Coated tool and cutting tool

Abstract

A coated tool according to one non-limiting aspect of the present disclosure is a cutting tool-shaped coated tool comprising a base and a coating layer positioned on the surface of the base. The coating layer comprises a Ti-based coating layer and an Al2O3 layer. The Ti-based coating layer is in contact with the base. The Al2O3 layer is located further apart from the base than the Ti-based coating layer. In at least a rake face, a plurality of regions surrounded by cracks are present in the uppermost surface of the coating layer. The number of the regions is 25-60 per one field of view, and the regions have an average area of 2,500-4,500 μm2.

Description

Coated tools and cutting tools CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2023-086790, filed May 26, 2023, 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 (coated cutting tool) described in Japanese Patent No. 5962862 (Patent Document 1) is known as a coated tool used in cutting tools and the like. In the coated tool described in Patent Document 1, a coating layer formed on the surface of a substrate includes a Ti compound layer. When a polished surface of the Ti compound layer that is approximately parallel to the surface of the substrate is viewed from above, an area surrounded by cracks is present in the Ti compound layer.

[0004] A non-limiting one-sided coated tool of the present disclosure is a coated tool in the shape of a cutting tool, including a substrate and a coating layer located on the surface of the substrate. The coating layer has a Ti-based coating layer and an Al2O3 layer. The Ti-based coating layer is in contact with the substrate. The Al2O3 layer is located farther from the substrate than the Ti-based coating layer. At least on the rake face, there are multiple regions surrounded by cracks on the outermost surface of the coating layer. In one field of view, there are 25 to 60 such regions, and the average area of ​​the regions is 2500 to 4500 μm 2 is.

[0005] Fig. 2 is a perspective view of 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 plan view of the coated tool shown in Fig. 1, corresponding to one field of view. Fig. 5 is an enlarged view of region IV shown in Fig. 3. Fig. 6 is a perspective view of 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 7 located on a surface 5 of the substrate 3, as a non-limiting example shown in FIGS.

[0008] The coated tool 1 may also have a cutting tool shape. The cutting tool shape may refer to a shape that can be used as a cutting tool, and a specific configuration may include a plate shape. In FIG. 1 , a cutting insert is shown as a non-limiting example of the coated tool 1. Therefore, the cutting tool shape may be rephrased as an insert shape. Note that the form of the coated tool 1 is not limited to a cutting insert.

[0009] The coated tool 1 may have a rake face 9 and a flank face 11, as in the non-limiting example shown in FIG. 1 . The coated tool 1 may also have a plate shape. For example, the coated tool 1 may have a square plate shape. The top surface may be the rake face 9. The side surface may be the flank face 11. The shape of the coated tool 1 is not limited to a square plate shape. For example, the rake face 9 (top surface) may be triangular, pentagonal, hexagonal, or circular.

[0010] The coated tool 1 is not limited to a specific size. For example, the length of one side of the rake face 9 (upper surface) may be set to about 3 to 20 mm. Also, the height from the rake face 9 (upper surface) to the surface (lower surface) located opposite the rake face 9 may be set to about 5 to 20 mm.

[0011] The coated tool 1 may have a cutting edge ridge 13 located at the intersection of the rake face 9 and the flank 11. The cutting edge ridge 13 may be a portion of the intersection of the rake face 9 and the flank 11 that has been subjected to cutting edge treatment. The cutting edge ridge 13 may be located over the entire intersection of the rake face 9 and the flank 11, or may be located over only a portion of this intersection. The cutting edge ridge 13 can be used to cut a workpiece when manufacturing a machined product using the coated tool 1. The cutting edge ridge 13 may also be referred to as a cutting edge.

[0012] As a non-limiting example shown in FIG. 2, the coating layer 7 may include a Ti-based coating layer 15 (titanium-based coating layer) and an Al2O3 layer 17 (alumina layer).

[0013] The Ti-based coating layer 15 may be in contact with the substrate 3. The Ti-based coating layer 15 may also be called an underlayer.

[0014] The Al2O3 layer 17 may be located farther from the substrate 3 than the Ti-based coating layer 15. Alternatively, the Al2O3 layer 17 may be located farthest from the substrate 3 in the coating layer 7. The Al2O3 layer 17 may include the outermost surface 19 of the coating layer 7. In other words, the Al2O3 layer 17 may be the outermost layer.

[0015] At least on the rake face 9, a plurality of regions 23 surrounded by cracks 21 may be present on the outermost surface 19 (see FIG. 3 ). In addition to the rake face 9, a plurality of regions 23 may also be present on the outermost surface 19 on the flank 11 and / or cutting edge ridge 13. The presence of a plurality of regions 23 on the outermost surface 19 may be confirmed by observing the outermost surface 19 using, for example, a metallurgical microscope.

[0016] The region 23 may be formed by a plurality of cracks 21. The cracks 21 may open on the outermost surface 19 (see FIGS. 2 and 4). The cracks 21 may also be called fissures.

[0017] Here, the number of regions 23 in one visual field may be 25 to 60. Also, the average area of ​​the regions 23 in one visual field may be 2500 to 4500 μm 2In this way, when many small-average-area regions 23 are present on the outermost surface 19 at least on the rake face 9, the toughness of the coating layer 7 (AlO layer 17) is likely to be improved. Therefore, the coated tool 1 has high wear resistance.

[0018] One field of view may refer to one field of view in a metallurgical microscope. More specifically, one field of view may refer to a range of 311 μm × 411 μm in a micrograph obtained by photographing the outermost surface 19 at 200x magnification using a metallurgical microscope. Furthermore, multiple photographed locations may be used. In this case, the number of regions 23 may be an average value. The number of photographed locations may be, for example, three.

[0019] The crack 21 may extend from the outermost surface 19 toward the substrate 3, as in the non-limiting example shown in Figure 2. In other words, the coating layer 7 may have a crack 21 extending from the outermost surface 19 toward the substrate 3. Furthermore, the coating layer 7 may have a plurality of cracks 21.

[0020] The orientation strength of the Al2O3 layer 17 may be 90% or more. In this case, the number of regions 23 may be 30 or more. The higher the orientation strength of the Al2O3 layer 17, the more likely the number of cracks 21 and the number of regions 23 tend to increase. Note that when the orientation strength of the Al2O3 layer 17 is 90% or more, the number of regions 23 may be 45 or less. Furthermore, the upper limit of the orientation strength of the Al2O3 layer 17 is not limited to a specific value. For example, the orientation strength of the Al2O3 layer 17 may be 98% or less.

[0021] The orientation strength of the Al2O3 layer 17 may be 93% or more. In this case, the number of regions 23 may be 40 or more. The average area of ​​the regions 23 may be 2500 to 3300 μm 2 In these cases, the wear resistance is likely to be improved.

[0022] The orientation strength of the Al2O3 layer 17 may be measured by an electron backscatter diffraction (EBSD) method.

[0023] The substrate 3 may be a sintered alloy. The sintered alloy may be made of a cemented carbide. In other words, the substrate 3 may be made of a cemented carbide. The cemented carbide may contain a hard phase and a binder phase. The hard phase in the cemented carbide may contain, for example, tungsten carbide (WC). Furthermore, the hard phase in the cemented carbide may contain WC as a main component. In other words, the cemented carbide may be a WC-based cemented carbide. The "main component" may refer to a component having the largest mass percentage value compared to other components.

[0024] The binder phase in the cemented carbide may contain an iron group metal. Examples of the iron group metal include cobalt (Co). The binder phase in the cemented carbide may contain an iron group metal as a main component. The binder phase can function as a phase that bonds adjacent hard phases.

[0025] The substrate 3 may be made of a cemented carbide. In this case, the hard phase may be made of WC. Alternatively, the hard phase may contain a cubic crystal structure compound in addition to WC. In this case, the cubic crystal structure compound may be composed of at least one selected from carbides, nitrides, carbonates, nitrides, and mutual solid solutions of elements in Groups 4, 5, and 6 of the periodic table. That is, the hard phase may be composed of WC and at least one cubic crystal structure compound selected from carbides, nitrides, carbonates, nitrides, and mutual solid solutions of elements in Groups 4, 5, and 6 of the periodic table. Alternatively, the binder phase may be mainly composed of Co.

[0026] The composition of the substrate 3 may be measured by, for example, 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).

[0027] The Ti-based coating layer 15 may be a single layer. The composition of the Ti-based coating layer 15 may include, for example, TiN. The Ti-based coating layer 15 may be a TiN layer.

[0028] The coating layer 7 is not limited to a specific thickness. For example, the Ti-based coating layer 15 may have an average thickness of 0.1 to 1 μm, and the AlO layer 17 may have an average thickness of 1 to 15 μm.

[0029] The average thickness of the coating layer 7 may be measured by cross-sectional observation using an electron microscope. Specifically, the average thickness of the coating layer 7 may be measured in a 40 μm × 50 μm area of ​​a micrograph obtained by photographing a cross section perpendicular to the surface 5 of the substrate 3 using an electron microscope at a magnification of 3000 times, and the thickness of the object to be measured, such as the Ti-based coating layer 15, is measured at five measurement points at 5 μm intervals along a direction perpendicular to the thickness direction of the coating layer 7, with the total number of photographed points being three. Note that the average thickness of the coating layer 7 does not need to be measured at multiple cross sections; it is sufficient to measure it at one cross section.

[0030] 2, the coating layer 7 may include, in order from the substrate 3, a Ti-based coating layer 15, a first TiCN layer 25, a second TiCN layer 27, a TiCNO layer 29 (titanium carbonate nitride layer), and an Al2O3 layer 17. In this case, the life of the coated tool 1 is likely to be extended.

[0031] The first TiCN layer 25 may be a so-called MT (moderate temperature) TiCN layer. The first TiCN layer 25 may have an average thickness of 2 to 15 μm. In this case, the first TiCN layer 25 has high wear resistance and chipping resistance. The titanium carbonitride crystals contained in the first TiCN layer 25 may be columnar crystals elongated in the thickness direction of the coating layer 7. The first TiCN layer 25 may be in contact with the Ti-based coating layer 15.

[0032] The second TiCN layer 27 may be a so-called HT (high temperature)-TiCN layer. The second TiCN layer 27 may have an average thickness of 10 to 900 nm. The second TiCN layer 27 may be in contact with the first TiCN layer 25.

[0033] The average thickness of the TiCNO layer 29 may be set to 200 to 2000 nm, which is likely to improve adhesion to the Al2O3 layer 17. The TiCNO layer 29 may be in contact with the second TiCN layer 27.

[0034] The average thickness of the Al 2 O 3 layer 17 may be greater than the average thickness of the TiCNO layer 29. The Al 2 O 3 layer 17 may be in contact with the TiCNO layer 29.

[0035] The coating layer 7 may be located on the entire surface 5 of the substrate 3, or may be located on only a portion thereof. That is, the coating layer 7 may be located on at least a portion of the surface 5 of the substrate 3 (at least a portion corresponding to the rake face 9).

[0036] The coating layer 7 may be formed by a chemical vapor deposition (CVD) method. In other words, the coating layer 7 may be a CVD film.

[0037] The coated tool 1 may have a through hole 31. The through hole 31 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 31 may be formed from the rake face 9 (upper surface) to the surface (lower surface) located opposite the rake face 9, or may open in these surfaces. Note that there is no problem even if the through holes 31 are configured to open in opposing regions of the flank face 11 (side surface).

[0038] <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.

[0039] When manufacturing a coated tool, a substrate may be prepared first. This description will be given taking as an example a case where a substrate made of a sintered alloy (carbide alloy) is prepared as the substrate. First, a mixed powder may be obtained by adding metal powder, carbon powder, etc. to an inorganic powder such as a carbide, nitride, carbonitride, or oxide that can be fired to form a substrate, and mixing the powder. This mixed powder may then be molded into a desired cutting tool shape by a known molding method such as press molding, casting, extrusion, or cold isostatic pressing. The resulting molded body may then be fired in a vacuum or a non-oxidizing atmosphere to obtain a substrate made of a sintered alloy (carbide alloy).

[0040] Next, a coating layer may be formed on the surface of the obtained substrate by a CVD method. The conditions for forming each layer will be described below in order, taking as an example a case where the coating layer has, from the substrate side, a Ti-based coating layer, a first TiCN layer (MT-TiCN layer), a second TiCN layer (HT-TiCN layer), a TiCNO layer, and an Al2O3 layer.

[0041] When depositing a TiN layer as a Ti-based coating layer, a mixed gas containing 0.5 to 10 volume % titanium tetrachloride (TiCl4) gas, 10 to 60 volume % nitrogen (N2) gas, and the remainder hydrogen (H2) gas may be prepared as a reaction gas composition. This mixed gas may then be introduced into a chamber, and the deposition temperature may be set to 800 to 900°C and the pressure may be set to 8 to 50 kPa to deposit the TiN layer.

[0042] The first TiCN layer (MT-TiCN layer) may be formed as follows. First, a mixed gas containing 0.5 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) may be prepared as the reaction gas composition. This mixed gas may then be introduced into a chamber, and the film formation temperature may be set to a relatively low temperature of 800 to 900°C, and the pressure may be set to 5 to 25 kPa, to form the first TiCN layer. If the content of acetonitrile (CHCN) gas is increased in the later stage of film formation compared to the early stage, the average crystal width of the columnar titanium carbonitride crystals constituting the first TiCN layer is likely to be larger on the outermost surface side than on the substrate side.

[0043] The second TiCN layer (HT-TiCN layer) may be formed as follows. First, a mixed gas containing 1 to 4 volume percent titanium tetrachloride (TiCl4) gas, 5 to 20 volume percent nitrogen (N2) gas, 0.1 to 10 volume percent methane (CH4) gas, and the remainder hydrogen (H2) gas may be prepared as the reaction gas composition. Then, this mixed gas may be introduced into a chamber, and the second TiCN layer may be formed at a film formation temperature of 900 to 1010°C and a pressure of 5 to 40 kPa. The second TiCN layer may be formed at a higher temperature than the first TiCN layer.

[0044] The TiCNO layer may be formed as follows. First, a mixed gas containing 3 to 15 volume percent titanium tetrachloride (TiCl4) gas, 3 to 50 volume percent nitrogen (N2) gas, 0.5 to 15 volume percent methane (CH4) gas, 0.5 to 10 volume percent carbon monoxide (CO) 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 film formation temperature may be set to 900 to 1010°C and the pressure may be set to 5 to 40 kPa to form the TiCNO layer.

[0045] The Al2O3 layer may be formed as follows. First, a mixed gas containing 3.5 to 15 volume percent aluminum trichloride (AlCl3) gas, 0.5 to 2.5 volume percent hydrogen chloride (HCl) gas, 0.5 to 5 volume percent carbon dioxide (CO2) gas, 0.3 to 1 volume percent 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 film formation temperature may be set to 900 to 1010°C and the pressure may be set to 5 to 20 kPa.

[0046] Furthermore, the Al2O3 layer may be formed by setting the gas flow rate of aluminum trichloride (AlCl3) gas to 3 to 5 volume %, the gas flow rate of hydrogen chloride (HCl) gas to 0.7 to 0.9 volume %, the gas flow rate of carbon dioxide (CO2) gas to 4 to 5 volume %, the gas flow rate of hydrogen sulfide (HS) gas to 0.6 to 0.9 volume %, and the gas flow rate of hydrogen (H2) gas to 88 to 93 volume %. When the Al2O3 layer is formed under these film formation conditions, the Al2O3 layer is likely to have a high orientation strength of 90% or more.

[0047] The coating layer may be formed and then cooled to obtain a coated tool. When the coating is formed under the above-mentioned conditions, cracks extending from the outermost surface toward the substrate are likely to form in the coating layer. Furthermore, when an Al2O3 layer is formed under the above-mentioned conditions, the number of regions in one field of view is likely to be 25 to 60, and the average area of ​​the regions is likely to be 2500 to 4500 μm2. 2 The reason for this is presumably due to the thermal expansion coefficient of Al2O3 in the highly oriented Al2O3 layer. That is, in Al2O3, the (0001) plane tends to have a higher tensile residual stress than the (1012) or (1014) planes. Therefore, the higher the proportion of the (0001) plane, the higher the tensile residual stress, and the greater the difference in thermal expansion between Al2O3 and the substrate, making cracks more likely to occur. As a result, the number of cracks tends to increase, and the number of regions tends to increase. As a result, the number of regions tends to be 25 to 60 in one field of view, and the average area of ​​the regions is 2500 to 4500 μm 2 It can be inferred that this makes it easier for

[0048] 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.

[0049] <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 .

[0050] 5 , the cutting tool 101 may include a holder 103 and a coated tool 1. The holder 103 may extend from a first end 103a to a second end 103b and may have a pocket 105 on the side of the first end 103a. 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 of the coated tool 1.

[0051] 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.

[0052] The coated tool 1 may be attached to the pocket 105 so that at least a part of the cutting edge ridge 13 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 31 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] For example, the coated tool 1 and cutting tool 101 may have the following configurations: (1) The coated tool is a cutting tool-shaped coated tool including a substrate and a coating layer located on the surface of the substrate, the coating layer having a Ti-based coating layer and an Al2O3 layer, the Ti-based coating layer being in contact with the substrate, the Al2O3 layer being located farther from the substrate than the Ti-based coating layer, and at least on the rake face, there are a plurality of regions surrounded by cracks on the outermost surface of the coating layer, 25 to 60 of the regions are present in one field of view, and the average area of ​​the regions is 2500 to 4500 μm 2(2) In the coated tool of (1) above, when the orientation strength of the Al2O3 layer is 90% or more, the number of the regions may be 30 or more. (3) In the coated tool of (1) or (2) above, the substrate may be a sintered alloy made of cemented carbide containing a hard phase and a binder phase. (4) In any one of the coated tools of (1) to (3) above, the substrate may be made of cemented carbide containing a hard phase and a binder phase, the hard phase may be made of tungsten carbide or tungsten carbide and at least one cubic crystal structure compound selected from carbides, nitrides, carbonates, nitrides, and oxynitrides of elements of Groups 4, 5, and 6 of the Periodic Table, and their mutual solid solutions, and the binder phase may be mainly composed of cobalt. (5) In the coated tool of any one of (1) to (4) above, the coating layer may have, in order from the substrate, the Ti-based coating layer, a first TiCN layer, a second TiCN layer, a TiCNO layer, and the Al2O3 layer. (6) 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 (5) above located in the pocket.

[0057] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0058] [Samples No. 1 to 5] <Preparation of Coated Tools> First, a substrate was prepared. Specifically, a mixed powder was obtained by mixing 6 mass% of metallic cobalt powder having an average particle size of 1.2 μm, 0.5 mass% of titanium carbide powder having an average particle size of 2 μm, 5 mass% of niobium carbide powder having an average particle size of 2 μm, and the remainder, tungsten carbide powder having an average particle size of 1.5 μm. The average particle size of each powder was measured by the Microtrac method.

[0059] The resulting mixed powder was then press-molded into a cutting tool shape (CNMG120408) to obtain a compact. The resulting compact was then subjected to a binder removal treatment and fired in a non-oxidizing atmosphere to obtain a substrate made of cemented carbide. The firing temperature was set to 1450°C, the firing time was set to 1 hour, and an argon atmosphere was used as the non-oxidizing atmosphere.

[0060] The composition of the obtained cemented carbide 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 the average value of measurements at five locations was measured. Five elements, namely, tungsten carbide, cobalt, titanium, carbon, and nitrogen, were selected for measurement by EDS.

[0061] The EDS measurement results showed that the obtained cemented carbide contained a hard phase and a binder phase. More specifically, the obtained cemented carbide contained a hard phase made of WC and a binder phase mainly composed of Co.

[0062] Next, a coating layer was formed on the surface of the obtained substrate by CVD. After the coating layer was formed, the substrate was cooled to obtain the coated tool samples shown in Table 1.

[0063] The samples shown in Table 1 were prepared by first forming a Ti-based coating layer on the surface of a substrate, and then forming a first TiCN layer (MT-TiCN layer), a second TiCN layer (HT-TiCN layer), a TiCNO layer, and an Al2O3 layer on the Ti-based coating layer in this order. The respective film formation conditions were as follows:

[0064] (Deposition conditions for Ti-based coating layer) A single layer of TiN was deposited as the Ti-based coating layer. 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 deposition temperature and pressure were set to 850°C and 18 kPa, respectively. The deposition time was set to 180 minutes.

[0065] (Film formation conditions for the first TiCN layer (MT-TiCN layer)) First, a mixed gas consisting of 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 the chamber, and the film formation temperature was set to 850°C and the pressure to 9 kPa. The film formation time was set to 400 minutes.

[0066] (Film formation conditions for the second TiCN layer (HT-TiCN layer)) First, a mixed gas consisting of 4 volume % titanium tetrachloride (TiCl4) gas, 20 volume % nitrogen (N2) gas, 8 volume % methane (CH4) gas, and the remainder hydrogen (H2) gas was prepared as the reaction gas composition. This mixed gas was then introduced into the chamber, and the film formation temperature was set to 950°C and the pressure to 13 kPa. The film formation time was set to 80 minutes.

[0067] (Film formation conditions for TiCNO layer) First, a mixed gas containing 4 vol% titanium tetrachloride (TiCl4) gas, 20 vol% nitrogen (N2) gas, 8 vol% methane (CH4) gas, 2 vol% carbon monoxide (CO) 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 film formation temperature and pressure were set to 950°C and 10 kPa, respectively. The film formation time was set to 30 minutes.

[0068] (Al2O3 Layer Deposition Conditions) First, a mixed gas containing 3.7 volume % aluminum trichloride (AlCl3) gas, 0.7 volume % hydrogen chloride (HCl) gas, 4.3 volume % carbon dioxide (CO2) gas, 0.3 volume % hydrogen sulfide (HS) gas, and the remainder hydrogen (H2) gas was prepared as the reaction gas composition. This mixed gas was then introduced into the chamber, and the film formation temperature, pressure, and gas flow rate were set as shown in Table 1. The film formation time was set to 300 minutes.

[0069]

[0070] The presence of a region on the outermost surface of the rake face was confirmed using a metallurgical microscope. As a result, it was found that a plurality of regions surrounded by cracks existed on the outermost surface of the rake face of all the coated tools obtained. The regions were composed of a plurality of cracks. The plurality of cracks were open on the outermost surface.

[0071] For the obtained coated tool, the number of regions in one visual field and the average area of ​​the regions in one visual field were measured according to the method exemplified above. Specifically, on the rake face, a metallurgical microscope was used to photograph the outermost surface at 200x magnification, and an area of ​​311 μm x 411 μm in the obtained micrograph was defined as one visual field. Three photographs were taken. The measurement results are shown in Table 2, with the "number (pieces)" and "average area (μm 2 The number of regions is an average value.

[0072] The orientation strength of the Al2O3 layer was measured using the EBSD method. Specifically, the measurement range was a 60 μm cross-sectional polished surface parallel to the substrate surface. The sample was placed in the tube of a field-emission SEM, and an electron beam with an accelerating voltage of 25 kV was irradiated at an incident angle of 70 degrees relative to the polished surface to each crystal grain with a hexagonal crystal lattice present within the measurement range of the polished surface. Using the field-emission SEM and EBSD equipment, the tilt angle of the Al2O3 crystal grains, made by the normal to the (0001) crystal plane of the crystal grain relative to the normal to the substrate surface, was measured at intervals of 0.1 μm / step in the range of 0 to 45 degrees. The measurement results were presented as a tilt angle distribution graph, which was calculated by tallying the frequency of each category. Based on these measurement results, the orientation strength of the Al2O3 layer was determined by calculating the total frequency of crystal grains (interface orientation morphology Al2O3 crystal grains) with measured tilt angles of 0 to 15 degrees. The measurement results are shown in Table 2.

[0073] <Evaluation> A cutting test was carried out on the obtained coated tool under the following conditions: Machining mode: turning Cutting speed: 300 m / min Feed: 0.3 mm / rev Depth of cut: 2 mm Workpiece: SCM435 φ200 round bar Machining condition: WET

[0074] The test results are shown in Table 2. In Table 2, "Cutting time (min) until wear amount reaches 0.2 mm" indicates the time until the wear amount reaches 0.2 mm on the flank face of the cutting edge.

[0075]

[0076] Samples Nos. 1 to 3 showed higher abrasion resistance than samples Nos. 4 and 5.

[0077] In Samples No. 1 to 5, multiple regions existed on the outermost surface of the flank and cutting edge ridge. The same measurements as for the rake face were performed on the flank and cutting edge ridge of Samples No. 1 to 5. As a result, the measurement results for the flank and cutting edge ridge of Samples No. 1 to 5 were substantially the same as those for the rake face.

[0078] DESCRIPTION OF SYMBOLS 1... Coated tool 3... Base body 5... Surface 7... Coating layer 9... Rake face (upper surface) 11... Flank face (side surface) 13... Cutting edge ridge 15... Ti-based coating layer 17... Al2O3 layer 19... Outermost surface 21... Crack 23... Region 25... First TiCN layer 27... Second TiCN layer 29... TiCNO layer 31... Through hole 101... Cutting tool 103... Holder 103a... First end 103b... Second end 105... Pocket 107... Screw

Claims

1. a substrate; a coating layer located on a surface of the substrate, The coating layer is a Ti-based coating layer and an Al ２ O ３ a layer; the Ti-based coating layer is in contact with the substrate, The Al ２ O ３ the layer is located farther from the substrate than the Ti-based coating layer, At least on the rake face, a plurality of regions surrounded by cracks are present on the outermost surface of the coating layer, In one visual field, there are 25 to 60 of the above-mentioned regions, and the average area of ​​the regions is 2500 to 4500 μm ２ That is, coated tools.

2. The Al ２ O ３ 2. The coated tool according to claim 1, wherein the number of the regions is 30 or more when the orientation strength of the layer is 90% or more.

3. 3. The coated tool according to claim 1, wherein the substrate is a sintered alloy made of cemented carbide containing a hard phase and a binder phase.

4. the substrate is made of a cemented carbide containing a hard phase and a binder phase, the hard phase comprises tungsten carbide or tungsten carbide and at least one cubic crystal structure compound selected from the group consisting of carbides, nitrides, carbonates, oxynitrides of elements in Groups 4, 5 and 6 of the Periodic Table, and their mutual solid solutions; 3. The coated tool according to claim 1, wherein the binder phase is mainly composed of cobalt.

5. The coating layer is made up of, in order from the substrate, the Ti-based coating layer, the first TiCN layer, the second TiCN layer, the TiCNO layer, and the Al ２ O ３ 3. The coated tool according to claim 1, having a layer.

6. a holder extending from a first end to a second end and having a pocket on the side of the first end; A cutting tool comprising: the coated tool according to claim 1 or 2 located in the pocket.