Cutting tool

Abstract

A cutting tool comprising a substrate and a coating disposed on the substrate, wherein the coating includes a first layer composed of alternating layers of first unit layers and second unit layers, the first unit layer being made of Al a Cr 1‑a‑b Ce b N is composed of a, where a is 0.400 or higher and 0.800 or lower, and b is 0.001 or higher and 0.100 or lower. The second unit layer is composed of Al. c Ti 1‑c N is composed of c being greater than 0.30 and less than 0.75, and a and c satisfy the relationship a > c.

Description

Technical Field

[0001] This disclosure relates to cutting tools. Background Technology

[0002] Cutting tools having a substrate and a coating disposed on the substrate have been used for cutting processes (Patent Document 1 and Patent Document 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-64845

[0006] Patent Document 2: Japanese Patent Application Publication No. 9-300105 Summary of the Invention

[0007] One aspect of this disclosure relates to a cutting tool having a substrate and a coating disposed on the substrate, wherein,

[0008] The coating comprises a first layer.

[0009] The first layer is composed of alternating layers of first unit layers and second unit layers.

[0010] The first unit layer consists of Al a Cr 1-a-b Ce b N constitutes,

[0011] The value of a is greater than 0.400 and less than 0.800.

[0012] The value of b is greater than 0.001 and less than 0.100.

[0013] The second unit layer consists of Al c Ti 1-c N constitutes,

[0014] The value of c is greater than 0.30 and less than 0.75.

[0015] The relationship between a and c is a > c. Attached Figure Description

[0016] Figure 1 This is a schematic enlarged cross-sectional view of an example of a cutting tool according to the first embodiment.

[0017] Figure 2 This is a schematic enlarged cross-sectional view of an example of a cutting tool according to the first embodiment.

[0018] Figure 3This is a schematic enlarged cross-sectional view of an example of a cutting tool according to the first embodiment.

[0019] Figure 4 This is a schematic enlarged cross-sectional view of an example of a cutting tool according to the first embodiment.

[0020] Figure 5 This is a diagram used to illustrate an example of the thickness ratio of the first unit layer to the second unit layer.

[0021] Figure 6 This is a schematic enlarged cross-sectional view of an example of a cutting tool according to the second embodiment.

[0022] Figure 7 This is a schematic enlarged cross-sectional view of an example of a cutting tool according to the second embodiment.

[0023] Figure 8 This is a schematic enlarged cross-sectional view of an example of a cutting tool according to the second embodiment.

[0024] Figure 9 This is a schematic enlarged cross-sectional view of an example of a cutting tool according to the second embodiment.

[0025] Figure 10 This is a diagram used to illustrate an example of the thickness ratio of the first unit layer to the third unit layer.

[0026] Figure 11 This is a schematic cross-sectional view of the cathode arc ion plating apparatus used in the embodiment.

[0027] Figure 12 yes Figure 11 A schematic top view of the cathode arc ion plating apparatus shown. Detailed Implementation

[0028] [The problem this disclosure aims to solve]

[0029] Machining plays a central role even in manufacturing technology, constantly demanding technological evolution and further advancements. Machining technology fundamentally requires high speed, high efficiency, and high precision. A recent trend is the increasing difficulty in machining materials, necessitating solutions to this challenge. Building on this, in the machining field, there is growing focus on the SDGs (Sustainable Development Goals) in order to achieve a more sustainable and better world by 2030. Sustainable development refers to building a society resilient to natural threats without compromising the resources needed by future generations. Improving machining technology can be expected to reduce environmental impact, such as energy savings in manufacturing processes and reduced waste generated during machining. In cutting tools, the development of coated tool materials with high high-temperature hardness and a combination of hardness and toughness aims to extend tool life.

[0030] Conventionally, as a type of coating tool material, nitride and carbonitride films, mainly composed of Ti and Al, are applied to the surface of a substrate (Patent Document 1 and Patent Document 2). However, from the perspective of SDGs and environmental protection, due to the requirements for dry machining without cutting fluids, the need for higher cutting speeds to improve machining efficiency, and the diversification of materials being cut, especially in the aerospace and medical fields where the cutting of heat-resistant alloys and titanium alloys, which are considered difficult-to-cut materials, there is a trend towards higher tool tip temperatures during cutting. If the tool tip temperature becomes high, the tool life becomes extremely short. Therefore, there is a demand for cutting tools that can exhibit excellent tool life even under such harsh cutting conditions.

[0031] [The Effects of This Disclosure]

[0032] 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.

[0033] [Description of embodiments of this disclosure]

[0034] First, embodiments of this disclosure will be described.

[0035] (1) One aspect of this disclosure relates to a cutting tool having a substrate and a coating disposed on the substrate, wherein the coating comprises a first layer, the first layer being composed of alternating layers of alternating first unit layers and second unit layers, the first unit layer being composed of Al a Cr 1-a-b Ce bN is composed of a, where a is 0.400 or higher and 0.800 or lower, and b is 0.001 or higher and 0.100 or lower. The second unit layer is composed of Al. c Ti 1-c N is composed of c being greater than 0.30 and less than 0.75, and a and c satisfy the relationship a > c.

[0036] 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.

[0037] (2) Alternatively, based on (1) above, in the first unit layer and the second unit layer adjacent to the first unit layer, the ratio λ1 / λ2 of the thickness λ1 of the first unit layer to the thickness λ2 of the second unit layer is 1.0 or more and 5.0 or less. Therefore, the cutting tool can have a longer tool life.

[0038] (3) Alternatively, based on (1) or (2) above, the average thickness of the first unit layer is 0.002 μm or more and 0.2 μm or less.

[0039] The average thickness of the second unit layer is greater than 0.002 μm and less than 0.2 μm.

[0040] As a result, cutting tools can have a longer tool life.

[0041] (4) Alternatively, based on any of (1) to (3) above, the coating may further include a second layer disposed between the substrate and the first layer.

[0042] The composition of the second layer is the same as that of the first unit layer or the second unit layer.

[0043] As a result, cutting tools can have a longer tool life.

[0044] (5) Alternatively, based on (4) above, the composition of the second layer is the same as that of the first unit layer.

[0045] The second layer is thicker than the first unit layer.

[0046] As a result, cutting tools can have a longer tool life.

[0047] (6) Alternatively, based on (4) above, the composition of the second layer is the same as the composition of the second unit layer.

[0048] The thickness of the second layer is greater than the thickness of the second unit layer.

[0049] As a result, cutting tools can have a longer tool life.

[0050] (7) Alternatively, based on (1) to (6) above, the coating may further include a third layer disposed on the side of the first layer opposite to the substrate.

[0051] The third layer is composed of AlCrCeCN.

[0052] As a result, cutting tools can have a longer tool life.

[0053] (8) Another aspect of this disclosure relates to a cutting tool having a substrate and a coating disposed on the substrate, wherein,

[0054] The coating comprises a first A layer.

[0055] The first A layer is composed of alternating layers of first unit layers and third unit layers.

[0056] The first unit layer consists of Al a Cr 1-a-b Ce b N constitutes,

[0057] The value of a is greater than 0.400 and less than 0.800.

[0058] The value of b is greater than 0.001 and less than 0.100.

[0059] The third unit layer is composed of Al d Ti 1-d-e M e N constitutes,

[0060] M is silicon or boron.

[0061] The value of d is greater than 0.30 and less than 0.75.

[0062] The value of e is greater than 0 and less than 0.05.

[0063] The relationship between a and d is a > d.

[0064] 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.

[0065] (9) Alternatively, based on (8) above, in the first unit layer and the third unit layer adjacent to the first unit layer, the ratio of the thickness λ1 of the first unit layer to the thickness λ3 of the third unit layer, λ1 / λ3, is 1.0 or more and 5.0 or less.

[0066] As a result, cutting tools can have a longer tool life.

[0067] (10) Alternatively, based on (8) or (9) above, M may be silicon.

[0068] As a result, cutting tools can have a longer tool life.

[0069] (11) Alternatively, based on (8) or (9) above, M may be boron.

[0070] As a result, cutting tools can have a longer tool life.

[0071] (12) Alternatively, based on 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.

[0072] The average thickness of the third unit layer is greater than 0.002 μm and less than 0.2 μm.

[0073] As a result, cutting tools can have a longer tool life.

[0074] (13) Alternatively, based on any of (8) to (12) above, the coating may further comprise a second layer disposed between the substrate and the first A layer.

[0075] The composition of the second layer is the same as that of the first unit layer or the third unit layer.

[0076] As a result, cutting tools can have a longer tool life.

[0077] (14) Alternatively, based on (13) above, the composition of the second layer is the same as that of the first unit layer.

[0078] The second layer is thicker than the first unit layer.

[0079] As a result, cutting tools can have a longer tool life.

[0080] (15) Alternatively, based on (13) above, the composition of the second layer is the same as that of the third unit layer.

[0081] The second layer is thicker than the third unit layer.

[0082] As a result, cutting tools can have a longer tool life.

[0083] (16) Alternatively, based on any of (8) to (15) above, the coating may further comprise a third layer disposed on the side of the first A layer opposite to the substrate.

[0084] The third layer is composed of AlCrCeCN.

[0085] As a result, cutting tools can have a longer tool life.

[0086] [Details of the embodiments disclosed herein]

[0087] Hereinafter, specific examples of the cutting tools of this disclosure will be described 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.

[0088] In this disclosure, expressions such as "A~B" refer to the upper and lower limits of a range (i.e., above A and below B). When there is no unit recorded in A but only in B, the unit of A is the same as the unit of B.

[0089] In this disclosure, when compounds are represented by chemical formulas, the atomic ratios are not specifically limited to those within the stoichiometric range, and all conventionally known atomic ratios are included. For example, when referred to as "AlCrCeN", the ratio of the number of atoms constituting AlCrCeN includes all conventionally known atomic ratios.

[0090] In this disclosure, when more than one value is recorded as the lower limit and the upper limit of the numerical range, combinations of any value recorded in the lower limit and any value recorded in the upper limit are also disclosed. For example, when a1, b1, and c1 are recorded as the lower limit and a2, b2, and c2 are recorded as the upper limit, the following combinations are disclosed: a1 and below a2, a1 and below b2, a1 and below c2, b1 and below a2, b1 and below b2, b1 and below c2, c1 and below a2, c1 and below b2, and c1 and below c2.

[0091] [First Implementation Method: Cutting Tool (1)]

[0092] use Figures 1-5 A cutting tool according to one embodiment of this disclosure will be described.

[0093] One embodiment of this disclosure (hereinafter also referred to as the "first embodiment") involves a cutting tool 1 comprising a substrate 2 and a coating 3 disposed on the substrate 2, wherein,

[0094] The coating 3 comprises a first layer 13.

[0095] The first layer 13 is composed of alternating layers of first unit layer 12 and second unit layer 15.

[0096] The first unit layer 12 is composed of Al a Cr 1-a-b Ce b N constitutes,

[0097] The value of 'a' is above 0.400 and below 0.800.

[0098] The value of b is greater than 0.001 and less than 0.100.

[0099] The second unit layer 15 is composed of Al c Ti 1-c N constitutes,

[0100] The value of c is above 0.30 and below 0.75.

[0101] The condition 'a' and the condition 'c' satisfy the relationship 'a > c'.

[0102] The cutting tool 1 of the first embodiment 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.

[0103] (a1) The first unit layer 12 is composed of nitrides containing Al, Cr, and Ce. Al is easily oxidized, thus a dense oxide layer composed of Al2O3 is easily formed on the surface side of the coating 3 of the first unit layer 12. Furthermore, the standard formation energy of Ce oxide is lower than that of Al, so it is more easily oxidized than Al, and a dense oxide layer composed of CeO2 is easily formed on the surface side of the coating 3 of the first unit layer 12. Through these oxide layers, the oxidation resistance of the coating 3 is improved, the reactivity with the workpiece is suppressed, and the coefficient of friction with the workpiece is reduced. Therefore, the cutting tool 1 containing this coating 3 can achieve a long service life under harsh machining conditions where the tool tip temperature easily rises, such as dry machining and machining of difficult-to-machine materials.

[0104] (b1) CeN has a lattice constant of 5.01, which is greater than the lattice constant of CrN (4.15) and AlN (4.12). Therefore, in AlN with added Ce and cubic crystallization... a Cr 1-a-b Ce b Strain is introduced into the first unit layer 12 composed of N, which improves the hardness and wear resistance of the first unit layer 12, and the life of the cutting tool 1 containing the first unit layer 12 becomes longer.

[0105] (c1) When comparing a layer composed of nitrides containing Al, Cr, and Ce (hereinafter also referred to as "AlCrCeN layer") with a layer composed of nitrides containing Al and Ti (hereinafter also referred to as "AlTiN layer"), the AlCrCeN layer is less prone to spinoline decomposition at high temperatures. If spinoline decomposition occurs, soft hexagonal AlN precipitates, resulting in a decrease in hardness. The AlCrCeN layer can suppress the decrease in hardness even at high temperatures, exhibiting high compressive residual stress and excellent resistance to chipping. The AlTiN layer exhibits low compressive residual stress and high thermal insulation. The first layer 13 is composed of alternating layers of a first unit layer 12 composed of AlCrCeN layer and a second unit layer 15 composed of AlTiN layer, thus possessing the high hardness of the first unit layer 12 and the high thermal insulation of the second unit layer 15. The low compressive residual stress of the second unit layer 15 is compensated by the high compressive residual stress of the first unit layer 12. Therefore, as a whole, the hardness, thermal insulation and compressive residual stress of the first layer 13 are improved in a balanced manner, and the life of the cutting tool 1 containing the first layer 13 becomes longer.

[0106] (d1) The first layer 13 is composed of alternating layers of first unit layer 12 and second unit layer 15. At the interface between the first unit layer 12 and the second unit layer 15, the composition and lattice are discontinuous. Therefore, when cracks are generated from the surface of the coating 3 during cutting, the propagation of cracks can be suppressed at this interface. Consequently, chipping and defects can be suppressed, and the life of the cutting tool 1 is extended.

[0107] (e1) The first unit layer 12 is composed of Al a Cr 1-a-b Ce b N is composed of, and the second unit layer 15 is composed of Al. c Ti 1-c The composition is N, and a and c satisfy the relationship a > c. Compared with the second unit layer 15, the first unit layer 12 tends to have a higher Al content. By increasing the Al content in the first unit layer 12, the Al content contained in the first layer 13 as a whole can be increased. As a result, the heat-blocking and oxidation resistance of the first layer 13 can be improved, and the life of the cutting tool 1 containing the first layer 13 becomes longer.

[0108] <Cutting Tools>

[0109] like Figure 1 as well as Figure 2As 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 can cover the entire surface of the substrate 2. Furthermore, even if a portion of the substrate 2 is not covered by the coating 3, or if the composition of the coating 3 is partially different, it does not depart from the scope of this embodiment. The coating 3 can also cover at least the portion of the substrate 2 involved in cutting. In this specification, although the portion of the substrate 2 involved in cutting depends on the size and shape of the substrate 2, it refers to the area in the substrate 2 surrounded by an imaginary surface whose distance from the cutting edge line and the perpendicular line from the cutting edge line towards the substrate 2 side along the tangent of the cutting edge line is, for example, any one of 5 mm, 3 mm, 2 mm, 1 mm, or 0.5 mm.

[0110] <Substrate>

[0111] As for the substrate 2, any previously known substrate can be used. For example, the substrate 2 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.

[0112] The substrate 2 is, in particular, a WC-based cemented carbide or a cermet (especially a TiCN-based cermet). Since WC-based cemented carbide or cermet has an excellent balance between hardness and strength, especially at high temperatures, its use as the substrate 2 of the cutting tool 1 can contribute to the long service life of the cutting tool 1.

[0113] <Lamination>

[0114] The coating 3 in the first embodiment includes a first layer 13. By covering the substrate 2, the coating 3 improves the wear resistance, chipping resistance, and other properties of the cutting tool 1, thereby extending the lifespan of the cutting tool 1. It should be noted that the coating 3 may also include other layers in addition to the first layer 13. Such other layers include... Figure 3 as well as Figure 4 Examples include a second layer 16 disposed between the substrate 2 and the first layer 13, and a third layer 14 disposed on the side of the first layer 13 opposite to the substrate 2.

[0115] The overall thickness of the coating 3 can be 0.5 μm or more and 15 μm or less. If the overall thickness of the coating 3 is 0.5 μm or more, it is easy to obtain the effect of extending the life of the cutting tool 1 by setting the coating 3. On the other hand, if the overall thickness of the coating 3 is 15 μm or less, it is less likely to cause cracking in the coating 3 in the early stage of cutting, which can extend the life of the cutting tool 1. The overall thickness of the coating 3 can be determined by observing the cross-section of the coating 3 using a scanning electron microscope (SEM). The specific measurement method is as follows: Cut the cutting tool 1 along the normal direction of the coating 3 to prepare a cross-sectional sample. Observe the cross-sectional sample using SEM. The magnification is set to 5000 to 10000x, and the field of view is set to 100 to 500 μm. 2 In a single field of view, the thickness range of three portions of the coating 3 is measured, and the average thickness range of the three portions is calculated. This average value corresponds to the thickness of the coating 3. The thicknesses of the layers described later are measured using the same method unless otherwise specified.

[0116] The absolute value of the compressive residual stress of the coating 3 can be 6 GPa or less. The compressive residual stress of the coating 3 is a type of internal stress (inherent strain) existing throughout the coating 3, and is expressed as a negative value (unit: GPa in this embodiment). Therefore, a large compressive residual stress means a large absolute value, and a small compressive residual stress means 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.

[0117] If the compressive residual stress of the coating 3 is 0 GPa or less, the propagation of cracks originating from the outermost surface of the coating 3 can be easily suppressed. On the other hand, if the absolute value of the compressive residual stress is 6 GPa or less, the stress is moderate, and the coating 3 can be easily prevented from peeling off from the edge of the cutting tool 1 before cutting begins.

[0118] The compressive residual stress of the coating 3 was measured using an X-ray residual stress apparatus via the sin2ψ method (see pages 54-66 of "X-ray Stress Measurement Method" (Japan Materials Society, published by Yokendo Co., Ltd., 1981).

[0119] The crystal structure of coating 3 can be cubic. If the crystal structure of coating 3 is cubic, the hardness of coating 3 is increased. The individual crystal structures of each layer in coating 3 can be cubic. The crystal structures of coating 3 and its individual layers can be determined using X-ray diffraction equipment known in the art.

[0120] The coating 3 exhibits good performance when its hardness is above 30 GPa and below 55 GPa, and can also be above 35 GPa and below 50 GPa. Therefore, the coating 3 possesses sufficient hardness. The overall hardness of the coating 3 was measured using a nanoindenter (MTS Nano Indenter XP). Specifically, following the method of ISO 14577, the test load was set to 10 mN (1 gf), and the hardness of three locations on the surface of the coating 3 was measured. The average hardness of the three locations was calculated. This average value represents the hardness of the coating 3.

[0121] <First Layer>

[0122] In this embodiment, the first layer 13 is composed of alternating layers of first unit layer 12 and second unit layer 15. This configuration of the first layer 13 as alternating layers of first unit layer 12 and second unit layer 15 allows for observation of the sheet sample containing the coating 3 using a TEM (transmission electron microscope) and confirmation by contrast difference.

[0123] The first unit layer 12 and the second unit layer 15 can be configured at the position closest to the substrate 2. Figure 1 In this configuration, a first unit layer 12 is disposed at the position closest to the substrate 2, i.e., immediately above the substrate 2. Figure 2 In this process, a second unit layer 15 is disposed closest to the substrate 2, i.e., directly above the substrate 2. Both the first unit layer 12 and 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.

[0124] The thickness of the first layer 13 can be greater than 0.5 μm and less than 15 μm. If the thickness of the first layer 13 is greater than 0.5 μm, it exhibits excellent wear resistance in continuous machining. If the thickness of the first layer 13 is less than 15 μm, it exhibits excellent resistance to chipping in interrupted cutting.

[0125] The thickness of the first layer 13 was determined by observing and measuring the cross-section of the coating 3 using a transmission electron microscope (TEM). The specific measurement method is as follows: A cutting tool 1 was used to cut along the normal direction of the coating 3, preparing a thin-slice sample containing the cross-section of the coating 3. The thin-slice sample was observed using TEM. The magnification was set to 20,000–500x, and the measurement field of view was set to 0.0016–80 μm. 2 Within a single field of view, the thickness of three portions of the first layer 13 is measured, and the average thickness of the three portions is calculated. This average value corresponds to the thickness of the first layer 13.

[0126] <Composition of the first unit layer and the composition of the second unit layer>

[0127] The first unit layer 12 consists of Al a Cr 1-a-b Ce b The composition is N, where a is 0.400 or higher and 0.800 or lower, and b is 0.001 or higher and 0.100 or lower. The first unit layer 12 can improve the oxidation resistance and wear resistance of the coating 3. Regarding the lower limit of a, a value of 0.450 is good, a value of 0.500 is even better, and a value of 0.550 is even better. Regarding the upper limit of a, a value of 0.770 is good, a value of 0.750 is even better, and a value of 0.700 is even better. When a is 0.450 or higher and 0.770 or lower, the effect is good; when it is 0.500 or higher and 0.750 or lower, the effect is even better; and when it is 0.550 or higher and 0.700 or lower, the effect is even better. Regarding the lower limit of b, a value of 0.005 is good, a value of 0.010 is even better, and a value of 0.015 is even better. Regarding the upper limit of b, a value of 0.070 yields good results, 0.050 yields even better results, and 0.030 yields even better results. A value between 0.005 and 0.070 yields good results, a value between 0.010 and 0.050 yields even better results, and a value between 0.015 and 0.030 yields even better results.

[0128] In this disclosure, "the first unit layer is composed of Al" a Cr 1-a-b Ce b "N composition" means that, as long as the effect of this disclosure is not impaired, the first unit layer 12 in Al a Cr 1-a-b Ce b In addition to N, unavoidable impurities may also be included. Examples of unavoidable impurities include oxygen and carbon. The overall content of unavoidable impurities in the first unit layer 12 can be greater than 0 atomic% and less than 1 atomic%. In this disclosure, "atomic%" refers to the proportion (%) of the number of atoms relative to the total number of atoms constituting the layer.

[0129] The second unit layer 15 consists of Al c Ti 1-cThe nitrogen (N) content is 0.30 or higher and 0.75 or lower. The second unit layer 15 can improve the heat resistance, oxidation resistance, and toughness of the coating 3. Regarding the lower limit of c, a value of 0.40 yields good results, 0.45 yields even better results, and 0.50 yields even better results. Regarding the upper limit of c, a value of 0.70 yields good results, 0.65 yields even better results, and 0.60 yields even better results. When c is 0.40 or higher and 0.70 or lower, the results are good; when it is 0.45 or higher and 0.65 or lower, the results are even better; and when it is 0.50 or higher and 0.60 or lower, the results are even better.

[0130] In this disclosure, "the second unit layer is composed of Al" c Ti 1-c "N composition" means that, as long as the effect of this disclosure is not impaired, the second unit layer 15 in Al c Ti 1-c In addition to N, unavoidable impurities may also be included. Examples of unavoidable impurities include oxygen and carbon. The overall content of unavoidable impurities in the second unit layer 15 can be greater than 0 atomic percent and less than 1 atomic percent.

[0131] The contents of unavoidable impurities in the first unit layer 12 and the second unit layer 15, as described above (a, b, c), are determined by elemental analysis of the cross-section of the coating 3 using a transmission electron microscope (TEM). The specific determination method is as follows: A cutting tool 1 is used to cut along the normal direction of the coating 3, preparing a thin-film sample containing the cross-section of the coating 3. The thin-film sample is irradiated with an electron beam using an EDS (Energy Dispersive X-ray Spectroscopy) attached to the TEM. The energy and number of characteristic X-rays generated are measured, and elemental analysis is performed on the first unit layer 12 and the second unit layer 15. Five layers of both the first unit layer 12 and the second unit layer 15 are arbitrarily selected for elemental analysis. The average composition of the five first unit layer 12 layers is determined. This average composition corresponds to the composition of the first unit layer 12. The average composition of the five second unit layer 15 layers is determined. This average composition corresponds to the composition of the second unit layer 15. The following was confirmed: as long as the measurement is performed on the same cutting tool 1, the measurement results will not be biased even if the measurement location is arbitrarily selected.

[0132] The conditions a and c above satisfy the relationship a > c. Therefore, the heat-blocking and oxidation resistance of the coating 3 can be improved.

[0133] In this disclosure, the composition A1 of the first unit layer a Cr 1-a-b Ce bIn N, the number of N atoms A N1 The total number of atoms of Al, Cr, and Ce, A M1 The ratio A N1 / A M1 In manufacturing, the density must be within the range of 0.8 to 1.2. In this disclosure, the composition of the second unit layer is Al. c Ti 1-c In N, the number of N atoms A N2 The total number of atoms A relative to Al and Ti M2 The ratio A N2 / A M2 In manufacturing, it must fall within the range of 0.8 to 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 Within the aforementioned scope, the effectiveness of this disclosure will not be impaired.

[0134] <Average thickness of the first unit layer and average thickness of the second unit layer>

[0135] The average thickness of the first unit layer 12 can be 0.002 μm or more and 0.2 μm or less, and the average thickness of the second unit layer 15 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 3. A lower limit of 0.002 μm for the average thickness of the first unit layer 12 results in good performance; 0.005 μm results in even better performance; and 0.01 μm results in even better performance. An upper limit of 0.20 μm for the average thickness of the first unit layer 12 results in good performance; 0.15 μm results in even better performance; and 0.10 μm results in even better performance. An average thickness of 0.005 μm or more and 0.15 μm or less for the first unit layer 12 results in even better performance; and an average thickness of 0.01 μm or more and 0.1 μm or less results in even better performance. The effect is good when the lower limit of the average thickness of the second unit layer 15 is 0.002 μm, even better when it is 0.005 μm, and further improved when it is 0.01 μm. The effect is good when the upper limit of the average thickness of the second unit layer 15 is 0.20 μm, even better when it is 0.15 μm, and further improved when it is 0.10 μm. The effect is even better when the average thickness of the second unit layer 15 is above 0.005 μm and below 0.15 μm, and further improved when it is above 0.01 μm and below 0.10 μm.

[0136] The average thickness of the first unit layer 12 and the average thickness of the second unit layer 15 can be measured using the same method as the method for measuring the thickness of the first layer 13 described above.

[0137] 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 λ1 / λ2 of the thickness λ1 of the first unit layer 12 to the thickness λ2 of the second unit layer 15 can be 1.0 or more and 5.0 or less. The first unit layer 12, in addition to having high oxidation resistance, also has a low thermal conductivity, making it difficult to transfer heat generated during cutting to the substrate 2. If the ratio λ1 / λ2 is 1.0 or more, the proportion of the first unit layer 12 in the coating 3 increases relatively, the Al content in the coating 3 increases, thereby improving the overall thermal insulation of the cutting tool 1. The cutting tool 1 with this coating 3, especially during continuous cutting, exhibits improved wear resistance. If λ1 / λ2 is 1.0 or more, there is a tendency for the toughness of the coating 3 to increase. On the other hand, if λ1 / λ2 is 5.0 or less, there is a tendency to easily obtain the effect of suppressing crack propagation by stacking the first unit layer 12 and the second unit layer 15. When λ1 / λ2 is 1.0 or higher, the effect is good; when it is 1.5 or higher, the effect is even better; when it is 2.0 or higher, the effect is further improved. When λ1 / λ2 is 5.0 or lower, the effect is good; when it is 4.0 or lower, the effect is even better; when it is 3.0 or lower, the effect is further improved. When λ1 / λ2 is 1.0 or higher and 5.0 or lower, the effect is good; when it is 1.5 or higher and 4.0 or lower, the effect is even better; when it is 1.0 or higher and 3.0 or lower, the effect is good; when it is 2.0 or higher and 3.0 or lower, the effect is even better. Figure 5 For the sake of illustration, the thickness of all three first unit layers 12 is represented as λ1, and the thickness of all three second unit layers 15 is represented as λ2. However, as long as the above-mentioned λ1 / λ2 relationship is satisfied between adjacent first unit layers and second unit layers, 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.

[0138] In the first layer 13, the number of layers of both the first unit layer 12 and the second unit layer 15 can be 10 or more and less than 500. Therefore, by stacking the first unit layer 12 and the second unit layer 15, a balanced improvement in hardness and compressive residual stress can be achieved. In the first layer 13, the effect is even better when the number of layers of both the first unit layer 12 and the second unit layer 15 is 100 or more and less than 400, and further improved when it is 200 or more and less than 350.

[0139] In the first layer 13, the number of layers of the first unit layer 12 and the second unit layer 15 can be determined by using a TEM (transmission electron microscope) to observe the cross-sectional thin sheet sample of the coating 3 at a magnification of 20,000 to 5 million times.

[0140] <Second Layer>

[0141] like Figure 3 as well as Figure 4 As shown, the coating 3 further includes a second layer 16 disposed between the substrate 2 and the first layer 13. The composition of the second 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.

[0142] When the composition of the second layer 16 is the same as that of the first unit layer 12, even if the substrate 2 is exposed in the early stage of cutting, oxidation from the interface between the substrate 2 and the coating 3 can be suppressed.

[0143] 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 can be greater than the thickness of the first unit layer 12. This further improves the adhesion between the substrate 2 and the coating 3. Furthermore, even if the substrate 2 is exposed during the initial cutting stage, oxidation from the interface between the substrate 2 and the coating 3 can be further suppressed. "The thickness of the second layer is greater than the thickness of the first unit layer" can be expressed in other words as "the thickness of the second layer is greater than 1.0 times the thickness of the first unit layer." A thickness of 2.0 times or more than the thickness of the first unit layer 12 results in good effects; 4.0 times or more results in even better effects; and 10.0 times or more results in even better effects. A thickness of 500 times or less than the thickness of the first unit layer 12 results in good effects; 120 times or less results in even better effects; and 50 times or less results in even better effects. When the thickness of the second layer 16 is more than 2.0 times and less than 500 times the thickness of the first unit layer 12, the effect is good; when it is more than 4.0 times and less than 120 times, the effect is even better; and when it is more than 10.0 times and less than 50 times, the effect is even better.

[0144] 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 can be 0.1 μm or more. If the thickness of the second layer 16 is less than 0.1 μm, it tends to be difficult to achieve the effect of suppressing oxidation from the interface between the substrate 2 and the coating 3 by setting the composition of the second layer 16 to be the same as that of 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 effect is better when the thickness of the second layer 16 is 0.3 μm or more, and the effect is further improved when it is 0.4 μm or more. There is no particular upper limit to the thickness of the second layer 16, but if it is greater than 2 μm, grain enlargement occurs and grain boundaries are generated, which tends to make it difficult to further improve the above-mentioned oxidation suppression effect. Therefore, considering the cost, the thickness of the second layer 16 can be set to 2 μm or less.

[0145] When the composition of the second layer 16 is the same as that of the first unit layer 12, such as Figure 3 As shown, the first unit layer 12 can also be stacked immediately above the second layer 16. Additionally, as... Figure 4 As shown, a second unit layer 15 can also be stacked immediately above the second layer 16. When the composition of the second layer 16 is the same as that of the first unit layer 12 and the first unit layer 12 is stacked immediately above the second layer 16, the second layer 16 and the first unit layer 12 have a continuous crystal structure.

[0146] When the composition of the second layer 16 is the same as that of the second unit layer 15, the second unit layer 15 tends to have low stress. Therefore, especially in intermittent machining such as milling and end milling where the tool tip is repeatedly loaded, the peel resistance of the coating 3 can be improved.

[0147] 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 can be greater than the thickness of the second unit layer 15. This further improves the peel resistance of the coating 3, especially in intermittent machining processes such as milling and end milling where repeated loads are applied to the tool tip. "The thickness of the second layer is greater than the thickness of the second unit layer" can be expressed as "the thickness of the second layer is greater than 1.0 times the thickness of the second unit layer." A thickness of 2.0 times or more than the thickness of the second unit layer 15 results in good performance; 4.0 times or more results in even better performance; and 10.0 times or more results in even better performance. A thickness of 500 times or less than the thickness of the second unit layer 15 results in good performance; 120 times or less results in even better performance; and 50 times or less results in even better performance. The effect is good when the thickness of the second layer 16 is more than 2.0 times and less than 500 times the thickness of the second unit layer 15; the effect is even better when it is more than 4.0 times and less than 120 times the thickness; and the effect is even better when it is more than 10.0 times and less than 50 times the thickness.

[0148] When the composition of the second layer 16 is the same as that of the second unit layer 15, the effect is good when the thickness of the second layer 16 is 0.1 μm or more. If the thickness of the second layer 16 is less than 0.1 μm, it tends to be difficult to obtain the effect of improving peel resistance by setting the composition of the second layer 16 to be the same as that of 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 effect is better when the thickness of the second layer 16 is 0.3 μm or more, and the effect is further improved when it is 0.4 μm or more. There is no particular upper limit to the thickness of the second layer 16, but if it is greater than 2 μm, it tends to be difficult to confirm the further improvement of the aforementioned peel resistance. Therefore, considering the cost, the effect is good when the thickness of the second layer 16 is 2 μm or less.

[0149] If the composition of the second layer 16 is the same as that of the second unit layer 15, such as Figure 3 As shown, the first unit layer 12 can also be stacked immediately above the second layer 16. Additionally, as... Figure 4 As shown, the second unit layer 15 can also be stacked immediately above the second layer 16. When the composition of the second layer 16 is the same as that of the second unit layer 15, and the second unit layer 15 is stacked immediately above the second layer 16, the second layer 16 and the second unit layer 15 have a continuous crystal structure.

[0150] <Third Layer>

[0151] like Figures 1-4As shown, the coating 3 may also include a third layer 14 disposed on the side of the first layer 13 opposite to the substrate 2, and the third layer 14 is composed of AlCrCeCN. This reduces the coefficient of friction of the coating 3, thereby extending the lifespan of the cutting tool 1.

[0152] Generally, carbonitrides tend to have a lower coefficient of friction relative to the workpiece compared to nitrides. This reduction in coefficient of friction is believed to be due to the contribution of carbon atoms. If the coating 3 includes a third layer 14, the coefficient of friction of the coating 3 relative to the workpiece is reduced, thus extending the life of the cutting tool 1.

[0153] In the third layer 14, a predetermined color can be assigned by adjusting the composition ratio of N and C. This allows for an aesthetically pleasing and easily identifiable appearance to the cutting tool 1, which is commercially useful.

[0154] In the third layer 14, the ratio of the number of aluminum atoms N2 to the total number of aluminum, chromium, and cerium atoms N1, N2 / N1, can be greater than 0.4 and less than 0.8. As a result, the tool life of the cutting tool 1 is further improved.

[0155] The effect is good when the thickness of the third layer 14 is 0.1 μm or more. If the thickness of the third layer 14 is 0.1 μm or more, the lubricating effect provided by the third layer 14 is easily obtained. On the other hand, there is no particular upper limit to the thickness of the third layer 14; if it is greater than 2 μm, there is a tendency that the aforementioned lubricating effect cannot be further improved. Therefore, considering cost, the thickness of the third layer 14 can be 2 μm or less.

[0156] <Intermediate Layer>

[0157] 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 intermediate layers include TiAlCeN, AlCrN, AlCrBN, and AlCrSiN. The thickness of the intermediate layer may be set to 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.

[0158] [Second Implementation: Cutting Tool (2)]

[0159] use Figures 6-10 Another embodiment of the cutting tool involved in this disclosure will be described.

[0160] Another embodiment of this disclosure (hereinafter also referred to as the "second embodiment") involves a cutting tool 1 that includes a substrate 2 and a coating 3 disposed on the substrate 2, wherein,

[0161] The coating 3 includes a first layer 1A 13A.

[0162] The first layer 13A is composed of alternating layers of first unit layer 12 and third unit layer 17.

[0163] The first unit layer 12 is composed of Al a Cr 1-a-b Ce b N constitutes,

[0164] The value of 'a' is above 0.400 and below 0.800.

[0165] The value of b is greater than 0.001 and less than 0.100.

[0166] The third unit layer 17 is composed of Al d Ti 1-d-e M e N constitutes,

[0167] M is silicon or boron.

[0168] The value of d is greater than 0.30 and less than 0.75.

[0169] The value of e is greater than 0 and less than 0.05.

[0170] The condition 'a' and the condition 'd' satisfy the relationship a > d.

[0171] The cutting tool 1 of the first embodiment 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.

[0172] (a2) The first unit layer 12 is composed of nitrides containing Al, Cr, and Ce. Al is easily oxidized, thus a dense oxide layer composed of Al2O3 is easily formed on the surface side of the coating 3 of the first unit layer 12. Furthermore, the standard formation energy of Ce oxide is lower than that of Al, so it is more easily oxidized than Al, and a dense oxide layer composed of CeO2 is easily formed on the surface side of the coating 3 of the first unit layer 12. Through these oxide layers, the oxidation resistance of the coating 3 is improved, the reactivity with the workpiece is suppressed, and the coefficient of friction with the workpiece is reduced. Therefore, the cutting tool 1 containing this coating 3 can achieve a long service life under harsh machining conditions where the tool tip temperature easily rises, such as dry machining and machining of difficult-to-machine materials.

[0173] (b2) CeN has a lattice constant of 5.01, which is greater than the lattice constant of CrN (4.15) and AlN (4.12). Therefore, in AlN with added Ce and cubic crystallization... a Cr 1-a-b Ce bStrain is introduced into the first unit layer 12 composed of N, which improves the hardness and wear resistance of the first unit layer 12, and the life of the cutting tool 1 containing the first unit layer 12 becomes longer.

[0174] (c2) When comparing a layer composed of nitrides containing Al, Cr, and Ce (hereinafter also referred to as "AlCrCeN layer") with a layer composed of nitrides containing Al, Ti, and M (M being silicon or boron) (hereinafter also referred to as "AlTiMN layer"), the AlCrCeN layer is less prone to spinoline decomposition at high temperatures. If spinoline decomposition occurs, soft hexagonal AlN precipitates, resulting in a decrease in hardness. The AlCrCeN layer can suppress the decrease in hardness even at high temperatures, exhibiting high compressive residual stress and excellent resistance to chipping. The AlTiMN layer exhibits low compressive residual stress and high thermal insulation properties. The first layer 1A 13A is composed of alternating layers of a first unit layer 12 composed of AlCrCeN layer and a third unit layer 17 composed of AlTiMN layer, thus possessing the high hardness of the first unit layer 12 and the high thermal insulation properties of the third unit layer 17. The low compressive residual stress of the third unit layer 17 is compensated by the high compressive residual stress of the first unit layer 12. Therefore, as a whole, the hardness, thermal insulation and compressive residual stress of the first A layer 13A are improved in a balanced manner, and the cutting tool 1 containing the first A layer 13A has a longer service life.

[0175] (d2) The first layer 13A is composed of alternating layers of first unit layer 12 and third unit layer 17. At the interface between the first unit layer 12 and the third unit layer 17, the composition and lattice are discontinuous. Therefore, when cracks are generated from the surface of the coating 3 during cutting, the propagation of cracks can be suppressed at this interface. Consequently, chipping and defects can be suppressed, and the life of the cutting tool 1 is extended.

[0176] (e2) The first unit layer 12 is composed of Al a Cr 1-a-b Ce b N is composed of, and the third unit layer 17 is composed of Al. d Ti 1-d-e M e The N composition, a and d satisfy the relationship a > d. Compared with the third unit layer 17, the first unit layer 12 tends to have a higher Al content. By increasing the Al content in the first unit layer 12, the Al content contained in the entire first A layer 13A can be increased. As a result, the heat-blocking and oxidation resistance of the first A layer 13A can be improved, and the life of the cutting tool 1 containing the first A layer 13A becomes longer.

[0177] The cutting tool 1 of the second embodiment can be configured to be basically the same as the cutting tool 1 of the first embodiment, except for the configuration of the first layer 13A and the second layer 16. Hereinafter, the "first layer 1A" and the "second layer" will be described.

[0178] <Level 1A>

[0179] In this embodiment, the first layer 13A is composed of alternating layers of first unit layer 12 and third unit layer 17. Because the first layer 13A is composed of alternating layers of first unit layer 12 and third unit layer 17, the cross-section of the coating 3 can be observed using a TEM (transmission electron microscope), and confirmed by the difference in contrast. The thickness of the first layer 13A can be set to be the same as the thickness of the first layer 13 described in the first embodiment.

[0180] <Composition of the first unit layer and the composition of the third unit layer>

[0181] The composition of the first unit layer 12 in the second embodiment A1 a Cr 1-a-b Ce b N can be set to the composition Al of the first unit layer 12 in the first embodiment. a Cr 1-a-b Ce b N is the same.

[0182] The third unit layer 17 is composed of Al d Ti 1-d-e M e The structure consists of N, where M is silicon or boron, d is greater than 0.30 and less than 0.75, and e is greater than 0 and less than 0.05. The third unit layer 17 possesses both excellent hardness and excellent oxidation resistance. The reasoning is speculated as follows.

[0183] When M is boron, the hardness of the third unit layer 17 increases due to boron, and the overall hardness of the coating 3 increases. Furthermore, the boron oxide formed by oxidation of the cutting tool 1 surface during cutting densifies the Al oxide in the third unit layer 17, thereby improving the oxidation resistance of the third unit layer 17. In addition, since boron oxide has a low melting point, it acts as a lubricant during cutting, suppressing the solidification of the material being cut.

[0184] When M is silicon, the microstructure of the third unit layer 17 is refined, thereby improving the hardness and oxidation resistance of the third unit layer 17, and improving the overall hardness and oxidation resistance of the coating 3.

[0185] The aforementioned d is 0.30 or higher and 0.75 or lower. As a result, the crystal structure of the third unit layer 17 is formed into a cubic crystal form, the third unit layer 17 has increased hardness, and the wear resistance of the third unit layer 17 is improved. When the lower limit of d is 0.35, the effect is good; when it is 0.40, the effect is even better; and when it is 0.45, the effect is even better. When the upper limit of d is 0.75, the effect is good; when it is 0.70, the effect is even better; and when it is 0.65, the effect is even better. When d is 0.35 or higher and 0.75 or lower, the effect is good; when it is 0.40 or higher and 0.70 or lower, the effect is even better; and when it is 0.45 or higher and 0.65 or lower, the effect is even better.

[0186] The value of e is greater than 0 and less than 0.05. This improves the hardness and oxidation resistance of the first layer 13. A lower limit of e of 0.002 results in good performance, 0.005 in even better performance, and 0.01 in even better performance. A value of e less than 0.04 results in good performance, less than 0.03 in even better performance, and less than 0.02 in even better performance. A value of e greater than 0.002 and less than 0.05 results in good performance, greater than 0.005 and less than 0.03 in even better performance, and greater than 0.01 and less than 0.02 in even better performance.

[0187] In this disclosure, "the third unit layer is composed of Al" d Ti 1-d-e M e "N composition" means that, as long as the effect of this disclosure is not impaired, the third unit layer 17 in Al d Ti 1-d-e M e In addition to N, it can also contain unavoidable impurities. Examples of such unavoidable impurities include oxygen and carbon. The overall content of unavoidable impurities in the third unit layer 17 can be greater than 0 atomic percent and less than 1 atomic percent.

[0188] The content of unavoidable impurities in d, e, and the third unit layer 17 mentioned above was determined by the same method as that used in a. It should be noted that the following condition has been confirmed: as long as the same cutting tool 1 is used for the measurement, the measurement results will not be biased even if the measurement site is arbitrarily selected.

[0189] The above-mentioned 'a' and 'd' satisfy the relationship a > d. Therefore, the heat-blocking and oxidation resistance of the coating 3 can be improved.

[0190] In this disclosure, the composition A1 of the first unit layer a Cr 1-a-b Ce b In N, the number of N atoms A N1The total number of atoms of Al, Cr, and Ce, A M1 The ratio A N1 / A M1 In manufacturing, the density must be within the range of 0.8 to 1.2. In this disclosure, the composition of the third unit layer is Al. d Ti 1-d-e M e In N, the number of N atoms A N3 The total number of atoms A relative to Al, Ti, and M M3 The ratio A N3 / A M3 In manufacturing, it must fall within the range of 0.8 to 1.2. Compared to A... N1 / A M1 And compared to A N3 / A M3 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 N3 / A M3 If the contents fall within the above-mentioned range, the effect of this disclosure will not be impaired.

[0191] <Average thickness of the first unit layer and average thickness of the third unit layer>

[0192] Alternatively, the average thickness of the first unit layer 12 can be 0.002 μm or more and 0.2 μm or less, and the average thickness of the third unit layer 17 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 3. A lower limit of 0.002 μm for the average thickness of the first unit layer 12 is effective; 0.005 μm is even more effective; and 0.01 μm is even more effective. An upper limit of 0.20 μm for the average thickness of the first unit layer 12 is effective; 0.15 μm is even more effective; and 0.10 μm is even more effective. A first unit layer 12 with an average thickness of 0.005 μm or more and 0.15 μm or less is even more effective; and a first unit layer 12 with an average thickness of 0.01 μm or more and 0.1 μm or less is even more effective. The effect is good when the lower limit of the average thickness of the third unit layer 17 is 0.002 μm, even better when it is 0.005 μm, and further improved when it is 0.01 μm. The effect is good when the upper limit of the average thickness of the third unit layer 17 is 0.20 μm, even better when it is 0.15 μm, and further improved when it is 0.10 μm. The effect is even better when the average thickness of the third unit layer 17 is above 0.005 μm and below 0.15 μm, and further improved when it is above 0.01 μm and below 0.10 μm.

[0193] The average thickness of the first unit layer 12 and the average thickness of the third unit layer 17 can be determined using the same method as the method for measuring the thickness of the first layer 13 described above.

[0194] 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 λ1 / λ3 of the thickness λ1 of the first unit layer 12 to the thickness λ3 of the third unit layer 17 can be 1.0 or more and 5.0 or less. The first unit layer 12, in addition to having high oxidation resistance, also has a low thermal conductivity, making it difficult to transfer heat generated during cutting to the substrate 2. If the ratio λ1 / λ3 is 1.0 or more, the proportion of the first unit layer 12 in the coating 3 increases relatively, the Al content in the coating 3 increases, thereby improving the overall thermal insulation of the cutting tool 1. The cutting tool 1 with this coating 3, especially during continuous cutting, exhibits improved wear resistance. If λ1 / λ3 is 1.0 or more, there is a tendency for the toughness of the coating 3 to increase. On the other hand, if λ1 / λ3 is 5.0 or less, there is a tendency to easily obtain the effect of suppressing crack propagation by stacking the first unit layer 12 and the third unit layer 17. When λ1 / λ3 is 1.0 or higher, the effect is good; when it is 1.5 or higher, the effect is even better; when it is 2.0 or higher, the effect is further improved. When λ1 / λ3 is 5.0 or lower, the effect is good; when it is 4.0 or lower, the effect is even better; when it is 3.0 or lower, the effect is further improved. When λ1 / λ3 is 1.0 or higher and 5.0 or lower, the effect is good; when it is 1.5 or higher and 4.0 or lower, the effect is even better; when it is 1.0 or higher and 3.0 or lower, the effect is good; when it is 2.0 or higher and 3.0 or lower, the effect is further improved. Figure 10 For the sake of illustration, the thickness of all three first unit layers 12 is represented as λ1, and the thickness of all three third unit layers 17 is represented as λ3. However, as long as the above λ1 / λ3 relationship is satisfied between adjacent first unit layers and third unit layers, 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.

[0195] In layer 1A 13A, the number of layers stacked for both the first unit layer 12 and the third unit layer 17 can be 10 or more and 500 or less. Therefore, by stacking the first unit layer 12 and the third unit layer 17, there is a tendency to easily achieve a balanced increase in hardness and compressive residual stress. In layer 1A 13A, the effect is even better when the number of layers stacked for both the first unit layer 12 and the third unit layer 17 is 100 or more and 400 or less, and further improved when it is 200 or more and 350 or less.

[0196] In the first layer 1A 13A, the number of stacks of the first unit layer 12 and the third unit layer 17 can be determined by the same method as the method for determining the number of stacks of the first unit layer 12 and the second unit layer 15 described in the first embodiment.

[0197] <Second Layer>

[0198] like Figure 8 as well as Figure 9 As shown, the coating 3 further includes a second layer 16 disposed between the substrate 2 and the first A layer 13A. The composition of the second 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.

[0199] When the composition of the second layer 16 is the same as that of the first unit layer 12, even if the substrate 2 is exposed in the early stage of cutting, oxidation from the interface between the substrate 2 and the coating 3 can be suppressed.

[0200] 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 can be greater than the thickness of the first unit layer 12. This further improves the adhesion between the substrate 2 and the coating 3. Furthermore, even if the substrate 2 is exposed during the initial cutting stage, oxidation from the interface between the substrate 2 and the coating 3 can be further suppressed. "The thickness of the second layer is greater than the thickness of the first unit layer" can be expressed in other words as "the thickness of the second layer is greater than 1.0 times the thickness of the first unit layer." A thickness of 2.0 times or more than the thickness of the first unit layer 12 is effective; a thickness of 4.0 times or more is even more effective; and a thickness of 10.0 times or more is even more effective. A thickness of 500 times or less than the thickness of the first unit layer 12 is effective; a thickness of 120 times or less is even more effective; and a thickness of 50 times or less is even more effective. When the thickness of the second layer 16 is more than 2.0 times and less than 500 times the thickness of the first unit layer 12, the effect is good; when it is more than 4.0 times and less than 120 times, the effect is even better; and when it is more than 10.0 times and less than 50 times, the effect is even better.

[0201] 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 can be 0.1 μm or more. If 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, which is achieved by setting the composition of the second layer 16 to be the same as that of 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 effect is better when the thickness of the second layer 16 is 0.3 μm or more, and the effect is further improved when it is 0.4 μm or more. There is no particular upper limit to the thickness of the second layer 16, but if it is greater than 2 μm, grain enlargement occurs and grain boundaries are formed, which tends to make it difficult to further improve the above-mentioned oxidation suppression effect. Therefore, considering the cost, the effect is good when the thickness of the second layer 16 is 2 μm or less.

[0202] When the composition of the second layer 16 is the same as that of the first unit layer 12, such as Figure 8 As shown, the first unit layer 12 can also be stacked immediately above the second layer 16. Additionally, as... Figure 9 As shown, a second unit layer 15 can also be stacked immediately above the second layer 16. When the composition of the second layer 16 is the same as that of the first unit layer 12, and the first unit layer 12 is stacked immediately above the second layer 16, the second layer 16 and the first unit layer 12 have a continuous crystal structure.

[0203] When the composition of the second layer 16 is the same as that of the third unit layer 17, the third unit layer 17 tends to have low stress. Therefore, especially in intermittent machining such as milling and end milling where the tool tip is repeatedly loaded, the peel resistance of the coating 3 can be improved.

[0204] When the composition of the second layer 16 is the same as that of the third unit layer 17, the thickness of the second layer 16 can be greater than the thickness of the third unit layer 17. Therefore, especially in intermittent machining processes such as milling and end milling where the tool tip is repeatedly subjected to load, the peel resistance of the coating 3 can be further improved. "The thickness of the second layer is greater than the thickness of the third unit layer" can be expressed in other words as "the thickness of the second layer is greater than 1.0 times the thickness of the third unit layer." When the thickness of the second layer 16 is 2.0 times or more than the thickness of the third unit layer 17, the effect is good; when it is 4.0 times or more, the effect is even better; and when it is 10.0 times or more, the effect is even better. When the thickness of the second layer 16 is less than 500 times the thickness of the third unit layer 17, the effect is good; when it is less than 120 times, the effect is even better; and when it is less than 50 times, the effect is even better. When the thickness of the second layer 16 is more than 2.0 times and less than 500 times the thickness of the third unit layer 17, the effect is good; when it is more than 4.0 times and less than 120 times, the effect is even better; and when it is more than 10.0 times and less than 50 times, the effect is even better.

[0205] When the composition of the second layer 16 is the same as that of the third unit layer 17, a thickness of 0.1 μm or more for the second layer 16 yields good results. If the thickness of the second layer 16 is less than 0.1 μm, it tends to be difficult to obtain the improved peel resistance effect achieved by setting the composition of the second layer 16 to be the same as that of the third unit layer 17. When the composition of the second layer 16 is the same as that of the third unit layer 17, a thickness of 0.3 μm or more for the second layer 16 yields even better results, and a thickness of 0.4 μm or more yields even better results. There is no particular upper limit to the thickness of the second layer 16, but if it is greater than 2 μm, it tends to be difficult to confirm the aforementioned further improvement in peel resistance. Therefore, considering cost, a thickness of 2 μm or less for the second layer 16 yields good results.

[0206] If the composition of the second layer 16 is the same as that of the third unit layer 17, such as Figure 8 As shown, the first unit layer 12 can also be stacked immediately above the second layer 16. Additionally, as... Figure 9 As shown, a third unit layer 17 can also be stacked immediately above the second layer 16. When the composition of the second layer 16 is the same as that of the third unit layer 17, and the third unit layer 17 is stacked immediately above the second layer 16, the second layer 16 and the third unit layer 17 have a continuous crystal structure.

[0207] [Implementation Method 3: Method for Manufacturing a Cutting Tool]

[0208] In Embodiment 3, a method for manufacturing the cutting tool 1 according to the first or second embodiment will be described. This 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 a first layer 13 or a first A layer 13A. The details of each step will be described below.

[0209] <First Process>

[0210] In the first step, substrate 2 is prepared. Substrate 2 may be the substrate 2 described in the first embodiment.

[0211] When using cemented carbide as the substrate 2, commercially available substrates can be used, or it can be manufactured using conventional powder metallurgy. In the case of manufacturing using conventional powder metallurgy, WC powder and Co powder are mixed using a ball mill or similar method to obtain a mixed powder. After drying the mixed powder, it is shaped into a predetermined shape to obtain a molded body. Further, the molded body is sintered to obtain a WC-Co based cemented carbide (sintered body). Then, by performing predetermined tool tip machining such as honing on the sintered body, a substrate made of WC-Co based cemented carbide can be manufactured. Even substrates other than those mentioned above, as long as they are conventionally known substrates, can be prepared.

[0212] <Second Process>

[0213] In the second process, a coating 3 is formed on the substrate 2. The second process includes the process of forming a first layer 13 or a first A layer 13A.

[0214] In the "step of forming the first layer", the first layer 13 is formed by alternately layering the first unit layer 12 and the second unit layer 15 using physical vapor deposition (PVD). In the "step of forming the first A layer", the first unit layer 12 and the third unit layer 17 are alternately layered using PVD to form the first A layer 13A. To improve the wear resistance of the coating 3 containing the first layer 13 or the first A layer 13A, forming a layer composed of a highly crystalline compound is effective. The inventors of this invention studied various methods for forming the first layer 13 and the first layer 13A and found that physical vapor deposition is particularly effective.

[0215] 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 can be used. In particular, cathodic arc ion plating, which has a high ionization rate of the raw material element, can be used. When using cathodic arc ion plating, the surface of the substrate 2 can be subjected to metal ion bombardment treatment before forming the first layer 13 or the first A layer 13A, thus significantly improving the adhesion between the substrate 2 and the coating 3 containing the first layer 13 or the first A layer 13A.

[0216] Cathodic arc ion plating can be carried out, for example, by setting a substrate 2 in a device and setting a target as a cathode, applying a high voltage to the target to generate an arc discharge, thereby ionizing and evaporating the atoms constituting the target, and depositing the material on the substrate 2.

[0217] Balanced magnetron sputtering can be performed, for example, by placing a substrate 2 inside a device and placing a target 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 2 to generate a gas plasma, causing the gas ions generated by the gas plasma to collide with the target, and causing the atoms released from the target to accumulate on the substrate 2.

[0218] 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. HiPIMS, which allows for the application of high voltage to obtain dense films, can also be used.

[0219] <Other processes>

[0220] The second process, in addition to the process of forming the first layer 13 or the first A layer 13A, may also include surface treatment processes such as surface grinding and shot peening. Furthermore, the second process may include processes for forming other layers such as the second layer 16, the third layer 14, and intermediate layers. 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 within a single physical vapor deposition apparatus along with the first unit layer 12, the second unit layer 15, or the third unit layer 17, physical vapor deposition yields excellent results.

[0221] Example

[0222] The present embodiment will be further described in detail through the examples. However, the present embodiment is not limited to these examples.

[0223] [Example 1]

[0224] <Sample 1-1 to Sample 1-24, Sample 1-101 to Sample 1-109>

[0225] Making Cutting Tools

[0226] Figure 11 This is a schematic cross-sectional view of the cathode arc ion plating apparatus used in this embodiment. Figure 12 yes Figure 11 A top view of the device.

[0227] exist Figure 11 as well as Figure 12 In the apparatus, a first unit layer cathode 106, a second unit layer cathode 107, and a third layer cathode 120, which are alloy targets and serve as the metal raw material for the coating 3, are installed in chamber 101, along with a rotating substrate holder 104 for setting the substrate. In the apparatus used in samples 1-22 to 1-24, a second layer cathode (not shown) is also installed in chamber 101. The composition of the second layer cathode is adjusted in a manner that yields the compositions of the second layer in Tables 1 and 2. An arc power supply 108 is installed in cathode 106, and an arc power supply 109 is installed in cathode 107. Additionally, a bias power supply 110 is installed in substrate holder 104. Furthermore, a gas inlet 105 for introducing gas is provided in chamber 101, and a gas outlet 103 is provided for adjusting the pressure inside chamber 101, forming a structure in which gas inside chamber 101 can be drawn from the gas outlet 103 using a vacuum pump.

[0228] A chip of JIS standard CNMG120408 and a chip of SEMT13T3AGSN manufactured by Sumitomo Electric Industries, Ltd. are mounted on the substrate holder 104 as a substrate.

[0229] Next, a vacuum pump is used to reduce the pressure inside chamber 101, and while the substrate is rotated, a heater installed in the device is used to heat the temperature to 500°C. Vacuuming is then performed until the pressure inside chamber 101 becomes 1.0 × 10⁻⁶. -4 Next, argon gas was introduced through the gas inlet to maintain the pressure inside chamber 101 at 2.0 Pa. While gradually increasing the voltage of the bias power supply 110 to -1000V, the surface of the substrate was cleaned for 15 minutes. Afterward, the argon gas was discharged from chamber 101, thereby cleaning the substrate (argon bombardment treatment). Through the above, the substrate for the cutting tools of each sample was prepared.

[0230] Next, while rotating the substrate in the center, nitrogen gas is introduced as the reactant gas. Simultaneously, the substrate temperature is maintained at 500°C, the reactant gas pressure is maintained at 2.0 Pa, and the bias power supply 110 voltage is maintained within a certain range of -50V to -200V. An arc current of 120A is supplied to cathodes 106 and 107 respectively, generating metal ions from cathodes 106 and 107, thus forming a second layer and a first layer with the compositions shown in Tables 1 and 2 on the substrate. It should be noted that the composition of cathode 106 is adjusted to obtain the composition of the first unit layer shown in Tables 1 and 2. Furthermore, the composition of cathode 107 is adjusted to obtain the composition of the second unit layer shown in Tables 1 and 2.

[0231] When a second layer is formed, the first layer is formed by alternately stacking first and second unit layers on the second layer with the layer stack numbers shown in Tables 1 and 2, respectively. When a second layer is not formed, the first layer is formed by alternately stacking first and second unit layers on the substrate with the layer stack numbers shown in Tables 1 and 2, respectively. Furthermore, the thickness of the second layer, the thickness of each of the first and second unit layers in the first layer, and the layer stack number are adjusted by the rotation speed of the substrate. Then, when the thicknesses of the second and first layers reach the thicknesses shown in Tables 1 and 2, respectively, the current supplied to the evaporation source is stopped.

[0232] Next, while introducing nitrogen and methane gas as reactant gases into chamber 101, an arc current of 100A was supplied to cathode 120 while maintaining the substrate temperature at 400°C, the reactant gas pressure at 2.0 Pa, and the bias power supply 110 voltage at -300V. This generated metal ions from cathode 120, forming a third layer on top of the first layer. When the thickness of the third layer reached the thicknesses shown in Tables 1 and 2, the current supplied to the evaporation source was stopped. It should be noted that the composition of cathode 120 was adjusted to obtain the composition of the third layer shown in Tables 1 and 2. The amounts of nitrogen and methane gas introduced were also adjusted to obtain the composition of the third layer shown in Tables 1 and 2. Based on the above, cutting tools for each sample were fabricated.

[0233]

[0234]

[0235] "evaluate"

[0236] For 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, 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, and λ1 / λ2 were measured for the cutting tools involved.

[0237] <Determination of the composition of the first unit layer>

[0238] For each sample's cutting tool, the composition of the first unit layer was determined using the method described in the first embodiment to obtain Al. a Cr 1-a-b Ce b The values ​​of a and b in N are recorded in the "a" and "b" columns of "First Unit Layer" in Tables 1 and 2. In Tables 1 and 2, a "-" in the "a" and "b" columns indicates that the first unit layer does not exist.

[0239] <Determination of the composition of the second unit layer>

[0240] For each sample's cutting tool, the composition of the second unit layer was determined using the method described in the first embodiment, yielding Al. c Ti 1-c The value of c in N. Record the result in the "c" column of "Second Unit Layer" in Table 1 and Table 2. In Table 1 and Table 2, a "-" in the "c" column indicates that there is no second unit layer.

[0241] <Determination of the composition of the second and third layers>

[0242] For each sample's cutting tool, the composition of the second and third layers was determined using the method described in the first embodiment. The results were recorded in the "Composition" column for the "Second Layer" and the "Composition" column for the "Third Layer" in Tables 1 and 2. A "-" in the "Composition" column for the "Second Layer" in Tables 1 and 2 indicates that the second layer does not exist, and a "-" in the "Composition" column for the "Third Layer" indicates that the third layer does not exist.

[0243] <Determination of the number of layers>

[0244] For each sample cutting tool, the number of layers in the first unit layer and the second unit layer is determined using the method described in the first embodiment. For example, a layer count of 10 indicates that the first unit layer has 10 layers and the second unit layer has 10 layers. The results are recorded in the "Number of Layers" column of "First Layer" in Tables 1 and 2, respectively.

[0245] <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>

[0246] 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 second layer, and the thickness of the third layer were determined using the method described in the first embodiment. The results were recorded in the "Average Thickness [μm]" column for the "First Unit Layer," the "Average Thickness [μm]" column for the "Second Unit Layer," the "Thickness [μm]" column for the "First Layer," and the "Thickness [μm]" column for the "Second Layer" in Tables 1 and 2. A "-" value in the "Thickness [μm]" column for the "Second Layer" in Tables 1 and 2 indicates that the second layer does not exist. A "-" value in the "Thickness [μm]" column for the "Thickness [μm]" in Tables 1 and 2 indicates that the third layer does not exist.

[0247] <Determination of λ1 / λ2>

[0248] For the cutting tools of each sample, λ1 / λ2 was calculated using the method described in the first embodiment. The results were recorded in the "λ1 / λ2" column of Table 1 and Table 2, respectively. It should be noted that a "-" is recorded in the "λ1 / λ2" column of Table 1 and Table 2, indicating that at least one of the first unit layer and the second unit layer does not exist.

[0249] <Cutting Test 1: Continuous Turning Test>

[0250] For each CNMG120408 shaped cutting tool, a dry continuous turning test was 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 Tables 1 and 2. A longer cutting time indicates a longer tool life.

[0251] Cutting Conditions

[0252] • Material to be cut: SCM440 (HB=300)

[0253] • Cutting speed: 250m / min

[0254] • Feed rate: 0.3 mm / rev

[0255] • Incision: 2.0mm

[0256] • Coolant: Dry

[0257] The cutting process performed under the above cutting conditions is a high-speed and high-efficiency machining of difficult-to-cut materials, which is equivalent to the cutting process performed under conditions of high tool tip temperature.

[0258] The cutting tools of Specimens 1-1 to 1-24 correspond to the Examples, and the cutting tools of Specimens 1-101 to 1-109 correspond to the Comparative Examples. It was confirmed that the cutting tools of Specimens 1-1 to 1-24 have a longer tool life in cutting operations performed under high tool tip temperature conditions compared to the cutting tools of Specimens 1-101 to 1-109.

[0259] <Cutting Test 2: Milling Test>

[0260] For the cutting tool of the SEMT13T3AGSN shape of each sample, the centerline of a 150mm wide plate made of a difficult-to-machine material and the width of the plate are... With the tool center aligned, surface milling was performed under the following cutting conditions, and the cutting length was measured until the wear on the flank face of the tool tip reached 0.2 mm. The results were recorded in the "Cutting Length [km]" column of "Cutting Test 2" in Table 1 and Table 2. A longer cutting length indicates a longer tool life.

[0261] Cutting Conditions

[0262] Material to be cut: SKD11 (HB=235)

[0263] • Cutting speed: 180m / min

[0264] • Feed rate: 0.15mm / t

[0265] • Axial cut ap: 1.5mm

[0266] Radial notch ae: 150mm

[0267] • Coolant: Dry

[0268] The cutting operations performed under the above cutting conditions are high-speed, high-efficiency milling operations on difficult-to-cut materials and under dry conditions, which is equivalent to cutting operations performed under conditions of high tool tip temperature.

[0269] The cutting tools of Specimens 1-1 to 1-24 correspond to the Examples, and the cutting tools of Specimens 1-101 to 1-109 correspond to the Comparative Examples. It was confirmed that the cutting tools of Specimens 1-1 to 1-24 have a longer tool life in cutting operations performed under high tool tip temperature conditions compared to the cutting tools of Specimens 1-101 to 1-109.

[0270] [Example 2]

[0271] <Samples 2-1 to 2-19, Samples 2-101 to 2-111>

[0272] Making Cutting Tools

[0273] Substrates for each sample were prepared using the same method as in Example 1. While the substrate was rotated in the center, nitrogen gas was introduced as the reactant gas. Simultaneously, the substrate temperature was maintained at 500°C, the reactant gas pressure at 2.0 Pa, and the bias power supply 110 voltage was maintained within a certain range of -50V to -200V. An arc current of 120A was supplied to cathodes 106 and 107, respectively, thereby generating metal ions from cathodes 106 and 107, forming a second layer and a first A layer with the compositions shown in Tables 3 and 4 on the substrate. It should be noted that the composition of cathode 106 was adjusted to obtain the composition of the first unit layer shown in Tables 3 and 4. Furthermore, the composition of cathode 107 was adjusted to obtain the composition of the third unit layer shown in Tables 3 and 4.

[0274] When a second layer is formed, layer 1A is formed by alternately stacking first and third unit layers on the second layer with the layer stack numbers shown in Tables 3 and 4, respectively. When a second layer is not formed, layer 1A is formed by alternately stacking first and third unit layers on the substrate with the layer stack numbers shown in Tables 3 and 4. Furthermore, the thickness of the second layer, the thickness of each of the first and third unit layers in layer 1A, and the layer stack number are adjusted by the rotation speed of the substrate. Then, when the thicknesses of the second layer and layer 1A reach the thicknesses shown in Tables 3 and 4, respectively, the current supplied to the evaporation source is stopped.

[0275] Next, while introducing nitrogen and methane gas as reactant gases into chamber 101, an arc current of 100A was supplied to cathode 120 while maintaining the substrate temperature at 400°C, the reactant gas pressure at 2.0 Pa, and the bias power supply 110 voltage at -300V. This generated metal ions from cathode 120, forming a third layer on top of layer 1A. When the thickness of the third layer reached the thicknesses shown in Tables 3 and 4, the current supplied to the evaporation source was stopped. It should be noted that the composition of cathode 120 was adjusted to obtain the composition of the third layer shown in Tables 3 and 4. The amounts of nitrogen and methane gas introduced were also adjusted to obtain the composition of the third layer shown in Tables 3 and 4. Based on the above, cutting tools for each sample were fabricated.

[0276]

[0277]

[0278] "evaluate"

[0279] For each sample and the cutting tool involved, the composition of the first unit layer, the composition of the third unit layer, the composition of the second layer, the composition of the third layer, the number of layers, 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 layer, the thickness of the third layer, and λ1 / λ3 were measured. The measurement methods for each item are as described in Example 1. The results are shown in Tables 3 and 4.

[0280] <Cutting Test 3: Continuous Turning Test>

[0281] For each CNMG120408 shaped cutting tool, a dry continuous turning test was 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 3 and 4. It should be noted that in Tables 3 and 4, a longer cutting time indicates a longer tool life.

[0282] (Cutting conditions)

[0283] • Material being cut: Chromium-nickel-iron alloy 718 (aging material: HB=400)

[0284] • Cutting speed: 65m / min

[0285] • Feed rate: 0.15mm / rev

[0286] • Incision: 1.0mm

[0287] • Coolant: Dry

[0288] The cutting process performed under the above cutting conditions is a high-speed and high-efficiency machining of difficult-to-cut materials, which is equivalent to the cutting process performed under conditions of high tool tip temperature.

[0289] The cutting tools of specimens 2-1 to 2-19 correspond to the examples, and the cutting tools of specimens 2-101 to 2-111 correspond to the comparative examples. It was confirmed that the cutting tools of specimens 2-1 to 2-19 have a longer tool life in cutting operations performed under high tool tip temperature conditions compared to the cutting tools of specimens 2-101 to 2-111.

[0290] <Cutting Test 4: Milling Test>

[0291] For the cutting tool of the SEMT13T3AGSN shape of each sample, the centerline of a 150mm wide plate made of a difficult-to-machine material and the width of the plate are... With the tool center aligned, surface milling was performed under the following cutting conditions, and the cutting length was measured until the wear on the flank face of the tool tip reached 0.2 mm. The results were recorded in the "Cutting Length [km]" column of "Cutting Test 4" in Tables 3 and 4. It should be noted that in Tables 3 and 4, a longer cutting length indicates a longer tool life.

[0292] Cutting Conditions

[0293] • Material to be cut: FCD700 (HB=250)

[0294] • Cutting speed: 250m / min

[0295] • Feed rate: 0.2 mm / t

[0296] • Axial cut ap: 2.0mm

[0297] Radial notch ae: 150mm

[0298] • Coolant: Dry

[0299] The cutting operations performed under the above cutting conditions are high-speed, high-efficiency milling operations on difficult-to-cut materials and under dry conditions, which is equivalent to cutting operations performed under conditions of high tool tip temperature.

[0300] The cutting tools of specimens 2-1 to 2-19 correspond to the examples, and the cutting tools of specimens 2-101 to 2-111 correspond to the comparative examples. It was confirmed that the cutting tools of specimens 2-1 to 2-19 have a longer tool life in cutting operations performed under high tool tip temperature conditions compared to the cutting tools of specimens 2-101 to 2-111.

[0301] 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.

[0302] 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.

[0303] Explanation of reference numerals in the attached figures

[0304] 1: Cutting tool; 2: Substrate; 3: Coating; 12: First unit layer; 13: First layer; 13A: 1A layer; 14: Third layer; 15: Second unit layer; 16: Second layer; 17: Third unit layer; 101: Chamber; 103: Gas outlet; 104: Substrate holder; 105: Gas; 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 is made of Al a Cr 1-a-b Ce b N The value of a is greater than 0.400 and less than 0.

800. The value of b is greater than 0.001 and less than 0.

100. The second unit layer is composed of Al c Ti 1-c N The value of c is greater than 0.30 and less than 0.

75. The relationship between 'a' and 'c' is a > c. In the first unit layer and the second unit layer adjacent to the first unit layer, the ratio of the thickness λ1 of the first unit layer to the thickness λ2 of the second unit layer, λ1 / λ2, is 1.1 or more and 5.0 or less.

2. The cutting tool according to claim 1, 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.

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

4. The cutting tool according to claim 3, wherein, The composition of the second layer is the same as that of the first unit layer. The second layer is thicker than the first unit layer.

5. The cutting tool according to claim 3, wherein, The composition of the second layer is the same as that of the second unit layer. The thickness of the second layer is greater than the thickness of the second unit layer.

6. The cutting tool according to any one of claims 1 to 5, wherein, The coating further includes a third layer disposed on the side of the first layer opposite to the substrate. The third layer is composed of AlCrCeCN.

7. A cutting tool comprising a substrate and a coating disposed on the substrate, wherein, The coating comprises a first A layer. The first A layer is composed of alternating layers of first unit layers and third unit layers. The first unit layer is composed of Al a Cr 1-a-b Ce b N The value of a is greater than 0.400 and less than 0.

800. The value of b is greater than 0.001 and less than 0.

100. The third unit layer is made of Al d Ti 1-d-e M e N M is silicon or boron. The value of d is greater than 0.30 and less than 0.

75. The value of e is greater than 0 and less than 0.

05. The relationship between a and d is a > d.

8. The cutting tool according to claim 7, wherein, In the first unit layer and the third unit layer adjacent to the first unit layer, the ratio of the thickness λ1 of the first unit layer to the thickness λ3 of the third unit layer, λ1 / λ3, is 1.0 or more and 5.0 or less.

9. The cutting tool according to claim 7 or 8, wherein, M is silicon.

10. The cutting tool according to claim 7 or 8, wherein, M is boron.

11. The cutting tool according to any one of claims 7 to 10, 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.

12. The cutting tool according to any one of claims 7 to 11, wherein, The coating further includes a second layer disposed between the substrate and the first A layer. The composition of the second layer is the same as that of the first unit layer or the third unit layer.

13. The cutting tool according to claim 12, wherein, The composition of the second layer is the same as that of the first unit layer. The second layer is thicker than the first unit layer.

14. The cutting tool according to claim 12, wherein, The composition of the second layer is the same as that of the third unit layer. The second layer is thicker than the third unit layer.

15. The cutting tool according to any one of claims 7 to 14, wherein, The coating further includes a third layer disposed on the side of the first A layer opposite to the substrate. The third layer is composed of AlCrCeCN.

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