Cutting Tools

Abstract

A cutting tool comprising a substrate and a coating disposed on the substrate, the coating including a first layer, the first layer being composed of alternating layers in which first unit layers and second unit layers are alternately stacked, the first unit layer having a hexagonal crystal structure, and the first unit layer being composed of W(C 1-a N a ) x wherein a is 0.3 or more and 0.8 or less, x is 0.8 or more and 1.2 or less, and the second unit layer is Al c Cr 1-c N, and said c is 0.40 or more and 0.80 or less.

Description

[Technical field]

[0001] The present disclosure relates to cutting tools. [Background technology]

[0002] Conventionally, cutting tools including a substrate and a coating disposed on the substrate have been used in cutting processes (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-143690 A [Patent Document 2] International Publication No. 2022 / 176230 Summary of the Invention

[0004] A cutting tool according to one aspect of the present disclosure includes: 1. A cutting tool comprising a substrate and a coating disposed on the substrate, The coating comprises a first layer, the first layer is composed of alternating layers in which first unit layers and second unit layers are alternately laminated, the first unit layer has a hexagonal crystal structure, The first unit layer is W(C 1-a N a ) x It consists of: The a is 0.3 or more and 0.8 or less, The x is equal to or greater than 0.8 and equal to or less than 1.2, The second unit layer is Al c Cr 1-c It consists of N, The cutting tool, wherein c is equal to or greater than 0.40 and equal to or less than 0.80. [Brief description of the drawings]

[0005] [Figure 1]FIG. 1 is a schematic enlarged cross-sectional view of an example of a cutting tool according to a first embodiment. [Diagram 2] FIG. 2 is a schematic enlarged cross-sectional view of another example of the cutting tool according to the first embodiment. [Diagram 3] FIG. 3 is a schematic enlarged cross-sectional view of another example of the cutting tool according to the first embodiment. [Figure 4] FIG. 4 is a schematic enlarged cross-sectional view of another example of the cutting tool according to the first embodiment. [Diagram 5] FIG. 5 is a diagram for explaining an example of the ratio of the thickness of the first unit layer to the thickness of the second unit layer. [Figure 6] FIG. 6 is a schematic enlarged cross-sectional view of an example of a cutting tool according to the second embodiment. [Figure 7] FIG. 7 is a schematic enlarged cross-sectional view of another example of the cutting tool according to the second embodiment. [Figure 8] FIG. 8 is a schematic enlarged cross-sectional view of another example of the cutting tool according to the second embodiment. [Figure 9] FIG. 9 is a schematic enlarged cross-sectional view of another example of the cutting tool according to the second embodiment. [Figure 10] FIG. 10 is a diagram for explaining an example of the ratio of the thickness of the first unit layer to the thickness of the third unit layer. [Figure 11] FIG. 11 is a schematic cross-sectional view of a cathodic arc ion plating apparatus used in the examples. [Figure 12] FIG. 12 is a schematic top view of the cathodic arc ion plating apparatus shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] [Problem that this disclosure aims to solve] Machining plays a central role in manufacturing technology, and there is a constant demand for technological evolution and further sophistication. In cutting technology, high speed, high efficiency, high precision machining, and ultra-fine machining are fundamentally required. A recent trend is that work materials are becoming more difficult to cut, and there is a need to address this. In addition, in cutting sites, attention has been increasingly being paid to the Sustainable Development Goals (SDGs) in recent years in order to realize a sustainable and better world by 2030. Sustainable development means building a social infrastructure that can withstand the threats of nature without compromising the resources needed by future generations. Improvements in cutting technology are expected to reduce the environmental impact, such as reducing the number of processes to save energy during product manufacturing and reducing waste associated with cutting. Against this background, in order to extend the life of cutting tools, the development of coated tool materials that have high high-temperature hardness and combine hardness and toughness has been pursued.

[0007] Conventionally, as coating tool materials, nitride or boronitride coatings mainly composed of Al and Cr have been coated on the substrate surface (Patent Document 1 and Patent Document 2). However, from the viewpoint of SDGs and global environmental conservation, dry machining without cutting oil is required, cutting speeds are becoming faster to improve machining efficiency, and work materials are becoming more diverse, especially in the fields of aircraft and medicine, cutting of heat-resistant alloys and titanium alloys, which are called difficult-to-cut materials, is increasing. For these reasons, the cutting edge temperature of cutting tools during cutting tends to become high. When the cutting edge temperature becomes high, the life of the cutting tool becomes extremely short. Therefore, there is a demand for cutting tools that can exhibit excellent tool life even under such harsh cutting conditions.

[0008] [Effects of this disclosure] According to the present disclosure, it is possible to provide a cutting tool having a long tool life, particularly in cutting operations performed under conditions of high cutting edge temperatures.

[0009] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described. (1) A cutting tool according to one embodiment of the present disclosure includes: 1. A cutting tool comprising a substrate and a coating disposed on the substrate, The coating comprises a first layer, the first layer is composed of alternating layers in which first unit layers and second unit layers are alternately laminated, the first unit layer has a hexagonal crystal structure, The first unit layer is W(C 1-a N a ) x It consists of: The a is 0.3 or more and 0.8 or less, The x is equal to or greater than 0.8 and equal to or less than 1.2, The second unit layer is Al c Cr 1-c It consists of N, The cutting tool, wherein c is equal to or greater than 0.40 and equal to or less than 0.80.

[0010] According to the present disclosure, it is possible to provide a cutting tool having a long tool life, particularly in cutting operations performed under conditions of high cutting edge temperatures.

[0011] (2) In the above (1), the ratio λ2 / λ1 of the thickness λ2 μm of the second unit layer to the thickness λ1 μm of the first unit layer may be 1.0 or more and 5.0 or less, between the first unit layer and the second unit layer adjacent to the first unit layer, which allows the cutting tool to have a longer tool life.

[0012] (3) In (1) or (2) above, The average thickness of the first unit layer is 0.002 μm or more and 0.2 μm or less, The second unit layer may have an average thickness of 0.002 μm or more and 0.2 μm or less. This allows the cutting tool to have a longer tool life.

[0013] (4) In any of (1) to (3) above, the coating further comprises a second layer disposed between the substrate and the first layer; The composition of the second layer may be the same as the composition of the first unit layer or the composition of the second unit layer. This allows the cutting tool to have a longer tool life.

[0014] (5) In (4) above, the composition of the second layer is the same as the composition of the first unit layer; The second layer may have a thickness greater than that of the first unit layer. This allows the cutting tool to have a longer tool life.

[0015] (6) In (4) above, the composition of the second layer is the same as the composition of the second unit layer; The second layer may have a thickness greater than that of the second unit layer. This allows the cutting tool to have a longer tool life.

[0016] (7) In items (1) to (6) above, The coating further includes a third layer provided on a side of the first layer opposite the substrate, The third layer may be made of AlCrCN. This allows the cutting tool to have a longer tool life.

[0017] (8) A cutting tool according to another aspect of the present disclosure includes: 1. A cutting tool comprising a substrate and a coating disposed on the substrate, The coating comprises a Layer 1A, The first A layer is composed of alternating layers in which first unit layers and third unit layers are alternately laminated, the first unit layer has a hexagonal crystal structure, The first unit layer is W(C 1-a N a ) x It consists of: The a is 0.3 or more and 0.8 or less, The x is equal to or greater than 0.8 and equal to or less than 1.2, The third unit layer is Al d Cr 1-d-e M e It consists of N, M is silicon, boron, yttrium, cerium or lanthanum; The d is equal to or greater than 0.40 and equal to or less than 0.80, The cutting tool, wherein e is greater than 0 and is equal to or less than 0.05.

[0018] According to the present disclosure, it is possible to provide a cutting tool having a long tool life, particularly in cutting operations performed under conditions of high cutting edge temperatures.

[0019] (9) In the above (8), between the first unit layer and the third unit layer adjacent to the first unit layer, the ratio λ3 / λ1 of the thickness λ3 μm of the third unit layer to the thickness λ1 μm of the first unit layer may be 1.0 or more and 5.0 or less. This allows the cutting tool to have a longer tool life.

[0020] (10) In the above (8) or (9), the M may be silicon. This allows the cutting tool to have a longer tool life.

[0021] (11) In the above (8) or (9), the M may be boron. This allows the cutting tool to have a longer tool life.

[0022] (12) In any of (8) to (11) above, The average thickness of the first unit layer is 0.002 μm or more and 0.2 μm or less, The third unit layer may have an average thickness of 0.002 μm or more and 0.2 μm or less. This allows the cutting tool to have a longer tool life.

[0023] (13) In any of (8) to (12) above, The coating further includes a second A layer disposed between the substrate and the first A layer; The composition of the second A layer may be the same as the composition of the first unit layer or the composition of the third unit layer. This allows the cutting tool to have a longer tool life.

[0024] (14) In (13) above, the composition of the second A layer is the same as the composition of the first unit layer, The thickness of the second A layer may be greater than the thickness of the first unit layer. This allows the cutting tool to have a longer tool life.

[0025] (15) In (13) above, the composition of the second A layer is the same as the composition of the third unit layer; The thickness of the second A layer may be greater than the thickness of the third unit layer. This allows the cutting tool to have a longer tool life.

[0026] (16) In any of (8) to (15) above, The coating further includes a 3A layer provided on the opposite side of the 1A layer from the substrate, the 3A layer is made of AlCrMeCN, The Me may be silicon, boron, yttrium, cerium or lanthanum. This allows the cutting tool to have a longer tool life.

[0027] [Details of the embodiment of the present disclosure] Specific examples of the cutting tool of the present disclosure will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, depth, etc. have been appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0028] In this disclosure, an expression in the form "A to B" means the upper and lower limits of a range (i.e., A or more and B or less). When no unit is specified for A and a unit is specified only for B, the unit of A and the unit of B are the same.

[0029] 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.

[0030] In the present disclosure, when one or more numerical values ​​are described as the lower limit and the upper limit of a numerical range, the combination of any one numerical value described as the lower limit and any one numerical value described as the upper limit is also disclosed. For example, when a1 or more, b1 or more, and c1 or more are described as the lower limit, and a2 or less, b2 or less, and c2 or less are described as the upper limit, a1 or more and a2 or less, a1 or more and b2 or less, a1 or more and c2 or less, b1 or more and a2 or less, b1 or more and b2 or less, b1 or more and c2 or less, c1 or more and a2 or less, c1 or more and b2 or less, and c1 or more and c2 or less are disclosed.

[0031] [Embodiment 1: Cutting tool (1)] A cutting tool according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 5. FIG. A cutting tool 1 according to one embodiment of the present disclosure (hereinafter also referred to as "embodiment 1") includes: A cutting tool comprising a substrate 2 and a coating 3 disposed on the substrate 2, The coating 3 includes a first layer 13, The first layer 13 is composed of alternating layers in which the first unit layers 12 and the second unit layers 15 are alternately laminated, The first unit layer 12 has a hexagonal crystal structure, The first unit layer 12 is made of W(C 1-a N a ) x It consists of: a is equal to or greater than 0.3 and equal to or less than 0.8, x is equal to or greater than 0.8 and equal to or less than 1.2; The second unit layer 15 is made of Al c Cr 1-c It consists of N, The c is greater than or equal to 0.40 and less than or equal to 0.80 for the cutting tool.

[0032] The cutting tool 1 of the first embodiment can have a long tool life, especially in cutting operations performed under conditions where the cutting edge temperature is high. The reason for this is presumably as follows.

[0033] The first unit layer 12 is made of W(C 1-a N a ) x Since the first unit layer 12 contains C (carbon), the friction coefficient at the contact interface with the workpiece is reduced, and the cutting resistance can be reduced. 1-a N a ) x Because it contains N (nitrogen), its heat resistance is improved by about 150°C compared to WC. As a result, the first layer including the first unit layer can improve adhesion resistance, sliding properties, and wear resistance in processes where the cutting edge becomes hot, such as dry cutting processes. Therefore, cutting tools including the first layer have an improved tool life.

[0034] The second unit layer 15 is made of Al c Cr 1-c The second unit layer 12 is made of N. The second unit layer 15 contains Al. Since Al is easily oxidized, a dense oxide layer made of Al2O3 tends to be easily formed on the surface side of the first layer 13 in the coating including the second unit layer 12. As a result, the heat insulating property and oxidation resistance of the first layer 13 can be improved. Therefore, the tool life of a cutting tool including the first layer 13 is improved.

[0035] The first layer 13 is composed of alternating layers in which the first unit layers 12 and the second unit layers 15 are alternately stacked. At the interface between the first unit layers 12 and the second unit layers 15, the composition and crystal lattice are discontinuous. Therefore, if a crack occurs from the surface of the coating 3 during cutting, the crack can be prevented from progressing at the interface. In a coating including the first layer, chipping and damage are prevented. Therefore, a cutting tool including the first layer 13 has an improved tool life.

[0036] <Cutting tools> As shown in Fig. 1 and Fig. 2, a cutting tool 1 according to an embodiment of the present invention includes a substrate 2 and a coating 3 disposed on the substrate 2. The coating 3 can cover at least a portion of the substrate 2 involved in cutting. The coating 3 may cover the entire surface of the substrate 2. Even if the configuration of the coating 3 is partially different, it does not deviate from the scope of this embodiment. In this specification, the portion of the substrate 2 involved in cutting refers to an area on the surface of the substrate 2 that is at least within 50 µm, 100 µm, or 300 µm away from the cutting edge.

[0037] The cutting tool 1 of this embodiment can be suitably used as cutting tools 1 such as drills, end mills, indexable cutting tips for drills, indexable cutting tips for end mills, indexable cutting tips for milling, indexable cutting tips for turning, metal saws, gear cutting tools, reamers, taps, etc.

[0038] <Base material> Any known material can be used as the substrate 2. For example, the substrate 2 may be made of any of cemented carbide (WC-based cemented carbide, cemented carbide containing WC and Co, cemented carbide containing carbonitrides such as Ti, Ta, Nb, etc., added to WC and Co), cermet (mainly composed of TiC, TiN, TiCN, etc.), high-speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cubic boron nitride sintered body, and diamond sintered body.

[0039] The substrate 2 may be, in particular, a WC-based cemented carbide or a cermet (particularly, a TiCN-based cermet). The WC-based cemented carbide or the cermet has an excellent balance between hardness and strength, particularly at high temperatures, and therefore, when used as the substrate 2 of the cutting tool 1, it can contribute to extending the life of the cutting tool 1.

[0040] <Coating> The coating 3 of the first embodiment includes a first layer 13. The coating 3 covers the substrate 2, thereby improving various properties of the cutting tool 1, such as wear resistance and chipping resistance, and has the effect of extending the life of the cutting tool 1.

[0041] The coating 3 may include other layers in addition to the first layer 13. The other layers include a second layer 16 disposed between the substrate 2 and the first layer 13, and a third layer 14 provided on the side of the first layer 13 opposite the substrate 2, as shown in Figures 3 and 4.

[0042] The coating 3 may have a total thickness of 0.4 μm or more and 15 μm or less. When the total thickness of the coating 3 is 0.4 μm or more, the effect of extending the life of the cutting tool 1 by providing the coating 3 is easily obtained. On the other hand, when the total thickness of the coating 3 is 15 μm or less, chipping in the coating 3 is unlikely to occur in the early stage of cutting, and the life of the cutting tool 1 can be extended.

[0043] The overall thickness of the coating 3 can be measured by observing a cross section of the coating 3 using a scanning electron microscope (SEM). The specific measurement method is as follows. The cutting tool 1 is cut in a direction along the normal to the surface of the coating 3 to prepare a cross section sample. The cross section sample is observed with the SEM. The observation magnification is 5000 to 10000 times, and the measurement field of view is 100 to 500 μm. 2 The thickness width is measured at three points in one visual field of the coating 3, and the average value of the thickness widths at the three points is calculated. The average value corresponds to the thickness of the coating 3. The thickness of each layer described later is also measured in the same manner unless otherwise specified.

[0044] The compressive residual stress of the coating 3 may have an absolute value of 6 GPa or less. The compressive residual stress of the coating 3 is a type of internal stress (intrinsic strain) that exists throughout the coating 3, and refers to a stress expressed as a "-" (negative) numerical value (unit: "GPa" is used in this embodiment). Therefore, the concept of a large compressive residual stress refers to a large absolute value of the numerical value, and the concept of a small compressive residual stress refers to a small absolute value of the numerical value. In other words, the absolute value of the compressive residual stress being 6 GPa or less means that the compressive residual stress of the coating 3 is -6 GPa or more and 0 GPa or less.

[0045] When the compressive residual stress of the coating 3 is 0 GPa or less, it is easy to suppress the growth of cracks that initiate from the outermost surface of the coating 3. On the other hand, when the absolute value of the compressive residual stress is 6 GPa or less, the magnitude of the stress is appropriate, and it is easy to suppress peeling of the coating 3 from the edge portion of the cutting tool 1 before cutting begins.

[0046] The compressive residual stress of the coating 3 was measured using an X-ray residual stress device. 2 It is measured by the ψ method (see pages 54-66 of "X-Ray Stress Measurement Method" (published by Yokendo Co., Ltd., 1981, by the Japan Society for Materials Science)).

[0047] The first unit layer 12 can have a hexagonal crystal structure. When the first unit layer 12 has a hexagonal crystal structure, the abrasion resistance of the coating 3 is improved. The second unit layer 15 can include a cubic crystal structure. When the second unit layer 15 has a cubic crystal structure, the hardness of the coating 3 is improved. The crystal structure of each layer in the coating 3 can be analyzed by an X-ray diffraction device known in the art.

[0048] The hardness of the coating 3 is highly effective when it is between 30 GPa and 55 GPa, and may be between 35 GPa and 50 GPa. This means that the coating 3 has sufficient hardness. The hardness of the entire coating 3 is measured by a nanoindenter method (Nano Indenter XP manufactured by MTS Corporation). Specifically, this is performed according to a method conforming to ISO14577, with a measurement load of 10 mN (1 gf), the hardness is measured at three points on the surface of the coating 3, and the average value of the hardness at the three points is calculated. This average value corresponds to the hardness of the coating 3.

[0049] <1st layer> The first layer 13 in this embodiment is composed of alternating layers in which the first unit layers 12 and the second unit layers 15 are alternately stacked. The fact that the first layer 13 is composed of alternating layers in which the first unit layers 12 and the second unit layers 15 are alternately stacked can be confirmed by observing a thin slice sample including a cross section of the coating 3 with a TEM (transmission electron microscope) and observing the difference in contrast.

[0050] Either of the first unit layer 12 or the second unit layer 15 may be disposed at a position closest to the substrate 2. In FIG. 1, the first unit layer 12 is disposed directly on the substrate 2. In FIG. 2, the second unit layer 15 is disposed directly on the substrate 2. Either of the first unit layer 12 or the second unit layer 15 may be disposed on the surface side of the coating 3. In FIG. 1, the second unit layer 15 is disposed on the surface side of the coating 3. In FIG. 2, the first unit layer 12 is disposed on the surface side of the coating 3.

[0051] The thickness of the first layer 13 may be 0.5 μm or more and 15 μm or less. When the thickness of the first layer 13 is 0.5 μm or more, excellent wear resistance can be exhibited in continuous cutting. When the thickness of the first layer 13 is 15 μm or less, excellent chipping resistance can be exhibited in interrupted cutting.

[0052] The thickness of the first layer 13 is measured by observing and measuring the cross section of the coating 3 using a transmission electron microscope (TEM). The specific measurement method is as follows. The cutting tool 1 is cut in a direction along the normal to the surface of the coating 3 to prepare a thin sample including the cross section of the coating 3. The thin sample is observed with the TEM. The observation magnification is set to 20,000 to 5,000,000 times, and the measurement field of view is set to 0.0016 to 80 μm. 2 In one visual field, the thickness width is measured at three points of the first layer 13, and the average value of the thickness widths at the three points is calculated. The average value corresponds to the thickness of the first layer 13.

[0053] The first unit layer 12 may have a hexagonal crystal structure. The hexagonal crystal structure is formed by the W(C 1-a N a ) x It can be confirmed by analyzing the first unit layer 12 by XRD measurement that the first unit layer 12 has a hexagonal crystal structure. In the obtained XRD spectrum, ε-W2C (01-076-7103) and W 4.6 When a peak attributable to a hexagonal crystal structure as defined in N4 (01-077-2001) is observed, it is confirmed that the first unit layer 12 has a hexagonal crystal structure.

[0054] Even when the coating includes, in addition to the first unit layer, other layers such as the second unit layer 15, the second layer 16, the third layer 14, and an intermediate layer, and peaks originating from layers or the substrate other than the first unit layer 12 (hereinafter also referred to as "other peaks") are detected in the XRD spectrum from the surface of the coating 3, it is possible to identify that the first unit layer 12 has a hexagonal crystal structure.

[0055] The X-ray diffraction measurement can be performed using a device such as "SmartLab" (product name) manufactured by Rigaku Corp. The conditions for the XRD measurement are as follows. (XRD measurement conditions) Scanning axis: 2θ-θ X-ray source: Cu-Kα ray (1.541862Å) Detector: 0-dimensional detector (scintillation counter) Tube voltage: 45kV Tube current: 40mA Incident optical system: Use of mirrors Receiving optical system: Use of analyzer crystal (PW3098 / 27) Step: 0.03° Accumulation time: 2 seconds Scan range (2θ): 10°~120°

[0056] <Composition of the first unit layer and composition of the second unit layer> The first unit layer 12 is made of W(C 1-a N a ) x where a is 0.3 or more and 0.8 or less, and x is 0.8 or more and 1.2 or less. This makes the crystal structure of the first unit layer 12 a hexagonal system, and the heat resistance, oxidation resistance, and wear resistance of the first unit layer 12 can be improved.

[0057] The lower limit of a is 0.3 or more, and may be 0.35 or more, 0.40 or more, or 0.45 or more. The upper limit of a is 0.8 or less, and may be 0.75 or less, 0.70 or less, or 0.65 or less. a may be 0.35 or more and 0.75 or less, 0.40 or more and 0.70 or less, or 0.45 or more and 0.65 or less.

[0058] The lower limit of x is 0.8 or more, may be 0.85 or more, or may be 0.90 or more. The upper limit of x is 1.2 or less, may be 1.15 or less, or may be 1.10 or less. x may be 0.85 or more and 1.15 or less, may be 0.90 or more and 1.10 or less, or may be 1.00.

[0059] In the present disclosure, "the first unit layer is W(C 1-a N a ) x The term "consisting of" means that the first unit layer 12 is made of W(C 1-a N a ) xThis means that the first unit layer 12 may contain unavoidable impurities in addition to the above. Examples of unavoidable impurities include oxygen and carbon. The total content of unavoidable impurities in the first unit layer 12 may be greater than 0 atomic % and less than 1 atomic %. In this disclosure, "atomic %" refers to the ratio (%) of the number of atoms to the total number of atoms constituting the layer.

[0060] The second unit layer 15 is made of Al c Cr 1-c N, and c is 0.40 or more and 0.80 or less. The second unit layer 15 can improve the heat resistance, oxidation resistance, and toughness of the coating 3. The lower limit of c is 0.40 or more, and may be 0.45 or more, 0.50 or more, or 0.55 or more. The upper limit of c is 0.80 or less, and may be 0.75 or less, 0.70 or less, or 0.65 or less. c may be 0.45 or more and 0.75 or less, 0.50 or more and 0.70 or less, or 0.55 or more and 0.65 or less.

[0061] In the present disclosure, "the second unit layer is Al c Cr 1-c The term "made of AlN" means that the second unit layer 15 is made of AlN as long as it does not impair the effect of the present disclosure. c Cr 1-c This means that the second unit layer 15 may contain unavoidable impurities in addition to N. Examples of the unavoidable impurities include oxygen and carbon. The total content of the unavoidable impurities in the second unit layer 15 may be greater than 0 atomic % and less than 1 atomic %.

[0062] The above a, the above x, the above c, and the content of inevitable impurities in the first unit layer 12 and the content of inevitable impurities in the second unit layer 15 are measured by performing elemental analysis on the cross section of the coating 3 using a transmission electron microscope (TEM). A specific measurement method is as follows. The cutting tool 1 is cut in a direction along the normal line of the surface of the coating 3 to prepare a thin sample including the cross section of the coating 3. An electron beam is irradiated onto the thin sample using an EDS (Energy Dispersive X-ray Spectroscopy) attached to the TEM, and the energy and number of occurrences of characteristic X-rays generated at that time are measured to perform elemental analysis of the first unit layer 12 and the second unit layer 15. Five layers each of the first unit layer 12 and the second unit layer 15 are arbitrarily selected and elemental analysis is performed. The average composition of the five first unit layers 12 is obtained. The average composition corresponds to the composition of the first unit layer 12. The average composition of the five second unit layers 15 is obtained. This average composition corresponds to the composition of second unit layer 15. When the number of layers of each of first unit layer 12 and second unit layer 15 is four or less, elemental analysis is performed on all layers to determine the average composition of first unit layer 12 and second unit layer 15. It has been confirmed that as long as the measurement is performed using the same cutting tool 1, there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0063] In the present disclosure, the composition W(C 1-a N a ) x In this case, the number of W atoms is A M1 The total number of C and N atoms for N1 Ratio of A N1 / A M1 In the present disclosure, the composition Al of the second unit layer is 0.8 or more and 1.2 or less. c Cr 1-c In N, the total number of Al and Cr atoms is A M2 Number of N atoms A N2 Ratio of A N2 / A M2 In manufacturing, the ratio A is necessarily between 0.8 and 1.2. N1 / A M1 and ratio A N2 / A M2 can be measured by the Rutherford backscattering (RBS) method. N1 / A M1 and ratio A N2 / A M2 It has been confirmed that the effect of the present disclosure is not impaired if the amount is within the above range.

[0064] <Average thickness of first unit layer and average thickness of second unit layer> The average thickness of the first unit layer 12 may be 0.002 μm or more and 0.2 μm or less, and the average thickness of the second unit layer 15 may be 0.002 μm or more and 0.2 μm or less. This can further suppress the progression of cracks generated on the surface of the coating 3. The lower limit of the average thickness of the first unit layer 12 may be 0.002 μm or more, 0.005 μm or more, or 0.01 μm or more. The upper limit of the average thickness of the first unit layer 12 may be 0.20 μm or less, 0.15 μm or less, or 0.10 μm or less. The average thickness of the first unit layer 12 may be 0.005 μm or more and 0.15 μm or less, or 0.01 μm or more and 0.1 μm or less. The lower limit of the average thickness of the second unit layer 15 may be 0.002 μm or more, 0.005 μm or more, or 0.01 μm or more. The upper limit of the average thickness of the second unit layer 15 may be 0.20 μm or less, 0.15 μm or less, or 0.10 μm or less. The average thickness of the second unit layer 15 may be 0.005 μm or more and 0.15 μm or less, or 0.01 μm or more and 0.10 μm or less.

[0065] The average thickness of the first unit layer 12 and the average thickness of the second unit layer 15 can be measured by the same method as the method for measuring the thickness of the first layer 13 described above.

[0066] As shown in FIG. 5, in the first unit layer 12 and the second unit layer 15 adjacent to the first unit layer 12, the ratio λ2 / λ1 of the thickness λ2μm of the second unit layer 15 to the thickness λ1μm of the first unit layer 12 may be 1.0 or more and 5.0 or less. The second unit layer 15 has high oxidation resistance, and has a low thermal conductivity and is difficult to transmit heat generated during cutting to the base material 2. When the ratio λ2 / λ1 is 1.0 or more, the proportion of the second unit layer 15 in the coating 3 increases relatively, and the amount of Al in the coating 3 increases, thereby improving the heat barrier property of the cutting tool 1 as a whole. The cutting tool 1 having the coating 3 has improved wear resistance, especially during continuous cutting. When λ2 / λ1 is 1.0 or more, the toughness of the coating 3 tends to improve. On the other hand, when λ2 / λ1 is 5.0 or less, the effect of suppressing the progress of cracks by laminating the first unit layer 12 and the second unit layer 15 tends to be easily obtained.

[0067] λ2 / λ1 may be 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, 2.0 or more, or 2.5 or more. λ2 / λ1 may be 5.0 or less, 4.0 or less, or 3.0 or less. λ2 / λ1 may be 1.2 or more and 4.0 or less, or 1.5 or more and 2.5 or less. In FIG. 5, for the sake of explanation, the thicknesses of the three first unit layers 12 are all indicated as λ1, and the thicknesses of the three second unit layers 15 are all indicated as λ2, but as long as the relationship of λ2 / λ1 is satisfied between the first unit layers and the second unit layers adjacent to each other, the thicknesses λ1 of the three first unit layers 12 do not have to be the same, and the thicknesses λ2 of the three second unit layers 15 do not have to be the same.

[0068] In the first layer 13, the number of layers of each of the first unit layers 12 and the second unit layers 15 may be 5 or more and 500 or less, or may be 10 or more and 500 or less. This makes it possible to fully obtain the effect of improving hardness and compressive residual stress in a well-balanced manner by stacking the first unit layers 12 and the second unit layers 15. In the first layer 13, the number of layers of each of the first unit layers 12 and the second unit layers 15 may be 100 or more and 400 or less, or may be 200 or more and 350 or less.

[0069] In the first layer 13, the number of layers of each of the first unit layers 12 and the second unit layers 15 can be determined by observing a thin sample of the cross section of the coating 3 using a TEM (transmission electron microscope) at a magnification of 20,000 to 5,000,000 times.

[0070] <2nd layer> 3 and 4, the coating 3 further includes a second layer 16 disposed between the substrate 2 and the first layer 13, and the composition of the second layer 16 may be the same as the composition of the first unit layer 12 or the composition of the second unit layer 15. This can increase the adhesion between the substrate 2 and the coating 3.

[0071] When the composition of the second layer 16 is the same as the composition of the first unit layer 12, even if the second layer 16 is exposed at the beginning of cutting, the second layer 16 has good sliding properties, and therefore the wear resistance can be improved.

[0072] When the composition of the second layer 16 is the same as that of the first unit layer 12, the thickness of the second layer 16 may be thicker than that of the first unit layer 12. This can further increase the adhesion between the substrate 2 and the coating 3. In addition, even if the second layer 16 is exposed at the beginning of cutting, the second layer 16 has good sliding properties, so that the wear resistance can be improved. "The thickness of the second layer is thicker than that of the first unit layer" can be rephrased as "The thickness of the second layer is more than 1.0 times the thickness of the first unit layer". The thickness of the second layer 16 may be 2.0 times or more, 4.0 times or more, or 10.0 times or more the thickness of the first unit layer 12. The thickness of the second layer 16 may be 500 times or less, 120 times or less, or 50 times or less the thickness of the first unit layer 12. The thickness of the second layer 16 may be 2.0 times or more and 500 times or less, 4.0 times or more and 120 times or less, or 10.0 times or more and 50 times or less, that of the first unit layer 12 .

[0073] When the composition of the second layer 16 is the same as that of the first unit layer 12, the thickness of the second layer 16 may be 0.1 μm or more. When the thickness of the second layer 16 is less than 0.1 μm, it tends to be difficult to obtain the effect of improving the wear resistance by making the second layer 16 have the same composition as the first unit layer 12. When the composition of the second layer 16 is the same as that of the first unit layer 12, the thickness of the second layer 16 may be 0.3 μm or more, or 0.4 μm or more. There is no particular upper limit to the thickness of the second layer 16, but when it exceeds 2 μm, the crystal grains are enlarged and grain boundaries are generated, so that it tends to be difficult to obtain the effect of improving the wear resistance. Therefore, in consideration of the cost, the thickness of the second layer 16 can be 2 μm or less.

[0074] When the composition of the second layer 16 is the same as the composition of the first unit layer 12, the first unit layer 12 may be laminated directly on the second layer 16, as shown in Fig. 3. Also, the second unit layer 15 may be laminated directly on the second layer 16, as shown in Fig. 4. When the composition of the second layer 16 is the same as the composition of the first unit layer 12 and the first unit layer 12 is laminated directly on the second layer 16, the second layer 16 and the first unit layer 12 have a continuous crystal structure.

[0075] When the composition of the second layer 16 is the same as that of the second unit layer 15, the thickness of the second layer 16 may be thicker than that of the second unit layer 15. This can further increase the adhesion between the substrate 2 and the coating 3. Even if the second layer 16 is exposed at the beginning of cutting, oxidation from the interface between the substrate 2 and the coating 3 can be suppressed and cutting heat can be blocked. "The thickness of the second layer is thicker than that of the second unit layer" can be rephrased as "The thickness of the second layer is more than 1.0 times the thickness of the second unit layer." The thickness of the second layer 16 may be 2.0 times or more, 4.0 times or more, or 10.0 times or more, the thickness of the second unit layer 15. The thickness of the second layer 16 may be 500 times or less, 120 times or less, or 50 times or less, the thickness of the second unit layer 15. The thickness of the second layer 16 may be 2.0 times or more and 500 times or less, 4.0 times or more and 120 times or less, or 10.0 times or more and 50 times or less, the thickness of the second unit layer 15 .

[0076] When the composition of the second layer 16 is the same as that of the second unit layer 15, the thickness of the second layer 16 may be 0.1 μm or more. When the thickness of the second layer 16 is less than 0.1 μm, it tends to be difficult to obtain the effect of suppressing oxidation from the interface between the substrate 2 and the coating 3 and the effect of blocking cutting heat, which are achieved by making the second layer 16 have the same composition as the second unit layer 15. When the composition of the second layer 16 is the same as that of the second unit layer 15, the thickness of the second layer 16 may be 0.3 μm or more, or may be 0.4 μm or more. There is no particular upper limit to the thickness of the second layer 16, but when it exceeds 2 μm, the crystal grains become thick and grain boundaries are generated, which tends to make it difficult to further improve the above-mentioned effect of suppressing oxidation. Therefore, in consideration of the cost, the thickness of the second layer 16 can be 2 μm or less.

[0077] When the composition of the second layer 16 is the same as the composition of the second unit layer 15, the first unit layer 12 may be laminated directly on the second layer 16, as shown in Fig. 3. Also, the second unit layer 15 may be laminated directly on the second layer 16, as shown in Fig. 4. When the composition of the second layer 16 is the same as the composition of the second unit layer 15 and the second unit layer 15 is laminated directly on the second layer 16, the second layer 16 and the second unit layer 15 have a continuous crystal structure.

[0078] <3rd layer> 1 to 4, the coating 3 further includes a third layer 14 provided on the side of the first layer 13 opposite the substrate 2, and the third layer 14 may be made of AlCrCN. This reduces the coefficient of friction of the coating 3, and can extend the life of the cutting tool 1.

[0079] Generally, carbonitrides tend to have a lower coefficient of friction with respect to the work material than nitrides. This reduction in the coefficient of friction is believed to be due to the contribution of carbon atoms. When the coating 3 includes the third layer 14, the coefficient of friction of the coating 3 with respect to the work material is reduced, and the life of the cutting tool 1 is extended.

[0080] In the third layer 14, it is possible to impart a predetermined color by adjusting the composition ratio of N and C. This makes it possible to impart designability and distinctiveness to the appearance of the cutting tool 1, which is commercially useful.

[0081] The thickness of the third layer 14 may be 0.1 μm or more. When the thickness of the third layer 14 is 0.1 μm or more, the lubricity imparting effect of the third layer 14 is easily obtained. On the other hand, although there is no particular upper limit to the thickness of the third layer 14, when it exceeds 2 μm, the above-mentioned lubricity imparting effect tends not to be further improved. Therefore, in consideration of the cost, the thickness of the third layer 14 may be 2 μm or less.

[0082] <Middle Class> The coating 3 may include an intermediate layer disposed between the second layer 16 and the first layer 13, or between the first layer 13 and the third layer 14. Examples of the intermediate layer include AlCrCeN, AlCrN, AlCrBN, AlCrSiN, AlCrYN, AlCrLaN, and the like. The thickness of the intermediate layer may be 0.1 μm or more and 2 μm or less, 0.3 μm or more and 1.5 μm or less, or 0.4 μm or more and 1.0 μm or less.

[0083] [Embodiment 2: Cutting tool (2)] A cutting tool according to another embodiment of the present disclosure will be described with reference to FIGS. A cutting tool 1 according to another embodiment of the present disclosure (hereinafter also referred to as “embodiment 2”) includes: A cutting tool 1 comprising a substrate 2 and a coating 3 disposed on the substrate 2, The coating 3 includes a 1A layer 13A, The 1A layer 13A is composed of alternating layers in which the first unit layers 12 and the third unit layers 17 are alternately laminated, the first unit layer has a hexagonal crystal structure, The first unit layer 12 is made of W(C 1-a N a ) x It consists of: a is equal to or greater than 0.3 and equal to or less than 0.8, x is equal to or greater than 0.8 and equal to or less than 1.2; The third unit layer 17 is made of Al d Cr 1-d-e M e It consists of N, M is silicon, boron, yttrium, cerium or lanthanum; d is equal to or greater than 0.40 and equal to or less than 0.80; e is greater than 0 and is equal to or less than 0.05.

[0084] Embodiment 2 The cutting tool 1 can have a long tool life even in cutting operations performed under conditions where the cutting edge temperature is particularly high. The reason for this is presumably as follows.

[0085] The first unit layer 12 is made of W(C 1-a N a ) x Since the first unit layer 12 contains C (carbon), the friction coefficient at the contact interface with the workpiece is reduced, and the cutting resistance can be reduced. 1-a N a ) x Because it contains N (nitrogen), its heat resistance is improved by about 150°C compared to WC. As a result, the first layer including the first unit layer can improve wear resistance in processes where the cutting edge becomes hot, such as during dry cutting. Therefore, cutting tools including the first layer have an improved tool life.

[0086] When a layer made of nitrides of Al and Cr (hereinafter also referred to as an "AlCrN layer") is compared with a layer made of nitrides containing Al, Cr and M (M is silicon, boron, yttrium, cerium or lanthanum) (hereinafter also referred to as an "AlCrMN layer"), the AlCrMN layer is less susceptible to spinodal decomposition of AlCrN at high temperatures. If spinodal decomposition occurs, soft hexagonal AlN precipitates and hardness decreases. The AlCrMN layer has the properties of suppressing hardness decrease even at high temperatures, large compressive residual stress, and excellent chipping resistance. The AlCrMN layer has the properties of high thermal insulation. The 1A layer 13A is made of W (C 1-a N a ) xSince the first unit layer 13A is composed of alternating layers of the first unit layer 12 made of AlCrMN and the third unit layer 17 made of AlCrMN, it is possible to have the high hardness and low friction coefficient characteristics of the first unit layer 12 and the high heat barrier characteristics of the third unit layer 17. The large compressive residual stress characteristic of the third unit layer 17 is complemented by the small compressive residual stress of the first unit layer 12. Therefore, the hardness, heat barrier characteristics, and compressive residual stress of the 1A layer 13A as a whole are improved in a well-balanced manner, and the life of the cutting tool 1 including the 1A layer 13A is extended.

[0087] The 1A layer 13A is made of alternating layers in which the first unit layers 12 and the third unit layers 17 are alternately laminated. The composition and crystal lattice are discontinuous at the interface between the first unit layers 12 and the third unit layers 17. Therefore, if a crack occurs from the surface of the coating 3 during cutting, the crack can be prevented from progressing at the interface. This prevents chipping and damage, and extends the life of the cutting tool 1.

[0088] The cutting tool 1 of the second embodiment has a first A layer 13A, a second A layer 16 A Except for the configuration of the 3A layer 14A, the configuration can be basically the same as that of the cutting tool 1 of the embodiment 1. The "1A layer", "2A layer" and "3A layer" will be described below.

[0089] <Layer 1A> The 1A layer 13A of this embodiment is composed of alternating layers in which the first unit layers 12 and the third unit layers 17 are alternately laminated. The fact that the 1A layer 13A is composed of alternating layers in which the first unit layers 12 and the third unit layers 17 are alternately laminated can be confirmed by observing the cross section of the coating 3 with a TEM (transmission electron microscope) and observing the difference in contrast. The thickness of the 1A layer 13A can be configured to be the same as that of the first layer 13 described in the first embodiment.

[0090] <Composition of the first unit layer and composition of the third unit layer> Composition W(C 1-a N a ) x is the composition W(C1-a N a ) x can be considered to be the same as

[0091] The third unit layer 17 is made of Al d Cr 1-d-e M e N, M being silicon, boron, yttrium, cerium or lanthanum, d being 0.40 or more and 0.80 or less, and e being more than 0 and 0.05 or less. The third unit layer 17 can have both excellent hardness and excellent oxidation resistance. The reason for this is presumed to be as follows.

[0092] When M is silicon, the structure of the third unit layer 17 becomes finer, and as a result, the hardness and oxidation resistance of the third unit layer 17 improve, and the hardness and oxidation resistance of the entire coating 3 improve.

[0093] When M is boron, the boron increases the hardness of the third unit layer 17, increasing the hardness of the entire coating 3. Also, boron oxide formed by oxidation of the surface of the cutting tool 1 accompanying cutting densifies the Al oxide in the third unit layer 17, improving the oxidation resistance of the third unit layer 17. Furthermore, since boron oxide has a low melting point, it acts as a lubricant during cutting and can suppress adhesion of the workpiece.

[0094] When M is yttrium (Y), cerium (Ce) or lanthanum (La), the lattice constant of YN is 4.88 Å, that of CeN is 5.01 Å, and that of LaN is 5.30 Å. The lattice constants of YN, CeN and LaN are larger than the lattice constant of TiN, 4.23 Å, and that of AlN, 4.12 Å. Therefore, AlN with cubic crystallization due to the addition of Y, Ce, and La has a large lattice constant of 4.88 Å, 5.01 Å, and 5.30 Å, respectively. d Cr 1-d-e M e Strain is introduced into the third unit layer 17 made of N, and the structure becomes finer, so that the hardness and wear resistance of the third unit layer 17 are improved, and the life of the cutting tool 1 including the third unit layer 17 is extended.

[0095] The above d is 0.40 or more and 0.80 or less. This makes the crystal structure of the third unit layer 17 a cubic type, and the third unit layer 17 has high hardness and improves wear resistance. The lower limit of d may be 0.45 or more, 0.50 or more, or 0.55 or more. The upper limit of d may be 0.75 or less, 0.70 or less, or 0.65 or less. d may be 0.45 or more and 0.75 or less, 0.50 or more and 0.70 or less, or 0.55 or more and 0.65 or less.

[0096] The above e is more than 0 and 0.05 or less. This can improve the hardness and oxidation resistance of the 1A layer 13A. The lower limit of e may be 0.002 or more, 0.005 or more, 0.01 or more, or 0.02 or more. The e may be 0.04 or less, or 0.03 or less. The e may be 0.002 or more and 0.05 or less, 0.01 or more and 0.05 or less, 0.01 or more and 0.03 or less, or 0.02 or more and 0.03 or less.

[0097] In the present disclosure, "the third unit layer is Al d Cr 1-d-e M e The term "made of AlN" means that the third unit layer 17 is made of AlN as long as it does not impair the effect of the present disclosure. d Cr 1-d-e M e This means that the third unit layer 17 may contain unavoidable impurities in addition to N. Examples of the unavoidable impurities include oxygen and carbon. The total content of the unavoidable impurities in the third unit layer 17 may be greater than 0 atomic % and less than 1 atomic %.

[0098] The content of d, e, and the inevitable impurities in the third unit layer 17 can be determined by the same method as the measurement method a. 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 same cutting tool 1 is used for the measurement.

[0099] In the present disclosure, the composition W(C 1-a N a ) x In this case, the number of W atoms is A M1The total number of C and N atoms for N1 Ratio of A N1 / A M1 In the present disclosure, the composition Al of the third unit layer is 0.8 or more and 1.2 or less. d Cr 1-d-e M e In N, the total number of Al, Cr and M atoms is A M3 Number of N atoms A N3 Ratio of A N3 / A M3 In manufacturing, the ratio A is necessarily between 0.8 and 1.2. N1 / A M1 and ratio A N3 / A M3 can be measured by the Rutherford backscattering (RBS) method. N1 / A M1 and ratio A N3 / A M3 It has been confirmed that the effect of the present disclosure is not impaired if the amount is within the above range.

[0100] <Average thickness of the first unit layer and the third unit layer> The average thickness of the first unit layer 12 may be 0.002 μm or more and 0.2 μm or less, and the average thickness of the third unit layer 17 may be 0.002 μm or more and 0.2 μm or less. This can further suppress the progression of cracks generated on the surface of the coating 3. The lower limit of the average thickness of the first unit layer 12 may be 0.002 μm or more, 0.005 μm or more, or 0.01 μm or more. The upper limit of the average thickness of the first unit layer 12 may be 0.20 μm or less, 0.15 μm or less, or 0.10 μm or less. The average thickness of the first unit layer 12 may be 0.005 μm or more and 0.15 μm or less, or 0.01 μm or more and 0.1 μm or less. The lower limit of the average thickness of the third unit layer 17 may be 0.002 μm or more, 0.005 μm or more, or 0.01 μm or more. The upper limit of the average thickness of the third unit layer 17 may be 0.20 μm or less, 0.15 μm or less, or 0.10 μm or less. The average thickness of the third unit layer 17 may be 0.005 μm or more and 0.15 μm or less, or 0.01 μm or more and 0.10 μm or less.

[0101] The average thickness of the first unit layer 12 and the average thickness of the third unit layer 17 can be determined by the same method as the method for measuring the thickness of the first layer 13 described above.

[0102] As shown in FIG. 10, in the first unit layer 12 and the third unit layer 17 adjacent to the first unit layer 12, the ratio λ3 / λ1 of the thickness λ3 of the third unit layer 17 to the thickness λ1 of the first unit layer 12 may be 1.0 or more and 5.0 or less. The third unit layer 17 has high oxidation resistance, and has a low thermal conductivity and is difficult to transmit heat generated during cutting to the base material 2. When the ratio λ3 / λ1 is 1.0 or more, the proportion of the third unit layer 17 in the coating 3 relatively increases, and the amount of Al in the coating 3 increases, thereby improving the heat barrier property of the cutting tool 1 as a whole. The cutting tool 1 having the coating 3 has improved wear resistance, especially during continuous cutting. When λ3 / λ1 is 1.0 or more, the toughness of the coating 3 tends to improve. On the other hand, when λ3 / λ1 is 5.0 or less, the effect of suppressing the progress of cracks by laminating the first unit layer 12 and the third unit layer 17 tends to be easily obtained.

[0103] λ3 / λ1 may be 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, or 2.0 or more. λ3 / λ1 may be 5.0 or less, 4.0 or less, or 3.0 or less. λ3 / λ1 may be 1.0 or more and 5.0 or less, 1.2 or more and 4.0 or less, 1.5 or more and 4.0 or less, 1.0 or more and 3.0 or less, or 2.0 or more and 3.0 or less. For the sake of explanation in Figure 10, the thicknesses of all three first unit layers 12 are shown as λ1, and the thicknesses of all three third unit layers 17 are shown as λ3. However, as long as the above-mentioned λ3 / λ1 relationship is satisfied between adjacent first unit layers and third unit layers, the thicknesses λ1 of the three first unit layers 12 do not need to be the same, and the thicknesses λ3 of the three third unit layers 17 do not need to be the same.

[0104] In the 1A layer 13A, the number of layers of each of the first unit layers 12 and the third unit layers 17 may be 4 or more and 800 or less, or may be 10 or more and 500 or less. This tends to make it easier to obtain the effect of improving hardness and compressive residual stress in a well-balanced manner by stacking the first unit layers 12 and the third unit layers 17. In the 1A layer 13A, the number of layers of each of the first unit layers 12 and the third unit layers 17 may be 100 or more and 400 or less, or may be 200 or more and 350 or less.

[0105] In the 1A layer 13A, the number of stacked first unit layers 12 and the number of stacked third unit layers 17 can be determined by a method similar to the method for measuring the number of stacked first unit layers 12 and the number of stacked second unit layers 15 described in embodiment 1.

[0106] <2nd layer> 8 and 9, the coating 3 further includes a 2A layer 16A disposed between the substrate 2 and the 1A layer 13A, and the composition of the 2A layer 16A may be the same as the composition of the first unit layer 12 or the composition of the third unit layer 17. This can increase the adhesion between the substrate 2 and the coating 3.

[0107] When the composition of the second A layer 16A is the same as the composition of the first unit layer 12, even if the second A layer 16A is exposed at the beginning of cutting, the second A layer 16A has good sliding characteristics, and therefore the wear resistance can be improved.

[0108] When the composition of the second A layer 16A is the same as that of the first unit layer 12, the thickness of the second A layer 16A may be thicker than that of the first unit layer 12. This can further increase the adhesion between the substrate 2 and the coating 3. In addition, even if the second A layer 16A is exposed at the beginning of cutting, the second A layer 16A has good sliding properties, so that the wear resistance can be improved. "The thickness of the second A layer is thicker than that of the first unit layer" can be rephrased as "The thickness of the second A layer is more than 1.0 times the thickness of the first unit layer." The thickness of the second A layer 16A may be 2.0 times or more, 4.0 times or more, or 10.0 times or more the thickness of the first unit layer 12. The thickness of the second A layer 16A may be 500 times or less, 120 times or less, or 50 times or less the thickness of the first unit layer 12. The thickness of the second A layer 16A may be 2.0 times or more and 500 times or less, 4.0 times or more and 120 times or less, or 10.0 times or more and 50 times or less, that of the first unit layer 12.

[0109] When the composition of the second A layer 16A is the same as that of the first unit layer 12, the thickness of the second A layer 16A may be 0.1 μm or more. When the thickness of the second A layer 16A is less than 0.1 μm, it tends to be difficult to obtain the effect of improving the wear resistance by making the second A layer 16A the same as that of the first unit layer 12. When the composition of the second A layer 16A is the same as that of the first unit layer 12, the thickness of the second A layer 16A may be 0.3 μm or more, or 0.4 μm or more. Although the upper limit of the thickness of the second A layer 16A is not particularly limited, when it exceeds 2 μm, the crystal grains are enlarged and grain boundaries are generated, so that it tends to be difficult to obtain the effect of improving the wear resistance. Therefore, in consideration of the cost, the thickness of the second A layer 16A can be 2 μm or less.

[0110] When the composition of the 2A layer 16A is the same as that of the first unit layer 12, the first unit layer 12 may be laminated directly on the 2A layer 16A as shown in Fig. 8. Also, the second unit layer 15 may be laminated directly on the 2A layer 16A as shown in Fig. 9. When the composition of the 2A layer 16A is the same as that of the first unit layer 12 and the first unit layer 12 is laminated directly on the 2A layer 16A, the 2A layer 16A and the first unit layer 12 have a continuous crystal structure.

[0111] When the composition of the second A layer 16A is the same as the composition of the third unit layer 17, the third unit layer 17 tends to have a small stress, and therefore the peeling resistance of the coating 3 can be improved, particularly in intermittent machining such as milling and end milling in which loads are repeatedly applied to the cutting edge.

[0112] When the composition of the second A layer 16A is the same as that of the third unit layer 17, the thickness of the second A layer 16A may be thicker than that of the third unit layer 17. This can further increase the adhesion between the substrate 2 and the coating 3. Even if the second A layer 16A is exposed at the beginning of cutting, oxidation from the interface between the substrate 2 and the coating 3 can be suppressed and cutting heat can be blocked. "The thickness of the second A layer is thicker than that of the third unit layer" can be rephrased as "The thickness of the second A layer is more than 1.0 times the thickness of the third unit layer." The thickness of the second A layer 16A may be 2.0 times or more, 4.0 times or more, or 10.0 times or more the thickness of the third unit layer 17. The thickness of the second A layer 16A may be 500 times or less, 120 times or less, or 50 times or less the thickness of the third unit layer 17. The thickness of the second A layer 16A may be 2.0 times or more and 500 times or less, 4.0 times or more and 120 times or less, or 10.0 times or more and 50 times or less, that of the third unit layer 17.

[0113] When the composition of the second A layer 16A is the same as that of the third unit layer 17, the thickness of the second A layer 16A may be 0.1 μm or more. When the thickness of the second A layer 16A is less than 0.1 μm, it tends to be difficult to obtain the effect of suppressing oxidation from the interface between the substrate 2 and the coating 3 and the effect of blocking cutting heat, which are achieved by making the second A layer 16A the same as that of the third unit layer 17. When the composition of the second A layer 16A is the same as that of the third unit layer 17, the thickness of the second A layer 16A may be 0.3 μm or more, or may be 0.4 μm or more. There is no particular upper limit to the thickness of the second A layer 16A, but when it exceeds 2 μm, the crystal grains become thicker and grain boundaries occur, making it difficult to further improve the above-mentioned effect of suppressing oxidation. Therefore, in consideration of the cost, the thickness of the second A layer 16A can be 2 μm or less.

[0114] When the composition of the 2A layer 16A is the same as the composition of the third unit layer 17, the first unit layer 12 may be laminated directly on the 2A layer 16A as shown in Fig. 8. Also, the third unit layer 17 may be laminated directly on the 2A layer 16A as shown in Fig. 9. When the composition of the 2A layer 16A is the same as the composition of the third unit layer 17 and the third unit layer 17 is laminated directly on the 2A layer 16A, the 2A layer 16A and the third unit layer 17 have a continuous crystal structure.

[0115] <3rd layer> 6 to 9, the coating 3 further includes a 3A layer 14A provided on the side of the first layer 13 opposite the substrate 2, and the 3A layer 14A may be made of AlCrMeCN. Here, Me may be silicon, boron, yttrium, cerium, or lanthanum. Me may be the same element as M used in the third unit layer. This can reduce the friction coefficient of the coating 3 and extend the life of the cutting tool 1.

[0116] Generally, carbonitrides tend to have a lower coefficient of friction with respect to the work material than nitrides. This reduction in the coefficient of friction is believed to be due to the contribution of carbon atoms. When the coating 3 includes the 3A layer 14A, the coefficient of friction of the coating 3 with respect to the work material is reduced, and the life of the cutting tool 1 is extended.

[0117] In the 3A layer 14A, it is possible to impart a predetermined color by adjusting the composition ratio of N and C. This makes it possible to impart designability and distinctiveness to the appearance of the cutting tool 1, which is commercially useful.

[0118] The thickness of the 3A layer 14A may be 0.1 μm or more. When the thickness of the 3A layer 14A is 0.1 μm or more, the lubricity imparting effect of the 3A layer 14A is easily obtained. On the other hand, although the upper limit of the thickness of the 3A layer 14A is not particularly limited, if it exceeds 2 μm, the above-mentioned lubricity imparting effect tends not to be further improved. Therefore, in consideration of the cost, the thickness of the 3A layer 14A may be 2 μm or less.

[0119] [Embodiment 3: Manufacturing method of cutting tool] In embodiment 3, a method for manufacturing the cutting tool 1 of embodiment 1 or embodiment 2 will be described. The manufacturing method includes a first step of preparing a substrate 2 and a second step of forming a coating 3 on the substrate 2. The second step includes a step of forming the first layer 13 or the 1A layer 13A. Each step will be described in detail below.

[0120] <1st process> In the first step, a substrate 2 is prepared. As the substrate 2, the substrate 2 described in the first embodiment can be used.

[0121] When a cemented carbide is used as the substrate 2, a commercially available substrate may be used, or the substrate may be manufactured by a general powder metallurgy method. When manufactured by a general powder metallurgy method, WC powder and Co powder are mixed by a ball mill or the like to obtain a mixed powder. The mixed powder is dried and then molded into a predetermined shape to obtain a green body. The green body is then sintered to obtain a WC-Co-based cemented carbide (sintered body). Next, the sintered body is subjected to a predetermined cutting edge processing such as honing to manufacture a substrate made of a WC-Co-based cemented carbide. Substrates other than those mentioned above can also be prepared as long as they are conventionally known as substrates of this type.

[0122] <Second process> In the second step, the coating 3 is formed on the substrate 2. The second step includes a step of forming the first layer 13 or the 1A layer 13A.

[0123] In the "step of forming the first layer", the first unit layer 12 and the second unit layer 15 are alternately laminated by using a physical vapor deposition (PVD) method to form the first layer 13. In the "step of forming the 1A layer", the first unit layer 12 and the third unit layer 17 are alternately laminated by using a PVD method to form the 1A layer 13A. In order to improve the abrasion resistance of the coating 3 including the first layer 13 or the 1A layer 13A, it is effective to form a layer made of a highly crystalline compound. The present inventors have investigated various methods for forming the first layer 13 and the 1A layer 13A, and have found that by using a physical vapor deposition method, a layer made of a highly crystalline compound can be formed, and the coating 3 has excellent abrasion resistance.

[0124] As the PVD method, at least one selected from the group consisting of a cathodic arc ion plating method, a balanced magnetron sputtering method, an unbalanced magnetron sputtering method, and a HiPIMS (High Power Impulse Magnetron Sputtering) method can be used. In particular, the cathodic arc ion plating method, which has a high ionization rate of the raw material element, may be used. When the cathodic arc ion plating method is used, it is possible to perform an ion bombardment treatment of a metal on the surface of the base material 2 before forming the first layer 13 or the 1A layer 13A, so that the adhesion between the base material 2 and the coating 3 including the first layer 13 or the 1A layer 13A is significantly improved.

[0125] The cathodic arc ion plating method can be carried out, for example, by placing a substrate 2 in an apparatus and a target as a cathode, and then applying a high voltage to the target to generate an arc discharge, thereby ionizing and evaporating the atoms that make up the target, and depositing the material on the substrate 2.

[0126] The balanced magnetron sputtering method can be carried out, for example, by placing a substrate 2 in an apparatus, placing a target on a magnetron electrode equipped with a magnet that forms a balanced magnetic field, applying high-frequency power between the magnetron electrode and the substrate 2 to generate a gas plasma, and causing gas ions generated by the generation of this gas plasma to collide with the target, thereby depositing atoms released from the target on the substrate 2.

[0127] The unbalanced magnetron sputtering method can be performed by, for example, unbalancing the magnetic field generated by the magnetron electrodes in the balanced magnetron sputtering method described above. Furthermore, the HiPIMS method can be used, which allows a high voltage to be applied and produces a dense film.

[0128] <Other processes> The second step may include a step of forming the first layer 13 or the first A layer 13A, as well as a step of surface treatment of the coating, such as polishing with a brush, dry or wet shot blasting, etc. The second step may also include a step of forming other layers, such as the second layer 16, the second A layer 16A, the third layer 14, the third A layer 14A, and an intermediate layer. The other layers may be formed by a conventionally known chemical vapor deposition method or physical vapor deposition method. From the viewpoint that the other layers can be formed successively in the first unit layer 12 and the second unit layer 15 or the third unit layer 17 in one physical vapor deposition apparatus, it is preferable to form the other layers by a physical vapor deposition method. EXAMPLES

[0129] The present embodiment will be described more specifically with reference to examples, although the present embodiment is not limited to these examples.

[0130] [Example 1] <Samples 1 to 25, Samples 101 to 106> <Cutting tool manufacturing> FIG. 11 is a schematic cross-sectional view of the cathodic arc ion plating apparatus used in this example, and FIG. 12 is a schematic top view of the apparatus of FIG.

[0131] 11 and 12, a cathode 106 for a first unit layer, a cathode 107 for a second unit layer, and a cathode 120 for a third layer, which are alloy targets serving as the metal raw material of the coating 3, and a rotatable substrate holder 104 for placing a substrate are installed in a chamber 101. The composition of the cathode 106 is adjusted so as to obtain the composition of the first unit layer in Table 1. The composition of the cathode 107 is adjusted so as to obtain the composition of the second unit layer in Table 1. The composition of the cathode 120 is adjusted so as to obtain the composition of the third layer in Table 2.

[0132] An arc power supply 108 is attached to cathode 106, an arc power supply 109 is attached to cathode 107, and an arc power supply (not shown) is attached to cathode 120. A bias power supply 110 is attached to substrate holder 104. A gas inlet 105 through which gas 102 is introduced and a gas outlet 103 are provided in chamber 101 to adjust the pressure in chamber 101, and gas 102 in chamber 101 can be sucked out from gas outlet 103 by a vacuum pump.

[0133] The substrate holder 104 was fitted with a substrate made of cemented carbide of grade JIS P30, and a tip of JIS CNMG120408 and a tip of Sumitomo Electric Hardmetal Corp. SEMT13T3AGSN having a shape conforming to JIS.

[0134] Next, the pressure in the chamber 101 is reduced by the vacuum pump, and the substrate is heated to 500° C. by a heater installed in the apparatus while rotating. The pressure in the chamber 101 is reduced to 1.0×10 -4The chamber was evacuated until the pressure reached 2.0 Pa. Next, argon gas was introduced from the gas inlet to maintain the pressure inside the chamber 101 at 2.0 Pa, and the voltage of the bias power supply 110 was gradually increased to -1000 V to clean the surface of the substrate for 15 minutes. Thereafter, the argon gas was exhausted from the chamber 101 to clean the substrate (argon bombardment treatment). In this manner, the substrate for each sample cutting tool was prepared.

[0135] Next, while rotating the substrate at the center, argon and nitrogen were introduced as reactive gases, and an arc current of 100 A was supplied to the cathodes 106 and 107, respectively, while maintaining the substrate temperature at 400°C, the reactive gas pressure at 3.0 Pa, and the voltage of the bias power supply 110 at a predetermined constant value in the range of -50 V to -200 V. Metal ions were generated from the cathodes 106 and 107, and a second layer having the composition shown in Table 2 and a first layer having the composition shown in Table 1 were formed on the substrate. Here, argon gas was introduced into the first unit layer W(C 1-a N a ) x The purpose of the present invention is to clean the surface of the WC cathode used when forming the nitride film. In the manufacturing method of the present disclosure, the temperature of the substrate is 400°C, which is lower than the conventional nitride film formation temperature of 600°C. The reason is as follows. The present inventors have found that when the substrate temperature is set to 600°C for film formation, the hardness of the film tends to decrease. When the inventors have studied the reason, they have inferred that when the substrate temperature is set to 600°C for film formation, the carbon (C) contained in the cathode for the first unit layer becomes free carbon in the formed film and precipitates. As a result of intensive research, the present inventors have found that by forming the film at a substrate temperature of 400°C, a film that maintains excellent hardness even at high temperatures and has excellent wear resistance can be formed.

[0136] When the second layer was formed, the first layer was formed by alternately stacking the first unit layer and the second unit layer on the second layer, one by one, in the number of layers shown in Table 1. When the second layer was not formed, the first layer was formed by alternately stacking the first unit layer and the second unit layer on the substrate, one by one, in the number of layers shown in Table 1. The thickness of the second layer, and the thickness and number of layers of the first unit layer and the second unit layer in the first layer were adjusted by the rotation speed of the substrate. Then, the current supplied to the evaporation source was stopped when the thicknesses of the second layer and the first layer became the thicknesses shown in Tables 2 and 1, respectively.

[0137] Next, while introducing argon, nitrogen and methane gas as reactive gases into the chamber 101, the temperature of the substrate was maintained at 400°C, the reactive gas pressure was maintained at 2.0 Pa, and the voltage of the bias power supply 110 was maintained at -350 V, and an arc current of 80 A was supplied to the cathode 120 to generate metal ions from the cathode 120 to form a third layer on the first layer. When the thickness of the third layer reached the thickness shown in Table 2, the current supplied to the evaporation source was stopped. The amount of nitrogen introduced and the amount of methane gas introduced were adjusted so that the composition of the third layer in Table 2 was obtained. In this manner, cutting tools of each sample were produced.

[0138] [Table 1]

[0139] [Table 2]

[0140] Evaluation For the cutting tools of each sample, the composition of the first unit layer, the composition of the second unit layer, the composition of the second layer, the composition of the third layer, the number of layers of the first unit layer and the second unit layer, the average thickness of the first unit layer, the average thickness of the second unit layer, the thickness of the first layer, the thickness of the second layer, the thickness of the third layer, λ2 / λ1 and the crystal structure of the first unit layer, and the hardness of the coating were measured.

[0141] <Measurement of the composition of the first unit layer> For each sample cutting tool, the composition of the first unit layer was measured by the method described in embodiment 1, and W(C 1-a N a ) x The values ​​of a and x in the above range were obtained. The results are shown in the "a" and "x" columns of Table 1. In Table 1, "-" in the "a" and "x" columns means that the first unit layer was not present.

[0142] <Measurement of the composition of the second unit layer> For each sample cutting tool, the composition of the second unit layer was measured by the method described in embodiment 1, and Al c Cr 1-c The value of c at N was obtained. The results are shown in the "c" column of Table 1. In Table 1, "-" in the "c" column means that the second unit layer was not present.

[0143] <Measurement of the composition of the second and third layers> For each sample cutting tool, the composition of the second layer and the third layer was determined by the method described in embodiment 1. The results are shown in the "Composition" column of "Second Layer" and the "Composition" column of "Third Layer" in Table 2. "-" in the "Composition" column of "Second Layer" in Table 2 means that the second layer is not present, and "-" in the "Composition" column of "Third Layer" means that the third layer is not present.

[0144] <Measurement of number of layers> For each sample cutting tool, the number of layers of the first unit layers and the number of layers of the second unit layers were determined by the method described in embodiment 1. For example, a number of layers of 10 indicates that the alternating layers include 10 first unit layers and 10 second unit layers. The results obtained are shown in the "Number of layers" column of Table 1.

[0145] <Measurement of the average thickness of the first unit layer, the average thickness of the second unit layer, the thickness of the first layer, the thickness of the second layer, and the thickness of the third layer> For each sample cutting tool, the average thickness of the first unit layer, the average thickness of the second unit layer, the thickness of the first layer, the thickness of the second layer, and the thickness of the third layer were determined by the method described in embodiment 1. The results obtained are shown in the "average thickness [μm]" of the "first unit layer", "average thickness [μm]" of the "second unit layer", "thickness [μm]" of the "first layer" in Table 1, and in the "thickness [μm]" of the "second layer" and "thickness [μm]" of the "third layer" in Table 2. When "-" is written in the "thickness [μm]" column of the "second layer" in Table 2, it means that the second layer does not exist. When "-" is written in the "thickness [μm]" column of the "third layer" in Table 2, it means that the third layer does not exist.

[0146] <λ2 / λ1 measurement> For each sample cutting tool, λ2 / λ1 was determined by the method described in embodiment 1. The results are shown in the "λ2 / λ1" column of Table 1. Note that "-" in the "λ2 / λ1" column of Table 1 means that at least one of the first unit layer and the second unit layer is absent.

[0147] <Measurement of the crystal structure of the first unit layer> For each cutting tool sample, the first unit layer was subjected to XRD measurement to confirm whether the first unit layer had a hexagonal crystal structure. The specific method is as described in embodiment 1. The results are shown in the "Hexagonal Crystal Structure" column of "First Unit Layer" in Table 1. "Yes" indicates that the first unit layer has a hexagonal crystal structure, and "No" indicates that the first unit layer does not have a hexagonal crystal structure. When the crystal structure of the second unit layer was measured, it was confirmed that the second unit layer in all samples contained a cubic crystal structure.

[0148] <Measurement of coating hardness> The hardness of the coating of Samples 1 to 25 was measured by the method described in Embodiment 1. It was confirmed that the hardness of the coating of these samples was within the range of 30 GPa or more and 55 GPa or less.

[0149] <Cutting test 1: Continuous turning test> For each sample CNMG120408-shaped cutting tool, a dry continuous turning test was performed under the following cutting conditions, and the time until the flank wear of the cutting edge reached 0.2 mm was measured. The results are shown in the "Cutting time [min]" column in Table 2. A longer cutting time indicates a longer tool life. ≪Cutting conditions≫ ·Work material: SCM440 (HB=300) ·Cutting speed: 260m / min Feed rate: 0.3mm / rev Depth of cut: 2.0mm Coolant: Dry The cutting process carried out under the above cutting conditions is high-speed, high-efficiency cutting of difficult-to-cut materials, and corresponds to cutting carried out under conditions where the cutting edge temperature is high.

[0150] The cutting tools of Samples 1 to 25 correspond to the Examples, and the cutting tools of Samples 101 to 106 correspond to the Comparative Examples. It was confirmed that the cutting tools of Samples 1 to 25 have a longer tool life in cutting operations performed under conditions of high cutting edge temperatures, compared to the cutting tools of Samples 101 to 106.

[0151] <Cutting test 2: Milling test> For each sample cutting tool with a SEMT13T3AGSN shape, the center line of a 150 mm wide plate made of a hard-to-cut material was aligned with the center of a wider cutter with a diameter of 160 mm, and surface milling was performed under the following cutting conditions, and the cutting length until the flank wear of the cutting edge reached 0.2 mm was measured. The results are shown in the "Cutting length [km]" column in Table 2. A longer cutting length indicates a longer tool life. ≪Cutting conditions≫ ·Work material: SKD11 (HB=235) ·Cutting speed: 190m / min Feed rate: 0.15mm / t Axial depth of cut ap: 1.5mm Radial cutting depth ae: 150mm Coolant: Dry The cutting process carried out under the above cutting conditions is high-speed, high-efficiency milling of difficult-to-cut materials under dry conditions, and corresponds to cutting carried out under conditions where the cutting edge temperature is high.

[0152] The cutting tools of Samples 1 to 25 correspond to the Examples, and the cutting tools of Samples 101 to 106 correspond to the Comparative Examples. It was confirmed that the cutting tools of Samples 1 to 25 have a longer tool life in cutting operations performed under conditions of high cutting edge temperatures, compared to the cutting tools of Samples 101 to 106.

[0153] [Example 2] <Samples 51 to 85, Samples 151 to 176> <Cutting tool manufacturing> The substrate of each sample was prepared in the same manner as in Example 1. With the substrate rotated at the center, argon and nitrogen were introduced as reactive gases while maintaining the substrate temperature at 450°C, the reactive gas pressure at 2.0 Pa, and the voltage of the bias power supply 110 at a predetermined constant value in the range of -50V to -200V. An arc current of 100A was supplied to the cathodes 106 and 107, respectively, to generate metal ions from the cathodes 106 and 107, thereby forming the 2A layer and the 1A layer having the compositions shown in Tables 3 to 6 on the substrate. The composition of the cathode 106 was adjusted so that the composition of the 1st unit layer in Tables 3 to 4 was obtained. The composition of the cathode 107 was adjusted so that the composition of the 3rd unit layer in Tables 3 to 4 was obtained. The composition of the cathode 120 was adjusted so that the composition of the 3A layer in Tables 5 to 6 was obtained. In the manufacturing method of the present disclosure, the temperature of the substrate was 450°C, which is lower than the conventional nitride film formation temperature of 600°C. The reason for this is as follows. The inventors have found that when the film is formed at a substrate temperature of 600°C, the hardness of the film tends to decrease. After studying the reason for this, it was inferred that when the film is formed at a substrate temperature of 600°C, the carbon (C) contained in the cathode for the first unit layer becomes free carbon in the formed film and precipitates. As a result of extensive research, the inventors have found that a film that maintains excellent hardness even at high temperatures and has excellent wear resistance can be formed by forming the film at a substrate temperature of 450°C.

[0154] When the 2A layer was formed, the 1A layer was formed by alternately stacking the first unit layer and the third unit layer on the 2A layer, one by one, in the number of layers shown in Tables 3 to 4. When the 2A layer was not formed, the 1A layer was formed by alternately stacking the first unit layer and the third unit layer on the substrate, one by one, in the number of layers shown in Tables 3 to 4. The thickness of the 2A layer, and the thickness and number of layers of the first unit layer and the third unit layer in the 1A layer were adjusted by the rotation speed of the substrate. Then, the current supplied to the evaporation source was stopped when the thicknesses of the 2A layer and the 1A layer reached the thicknesses shown in Tables 3 to 6, respectively.

[0155] Next, while introducing argon, nitrogen and methane gas as reactive gases into the chamber 101, the temperature of the substrate was maintained at 350°C, the reactive gas pressure was maintained at 2.0 Pa, and the voltage of the bias power supply 110 was maintained at -350 V, and an arc current of 100 A was supplied to the cathode 120 to generate metal ions from the cathode 120 to form a 3A layer on the 1A layer. When the thickness of the 3A layer reached the thickness shown in Tables 5 and 6, the current supplied to the evaporation source was stopped. The amount of nitrogen introduced and the amount of methane gas introduced were adjusted so that the composition of the 3A layer shown in Tables 5 and 6 was obtained. In this manner, cutting tools of each sample were manufactured.

[0156] [Table 3]

[0157] [Table 4]

[0158] [Table 5]

[0159] [Table 6]

[0160] Evaluation For the cutting tools of each sample, the composition of the first unit layer, the composition of the third unit layer, the composition of the second A layer, the composition of the third A layer, the number of layers of the first unit layer and the third unit layer, the average thickness of the first unit layer, the average thickness of the third unit layer, the thickness of the first A layer, the thickness of the second A layer, the thickness of the third A layer, λ3 / λ1 and the crystal structure of the first unit layer, and the hardness of the coating were measured. The measurement method for each item was as described in Example 1. The results are shown in Tables 3 to 6.

[0161] <Measurement of coating hardness> The hardness of the coating of Samples 51 to 85 was measured by the method described in embodiment 1. It was confirmed that the hardness of the coating of these samples was within the range of 30 GPa or more and 55 GPa or less.

[0162] <Cutting test 3: Continuous turning test> For each sample of cutting tools with a CNMG120408 shape, a dry continuous turning test was performed under the following cutting conditions, and the time until the flank wear of the cutting edge reached 0.2 mm was measured. The results are shown in the "Cutting time [min]" column of Tables 5 and 6. In Tables 5 and 6, a longer cutting time indicates a longer tool life. (Cutting conditions) ·Cutting material: Inconel 718 (aged material: HB=400) ·Cutting speed: 70m / min Feed rate: 0.15mm / rev Depth of cut: 1.0mm Coolant: Dry The cutting process carried out under the above cutting conditions is high-speed, high-efficiency cutting of difficult-to-cut materials, and corresponds to cutting carried out under conditions where the cutting edge temperature is high.

[0163] The cutting tools of Samples 51 to 85 correspond to the Examples, and the cutting tools of Samples 151 to 176 correspond to the Comparative Examples. It was confirmed that the cutting tools of Samples 51 to 85 have a longer tool life in cutting operations performed under conditions of high cutting edge temperatures, compared to the cutting tools of Samples 151 to 176.

[0164] <Cutting test 4: Milling test> For each sample cutting tool with a SEMT13T3AGSN shape, the center line of a 150 mm wide plate made of a hard-to-cut material was aligned with the center of a wider cutter with a diameter of 160 mm, and surface milling was performed under the following cutting conditions, and the cutting length until the flank wear of the cutting edge reached 0.2 mm was measured. The results are shown in the "Cutting Length [km]" column in Tables 5 and 6. Note that in Tables 5 and 6, a longer cutting length indicates a longer tool life. ≪Cutting conditions≫ ·Work material:FCD700(HB=250) ·Cutting speed: 260m / min Feed rate: 0.2mm / t Axial depth of cut ap: 2.0mm Radial cutting depth ae: 150mm Coolant: Dry The cutting process carried out under the above cutting conditions is high-speed, high-efficiency milling of difficult-to-cut materials under dry conditions, and corresponds to cutting carried out under conditions where the cutting edge temperature is high.

[0165] The cutting tools of Samples 51 to 85 correspond to the Examples, and the cutting tools of Samples 151 to 176 correspond to the Comparative Examples. It was confirmed that the cutting tools of Samples 51 to 85 have a longer tool life in cutting operations performed under conditions of high cutting edge temperatures, compared to the cutting tools of Samples 151 to 176.

[0166] Although the embodiments and examples of the present disclosure have been described above, it is intended from the outset that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways. The embodiments and examples disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is indicated by the claims, not by the embodiments and examples described above, and is intended to include the meaning equivalent to the claims and all modifications within the scope. [Explanation of symbols]

[0167] 1 cutting tool, 2 substrate, 3 coating, 12 first unit layer, 13 first layer, 13A first A layer, 14 third layer, 14A third A layer, 15 second unit layer, 16 second layer, 16A second A layer, 17 third unit layer, 101 chamber, 102 gas, 103 gas exhaust port, 104 substrate holder, 105 gas inlet port, 106, 107, 120 cathode, 108, 109 arc power supply, 110 bias power supply.

Claims

1. 1. A cutting tool comprising a substrate and a coating disposed on the substrate, The coating comprises a first layer, The first layer is composed of alternating layers in which first unit layers and second unit layers are alternately laminated, the first unit layer has a hexagonal crystal structure, The first unit layer is W(C １－ａ N ａ ) ｘ It consists of: The a is 0.3 or more and 0.8 or less, The x is 0.8 or more and 1.2 or less, The second unit layer is Al ｃ Cr １－ｃ It consists of N, The cutting tool, wherein c is equal to or greater than 0.40 and equal to or less than 0.

80.

2. The cutting tool according to claim 1, wherein, in the first unit layer and the second unit layer adjacent to the first unit layer, a ratio λ2 / λ1 of a thickness λ2 μm of the second unit layer to a thickness λ1 μm of the first unit layer is 1.0 or more and 5.0 or less.

3. The first unit layer has an average thickness of 0.002 μm or more and 0.2 μm or less, The cutting tool according to claim 1 or 2, wherein an average thickness of the second unit layer is not less than 0.002 μm and not more than 0.2 μm.

4. The coating further includes a second layer disposed between the substrate and the first layer; The cutting tool according to claim 1 or 2, wherein a composition of the second layer is the same as a composition of the first unit layer or a composition of the second unit layer.

5. the composition of the second layer is the same as the composition of the first unit layer; The cutting tool according to claim 4 , wherein the second layer has a thickness greater than a thickness of the first unit layer.

6. the composition of the second layer is the same as the composition of the second unit layer; The cutting tool according to claim 4 , wherein the second layer has a thickness greater than a thickness of the second unit layer.

7. The coating further includes a third layer provided on a side of the first layer opposite the substrate, The cutting tool according to claim 1 or 2, wherein the third layer is made of AlCrCN.

8. 1. A cutting tool comprising a substrate and a coating disposed on the substrate, The coating comprises a first A layer, The first A layer is composed of alternating layers in which first unit layers and third unit layers are alternately laminated, the first unit layer has a hexagonal crystal structure, The first unit layer is W(C １－ａ N ａ ) ｘ It consists of: The a is 0.3 or more and 0.8 or less, The x is 0.8 or more and 1.2 or less, The third unit layer is Al ｄ Cr １－ｄ－ｅ M ｅ It consists of N, M is silicon, boron, yttrium, cerium or lanthanum; The d is 0.40 or more and 0.80 or less, The cutting tool, wherein e is greater than 0 and is 0.05 or less.

9. The cutting tool according to claim 8, wherein, in the first unit layer and the third unit layer adjacent to the first unit layer, a ratio λ3 / λ1 of a thickness λ3 μm of the third unit layer to a thickness λ1 μm of the first unit layer is 1.0 or more and 5.0 or less.

10. The cutting tool according to claim 8 or 9, wherein M is silicon.

11. The cutting tool according to claim 8 or claim 9, wherein M is boron.

12. The first unit layer has an average thickness of 0.002 μm or more and 0.2 μm or less, The cutting tool according to claim 8 or 9, wherein an average thickness of the third unit layer is not less than 0.002 μm and not more than 0.2 μm.

13. The coating further includes a second A layer disposed between the substrate and the first A layer; The cutting tool according to claim 8 or 9, wherein a composition of the second A layer is the same as a composition of the first unit layer or a composition of the third unit layer.

14. The composition of the second A layer is the same as the composition of the first unit layer, The cutting tool according to claim 13 , wherein the second A layer has a thickness greater than a thickness of the first unit layer.

15. The composition of the second A layer is the same as the composition of the third unit layer, The cutting tool according to claim 13 , wherein the second A layer has a thickness greater than a thickness of the third unit layer.

16. The coating further includes a third A layer provided on the side of the first A layer opposite the substrate, the third A layer is made of AlCrMeCN, The cutting tool according to claim 8 or claim 9, wherein Me is silicon, boron, yttrium, cerium or lanthanum.

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