Cutting tool

Abstract

A cutting tool provided with a base material and a coating film disposed on the base material, the coating film including a first layer comprising an alternating layer in which first unit layers and second unit layers are alternately laminated, the first unit layers comprising Ti1-aMoaN, where a is 0.01-0.20, the second unit layers comprising AlbV1-bN, where a is 0.01-0.20, the first unit layers comprising Ti1-aMoaN, and the second unit layers comprising AlbV1-bN, where a is 0.01-0.20. And b is greater than or equal to 0.40 and less than or equal to 0.80.

Description

TECHNICAL FIELD

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

[0002] Conventionally, a cutting tool provided with a base material and a coating film arranged on the base material is used for cutting processing (Patent Document 1).

[0003] PRIOR ART DOCUMENT PATENT DOCUMENT Patent Document 1: Japanese Patent Application Laid-Open No. 2022-512808 SUMMARY

[0004] The cutting tool of the present disclosure is provided with a base material and a coating film arranged on the base material, wherein the coating film includes a first layer, the first layer is composed of an alternating layer in which a first unit layer and a second unit layer are alternately stacked, the first unit layer is composed of Ti 1-a Mo a N, the a is 0.01 or more and 0.20 or less, the second unit layer is composed of Al b V 1-b N, the b is 0.40 or more and 0.80 or less. BRIEF DESCRIPTION OF DRAWINGS

[0005] Figure 1 is an enlarged schematic sectional view of one example of the cutting tool according to Embodiment 1.

[0006] Figure 2 is an enlarged schematic sectional view of another example of the cutting tool according to Embodiment 1.

[0007] Figure 3 is an enlarged schematic sectional view of another example of the cutting tool according to Embodiment 1.

[0008] Figure 4 is an enlarged schematic sectional view of another example of the cutting tool according to Embodiment 1.

[0009] Figure 5 is a view for explaining one example of a ratio of thicknesses of the first unit layer and the second unit layer.

[0010] Figure 6 is an enlarged schematic sectional view of one example of the cutting tool according to Embodiment 2.

[0011] Figure 7This is a schematic enlarged cross-sectional view of another example of the cutting tool involved in Embodiment 2.

[0012] Figure 8 This is a schematic enlarged cross-sectional view of another example of the cutting tool involved in Embodiment 2.

[0013] Figure 9 This is a schematic enlarged cross-sectional view of another example of the cutting tool involved in Embodiment 2.

[0014] Figure 10 This is a diagram used to illustrate an example of the thickness ratio of the first unit layer and the third unit layer.

[0015] Figure 11 This is a schematic cross-sectional view of the cathode arc ion plating apparatus used in the embodiment.

[0016] Figure 12 yes Figure 11 A schematic top view of the cathode arc ion plating apparatus shown. Detailed Implementation

[0017] [The problem this disclosure aims to solve] In recent years, carbon offsetting measures have been accelerating both domestically and internationally against the backdrop of rapid global warming. Domestically, in order to achieve carbon offsetting by 2050, the manufacturing industry, especially the metal processing sector, is pursuing a reduction in CO2 emissions from the perspective of environmental performance, building upon current quality, processing efficiency, and cost considerations.

[0018] In metal cutting processes, the majority of electricity is consumed due to the preparation of hydraulic and pneumatic units and auxiliary equipment, as well as the circulation and supply of coolant (cutting oil), compared to the spindle rotation and feed drive of the machining machine. Therefore, as a countermeasure for energy saving, in addition to improving the efficiency of motors and auxiliary equipment, measures include the use of inverter-controlled hydraulic units, optimal operation control of hydraulic and pneumatic systems, and chip conveyors (chip handling). Furthermore, in recent years, coolant-free technology (dry machining) or semi-dry technology that mists the coolant has gained attention. These technologies can reduce waste by reducing coolant usage and further reduce the electricity required for coolant use. Therefore, further advancements in these energy-saving technologies are anticipated.

[0019] In the past, dry machining involved exploring the application of various cutting tools and researching optimal machining conditions for different workpiece materials. Dry machining was sometimes also performed on non-ferrous metals and cast iron. On the other hand, there is a high demand for dry machining of workpiece materials such as general steel and ultra-heat-resistant alloys, which are considered difficult to machine. However, the current situation is that dry machining is also facing challenges, and the development of new tool materials is underway.

[0020] As a type of coating tool material, nitride films with aluminum (Al) and vanadium (V) as the main components have been proposed (Patent Document 1). From the perspective of CO2 reduction and environmental protection, and based on the requirements for dry machining without cutting oils, the increasing cutting speeds to improve machining efficiency, and the diversification of materials being cut, especially the increasing cutting of heat-resistant alloys and titanium alloys, which are considered difficult-to-cut materials in the fields of aerospace and medicine, there is a tendency for the tip temperature of cutting tools to become high. If the tip temperature becomes high, the tool life becomes extremely short. Therefore, there is a need for cutting tools that can exhibit excellent tool life even under such harsh cutting conditions.

[0021] [Effects of this disclosure] According to this disclosure, a cutting tool with a long tool life can be provided, especially in cutting operations performed under conditions of high tool tip temperature.

[0022] [Description of embodiments of this disclosure] The embodiments of this disclosure will be described first.

[0023] (1) The cutting tool of this disclosure comprises a substrate and a coating disposed on the substrate, wherein, The coating comprises a first layer. The first layer is composed of alternating layers of first unit layers and second unit layers. The first unit layer consists of Ti 1-a Mo a N constitutes, The value of a is greater than 0.01 and less than 0.20. The second unit layer consists of Al b V 1-b N constitutes, The value of b is greater than 0.40 and less than 0.80.

[0024] According to this disclosure, a cutting tool with a long tool life can be provided, especially in cutting operations performed under conditions of high tool tip temperature.

[0025] (2) Based on (1) above, the ratio of the thickness λ2μm of the second unit layer to the thickness λ1μm of the first unit layer in the first unit layer and the second unit layer adjacent to the first unit layer may be λ2 / λ1 of 1.0 or more and 5.0 or less. As a result, the cutting tool can have a longer tool life.

[0026] (3) Based on (1) or (2) above, it can also be that, The average thickness of the first unit layer is greater than 0.002 μm and less than 0.2 μm. The average thickness of the second unit layer is greater than 0.002 μm and less than 0.2 μm.

[0027] As a result, cutting tools can have a longer tool life.

[0028] (4) Based on any one of (1) to (3) above, it can also be that, The coating further includes a surface layer disposed on the side of the first layer opposite to the substrate. The surface layer is composed of TiMoON or AlVON.

[0029] As a result, cutting tools can have a longer tool life.

[0030] (5) The cutting tool of this disclosure comprises a substrate and a coating disposed on the substrate, wherein, The coating comprises a second layer. The second layer consists of alternating layers formed by alternating stacks of the first unit layer and the third unit layer. The first unit layer consists of Ti 1-a MO a N constitutes, The value of a is greater than 0.01 and less than 0.20. The third unit layer is composed of Al c V 1-c-d X d N constitutes, X is selected from one or two of the group consisting of boron, silicon, scandium, yttrium, and cerium. The value of c is greater than 0.40 and less than 0.80. The value of d is greater than or equal to 0.001 and less than or equal to 0.05.

[0031] According to this disclosure, a cutting tool with a long tool life can be provided, especially in cutting operations performed under conditions of high tool tip temperature.

[0032] (6) Based on (5) above, it is also possible that, in the first unit layer and the third unit layer adjacent to the first unit layer, the ratio of the thickness λ3μm of the third unit layer to the thickness λ1μm of the first unit layer, λ3 / λ1, is 1.0 or more and 5.0 or less. As a result, the cutting tool can have a longer tool life.

[0033] (7) Based on (5) or (6) above, it could also be that, The average thickness of the first unit layer is greater than 0.002 μm and less than 0.2 μm. The average thickness of the third unit layer is greater than 0.002 μm and less than 0.2 μm.

[0034] As a result, cutting tools can have a longer tool life.

[0035] (8) Based on any one of (5) to (7) above, it can also be that, The coating further includes a surface layer disposed on the side of the second layer opposite to the substrate. The surface layer is composed of TiMoON or AlVXON. X is selected from one or two of the group consisting of boron, silicon, scandium, yttrium, and cerium.

[0036] As a result, cutting tools can have a longer tool life.

[0037] [Details of the embodiments disclosed herein] Specific examples of the cutting tools of this disclosure will be described below with reference to the accompanying drawings. In the drawings of this disclosure, the same reference numerals denote the same or equivalent parts. In addition, dimensional relationships such as length, width, thickness, and depth have been appropriately modified for the clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0038] In this disclosure, the expression "A~B" means that A is above and B is below, and where there is no unit recorded in A but only in B, the unit of A is the same as the unit of B.

[0039] In this disclosure, when compounds are represented by chemical formulas, all previously known atomic ratios are included without specifically limiting the atomic ratios, and are not necessarily limited to atomic ratios within the stoichiometric range.

[0040] In this disclosure, when more than one value is recorded as the lower limit and the upper limit of the numerical range, it is believed that a combination of any value recorded in the lower limit and any value recorded in the upper limit is also disclosed.

[0041] [Implementation Method 1: Cutting Tool (1)] use Figures 1-5 A cutting tool according to one embodiment of this disclosure will be described.

[0042] One embodiment of this disclosure (hereinafter also referred to as "Embodiment 1") involves a cutting tool 1 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 formed by alternating stacking of the first unit layer 12 and the second unit layer 15. The first unit layer 12 consists of Ti 1-a Mo a N constitutes, a is greater than 0.01 and less than 0.20. The second unit layer 15 consists of Al b V 1-b N constitutes, b is greater than 0.40 and less than 0.80.

[0043] The cutting tool of Embodiment 1 can have a long tool life, especially in cutting operations performed under conditions of high tool tip temperature. The reason for this is speculated as follows.

[0044] The first unit layer consists of Ti 1-a Mo a The material is composed of nitrogen (N). The first unit layer contains molybdenum (Mo), which is oxidized during cutting to form MoO3, an oxide of Mo. Since MoO3 has a melting point of 795°C, it softens at the temperature during cutting and functions as a lubricant, reducing the coefficient of friction on the tool rake face. As a result, the first layer containing the first unit layer improves resistance to adhesion, slippage, and wear during machining processes where the tool tip becomes hot, such as dry cutting.

[0045] The second unit layer consists of Al b V 1-b The first layer is composed of nitrogen (N). The second unit layer contains Al. Since Al is easily oxidized, the coating containing the second unit layer tends to form a dense oxide layer of Al₂O₃ on the surface side of the first layer. As a result, the thermal barrier properties and oxidation resistance of the first layer can be improved.

[0046] The second unit layer is oxidized during cutting, generating V₂O₅, which is an oxide of V. Since V₂O₅ has a melting point of 690°C, it softens at the temperature during cutting and functions as a lubricant, thereby reducing the coefficient of friction on the tool rake face.

[0047] The first layer consists of alternating layers of first and second unit layers. At the interface between the first and second unit layers, the composition and lattice are discontinuous. Therefore, in the event of cracks forming on the surface of the coating during cutting, crack propagation can be suppressed at the interface. In a coating containing the first layer, chipping and defects are suppressed.

[0048] Based on the above, the tool life of cutting tools consisting of alternating layers formed by alternating layers of first and second unit layers is improved.

[0049] <Cutting Tools> like Figure 1 as well as Figure 2 As shown, a cutting tool 1 according to one embodiment of the present invention includes a substrate 2 and a coating 3 disposed on the substrate 2. The coating 3 is capable of covering at least the cutting portion of the substrate 2. The coating 3 may also cover the entire surface of the substrate 2. Even if the composition of the coating 3 is partially different, it will not depart from the scope of this embodiment. In this disclosure, the cutting portion of the substrate 2 refers to the area on the surface of the substrate 2 at a distance of at least 50 μm, 100 μm, or 300 μm from the cutting edge.

[0050] The cutting tool of Embodiment 1 can preferably be used as a drill bit, end mill, indexable cutting insert for drill bit, indexable cutting insert for end mill, indexable cutting insert for milling, indexable cutting insert for turning, metalworking saw, gear cutting tool, reamer, tap, and other cutting tools.

[0051] <Substrate> As for the substrate, any previously known substrate can be used. For example, the substrate can be composed of any of the following: cemented carbide (WC-based cemented carbide, cemented carbide containing WC and Co, cemented carbide with carbonitrides such as Ti, Ta, and Nb added to WC and Co), cermet (cermet with TiC, TiN, TiCN, etc. as the main components), high-speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, alumina, etc.), cubic boron nitride sintered body, or diamond sintered body.

[0052] In particular, the substrate can also be WC-based cemented carbide or cermet (especially TiCN-based cermet). WC-based cemented carbide or cermet, especially at high temperatures, has an excellent balance between hardness and strength, and therefore can contribute to the long service life of cutting tools when used as a substrate.

[0053] <Lamination> In the cutting tool of Embodiment 1, the coating includes a first layer. By covering the substrate, the coating improves various properties of the cutting tool, such as wear resistance and chipping resistance, thereby extending the tool's lifespan.

[0054] In addition to the first layer, the coating can also include other layers. For example... Figure 3 as well as Figure 4 As shown, other layers may include a base layer 16 disposed between the substrate 2 and the first layer 13, and a surface layer 14 disposed on the side of the first layer 13 opposite to the substrate 2.

[0055] The overall thickness of the coating can be 0.4 μm or more and 15 μm or less. If the overall thickness of the coating is 0.4 μm or more, it is easy to achieve the effect of extending the life of the cutting tool by setting the coating. On the other hand, if the overall thickness of the coating is 15 μm or less, it is less likely to cause cracking at the coating site in the early stages of cutting, which can extend the life of the cutting tool.

[0056] The overall thickness of the coating can be determined by observing the cross-section of the coating using a scanning electron microscope (SEM). A cutting tool is used to prepare a cross-sectional sample by cutting along the normal direction of the coating surface. The cross-sectional sample is then observed using SEM. The magnification is set to 5000–10000x, and the measurement field of view is set to 100–500 μm. 2 The thickness of the coating is measured at three locations within a single field of view, and the average thickness of the three locations is calculated. This average value corresponds to the overall thickness of the coating. The thicknesses of the layers described later are measured using the same method unless otherwise specified.

[0057] The absolute value of the compressive residual stress of the coating can be 6 GPa or less. The compressive residual stress of the coating refers to a type of internal stress (inherent strain) existing throughout the coating, and is expressed as a negative value (unit: GPa in this embodiment). Therefore, a large compressive residual stress indicates a large absolute value, while a small compressive residual stress indicates a small absolute value. That is, an absolute value of 6 GPa or less means that the compressive residual stress of the coating 3 is between -6 GPa and 0 GPa.

[0058] If the compressive residual stress of the coating is below 0 GPa, the propagation of cracks originating from the outermost surface of the coating can be easily suppressed. On the other hand, if the absolute value of the compressive residual stress is below 6 GPa, the stress is moderate, and it is easy to prevent the coating from peeling off from the edge of the cutting tool before cutting begins.

[0059] The compressive residual stress of the coating was determined using an X-ray residual stress analyzer via sin2 The X-ray stress measurement was performed using the ψ method (see pages 54-66 of the Japan Materials Society, published by Yokendo Co., Ltd. in 1981).

[0060] The coating exhibits good performance when its hardness is above 30 GPa and below 55 GPa, or even above 35 GPa and below 50 GPa. This indicates that the coating possesses sufficient hardness. The overall hardness of the coating was determined using a nanoindenter (MTS Nano Indenter XP). Specifically, following the method described in ISO 14577, the test load was set to 10 mN (1 gf), and the hardness of three locations on the surface of coating 3 was measured. The average hardness of the three locations was calculated. This average value represents the hardness of coating 3.

[0061] <First Layer> In the cutting tool of Embodiment 1, the first layer is composed of alternating layers of first unit layers and second unit layers. This configuration of the first layer being composed of alternating layers of first unit layers and second unit layers can be confirmed by observing a thin sheet sample containing the coating section using a TEM (transmission electron microscope) and by observing the contrast difference.

[0062] Either the first unit layer or the second unit layer can be positioned closest to the substrate side. Figure 1 In this configuration, a first unit layer 12 is disposed directly above the substrate 2. Figure 2 In this structure, a second unit layer 15 is disposed directly above the substrate 2. Either the first unit layer 12 or the second unit layer 15 can be disposed on the surface side of the coating 3. Figure 1 In this process, a second unit layer 15 is disposed on the surface side of the coating 3. Figure 2 In the middle, a first unit layer 12 is disposed on the surface side of the coating 3.

[0063] The thickness of the first layer can be 0.5 μm or more and 15 μm or less, 2 μm or more and 15 μm or less, or 5 μm or more and 10 μm or less. If the thickness of the first layer is 0.5 μm or more, it can exhibit excellent wear resistance in continuous machining. If the thickness of the first layer 13 is 15 μm or less, it can exhibit excellent resistance to chipping in interrupted cutting.

[0064] The thickness of the first layer can be determined by observing the cross-section of the coating using a transmission electron microscope (TEM). A cutting tool is used to cut along the normal direction of the coating surface to prepare a thin-section sample containing the cross-section. The thin-section sample is then observed using TEM. The magnification is set to 20,000–5,000,000x, and the measurement field of view is set to 0.0016–80 μm. 2The thickness of the first layer is measured at three locations within a single field of view, and the average thickness of these three locations is calculated. This average value corresponds to the thickness of the first layer.

[0065] The first unit layer can have a cubic crystal structure. If the first unit layer has a cubic crystal structure, the wear resistance of the coating is improved. The second unit layer can contain a cubic crystal structure. If the second unit layer has a cubic crystal structure, the hardness of the coating is improved. The crystal structure of each layer in the coating can be determined using X-ray diffraction equipment known in the art.

[0066] As an example of an apparatus for X-ray diffraction measurement, the "SmartLab" (trade name) manufactured by Rigaku Co., Ltd. can be cited. The conditions for X-ray diffraction measurement are as follows.

[0067] (XRD measurement conditions) Scan axis: 2θ-θ X-ray source: Cu-Kα line (1.541862 Å) Detector: Zero-dimensional detector (scintillation counter) Tube voltage: 45kV Tube current: 40mA Incident optical systems: the use of mirrors Optical system for receiving light: Utilization of analyzer crystal (PW3098 / 27) Step size: 0.03° Total time: 2 seconds Scan range (2θ): 10°~120° <The composition of the first unit layer and the composition of the second unit layer> The first unit layer consists of Ti 1-a Mo a N is the component, and a is 0.01 or higher and 0.20 or lower. a can be 0.03 or higher and 0.18 or lower, 0.05 or higher and 0.15 or lower, or 0.08 or higher and 0.14 or lower.

[0068] In this disclosure, "the first unit layer is composed of Ti" 1-a Mo a "N composition" means that, as long as the effect of this disclosure is not impaired, the first unit layer can be in Ti 1-a Mo a The N-based system contains unavoidable impurities. Examples of unavoidable impurities include, for instance, oxygen and carbon. The overall content of unavoidable impurities in the first unit layer can be greater than 0 atomic percent and less than 1 atomic percent.

[0069] The second unit layer consists of Alb V 1-b N is the component, and b is 0.40 or higher and 0.80 or lower. b can be 0.45 or higher and 0.75 or lower, 0.50 or higher and 0.70 or lower, or 0.55 or higher and 0.65 or lower.

[0070] In this disclosure, "the second unit layer is composed of Al" b V 1-b "N configuration" means that, as long as the effect of this disclosure is not impaired, the second unit layer 15 can be in A1 b V 1-b The N-based structure contains unavoidable impurities. Examples of unavoidable impurities include, for instance, oxygen and carbon. The overall content of unavoidable impurities in the second unit layer can be greater than 0 atomic percent and less than 1 atomic percent.

[0071] The contents of a, b, and the unavoidable impurities in the first and second unit layers were determined by elemental analysis of the cross-section of the coating using a transmission electron microscope (TEM). A thin-film sample containing the cross-section of the coating was prepared by cutting a cutting tool along the normal direction of the coating surface. The thin-film sample was irradiated with an electron beam using an EDS (Energy Dispersive X-ray Spectroscopy) instrument attached to the TEM, and the energy and number of characteristic X-rays generated were measured to perform elemental analysis of the first and second unit layers. Five first and five second unit layers were randomly selected for elemental analysis. The average composition of the five first unit layers was determined. This average composition corresponds to the composition of the first unit layer. The average composition of the five second unit layers was determined. This average composition corresponds to the composition of the second unit layer. When the number of first and second unit layers was four or less, elemental analysis was performed on all layers to determine the average composition of the first and second unit layers. It was confirmed that as long as the measurement is performed using the same cutting tool, the measurement results will not deviate even if the measurement location is arbitrarily selected.

[0072] In this disclosure, the composition Ti of the first unit layer 1-a Mo a In N, the number of N atoms A N1 The total number of atoms A relative to Ti and Mo M1 The ratio A N1 / A M1 It is above 0.8 and below 1.2. In this disclosure, the composition Al of the second unit layer... b V 1-b In N, the number of N atoms A N2 The total number of atoms A relative to Al and VM2 The ratio A N2 / A M2 It is above 0.8 and below 1.2. Compared to A N1 / A M1 And compared to A N2 / A M2 It can be determined using the Rutherford backscattering (RBS) method. It has been confirmed that if the above ratio A... N1 / A M1 And compared to A N2 / A M2 If the scope is as described above, the effect of this disclosure is not impaired.

[0073] <Average thickness of the first unit layer and average thickness of the second unit layer> The average thickness of the first unit layer can be 0.002 μm or more and 0.2 μm or less, and the average thickness of the second unit layer can be 0.002 μm or more and 0.2 μm or less. This further suppresses the propagation of cracks generated on the surface of the coating. The average thickness of the first unit layer can 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 average thickness of the second unit layer can be 0.005 μm or more and 0.15 μm or less, or 0.01 μm or more and 0.10 μm or less.

[0074] The average thickness of the first unit layer and the average thickness of the second unit layer were measured using the same method as the method used to measure the thickness of the first layer.

[0075] like Figure 5 As shown, 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 λ2 μm of the second unit layer 15 to the thickness λ1 μm of the first unit layer 12 can be 1.0 or more and 5.0 or less. The second unit layer, while possessing high oxidation resistance, has low thermal conductivity and is designed to minimize the transfer of heat generated during cutting to the substrate. If the ratio λ2 / λ1 is 1.0 or more, the proportion of the second unit layer in the coating increases relatively, leading to an increase in the Al content in the coating, thereby improving the overall thermal insulation of the cutting tool, especially its wear resistance during continuous cutting. If λ2 / λ1 is 1.0 or more, there is a tendency for the coating to exhibit improved toughness. On the other hand, if λ2 / λ1 is 5.0 or less, there is a tendency to easily obtain a crack propagation suppression effect resulting from the stacking of the first unit layer 12 and the second unit layer 15.

[0076] λ2 / λ1 can be 1.1 or higher and 5.0 or lower, 1.2 or higher and 5.0 or lower, 1.3 or higher and 4.0 or lower, 1.8 or higher and 3.0 or lower, or 2.0 or higher and 2.5 or lower.

[0077] exist Figure 5 For illustrative purposes, the thickness of each of the three first unit layers 12 is denoted as λ1, and the thickness of each of the three second unit layers 15 is denoted as λ2. However, between adjacent first and second unit layers, as long as the above relationship of λ2 / λ1 is satisfied, the thickness λ1 of the three first unit layers 12 does not need to be the same. In addition, the thickness λ2 of the three second unit layers 15 does not need to be the same.

[0078] In the first layer, the number of layers in both the first and second unit layers can be 5 or more and less than 500, 10 or more and less than 500, 100 or more and less than 400, or 200 or more and less than 350. Therefore, by stacking the first and second unit layers, a balanced improvement in hardness and compressive residual stress can be achieved.

[0079] In the first layer, the number of layers of the first unit layer and the second unit layer can be determined by using TEM (transmission electron microscopy) to observe the cross-section of the coated thin film sample at a magnification of 20,000 to 5 million times.

[0080] <Basal layer> like Figure 3 as well as Figure 4 As shown, the coating 3 may further include a base layer 16 disposed between the substrate 2 and the first layer 13. The composition of the base layer 16 may be the same as that of the first unit layer 12 or the second unit layer 15. This improves the adhesion between the substrate 2 and the coating 3.

[0081] When the composition of the base layer is the same as that of the first unit layer, the sliding characteristics of the base layer are good even when the base layer is exposed in the early stage of cutting, thus improving wear resistance.

[0082] When the composition of the base layer is the same as that of the first unit layer, the thickness of the base layer can be greater than that of the first unit layer. This improves the adhesion between the substrate and the coating. The thickness of the base layer can be more than 1.0 times but less than 500 times the thickness of the first unit layer, more than 2.0 times but less than 500 times, more than 4.0 times but less than 120 times, or more than 10.0 times but less than 50 times.

[0083] When the composition of the substrate layer is the same as that of the first unit layer, the thickness of the substrate layer can be 0.1 μm or more and 2 μm or less, 0.3 μm or more and 2 μm or less, or 0.4 μm or more and 2 μm or less. If the thickness of the substrate layer is less than 0.1 μm, it tends to be difficult to achieve the improved wear resistance by setting the substrate layer to the same composition as the first unit layer. If the thickness of the substrate layer exceeds 2 μm, grain enlargement occurs, resulting in grain boundaries, and therefore it tends to be difficult to obtain the improved wear resistance.

[0084] When the composition of the base layer is the same as that of the first unit layer, such as Figure 3 As shown, a first unit layer 12 can also be stacked directly above the base layer 16. Additionally, as... Figure 4 As shown, a second unit layer 15 may also be stacked directly above the base layer 16. When the composition of the base layer 16 is the same as that of the first unit layer 12, and the first unit layer 12 is stacked directly above the base layer 16, the base layer 16 and the first unit layer 12 have a continuous crystal structure.

[0085] When the composition of the base layer is the same as that of the second unit layer, even if the base layer is exposed in the early stage of cutting, oxidation from the interface between the substrate and the coating can be suppressed and cutting heat can be blocked.

[0086] When the composition of the base layer is the same as that of the second unit layer, the thickness of the base layer can also be greater than that of the second unit layer. This further improves the adhesion between the substrate and the coating. The thickness of the base layer can be greater than 1.0 times and less than 500 times the thickness of the second unit layer, more than 2.0 times and less than 500 times, more than 4.0 times and less than 120 times, or more than 10.0 times and less than 50 times.

[0087] When the composition of the base layer is the same as that of the second unit layer, the thickness of the base layer can be greater than 0.1 μm and less than 2 μm, greater than 0.3 μm and less than 2 μm, or greater than 0.4 μm and less than 2 μm.

[0088] When the composition of the base layer is the same as that of the second unit layer, such as Figure 3 As shown, a first unit layer 12 can also be stacked directly above the base layer 16. Additionally, as... Figure 4 As shown, a second unit layer 15 may also be stacked directly above the base layer 16. When the composition of the base layer 16 is the same as that of the second unit layer 15, and the second unit layer 15 is stacked directly above the base layer 16, the base layer 16 and the second unit layer 15 have a continuous crystal structure.

[0089] <Surface Layer> like Figures 1-4 As shown, the coating 3 may also include a surface layer 14 disposed on the side of the first layer 13 opposite to the substrate 2. The surface layer 14 may also be made of TiMoON or AlVON. This reduces the coefficient of friction of the coating and extends the life of the cutting tool.

[0090] Generally, oxynitrides tend to have higher resistance to adhesion relative to the workpiece material compared to nitrides. This improved adhesion resistance is believed to be based on the contribution of oxygen atoms. If the coating includes a surface layer composed of oxynitrides, the tool life is extended by improving the coating's resistance to adhesion relative to the workpiece material.

[0091] In the surface layer, a predetermined color can be imparted by adjusting the ratio of oxygen (O) to nitrogen (N). This allows for the design and recognizability of the cutting tool, making it commercially useful.

[0092] The thickness of the surface layer 14 can be 0.1 μm or more and 2 μm or less. If the thickness of the surface layer 14 is 0.1 μm or more, it is easy to obtain the lubricity imparting effect based on the surface layer 14. If the thickness of the surface layer exceeds 2 μm, there is a tendency that the above-mentioned lubricity imparting effect cannot be further improved. Therefore, considering cost, the thickness of the surface layer can be 2 μm or less.

[0093] <Intermediate Layer> In the cutting tool of Embodiment 1, the coating may include an intermediate layer disposed between the substrate layer and the first layer. Examples of intermediate layers include TiMoN, AlVCeN, AlVN, AlVBN, AlVSiN, AlVYN, and AlVScN. 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.

[0094] [Implementation Method 2: Cutting Tool (2)] use Figures 6-10 Another embodiment of the cutting tool involved in this disclosure will be described.

[0095] Another embodiment of this disclosure (hereinafter also referred to as "Embodiment 2") involves a cutting tool 1 comprising a substrate 2 and a coating 3 disposed on the substrate 2, wherein, The coating 3 includes a second layer 13A. The second layer 13A is composed of alternating layers formed by alternating stacking of the first unit layer 12 and the third unit layer 17. The first unit layer 12 consists of Ti 1-a Moa N constitutes, a is greater than 0.01 and less than 0.20. The third unit layer 17 is composed of Al c V 1-c-d X d N constitutes, X is selected from one or two of the group consisting of boron, silicon, scandium, yttrium, and cerium. c is greater than 0.40 and less than 0.80. d is greater than 0.001 and less than 0.05.

[0096] The cutting tool of Embodiment 2 also has a long tool life, especially in cutting operations performed under conditions of high tool tip temperature. The reason for this is speculated as follows.

[0097] The first unit layer consists of Ti 1-a Mo a N constitutes the structure. Therefore, for the same reasons as described in Embodiment 1, the first layer containing the first unit layer can improve adhesion resistance, slip resistance, and wear resistance during machining where the tool tip becomes hot, such as in dry cutting.

[0098] The third unit layer consists of Al c V 1-c-d X d The second layer is composed of nitrogen (N). The third unit layer contains Al. Al is easily oxidized, therefore the coating containing the third unit layer tends to form a dense oxide layer of Al₂O₃ on the surface side of the second layer. As a result, the thermal barrier properties and oxidation resistance of the second layer can be improved.

[0099] The third unit layer is oxidized during cutting, generating V₂O₅, which is an oxide of V. Since V₂O₅ has a melting point of 690°C, it softens at the temperature during cutting and functions as a lubricant, reducing the coefficient of friction on the tool rake face.

[0100] The second layer consists of alternating layers of first and third unit layers. At the interface between the first and third unit layers, the composition and lattice become discontinuous. Therefore, in the event of cracks forming on the surface of the coating during cutting, crack propagation can be suppressed at the interface. In coatings containing the second layer, chipping and defects are suppressed.

[0101] Except for the composition of the second layer, the base layer, and the surface layer, the cutting tool of Embodiment 2 can be configured to be basically the same as the cutting tool of Embodiment 1. Hereinafter, the "second layer", "base layer" and "surface layer" will be described.

[0102] <Second Layer> In the cutting tool of Embodiment 2, the second layer is composed of alternating layers of first and third unit layers. The alternating layers of first and third unit layers in the second layer can be observed using TEM to examine the cross-section of the coating and confirmed by the difference in contrast. The thickness of the second layer can be set to be the same as the thickness of the first layer described in Embodiment 1. Both the first and third unit layers can be positioned closest to the substrate. The first unit layer can have a cubic crystal structure. The third unit layer can contain a cubic crystal structure.

[0103] <The composition of the first unit layer and the composition of the third unit layer> The composition of the first unit layer Ti in Implementation Method 2 1-a Mo a N can be related to the composition Ti of the first unit layer in Implementation 1. 1-a Mo a N is the same.

[0104] The third unit layer consists of Al c V 1-c-d X d The nitrogen element (N) is selected from one or two elements in the group consisting of boron, silicon, scandium, yttrium, and cerium. The carbon content (c) is 0.40 or higher and 0.80 or lower, and the nitrogen content (d) is 0.001 or higher and 0.05 or lower. The third unit layer 17 possesses both excellent hardness and excellent oxidation resistance. The reasoning is speculated as follows.

[0105] In the third unit layer Al c V 1-c-d X d In N, when X is boron, the hardness of the third unit layer increases due to boron, resulting in a higher overall hardness of the coating. Furthermore, the boron oxide formed by oxidation of the cutting tool surface during cutting densifies the Al oxide in the third unit layer, improving its oxidation resistance. Moreover, since boron oxide has a low melting point, it acts as a lubricant during cutting, suppressing the adhesion of the workpiece material.

[0106] In the third unit layer Al c V 1-c-d X d In N, when X is silicon, the structure of the third unit layer is refined, thereby improving the hardness and oxidation resistance of the third unit layer, and improving the overall hardness and oxidation resistance of the coating.

[0107] In the third unit layer Al c V 1-c-d X dIn N, when X is selected from one or two of the group consisting of scandium (Sc), yttrium (Y), and cerium (Ce), the precipitation of the element at the grain boundary of the third unit layer can suppress the diffusion of their oxides inward through the grain boundary of oxygen from the coating surface. Therefore, the oxidation resistance of the third unit layer is improved, and the life of the cutting tool containing the third unit layer becomes longer.

[0108] The value of c is 0.40 or higher and 0.80 or lower. Therefore, the crystal structure of the third unit layer becomes cubic, resulting in increased hardness and improved wear resistance. c can be 0.45 or higher and 0.75 or lower, 0.50 or higher and 0.70 or lower, or 0.55 or higher and 0.65 or lower.

[0109] The value of d is 0.001 or higher and 0.05 or lower. This improves the hardness and oxidation resistance of the second layer. d can be 0.01 or higher and 0.05 or lower, 0.02 or higher and 0.05 or lower, 0.02 or higher and 0.04 or lower, or 0.02 or higher and 0.03 or lower.

[0110] In this disclosure, "the third unit layer is composed of Al" c V 1-c-d X d "N composition" means that, as long as the effect of this disclosure is not impaired, the third unit layer can be configured in A1. c V 1-c-d X d The N-based structure contains unavoidable impurities. Examples of these unavoidable impurities include, for instance, oxygen and carbon. The overall content of these unavoidable impurities in the third unit layer can be greater than 0 atomic percent and less than 1 atomic percent.

[0111] The content of unavoidable impurities in the above-mentioned c, d, and third unit layer was determined using a transmission electron microscope (TEM). The specific measurement method is the same as the measurement method described in embodiment 1 for a above-mentioned a. Furthermore, it was confirmed that as long as the measurement is performed using the same cutting tool, the measurement results are not biased even if the measurement location is arbitrarily selected.

[0112] In this disclosure, the composition Ti of the first unit layer 1-a Mo a In N, the number of N atoms A N1 The total number of atoms A relative to Ti and Mo M1 The ratio A N1 / A M1 It is above 0.8 and below 1.2. In this disclosure, the composition A1 of the third unit layer... c V 1-c- d X dIn N, the number of N atoms A N3 The total number of atoms A relative to Al, V, and X M3 The ratio A N3 / A M3 It is above 0.8 and below 1.2. Compared to A N3 / A M3 It can be determined using the Rutherford backscattering (RBS) method. It has been confirmed that as long as the above ratio A... N1 / A M1 And compared to A N3 / A M3 If the scope is as described above, the effect of this disclosure is not impaired.

[0113] <Average thickness of the first unit layer and average thickness of the third unit layer> The average thickness of the first unit layer can be 0.002 μm or more and 0.2 μm or less, and the average thickness of the third unit layer can be 0.002 μm or more and 0.2 μm or less. This further suppresses the propagation of cracks generated on the surface of the coating. The average thickness of the first unit layer can 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 average thickness of the third unit layer can be 0.005 μm or more and 0.15 μm or less, or 0.01 μm or more and 0.10 μm or less.

[0114] The average thickness of the first unit layer and the average thickness of the third unit layer can be determined by the same method as the method for measuring the thickness of the first layer described in Embodiment 1.

[0115] like Figure 10 As shown, 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 μm of the third unit layer 17 to the thickness λ1 μm of the first unit layer 12 can be 1.0 or more and 5.0 or less. The third unit layer, while possessing high oxidation resistance, also exhibits low thermal conductivity, making it difficult to transfer heat generated during cutting to the substrate. If the ratio λ3 / λ1 is 1.0 or more, the proportion of the third unit layer in the coating increases relatively, the Al content in the coating increases, thereby improving the overall thermal insulation of the cutting tool, especially the wear resistance during continuous cutting. If λ3 / λ1 is 1.0 or more, there is a tendency for the coating to have improved toughness. On the other hand, if λ3 / λ1 is 5.0 or less, there is a tendency to easily obtain a crack propagation suppression effect resulting from the stacking of the first unit layer and the third unit layer.

[0116] λ3 / λ1 can be 1.1 or higher and 5.0 or lower, 1.2 or higher and 5.0 or lower, 1.3 or higher and 4.0 or lower, 1.8 or higher and 3.0 or lower, or 2.0 or higher and 2.5 or lower.

[0117] exist Figure 10 For illustrative purposes, the thickness of each of the three first unit layers 12 is denoted as λ1, and the thickness of each of the three third unit layers 17 is denoted as λ3. However, between adjacent first and third unit layers, as long as the above relationship of λ3 / λ1 is satisfied, the thickness λ1 of the three first unit layers 12 does not need to be the same. In addition, the thickness λ3 of the three third unit layers 17 does not need to be the same.

[0118] In the second layer, the number of stacked units for the first and third unit layers can be 4 or more but less than 800, 10 or more but less than 500, 100 or more but less than 400, or 200 or more but less than 350. Therefore, by stacking the first and third unit layers, a balanced increase in both hardness and compressive residual stress can be achieved.

[0119] In the second layer, the stacking number of the first unit layer and the third unit layer can be determined by the same method as the method for determining the stacking number of the first unit layer and the second unit layer described in Embodiment 1.

[0120] <Basal layer> like Figure 8 as well as Figure 9 As shown, the coating 3 further includes a base layer 16 disposed between the substrate 2 and the second layer 13A. The composition of the base layer 16 may be the same as that of the first unit layer 12 or the third unit layer 17. This improves the adhesion between the substrate 2 and the coating 3.

[0121] The effect and thickness of the base layer when the composition of the base layer is the same as that of the first unit layer are as described in Embodiment 1.

[0122] When the composition of the base layer 16 is the same as that of the third unit layer 17, the third unit layer tends to have low stress, thus improving the peel resistance of the coating, especially in intermittent machining such as milling and end milling where the load is repeatedly applied to the tool tip.

[0123] When the composition of the base layer is the same as that of the third unit layer, the thickness of the base layer can be greater than that of the third unit layer. This improves the adhesion between the substrate and the coating. The thickness of the base layer can be greater than 1.0 times and less than 500 times the thickness of the third unit layer, greater than 2.0 times and less than 500 times, greater than 4.0 times and less than 120 times, or greater than 10.0 times and less than 50 times.

[0124] When the composition of the substrate layer is the same as that of the third unit layer, the thickness of the substrate layer can be greater than 0.1 μm and less than 2 μm, greater than 0.3 μm and less than 2 μm, or greater than 0.4 μm and less than 2 μm.

[0125] When the composition of the basal layer is the same as that of the third unit layer, such as Figure 8 As shown, a first unit layer can also be stacked directly above the base layer. Additionally, as... Figure 9 As shown, a third unit layer can also be stacked directly above the base layer. When the composition of the base layer and the third unit layer are the same, and a third unit layer is stacked directly above the base layer, the base layer and the third unit layer have a continuous crystal structure.

[0126] <Surface Layer> like Figures 6-9 As shown, the coating 3 may further include a surface layer 14 disposed on the side of the second layer 13A opposite to the substrate 2. The surface layer 14 may be made of TiMoON or AlVXON. Here, X may be one or two selected from the group consisting of boron, silicon, scandium, yttrium, and cerium. X may also be the same element as X used in the third unit layer. As a result, the coefficient of friction of the coating can be reduced, thereby extending the life of the cutting tool.

[0127] By adjusting the ratio of oxygen (O) to nitrogen (N) in the surface layer, a predetermined color can be imparted. This allows for the design and recognizability of cutting tools, making them commercially useful.

[0128] The thickness of the surface layer 14 can be as described in Embodiment 1.

[0129] [Implementation Method 3: Method for Manufacturing a Cutting Tool] In Embodiment 3, a method for manufacturing the cutting tool according to Embodiment 1 or Embodiment 2 will be described. The method for manufacturing the cutting tool in Embodiment 3 includes a first step of preparing a substrate and a second step of forming a coating on the substrate. The second step includes a step of forming a first layer or a second layer. The details of each step will be described below.

[0130] <First Process> In the first step, a substrate is prepared. The substrate can be the one described in Embodiment 1. Any substrate can be prepared as long as it is a conventionally known substrate.

[0131] <Second Process> In the second process, a coating is formed on the substrate. The second process includes the process of forming a first layer or a second layer.

[0132] In the process of forming the first layer, physical vapor deposition (PVD) is used to form the first layer by alternately stacking first and second unit layers. In the process of forming the second layer, PVD is used to form the second layer by alternately stacking first and third unit layers. To improve the wear resistance of the coating containing the first or second layer, it is effective to form a layer composed of a highly crystalline compound. The inventors of this invention have discovered that by using physical vapor deposition as the method for forming the first and second layers, it is possible to form a layer composed of a highly crystalline compound, resulting in a coating with excellent wear resistance.

[0133] As a PVD method, at least one selected from the group consisting of cathodic arc ion plating, balanced magnetron sputtering, unbalanced magnetron sputtering, and HiPIMS (High Power Impulse Magnetron Sputtering) can be used. Cathodic arc ion plating, which uses elements with high ionization rates, can be used. When using cathodic arc ion plating, the surface of the substrate can be subjected to metal ion bombardment treatment before forming the first or second layer, thus significantly improving the adhesion between the substrate and the coating containing the first or second layer.

[0134] Cathodic arc ion plating can be performed as follows: a substrate is placed in the apparatus, and a target is placed as the cathode. A high voltage is applied to the target to generate an arc discharge, thereby ionizing and evaporating the atoms constituting the target, and causing the material to accumulate on the substrate.

[0135] Balanced magnetron sputtering can be performed as follows: a substrate is placed in a device, and a target is placed on a magnetron electrode equipped with a magnet that forms a balanced magnetic field. High-frequency power is applied between the magnetron electrode and the substrate to generate a gas plasma. The gas ions generated by the generation of the gas plasma collide with the target, causing atoms released from the target to accumulate on the substrate.

[0136] Unbalanced magnetron sputtering can be performed, for example, by making the magnetic field generated by the magnetron electrodes in the balanced magnetron sputtering method described above unbalanced. Furthermore, the HiPIMS method, which can apply high voltage to obtain dense films, can also be used.

[0137] <Other Processes> The second process, in addition to the process of forming the first or second layer, may also include surface treatment processes such as brush grinding, dry or wet shot peening, etc., to coat the film. Furthermore, the second process may include processes for forming other layers such as a base layer, a surface layer, and an intermediate layer. These other layers can be formed using conventional chemical vapor deposition (CVD) or physical vapor deposition (PVD). From the viewpoint that other layers can be continuously formed alongside the first, second, or third unit layer within a single PVD apparatus, the other layers are preferably formed using PVD.

[0138] Example The present embodiment will be further described in detail through examples. However, the present embodiment is not limited to these examples.

[0139] [Example 1] <Sample 1~Sample 19, Sample 101~Sample 105> Manufacturing of cutting tools

[0140] Figure 11 This is a schematic cross-sectional view of the cathode arc ion plating apparatus used in Example 1. Figure 12 yes Figure 11 A top view of the device.

[0141] exist Figure 11 as well as Figure 12 In the apparatus, an alloy target, which serves as the coating metal material, is installed within chamber 101. This includes a cathode 106 for the first unit layer, a cathode 107 for the second unit layer, and a cathode 120 for the surface layer. A rotating substrate holder 104 is also installed for setting the substrate. The composition of cathode 106 is adjusted to achieve the composition of the first unit layer (Table 1). The composition of cathode 107 is adjusted to achieve the composition of the second unit layer (Table 1). The composition of cathode 120 is adjusted to achieve the composition of the surface layer (Table 2).

[0142] An arc power supply 108 is installed on cathode 106, an arc power supply 109 is installed on cathode 107, and an arc power supply (not shown) is installed on cathode 120. Additionally, a bias power supply 110 is installed on substrate holder 104. Furthermore, a gas inlet 105 for introducing gas 102 is provided inside chamber 101, and a gas outlet 103 is provided to regulate the pressure inside chamber 101, forming a structure that allows a vacuum pump to draw gas 102 from chamber 101 through gas outlet 103.

[0143] The substrate holder 104 is equipped with a cutting tool of JIS standard CNMG120408 and JIS standard CNMG120408, and a cutting tool of SEMT13T3AGSN manufactured by Sumitomo Electric Industries, Ltd., which are both made of cemented carbide of JIS standard K20 grade and have a shape of SEMT13T3AGSN.

[0144] Next, a vacuum pump is used to depressurize the pressure inside chamber 101. While rotating the substrate, a heater installed in the device is used to heat the temperature to 600°C. Vacuuming is then performed until the pressure inside chamber 101 reaches 1.0 × 10⁻⁶. -4 Next, argon gas is introduced through the gas inlet to maintain the pressure inside chamber 101 at 2.0 Pa. The voltage of the bias power supply 110 is gradually increased to -1000V, and the surface of the substrate is cleaned for 15 minutes. Afterward, the substrate is cleaned by purging argon gas from chamber 101 (argon bombardment treatment). Through the above, the substrate for the cutting tools of each sample is prepared.

[0145] Next, while the substrate is rotated in the center, nitrogen gas is introduced as a reaction gas, and the substrate temperature is maintained at 600°C, the reaction gas pressure is 3.3 Pa, and the voltage of the bias power supply 110 is within a predetermined constant range of -50V to -200V. An arc current of 150A is supplied to the cathodes 106 and 107 respectively, thereby generating metal ions from the cathodes 106 and 107, forming a base layer with the composition shown in Table 2 and a first layer with the composition shown in Table 1 on the substrate.

[0146] When a substrate layer is formed, the first layer is formed by alternately stacking the first unit layer and the second unit layer on the substrate layer, as shown in Table 1, with the same number of stacks. When no substrate layer is formed, the first layer is formed by alternately stacking the first unit layer and the second unit layer on the substrate layer, as shown in Table 1, with the same number of stacks. Furthermore, the thickness of the substrate layer, the thickness of each of the first and second unit layers in the first layer, and the number of stacks are adjusted by rotating the substrate. Then, when the thickness of the substrate layer and the first layer reach the thicknesses shown in Tables 1 and 2, respectively, the current supplied to the evaporation source is stopped. A "-" in the "Substrate Layer" column of Table 2 indicates that no substrate layer exists.

[0147] Next, while introducing nitrogen and oxygen as reactant gases into chamber 101, and maintaining the substrate temperature at 500°C, the reactant gas pressure at 2.0 Pa, and the bias power supply 110 voltage at -350 V, an arc current of 120 A was supplied to cathode 120, thereby generating metal ions from cathode 120 and forming a surface layer on the first layer. When the thickness of the surface layer reached the thickness shown in Table 2, the current supplied to the evaporation source was stopped. The amounts of nitrogen and oxygen introduced were adjusted to obtain the surface layer composition shown in Table 2. Using the above methods, cutting tools for each sample were fabricated. A "-" in the "Surface Layer" column of Table 2 indicates that a surface layer is not present.

[0148] [Table 1]

[0149] [Table 2]

[0150] evaluate

[0151] <Determination of the composition of the first unit layer> For each sample's cutting tool, the composition of the first unit layer was determined using the method described in Embodiment 1 to obtain Ti. 1-a Mo a The value of 'a' in N is recorded in column "a" of Table 1. In Table 1, if "-" is recorded in column "a", it indicates that the first unit layer does not exist.

[0152] <Determination of the composition of the second unit layer> For each sample's cutting tool, the composition of the second unit layer was determined using the method described in Embodiment 1 to obtain Al. b V 1-b The value of b in N. Record the result in column "b" of Table 1.

[0153] <Determination of the composition of the basal layer and the surface layer> For each sample's cutting tool, the composition of the base layer and surface layer was determined using the method described in Embodiment 1. The results were recorded in the "Composition" column of "Base Layer" and the "Composition" column of "Surface Layer" in Table 2. A "-" in the "Composition" column of "Base Layer" in Table 2 indicates that no base layer exists, and a "-" in the "Composition" column of "Surface Layer" indicates that no surface layer exists.

[0154] <Determination of the number of layers> For each sample's cutting tool, the number of layers for the first unit layer and the second unit layer is determined using the method described in Embodiment 1. For example, a layer count of 10 indicates that the alternating layers consist of 10 first unit layers and 10 second unit layers. The results are recorded in the "Number of Layers" column of Table 1.

[0155] <Determination 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 base layer, and the thickness of the surface layer> For each sample's 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 base layer, and the thickness of the surface layer were determined using the method described in Embodiment 1. The results were recorded in the "Average Thickness [μm]" column for "First Unit Layer," the "Average Thickness [μm]" column for "Second Unit Layer," the "Thickness [μm]" column for "First Layer," and the "Thickness [μm]" column for "Base Layer" and "Surface Layer" column in Table 2. A "-" indicates that no corresponding layer exists.

[0156] <Determination of λ2 / λ1> For each sample's cutting tool, λ2 / λ1 was calculated using the method described in Embodiment 1. The results were recorded in the "λ2 / λ1" column of Table 1. Furthermore, if the "λ2 / λ1" column of Table 1 is marked with "-", it indicates that at least one of the first unit layer and the second unit layer does not exist.

[0157] <Determination of the crystal structure of the first unit layer> In samples 1 to 19, the crystal structures of the first and second unit layers were confirmed by XRD analysis of the cutting tools used for each sample. The specific method is as described in Embodiment 1. It was confirmed that in samples 1 to 19, both the first and second unit layers have a cubic crystal structure.

[0158] <Determination of the hardness of the coating> In samples 1 to 19, the hardness of the coating was measured using the method described in Embodiment 1. It was confirmed that the hardness of the coating in these samples was in the range of 30 GPa or more and 55 GPa or less.

[0159] <Determination of compressive residual stress in coated films> In samples 1 to 19, the compressive residual stress of the coating was measured using the method described in Embodiment 1. It was confirmed that the absolute value of the compressive residual stress of the coating in these samples was 6 GPa or less.

[0160] <Cutting Test 1: Continuous Turning Test> For each CNMG120408 shaped cutting tool, continuous turning tests were performed under the following cutting conditions, and the time until the wear on the flank face of the tool tip reached 0.2 mm was measured. The results are recorded in the "Cutting Time [minutes]" column of "Cutting Test 1" in Table 2. A longer cutting time indicates a longer tool life.

[0161] Cutting conditions

[0162] Material being cut: Inconel 718 (HB400) alloy Cutting speed: 90m / min Feed rate: 0.2 mm / rev Incision: 1.5mm Coolant: Water-soluble The cutting process performed under the above cutting conditions is equivalent to the cutting process performed under conditions of high tool tip temperature.

[0163] The cutting tools of specimens 1 to 19 correspond to the examples, and the cutting tools of specimens 101 to 105 correspond to the comparative examples. It was confirmed that the cutting tools of specimens 1 to 19 have a longer tool life in cutting operations performed under high tool tip temperature conditions compared to the cutting tools of specimens 101 to 105.

[0164] <Cutting Test 2: Milling Test> For each sample with a SEMT13T3AGSN shaped cutting tool, the centerline of a 150mm wide plate was aligned with the center of a 160mm wide cutter. Surface milling was performed under the following cutting conditions, and the cutting length was measured until the flank wear of the tool tip reached 0.2mm. The results are recorded in the "Cutting Length [km]" column of "Cutting Test 2" in Table 2. A longer cutting length indicates a longer tool life.

[0165] Cutting conditions

[0166] Material to be cut: SKD11 (HB=235) Cutting speed: 200m / min Feed rate: 0.15 mm / tool Axial cut ap: 1.5mm Radial cut ae: 150mm Coolant: Dry The cutting process performed under the above cutting conditions is equivalent to the cutting process performed under conditions of high tool tip temperature.

[0167] The cutting tools of specimens 1 to 19 correspond to the examples, and the cutting tools of specimens 101 to 105 correspond to the comparative examples. It was confirmed that the cutting tools of specimens 1 to 19 have a longer tool life in cutting operations performed under high tool tip temperature conditions compared to the cutting tools of specimens 101 to 105.

[0168] [Example 2] <Samples 51~85, Samples 151~176> Manufacturing of cutting tools

[0169] The substrates for the cutting tools of each sample were prepared using the same method as in Example 1. While the substrate was rotated in the center, argon and nitrogen were introduced as reactant gases. At a predetermined constant value, maintaining the substrate temperature at 600°C, the reactant gas pressure at 2.0 Pa, and the voltage of the bias power supply 110 within the range of -50V to -200V, an arc current of 100A was supplied to cathodes 106 and 107 respectively. This generated metal ions from cathodes 106 and 107, forming a base layer and a second layer with the compositions shown in Tables 3 to 6 on the substrate. The composition of cathode 106 was adjusted to obtain the composition of the first unit layer shown in Tables 3 to 4. Furthermore, the composition of cathode 107 was adjusted to obtain the composition of the third unit layer shown in Tables 3 to 4. The composition of cathode 120 was adjusted to obtain the composition of the surface layer shown in Tables 5 to 6.

[0170] When a base layer is formed, the second layer is formed by alternately stacking the first unit layer and the third unit layer on the base layer, as shown in Tables 3 and 4. When a base layer is not formed, the second layer is formed by alternately stacking the first unit layer and the third unit layer on the substrate, as shown in Tables 3 and 4. Furthermore, the thickness of the base layer, the thickness of each of the first and third unit layers in the second layer, and the number of stacks are adjusted by rotating the substrate. Then, when the thickness of the base layer and the second layer reaches the thicknesses shown in Tables 3 to 6, the current supplied to the evaporation source is stopped. A "-" in the "Base Layer" column of Tables 5 and 6 indicates that a base layer is not present.

[0171] Next, while introducing nitrogen and oxygen as reactant gases into chamber 101, and maintaining the substrate temperature at 350°C, the reactant gas pressure at 2.0 Pa, and the bias power supply 110 voltage at -350 V, an arc current of 100 A was supplied to cathode 120, thereby generating metal ions from cathode 120 and forming a surface layer on the second layer. The current supplied to the evaporation source was stopped when the surface layer thickness reached the thickness shown in Tables 5 and 6. The amounts of nitrogen and oxygen introduced were adjusted to obtain the surface layer composition shown in Tables 5 and 6. Using the above methods, cutting tools for each sample were fabricated. A "-" in the "Surface Layer" column of Tables 5 and 6 indicates that a surface layer is not present.

[0172] [Table 3]

[0173] [Table 4]

[0174] [Table 5]

[0175] [Table 6]

[0176] evaluate

[0177] For each sample and the cutting tool involved, the composition of the first unit layer, the third unit layer, the substrate layer, the surface layer, the number of layers in each of the first and third unit layers, the average thickness of the first unit layer, the average thickness of the third unit layer, the thickness of the second layer, the thickness of the substrate layer, the thickness of the surface layer, λ3 / λ1, the crystal structure of the first unit layer, the hardness of the coating, and the compressive residual stress of the coating were measured. The measurement methods for each item are as described in Example 1. The results are shown in Tables 3 to 6.

[0178] In samples 51 to 85, it was confirmed that both the first unit layer and the second unit layer have a cubic crystal structure. It was also confirmed that the hardness of the coatings in samples 51 to 85 is between 30 GPa and 55 GPa. Furthermore, it was confirmed that the absolute value of the compressive residual stress in the coatings of samples 51 to 85 is 6 GPa or less.

[0179] <Cutting Test 3: Continuous Turning Test> For each CNMG120408 shaped cutting tool, continuous turning tests were performed under the following cutting conditions, and the time until the wear on the flank face of the tool tip reached 0.2 mm was measured. The results are recorded in the "Cutting Time [minutes]" column of "Cutting Test 3" in Tables 5 and 6. Furthermore, in Tables 5 and 6, a longer cutting time indicates a longer tool life.

[0180] (Cutting conditions) Material to be cut: SCM440 (HB320) Cutting speed: 360 m / min Feed rate: 0.35 mm / rev Incision: 2.0mm Coolant: Water-soluble The cutting process performed under the above cutting conditions is equivalent to the cutting process performed under conditions of high tool tip temperature.

[0181] The cutting tools of specimens 51 to 85 correspond to the examples, and the cutting tools of specimens 151 to 176 correspond to the comparative examples. It was confirmed that the cutting tools of specimens 51 to 85 have a longer tool life in cutting operations performed under high tool tip temperature conditions compared to the cutting tools of specimens 151 to 176.

[0182] <Cutting Test 4: Milling Test> For each sample using a cutting tool of the SEMT13T3AGSN shape, the centerline of a 150mm wide plate was aligned with the center of a 160mm wide cutter. Surface milling was performed under the following cutting conditions, and the cutting length was measured until the flank wear of the tool tip reached 0.2mm. The results are recorded in the "Cutting Length [km]" column of "Cutting Test 4" in Tables 5 and 6. Furthermore, in Tables 5 and 6, a longer cutting length indicates a longer tool life.

[0183] Cutting conditions

[0184] Material to be cut: FCD700 (HB=250) Cutting speed: 220 m / min Feed rate: 0.2 mm / tool Axial cut ap: 2.0mm Radial cut ae: 150mm Coolant: Dry The cutting process performed under the above cutting conditions is equivalent to the cutting process performed under conditions of high tool tip temperature.

[0185] The cutting tools of specimens 51 to 85 correspond to the examples, and the cutting tools of specimens 151 to 176 correspond to the comparative examples. It was confirmed that the cutting tools of specimens 51 to 85 have a longer tool life in cutting operations performed under high tool tip temperature conditions compared to the cutting tools of specimens 151 to 176.

[0186] The embodiments and examples of this disclosure have been described above, but it is also intended from the outset that the above-described embodiments and examples may be appropriately combined or modified.

[0187] The embodiments and examples disclosed herein should be considered exemplary in all respects, and not restrictive. The scope of the invention is defined not by the foregoing embodiments and examples, but by the claims, and is intended to include all modifications equivalent to and within the scope of the claims.

[0188] Explanation of reference numerals in the attached figures: 1: Cutting tool; 2: Substrate; 3: Coating; 12: First unit layer; 13: First layer; 13A: Second layer; 14: Surface layer; 15: Second unit layer; 16: Base layer; 17: Third unit layer; 101: Chamber; 102: Gas; 103: Gas outlet; 104: Substrate holder; 105: Gas inlet; 106, 107, 120: Cathode; 108, 109: Arc power supply; 110: Bias power supply.

Claims

1. A cutting tool comprising a substrate and a coating disposed on the substrate, wherein, The coating comprises a first layer. The first layer is composed of alternating layers of first unit layers and second unit layers. The first unit layer consists of Ti 1-a Mo a N constitutes, The value of a is greater than 0.01 and less than 0.

20. The second unit layer consists of Al b V 1-b N constitutes, The value of b is greater than 0.40 and 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, the ratio of the thickness λ2μm of the second unit layer to the thickness λ1μm of the first unit layer, λ2 / λ1, is 1.0 or more and 5.0 or less.

3. The cutting tool according to claim 1 or 2, wherein, The average thickness of the first unit layer is greater than 0.002 μm and less than 0.2 μm. The average thickness of the second unit layer is greater than 0.002 μm and less than 0.2 μm.

4. The cutting tool according to any one of claims 1 to 3, wherein, The coating further includes a surface layer disposed on the side of the first layer opposite to the substrate. The surface layer is composed of TiMoON or AlVON.

5. A cutting tool comprising a substrate and a coating disposed on the substrate, wherein, The coating comprises a second layer. The second layer consists of alternating layers formed by alternating stacks of the first unit layer and the third unit layer. The first unit layer consists of Ti 1-a Mo a N constitutes, The value of a is greater than 0.01 and less than 0.

20. The third unit layer is composed of Al c V 1-c-d X d N constitutes, X is selected from one or two of the group consisting of boron, silicon, scandium, yttrium, and cerium. The value of c is greater than 0.40 and less than 0.

80. The value of d is greater than or equal to 0.001 and less than or equal to 0.

05.

6. The cutting tool according to claim 5, wherein, In the first unit layer and the third unit layer adjacent to the first unit layer, the ratio of the thickness λ3μm of the third unit layer to the thickness λ1μm of the first unit layer, λ3 / λ1, is 1.0 or more and 5.0 or less.

7. The cutting tool according to claim 5 or 6, wherein, The average thickness of the first unit layer is greater than 0.002 μm and less than 0.2 μm. The average thickness of the third unit layer is greater than 0.002 μm and less than 0.2 μm.

8. The cutting tool according to any one of claims 5 to 7, wherein, The coating further includes a surface layer disposed on the side of the second layer opposite to the substrate. The surface layer is composed of TiMoON or AlVXON. X is selected from one or two of the group consisting of boron, silicon, scandium, yttrium, and cerium.

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