Cutting tool

Abstract

A cutting tool provided with a substrate and a coating that is disposed upon the substrate, wherein the coating includes a first layer, the first layer is formed from alternating layers consisting of first unit layers and second unit layers stacked in an alternating manner, each first unit layer is composed of Ti1-aMoaN, a is 0.01 to 0.20 inclusive, each second unit layer is composed of AlbV1-bN, and b is 0.40 to 0.80 inclusive.

Description

cutting tools

[0001] The present disclosure relates to cutting tools.

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

[0003] Special Publication No. 2022-512808

[0004] The cutting tool of the present disclosure is a cutting tool including a substrate and a coating disposed on the substrate, wherein the coating includes a first layer, the first layer being composed of alternating layers in which first unit layers and second unit layers are alternately stacked, and the first unit layer is composed of Ti １－ａ Mo ａ N, the a is 0.01 or more and 0.20 or less, and the second unit layer is Al ｂ V １－ｂ N, and the b is 0.40 or more and 0.80 or less.

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

[0006] [Problem to be solved by this disclosure] In recent years, efforts towards carbon neutrality have been accelerating both domestically and internationally against the backdrop of rapid global warming. In Japan, in order to achieve carbon neutrality by 2050, the manufacturing industry, especially the metal processing industry, is focusing on CO2 reduction from the perspective of environmental performance in addition to the conventional quality, processing efficiency, and cost. ２ There is a demand to reduce emissions.

[0007] In the metal cutting process, the majority of power is consumed by operational preparations, such as the circulation and supply of coolant (cutting fluid), which are primarily performed by hydraulic and pneumatic units and auxiliary equipment, rather than by the rotation of the machine's main shaft or feed drive during the process. Therefore, energy-saving efforts include improving the efficiency of motors and auxiliary equipment, as well as adopting inverter-controlled hydraulic units and optimizing the operation of hydraulic and pneumatic units and chip conveyors (chip transport). Furthermore, coolant-less technology (dry cutting) and semi-dry technology that atomizes coolant have been attracting attention in recent years. These technologies can reduce waste by reducing the amount of coolant used, and also conserve the power required to use the coolant. Therefore, advances in these energy-saving technologies are anticipated.

[0008] Conventionally, research has been conducted into dry machining to find the optimum conditions for applying various cutting tools and for individual workpiece materials, and dry machining is sometimes performed on non-ferrous metals, cast iron, etc. On the other hand, although there is a high demand for dry machining on workpiece materials that are considered difficult to cut, such as general steel and super heat-resistant alloys, dry machining is difficult even at present, and new tool materials that can be used in these situations are being actively developed.

[0009] As a coating material for tool, a nitride film containing aluminum (Al) and vanadium (V) as its main components has been proposed (Patent Document 1). ２The cutting edge temperature of cutting tools during cutting tends to be high due to factors such as the demand for dry machining without cutting fluids from the perspective of reducing energy consumption and protecting the global environment, the increasing need for higher cutting speeds to improve machining efficiency, and the diversification of workpiece materials, particularly in the aircraft and medical fields, where cutting of heat-resistant alloys and titanium alloys, which are considered difficult to cut, is on the rise. High cutting edge temperatures drastically shorten the life of cutting tools. Therefore, there is a demand for cutting tools that can maintain excellent tool life even under such harsh cutting conditions.

[0010] Effect of the Present Disclosure According to the present disclosure, it is possible to provide a cutting tool that has a long tool life, especially in cutting operations that are performed under conditions where the cutting edge temperature is high.

[0011] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. (1) A cutting tool of the present disclosure is a cutting tool including a substrate and a coating disposed on the substrate, wherein the coating includes a first layer, the first layer being composed of alternating layers in which first unit layers and second unit layers are alternately stacked, and the first unit layer is composed of Ti １－ａ Mo ａ N, the a is 0.01 or more and 0.20 or less, and the second unit layer is Al ｂ V １－ｂ N, and the b is 0.40 or more and 0.80 or less.

[0012] According to the present disclosure, it is possible to provide a cutting tool that has a long tool life, especially in cutting operations that are performed under conditions where the cutting edge temperature is high.

[0013] (2) In the above (1), the ratio λ2 / λ1 of the thickness λ2 μm of the second unit layer to the thickness λ1 μm of the first unit layer may be 1.0 or more and 5.0 or less, in the first unit layer and the second unit layer adjacent to the first unit layer. This allows the cutting tool to have a longer tool life.

[0014] (3) In the above (1) or (2), the average thickness of the first unit layer may be 0.002 μm or more and 0.2 μm or less, and the average thickness of the second unit layer may be 0.002 μm or more and 0.2 μm or less. This allows the cutting tool to have a longer tool life.

[0015] (4) In any one of the above (1) to (3), the coating may further include a surface layer provided on the side of the first layer opposite to the substrate, and the surface layer may be made of TiMoON or AlVON. This allows the cutting tool to have a longer tool life.

[0016] (5) A cutting tool according to the present disclosure is a cutting tool including a substrate and a coating disposed on the substrate, wherein the coating includes a second layer, the second layer being composed of alternating layers in which first unit layers and third unit layers are alternately stacked, and the first unit layer is composed of Ti １－ａ Mo ａ N, the a is 0.01 or more and 0.20 or less, and the third unit layer is Al ｃ V １－ｃ－ｄ X ｄ N, wherein X is one or two elements selected from the group consisting of boron, silicon, scandium, yttrium, and cerium, c is 0.40 or more and 0.80 or less, and d is 0.001 or more and 0.05 or less.

[0017] According to the present disclosure, it is possible to provide a cutting tool that has a long tool life, especially in cutting operations that are performed under conditions where the cutting edge temperature is high.

[0018] (6) In the above (5), the ratio λ3 / λ1 of the thickness λ3 μm of the third unit layer to the thickness λ1 μm of the first unit layer may be 1.0 or more and 5.0 or less, in the first unit layer and the third unit layer adjacent to the first unit layer. This allows the cutting tool to have a longer tool life.

[0019] (7) In the above (5) or (6), the average thickness of the first unit layer may be 0.002 μm or more and 0.2 μm or less, and the average thickness of the third unit layer may be 0.002 μm or more and 0.2 μm or less. This allows the cutting tool to have a longer tool life.

[0020] (8) In any one of the above (5) to (7), the coating further includes a surface layer provided on the side of the second layer opposite to the substrate, the surface layer being made of TiMoON or AlVXON, and the X may be one or two elements selected from the group consisting of boron, silicon, scandium, yttrium, and cerium, thereby enabling the cutting tool to have a longer tool life.

[0021] [Details of the Embodiments of the Present Disclosure] Specific examples of cutting tools according to the present disclosure will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0022] In the present disclosure, the notation in the form of "A to B" means A or more and B or less, and when no unit is specified for A and a unit is specified only for B, the unit of A and the unit of B are the same.

[0023] In the present disclosure, when a compound or the like is represented by a chemical formula, unless the atomic ratio is particularly limited, it is intended to include any conventionally known atomic ratio, and should not necessarily be limited to only those within the stoichiometric range.

[0024] In the present disclosure, when one or more numerical values ​​are listed as the lower limit and the upper limit of a numerical range, the combination of any one numerical value listed as the lower limit and any one numerical value listed as the upper limit is also considered to be disclosed.

[0025] [Embodiment 1: Cutting Tool (1)] A cutting tool according to one embodiment of the present disclosure will be described with reference to Figures 1 to 5. A cutting tool 1 according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 1") is a cutting tool 1 including a substrate 2 and a coating 3 disposed on the substrate 2, wherein the coating 3 includes a first layer 13, the first layer 13 being composed of alternating layers in which first unit layers 12 and second unit layers 15 are alternately stacked, and the first unit layer 12 is composed of Ti １－ａ Mo ａ N, a is 0.01 or more and 0.20 or less, and the second unit layer 15 is Al ｂ V １－ｂ N, and b is 0.40 or more and 0.80 or less.

[0026] The cutting tool of the first embodiment can have a long tool life, especially in cutting operations performed under conditions where the cutting edge temperature is high. The reason for this is presumed to be as follows.

[0027] The first unit layer is Ti １－ａ Mo ａ The first unit layer contains Mo (molybdenum), and is oxidized during cutting to form MoO ３ This MoO ３ Since the melting point of the first unit layer is 795°C, it softens at the temperature during cutting, functions as a lubricant, and can reduce the coefficient of friction on the rake face of the tool. As a result, the first layer including the first unit layer can improve adhesion resistance, sliding properties, and wear resistance in processes where the cutting edge becomes hot, such as dry cutting processes.

[0028] The second unit layer is Al ｂ V １－ｂ The second unit layer contains Al. Since Al is easily oxidized, the coating containing the second unit layer has Al on the surface side of the first layer. ２ O ３ As a result, the heat insulating property and oxidation resistance of the first layer can be improved.

[0029] The second unit layer is oxidized during cutting and is formed of V, an oxide of V. ２ O ５ is generated.２ O ５ Since the melting point of SiO2 is 690°C, it softens at the temperature during cutting, functions as a lubricant, and can reduce the coefficient of friction on the rake face of the tool.

[0030] The first layer is composed of alternating layers in which first unit layers and second unit layers are alternately stacked. The composition and crystal lattice are discontinuous at the interface between the first unit layer and the second unit layer. Therefore, if a crack occurs on the surface of the coating during cutting, the propagation of the crack can be suppressed at the interface. A coating including the first layer suppresses chipping and fracture.

[0031] As described above, a cutting tool including a first layer made up of alternating layers in which first unit layers and second unit layers are alternately stacked has an improved tool life.

[0032] 1 and 2, 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 at least a portion of the substrate 2 that is involved in cutting. The coating 3 may also cover the entire surface of the substrate 2. Partially different configurations of the coating 3 do not depart from the scope of this embodiment. In this disclosure, the portion of the substrate 2 that is involved in cutting refers to a region on the surface of the substrate 2 that is at least within 50 μm, 100 μm, or 300 μm away from the cutting edge.

[0033] The cutting tool of embodiment 1 can be suitably used as a cutting tool such as a drill, an end mill, an indexable cutting tip for a drill, an indexable cutting tip for an end mill, an indexable cutting tip for a milling process, an indexable cutting tip for a turning process, a metal saw, a gear cutting tool, a reamer, and a tap.

[0034] <Substrate> Any conventionally known material can be used as the substrate.For example, the substrate can be made of cemented carbide (WC-based cemented carbide, cemented carbide containing WC and Co, cemented carbide made by adding carbonitrides of Ti, Ta, Nb, etc. to WC and Co, etc.), cermet (mainly composed of TiC, TiN, TiCN, etc.), high-speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cubic boron nitride sintered body, or diamond sintered body.

[0035] The substrate may be, in particular, a WC-based cemented carbide or cermet (particularly a TiCN-based cermet). WC-based cemented carbide or cermet has an excellent balance between hardness and strength, particularly at high temperatures, and therefore, when used as a substrate for a cutting tool, can contribute to extending the life of the cutting tool.

[0036] <Coating> In the cutting tool of embodiment 1, the coating includes a first layer. By covering the substrate, the coating has the effect of improving various properties of the cutting tool, such as wear resistance and chipping resistance, and thereby extending the life of the cutting tool.

[0037] The coating may include other layers in addition to the first layer, such as a base layer 16 disposed between the substrate 2 and the first layer 13, and a surface layer 14 provided on the side of the first layer 13 opposite the substrate 2, as shown in Figures 3 and 4 .

[0038] The coating may have a total thickness of 0.4 μm or more and 15 μm or less. When the total thickness of the coating is 0.4 μm or more, the effect of extending the life of the cutting tool by providing the coating is easily achieved. On the other hand, when the total thickness of the coating is 15 μm or less, chipping of the coating is less likely to occur in the early stages of cutting, and the life of the cutting tool can be extended.

[0039] The total thickness of the coating can be measured by observing the cross section of the coating using a scanning electron microscope (SEM). The cutting tool is cut in a direction normal to the surface of the coating to prepare a cross section sample. The cross section sample is observed with the SEM. The observation magnification is 5000 to 10000 times, and the measurement field of view is 100 to 500 μm. ２The thickness width of the coating is measured at three points in one field of view, and the average value of the thickness widths at the three points is calculated. This average value corresponds to the overall thickness of the coating. The thickness of each layer described below is also measured in the same manner unless otherwise specified.

[0040] The compressive residual stress of the coating may have an absolute value of 6 GPa or less. The compressive residual stress of the coating is a type of internal stress (intrinsic strain) present throughout the coating, and is a stress expressed as a "-" (negative) numerical value (unit: "GPa" is used in this embodiment). Therefore, the concept of a large compressive residual stress refers to a large absolute value of the numerical value, and the concept of a small compressive residual stress refers to a small absolute value of the numerical value. In other words, an absolute value of the compressive residual stress of 6 GPa or less means that the compressive residual stress of the coating 3 is between -6 GPa and 0 GPa.

[0041] When the compressive residual stress of the coating is 0 GPa or less, the propagation of cracks generated from the outermost surface of the coating is easily suppressed.On the other hand, when the absolute value of the compressive residual stress is 6 GPa or less, the magnitude of the stress is appropriate, and peeling of the coating from the edge of the cutting tool before cutting begins is easily suppressed.

[0042] The compressive residual stress of the coating was measured using an X-ray residual stress analyzer. ２ It is measured by the ψ method (see pages 54-66 of "X-Ray Stress Measurement Method" (Japan Society of Materials Science, published by Yokendo Co., Ltd. in 1981)).

[0043] The coating hardness is highly effective when it is 30 GPa or more and 55 GPa or less, and may be 35 GPa or more and 50 GPa or less. This means that the coating has sufficient hardness. The hardness of the entire coating is measured by a nanoindenter method (Nano Indenter XP manufactured by MTS). Specifically, this is performed according to ISO 14577, with a measurement load of 10 mN (1 gf), and the hardness is measured at three locations on the surface of the coating 3, and the average value of the hardness values ​​at the three locations is calculated. This average value corresponds to the hardness of the coating 3.

[0044] <First Layer> In the cutting tool of Embodiment 1, the first layer is composed of alternating layers in which first unit layers and second unit layers are alternately stacked. The fact that the first layer is composed of alternating layers in which first unit layers and second unit layers are alternately stacked can be confirmed by observing a thin section sample including a cross section of the coating with a TEM (transmission electron microscope) and observing the difference in contrast.

[0045] Either the first unit layer or the second unit layer may be disposed closest to the substrate side. In Fig. 1 , the first unit layer 12 is disposed directly on the substrate 2. In Fig. 2 , the second unit layer 15 is disposed directly on the substrate 2. Either the first unit layer 12 or the second unit layer 15 may be disposed on the surface side of the coating 3. In Fig. 1 , the second unit layer 15 is disposed on the surface side of the coating 3. In Fig. 2 , the first unit layer 12 is disposed on the surface side of the coating 3.

[0046] The thickness of the first layer 13 may be 0.5 μm or more and 15 μm or less, 2 μm or more and 15 μm or less, or 5 μm or more and 10 μm or less. When the thickness of the first layer 13 is 0.5 μm or more, excellent wear resistance can be exhibited in continuous cutting. When the thickness of the first layer 13 is 15 μm or less, excellent chipping resistance can be exhibited in interrupted cutting.

[0047] The thickness of the first layer can be measured by observing the cross section of the coating using a transmission electron microscope (TEM). The cutting tool is cut in a direction normal to the surface of the coating to prepare a thin section sample including the cross section. The thin section sample is observed with the TEM. The observation magnification is set to 20,000 to 5,000,000 times, and the measurement field of view is set to 0.0016 to 80 μm. ２ The thickness width of the first layer is measured at three points in one field of view, and the average value of the thickness widths at the three points is calculated. This average value corresponds to the thickness of the first layer.

[0048] The first unit layer may have a cubic crystal structure. When the first unit layer has a cubic crystal structure, the abrasion resistance of the coating is improved. The second unit layer may include a cubic crystal structure. When the second unit layer has a cubic crystal structure, the hardness of the coating is improved. The crystal structure of each layer in the coating can be analyzed using an X-ray diffraction device known in the art.

[0049] An example of an apparatus used for X-ray diffraction measurement is the "SmartLab" (trade name) manufactured by Rigaku Corporation. The conditions for X-ray diffraction measurement are as follows: (XRD measurement conditions) Scanning axis: 2θ-θ X-ray source: Cu-Kα ray (1.541862 Å) Detector: 0-dimensional detector (scintillation counter) Tube voltage: 45 kV Tube current: 40 mA Incident optical system: Use of a mirror Receiving optical system: Use of an analyzer crystal (PW3098 / 27) Step: 0.03° Integration time: 2 seconds Scan range (2θ): 10° to 120°

[0050] <Composition of First Unit Layer and Composition of Second Unit Layer> The first unit layer is composed of Ti １－ａ Mo ａ N, and a is 0.01 or more and 0.20 or less. a may be 0.03 or more and 0.18 or less, 0.05 or more and 0.15 or less, or 0.08 or more and 0.14 or less.

[0051] In the present disclosure, "the first unit layer is Ti １－ａ Mo ａ The term "comprised of N" means that the first unit layer is made of Ti, as long as the effect of the present disclosure is not impaired. １－ａ Mo ａ This means that the first unit layer may contain unavoidable impurities in addition to N. Examples of the unavoidable impurities include oxygen and carbon. The total content of the unavoidable impurities in the first unit layer may be greater than 0 atomic % and less than 1 atomic %.

[0052] The second unit layer is Al ｂ V １－ｂ N, and b is 0.40 or more and 0.80 or less. b may be 0.45 or more and 0.75 or less, 0.50 or more and 0.70 or less, or 0.55 or more and 0.65 or less.

[0053] In the present disclosure, "the second unit layer is Al ｂ V １－ｂ The phrase "made of AlN" means that the second unit layer 15 is made of AlN as long as it does not impair the effect of the present disclosure.ｂ V １－ｂ This means that the second unit layer may contain unavoidable impurities in addition to N. Examples of the unavoidable impurities include oxygen and carbon. The total content of the unavoidable impurities in the second unit layer may be more than 0 atomic % and less than 1 atomic %.

[0054] The above a, b, and the content of inevitable impurities in the first unit layer and the content of inevitable impurities in the second unit layer are measured by elemental analysis of a cross section of the coating using a transmission electron microscope (TEM). A cutting tool is cut in a direction normal to the surface of the coating to prepare a thin section sample including a cross section of the coating. An EDS (Energy DispersiCre X-ray Spectroscopy) attached to the TEM is used to irradiate the thin section sample with an electron beam, and the energy and number of characteristic X-rays generated are measured to perform elemental analysis of the first unit layer and the second unit layer. Five layers each of the first unit layer and the second unit layer are arbitrarily selected and subjected to elemental analysis. The average composition of the five first unit layers is determined. This average composition corresponds to the composition of the first unit layer. The average composition of the five second unit layers is determined. This average composition corresponds to the composition of the second unit layer. When the number of layers of each of the first unit layer and the second unit layer is four or less, elemental analysis is performed on all layers to determine the average composition of the first unit layer and the second unit layer. As long as the measurement is performed using the same cutting tool, it has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0055] In the present disclosure, the composition of the first unit layer is Ti １－ａ Mo ａ In N, the total number of Ti and Mo atoms A Ｍ１ Number of N atoms A Ｎ１ Ratio A Ｎ１ / A Ｍ１ In the present disclosure, the composition Al of the second unit layer is 0.8 or more and 1.2 or less. ｂ V １－ｂ In N, the total number of Al and V atoms, A Ｍ２ Number of N atoms A Ｎ２ Ratio A Ｎ２ / A Ｍ２ is 0.8 or more and 1.2 or less. Ｎ１ / A Ｍ１ and ratio AＮ２ / A Ｍ２ can be measured by Rutherford backscattering (RBS) method. Ｎ１ / A Ｍ１ and ratio A Ｎ２ / A Ｍ２ It has been confirmed that the effects of the present disclosure are not impaired if the value is within the above range.

[0056] <Average Thickness of First Unit Layer and Average Thickness of Second Unit Layer> The average thickness of the first unit layer may be 0.002 μm or more and 0.2 μm or less, and the average thickness of the second unit layer may be 0.002 μm or more and 0.2 μm or less. This can further suppress the progression of cracks that occur on the surface of the coating. The average thickness of the first unit layer may be 0.005 μm or more and 0.15 μm or less, or 0.01 μm or more and 0.1 μm or less. The average thickness of the second unit layer may be 0.005 μm or more and 0.15 μm or less, or 0.01 μm or more and 0.10 μm or less.

[0057] The average thickness of the first unit layer and the average thickness of the second unit layer are measured by the same method as the method for measuring the thickness of the first layer.

[0058] As shown in FIG. 5 , the ratio λ2 / λ1 of the thickness λ2 μm of the second unit layer 15 to the thickness λ1 μm of the first unit layer 12 between the first unit layer 12 and the second unit layer 15 adjacent to the first unit layer 12 may be 1.0 or greater and 5.0 or less. The second unit layer has high oxidation resistance and low thermal conductivity, making it difficult for heat generated during cutting to be transmitted to the substrate. When the ratio λ2 / λ1 is 1.0 or greater, the proportion of the second unit layer in the coating increases relatively, and the Al content in the coating increases, improving the heat barrier properties of the cutting tool as a whole, particularly its wear resistance during continuous cutting. When the ratio λ2 / λ1 is 1.0 or greater, the toughness of the coating tends to improve. On the other hand, when the ratio λ2 / λ1 is 5.0 or less, the stacking of the first unit layer 12 and the second unit layer 15 tends to more easily suppress crack propagation.

[0059] λ2 / λ1 may be 1.1 or more and 5.0 or less, 1.2 or more and 5.0 or less, 1.3 or more and 4.0 or less, 1.8 or more and 3.0 or less, or 2.0 or more and 2.5 or less.

[0060] In Figure 5, for the purpose of explanation, the thicknesses of all three first unit layers 12 are shown as λ1 and the thicknesses of all three second unit layers 15 are shown as λ2. However, as long as the above-mentioned λ2 / λ1 relationship is satisfied between adjacent first unit layers and second unit layers, the thicknesses λ1 of the three first unit layers 12 do not need to be the same, and the thicknesses λ2 of the three second unit layers 15 do not need to be the same.

[0061] In the first layer, the number of stacked first unit layers and second unit layers may be 5 or more and 500 or less, 10 or more and 500 or less, 100 or more and 400 or less, or 200 or more and 350 or less. By stacking the first unit layers and the second unit layers, it is possible to sufficiently obtain the effect of improving hardness and compressive residual stress in a well-balanced manner.

[0062] In the first layer, the number of first unit layers and second unit layers can be determined by observing a thin section sample of the cross section of the coating using a TEM (transmission electron microscope) at a magnification of 20,000 to 5,000,000 times.

[0063] 3 and 4, the coating 3 may further include an underlayer 16 disposed between the substrate 2 and the first layer 13. The composition of the underlayer 16 may be the same as the composition of the first unit layer 12 or the composition of the second unit layer 15. This can improve the adhesion between the substrate 2 and the coating 3.

[0064] When the composition of the underlayer is the same as that of the first unit layer, even if the underlayer is exposed at the beginning of cutting, the underlayer has good sliding properties, and therefore wear resistance can be improved.

[0065] When the composition of the underlayer is the same as that of the first unit layer, the thickness of the underlayer may be greater than that of the first unit layer. This can further improve adhesion between the substrate and the coating. The thickness of the underlayer may be more than 1.0 times and not more than 500 times, 2.0 times or more and not more than 500 times, 4.0 times or more and not more than 120 times, or 10.0 times or more and not more than 50 times the thickness of the first unit layer.

[0066] When the composition of the underlayer is the same as that of the first unit layer, the thickness of the underlayer may be 0.1 μm or more and 2 μm or less, 0.3 μm or more and 2 μm or less, or 0.4 μm or more and 2 μm or less. If the thickness of the underlayer is less than 0.1 μm, it tends to be difficult to obtain the effect of improving wear resistance by making the underlayer have the same composition as the first unit layer. If the thickness of the underlayer exceeds 2 μm, the crystal grains will become thicker and grain boundaries will occur, so it tends to be difficult to obtain the effect of improving wear resistance.

[0067] When the composition of the underlayer is the same as the composition of the first unit layer, the first unit layer 12 may be laminated directly on the underlayer 16, as shown in Fig. 3. Alternatively, the second unit layer 15 may be laminated directly on the underlayer 16, as shown in Fig. 4. When the composition of the underlayer 16 is the same as the composition of the first unit layer 12 and the first unit layer 12 is laminated directly on the underlayer 16, the underlayer 16 and the first unit layer 12 have a continuous crystal structure.

[0068] When the composition of the base layer is the same as the composition of the second unit layer, even if the base layer is exposed at the beginning of cutting, oxidation from the interface between the substrate and the coating can be suppressed and cutting heat can be insulated.

[0069] When the composition of the underlayer is the same as that of the second unit layer, the thickness of the underlayer may be greater than that of the second unit layer. This can further improve adhesion between the substrate and the coating. The thickness of the underlayer may be more than 1.0 times and less than 500 times, 2.0 times or more and less than 500 times, 4.0 times or more and less than 120 times, or 10.0 times or more and less than 50 times the thickness of the second unit layer.

[0070] When the composition of the underlayer is the same as that of the second unit layer, the thickness of the underlayer may be 0.1 μm or more and 2 μm or less, 0.3 μm or more and 2 μm or less, or 0.4 μm or more and 2 μm or less.

[0071] When the composition of the underlayer is the same as the composition of the second unit layer, the first unit layer 12 may be laminated directly on the underlayer 16, as shown in Fig. 3. Alternatively, the second unit layer 15 may be laminated directly on the underlayer 16, as shown in Fig. 4. When the composition of the underlayer 16 is the same as the composition of the second unit layer 15 and the second unit layer 15 is laminated directly on the underlayer 16, the underlayer 16 and the second unit layer 15 have a continuous crystal structure.

[0072] 1 to 4, the coating 3 may further include a surface layer 14 provided on the side of the first layer 13 opposite the substrate 2. The surface layer 14 may be made of TiMoON or AlVON. This reduces the coefficient of friction of the coating and extends the life of the cutting tool.

[0073] In general, oxynitrides tend to have higher adhesion resistance to workpiece materials than nitrides. The improved adhesion resistance is thought to be due to the contribution of oxygen atoms. When a coating includes a surface layer made of oxynitride, the coating's adhesion resistance to the workpiece material is improved, resulting in a longer cutting tool life.

[0074] It is possible to impart a predetermined color to the surface layer by adjusting the composition ratio of O and N. This makes it possible to impart design and distinctiveness to the appearance of the cutting tool, making it commercially useful.

[0075] The thickness of the surface layer 14 may be 0.1 μm or more and 2 μm or less. When the thickness of the surface layer 14 is 0.1 μm or more, the lubricity-imparting effect of the surface layer 14 is easily obtained. When the thickness of the surface layer exceeds 2 μm, the lubricity-imparting effect described above tends not to be further improved. Therefore, in consideration of cost, the thickness of the surface layer may be 2 μm or less.

[0076] <Intermediate Layer> In the cutting tool of the first embodiment, the coating may include an intermediate layer disposed between the base layer and the first layer. Examples of intermediate layers include TiMoN, AlVCeN, AlVN, AlVBN, AlVSiN, AlVYN, and AlVScN. The thickness of the intermediate layer may be 0.1 μm or more and 2 μm or less, 0.3 μm or more and 1.5 μm or less, or 0.4 μm or more and 1.0 μm or less.

[0077] [Embodiment 2: Cutting Tool (2)] A cutting tool according to another embodiment of the present disclosure will be described with reference to Figures 6 to 10. A cutting tool 1 according to another embodiment of the present disclosure (hereinafter also referred to as "Embodiment 2") is a cutting tool 1 including a substrate 2 and a coating 3 disposed on the substrate 2, wherein the coating 3 includes a second layer 13A, the second layer 13A being composed of alternating layers in which first unit layers 12 and third unit layers 17 are alternately stacked, and the first unit layers 12 are composed of Ti １－ａ Mo ａ N, a is 0.01 or more and 0.20 or less, and the third unit layer 17 is Al ｃ V １－ｃ－ｄ X ｄ N; X is one or two elements selected from the group consisting of boron, silicon, scandium, yttrium, and cerium; c is 0.40 or more and 0.80 or less; and d is 0.001 or more and 0.05 or less.

[0078] The cutting tool of the second embodiment can have a long tool life, especially in cutting operations performed under conditions where the cutting edge temperature is high. The reason for this is presumed to be as follows.

[0079] The first unit layer is Ti １－ａ Mo ａ N. Therefore, for the same reasons as those described in the first embodiment, the first layer including the first unit layer can improve adhesion resistance, sliding properties, and wear resistance in processing in which the cutting edge becomes hot, such as during dry cutting processing.

[0080] The third unit layer is Al ｃ V １－ｃ－ｄ X ｄ The third unit layer contains Al. Since Al is easily oxidized, the coating containing the third unit layer has Al on the surface side of the second layer. ２ O ３ As a result, the heat insulating property and oxidation resistance of the second layer can be improved.

[0081] The third unit layer is oxidized during cutting and is formed of V oxide, V. ２ O ５ is generated.２ O ５ Since the melting point of SiO2 is 690°C, it softens at the temperature during cutting, functions as a lubricant, and can reduce the coefficient of friction on the rake face of the tool.

[0082] The second layer is composed of alternating layers in which first unit layers and third unit layers are alternately stacked. The composition and crystal lattice are discontinuous at the interface between the first unit layer and the third unit layer. Therefore, if a crack occurs on the surface of the coating during cutting, the propagation of the crack can be suppressed at the interface. Coatings including the second layer suppress chipping and fracture.

[0083] The cutting tool of the second embodiment can have basically the same configuration as the cutting tool of the first embodiment, except for the configurations of the second layer, the base layer, and the surface layer. The "second layer," "base layer," and "surface layer" will be described below.

[0084] <Second Layer> In the cutting tool of embodiment 2, the second layer is composed of alternating layers in which first unit layers and third unit layers are alternately stacked. The fact that the second layer is composed of alternating layers in which first unit layers and third unit layers are alternately stacked can be confirmed by observing the cross section of the coating with a TEM and observing the difference in contrast. The thickness of the second layer can be the same as the thickness of the first layer described in embodiment 1. Either the first unit layer or the third unit layer may be disposed closest to the substrate side. The first unit layer can have a cubic crystal structure. The third unit layer can include a cubic crystal structure.

[0085] <Composition of First Unit Layer and Composition of Third Unit Layer> Composition of the first unit layer in embodiment 2: Ti １－ａ Mo ａ N is the composition of the first unit layer of embodiment 1. １－ａ Mo ａ It can be the same as N.

[0086] The third unit layer is Al ｃ V １－ｃ－ｄ X ｄN, X is one or two elements selected from the group consisting of boron, silicon, scandium, yttrium, and cerium, c is 0.40 or more and 0.80 or less, and d is 0.001 or more and 0.05 or less. The third unit layer 17 can have both excellent hardness and excellent oxidation resistance. The reason for this is presumed to be as follows.

[0087] Third unit layer Al ｃ V １－ｃ－ｄ X ｄ In the case where X is boron in N, the boron increases the hardness of the third unit layer, thereby increasing the hardness of the entire coating. Furthermore, boron oxides formed by oxidation of the surface of the cutting tool during cutting densify the aluminum oxides in the third unit layer, improving the oxidation resistance of the third unit layer. Furthermore, boron oxides have a low melting point, so they act as a lubricant during cutting, preventing adhesion of the workpiece.

[0088] Third unit layer Al ｃ V １－ｃ－ｄ X ｄ In the case where X in N is silicon, the structure of the third unit layer becomes finer, thereby improving the hardness and oxidation resistance of the third unit layer and improving the hardness and oxidation resistance of the entire coating.

[0089] Third unit layer Al ｃ V １－ｃ－ｄ X ｄ In N, when X is one or two elements selected from the group consisting of scandium (Sc), yttrium (Y), and cerium (Ce), the elements precipitate at the grain boundaries of the third unit layer, and their oxides can suppress the inward diffusion of oxygen from the coating surface through the grain boundaries, thereby improving the oxidation resistance of the third unit layer and extending the life of a cutting tool including the third unit layer.

[0090] The above-mentioned c is 0.40 or more and 0.80 or less. This makes the crystal structure of the third unit layer a cubic system, increasing the hardness of the third unit layer and improving the wear resistance. c may be 0.45 or more and 0.75 or less, 0.50 or more and 0.70 or less, or 0.55 or more and 0.65 or less.

[0091] The above d is 0.001 or more and 0.05 or less. This can improve the hardness and oxidation resistance of the second layer. d may be 0.01 or more and 0.05 or less, 0.02 or more and 0.05 or less, 0.02 or more and 0.04 or less, or 0.02 or more and 0.03 or less.

[0092] In the present disclosure, "the third unit layer is Al ｃ V １－ｃ－ｄ X ｄ The term "consisting of AlN" means that the third unit layer is made of AlN as long as it does not impair the effect of the present disclosure. ｃ V １－ｃ－ｄ X ｄ This means that the third unit layer may contain unavoidable impurities in addition to N. Examples of the unavoidable impurities include oxygen and carbon. The total content of the unavoidable impurities in the third unit layer may be more than 0 atomic % and less than 1 atomic %.

[0093] The contents of the inevitable impurities in the above c, d, and the third unit layer are measured using a transmission electron microscope (TEM). The specific measurement method is the same as the measurement method in the above a described in embodiment 1. It has been confirmed that, as long as the measurement is performed using the same cutting tool, there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0094] In the present disclosure, the composition of the first unit layer is Ti １－ａ Mo ａ In N, the total number of Ti and Mo atoms A Ｍ１ Number of N atoms A Ｎ１ Ratio A Ｎ１ / A Ｍ１ In the present disclosure, the composition of the third unit layer, Al ｃ V １－ｃ－ｄ X ｄ In N, the total number of Al, V and X atoms is A Ｍ３ Number of N atoms A Ｎ３ Ratio A Ｎ３ / A Ｍ３ is 0.8 or more and 1.2 or less. Ｎ３ / A Ｍ３ can be measured by Rutherford backscattering (RBS) method. Ｎ１ / A Ｍ１ and ratio A Ｎ３ / AＭ３ It has been confirmed that the effects of the present disclosure are not impaired if the value is within the above range.

[0095] <Average Thickness of First Unit Layer and Average Thickness of Third Unit Layer> The average thickness of the first unit layer may be 0.002 μm or more and 0.2 μm or less, and the average thickness of the third unit layer may be 0.002 μm or more and 0.2 μm or less. This can further suppress the progression of cracks that occur on the surface of the coating. The average thickness of the first unit layer may be 0.005 μm or more and 0.15 μm or less, or 0.01 μm or more and 0.1 μm or less. The average thickness of the third unit layer may be 0.005 μm or more and 0.15 μm or less, or 0.01 μm or more and 0.10 μm or less.

[0096] The average thickness of the first unit layer and the average thickness of the third unit layer can be determined by the same method as the method for measuring the thickness of the first layer described in the first embodiment.

[0097] As shown in FIG. 10 , the ratio λ3 / λ1 of the thickness λ3 μm of the third unit layer 17 to the thickness λ1 μm of the first unit layer 12 between the first unit layer 12 and the third unit layer 17 adjacent to the first unit layer 12 may be 1.0 or greater and 5.0 or less. The third unit layer has high oxidation resistance and low thermal conductivity, making it difficult for heat generated during cutting to be transmitted to the substrate. When the ratio λ3 / λ1 is 1.0 or greater, the proportion of the third unit layer in the coating increases relatively, and the Al content in the coating increases, improving the overall heat barrier of the cutting tool, particularly its wear resistance during continuous cutting. When λ3 / λ1 is 1.0 or greater, the toughness of the coating tends to improve. On the other hand, when λ3 / λ1 is 5.0 or less, the stacking of the first unit layer and the third unit layer tends to more easily suppress crack propagation.

[0098] λ3 / λ1 may be 1.1 or more and 5.0 or less, 1.2 or more and 5.0 or less, 1.3 or more and 4.0 or less, 1.8 or more and 3.0 or less, or 2.0 or more and 2.5 or less.

[0099] In Figure 10, for the sake of explanation, the thicknesses of all three first unit layers 12 are shown as λ1 and the thicknesses of all three third unit layers 17 are shown as λ3, but as long as the above-mentioned λ3 / λ1 relationship is satisfied between adjacent first unit layers and third unit layers, the thicknesses λ1 of the three first unit layers 12 do not need to be the same, and the thicknesses λ3 of the three third unit layers 17 do not need to be the same.

[0100] In the second layer, the number of stacked first unit layers and third unit layers may be 4 or more and 800 or less, 10 or more and 500 or less, 100 or more and 400 or less, or 200 or more and 350 or less. By stacking the first unit layers and the third unit layers, it is possible to sufficiently obtain the effect of improving hardness and compressive residual stress in a well-balanced manner.

[0101] In the second layer, the number of stacked first unit layers and the number of stacked third unit layers can be determined by the same method as the method for measuring the number of stacked first unit layers and the number of stacked second unit layers described in the first embodiment.

[0102] 8 and 9 , the coating 3 further includes an underlayer 16 disposed between the substrate 2 and the second layer 13A, and the composition of the underlayer 16 may be the same as the composition of the first unit layer 12 or the composition of the third unit layer 17. This can improve the adhesion between the substrate 2 and the coating 3.

[0103] When the composition of the underlayer is the same as that of the first unit layer, the effect and thickness of the underlayer are as described in the first embodiment.

[0104] When the composition of the base layer 16 is the same as the composition of the third unit layer 17, the third unit layer tends to have low stress, which can improve the peeling resistance of the coating, particularly in intermittent machining such as milling and end milling, in which loads are repeatedly applied to the cutting edge.

[0105] When the composition of the underlayer is the same as that of the third unit layer, the thickness of the underlayer may be thicker than that of the third unit layer. This can further improve adhesion between the substrate and the coating. The thickness of the underlayer may be more than 1.0 times and not more than 500 times, 2.0 times or more and not more than 500 times, 4.0 times or more and not more than 120 times, or 10.0 times or more and not more than 50 times the thickness of the third unit layer.

[0106] When the composition of the underlayer is the same as that of the third unit layer, the thickness of the underlayer may be 0.1 μm or more and 2 μm or less, 0.3 μm or more and 2 μm or less, or 0.4 μm or more and 2 μm or less.

[0107] When the composition of the underlayer is the same as the composition of the third unit layer, the first unit layer may be stacked directly on the underlayer, as shown in Fig. 8. Furthermore, the third unit layer may be stacked directly on the underlayer, as shown in Fig. 9. When the composition of the underlayer is the same as the composition of the third unit layer and the third unit layer is stacked directly on the underlayer, the underlayer and the third unit layer have a continuous crystal structure.

[0108] <Surface Layer> As shown in Figures 6 to 9, the coating 3 may further include a surface layer 14 provided on the side of the second layer 13A opposite the substrate 2. The surface layer 14 may be made of TiMoON or AlVXON. Here, X may be one or two elements selected from the group consisting of boron, silicon, scandium, yttrium, and cerium. X may be the same element as the X used in the third unit layer. This reduces the friction coefficient of the coating and extends the life of the cutting tool.

[0109] It is possible to impart a predetermined color to the surface layer by adjusting the composition ratio of O and N. This makes it possible to impart design and distinctiveness to the appearance of the cutting tool, making it commercially useful.

[0110] The thickness of the surface layer 14 can be as described in the first embodiment.

[0111] [Embodiment 3: Method for Manufacturing Cutting Tool] In embodiment 3, a method for manufacturing the cutting tool of embodiment 1 or embodiment 2 will be described. The method for manufacturing the cutting tool of embodiment 3 includes a first step of preparing a substrate and a second step of forming a coating on the substrate. The second step includes a step of forming a first layer or a second layer. Details of each step will be described below.

[0112] <First Step> In the first step, a substrate is prepared. The substrate may be the substrate described in embodiment 1. Any conventionally known substrate may be prepared.

[0113] <Second Step> In the second step, a coating is formed on the substrate. The second step includes forming a first layer or a second layer.

[0114] In the step of forming the first layer, the first layer is formed by alternately stacking first unit layers and second unit layers using a physical vapor deposition (PVD) method. In the step of forming the second layer, the second layer is formed by alternately stacking first unit layers and third unit layers using a PVD method. In order to improve the abrasion resistance of a coating including the first layer or the second layer, it is effective to form a layer made of a highly crystalline compound. The inventors have found that by using physical vapor deposition as a method for forming the first layer and the second layer, a layer made of a highly crystalline compound can be formed, and the coating has excellent abrasion resistance.

[0115] As the PVD method, at least one selected from the group consisting of cathodic arc ion plating, balanced magnetron sputtering, unbalanced magnetron sputtering, and HiPIMS (High Power Impulse Magnetron Sputtering) can be used. The cathodic arc ion plating method, which has a high ionization rate of the raw material elements, may also be used. When the cathodic arc ion plating method is used, it is possible to perform a metal ion bombardment treatment on the surface of the substrate before forming the first layer or the second layer, thereby significantly improving the adhesion between the substrate and the coating including the first layer or the second layer.

[0116] The cathodic arc ion plating method can be carried out, for example, by placing a substrate in an apparatus and a target as a cathode, and then applying a high voltage to the target to generate an arc discharge, thereby ionizing and evaporating the atoms that make up the target, and depositing the material on the substrate.

[0117] The balanced magnetron sputtering method can be carried out, for example, by placing a substrate in an apparatus, placing a target on a magnetron electrode equipped with a magnet that forms a balanced magnetic field, applying high-frequency power between the magnetron electrode and the substrate to generate gas plasma, and causing gas ions generated by the generation of this gas plasma to collide with the target, thereby depositing atoms released from the target on the substrate.

[0118] The unbalanced magnetron sputtering method can be performed by unbalancing the magnetic field generated by the magnetron electrodes in the balanced magnetron sputtering method. Furthermore, the HiPIMS method can also be used, which allows the application of a high voltage and produces a dense film.

[0119] <Other Steps> In addition to the step of forming the first or second layer, the second step can include a surface treatment step of the coating, such as polishing with a brush or dry or wet shot blasting. The second step can also include a step of forming other layers, such as a base layer, a surface layer, and an intermediate layer. The other layers can be formed by a conventionally known chemical vapor deposition method or physical vapor deposition method. From the viewpoint that the other layers can be formed successively in the order of the first unit layer and the second or third unit layer in a single physical vapor deposition apparatus, it is preferable to form the other layers by physical vapor deposition.

[0120] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0121] Example 1 <Samples 1 to 19, Samples 101 to 105> <Preparation of Cutting Tool> FIG. 11 is a schematic cross-sectional view of a cathodic arc ion plating apparatus used in Example 1, and FIG. 12 is a schematic top view of the apparatus of FIG. 11.

[0122] 11 and 12, a cathode 106 for a first unit layer, a cathode 107 for a second unit layer, and a cathode 120 for a surface layer, which are alloy targets serving as metal raw materials for the coating, and a rotary substrate holder 104 for placing a substrate are installed in a chamber 101. The composition of the cathode 106 is adjusted to obtain the composition of the first unit layer shown in Table 1. The composition of the cathode 107 is adjusted to obtain the composition of the second unit layer shown in Table 1. The composition of the cathode 120 is adjusted to obtain the composition of the surface layer shown in Table 2.

[0123] An arc power supply 108 is attached to cathode 106, an arc power supply 109 is attached to cathode 107, and an arc power supply (not shown) is attached to cathode 120. A bias power supply 110 is attached to substrate holder 104. A gas inlet 105 for introducing gas 102 and a gas outlet 103 for adjusting the pressure inside chamber 101 are provided inside chamber 101, and gas 102 inside chamber 101 can be sucked out from gas outlet 103 by a vacuum pump.

[0124] The substrate holder 104 was fitted with a substrate made of cemented carbide of grade JIS K20, with a tip of JIS CNMG120408 shape and a tip of SEMT13T3AGSN manufactured by Sumitomo Electric Hardmetal Corporation.

[0125] Next, the pressure inside the chamber 101 was reduced by a vacuum pump, and the substrate was heated to 600° C. by a heater installed inside the apparatus while being rotated, until the pressure inside the chamber 101 reached 1.0×10 －４The chamber was evacuated to a vacuum of 2.0 Pa. Next, argon gas was introduced through the gas inlet to maintain the pressure inside the chamber 101 at 2.0 Pa, and the voltage of the bias power supply 110 was gradually increased to -1000 V, and the surface of the substrate was cleaned for 15 minutes. Thereafter, the argon gas was exhausted from the chamber 101 to clean the substrate (argon bombardment treatment). In this manner, the substrate for each sample cutting tool was prepared.

[0126] Next, with the substrate rotated at the center, nitrogen was introduced as a reactive gas, and an arc current of 150 A was supplied to each of cathodes 106 and 107 while maintaining the substrate temperature at 600°C, the reactive gas pressure at 3.3 Pa, and the voltage of bias power supply 110 at a predetermined constant value in the range of -50 V to -200 V. Metal ions were then generated from cathodes 106 and 107, and an underlayer having the composition shown in Table 2 and a first layer having the composition shown in Table 1 were formed on the substrate.

[0127] When an underlayer was formed, the first layer was formed by alternately stacking one first unit layer and one second unit layer on the underlayer, with the number of layers shown in Table 1. When an underlayer was not formed, the first layer was formed by alternately stacking one first unit layer and one second unit layer on the substrate, with the number of layers shown in Table 1. The thickness of the underlayer, and the thickness and number of the first unit layers and second unit layers in the first layer were adjusted by the rotation speed of the substrate. The current supplied to the evaporation source was stopped when the thicknesses of the underlayer and the first layer reached the thicknesses shown in Tables 1 and 2, respectively. A "-" in the "Underlayer" column in Table 2 indicates that no underlayer was present.

[0128] Next, nitrogen gas and oxygen gas were introduced into the chamber 101 as reactive gases, and an arc current of 120 A was supplied to the cathode 120 while maintaining the substrate temperature at 500°C, the reactive gas pressure at 2.0 Pa, and the voltage of the bias power supply 110 at -350 V. This generated metal ions from the cathode 120, forming a surface layer on the first layer. The current supplied to the evaporation source was stopped when the thickness of the surface layer reached the thickness shown in Table 2. The amounts of nitrogen gas and oxygen gas introduced were adjusted so as to obtain the surface layer composition shown in Table 2. Thus, cutting tools of each sample were produced. A "-" in the "Surface Layer" column in Table 2 indicates that no surface layer was present.

[0129]

[0130]

[0131] <Evaluation> <Measurement of Composition of First Unit Layer> For each sample cutting tool, the composition of the first unit layer was measured by the method described in embodiment 1. １－ａ Mo ａ The value of a at N was obtained. The results are shown in the "a" column of Table 1. In Table 1, "-" in the "a" column means that the first unit layer is not present.

[0132] <Measurement of Composition of Second Unit Layer> For each sample cutting tool, the composition of the second unit layer was measured by the method described in embodiment 1. ｂ V １－ｂ The value of b at N was obtained. The results are shown in the "b" column of Table 1.

[0133] <Measurement of composition of base layer and surface layer> The compositions of the base layer and surface layer of each sample cutting tool were determined by the method described in embodiment 1. The results are shown in the "Composition" column of "Base layer" and the "Composition" column of "Surface layer" in Table 2. A "-" in the "Composition" column of "Base layer" in Table 2 indicates that a base layer was not present, and a "-" in the "Composition" column of "Surface layer" indicates that a surface layer was not present.

[0134] <Measurement of Number of Layers> For each sample cutting tool, the number of layers of each of the first unit layers and the second unit layers was determined by the method described in embodiment 1. For example, a number of layers of 10 indicates that the alternating layers include 10 first unit layers and 10 second unit layers. The results obtained are shown in the "Number of Layers" column in Table 1.

[0135] <Measurement of Average Thickness of First Unit Layer, Average Thickness of Second Unit Layer, Thickness of First Layer, Thickness of Base Layer, and Thickness of Surface Layer> For each sample cutting tool, the average thickness of the first unit layer, the average thickness of the second unit layer, the thickness of the first layer, the thickness of the base layer, and the thickness of the surface layer were determined by the method described in embodiment 1. The results obtained are shown in the "Average Thickness [μm]" of "First Unit Layer," "Average Thickness [μm]" of "Second Unit Layer," and "Thickness [μm]" of "First Layer" columns in Table 1, and in the "Thickness [μm]" of "Base Layer" and "Thickness [μm]" of "Surface Layer" columns in Table 2. A "-" indicates that the corresponding layer does not exist.

[0136] <Measurement of λ2 / λ1> For each sample cutting tool, λ2 / λ1 was determined by the method described in embodiment 1. The results obtained are shown in the "λ2 / λ1" column of Table 1. Note that "-" in the "λ2 / λ1" column of Table 1 means that at least one of the first unit layer and the second unit layer is absent.

[0137] <Measurement of Crystal Structure of First Unit Layer> For each cutting tool of Samples 1 to 19, the crystal structures of the first unit layer and the second unit layer were confirmed by performing XRD measurement on the first unit layer. The specific method is as described in Embodiment 1. For Samples 1 to 19, it was confirmed that the first unit layer had a cubic crystal structure, and the second unit layer had a cubic crystal structure.

[0138] <Measurement of Coating Hardness> The coating hardness of Samples 1 to 19 was measured by the method described in Embodiment 1. The coating hardness of these samples was confirmed to be within the range of 30 GPa or more and 55 GPa or less.

[0139] <Measurement of compressive residual stress of coating> The compressive residual stress of the coating of Samples 1 to 19 was measured by the method described in Embodiment 1. It was confirmed that the absolute value of the compressive residual stress of the coating of these samples was 6 GPa or less.

[0140] <Cutting Test 1: Continuous Turning Test> A continuous turning test was performed on each sample CNMG120408-shaped cutting tool under the following cutting conditions, and the time until the flank wear of the cutting edge reached 0.2 mm was measured. The results are shown in the "Cutting Time [min]" column of "Cutting Test 1" in Table 2. A longer cutting time indicates a longer tool life. <Cutting Conditions> Workpiece material: Inconel 718 (HB400) Cutting speed: 90 m / min Feed rate: 0.2 mm / rev Depth of cut: 1.5 mm Coolant: Water-soluble Cutting performed under the above cutting conditions corresponds to cutting performed under conditions where the cutting edge temperature is high.

[0141] The cutting tools of Samples 1 to 19 correspond to Examples, and the cutting tools of Samples 101 to 105 correspond to Comparative Examples. It was confirmed that the cutting tools of Samples 1 to 19 have a longer tool life in cutting operations performed under conditions where the cutting edge temperature is high, compared to the cutting tools of Samples 101 to 105.

[0142] <Cutting Test 2: Milling Test> For each sample, the SEMT13T3AGSN-shaped cutting tool was surface milled under the following cutting conditions, aligning the centerline of a 150 mm wide plate with the center of a wider cutter (φ160 mm). The cutting length was measured until the flank wear of the cutting edge reached 0.2 mm. The results are shown in the "Cutting Length [km]" column of "Cutting Test 2" in Table 2. A longer cutting length indicates a longer tool life. <Cutting Conditions> Workpiece: SKD11 (HB = 235); Cutting Speed: 200 m / min; Feed Rate: 0.15 mm / tooth; Axial Depth of Cut: 1.5 mm; Radial Depth of Cut: 150 mm; Coolant: Dry. The cutting process performed under the above cutting conditions corresponds to cutting performed under conditions where the cutting edge temperature is high.

[0143] The cutting tools of Samples 1 to 19 correspond to Examples, and the cutting tools of Samples 101 to 105 correspond to Comparative Examples. It was confirmed that the cutting tools of Samples 1 to 19 have a longer tool life in cutting operations performed under conditions where the cutting edge temperature is high, compared to the cutting tools of Samples 101 to 105.

[0144] Example 2 Samples 51 to 85, Samples 151 to 176 Preparation of Cutting Tools Substrates for cutting tools of each sample were prepared using the same method as in Example 1. While rotating the substrate at its center, argon and nitrogen were introduced as reactive gases. The substrate temperature was maintained at 600°C, the reactive gas pressure was 2.0 Pa, and the voltage of the bias power supply 110 was maintained at a predetermined constant value in the range of −50 V to −200 V. An arc current of 100 A was supplied to each of cathodes 106 and 107, generating metal ions from cathodes 106 and 107. Underlayers and second layers having the compositions shown in Tables 3 to 6 were formed on the substrate. The composition of cathode 106 was adjusted to obtain the composition of the first unit layer shown in Tables 3 to 4. The composition of cathode 107 was adjusted to obtain the composition of the third unit layer shown in Tables 3 to 4. The composition of the cathode 120 was adjusted to obtain the surface layer compositions shown in Tables 5 and 6.

[0145] When an underlayer was formed, the second layer was formed by alternately stacking the first unit layer and the third unit layer one by one on the underlayer, in the number of layers shown in Tables 3 and 4. When an underlayer was not formed, the second layer was formed by alternately stacking the first unit layer and the third unit layer one by one on the substrate, in the number of layers shown in Tables 3 and 4. The thickness of the underlayer, and the thickness and number of the first unit layer and the third unit layer in the second layer were adjusted by the rotation speed of the substrate. The current supplied to the evaporation source was stopped when the thicknesses of the underlayer and the second layer reached the thicknesses shown in Tables 3 to 6. The "-" in the "Underlayer" column in Tables 5 and 6 indicates that no underlayer was present.

[0146] Next, nitrogen gas and oxygen gas were introduced into the chamber 101 as reactive gases. While maintaining the substrate temperature at 350°C, the reactive gas pressure at 2.0 Pa, and the bias power supply 110 at -350 V, an arc current of 100 A was supplied to the cathode 120 to generate metal ions and form a surface layer on the second layer. The current supplied to the evaporation source was stopped when the surface layer reached the thickness shown in Tables 5 and 6. The amounts of nitrogen gas and oxygen gas introduced were adjusted to obtain the surface layer compositions shown in Tables 5 and 6. Thus, cutting tools of each sample were fabricated. In Tables 5 and 6, a "-" in the "Surface Layer" column indicates that no surface layer was present.

[0147]

[0148]

[0149]

[0150]

[0151] <Evaluation> For the cutting tools of each sample, the composition of the first unit layer, the composition of the third unit layer, the composition of the base layer, the composition of the surface layer, the number of layers of each of the first unit layer and the third unit layer, the average thickness of the first unit layer, the average thickness of the third unit layer, the thickness of the second layer, the thickness of the base layer, the thickness of the surface layer, λ3 / λ1 and the crystal structure of the first unit layer, the hardness of the coating, and the compressive residual stress of the coating were measured. The measurement methods for each item were as described in Example 1. The results are shown in Tables 3 to 6.

[0152] In Samples 51 to 85, it was confirmed that the first unit layer had a cubic crystal structure, and the second unit layer had a cubic crystal structure. It was confirmed that the hardness of the coatings of Samples 51 to 85 was within a range of 30 GPa or more and 55 GPa or less. It was confirmed that the absolute value of the compressive residual stress of the coatings of Samples 51 to 85 was 6 GPa or less.

[0153] <Cutting Test 3: Continuous Turning Test> A continuous turning test was performed on each sample CNMG120408-shaped cutting tool under the following cutting conditions, and the time until the flank wear of the cutting edge reached 0.2 mm was measured. The results are shown in the "Cutting Time [min]" column of "Cutting Test 3" in Tables 5 and 6. Note that in Tables 5 and 6, a longer cutting time indicates a longer tool life. (Cutting Conditions) Workpiece material: SCM440 (HB320) Cutting speed: 360 m / min Feed rate: 0.35 mm / rev Depth of cut: 2.0 mm Coolant: Water-soluble Cutting performed under the above cutting conditions corresponds to cutting performed under conditions where the cutting edge temperature is high.

[0154] The cutting tools of Samples 51 to 85 correspond to Examples, and the cutting tools of Samples 151 to 176 correspond to Comparative Examples. It was confirmed that the cutting tools of Samples 51 to 85 have a longer tool life in cutting operations performed under conditions of high cutting edge temperatures than the cutting tools of Samples 151 to 176.

[0155] <Cutting Test 4: Milling Test> For each sample, the SEMT13T3AGSN-shaped cutting tool was surface milled under the following cutting conditions, aligning the centerline of a 150 mm-wide plate with the center of a wider φ160 mm cutter. The cutting length until the flank wear of the cutting edge reached 0.2 mm was measured. The results are shown in the "Cutting Length [km]" column of "Cutting Test 4" in Tables 5 and 6. Note that in Tables 5 and 6, a longer cutting length indicates a longer tool life. <Cutting Conditions> Workpiece: FCD700 (HB = 250); Cutting Speed: 220 m / min; Feed Rate: 0.2 mm / tooth; Axial Depth of Cut (ap): 2.0 mm; Radial Depth of Cut (ae): 150 mm; Coolant: Dry. The cutting performed under the above cutting conditions corresponds to cutting performed under conditions of high cutting edge temperatures.

[0156] The cutting tools of Samples 51 to 85 correspond to Examples, and the cutting tools of Samples 151 to 176 correspond to Comparative Examples. It was confirmed that the cutting tools of Samples 51 to 85 have a longer tool life in cutting operations performed under conditions of high cutting edge temperatures than the cutting tools of Samples 151 to 176.

[0157] Although the embodiments and examples of the present disclosure have been described above, it is intended from the beginning that the configurations of the above-described embodiments and examples may be appropriately combined and modified in various ways. The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments and examples, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

[0158] 1 Cutting tool, 2 Substrate, 3 Coating, 12 First unit layer, 13 First layer, 13A Second layer, 14 Surface layer, 15 Second unit layer, 16 Base layer, 17 Third unit layer, 101 Chamber, 102 Gas, 103 Gas outlet, 104 Substrate holder, 105 Gas inlet, 106, 107, 120 Cathode, 108, 109 Arc power supply, 110 Bias power supply.

Claims

1. A cutting tool comprising a substrate and a coating disposed on the substrate, the coating including a first layer, the first layer being composed of an alternating layer in which a first unit layer and a second unit layer are alternately laminated, the first unit layer consisting of Ti １－ａ Mo ａ N, where a is 0.01 or more and 0.20 or less, the second unit layer consisting of Al ｂ V １－ｂ N, where b is 0.40 or more and 0.80 or less, the cutting tool.

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

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

4. The coating further includes a surface layer provided on the side opposite to the base material of the first layer, and the surface layer is made of TiMoON or AlVON. The cutting tool according to any one of claims 1 to 3.

5. A cutting tool comprising a substrate and a coating disposed on the substrate, wherein the coating includes a second layer, the second layer is composed of an alternating layer in which a first unit layer and a third unit layer are alternately laminated, the first unit layer is composed of Ti １－ａ Mo ａ N, where a is 0.01 or more and 0.20 or less, the third unit layer is composed of Al ｃ V １－ｃ－ｄ X ｄ N, where X is one or two selected from the group consisting of boron, silicon, scandium, yttrium, and cerium, c is 0.40 or more and 0.80 or less, and d is 0.001 or more and 0.05 or less. Cutting tool.

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

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

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

Images