Hard coating for cutting tools

Abstract

[Problem] To provide a hard coating film for cutting tools having excellent wear resistance. [Means for solving the problem] A hard coating film for cutting tools, comprising a first coating layer in contact with a workpiece, the first coating layer being layered with at least one of a nitride layer A composed of Al and Cr and containing unavoidable impurities, a nitride layer B composed of Al, Cr, and Cu and containing unavoidable impurities, and a nitride layer C composed of Al and four elements selected from Ti, Nb, Cr, V, Ta, Zr, and B and containing unavoidable impurities, further, the amount of Cu in the nitride layer B being 5 mol% or less, and further, the amount of Al in the nitride layer C being 30 mol% or more and 60 mol% or less, and the amounts of the above elements other than Al being equal ± 5 mol% (where equal = (100 - the amount of Al in the above nitride layer C) / 4).

Description

TECHNICAL FIELD

[0001] The present application relates to a hard coating film for cutting tools, which is coated on a cutting tool such as an end mill, a drill, and the like. BACKGROUND

[0002] As a hard coating film for cutting tools, which is coated on a cutting tool such as an end mill, a drill, and the like, AlCrN disclosed in Patent Literature 1 is known as a film having excellent wear resistance.

[0003] Since the AlCrN also has excellent heat resistance, it is widely used as a hard coating film for cutting tools.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 10-25566 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The present inventors have further researched and developed a hard coating film for cutting tools having excellent wear resistance and heat resistance as described above, and have developed a hard coating film for cutting tools of a new era, which exhibits excellent wear resistance compared to a conventional hard coating film for cutting tools composed of a single layer of AlCrN (hereinafter, referred to as "conventional example").

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] The gist of the present application will be described.

[0011] A hard coating film for cutting tools, which is formed on a substrate, characterized by comprising a first coating layer in contact with a workpiece, the first coating layer being formed by laminating at least one of a nitride layer A composed of Al and Cr and containing inevitable impurities, a nitride layer B composed of Al, Cr, and Cu and containing inevitable impurities, and a nitride layer C composed of Al and four elements selected from Ti, Nb, Cr, V, Ta, Zr, and B and containing inevitable impurities, further, the amount of Cu in the nitride layer B being 5 mol% or less, and the amount of Al in the nitride layer C being 30 mol% or more and 60 mol% or less, and the amounts of the respective elements other than Al being equal ± 5 mol% (where equal = (100 - the amount of Al in the nitride layer C) / 4) (Technical Solution 1).

[0012] Further, the hard coating film for cutting tools according to the above-mentioned technical solution 1 is characterized in that the first coating layer is composed of the nitride layer A and the nitride layer C laminated in multiple layers (technical solution 2).

[0013] Further, the hard coating film for cutting tools according to the above-mentioned technical solution 1 is characterized in that the first coating layer is composed of the nitride layer B and the nitride layer C laminated in multiple layers (technical solution 3).

[0014] Further, the hard coating film for cutting tools according to the above-mentioned technical solution 1 is characterized in that the first coating layer is composed of the nitride layer A, the nitride layer B and the nitride layer C laminated in multiple layers (technical solution 4).

[0015] Further, the hard coating film for cutting tools according to any one of the above-mentioned technical solutions 1 to 4 is characterized in that the hard coating film for cutting tools is composed of the first coating layer and a second coating layer provided below the first coating layer, the second coating layer is composed of a nitride layer D or a nitride layer E, the nitride layer D is composed of Al and Cr and contains inevitable impurities, the nitride layer E is composed of Al, Cr and Cu and contains inevitable impurities, further, the amount of Cu in the nitride layer E is 5 mol% or less (technical solution 5).

[0016] Further, the hard coating film for cutting tools according to the above-mentioned technical solution 5 is characterized in that the second coating layer is the nitride layer D, and further, the amount of Cr in the nitride layer D is 30 mol% or more and 50 mol% or less (technical solution 6).

[0017] Further, the hard coating film for cutting tools according to the above-mentioned technical solution 5 is characterized in that the nitride layer D and the nitride layer A have the same composition (technical solution 7).

[0018] Further, the hard coating film for cutting tools according to the above-mentioned technical solution 6 is characterized in that the nitride layer D and the nitride layer A have the same composition (technical solution 8).

[0019] Further, the hard coating film for cutting tools according to the above-mentioned technical solution 5 is characterized in that the second coating layer is the nitride layer E, and further, the amount of Cr in the nitride layer E is 30 mol% or more and 50 mol% or less (technical solution 9).

[0020] Further, the hard coating film for cutting tools according to the above-mentioned technical solution 5 is characterized in that the nitride layer E and the nitride layer B have the same composition (technical solution 10).

[0021] Further, the hard coating film for cutting tools according to any one of the aspects 1 to 4 is characterized in that the hard coating film for cutting tools is composed of the first coating layer and a second coating layer provided below the first coating layer, the second coating layer is composed of a nitride layer D and a nitride layer E, the nitride layer D is composed of Al and Cr and contains inevitable impurities, the nitride layer E is composed of Al, Cr, and Cu and contains inevitable impurities, and further, the amount of Cu in the nitride layer E is 5 mol% or less (aspect 12).

[0022] Further, the hard coating film for cutting tools according to any one of the aspects 1 to 4 is characterized in that the hard coating film for cutting tools is composed of the first coating layer and a second coating layer provided below the first coating layer, the second coating layer is composed of a nitride layer D and a nitride layer E, the nitride layer D is composed of Al and Cr and contains inevitable impurities, the nitride layer E is composed of Al, Cr, and Cu and contains inevitable impurities, and further, the amount of Cu in the nitride layer E is 5 mol% or less (aspect 12).

[0023] Further, the hard coating film for cutting tools according to aspect 12 is characterized in that the average value of the amount of Cr in each of the nitride layer D and the nitride layer E of the second coating layer is about 30 mol% or more and 50 mol% or less (aspect 13).

[0024] Further, the hard coating film for cutting tools according to aspect 12 is characterized in that the nitride layer D and the nitride layer A are of the same composition, and further, the nitride layer E and the nitride layer B are of the same composition (aspect 14).

[0025] Further, the hard coating film for cutting tools according to aspect 13 is characterized in that the nitride layer D and the nitride layer A are of the same composition, and further, the nitride layer E and the nitride layer B are of the same composition (aspect 15).

[0026] Further, the hard coating film for cutting tools according to aspect 12 is characterized in that the second coating layer is composed of the nitride layer D and the nitride layer E laminated in multiple layers (aspect 16).

[0027] Further, the hard coating film for cutting tools according to aspect 13 is characterized in that the second coating layer is composed of the nitride layer D and the nitride layer E laminated in multiple layers (aspect 17).

[0028] Further, the hard coating film for cutting tools according to aspect 14 is characterized in that the second coating layer is composed of the nitride layer D and the nitride layer E laminated in multiple layers (aspect 18).

[0029] Further, the hard coating film for cutting tools according to aspect 15 is characterized in that the second coating layer is composed of the nitride layer D and the nitride layer E laminated in multiple layers (aspect 19).

[0030] Inventive Effects

[0031] The present application is configured as described above, and thus becomes a cutting tool hard coating that exhibits superior wear resistance compared to conventional examples.

[0032] Therefore, by coating the cutting tool with the cutting tool hard coating of the present application on the substrate of the cutting tool, compared to the case of coating the conventional example, it is possible to suppress damage to the cutting tool, and extend tool life. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 (A) is a crystal structure diagram (reflection electron image) of one specific example (AlTiNbCrVN) of the nitride layer C of the present application, and (B) is a crystal structure diagram (reflection electron image) of a conventional example. DETAILED DESCRIPTION

[0034] Based on the drawings, a preferred embodiment of the present application is briefly described, showing the effects of the present application.

[0035] Figure 1 (A) is a crystal structure diagram (reflection electron image) of one specific example (AlTiNbCrVN) of the nitride layer C of the present application, and (B) is a crystal structure diagram (reflection electron image) of a conventional example.

[0036] As shown in (A) of FIG. 1, compared to the conventional example of (B), the nitride layer C of the present application has small crystal grains, and thus it is possible to expect effects such as suppression of the propagation of cracks at the grain boundaries, an increase in hardness due to the Hall-Petch effect, and the like, and it is possible to obtain superior wear resistance (this is considered to be due to the fact that the nitride layer C of the present application contains a plurality of metal elements, and thus the mixing entropy is high, like a high-entropy alloy, and high-entropy effects, lattice distortion effects, and low diffusivity are exhibited). Note that in the present specification, the above-mentioned metal elements also include semi-metal elements. Figure 1 The present application is a cutting tool hard coating that exhibits more superior wear resistance than AlCrN, due to the fact that the first coating layer that comes into contact with the workpiece contains the above-mentioned nitride layer C, compared to the case of coating the conventional example, it is possible to suppress damage to the cutting tool, and extend tool life.

[0037] Example 1

[0038] A specific example 1 of the present application is described.

[0039]

[0040] ​The hard coating for cutting tools of the present embodiment is formed on a substrate, and the first coating layer that contacts a workpiece to be cut is formed by laminating at least one of a nitride layer A (hereinafter, referred to as "nitride layer A") composed of Al and Cr and containing inevitable impurities, and a nitride layer B (hereinafter, referred to as "nitride layer B") composed of Al, Cr, and Cu and containing inevitable impurities, and a nitride layer C (hereinafter, referred to as "nitride layer C") composed of Al and four metal elements selected from Ti, Nb, Cr, V, Ta, Zr, B and containing inevitable impurities.

[0041] Specifically, the hard coating for cutting tools of the present embodiment is composed of: the first coating layer (the outermost layer); the second coating layer (the intermediate layer) composed of a nitride layer D (hereinafter, referred to as "nitride layer D") composed of Al and Cr and containing inevitable impurities, and a nitride layer E (hereinafter, referred to as "nitride layer E") composed of Al, Cr, and Cu and containing inevitable impurities, which are laminated directly below the first coating layer; and the base layer (the adhesion layer) composed of a nitride or carbonitride mainly composed of Ti, which is located directly below the second coating layer and is disposed directly above the substrate.

[0042] Hereinafter, each part of the present embodiment will be described in detail.

[0043] The first coating layer of the present embodiment is formed by laminating the nitride layer A, the nitride layer B, and the nitride layer C.

[0044] Specifically, the nitride layer A is composed of AlCrN in which the metal components are Al (m) Cr (n) (wherein, m+n=100), contains at least N as a non-metal element, and contains inevitable impurities.

[0045] More specifically, the nitride layer A of the present embodiment is composed of (Al 70 Cr 30 )N, and the thickness is set to 0.01 μm to 0.02 μm.

[0046] Note that the nitride layer A is not limited to the above (Al 70 Cr 30 )N, and may be, for example, (Al 60 Cr 40 )N, (Al 50 Cr 50 )N, or (Al 40 Cr 60 )N.

[0047] Further, the nitride layer B is composed of AlCrCuN in which the metal components are expressed in terms of mol% as Al (x) Cr (y) Cu (z) (wherein x+y+z=100, and 0

[0048] Specifically, the nitride layer B of the present embodiment is composed of (Al 49.5 Cr 49.5 Cu1)N, and the thickness is set to 0.01 μm to 0.02 μm.

[0049] Note that, in the nitride layer B, as described above, the Cu content can be applied within the range of 0 49.5 Cr 49.5 Cu1)N, for example, (Al 49.5 Cr 49.5 Cu1)N, (Al 49 Cr 49 Cu2)N, (Al 47.5 Cr 47.5 Cu5)N.

[0050] Further, in a case where four metal elements other than Al (four metal elements selected from Ti, Nb, Cr, V, Ta, Zr, B) are set as X1, X2, X3, X4, the nitride layer C is composed of AlX1X2X3X4N in which the metal components are expressed in terms of mol% as Al (a) X1 (b1) X2 (b2) X3 (b3) X4 (b4) (wherein a+b1+b2+b3+b4=100, 30 mol%≤a≤60 mol%, b1=b±5 mol%, b2=b±5 mol%, b3=b±5 mol%, b4=b±5 mol%, b=(100-a) / 4), as a nonmetal element, at least N is contained, and unavoidable impurities are contained (wherein X1, X2, X3, X4 are four metal elements selected from Ti, Nb, Cr, V, Ta, Zr, B).

[0051] Specifically, the nitride layer C of the present embodiment is composed of AlTiNbCrVN, as four metal elements other than Al, Ti, Nb, Cr, V are selected, and the metal components are expressed in terms of mol% as Al (a) Ti (b1) Nb (b2) Cr (b3) V (b4)(wherein, a + b1+ b2+ b3+ b4= 100, 30 < a < 60, b1= b±5, b2= b±5, b3= b±5, b4= b±5, b = (100 - a) / 4), contains at least N as a nonmetal element, and contains unavoidable impurities.

[0052] More specifically, the nitride layer C of the present embodiment is composed of (Al 40 Ti 15 Nb 15 Cr 15 V 15 )N, and the thickness is set to 0.01 μm to 0.02 μm.

[0053] Note that, in the nitride layer C, as described above, the content of Al can be applied within the range of 30 < a < 60 (mole %), and therefore, the nitride layer C is not limited to the above (Al 40 Ti 15 Nb 15 Cr 15 V 15 )N, and can be, for example, (Al 30 Ti 17.5 Nb 17.5 Cr 17.5 V 17.5 )N, (Al 50 Ti 12.5 Nb 12.5 Cr 12.5 V 12.5 )N, or (Al 60 Ti 10 Nb 10 Cr 10 V 10 )N.

[0054] Further, in the nitride layer C, the metal components other than Al are preferably equal in amount, but as described above, an amount of deviation of 5 mole % or less from the equal amount can be applied, and therefore, for example, it can be set to (Al 40 Ti 20 Nb 10 Cr 15 V 15 )N, (Al 40 Ti 10 Nb 20 Cr 15 V 15 )N, or (Al 40 Ti 15 Nb 15 Cr 10 V 20 )N.

[0055] Further, regarding the nitride layer C, as the four kinds of metal elements other than Al, a combination other than Ti, Nb, Cr, and V can also be used. That is, for example, AlTiNbCrTaN (V is replaced with Ta), AlTiNbCrZrN (V is replaced with Zr), AlTiNbCrBN (V is replaced with B), AlTiCrZrBN (Nb and V are replaced with Zr and B), AlNbCrTaBN (Ti and V are replaced with Ta and B), AlTiNbZrBN (Cr and V are replaced with Zr and B) can also be used.

[0056] The first coating layer of the present embodiment is a multilayer in which these layers are alternately (sequentially) stacked, and in the present embodiment, a stacked layer of nitride layer A / nitride layer C / nitride layer B, that is, (Al 70 Cr 30 )N / (Al 40 Ti 15 Nb 15 Cr 15 V 15 )N / (Al 49.5 Cr 49.5 Cu1)N is repeatedly formed. Note that in the first coating layer, the outermost layer can be any of the nitride layer A, the nitride layer B, and the nitride layer C.

[0057] Further, the second coating layer provided immediately below the above first coating layer and serving as the intermediate layer of the present embodiment is a stacked layer of a nitride layer D and a nitride layer E.

[0058] Specifically, the nitride layer D is composed of AlCrN in which the metal components are Al (m) Cr (n) (wherein m+n=100), contains at least N as a nonmetal element, and contains unavoidable impurities.

[0059] More specifically, the nitride layer D of the present embodiment is composed of (Al 70 Cr 30 )N, and the thickness is set to 0.01 μm to 0.02 μm.

[0060] Further, the nitride layer E is composed of AlCrCuN in which the metal components are Al (x) Cr (y) Cu (z) (wherein x+y+z=100, and 0

[0061] Specifically, the nitride layer E of the present embodiment is composed of (Al 49.5 Cr49.5 Cu1)N, and the thickness is set to 0.01 μm to 0.02 μm.

[0062] That is, in the present embodiment, the nitride layer D of the second film layer is of the same composition as the nitride layer A of the first film layer, and in addition, the nitride layer E of the second film layer is of the same composition as the nitride layer B of the first film layer.

[0063] The second film layer of the present embodiment is configured by repeating the layering of these layers in alternation (in succession), and specifically, becomes a multilayer of the nitride layer D / nitride layer E, that is, (Al 70 Cr 30 )N / (Al 49.5 Cr 49.5 Cu1)N in this order. Note that in the second film layer, the outermost layer, that is, the boundary layer with the first film layer can be either of the nitride layer D and the nitride layer E. In addition, in the second film layer of the present embodiment, as described above, the nitride layer D is a nitride layer of the same composition ratio as the nitride layer A of the first film layer, and the nitride layer E is a nitride layer of the same composition ratio as the nitride layer B of the first film layer, but the nitride layer D and the nitride layer E can also be of different compositions from the nitride layer A and the nitride layer B of the first film layer, respectively.

[0064] In addition, in the second film layer, the amount of Cr in the nitride layer D and the amount of Cr in the nitride layer E are set so that the average of the amount of Cr in the nitride layer D and the amount of Cr in the nitride layer E is about 30 mol% or more and 50 mol% or less (preferably, 40 mol% or more and 50 mol% or less).

[0065] In other words, in the second film layer, if the average of the amount of Cr in the nitride layer D and the amount of Cr in the nitride layer E is about 30 mol% or more and 50 mol% or less, good wear resistance can be exhibited.

[0066] Therefore, in the second film layer, the layer configuration is not limited to the above (Al 70 Cr 30 )N / (Al 49.5 Cr 49.5 Cu1)N, and can be, for example, (Al 50 Cr 50 )N / (Al 49.5 Cr 49.5 Cu1)N, (Al 60 Cr 40 )N / (Al 49.5 Cr 49.5 Cu1)N, (Al 70 Cr 30)N / (Al 39.6 Cr 59.4 Cu1)N、(Al 70 Cr 30 )N / (Al 59.4 Cr 39.6 Cu1)N、(Al 40 Cr 60 )N / (Al 59.4 Cr 39.6 Cu1)N、(Al 70 Cr 30 )N / (Al 69.5 Cr 29.5 Cu1)N。

[0067] In addition, the base layer provided immediately below the second coating layer and immediately above the substrate, which is the adhesion layer in the present embodiment, is composed of TiN. This base layer serves to improve the adhesion of the substrate to the second coating layer. If the thickness of the base layer is too thin, the effect of improving the adhesion is reduced. If the thickness of the base layer is too thick, on the other hand, the hardness of the hard coating for cutting tools as a whole is reduced, so it is preferable to form the base layer to an appropriate thickness (0.1 to 0.5 μm in the present embodiment).

[0068] Note that, as the base layer, a nitride or a carbonitride in which Cr is used instead of Ti as the main component can also be used.

[0069] In addition, the hard coating for cutting tools of the present embodiment can also be configured as a multilayer coating in which the first coating layer and the second coating layer described above are alternately stacked in multiple layers. That is, for example, the configuration can be such that the stacked layer of the first coating layer / second coating layer is provided as one group, and multiple groups (for example, four groups) of the stacked layer are stacked.

[0070] Next, the reason why the first coating layer is configured as described above in the present embodiment will be described below.

[0071] The first coating layer of the present embodiment was determined as follows: Various experiments and studies were repeated, and for the hard coatings for cutting tools of A1 to A24 shown in Table 1 below, the following Experiment 1 was performed in order to confirm the wear resistance, and the results of Experiment 1 were used to determine the first coating layer.

[0072] <Experiment 1>

[0073] A first coating layer composed of the layers shown in A1 to A24 of Table 1 was formed on a substrate (made of superhard alloy containing WC (tungsten carbide) and Co (cobalt)) of each cutting tool by arc ion plating, and the wear width of the cutting tool hard coating on the flank face when cutting a workpiece (carbon steel) under the following cutting conditions A was measured in each cutting tool. Note that in this experiment, TiN was formed as a base layer directly above the substrate, and the first coating layer was formed on the TiN.

[0074] <cutting conditions A>

[0075] Tool: double-end ball nose end mill made of superhard alloy

[0076] Tool diameter: 3.0 mm

[0077] Coolant: water-soluble cutting oil

[0078] Rotational speed: 20,000 rpm

[0079] Feed rate: 2.0 m / min

[0080] Axial depth of cut: 0.32 mm

[0081] Radial depth of cut: 0.9 mm

[0082] Machining method: pocket machining (length 195 mm x width 45 mm x depth 2.0 mm)

[0083] [Table 1]

[0084]

[0085] As shown in Table 1, the results were that the wear width was the same or more than in the conventional examples (A1 and A2) in A17, A20, A23, and A24. Of these, A20, A23, and A24 were the results of a smaller wear width (good wear resistance) than the conventional examples, but in A20 and A23, a large number of spatters were confirmed to have been generated (considered to be caused by Ta) compared with the other examples including the conventional examples.

[0086] Based on the above results, in this example, the structure shown in A24 (i.e., (Al 70 Cr 30 )N was used as the nitride layer A, (Al 49.5 Cr 49.5 Cu1)N was used as the nitride layer B, and (Al 40 Ti 15 Nb 15 Cr 15 V15 )N as the nitride layer C of (Al 70 Cr 30 )N / (Al 40 Ti 15 Nb 15 Cr 15 V 15 )N / (Al 49.5 Cr 49.5 Cu1)N as the first coating layer.

[0087] Next, an experimental example for confirming the effects of the above-mentioned constitution except for (Al 70 Cr 30 )N) / (Al 40 Ti 15 Nb 15 Cr 15 V 15 )N / ((Al 49.5 Cr 49.5 Cu1)N in the first coating layer of the present embodiment will be described.

[0088] <Experiment 2>

[0089] Experiment 2 is an experiment for confirming the appropriate range of the amount of Al in the nitride layer C of the first coating layer.

[0090] Specifically, in Experiment 2, the cutting tool hard coating of A25 to A27 shown in Table 2 below, in which the amount of Al in the nitride layer C was changed, was measured for the wear width in the same experimental method as in Experiment 1 above (the cutting machining conditions were also the same).

[0091] [Table 2]

[0092]

[0093] As shown in Table 2, a result of equal to or less than the wear width was obtained in A25 and A26 compared with the wear width of A24 of Experiment 1: 59 μm.

[0094] From the above, it was confirmed that the appropriate range of the amount of Al in the nitride layer C of the first coating layer is 30 mol% or more and 60 mol% or less, and if the amount of Al in the nitride layer C is within this range, good wear resistance can be exerted.

[0095] <Experiment 3>

[0096] Experiment 3 is an experiment for confirming the appropriate range of the amount of metal components other than Al in the nitride layer C of the first coating layer.

[0097] Specifically, in Experiment 3, the wear width was measured for the cutting tool hard coating of A28 to A36 shown in Table 3 below, in which the amount of the metal component other than Al in the nitride layer C was changed (the amount of the metal component other than Al was made non-constant), using the same experimental method as in Experiment 1 above (the cutting process conditions were also the same).

[0098] [Table 3]

[0099]

[0100] As shown in Table 3, the results obtained were that, while not becoming a better wear width than A24, the wear width was approximately the same as that of A24 in A28, A29, and A36, as compared with the wear width of A24 of Experiment 1: 59 μm.

[0101] From the above, it was confirmed that the metal component other than Al in the nitride layer C of the first coating layer is preferably constant, but if it is within a range of a deviation of 5 mol% or less from the constant value, a good wear resistance can be exhibited.

[0102] [Experiment 4]

[0103] Experiment 4 is an experiment for confirming the wear resistance when a combination of four metal elements other than Ti, Nb, Cr, and V is selected as the metal component other than Al in the nitride layer C of the first coating layer.

[0104] Specifically, in Experiment 4, the wear width was measured for the cutting tool hard coating of A37 to A43 shown in Table 4 below, in which the combination of the four metal elements other than Al in the nitride layer C was changed, using the same experimental method as in Experiment 1 above (the cutting process conditions were also the same).

[0105] [Table 4]

[0106]

[0107] As shown in Table 4, the results obtained were that, while not becoming a better wear width than A24, the wear width was approximately the same as that of A24 in A38 to A42, as compared with the wear width of A24 of Experiment 1: 59 μm.

[0108] From the above, it was confirmed that even if a part of the metal elements Ti, Nb, Cr, and V other than Al in the nitride layer C of the first coating layer is replaced with Ta, Zr, and B, a good wear resistance can be exhibited.

[0109] In addition, the reason why the second coating layer is made into the above-described configuration in the present embodiment will be described below.

[0110] The second coating layer in this embodiment was determined as follows: various experiments and studies were repeatedly conducted in the same manner as the first coating layer. Finally, for the hard coatings for cutting tools B2 to B6 shown in Table 5, the following experiment 5 was conducted to confirm the wear resistance, and the determination was based on the results of experiment 5.

[0111] <Experiment 5>

[0112] A second film layer with the compositions shown in B2-B6 of Table 5 was formed on a substrate of the cutting tool (made of a superhard alloy containing WC (tungsten carbide) and Co (cobalt)) by arc ion plating. On this second film layer, an Al-coated alloy was formed, the composition determined in Experiment 1. 70 Cr 30 )N / (Al 40 Ti 15 Nb 15 Cr 15 V 15 )N / (Al 49.5 Cr 49.5 Using Cu1)N as the first film layer, the wear width of the cutting tool hard film on the flank face of the workpiece (pre-hardened steel) was measured when various cutting tools were used to cut the workpiece (pre-hardened steel) under the following cutting conditions B. Furthermore, B1 is a conventional example with the same structure as A1 in Experiment 1. In this experiment, TiN was formed directly above the substrate as a base layer (adhesive layer), and on this TiN, B1 formed the first film layer, and B2 to B6 formed the second film layers.

[0113] In addition, in this experiment, the thickness of the first membrane layer was approximately 1.2 μm, and the thickness of the second membrane layer was approximately 2.4 μm.

[0114] <Cutting Condition B>

[0115] Tools: Carbide double-edged ball end mill

[0116] Cutting diameter: 3.0mm

[0117] Coolant: Water-soluble cutting oil

[0118] Speed: 20,000 RPM

[0119] Feed rate: 2.0 m / min

[0120] Axial cut-in: 0.32mm

[0121] Radial penetration depth: 0.9mm

[0122] Machining method: Milling the pocket (195mm long x 30mm wide x 3.0mm deep)

[0123] [Table 5]

[0124]

[0125] As shown in Table 5, the following results were obtained: all of the cutting tool hard coatings of B2 to B6 in which the second coating layer was provided under the first coating layer had a smaller wear width (improved wear resistance) than the conventional example (Bl). Among them, B4 in which the second coating layer was provided as (Al 70 Cr 30 )N / (Al 49.5 Cr 49.5 Cu1)N was the result of having the smallest wear width (excellent wear resistance).

[0126] Based on the above results, in the present embodiment, the configuration shown in B4 in which the wear width was small (improved wear resistance) was adopted as the second coating layer (i.e., the multilayer coating layer of (Al 70 Cr 30 )N as the nitride layer D, and (Al 49.5 Cr 49.5 Cu1)N as the nitride layer E. 70 Cr 30 )N / (Al 49.5 Cr 49.5 Cu1)N was adopted.

[0127] Next, an experimental example for demonstrating the effects of the above-described configuration of the second coating layer in the present embodiment, except for (Al 70 Cr 30 )N / (Al 49.5 Cr 49.5 Cu1)N, will be described.

[0128] <Experiment 6>

[0129] Experiment 6 is an experiment for confirming the appropriate range of the amount of Cu in each of the nitride layers of the nitride layer B of the first coating layer and the nitride layer E of the second coating layer.

[0130] Specifically, in Experiment 6, the wear widths of the cutting tool hard coatings of B7 to B10 shown in Table 6 below, in which the amount of Cu in each of the nitride layers of the nitride layer B of the first coating layer and the nitride layer E of the second coating layer was changed, were measured in the same experimental method as in Experiment 5 above (the cutting processing conditions were also the same).

[0131] [Table 6]

[0132]

[0133] As shown in Table 6, the results were that the wear width was smaller (wear resistance was improved) in B7 to B9 than in the conventional example (B1 of Experiment 5) : 50.2 μm, and the wear width of B8 and B9 was about the same as that of B3 of Experiment 5.

[0134] From the above, it was confirmed that, according to the results of Experiment 5, if the amount of Cu in each of the nitride layer B of the first film layer and the nitride layer E of the second film layer is greater than 0 and 5 mol% or less, good wear resistance can be exhibited.

[0135] <Experiment 7>

[0136] Experiment 7 is an experiment for confirming the appropriate range of the amount of Cr in each of the nitride layer D and the nitride layer E of the second film layer.

[0137] Specifically, in Experiment 7, the wear width was measured for the hard film for cutting tools of B11 to B17 shown in Table 7 below, in which the amount of Cr in each of the nitride layer D and the nitride layer E of the second film layer was changed, in the same experimental method as in Experiment 5 described above (the cutting processing conditions were also the same).

[0138] [Table 7]

[0139]

[0140] As shown in Table 7, the results were that the wear width was smaller (wear resistance was improved) in all but B12 than in the conventional example (B1 of Experiment 5) : 50.2 μm.

[0141] In B12, the average of the amount of Cr in the nitride layer D and the amount of Cr in the nitride layer E was greater than 50 mol% (about 55 mol%), and, except for this B12, the average of the amount of Cr in the nitride layer D and the amount of Cr in the nitride layer E was about 30 mol% or more and 50 mol% or less.

[0142] From the above, it was confirmed that, in the second film layer, if the average of the amount of Cr in the nitride layer D and the amount of Cr in the nitride layer E is about 30 mol% or more and 50 mol% or less (preferably, 40 mol% or more and 50 mol% or less), good wear resistance can be exhibited.

[0143] <Experiment 8>

[0144] Experiment 8 is an abrasion resistance test for confirming the case where the composition ratio of the nitride layer C of the first film layer is changed based on the results of Experiment 5 described above and Experiment 2 and Experiment 4 described above regarding the first film layer, specifically, the case where the amount of Al is changed (in this experiment, the case where the amount of Al is changed from 40 mol% to 60 mol%), and the case where a combination other than Ti, Nb, Cr, and V is selected as the composition of the four metal elements other than Al in the nitride layer C (in this experiment, the case where Ti, Nb, Cr, and B are selected (the case where V is replaced with B)).

[0145] Specifically, in Experiment 8, the abrasion width was measured for the cutting tool hard film of B18, 19 shown in Table 8 using the same experimental method as Experiment 5 described above (the cutting processing conditions were also the same).

[0146] [Table 8]

[0147]

[0148] As shown in Table 8, the results obtained were that the abrasion width was smaller (the abrasion resistance was improved) in either of B18, 19 compared to the abrasion width of the conventional example (B1 of Experiment 5): 50.2 μm.

[0149] From the above, it can be confirmed that in the first film layer, if the amount of Al in the nitride layer C is 30 mol% or more and 60 mol% or less, good abrasion resistance can be exhibited, and even if a part of the metal elements Ti, Nb, Cr, and V other than Al in the nitride layer C is replaced with Ta, Zr, and B, good abrasion resistance can be exhibited.

[0150] Example 2

[0151] A specific example 2 of the present application will be described.

[0152] This example is a case where the composition (the constituent) of the nitride layer C of the first film layer of Example 1 is different.

[0153] Specifically, the nitride layer C of the first film layer of this example is a nitride layer composed of Al and 5 to 6 kinds of metal elements selected from Ti, Nb, Cr, V, Ta, Zr, and B and containing unavoidable impurities.

[0154] Hereinafter, this example will be described in detail, but in this example, the same as Example 1 except for the nitride layer C of the first film layer, and thus the description other than the nitride layer C is omitted.

[0155] The nitride layer C of the present embodiment is composed of AlTiNbCrVBN, Ti, Nb, Cr, V, and B are selected as the five metal elements other than Al, and the metal components are expressed in terms of mol% as Al (a) X1 (b1) X2 (b2) X3 (b3) X4 (b4) X5 (b5) (wherein a + b1+ b2+ b3+ b4+ b5= 100, 30 mol% ≤ a ≤ 60 mol%, b1= b±5 mol%, b2= b±5 mol%, b3= b±5 mol%, b4= b±5 mol%, b5= b±5 mol%, b= (100-a) / 5), and, in the case where the metal elements other than Al are selected from six metal elements (X1, X2, X3, X4, X5, X6) out of Ti, Nb, Cr, V, Ta, Zr, B, the metal components are expressed in terms of mol% as Al (a) X1 (b1) X2 (b2) X3 (b3) X4 (b4) X5 (b5) X6 (b6) (wherein a + b1+ b2+ b3+ b4+ b5+ b6= 100, 30 mol% ≤ a ≤ 60 mol%, b1= b±5 mol%, b2= b±5 mol%, b3= b±5 mol%, b4= b±5 mol%, b5= b±5 mol%, b6= b±5 mol%, b= (100-a) / 6).

[0156] Specifically, the nitride layer C of the present embodiment is composed of AlTiNbCrVBN, Ti, Nb, Cr, V, and B are selected as the five metal elements other than Al, and the metal components are expressed in terms of mol% as Al (a) Ti (b1) Nb (b2) Cr (b3) V (b4) B (b5) (wherein a + b1+ b2+ b3+ b4+ b5= 100, 30 ≤ a ≤ 60, b1= b±5, b2= b±5, b3= b±5, b4= b±5, b5= b±5 mol%, b= (100-a) / 5)), and contains at least N and unavoidable impurities as non-metal elements.

[0157] More specifically, the nitride layer C of the present embodiment is composed of (Al 40 Ti 12 Nb 12 Cr 12 V 12 B 12)N, the thickness is set to 0.01 to 0.02 μm.

[0158] Note that the nitride layer C is not limited to the above composition, and for example, Ta or Zr can be selected instead of B (B is replaced with Ta or Zr), and in addition, instead of replacing one kind as described above, a plurality of metal elements can be replaced. Further, the metal elements other than Al can be composed of six kinds of metal elements selected from Ti, Nb, Cr, V, Ta, Zr, and B (for example, AlTiNbZrCrVBN, etc.).

[0159] Next, experimental examples for demonstrating the effects of the present embodiment will be described.

[0160] <Experiment 9>

[0161] On the base material (superhard alloy containing WC (tungsten carbide) and Co (cobalt) ) of each cutting tool, a first coating layer composed of the layers shown in C1 and C2 of Table 9 was formed by arc ion plating, and in each cutting tool, the wear width of the cutting tool hard coating of the flank face when cutting processing was performed on a workpiece (carbon steel) under the following cutting processing conditions C was measured. Note that in this experiment, TiN was formed as a base layer directly above the base material, and the first coating layer was formed on the TiN.

[0162] <cutting processing conditions C>

[0163] Tool: superhard alloy double-edge ball-end mill

[0164] Tool diameter: 3.0 mm

[0165] Coolant: water-soluble cutting oil

[0166] Rotational speed: 20,000 / minute

[0167] Feed rate: 2.0 m / minute

[0168] Axial cut-in amount: 0.32 mm

[0169] Radial cut-in amount: 0.9 mm

[0170] Processing method: pocket processing (length 195 mm x width 45 mm x depth 2.0 mm)

[0171] [Table 9]

[0172]

[0173] As shown in Table 9, it was confirmed that the obtained results were: the wear width was equivalent or below that of the conventional example (A1 and A2 of Experiment 1 of Example 1), and the same degree of wear width (wear resistance) was also obtained as compared with A24 of Experiment 1 of Example 1.

[0174] <Experiment 10>

[0175] On a base material (made of superhard alloy containing WC (tungsten carbide) and Co (cobalt)) of a cutting tool, a second film layer and a first film layer having the composition shown in C3 of Table 10 were formed by an arc ion plating method, and the wear width of the cutting tool hard film on the flank face of the cutting tool when a cutting tool was used to cut a workpiece (pre-hardened steel) under the following cutting processing conditions D was measured.

[0176] Note that, in this experiment, TiN was formed as a base layer (adhesion layer) directly above the base material, and the second film layer was formed on the TiN. In addition, in this experiment, the thickness of the first film layer was about 1.2 μm, and the thickness of the second film layer was about 2.4 μm.

[0177] <cutting processing conditions D>

[0178] Tool: double-edged ball-end mill made of superhard alloy

[0179] Tool diameter: 3.0 mm

[0180] Coolant: water-soluble cutting oil

[0181] Rotational speed: 20,000 / minute

[0182] Feed rate: 2.0 m / minute

[0183] Axial cut-in amount: 0.32 mm

[0184] Radial cut-in amount: 0.9 mm

[0185] Processing method: pocket processing (length 195 mm x width 30 mm x depth 3.0 mm)

[0186] [Table 10]

[0187]

[0188] As shown in Table 10, it was confirmed that the obtained results were: the wear width was smaller (wear resistance was improved) as compared with the wear width: 50.2 μm of the conventional example (B1 of Experiment 5 of Example 1), and the same degree of wear width (wear resistance) was also obtained as compared with B3 of Experiment 5 of Example 1.

[0189] Note that the present application is not limited to Embodiments 1 and 2, and each of the constituent elements can be designed as appropriate.

Claims

1. A hard coating for cutting tools, which is a hard coating for cutting tools formed on a substrate, characterized by, The cutting tool hard coating film includes a first coating layer in contact with a workpiece to be cut, the first coating layer being formed by laminating at least one of a nitride layer A composed of Al and Cr and containing unavoidable impurities and a nitride layer B composed of Al, Cr, and Cu and containing unavoidable impurities, and a nitride layer C composed of Al and four elements selected from Ti, Nb, Cr, V, Ta, Zr, B and containing unavoidable impurities, further, in the nitride layer B, the amount of Cu is 5 mol% or less relative to the total of metal elements in the nitride layer B, and in the nitride layer C, the amount of Al is 30 mol% or more and 60 mol% or less relative to the total of metal elements in the nitride layer C, and the amounts of the respective elements other than Al are equal ± 5 mol% to the equal amount = (100 - the amount of Al in the nitride layer C) / 4.

2. The hard coating film for cutting tools according to claim 1, characterized by, The first coating layer is formed by laminating the nitride layer A and the nitride layer C in multiple layers.

3. The hard coating film for cutting tools according to claim 1, wherein The first coating layer is formed by laminating the nitride layer B and the nitride layer C in multiple layers.

4. The hard coating film for cutting tools according to claim 1, wherein The first coating layer is formed by laminating the nitride layer A, the nitride layer B, and the nitride layer C in multiple layers.

5. The hard coating film for cutting tools according to any one of claims 1 to 4, characterized in that, The cutting tool hard coating film is composed of the first coating layer and a second coating layer provided below the first coating layer, the second coating layer being composed of a nitride layer D composed of Al and Cr and containing unavoidable impurities or a nitride layer E composed of Al, Cr, and Cu and containing unavoidable impurities, further, in the nitride layer E, the amount of Cu is 5 mol% or less relative to the total of metal elements in the nitride layer E.

6. The hard coating film for cutting tools according to claim 5, characterized by The second coating layer is the nitride layer D, and in the nitride layer D, the amount of Cr is 30 mol% or more and 50 mol% or less relative to the total of metal elements in the nitride layer D.

7. The hard coating film for cutting tools according to claim 5, wherein The nitride layer D and the nitride layer A have the same composition.

8. The hard coating film for cutting tools according to claim 6, wherein The nitride layer D and the nitride layer A have the same composition.

9. The hard coating film for cutting tools according to claim 5, wherein The second coating layer is the nitride layer E, and in the nitride layer E, the amount of Cr is 30 mol% or more and 50 mol% or less relative to the total of metal elements in the nitride layer E.

10. The hard coating film for cutting tools according to claim 5, characterized by, The nitride layer E and the nitride layer B have the same composition.

11. The hard coating film for cutting tools according to claim 9, wherein The nitride layer E and the nitride layer B have the same composition.

12. The hard coating film for cutting tools according to any one of claims 1 to 4, characterized in that, The cutting tool hard coating film is composed of the first coating layer and a second coating layer provided below the first coating layer, the second coating layer being formed by laminating a nitride layer D composed of Al and Cr and containing unavoidable impurities or a nitride layer E composed of Al, Cr, and Cu and containing unavoidable impurities, further, in the nitride layer E, the amount of Cu is 5 mol% or less relative to the total of metal elements in the nitride layer E.

13. The cutting tool hard coating according to claim 12, characterized by The amount of Cr in the nitride layer D with respect to the total of metal elements in the nitride layer D is 30 mol% or more and 50 mol% or less on average with respect to the amount of Cr in the nitride layer E with respect to the total of metal elements in the nitride layer E.

14. The cutting tool hard coating according to claim 12, wherein The nitride layer D and the nitride layer A are of the same composition, and the nitride layer E and the nitride layer B are of the same composition.

15. The cutting tool hard coating according to claim 13, wherein The nitride layer D and the nitride layer A are of the same composition, and the nitride layer E and the nitride layer B are of the same composition.

16. The cutting tool hard coating according to claim 12, wherein The second film layer is formed by laminating the nitride layer D and the nitride layer E in multiple layers.

17. The cutting tool hard coating according to claim 13, wherein The second film layer is formed by laminating the nitride layer D and the nitride layer E in multiple layers.

18. The cutting tool hard coating according to claim 14, wherein The second film layer is formed by laminating the nitride layer D and the nitride layer E in multiple layers.

19. The cutting tool hard coating according to claim 15, wherein The second film layer is formed by laminating the nitride layer D and the nitride layer E in multiple layers.

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