Hard Coating

Abstract

We provide hard coatings with low friction, high sliding properties, welding resistance, wear resistance, heat resistance, and improved adhesion. The hard coating formed on the substrate 1 includes an abrasion-resistant layer 3 formed on the substrate 1 and an adhesion-resistant layer 4 formed on the abrasion-resistant layer 3. The adhesion-resistant layer 4 has a composition of (Al 1-y-z Ti y Cr z )(C 1-a N a ), 0

Description

[Technical Field]

[0001] The present invention relates to a hard coating formed on a substrate. [Background technology]

[0002] In order to improve the durability of press dies, cutting tools, etc., press dies and cutting tools coated with nitrides such as TiN, TiAlN, and CrAlN have been put into practical use. In recent years, the workpieces machined with these press dies and cutting tools have become more difficult to cut and process, and machining conditions have also become more demanding. For this reason, press dies and cutting tools are required to have even longer lifespans that do not shorten even when machined under harsher machining conditions. Consequently, the hard coatings formed on the surfaces of press dies and cutting tools are required to have even higher performance in terms of durability.

[0003] When it comes to film performance, durability, it is important to have wear resistance and heat resistance. High wear resistance means that the hard film is less likely to be worn away during cutting or press processing using a mold, and high heat resistance means that the surface is less likely to oxidize even at higher temperatures when the mold or cutting tool becomes hot during processing. Other film performances include high adhesion resistance and a low friction coefficient, which affect the surface quality and release properties of the workpiece during processing.

[0004] In order to improve heat resistance, the properties of a TiAlN single layer film have been investigated (Patent Document 1), and a comparison between a TiAlN film and a CrAlN film has been made in terms of compatibility with the substrate (Patent Document 2). Other films aimed at improving heat resistance include a TiCrAlN film (Patent Document 3), an AlTiSiN film with added Si (Patent Document 4), and an AlCrSiN film (Patent Document 5). Furthermore, a TiCrAlYN film with excellent sliding properties has been proposed as a film for cold molds used at temperatures below 600°C (Patent Document 6).

[0005] On the other hand, lamination of coatings has been proposed, with the aim of stacking multiple single-layer films with different properties and simultaneously utilizing the characteristics and functions of each single-layer film. Patent Document 7 discloses a laminated film of TiAlN and TiVN films to enhance the wear resistance, adhesion resistance, and lubrication effect of cutting tools. Patent Document 8 also discloses that a coating formed by laminating a TiSiN film and a TiAlN film is effective for achieving high oxidation resistance and wear resistance. Patent Document 9 further discloses a two-layer film formed by stacking a highly oxidation-resistant and high-strength TiCrAlSiYN film on a highly tough TiCrAlN film. Patent Document 10 further discloses a coating formed by stacking an AlSiVCrN film on an upper layer and an AlCrN film on a lower layer, which improves heat resistance in addition to wear resistance and sliding properties. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 2644710 [Patent Document 2] Patent No. 4475230 [Patent Document 3] Patent No. 4112834 [Patent Document 4] Patent No. 2840541 [Patent Document 5] Patent No. 3640310 [Patent Document 6] Patent No. 5193153 [Patent Document 7] Patent No. 3836640 [Patent Document 8] Patent No. 3248897 [Patent Document 9] Patent No. 5730535 [Patent Document 10] Patent No. 6347566 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in press working using a die and cutting using a cutting tool, further higher efficiency is required, and the workability of the workpiece to be processed is becoming more difficult. In cutting, cutting of a wider range of parts is required, and cutting under more severe cutting conditions is required. In die processing, high performance of die processing in as many applications as possible, such as cold forging, hot forging, and hot stamping, is required. Therefore, further higher performance is required for the hard film. That is, a hard film with further improved low friction - high sliding characteristics, weld resistance, adhesion, wear resistance, and heat resistance is desired, and moreover, it is desired that these performances are exhibited under various processing conditions and for various workpieces.

[0008] The present invention has been made in view of such problems, and an object thereof is to provide a hard film with improved low friction - high sliding characteristics, weld resistance, adhesion, wear resistance, and heat resistance.

Means for Solving the Problems

[0009] One embodiment of the hard film of the present invention is a hard film formed on a substrate, comprising a wear - resistant layer formed on the substrate and an anti - seizure layer formed on the wear - resistant layer. The anti - seizure layer satisfies 0 < y ≤ 0.45, 0 < z ≤ 0.5, 0.6 ≤ a ≤ 0.9 (where y, z, and a all represent atomic ratios) when represented by the composition (Al 1-y-z Ti y Cr z )(C 1-a N a ), and has a smaller film hardness value compared to the wear - resistant layer. Here, the film hardness value is a value represented by an index indicating the degree of hardness of the film, for example, a hardness value obtained by a micro - Vickers test or a nano - indentation test.

[0010] In the above embodiment, the wear-resistant layer may have a composition of (Al,Ti,Cr)N. In the hard coating of the present invention, the wear-resistant layer is not limited to a composition of (Al,Ti,Cr)N, and may be any layer having a coating hardness greater than that of the adhesion-resistant layer. For example, the wear-resistant layer may be made of a nitride, carbide, carbonitride, boride, oxynitride, or oxycarbonitride of an alloy containing Al, Ti, and Cr and at least one element selected from the group consisting of Group 4a (excluding Ti), Group 5a, Group 6a (excluding Cr), Si, and Y.

[0011] Furthermore, a lower layer having a composition of (Al,Ti)N may be formed between the substrate and the wear-resistant layer. However, in the hard coating of the present invention, the lower layer is not limited to one made of (Al,Ti)N, and may be any layer that can improve the adhesion between the substrate and the wear-resistant layer.

[0012] Furthermore, the wear-resistant layer may include alternating layers in which a first laminate film having a composition of (Al,Ti,Cr)N and a second laminate film having a composition of (Al,Ti)N are alternately laminated.

[0013] Furthermore, the wear-resistant layer may be provided with a third stacked film, having a composition of (Al, Ti, Cr)N and having a thickness greater than that of the first stacked film and the second stacked film, immediately above the alternating layers and immediately below the adhesion-resistant layer.

[0014] Furthermore, the first stacked film, the third stacked film, and the adhesion-resistant layer may be formed by an arc ion plating method using the same target having a composition of (Al, Ti, Cr). Note that the first stacked film, the third stacked film, and the adhesion-resistant layer may be formed using targets having different compositions, or may be formed by a physical vapor deposition method other than the arc ion plating method, such as vacuum deposition or sputtering.

[0015] The lower layer and the second stacked film may be formed by an arc ion plating method using the same target having a composition of (Al, Ti). However, the lower layer and the second stacked film may be formed by using targets having different compositions, or may be formed by a physical vapor deposition method other than the arc ion plating method.

[0016] Furthermore, the composition of the lower layer is (Ti 1-x Al x )N, the atomic ratio may satisfy 0.4≦x≦0.7 (where x indicates the atomic ratio).

[0017] In the above embodiment in which the wear-resistant layer has a composition of (Al,Ti,Cr)N and the adhesion-resistant layer has a composition of (Al,Ti,Cr)CN, the wear-resistant layer may have an atomic ratio of Al and an atomic ratio of Ti that change in the film thickness direction from the lower layer side toward the adhesion-resistant layer side, and the atomic ratio of Cr in the film thickness direction may increase toward the adhesion-resistant layer side. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a hard coating having low friction, high sliding properties, improved adhesion, wear resistance, and heat resistance. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a diagram illustrating a first basic configuration of an embodiment of a hard coating. [Figure 2] FIG. 4 is a diagram illustrating a second basic configuration of an embodiment of a hard coating. [Figure 3] FIG. 10 is a diagram illustrating a third basic configuration of an embodiment of a hard coating. [Figure 4] FIG. 10 is a diagram illustrating a third basic configuration of an embodiment of a hard coating. [Figure 5] FIG. 1 is a schematic diagram illustrating an example of a hard coating deposition apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the basic configuration of the embodiment will be described. FIG. 1 is a schematic cross-sectional view illustrating a first basic configuration. FIG. 2 is a schematic cross-sectional view illustrating a second basic configuration. FIGS. 3(A) and 3(B) are diagrams illustrating a third basic configuration, with the left diagram being a schematic cross-sectional view and the right diagram being a graph showing the atomic ratio of each composition in the film thickness direction. In the graph in FIG. 3, the vertical axis represents film thickness and the horizontal axis represents atomic ratio (arbitrary unit). FIG. 4 is a schematic cross-sectional view illustrating the third basic configuration. Note that the film thickness ratios of each layer in the schematic cross-sectional views in FIGS. 1 to 4 are merely examples, and the film thickness ratios of each film constituting each basic configuration are not limited to those shown in FIGS. 1 to 4.

[0021] [Overview of the first basic configuration] As shown in FIG. 1, the first basic structure of the hard coating has an abrasion-resistant layer 3 formed on a substrate 1 and an adhesion-resistant layer 4 formed on the abrasion-resistant layer 3. The adhesion-resistant layer 4 is formed of a film having a lower hardness value than the abrasion-resistant layer 3. The abrasion-resistant layer 3 has a composition of (Al,Ti,Cr)N, and the adhesion-resistant layer 4 has a composition of (Al,Ti,Cr)CN. The adhesion-resistant layer 4 also has a composition of (Al 1-y-z Ti y Cr z ) (C 1-a N a ) When expressed as <y≦0.45、0<z≦0.5 、0.6≦a≦0.9 (However, y, z 、a (All of the atomic ratios indicate atomic ratios.)

[0022] When the hard coating of the first basic configuration is applied to, for example, a die for press working or a cutting tool for machining, the adhesion-resistant layer 4 comes into contact with the workpiece during processing and is subjected primarily to high-temperature sliding and pressure, resulting in wear and high-temperature oxidation. Here, the adhesion-resistant layer 4 made of (Al,Ti,Cr)CN has extremely low friction, high sliding properties, and excellent adhesion resistance. Furthermore, the wear-resistant layer 3 made of (Al,Ti,Cr)N has extremely excellent wear resistance and oxidation resistance. Therefore, the hard coating of the first basic configuration has extremely high durability throughout the hard coating.

[0023] Furthermore, the adhesion-resistant layer 4 made of (Al,Ti,Cr)CN has extremely excellent low friction, high sliding properties, and adhesion resistance, and is formed from a film with a lower film hardness value than the wear-resistant layer 3. Therefore, when the adhesion-resistant layer 4 comes into contact with the workpiece during machining, peeling of the adhesion-resistant layer 4 is prevented, while allowing the adhesion-resistant layer 4 to wear down little by little. This enables the hard coating of the first basic configuration to have a longer life.

[0024] Furthermore, even if the Al and / or Ti in the adhesion-resistant layer 4 is eluted from the adhesion-resistant layer 4 due to a chemical reaction such as welding when the adhesion-resistant layer 4 is subjected to high-temperature oxidation due to sliding contact with the workpiece during machining, the Al and / or Ti is replenished from the wear-resistant layer 3 below the adhesion-resistant layer 4. Therefore, with the hard coating of the first basic configuration, even if the adhesion-resistant layer 4 is subjected to sliding contact and oxidation, changes in the composition of the adhesion-resistant layer 4 are suppressed, and its durability is maintained.

[0025] Furthermore, the adhesion-resistant layer 4 made of (Al,Ti,Cr)CN and the wear-resistant layer 3 made of (Al,Ti,Cr)N have the same constituent elements except for carbon and nitrogen, so good adhesion can be achieved between the adhesion-resistant layer 4 and the wear-resistant layer 3.

[0026] Therefore, the hard coating of the first basic configuration extends the life of the hard coating, and provides a long-life hard coating with low friction, high sliding properties, excellent welding resistance, wear resistance, heat resistance, adhesion, etc. Furthermore, the hard coating of the first basic configuration can significantly improve the processing performance of press die processing, cutting processing, etc.

[0027] [Outline of the second basic configuration] As shown in Figure 2, the second basic structure of the hard coating has a lower layer 2 formed on a substrate 1, a wear-resistant layer 3 formed on the lower layer 2, and an adhesion-resistant layer 4 formed on the wear-resistant layer 3. The lower layer 2 has a composition of (Ti,Al)N, the wear-resistant layer 3 has a composition of (Al,Ti,Cr)N, and the adhesion-resistant layer 4 has a composition of (Al,Ti,Cr)CN. The adhesion-resistant layer 4 is made of a film with a lower film hardness value than the wear-resistant layer 3.

[0028] Compared to the hard coating of the first basic configuration, the hard coating of the second basic configuration has a lower layer 2 composed of (Ti,Al)N between the substrate 1 and the wear-resistant layer 3. The lower layer 2 composed of (Ti,Al)N improves the adhesion between the substrate 1 and the wear-resistant layer 3, and can maintain and stabilize the toughness of the hard coating of the second basic configuration.

[0029] [Outline of the 3rd basic configuration] As shown in Figures 3(A), (B) and 4, the third basic structure of the hard coating has a lower layer 2 formed on a substrate 1, a wear-resistant layer 3 formed on the lower layer 2, and an adhesion-resistant layer 4 formed on the wear-resistant layer 3. The lower layer 2 has a composition of (Ti,Al)N, the wear-resistant layer 3 has a composition of (Al,Ti,Cr)N, and the adhesion-resistant layer 4 has a composition of (Al,Ti,Cr)CN. The lower layer 2 has a lower hardness value than the wear-resistant layer 3.

[0030] The wear-resistant layer 3 includes an alternating layer 3c in which first laminated films 3a having a composition of (Al,Ti,Cr)N and second laminated films 3b having a composition of (Al,Ti)N are alternately laminated. The wear-resistant layer 3 further includes a third laminated film 3d having a composition of (Al,Ti,Cr)N and a thickness greater than that of the first laminated film 3a and the second laminated film 3b, located directly above the alternating layer 3c and directly below the adhesion-resistant layer 4.

[0031] In the alternating layers 3c of the wear-resistant layer 3, the atomic ratios of Al and Ti in the film thickness direction change from the lower layer 2 side toward the third stacked film 3d side. Specifically, the atomic ratios of Al and Ti in the film thickness direction of the alternating layers 3c change from the lower layer 2 side toward the third stacked film 3d side (adhesion-resistant layer 4 side) so as to approach the atomic ratios of Al and Ti in the adhesion-resistant layer 4. Furthermore, in the wear-resistant layer 3, the atomic ratio of Cr in the film thickness direction increases toward the third stacked film 3d side.

[0032] The hard coating of the third basic configuration has an anti-adhesion layer 4 made of (Al,Ti,Cr)CN and an abrasion-resistant layer 3 made of (Al,Ti,Cr)N, and therefore, like the hard coatings of the first and second basic configurations, a hard coating is obtained that has a long life and excellent low friction, high sliding properties, adhesion resistance, abrasion resistance, heat resistance, and adhesion.

[0033] Furthermore, because the atomic ratios of Al, Ti, and Cr in the alternating layers 3c of the wear-resistant layer 3 change in the film thickness direction from the lower layer 2 side toward the third laminated film 3d side as described above, the adhesion strength at the interface between the substrate 1, lower layer 2, third laminated film 3d, and adhesion-resistant layer 4 can be stabilized. Therefore, the hard coating having the third basic configuration can more effectively exhibit the toughness required for the lower layer 2, the wear resistance and heat resistance required for the third laminated film 3d, and the low friction, high sliding properties, and adhesion resistance required for the adhesion-resistant layer 4. As a result, the hard coating having the third basic configuration can exhibit excellent low friction, high sliding properties, adhesion resistance, wear resistance, heat resistance, and durability.

[0034] The alternating layers 3c of the wear-resistant layer 3, whose composition varies in the film thickness direction, can be formed, for example, by using multiple targets by arc ion plating or reactive sputtering, alternately stacking films formed by those targets, and varying the film thickness of the film formed by at least one of the targets between the lower layer and the upper layer.

[0035] [Modification of the third basic configuration] In the third basic structure of the hard coating, the lower layer 2 has a composition of (Ti 1-xAl x ) It consists of N and satisfies 0.4 ≦ x ≦ 0.7 (where x is the atomic ratio). The anti - adhesion layer 4 has a composition of (Al 1-y-z Ti y Cr z )(C 1-a N a ) and satisfies 0 < y ≦ 0.45, 0 < z ≦ 0.5, 0.6 ≦ a ≦ 0.9 (where y, z, and a all represent atomic ratios).

[0036] The wear - resistant layer 3 has an alternating layer 3c in which a first laminated film 3a with a composition of (Al, Ti, Cr)N and a second laminated film 3b with a composition of (Al, Ti)N are alternately laminated, and a third laminated film 3d formed immediately above the alternating layer 3c and immediately below the anti - adhesion layer 4. The third laminated film 3d has a composition of (Al 1-y-z Ti y Cr z )N and satisfies 0 < y ≦ 0.45, 0 < z ≦ 0.5 (where y and z both represent atomic ratios). First laminated film 3a has the same composition as the third laminated film 3d.

[0037] The first laminated film 3a, the third laminated film 3d, and the anti - adhesion layer 4 are formed by an arc ion plating method using the same target. The anti - adhesion layer 4 is formed of a film having a smaller film hardness value compared to the wear - resistant layer 3.

[0038] Since the hard film of the third basic configuration includes an anti - adhesion layer 4 with a composition of (Al, Ti, Cr)CN and a wear - resistant layer 3 with a composition of (Al, Ti, Cr)N, similar to the above - mentioned first basic configuration and second basic configuration, a hard film excellent in long life, low friction and high sliding characteristics, anti - welding property, wear resistance, heat resistance, and adhesion can be obtained.

[0039] Furthermore, the anti - adhesion layer 4 has a composition of (Al 1-y-z Ti y Cr z )(C 1-a N a) When expressed as 0 < y ≤ 0.45, 0 < z ≤ 0.5, and 0.6 ≤ a ≤ 0.9, it exhibits an excellent low friction coefficient not only at room temperature but also at high temperatures, and can exhibit excellent low friction and high sliding characteristics and anti-welding properties even in harsher usage environments. Here, it is preferable that 0.2 ≤ y ≤ 0.3, it is preferable that 0.3 ≤ z ≤ 0.5, and it is preferable that 0.65 ≤ a ≤ 0.85.

[0040] Also, the third laminated film 3d of the wear-resistant layer 3 has a composition of (Al 1-y-z Ti y Cr z )N. When expressed as such, since 0 < y ≤ 0.45 and 0 < z ≤ 0.5 are satisfied, it exhibits excellent hardness and Young's modulus not only at room temperature but also at high temperatures, and can exhibit excellent wear resistance even in harsher usage environments. Here, it is preferable that 0.2 ≤ y ≤ 0.3, and it is preferable that 0.3 ≤ z ≤ 0.5.

[0041] Also, the lower layer 2 has a composition of (Ti 1-x Al x )N. When expressed as such, since 0.4 ≤ x ≤ 0.7 is satisfied, it can exhibit excellent wear resistance, heat resistance, and anti-defect properties. Here, it is preferable that 0.5 ≤ x ≤ 0.67.

[0042] Furthermore, the anti-welding layer 4 and the third laminated film 3d are formed by an arc ion plating method using the same target, and their compositions are the same except for carbon and nitrogen. Therefore, the hard film of the third basic structure can obtain extremely good adhesion between the anti-welding layer 4 and the third laminated film 3d.

[0043] Furthermore, the wear-resistant layer 3 includes a first laminated film 3a having the same composition as the third laminated film 3d and the lower layer 2 andSince the hard coating is formed by alternately laminating the first and second laminated films 3b of the same composition, it is possible to alleviate residual stress between the lower layer 2 and the third laminated film 3d and improve adhesion. As a result, the hard coating of the third basic configuration can maintain and stabilize its toughness, and can demonstrate excellent properties without being broken even in usage environments where strong impacts can easily cause damage or chipping of the hard coating.

[0044] In the hard coating of the third basic configuration, the alternating layers 3c of the wear-resistant layer 3 have an average composition of (Al, Ti, Cr)N when viewed as a whole. However, the wear-resistant layer 3 of the third basic configuration is not limited to this, and may include, for example, a film (layer) having a different composition from the lower layer 2 and the third laminated film 3d.

[0045] In the third basic configuration, the alternating layers 3c of the wear-resistant layer 3 may have varying atomic ratios of Al, Ti, and Cr in the film thickness direction, similar to the alternating layers 3c of the wear-resistant layer 3 of the third basic configuration. When the Al atomic ratio of the lower layer 2 and the Al atomic ratio of the third laminated film 3d are the same, the Al atomic ratio of the wear-resistant layer 3 becomes uniform and does not change in the film thickness direction.

[0046] 3(A), for example, the atomic ratio of Al in the alternating layers 3c of the wear-resistant layer 3 may increase toward the third stacked film 3d (adhesion-resistant layer 4), while the atomic ratio of Ti may decrease toward the third stacked film 3d. In this way, in a configuration in which the atomic ratio of Al in the third stacked film 3d is larger than the atomic ratio of Al in the lower layer 2 and the atomic ratio of Ti in the third stacked film 3d is smaller than the atomic ratio of Ti in the lower layer 2, the atomic ratios of Al and Ti in the thickness direction of the alternating layers 3c can be changed from the lower layer 2 side toward the third stacked film 3d side to approach the atomic ratios of Al and Ti in the adhesion-resistant layer 4.

[0047] The alternating layer 3c may have a larger increase in the atomic ratio of Al in the half adjacent to the third stacked film 3d than in the half adjacent to the lower layer 2. The alternating layer 3c may also have a larger decrease in the atomic ratio of Ti in the half adjacent to the third stacked film 3d than in the half adjacent to the lower layer 2. This allows the wear-resistant layer 3 to exhibit superior heat resistance and wear resistance by increasing the content of elements that exhibit these properties on the third stacked film 3d side, where these properties are more important. Furthermore, by making the composition of the alternating layer 3c near the interface on the third stacked film 3d side closer to that of the third stacked film 3d, the wear-resistant layer 3 can achieve excellent interlayer adhesion between the alternating layer 3c and the third stacked film 3d. When concentrating a necessary element, by continuously changing the amount of the element rather than intermittently changing the amount of the element, the toughness of the coating can be maintained and stabilized, and the hard coating can exhibit excellent properties without being destroyed even in a usage environment where the hard coating is subject to large impacts and is prone to chipping or damage.

[0048] The alternating layers 3c of the wear-resistant layer 3 may have an Al atomic ratio that decreases in the thickness direction from the lower layer 2 toward the third stacked film 3d (see FIG. 3(B)), or may have a uniform Al atomic ratio in the thickness direction. The alternating layers 3c of the wear-resistant layer 3 may have an Al atomic ratio that increases in the thickness direction from the lower layer 2 toward the third stacked film 3d, or may have a uniform Ti atomic ratio in the thickness direction.

[0049] In the third basic configuration, the alternating layers 3c of the wear-resistant layer 3 may have a larger increase rate of the atomic ratio of Cr in the half of the layer facing the third laminate film 3d than in the half of the layer facing the lower layer 2. This allows the effect of Cr, which maintains mechanical properties at high temperatures, to be exerted closer to the surface of the hard coating, thereby providing excellent hardness and Young's modulus even at high temperatures and excellent wear resistance even in harsher usage environments.

[0050] The basic configuration and the configurations described in the modified examples (notes, etc.) may be combined, and additions, omissions, substitutions, and other modifications of the configurations are possible.

[0051] [Example] Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the configuration of the hard coating of this embodiment will be described with reference to Fig. 3(A). However, this embodiment is not limited to the third basic configuration.

[0052] As shown in FIG. 3(A), the lower layer 2 is made of (Ti 1-x Al x )N and is formed on the substrate 1 to a thickness of 0.5 to 8 μm, where x is an atomic ratio and 0.4≦x≦0.7.

[0053] The anti-adhesion layer 4 is made of (Al 1-y-z Ti y Cr z )(C 1-a N a ) and the thickness is 0.5 to 8 μm. <y≦0.45、0<z≦0.5、0.6≦a≦0.9である。

[0054] The third laminated film 3d is (Al 1-y-z Ti y Cr z )N and has a thickness of 0.5 to 8 μm. Here, y and z are atomic ratios, and 0 <y≦0.45、0<z≦0.5である。

[0055] The alternating layer 3c of the abrasion-resistant layer 3 is formed between the lower layer 2 and the third stacked film 3d, with a thickness of 0.5 to 5 μm. The alternating layer 3c has a composition between the composition of the lower layer 2 and the composition of the third stacked film 3d. Preferably, the alternating layer 3c is a film formed by alternately stacking a first stacked film 3a having the same composition as the third stacked film 3d and a second stacked film 3b having the same composition as the lower layer 2, with a stacking period of 1 to 100 nm. Note that a composition between the composition of the lower layer 2 and the composition of the third stacked film 3d means that the atomic ratio of each component is a value between the composition of the lower layer 2 and the composition of the third stacked film 3d.

[0056] Next, a method for forming such a hard coating will be described. Fig. 5(A) is a plan view showing a cathode arc ion plating film formation apparatus used to form the hard coating of this example, and Fig. 5(B) is a front view. In this embodiment, two types of films are formed on the substrate by arc ion plating using two cathode electrodes.

[0057] The chamber 10 can be evacuated to a vacuum, and furthermore, a reaction gas such as Ar gas or N2 gas can be introduced into the chamber 10. By introducing the reaction gas under vacuum evacuation, the chamber 10 can be filled with the reaction gas under a predetermined reduced pressure.

[0058] A table 21 is supported on a rotation shaft 36 extending vertically within the chamber 10. The table 21 is rotated via the rotation shaft 36 by an appropriate drive source (not shown). On table 21, rotation shafts 37, 38, 39, and 40 extending vertically are arranged at four equally spaced positions on a circle centered on rotation shaft 36. Rotation shafts 37 to 40 are rotated by planetary gears attached to rotation shaft 36 as a sun gear. A plurality of substrates 22, 23, 24, and 25 are attached to each of rotation shafts 37 to 40. Substrates 22 to 25 rotate about rotation shafts 37 to 40 and revolve around rotation shaft 36.

[0059] A heater 11, a first cathode electrode 12 as a first evaporation source, a third cathode electrode 13 as a bombardment cleaning source, and a second cathode electrode 14 as a second evaporation source are arranged at approximately equal intervals in a counterclockwise direction in a plan view around the table 21. The heater 11 heats the substrates 22 to 25.

[0060] One of the two films formed on the substrates 22 to 25, the first cathode electrode 12 for forming the film, and the second cathode electrode 14 for forming the other film are installed at positions facing each other with the rotation axis 36 interposed therebetween. And a third cathode electrode 13 for bombardment cleaning is disposed between the first cathode electrode 12 and the second cathode electrode 14. As the third cathode electrode 13, ordinary metal Ti is used.

[0061] Near the lower ends of the cathode electrodes 12, 13, and 14, anode electrodes 15, 16, and 17 are respectively disposed. A first arc power source 31 is connected between the first anode electrode 15 and the first cathode electrode 12 via a conducting wire 34. A second arc power source 32 is connected between the second anode electrode 17 and the second cathode electrode 14 via a conducting wire 35. Also, an arc power source (not shown) is connected between the third cathode electrode 13 and the third anode electrode 16. A bias power source 33 for applying a negative bias voltage to the substrates 22 to 25 is connected to the table 21. Note that the chamber 10 is provided with an inlet for the process gas and an exhaust port (both not shown) for vacuum exhaust.

[0062] Next, the operation of the cathode arc ion plating film forming apparatus configured as described above will be described. For example, a TiAl target is installed on the first cathode electrode 12 as the first evaporation source, and an AlTiCr target is installed on the second cathode electrode 14 as the second evaporation source. Here, when the TiAl target is represented by the composition Ti 1-x Al x it satisfies 0.4 ≦ x ≦ 0.7 (where x represents the atomic ratio). Also, when the AlTiCr target is represented by the composition Al 1-y-z Ti y Cr z it satisfies 0 < y ≦ 0.45, 0 < z ≦ 0.5 (where y, z, and a all represent atomic ratios).

[0063] The substrates 22-25, which have been dried after chemical cleaning, are placed on the rotating shafts 37-40. The substrates 22-25 are, for example, SKD11 steel plates each having a size of 25 mm x 25 mm and a thickness of 7 mm. The substrates are hardened materials with a hardness of 60 HRC. The surfaces of the substrates are polished to Ra = 0.01-0.02 μm.

[0064] The chamber 10 is filled with, for example, 1×10 -3 The chamber is evacuated to a base pressure of 0.1 Pa, and the table 21 is rotated, and the rotary shafts 37-40 on the table 21 are rotated. As a result, the substrates 22-25 held by the rotary shafts 37-40 revolve around the table 21 and rotate on their axes on the table 21. Then, electricity is applied to the heater 11 to heat the substrates 22-25 on the table 21 to a temperature of, for example, 450°C. As the substrates 22-25 rotate and revolve, they are uniformly heated by the heater 11.

[0065] The bombardment process then begins. Ar gas is introduced into the chamber 10, and a bias voltage of -300 V is applied at a substrate temperature of 450°C. These conditions are maintained for 60 minutes while the table 21 rotates at, for example, 1 rpm. Alternatively, Ti, Cr, or TiAl is placed on the third cathode electrode 13 as a bombardment metal. In the high-temperature vacuum, a bias voltage of -1000 V is applied to the table 21 by the bias power supply 33, and a current of 100 A is applied to the third cathode electrode 13 by the arc power supply. This ion bombardment process cleans the surfaces of the substrates 22-25.

[0066] The process then moves to the vapor deposition step. First, N2 gas is introduced into the chamber 10. Next, a cathode current of, for example, 100 A is supplied to the first cathode electrode 12 on which the TiAl target is placed. At this time, a bias voltage of, for example, -50 V is applied to the substrates 22-25 by the bias power supply 33. As a result, a lower layer 2 made of a (Ti,Al)N vapor deposition film is formed on the substrates 22-25. For example, the lower layer 2 is formed to a thickness of 1.5 μm.

[0067] While continuing to supply a cathode current to the first cathode electrode 12 and applying a bias voltage to the substrates 22 to 25, a cathode current of, for example, 120 A is supplied to the second cathode electrode . In this way, by simultaneously discharging two types of opposing targets while rotating the substrates 22-25 on which the lower layer 2 is formed, a first stacked film 3a made of (Al,Ti,Cr)N films and a second stacked film 3b made of (Ti,Al)N films are alternately formed on the lower layer 2, and an alternating layer 3c is formed as a whole, as shown in Fig. 4. For example, the alternating layer 3c is formed to a thickness of 1.5 µm.

[0068] While continuing to apply the bias voltage to the substrates 22-25, the cathode current to the first cathode electrode 12 is set to 0, and the cathode current to the second cathode electrode 14 is set to, for example, 140 A. As a result, a third stacked film 3d made of an (Al, Ti, Cr)N film is formed on the alternating layer 3c. For example, the third stacked film 3d is formed to a thickness of 1 μm. As a result, the wear-resistant layer 3 is formed.

[0069] While continuing to supply a cathode current to the second cathode electrode 14 and apply a bias voltage to the substrates 22-25, a mixed gas of N2 gas and CH4 is introduced into the chamber 10. As a result, an adhesion-resistant layer 4 made of an (Al,Ti,Cr)CN film is formed on the wear-resistant layer 3. For example, the adhesion-resistant layer 4 is formed to a thickness of 1 μm.

[0070] In the arc ion plating of this embodiment, a negative voltage is applied to the cathode electrodes 12 and 14, generating an arc discharge between the cathode electrodes 12 and 14 and the anode electrodes 15 and 16. This arc discharge forms an arc spot on the surface of the TiAl target placed on the first cathode electrode 12 or on the surface of the AlTiCr target placed on the second cathode electrode 14, and moves randomly across the target surface. The energy of the arc current concentrated at the arc spot causes the target material to instantly evaporate, turning into metal ions (positive ions) that are released into the vacuum. The released metal ions are deposited on the surfaces of substrates 22-25, which are the objects to be coated (e.g., molds, cutting tools, machine parts), to form a film. At this time, because a negative bias voltage is applied to the substrates 22-25, the metal ions (positive ions) in the vacuum are accelerated by electrical attraction toward the substrates 22-25 and collide with the surfaces of the substrates 22-25 with high energy together with reactive gas particles. As a result, the hard coating is formed in close contact with the surface of the substrates 22 to 25, and a dense hard coating is produced.

[0071] By changing the magnitude of the arc current supplied to the cathode electrodes 12, 14 and the magnitude of the bias voltage applied to the substrates 22-25, the amount of metal ions emitted from the target and the speed at which the metal ions collide with the surfaces of the substrates 22-25 can be changed.

[0072] For example, in the process of forming the alternating layers 3c, the thicknesses of the first laminated film 3a and the second laminated film 3b can be made different by varying the magnitude of the arc current between the first cathode electrode 12 and the second cathode electrode 14. This allows the average composition of the two-layer film consisting of one adjacent first laminated film 3a and one adjacent second laminated film 3b to be designed to a desired composition between the composition of the TiAl target and the composition of the AlTiCr target.

[0073] Furthermore, in the process of forming the alternating layers 3c, the magnitude of the arc current supplied to the cathode electrodes 12, 14 and the magnitude of the bias voltage applied to the substrates 22-25 can be changed between the lower side (lower layer 2 side) and the upper side (adhesion-resistant layer 4 side) of the alternating layers 3c to form alternating layers 3c in which the atomic ratio of Al, Ti, and Cr varies in the film thickness direction. For example, by increasing the magnitude of the arc current supplied to the second cathode electrode 14 holding the AlTiCr target in a stepwise or continuous manner during deposition of the alternating layers 3c, it is possible to form alternating layers 3c having a composition in which the atomic ratio of Cr in the film thickness direction increases toward the third stacked film 3d side (adhesion-resistant layer 4 side).

[0074] Several of the hard coatings obtained in this way exhibited properties such as a Vickers hardness of approximately 2500 Hv (an example of a coating hardness value), an oxidation resistance temperature of approximately 700°C, and a friction coefficient of approximately 0.40.Compared to conventional (Ti,Al)N and (Al,Ti,Cr)N coatings, they exhibited excellent low friction, high sliding properties, and welding resistance while maintaining excellent wear resistance and heat resistance.

[0075] As a comparative example, a hard coating was formed on a substrate 1, with an abrasion-resistant layer 3 having a lower layer 2, alternating layers 3c, and a third laminate film 3d, and then no adhesion-resistant layer 4 was formed. The hard coating exhibited a Vickers hardness of approximately 3500 Hv, an oxidation-resistant temperature of approximately 1000°C, and a friction coefficient of approximately 0.60. These results showed that the adhesion-resistant layer 4 had a lower coating hardness value than the abrasion-resistant layer 3.

[0076] Although the embodiments have been described above, the present invention is not limited to the above-described embodiments and can be embodied in various forms. The configuration of each part is not limited to the illustrated embodiments, and various modifications are possible without departing from the spirit of the present invention. Furthermore, the configurations described in the above-described embodiments and variations (such as the above-described supplementary notes) may be combined, and additions, omissions, substitutions, and other modifications of the configurations are possible, without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the above-described embodiments.

[0077] For example, the composition of the wear-resistant layer 3 is not limited to (Al,Ti,Cr)N. The hard coating of the present invention is not particularly limited to the composition of the wear-resistant layer, as long as the wear-resistant layer formed directly below the adhesion-resistant layer has a greater coating hardness value than the adhesion-resistant layer. Furthermore, the composition of the lower layer 2 formed between the substrate 1 and the wear-resistant layer 3 is not limited to a film consisting of (Al,Ti)N, and may be any film that can improve the adhesion between the substrate 1 and the wear-resistant layer 3.

[0078] Furthermore, in the above first to third basic configurations, the wear-resistant layer 3 may be formed only of the alternating layers 3c (a configuration without the third stacked film 3d), or may be formed of a single layer film (for example, a configuration formed only of the third stacked film 3d). [Explanation of symbols]

[0079] 1 base material, 2 lower layer, 3 wear-resistant layer, 3a first laminated film, 3b second laminated film, 3c alternating layers, 3d third laminated film, 4 anti-adhesion layer

Claims

1. A hard coating formed on a substrate, an abrasion-resistant layer formed on the substrate; an adhesion-resistant layer formed on the wear-resistant layer, The anti-adhesion layer has a composition of (Al 1-y-z Ti y Cr z ) (C 1-a N a ), the range of y≦0.45, 0<z≦0.5, and 0.6≦a≦0.9 (where y, z, and a each represent an atomic ratio) is satisfied, and the coating hardness value is smaller than that of the abrasion-resistant layer. Hard coating.

2. The wear-resistant layer has a composition of (Al, Ti, Cr)N. The hard coating according to claim 1 .

3. a lower layer having a composition of (Al, Ti)N is formed between the substrate and the wear-resistant layer; The hard coating according to claim 2.

4. the abrasion-resistant layer includes alternating layers in which a first laminate film having a composition of (Al, Ti, Cr)N and a second laminate film having a composition of (Al, Ti)N are alternately laminated; The hard coating according to claim 3.

5. the abrasion-resistant layer includes a third stacked film, which is formed of (Al, Ti, Cr)N and has a thickness greater than that of the first stacked film and the second stacked film, and is disposed directly above the alternating layers and directly below the adhesion-resistant layer. The hard coating according to claim 4.

6. the first stacked film, the third stacked film, and the adhesion-resistant layer have the same atomic ratio of (Al, Ti, Cr); The hard coating according to claim 5.

7. the atomic ratio of (Al, Ti) in the lower layer and the second stacked film is the same; The hard coating according to claim 4.

8. The lower layer has a composition of (Ti 1-x Al x ) N, satisfies 0.4≦x≦0.7 (where x represents an atomic ratio); The hard coating according to claim 7.

9. In the alternate layers of the wear-resistant layer, the atomic ratio of Al and the atomic ratio of Ti in the thickness direction change from the lower layer side toward the adhesion-resistant layer side, and the atomic ratio of Cr in the thickness direction increases toward the adhesion-resistant layer side. The hard coating according to any one of claims 4 to 8.

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