Coated tool and cutting tool

Abstract

A coated tool according to one non-limiting embodiment of the present disclosure comprises a base material and a coating layer positioned on the base material. The base material is a super-hard alloy having: a hard phase containing W and C; and a bonding phase containing Co. The base material has a surface region that is present from the surface towards an inner part. The surface region has an average Co content of 5.5-7 mass%, an average Vickers hardness of 1500-1600 Hv, and a standard deviation, which is an indicator of variation in the Co content, of 0.1-0.5 mass %.

Description

Coated tools and cutting tools CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2024-044852, filed on March 21, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to coated tools and cutting tools.

[0003] A coated tool used for cutting tools, etc., is known, for example, from Japanese Patent Laid-Open Publication No. 2015-157327 (Patent Document 1). The coated tool described in Patent Document 1 uses a WC-based cemented carbide as a tool substrate, which contains WC as a hard phase component and Co as a binder phase component. A Co-enriched region is formed in a depth region of 5 to 35 μm from the surface toward the interior of the tool substrate. The average Co content in the WC-based cemented carbide is 5 to 15 mass%.

[0004] A non-limiting aspect of the coated tool disclosed herein is a coated tool including a substrate and a coating layer disposed on the substrate. The substrate is a cemented carbide having a hard phase containing W and C and a binder phase containing Co. The substrate has a surface region extending from the surface toward the interior. The surface region has an average Co content of 5.5 to 7 mass %, an average Vickers hardness of 1500 to 1600 Hv, and a standard deviation, which is an index of variation in the Co content, of 0.1 to 0.5 mass %.

[0005] Fig. 2 is a perspective view showing a non-limiting one-sided coated tool of the present disclosure; Fig. 3 is a cross-sectional view perpendicular to the surface of the substrate in the coated tool shown in Fig. 1; Fig. 4 is a cross-sectional view showing the vicinity of the surface of a non-limiting one-sided coated tool of the present disclosure; Fig. 5 is a cross-sectional view showing the vicinity of the surface of a non-limiting one-sided coated tool of the present disclosure; Fig. 6 is a perspective view showing a non-limiting one-sided cutting tool of the present disclosure;

[0006] <Coated Tool> A non-limiting aspect of the coated tool 1 of the present disclosure will be described in detail below with reference to the drawings. However, for the sake of convenience, the drawings referred to below show only the main components necessary for explaining the embodiment in a simplified form. Therefore, the coated tool 1 may include any components not shown in the drawings referred to. Furthermore, the dimensions of the components in the drawings do not faithfully represent the actual dimensions of the components and the dimensional ratios of the components.

[0007] The coated tool 1 may comprise a substrate 3 and a coating layer 5 disposed on the substrate 3, as a non-limiting example shown in FIGS.

[0008] The substrate 3 may be a cemented carbide. In other words, the coated tool 1 may have a cemented carbide as the substrate 3. The cemented carbide may have a hard phase and a binder phase.

[0009] The hard phase may contain W (tungsten) and C (carbon). The hard phase may contain W and C as the main component. "Main component" means the component having the largest mass% value compared to other components. Specifically, the top two mass% values ​​of the components contained in the hard phase may be W and C. The hard phase may contain W and C in the form of WC.

[0010] The binder phase may contain Co (cobalt). The binder phase may contain Co as a main component. That is, Co may have the largest mass % value among the components contained in the binder phase. The binder phase may function as a phase that bonds adjacent hard phases.

[0011] The compositions of the hard phase and the binder phase may be measured, for example, by energy dispersive X-ray spectroscopy (EDS). The measurement may be performed using an EDS attached to an electron microscope. Examples of electron microscopes include a scanning electron microscope (SEM) and a transmission electron microscope (TEM).

[0012] Here, the substrate 3 may have a surface region 7, as shown in a non-limiting example in Figure 2. The surface region 7 may be present from the surface 9 of the substrate 3 toward the inside of the substrate 3.

[0013] The surface region 7 may have the following configuration: the average Co content may be 5.5 to 7 mass %, the average Vickers hardness (Hv) may be 1500 to 1600 Hv, and the standard deviation, which is an index of variation in the Co content, may be 0.1 to 0.5 mass %.

[0014] When the substrate 3 has the surface region 7 having such a configuration, the wear resistance and chipping resistance of the coated tool 1 are likely to be improved. Therefore, the coated tool 1 has high wear resistance and chipping resistance. This is presumably because the content of Co, which has the effect of improving the strength and toughness of the substrate 3, is uniform and has little variation in the surface region 7.

[0015] The average Co content and standard deviation may be values ​​measured at five locations using EDS. For example, when the thickness of the surface region 7 is 40 μm, the measurement locations may be set at 6, 14, 22, 30, and 38 μm from the surface 9 in a cross section perpendicular to the surface 9 of the substrate 3, and the average Co content and standard deviation in the surface region 7 may be calculated from the values ​​measured at these five locations. This point is the same when measuring a portion other than the surface region 7.

[0016] The average Vickers hardness is a value measured when the coated tool 1 is provided with the coating layer 5. Alternatively, the average Vickers hardness may be measured in accordance with JIS Z 2244:2009. Specific measurement conditions for the average Vickers hardness may be set, for example, as follows: Measurement device: INNOVATEST; Indentation strength: 10 kgf; Atmosphere: Air; Measurement temperature: 25°C; Number of measurements: 3; Other: Measurement is performed with the coating layer 5 positioned on the substrate 3. A cross section perpendicular to the surface 9 of the substrate 3 is mirror-polished to form a polished surface, and this polished surface serves as the measurement surface. For mirror polishing, a diamond paste with an average particle size of 1 to 3 μm manufactured by Tomei Diamond Co., Ltd. and olive oil manufactured by Yamakei Sangyo Co., Ltd., adjusted to a paste concentration of 20 to 30% by mass, are used. These points also apply when measuring other regions other than the surface region 7.

[0017] The surface region 7 may include the surface 9 of the substrate 3. The thickness of the surface region 7 may be 1 to 50 μm. The thickness of the surface region 7 may be measured by cross-sectional observation using an electron microscope.

[0018] The substrate 3 may further have an internal region 11, as shown in a non-limiting example in Fig. 2. The internal region 11 may extend from the surface region 7 toward the interior. The average Vickers hardness of the internal region 11 may be higher than that of the surface region 7. In such cases, the relatively soft surface region 7 tends to mitigate the impact with the workpiece during cutting. This tends to improve the wear resistance and chipping resistance of the coated tool 1.

[0019] The inner region 11 may have the following configuration: the average Co content may be 5.5 to 7 mass %, and the average Vickers hardness may be 1520 to 1620 Hv.

[0020] The internal region 11 may be in contact with the surface region 7. The thickness of the internal region 11 may be 50 to 150 μm. For example, the thickness of the internal region 11 may be evaluated assuming that it is 100 μm. The thickness of the internal region 11 may also be greater than the thickness of the surface region 7. In other words, the surface region 7 may be thinner than the internal region 11. For example, the thickness of the surface region 7 may be half or less of the thickness of the internal region 11. The thickness of the internal region 11 may be measured by cross-sectional observation using an electron microscope.

[0021] The coated tool 1 may further include an interface layer 13 at the interface between the substrate 3 and the coating layer 5, as a non-limiting example shown in FIG.

[0022] The interface layer 13 may contain Co. In this case, the adhesion between the substrate 3 and the coating layer 5 is likely to be improved.

[0023] The average Co content in the interface layer 13 may be 0.1 to 5 mass %.

[0024] The interface layer 13 may further contain C. The average content of C in the interface layer 13 may be 0.1 to 10 mass %.

[0025] In the interface layer 13, the content ratio of Co may decrease and the content ratio of C may increase with increasing distance from the base 3. In this case, the adhesion between the base 3 and the coating layer 5 is likely to be improved.

[0026] The interface layer 13 may contain Ti (titanium) as a main component. The composition of the interface layer 13 may be measured by, for example, EDS.

[0027] The interface layer 13 may have an average thickness of 0.1 to 1 μm. The thickness of the interface layer 13 may be measured by cross-sectional observation using an electron microscope. For example, the thickness may be measured at 10 or more measurement points at any position on the interface layer 13, and the average value may be calculated.

[0028] The inner region 11 may not contain β-phase particles made of WC and an iron-group metal. In this case, the wear resistance and chipping resistance of the coated tool 1 are likely to be improved. Examples of iron-group metals include Co and Ni (nickel). The absence of β-phase particles may be confirmed by, for example, EDS. Alternatively, the absence of β-phase particles may be confirmed by cross-sectional observation using an SEM. When an SEM is used for confirmation, it may be determined that the inner region 11 does not contain β-phase particles when the area ratio of β-phase particles is less than 5%.

[0029] The coating layer 5 may be located on the entire surface 9 of the substrate 3, or may be located on only a portion of the surface 9. In other words, the coating layer 5 may be located on at least a portion of the surface 9 of the substrate 3.

[0030] The coating layer 5 may be formed by a chemical vapor deposition (CVD) method. In other words, the coating layer 5 may be a CVD film. Note that the coating layer 5 may also be a physical vapor deposition (PVD) film formed by a PVD method.

[0031] The coating layer 5 may have a single layer structure or a multi-layer structure. Examples of the composition of the coating layer 5 include TiCN (titanium carbonitride), AlO (alumina), and TiN (titanium nitride).

[0032] 3, the coating layer 5 may have, in order from the substrate 3 side, a TiCN layer 15 and an Al2O3 layer 17. The Al2O3 layer 17 may be in contact with the TiCN layer 15.

[0033] 4, the coating layer 5 may have, from the substrate 3 side, a TiN layer 19, a TiCN layer 15, and an Al2O3 layer 17 in this order. The TiCN layer 15 may be in contact with the TiN layer 19. The Al2O3 layer 17 may be in contact with the TiCN layer 15.

[0034] The coating layer 5 is not limited to a specific thickness. For example, the TiCN layer 15 may have an average thickness of about 1 to 15 μm. The Al2O3 layer 17 may have an average thickness of about 1 to 15 μm. The TiN layer 19 may have an average thickness of about 0.1 to 5 μm. The thickness of the coating layer 5 may be measured by cross-sectional observation using an electron microscope. For example, the thickness may be measured at 10 or more measurement points at any position in each layer, and the average value may be calculated.

[0035] 1 shows a cutting insert as a non-limiting example of the coated tool 1. However, the form of the coated tool 1 is not limited to the cutting insert.

[0036] The coated tool 1 may have a first surface 21 (top surface), a second surface 23 (side surface) adjacent to the first surface 21, and a cutting edge 25 located at the intersection of the first surface 21 and the second surface 23.

[0037] The first surface 21 may be a rake face. The first surface 21 may be a rake face entirely, or only a portion of the first surface 21 may be a rake face. For example, a region of the first surface 21 along the cutting edge 25 may be a rake face.

[0038] The second surface 23 may be a flank. The second surface 23 may be a flank entirely, or only a portion thereof may be a flank. For example, a region of the second surface 23 along the cutting edge 25 may be a flank.

[0039] The cutting edge 25 may be located over the entire intersection of the first surface 21 and the second surface 23, or may be located over only a portion of this intersection. The cutting edge 25 can be used to cut a workpiece when a machined product is manufactured using the coated tool 1.

[0040] The coated tool 1 may have a through hole 27. The through hole 27 can be used to attach a screw, a clamp member, or the like when fixing the coated tool 1 to a holder. The through hole 27 may be formed from the first surface 21 to a surface (lower surface) located opposite the first surface 21, or may open in these surfaces. Note that there is no problem even if the through holes 27 are configured to open in mutually opposing regions of the second surface 23.

[0041] The coated tool 1 may have a rectangular plate shape. However, the shape of the coated tool 1 is not limited to a rectangular plate shape. For example, the first surface 21 may have a triangular, pentagonal, hexagonal, or circular shape.

[0042] The coated tool 1 is not limited to a specific size. For example, the length of one side of the first surface 21 may be set to about 3 to 20 mm. Furthermore, the height from the first surface 21 to the surface (lower surface) located on the opposite side of the first surface 21 may be set to about 5 to 20 mm.

[0043] <Method for Manufacturing a Coated Tool> Next, a method for manufacturing a non-limiting one-sided coated tool according to the present disclosure will be described.

[0044] When manufacturing a coated tool, a substrate may be prepared first. First, raw material powders such as WC powder, Co powder, Cr3C2 powder, and TaC powder may be prepared. The proportion of Co powder may be 5.5 to 7 mass %. The proportion of Cr3C2 powder may be 0.1 to 5 mass %. The proportion of TaC powder may be 0.1 to 5 mass %. The remainder may be WC powder.

[0045] The average particle size of the raw material powder may be appropriately selected from the range of 0.1 to 10 μm, and may be a value measured by a microtrack method.

[0046] The prepared raw material powders may be mixed and molded to obtain a molded body. Examples of molding methods include press molding, slip casting, extrusion molding, and cold isostatic pressing.

[0047] The resulting compact may be subjected to a binder removal treatment and then fired at a firing temperature of 1450 to 1600° C. for a firing time of 0.5 to 3 hours.

[0048] The firing may be performed in an atmosphere of a mixed gas of argon (Ar) gas and methane (CH4) gas. In this mixed gas, the argon gas may be present in a larger amount than the methane gas. When firing is performed in such a mixed gas atmosphere, the surface region having the above-described structure is easily formed. Also, the internal region having the above-described structure is easily formed. The mixed gas may be 60 to 99 volume % argon gas, with the remainder being methane gas.

[0049] After firing, the substrate may be cooled to obtain a substrate made of cemented carbide, and a coating layer may be formed on the substrate by CVD to obtain a coated tool.

[0050] The TiCN layer may be formed as follows. First, a mixed gas containing 0.1 to 10 volume percent titanium tetrachloride (TiCl) gas, 5 to 60 volume percent nitrogen (N), 0.1 to 3 volume percent acetonitrile (CHCN), and the remainder hydrogen (H) gas may be prepared as the reaction gas composition. This mixed gas may then be introduced into a chamber, and the temperature may be set to 800 to 1100°C and the pressure may be set to 5 to 30 kPa to form the TiCN layer.

[0051] The Al2O3 layer may be formed as follows. First, a mixed gas containing 0.5 to 5 volume percent aluminum trichloride (AlCl3) gas, 0.5 to 3.5 volume percent hydrogen chloride (HCl) gas, 0.5 to 5 volume percent carbon dioxide (CO2) gas, 0.5 volume percent or less hydrogen sulfide (HS) gas, and the remainder hydrogen (H2) gas may be prepared as the reaction gas composition. This mixed gas may then be introduced into a chamber, and the temperature may be set to 930 to 1010°C and the pressure may be set to 5 to 10 kPa to form the Al2O3 layer.

[0052] The TiN layer may be formed as follows. First, a mixed gas containing 0.1 to 10 volume percent titanium tetrachloride (TiCl4) gas, 10 to 60 volume percent nitrogen (N2) gas, and the remainder hydrogen (H2) gas may be prepared as the reaction gas composition. This mixed gas may then be introduced into a chamber, and the temperature may be set to 800 to 1010°C and the pressure may be set to 10 to 85 kPa to form the TiN layer.

[0053] Heat treatment may be carried out after forming the layer closest to the substrate (lowest layer). In this case, elements of the substrate and / or the lowest layer diffuse to the interface between the two, making it easier to form the interface layer having the above-mentioned structure. The conditions for the heat treatment may be set as follows, for example: Treatment temperature: 900 to 1000°C Treatment time: 0.1 to 2 hours

[0054] The above-described manufacturing method is merely an example of a method for manufacturing a coated tool, and it goes without saying that the coated tool is not limited to one manufactured by the above-described manufacturing method.

[0055] <Cutting Tool> Next, a non-limiting one-sided cutting tool 101 of the present disclosure will be described with reference to the drawings, taking as an example a case where the cutting tool 1 is provided with the above-described coated tool 1 .

[0056] 5 , the cutting tool 101 may include a holder 103 and a coated tool 1. The holder 103 may extend from a first end 103 a to a second end 103 b and may have a pocket 105 on the side of the first end 103 a. The coated tool 1 may be located in the pocket 105. When the cutting tool 101 includes the coated tool 1, stable cutting is possible due to the high wear resistance and chipping resistance of the coated tool 1.

[0057] The pocket 105 may be a portion to which the coated tool 1 is attached. The pocket 105 may be open at the outer peripheral surface of the holder 103 and at the end surface on the side of the first end 103a.

[0058] The coated tool 1 may be attached to the pocket 105 so that at least a part of the cutting edge 25 protrudes from the holder 103. Alternatively, the coated tool 1 may be attached to the pocket 105 by a screw 107. That is, the coated tool 1 may be attached to the pocket 105 by inserting the screw 107 into the through hole 27 of the coated tool 1 and inserting the tip of the screw 107 into a threaded hole formed in the pocket 105 to fix the screw 107 in the threaded hole. At this time, the lower surface of the coated tool 1 may be in direct contact with the pocket 105, or a sheet may be sandwiched between the coated tool 1 and the pocket 105.

[0059] Examples of materials for the holder 103 include steel and cast iron. When the material for the holder 103 is steel, the holder 103 has high toughness.

[0060] 5 illustrates a cutting tool 101 used for so-called turning. Examples of turning include inner diameter machining, outer diameter machining, and grooving. The cutting tool 101 (coated tool 1) is not limited to use for turning. For example, there is no problem in using the coated tool 1 for a cutting tool 101 used for milling.

[0061] The above has provided examples of the non-limiting one-sided coated tool 1 and cutting tool 101 of the present disclosure, but it goes without saying that the present disclosure is not limited to the above-mentioned embodiments and can be any as long as it does not deviate from the gist of the present disclosure.

[0062] For example, the coated tool 1 and cutting tool 101 may have the following configurations: [1] The coated tool is a coated tool including a substrate and a coating layer located on the substrate, wherein the substrate is a cemented carbide having a hard phase containing W and C and a binder phase containing Co, and has a surface region extending from the surface to the interior, wherein the surface region has an average Co content of 5.5 to 7 mass %, an average Vickers hardness of 1500 to 1600 Hv, and a standard deviation, which is an index of variation in the Co content, of 0.1 to 0.5 mass %. [2] In the coated tool of [1] above, the substrate may further have an internal region extending from the surface region to the interior, wherein the average Vickers hardness of the internal region is higher than that of the surface region. [3] In the coated tool of [2] above, the inner region may have an average Co content of 5.5 to 7 mass% and an average Vickers hardness of 1520 to 1620 Hv. [4] In any one of the coated tools of [1] to [3] above, the inner region may further include an interface layer at the interface between the substrate and the coating layer. [5] In the coated tool of [4] above, the interface layer may contain Co. [6] In the coated tool of [5] above, the average Co content in the interface layer may be 0.1 to 5 mass%. [7] In the coated tool of [5] or [6] above, the interface layer may further contain C, and the Co content ratio may decrease and the C content ratio may increase with increasing distance from the substrate. [8] In any one of the coated tool of [2] to [7] above, the inner region may be free of β-phase particles composed of WC and an iron-group metal. [9] In the coated tool of any one of [1] to [8] above, the coating layer may have, from the substrate side, a TiCN layer and an Al2O3 layer.

[10] In the coated tool of any one of [1] to [8] above, the coating layer may have, from the substrate side, a TiN layer, a TiCN layer, and an Al2O3 layer.

[11] A cutting tool may include a holder extending from a first end to a second end and having a pocket on the side of the first end, and the coated tool of any one of [1] to

[10] above, located in the pocket.

[0063] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0064] [Samples No. 1-4] <Preparation of Coated Tools> First, a substrate was prepared. Specifically, WC powder with an average particle size of 9 μm, Co powder with an average particle size of 1.5 μm, CrC powder with an average particle size of 1.5 μm, and TaC powder with an average particle size of 0.9 μm were prepared as raw material powders. The average particle sizes of the raw material powders were measured using the Microtrac method.

[0065] Next, 5.5% by mass of Co powder, 0.2% by mass of CrC powder, 0.3% by mass of TaC powder, and the remainder of WC powder were mixed and pressed into a cutting tool shape (CNMA120412) to obtain a green body. This green body was subjected to a binder removal treatment and then sintered.

[0066] The firing conditions were set as follows: firing temperature: 1450° C., firing time: 1 hour, and atmosphere: as shown in Table 1.

[0067] In the "Atmosphere" column of Table 1, "mixed gas" means that the compact was fired in a mixed gas. The mixed gas used contained more argon gas than methane gas. The mixed gas used in Samples No. 1 and 3 was the same mixed gas. "Argon" means that the compact was fired in argon gas. "Vacuum" means that the compact was fired in a vacuum.

[0068] After firing, the substrate was cooled to obtain a substrate made of cemented carbide. The composition of the cemented carbide in this substrate was measured by EDS. Specifically, cross-section observation was performed using an EDS attached to an SEM, with a magnification of 5,000 to 20,000 times, and measurements were taken at five locations to obtain an average value. Five elements were selected as the measurement elements for EDS: tungsten carbide, cobalt, chromium, tantalum, and carbon.

[0069] As a result of EDS measurement, all of the obtained cemented carbides had a hard phase and a binder phase. More specifically, all of the obtained cemented carbides had a hard phase containing WC as a main component and a binder phase containing Co as a main component.

[0070] Next, a coating layer was formed on the surface of the obtained substrate by a CVD method to obtain the coated tool samples shown in Table 1. The coating layers were formed in the order of a TiN layer, a TiCN layer, and an Al2O3 layer from the substrate side. The respective film formation conditions were as follows:

[0071] (TiN layer deposition conditions) First, a mixed gas consisting of 1 volume % titanium tetrachloride (TiCl4) gas, 38 volume % nitrogen (N2) gas, and the remainder hydrogen (H2) gas was prepared as the reaction gas composition. This mixed gas was then introduced into a chamber, and the temperature and pressure were set to 850°C and 18 kPa, respectively. The deposition time was set to 180 minutes.

[0072] (TiCN layer deposition conditions) First, a mixed gas containing 4 vol% titanium tetrachloride (TiCl4) gas, 23 vol% nitrogen (N2) gas, 0.4 vol% acetonitrile (CH3CN) gas, and the remainder hydrogen (H2) gas was prepared as the reaction gas composition. This mixed gas was then introduced into a chamber, and the temperature and pressure were set to 850°C and 9 kPa, respectively. The deposition time was set to 400 minutes.

[0073] (Al2O3 Layer Deposition Conditions) First, a mixed gas containing 3.7 vol% aluminum trichloride (AlCl3) gas, 0.7 vol% hydrogen chloride (HCl) gas, 4.3 vol% carbon dioxide (CO2) gas, 0.3 vol% hydrogen sulfide (HS) gas, and the remainder hydrogen (H2) gas was prepared as the reaction gas composition. This mixed gas was then introduced into a chamber, and the temperature and pressure were set to 950°C and 7.5 kPa, respectively. The deposition time was set to 380 minutes.

[0074] For Sample No. 1, the heat treatment was performed after forming the TiN layer, which was the layer closest to the substrate (the bottom layer). The heat treatment conditions were set as follows: Treatment temperature: 950°C Treatment time: 1 hour

[0075] In the obtained coated tool, the substrate had a surface region with a thickness of 40 μm and an inner region with a thickness of 100 μm. The average Co content and standard deviation for the surface region, and the average Co content for the inner region were measured according to the methods exemplified above. The average Vickers hardness in the surface region and the inner region were also measured according to the methods exemplified above. The measurement results are shown in Table 1. The average Co content is shown in the column "Average Co Amount (mass%)." The average Vickers hardness is shown in the column "Vickers Hardness (Hv)."

[0076] The coated tools thus obtained were measured by EDS to determine whether or not an interface layer was present. The measurement results are shown in the column "Presence or absence of interface layer" in Table 1.

[0077] <Evaluation> A cutting test was carried out on the obtained coated tool. The test conditions are shown below, and the test results are shown in Table 1.

[0078] Machining method: Turning Cutting speed: 180 m / min Feed: 0.4 mm / rev Depth of cut: 1.5 mm Workpiece: FCD700 φ200 round bar Machining condition: WET Evaluation items: Check the wear width (mm) and damage width (mm) after 15 minutes of machining Other: Measurements were performed with n=2 and the average value was calculated.

[0079] The results of the wear width after 15 minutes of machining are shown in the "Wear Width (mm)" column. The smaller the wear width value, the higher the wear resistance. The results of the damage width after 15 minutes of machining are shown in the "Damage Width (mm)" column. The smaller the damage width value, the higher the chipping resistance.

[0080]

[0081] Samples Nos. 1 and 3 exhibited high wear resistance and chipping resistance. A wear width of 0.20 mm or less can be considered to have high wear resistance.

[0082] For Samples No. 1 and 3, cross-sectional observation using an SEM was performed to confirm that the internal regions contained no β-phase particles. As a result, in Samples No. 1 and 3, the area ratio of β-phase particles was less than 5%, and the internal regions contained no β-phase particles.

[0083] Sample No. 1 had an interface layer. The composition of this interface layer was measured by EDS. The EDS measurement conditions were the same as those used to measure the composition of the cemented carbide. The EDS measurement results showed that this interface layer contained Co and C.

[0084] The average contents of Co and C were measured according to the methods exemplified above. As a result, the average Co content was 2 mass % and the average C content was 4 mass %. In the interface layer, the Co content decreased and the C content increased with increasing distance from the substrate.

[0085] The interface layer contained Ti as a main component. The average thickness of the interface layer was measured according to the method exemplified above. The measurement was performed at 10 measurement points using an SEM. As a result, the average thickness of the interface layer was 0.2 μm.

[0086] DESCRIPTION OF SYMBOLS 1 coated tool 3 substrate 5 coating layer 7 surface region 9 surface 11 internal region 13 interface layer 15 TiCN layer 17 Al2O3 layer 19 TiN layer 21 first surface (upper surface) 23 second surface (side surface) 25 cutting edge 27 through hole 101 cutting tool 103 holder 103a first end 103b second end 105 pocket 107 screw

Claims

1. A coated tool comprising: a substrate; and a coating layer located on the substrate, wherein the substrate is a cemented carbide having a hard phase containing W and C and a binder phase containing Co, and has a surface region extending from the surface toward the interior, wherein the surface region has an average Co content of 5.5 to 7 mass %, an average Vickers hardness of 1500 to 1600 Hv, and a standard deviation, which is an index of variation in the Co content, of 0.1 to 0.5 mass %.

2. The coated tool according to claim 1, wherein the substrate further has an inner region extending from the surface region toward the interior, and the inner region has a higher average Vickers hardness than the surface region.

3. The coated tool according to claim 2, wherein the inner region has an average Co content of 5.5 to 7 mass % and an average Vickers hardness of 1520 to 1620 Hv.

4. The coated tool according to any one of claims 1 to 3, further comprising an interface layer at the interface between the substrate and the coating layer.

5. The coated tool according to claim 4, wherein the interface layer contains Co.

6. The coated tool according to claim 5, wherein the average content of Co in the interface layer is 0.1 to 5 mass %.

7. The coated tool according to claim 5 or 6, wherein the interface layer further contains C, and the content ratio of Co decreases and the content ratio of C increases with increasing distance from the substrate.

8. A coated tool according to any one of claims 2 to 7, wherein the inner region is free of β-phase grains consisting of WC and iron-group metals.

9. A coated tool according to any one of claims 1 to 8, wherein the coating layer comprises a TiCN layer and an Al2O3 layer in this order from the substrate side.

10. The coated tool according to any one of claims 1 to 8, wherein the coating layer comprises, in order from the substrate side, a TiN layer, a TiCN layer, and an Al2O3 layer.

11. A cutting tool comprising: a holder extending from a first end to a second end and having a pocket on the side of the first end; and the coated tool according to any one of claims 1 to 10 located in the pocket.

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