" column of the "Second Layer" column in Tables 11 and 12, it means that the second layer is not present.

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

[0125] <Composition of First Layer> The composition of the first layer of each cutting tool sample was determined by the method described in Embodiment 1. The results are shown in the "Composition" column of the "First Layer" column in Tables 11 and 12. In Tables 11 and 12, the "Composition" column of the "First Layer" column indicates "Al ２ O ３" means that the first layer is made of aluminum oxide. When "AlTiN" is written in the "Composition" column of the "First Layer" column in Tables 11 and 12, it means that the first layer is made of titanium aluminum nitride.

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

[0127] <Coating Thickness> The coating thickness of each sample cutting tool was determined by the method described in Embodiment 1. The results obtained are shown in the "Thickness [μm]" column of the "Total" column in Tables 11 and 12.

[0128] <Cutting Test> Cutting tests were performed using the cutting tools of each sample under the following cutting conditions. The tool life was measured as the time until damage progressed due to a combination of wear and chipping, and the maximum flank wear volume Vbmax [mm] of the ridge line portion of the cutting tool exceeded 0.3 mm. The results are shown in the "Tool Life [min]" column of Tables 11 and 12. (Cutting Conditions) Workpiece: FCD700 (grooved round bar) Processing: External turning of grooved round bar 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 intermittent turning of cast iron.

[0129] The cutting tools of Samples 1 to 24 correspond to Examples. The cutting tools of Samples 101 to 106 correspond to Comparative Examples. The results in Tables 11 and 12 show that the cutting tools of Samples 1 to 24 have a longer tool life than the cutting tools of Samples 101 to 106, even in the interrupted turning of cast iron.

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

[0131] Although the embodiments and examples of the present disclosure have been described above, it is originally intended that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways.

[0132] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the embodiments and examples described above, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

[0133] REFERENCE SIGNS LIST 1 substrate, 2 coating, 3 first layer, 4 second layer, 5 undercoat layer, 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 or 2, 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 or 2, wherein the first layer has a thickness of 2.0 μm or more and 10 μm or less.

8. 3. 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 or 2, wherein the substrate contains the binder phase in an amount of 8.0 vol. % or more and 20 vol. % or less.