Sliding member, method for manufacturing the same, and coated film

Abstract

The present invention provides a sliding component and a coating film that exhibits excellent resistance to cracking and wear, as well as excellent resistance to peeling (adhesion) and achieves reduced friction. The present invention provides a sliding component (10) having a coating film (1) on a sliding surface (16) on a substrate (11). The coating film (1) has: a stacked portion (1A) having repeating units stacked in the thickness direction (Y), the repeating units comprising a black hard carbon layer (B) that is relatively black when the cross-section is observed using a bright-field TEM image and a white hard carbon layer (W) that is relatively white; and a surface portion (1C) consisting of a white hard carbon layer disposed on the stacked portion (1A). The black hard carbon layer has a Vickers hardness in the range of 700 to 1600 HV, the white hard carbon layer is higher than the adjacent black hard carbon layer and is in the range of 1200 to 2200 HV, and the surface portion is lower than the white hard carbon layer and is in the range of 800 to 1200 HV.

Description

Technical Field

[0001] This invention relates to sliding components, methods of manufacturing the same, and coating films. More specifically, this invention relates to a sliding component exhibiting excellent chipping resistance, abrasion resistance, peel resistance (adhesion), and reduced friction, a method of manufacturing the same, and a coating film. Background Technology

[0002] In recent years, research on hard carbon layers has flourished in various industrial sectors, particularly the automotive industry, for use as coatings on the surfaces of sliding components such as engine substrates and other mechanical substrates. Hard carbon layers are commonly referred to by various names, including diamond-like carbon (DLC) layers, amorphous carbon layers, i-carbon layers, and diamond-like carbon layers. Structurally, such hard carbon layers are classified as amorphous.

[0003] It is believed that the hard carbon layer contains single bonds visible in diamond crystals and double bonds visible in graphite crystals. In addition to the high hardness, high wear resistance, and excellent chemical stability of diamond crystals, this hard carbon layer also possesses the low hardness, high lubricity, and excellent material-material running-in properties of graphite crystals. Furthermore, this hard carbon layer is amorphous, thus exhibiting excellent flatness and low friction (i.e., a small coefficient of friction) in direct contact with the workpiece material, as well as excellent material-material running-in properties.

[0004] In the sliding surfaces of sliding components, chipping resistance and wear resistance are important properties. However, since chipping resistance and wear resistance are mutually exclusive, it is difficult to create a coating that satisfies these trade-offs. As a means to address this, studies have been conducted on creating a low-hardness hard carbon layer or a mixed layer of low-hardness and high-hardness hard carbon to balance chipping resistance and wear resistance.

[0005] However, current research on achieving a balance between crack resistance and wear resistance is still insufficient. This is especially true for coatings applied to sliding components subjected to high loads, such as piston rings, which require not only crack resistance and wear resistance but also low friction and peel resistance; however, improvements in these properties are still inadequate. Various technologies have been proposed in recent years to address these technical challenges.

[0006] For example, Patent Document 1 proposes a technology that can form a durable, thick hard carbon layer using PVD, while also achieving good chipping and abrasion resistance, and improving low friction and peel resistance. This technology relates to a coating film applied to the surface of a substrate, in which, when the cross-section is observed using a bright-field TEM image, white hard carbon layers (represented by white) and black hard carbon layers (represented by black) are alternately stacked in the thickness direction, resulting in a total film thickness exceeding 1 μm and less than 50 μm. The white hard carbon layers have fan-shaped growth regions in the thickness direction.

[0007] Furthermore, Patent Document 2 discloses a sliding component and its coating film, which exhibits constant and stable resistance to chipping and abrasion, as well as excellent peel resistance (adhesion). This technology relates to a sliding component having a coating film composed of a hard carbon layer on its sliding surface. The coating film, when viewed in cross-section using a bright-field TEM image, has a thickness ranging from 1 μm to 50 μm due to the stacking of repeating units in the thickness direction. Each repeating unit comprises a black hard carbon layer (represented by black) and a white hard carbon layer (represented by white). The coating film has: an inclined region disposed on the substrate side, where the thickness of the white hard carbon layer in the repeating unit gradually increases in the thickness direction; and a homogeneous region disposed on the surface side, where the thickness of the white hard carbon layer in the repeating unit is the same or approximately the same in the thickness direction. The inclined region has a V-shaped or radial growth pattern in the thickness direction, while the homogeneous region does not have a V-shaped or radial growth pattern in the thickness direction.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: WO2017 / 104822A1

[0011] Patent Document 2: WO2018 / 235750A1 Summary of the Invention

[0012] The technical problem that the invention aims to solve

[0013] The coating film of sliding components requires properties such as crack resistance, wear resistance, and low friction, with a desire to further reduce friction (friction loss). Hard carbon layers are anticipated as a raw material capable of achieving low friction. The inventors have conducted research on reducing friction, particularly on surface layers that maintain good contact with the target component during the initial sliding stage.

[0014] The purpose of this invention is to provide a new sliding component, its manufacturing method, and a coating film that exhibits excellent resistance to cracking and wear, as well as excellent peel resistance (adhesion) and reduced friction.

[0015] means of solving technical problems

[0016] (1) The sliding component of the present invention is a sliding component having a coating film on a sliding surface on a substrate, wherein the coating film has: a stacked portion formed by stacking repeating units in the thickness direction, the repeating unit comprising a black hard carbon layer that is relatively black when the cross-section is observed using a bright-field TEM image and a white hard carbon layer that is relatively white; and a surface portion composed of a white hard carbon layer disposed on the stacked portion, wherein the Vickers hardness of the black hard carbon layer is in the range of 700 to 1600 HV, the Vickers hardness of the white hard carbon layer is higher than that of the adjacent black hard carbon layer and is in the range of 1200 to 2200 HV, and the Vickers hardness of the surface portion is lower than that of the white hard carbon layer and is in the range of 800 to 1200 HV.

[0017] Similar to existing technologies, in the laminated portion, the relatively black hard carbon layer is high-density and [sp 2 / (sp 2 +sp 3 The ratio is small, and the strength is excellent. The relatively white, hard carbon layer has a low density and [sp] 2 / (sp 2 +sp 3 The material exhibits a high density, low friction, and excellent resistance to chipping. However, the laminated portion of this invention differs from existing technologies in that, among adjacent black and white hard carbon layers, the hardness of the white hard carbon layer is higher than that of the black hard carbon layer. By depositing this laminate of hard carbon layers, i.e., the coating film, on the sliding surface, a sliding component with excellent resistance to chipping, wear, and peeling (adhesion) can be manufactured based on the laminated effect of the hard carbon layers with different properties. Furthermore, in this invention, the surface layer composed of white hard carbon layers has a lower hardness range than that of the black hard carbon layers, which reduces friction when in contact with the target component in the initial stage of sliding.

[0018] In the sliding component of the present invention, the adjacent black hard carbon layer and the white hard carbon layer [sp 2 / (sp 2 +sp 3 )] compared to the surface layer [sp 2 / (sp 2 +sp 3The ratio is: [the black hard carbon layer < the white hard carbon layer ≤ the surface layer] or [the black hard carbon layer < the surface layer ≤ the white hard carbon layer].

[0019] According to the present invention, regarding the adjacent black hard carbon layers and white hard carbon layers in the laminated portion [sp 2 / (sp 2 +sp 3 Compared to the black hard carbon layer, the white hard carbon layer is larger. Based on the layering effect of these different hard carbon layers, sliding parts with excellent resistance to chipping, wear, and peeling (adhesion) can be manufactured. Furthermore, the surface layer composed of the white hard carbon layer... 2 / (sp 2 +sp 3 The surface layer is larger than the black hard carbon layer and has the same thickness as the white hard carbon layer. This surface layer can reduce friction when in contact with the object component in the initial stage of sliding.

[0020] In the sliding component of the present invention, the thickness of the surface layer is in the range of 0.1 to 1.0 μm, and the thickness of the repeating unit is in the range of 0.2 to 2 μm.

[0021] In the sliding component of the present invention, the black hard carbon layer [sp 2 / (sp 2 +sp 3 The ratio of the white hard carbon layer to the [sp] is in the range of 0.05 to 0.75. 2 / (sp 2 +sp 3 The ratio of [sp] to the black hard carbon layer is greater than that of [sp]. 2 / (sp 2 +sp 3 The ratio of the surface layer to the [sp] value is within the range of 0.20 to 0.80. 2 / (sp 2 +sp 3 The ratio is in the range of 0.20 to 0.80.

[0022] In the sliding component of the present invention, a carbon layer is preferably located directly below the black hard carbon layer and / or directly below the white hard carbon layer.

[0023] In the sliding component of the present invention, when observing the cross section using a bright-field TEM image, a hard carbon substrate film can be disposed between the substrate or an intermediate layer disposed on the substrate and the coating film.

[0024] In the sliding component of the present invention, the sliding component is a piston ring.

[0025] (2) The method for manufacturing the sliding component of the present invention is a method for manufacturing the sliding component of the present invention having a coating film on the sliding surface of a substrate, wherein the coating film has: a stacked portion formed by stacking repeating units in the thickness direction, the repeating unit comprising a black hard carbon layer that is relatively black when the cross-section is observed using a bright-field TEM image and a white hard carbon layer that is relatively white; and a surface portion formed by a white hard carbon layer disposed on the stacked portion, wherein the film-forming temperature of the surface portion is higher than the film-forming temperature of the stacked portion for film formation.

[0026] (3) The coating of the present invention comprises: a stacked portion formed by stacking repeating units in the thickness direction, the repeating unit comprising a black hard carbon layer that is relatively black when the cross-section is observed using a bright-field TEM image and a white hard carbon layer that is relatively white; and a surface portion composed of a white hard carbon layer disposed on the stacked portion, wherein the Vickers hardness of the black hard carbon layer is in the range of 700 to 1600 HV, the Vickers hardness of the white hard carbon layer is higher than that of the adjacent black hard carbon layer and is in the range of 1200 to 2200 HV, and the Vickers hardness of the surface portion is lower than that of the white hard carbon layer and is in the range of 800 to 1200 HV.

[0027] In the coating film of the present invention, the adjacent black hard carbon layer and the white hard carbon layer [sp 2 / (sp 2 +sp 3 )] compared to the surface layer [sp 2 / (sp 2 +sp 3 The ratio is: [the black hard carbon layer < the white hard carbon layer ≤ the surface layer] or [the black hard carbon layer < the surface layer ≤ the white hard carbon layer].

[0028] Invention Effects

[0029] According to the present invention, a new sliding component, its manufacturing method, and the coating film are provided, which exhibit crack resistance and wear resistance, excellent peel resistance (adhesion), and reduced friction, and are particularly suitable as sliding components subjected to high loads, such as piston rings. Attached Figure Description

[0030] [ Figure 1 [Illustrated cross-sectional view] is a schematic cross-sectional view showing an example of a coating film disposed in the sliding component of the present invention.

[0031] [ Figure 2The following are explanatory diagrams illustrating examples of coating films. (A) is an example of a stacked portion consisting of repeated units having a black hard carbon layer B and a white hard carbon layer W on top of it, and a cross-sectional view showing a surface layer disposed thereon. (B) is an example of a stacked portion consisting of repeated units having a white hard carbon layer W and a black hard carbon layer B on top of it, and a cross-sectional view showing a surface layer disposed thereon.

[0032] [ Figure 3 The following is an explanatory diagram illustrating another example of a coating film. (A) is an example of a stacked portion consisting of repeated units having a black hard carbon layer B and a white hard carbon layer W on it, and a cross-sectional shape example having a surface layer thereon. (B) is an example of a stacked portion consisting of repeated units having a white hard carbon layer W and a black hard carbon layer B on it, and a cross-sectional shape example having a surface layer thereon.

[0033] [ Figure 4 [Image ] is a bright-field TEM image of a cross-section representing an instance of the coating membrane.

[0034] [ Figure 5 [Image 1] is a bright-field TEM image showing a cross-section of an example of the surface portion that constitutes the coating.

[0035] [ Figure 6 [Illustrated cross-sectional view] is a schematic cross-sectional view showing an example of a piston ring with a coating.

[0036] [ Figure 7 [Image] is a schematic diagram of the friction and wear test method using the SRV testing machine.

[0037] [ Figure 8 [ ] is a bright-field TEM image of a cross section representing the film formation mode of the carbon layer that constitutes the coating film. Detailed Implementation

[0038] The sliding component, its manufacturing method, and the coating film of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the present invention is not limited to the following description and drawings, but also includes variations within the scope of its intent.

[0039] [Sliding component]

[0040] For example, Figure 6 As shown in the example of a piston ring, the sliding member 10 of the present invention is a sliding member 10 having a covering film 1 on the sliding surface 16. The covering film 1 has: a stacked portion 1A, which consists of repeated units stacked in the thickness direction Y (…). Figure 2 and Figure 3The repeating unit (represented by the symbol *) comprises a black hard carbon layer B, which is relatively black when the cross-section is observed using a bright-field TEM image, and a white hard carbon layer W, which is relatively white; and a surface layer 1C, which is composed of the white hard carbon layer disposed on the stacked portion 1A. Regarding hardness, the Vickers hardness of the black hard carbon layer B is in the range of 700 to 1600 HV, the Vickers hardness of the white hard carbon layer W is higher than that of the adjacent black hard carbon layer B and is in the range of 1200 to 2200 HV, and the Vickers hardness of the surface layer 1C is lower than that of the white hard carbon layer W and is in the range of 800 to 1200 HV.

[0041] Regarding the coating film 1 constituting this sliding component 10, in the laminated portion 1A, as in conventional technology, the relatively black hard carbon layer B is high-density and sp 2 / sp 3 It has a smaller density and superior strength compared to the white, hard carbon layer, which is relatively low in density and sp. 2 / sp 3 It exhibits a high specific gravity, low friction, and excellent chip resistance. However, unlike conventional technologies, the laminated portion 1A has a higher hardness in the white hard carbon layer W than in the adjacent black hard carbon layer B and white hard carbon layer W. By providing the laminate of these hard carbon layers B and W, i.e., the laminated portion 1A, on the sliding surface 16, a sliding component 10 with excellent chip resistance, wear resistance, and peel resistance (adhesion) can be manufactured based on the stacking effect of hard carbon layers with different properties. Furthermore, the surface layer 1C, composed of white hard carbon layers, has a lower hardness range than that of the black hard carbon layer B, which reduces friction when in contact with the target component during the initial sliding phase.

[0042] It should be noted that bright-field TEM images can be obtained by observing the thin-film coating 1, which has been thinned using a focused ion beam (FIB), with an accelerating voltage of, for example, 300 kV using a TEM (transmission electron microscope). The thickness direction Y refers to the direction in which the laminate portion 1A and the surface portion 1C are sequentially stacked on the substrate 11.

[0043] The following details the constituent elements of the sliding component. It should be noted that, while the piston ring is used extensively as an example of a sliding component in the following description, the sliding component of the present invention is not limited to piston rings. Furthermore, [sp...] 2 / (sp 2 +sp 3 )] is simplified to "sp" 2 / sp 3Compare."

[0044] (Substrate)

[0045] like Figure 1 , Figure 2 and Figure 3 As shown, substrate 11 is the component to which the coating film 1 is applied. The substrate 11 is not particularly limited and can include ferrous metals, non-ferrous metals, ceramics, hard composite materials, etc. Examples include carbon steel, alloy steel, hardened steel, high-speed tool steel, cast iron, aluminum alloys, magnesium alloys, and superhard alloys. It should be noted that, considering the film-forming temperature of the coating film 1, a substrate whose properties do not significantly deteriorate at temperatures exceeding 200°C is preferred.

[0046] As the piston ring substrate 11 when the coating film 1 is applied to the piston ring 10, various substrates can be used as the substrate of the piston ring 10, and there is no particular limitation. For example, various steels, stainless steels, casting materials, cast steel materials, etc. can be used. Among them, martensitic stainless steel, chromium manganese steel (SUP9 material), chromium vanadium steel (SUP10 material), silicon chromium steel (SWOSC-V material), etc. can be used. The substrate 11 can have the following characteristics as needed. Figure 1 The base layer 11a is shown. Examples of base layers 11a include base layers that improve the adhesion to the intermediate layer 12 described later, and there is no particular limitation.

[0047] Alternatively, a layer of at least one nitride, carbonitride, or carbide selected from Cr, Ti, Si, and Al can be pre-formed on the piston ring substrate 11 as a base layer 11a. Examples of such compound layers include CrN, TiN, CrAlN, TiC, TiCN, and TiAlSiN. Among these, wear-resistant films (not shown) formed by nitriding treatment, Cr-N type, Cr-BN type, and Ti-N type formed by nitriding treatment are preferred. It should be noted that the piston ring 10 exhibits excellent wear resistance even without such nitriding treatment, Cr-based, or Ti-based wear-resistant films; therefore, the formation of nitriding treatment, Cr-based, or Ti-based wear-resistant films is not a necessary structure.

[0048] The piston ring substrate 11 can also be pretreated as needed. As a pretreatment, surface grinding is preferred to adjust the surface roughness. The adjustment of surface roughness is preferably performed by, for example, grinding the surface of the piston ring substrate 11 with diamond abrasive grains. The piston ring substrate 11 obtained in this way is suitable for: pretreatment before forming the intermediate layer 12 described later, or pretreatment of the base layer 11a, etc., which is pre-formed before forming the intermediate layer 12, etc.

[0049] (Middle layer)

[0050] like Figures 1-3 As shown, the intermediate layer 12 is preferably disposed between the substrate 11 and the coating film 1 as needed. This intermediate layer 12 can further improve the adhesion between the substrate 11 and the coating film 1.

[0051] As the intermediate layer 12, a layer containing at least one or two elements such as Cr, Ti, Si, W, and B can be provided. It should be noted that a base layer 11a containing a compound such as a nitride, carbonitride, or carbide containing at least one or two elements such as Cr, Ti, Si, and Al can also be provided below the intermediate layer 12 (between the substrate 11 and the intermediate layer 12). Examples of such compounds include CrN, TiN, CrAlN, TiC, TiCN, and TiAlSiN. It should be noted that the formation of the base layer 11a, which is provided as needed, can be performed, for example, by placing the substrate 11 in a chamber, creating a vacuum in the chamber, performing preheating, ion cleaning, introducing inert gases such as nitrogen, and then performing vacuum evaporation, ion plating, or other methods.

[0052] As an intermediate layer 12 when the coating film 1 is applied to the piston ring 10, examples include titanium films or chromium films. In this case, the intermediate layer 12 may not be necessary, and its formation is arbitrary. The intermediate layer 12, such as titanium films or chromium films, can be formed by various film formation methods such as vacuum evaporation, sputtering, and ion plating. For example, the piston ring substrate 11 can be placed in the chamber, the chamber can be evacuated, and then preheated, ion cleaned, and an inert gas can be introduced. The thickness of the intermediate layer 12 is not particularly limited, but is preferably in the range of 0.05 μm or more and 2 μm or less. It should be noted that the intermediate layer 12 is preferably formed at least on the outer peripheral sliding surface 16 where the piston ring 10 contacts and slides with the cylinder liner (not shown), but can also be formed on other surfaces, such as the upper surface, lower surface, and inner peripheral surface of the piston ring 10.

[0053] The intermediate layer 12 can be formed directly on the piston ring substrate 11, or it can be formed on the nitrided surface or on the base layer 11a composed of a wear-resistant film. The intermediate layer 12 improves the adhesion between the piston ring substrate 11 and the coating film 1. It should be noted that other layers can be provided between the intermediate layer 12 and the coating film 1 as needed to further improve their adhesion. For example, a hard carbon substrate film with the same or substantially the same composition as the coating film 1 described later can also be formed.

[0054] (Covering film)

[0055] like Figures 2-5As shown, the coating 1 is composed of a stacked portion 1A and a surface portion 1C. The stacked portion 1A has two hard carbon layers (B and W) that are represented in black and white respectively when observing a bright-field TEM image of its cross-section. The black hard carbon layer B and the white hard carbon layer W are stacked to form a repeating unit. Figure 2 and Figure 3 In the image (represented by the symbol *), this repeating unit is stacked in the thickness direction Y to form a stacked portion 1A. The surface layer 1C is a white hard carbon layer disposed on the stacked portion 1A. It should be noted that "relatively" refers to the relative relationship of the tones when observing the cross-section using a bright-field TEM image; the layer that appears black is "black hard carbon layer B", and the layer that appears white is "white hard carbon layer W".

[0056] When the coating film 1 is applied to the piston ring 10, such as Figure 6 As shown, the coating film 1 is formed at least on the outer peripheral sliding surface 16 where the piston ring 10 contacts and slides with the cylinder liner (not shown). Alternatively, it can be formed on other surfaces, such as the upper surface, lower surface, or inner peripheral surface of the piston ring 10.

[0057] (Laminated section)

[0058] like Figure 2 and Figure 3 As shown, the laminate 1A is formed by stacking repeating units of black hard carbon layer B and white hard carbon layer W, and the stacking order is not particularly limited. Figure 2 (A) and Figure 3 As shown in (A), repeating units with a black hard carbon layer B and a white hard carbon layer W deposited on top of it can be stacked, or as shown in... Figure 2 (B) and Figure 3 As shown in (B), a stack of repeating units is formed, with a white hard carbon layer W and a black hard carbon layer B formed on top of it. The repeating units can be... Figure 2 and Figure 3 In any of the arrangements shown, the black hard carbon layer B and the white hard carbon layer W constituting the repeating unit are formed in an adjacent manner. Furthermore, Figure 2 and Figure 3 The difference lies in the layer directly beneath the surface layer 1C. Figure 2 The middle layer is a white, hard carbon layer W. Figure 3 The middle layer is a black, hard carbon layer B.

[0059] Similar to previous technologies, the relatively black hard carbon layer B is high-density and sp 2 / sp 3 It has a smaller density and superior strength compared to the white, hard carbon layer, which is relatively low in density and sp. 2 / sp 3It has a high specific gravity, and exhibits excellent low friction and crack resistance. However, the hardness of the laminated portion 1A constituting the coating film 1 of the present invention differs from that of conventional technologies. Among the adjacent black hard carbon layer B and white hard carbon layer W, the hardness of the white hard carbon layer W is higher than that of the black hard carbon layer B. That is, the black hard carbon layer B has a lower hardness and higher density compared to the adjacent white hard carbon layer W. Conversely, the white hard carbon layer W has a higher hardness and lower density compared to the adjacent black hard carbon layer B.

[0060] Regarding SP 2 / sp 3 The white hard carbon layer W is larger than the black hard carbon layer B. More specifically, the black hard carbon layer B has a lower hardness (sp) compared to the adjacent white hard carbon layer W. 2 / sp 3 Compared to the adjacent black hard carbon layer B, the white hard carbon layer W, with its smaller size and higher density, has a higher hardness. 2 / sp 3 It has a large density and low density. As shown in the experimental results, the laminate 1A, formed by repeating units of such black hard carbon layer B and white hard carbon layer W, can produce a sliding component 10 with excellent crack resistance, wear resistance, and peel resistance (adhesion) based on the laminate effect of hard carbon layers B and W with different properties. Furthermore, sp 2 / sp 3 The ratio is to [sp 2 / (sp 2 +sp 3 The simplified representation is indicated by the "sp" mentioned later. 2 / sp 3 The method described in the "Comparison" section is used for measurement.

[0061] Regarding hardness, the Vickers hardness of the black hard carbon layer B is preferably in the range of 700–1600 HV, more preferably in the range of 750–1200 HV. The Vickers hardness of the white hard carbon layer W is preferably higher than that of the adjacent black hard carbon layer B and is in the range of 1200–2200 HV, more preferably in the range of 1250–1900 HV.

[0062] Regarding SP 2 / sp 3 Compared to the black, hard carbon layer B, sp 2 / sp 3 The preferred ratio is in the range of 0.05 to 0.75. The white, hard carbon layer W has a sp... 2 / sp 3 The preferred sp is greater than that of the black hard carbon layer B. 2 / sp 3The ratio is within the range of 0.20 to 0.80. 2 / sp 3 The smaller, black, hard carbon layer B is due to carbon bonds (sp) represented by diamond. 3 The structure has a relatively large number of bonds, resulting in high density and therefore high hardness. However, in this invention, while the density is high, the hardness is low. On the other hand, sp 2 / sp 3 The larger, white, hard carbon layer W is due to carbon bonds (sp) represented by graphite. 2 The structure has relatively more bonds, resulting in low density and therefore low hardness. However, in this invention, while the density is low, the hardness is high. This is believed to be due to the film-forming process described later. Furthermore, sp 2 / and sp 3 It can be determined by TEM-EELS, which combines electron energy loss spectroscopy (EELS) with transmission electron microscopy (TEM). It should be noted that "high", "low", "large", and "small" here refer to the relative height and size between the black hard carbon layer B and the white hard carbon layer W.

[0063] Regarding the thickness ratio (T1 / T2), the ratio (T1 / T2) of the thickness T1 of the adjacent black hard carbon layer B to the thickness T2 of the white hard carbon layer W is preferably in the range of 1 / 10 to 1.5 / 1, more preferably in the range of 1 / 10 to 1 / 1. Since the thickness ratio (T1 / T2) of the repeating unit is within this range, this thickness ratio can be arbitrarily controlled to be constant or varied in the thickness direction Y of the stacked portion 1A. The thickness ratio can be gradually increased or decreased, or the thickness ratio at the beginning and end of film formation can be set to be different from that of other portions.

[0064] For example, when the thickness ratio (T1 / T2) of the black hard carbon layer B to the white hard carbon layer W is the same or approximately the same in the thickness direction Y of the laminate 1A, the low friction and chipping resistance in each repeating unit become the same. Therefore, even when the wear of the laminate 1A gradually progresses, the chipping resistance and wear resistance can be maintained in a stable and constant state. Furthermore, for example, when the thickness ratio (T1 / T2) of the black hard carbon layer B to the white hard carbon layer W gradually varies in the thickness direction Y of the laminate 1A, the low friction and chipping resistance of the repeating units in the initial sliding phase can be intentionally made to function in the low friction and chipping resistance of the repeating units in the later phases. Therefore, the chipping resistance and wear resistance can be controlled when the wear of the laminate 1A gradually progresses.

[0065] Regarding the thickness T, the thickness T of the repeating unit is preferably in the range of 0.2 to 2 μm. The thickness T of each repeating unit can be arbitrarily controlled and set within the aforementioned range. The total thickness of the stacked portion 1A formed by stacking repeating units in the thickness direction Y is in the range of 1 μm to 50 μm, preferably in the range of 3 μm to 30 μm.

[0066] The black hard carbon layer B has a network or fan-shaped tissue morphology in all or part of its structure. A portion refers to the surface side of the black hard carbon layer B, which may have a slightly network or fan-shaped tissue morphology, or it may have a three-dimensional growth morphology that can be described as network or fan-shaped. In such growth morphologies, white hard carbon is sometimes included within the black hard carbon layer B. Furthermore, the triangular wavy morphology of the black hard carbon layer B can also be viewed as a V-shape (gradually expanding from the fan axis) or a radial shape relative to the growth direction of the film.

[0067] like Figure 4 As shown, the white hard carbon layer W can be visually identified as having a fine striped pattern, and similarly, the black hard carbon layer B can also be visually identified as having a fine mesh pattern. The reason for visually identifying the repeated striped patterns of each layer (white hard carbon layer W, black hard carbon layer B) is believed to be based on the fact that, as in the case of the film-forming stack portion 1A on the sliding surface of the annular piston ring, the distance relative to the target changes continuously during film formation by rotation.

[0068] The stacked portion 1A is preferably formed with a total thickness in the range of 1 μm to 50 μm. The formation of the stacked portion 1A, formed by stacking a black hard carbon layer B and a white hard carbon layer W, with a thickness in the range described above, can be achieved, for example, by alternately performing film deposition at temperatures below 200°C and above 200°C, using the film deposition temperature (substrate temperature) of the PVD method. Film deposition at temperatures below 200°C is referred to as sp... 2 / sp 3 A slightly larger white, hard carbon layer W. On the other hand, film formation above 200°C becomes sp. 2 / sp 3 A smaller, black, hard carbon layer B. The stacked portion 1A, by alternately stacking these films, is able to form a film of the aforementioned thickness.

[0069] It should be noted that, in a portion of the laminated section 1A, there may also be interlayer bulges (not shown) spanning at least two or more layers. These bulges resemble strata uplifts, appearing as particle-like or balloon-like structures. The laminated state with these bulges is not uniformly arranged in the thickness direction Y; they are more likely to appear in the upper half, appearing as a disordered morphology, but have almost no impact on properties such as wear resistance and crack resistance. It is believed that the formation of these bulges originates from macroscopic particles formed during film formation.

[0070] The black hard carbon layer B and the white hard carbon layer W constituting the stacked portion 1A contain almost no hydrogen due to their film-forming conditions. If the hydrogen content is specifically expressed, it can be said to be 0.01 atomic% or more and less than 5 atomic%. The hydrogen content can be determined by hydrogen forward scattering (HFS) analysis, and the remaining portion is essentially composed of only carbon, preferably free of impurities other than unavoidable impurities such as N, B, and Si.

[0071] (Surface layer)

[0072] The surface layer 1C is provided on the laminated layer 1A as the outermost layer. Like the white hard carbon layer W of the laminated layer 1A, the surface layer 1C is composed of a hard carbon layer that appears white when the cross-section is observed using a bright-field TEM image.

[0073] The Vickers hardness of the surface layer 1C is lower than that of the white hard carbon layer W of the same white hard carbon layer, namely the laminate 1A, and is in the range of 800 to 1200 HV. Furthermore, this range (800 to 1200 HV) is similar to, but lower than, the range (700 to 1600 HV) of the black hard carbon layer B of the laminate 1A. It is believed that the surface layer 1C with such Vickers hardness functions to reduce friction when in contact with the object component during the initial sliding phase.

[0074] Regarding SP 2 / sp 3 For example, when comparing the black hard carbon layer B constituting the laminate 1A with the white hard carbon layer W, the results are: [black hard carbon layer B < white hard carbon layer W ≤ surface layer 1C] or [black hard carbon layer B < surface layer 1C ≤ white hard carbon layer W]. Thus, the surface layer 1C, composed of the white hard carbon layer, has a higher sp... 2 / sp 3 The hard carbon layer B is larger than the black layer B and has the same degree of hard carbon layer W as the white layer W, regarding sp. 2 / sp 3In comparison, the relative hue of the cross-section observed using bright-field TEM images is the same as that of the same white hard carbon layer W (stacked portion 1A). It should be noted that the sp... 2 / sp 3 The ratio is in the range of 0.20 to 0.80, preferably in the range of 0.30 to 0.60.

[0075] The white, hard carbon layer that makes up the surface layer 1C is composed of carbon bonds (sp.) represented by graphite. 2 The surface layer 1C has a relatively high number of bonds, resulting in low density and therefore low hardness. It should be noted that the Vickers hardness range is significantly different from that of the white hard carbon layer W constituting the laminate 1A. This surface layer 1C is formed at a film-forming temperature higher than that of each hard carbon layer (B, W) constituting the laminate 1A.

[0076] The thickness of the surface layer 1C is in the range of 0.1 to 1.0 μm, preferably in the range of 0.1 to 0.6 μm.

[0077] like Figure 4 and Figure 5 As shown, the surface layer 1C can be visually identified as a fine granular structure. The reason for this structure is not yet clear, but it is believed to be caused by the film-forming conditions of the surface layer 1C. Based on its film-forming conditions, the surface layer 1C contains almost no hydrogen. If we specifically express the hydrogen content, it can be said to be 0.01 atomic% or more and less than 5 atomic%. The hydrogen content can be determined by HFS (Hydrogen Forward Scattering) analysis. The remaining portion is essentially composed only of carbon, and preferably free of impurities other than unavoidable impurities such as N, B, and Si.

[0078] (Film formation of coating membrane)

[0079] The coating film 1 can be formed using PVD methods such as arc PVD and sputtering PVD. Preferably, a carbon target is used, and the coating film is formed by arc ion plating, where the raw material does not contain hydrogen atoms. When forming the coating film 1 by, for example, arc ion plating, the film formation conditions can include the ON / OFF of the bias voltage, the control of the bias voltage value, the adjustment of the arc current, the heating control of the substrate based on the heater, and the forced cooling of the substrate in a fixture (support) in which a cooling mechanism is incorporated.

[0080] Specifically, in the film formation of the stacked portion 1A, a black hard carbon layer B is formed by applying a high bias voltage, while a white hard carbon layer W is formed by applying a low bias voltage or no bias voltage. In the film formation of the surface layer 1C, a higher bias voltage than that applied to the black hard carbon layer B is applied. Here, "high" and "low" bias voltage refer to the absolute value; for example, -100V and -50V mean that -100V is a high bias voltage.

[0081] In the film formation of the laminate 1A, sp 2 / sp 3 A black, hard carbon layer B with a ratio of 0.05 to 0.75 is deposited using a bias voltage that causes a temperature rise. The bias voltage can be set, for example, in the range of -100 to -300V, while the arc current is in the range of 40 to 120A, and the substrate temperature is in the range of 100°C to 300°C. On the other hand, sp... 2 / sp 3 A white, hard carbon layer W with a ratio of 0.20 to 0.80 is deposited using a bias voltage that does not cause a temperature rise. The bias voltage can be 0V, or, for example, above 0V but below -50V, in which case the arc current is in the range of 40 to 120A, and film formation occurs while the substrate temperature gradually decreases without a temperature rise. It should be noted that the substrate temperature can also be adjusted by methods other than adjusting the bias voltage, such as adjusting the arc current, heater temperature, or furnace pressure.

[0082] In the film formation of the surface layer 1C, a bias voltage higher than that applied to the black hard carbon layer B is applied. If the bias voltage during the film formation of the black hard carbon layer B is, for example, -150V, then the bias voltage during the film formation of the surface layer 1C is a bias voltage higher than that (for example, -160 to -400V, preferably -170 to -250V). Within this bias voltage range, the surface layer 1C can form a film with the same morphology (fine granules) in which no substantial difference is visible. Furthermore, when forming the film with this bias voltage, the film formation temperature is set higher than the film formation temperature of each hard carbon layer (B, W) constituting the laminate 1A.

[0083] (sp 2 / sp 3 Compare)

[0084] Hard carbon layers are represented by graphite with sp bonds. 2 Carbon bonds, represented by diamond sp bonds, and other carbon bonds 3 A film in which bonds are mixed. In this application, the 1s→π transition was determined by EELS (Electron Energy Loss Spectroscopy). * Intensity and 1s→σ *Intensity, from 1s to π * Intensity is considered as sp 2 Intensity, from 1s to σ * Intensity is considered as sp 3 Intensity, the ratio is 1s→π * Intensity and 1s→σ * The ratio of strength as [sp 2 / (sp 2 +sp 3 )] than (sometimes abbreviated as "sp") 2 / sp 3 It is calculated by comparing (the ratio). Therefore, the sp mentioned in this invention is... 2 / sp 3 More precisely, it refers to the π / σ intensity ratio. Specifically, it involves applying STEM (scanning TEM) spectral imaging in this mode, with an accelerating voltage of 200 kV and a sample absorption current of 10... -9 A. Under the condition of a beam spot diameter of 1 nm, the EELS obtained at a spacing of 1 nm are accumulated and used as the average information from a region of approximately 10 nm to extract the CK absorption spectrum, and the sp is calculated. 2 / sp 3 Compare.

[0085] It should be noted that a bombardment treatment using a carbon target can be performed before the formation of the black hard carbon layer B and the white hard carbon layer W. This bombardment treatment can be performed separately before the formation of all black and white hard carbon layers B and W, or only before the formation of the black hard carbon layer B, or only before the formation of the white hard carbon layer W; it is not limited to these, and can be performed before the formation of any hard carbon layer. The bombardment treatment can improve the interlayer adhesion and suppress film deviations, and is therefore preferred in this invention. The stage at which this bombardment treatment is performed is arbitrary, but it is preferred, as in the embodiments described later, to perform the bombardment treatment before the formation of the black hard carbon layer B. Figure 8 In the example shown, the bombardment treatment is performed before the formation of the black hard carbon layer B, allowing for the visual identification of a carbon layer 13 (which may also be referred to as a "bombardment-treated layer" or "bombardment-treated carbon layer") formed only directly below the black hard carbon layer B. In the embodiments described later, as an example of the bombardment treatment conditions, film formation was performed for a given time with an arc current of approximately 40 A and a thickness of approximately 20 nm within a bias voltage range of -750 to -1000 V. However, this is not a limitation, and the value of the arc current and the thickness can be appropriately varied.

[0086] Example

[0087] The following experimental and reference examples will be used to describe the coating film and sliding component of the present invention in more detail.

[0088] [Experimental Example 1]

[0089] Piston rings are used as sliding components 10. A piston ring substrate 11 (88 mm diameter, 2.9 mm radial width, 1.2 mm axial width) is used, composed of C: 0.65 wt%, Si: 0.38 wt%, Mn: 0.35 wt%, Cr: 13.5 wt%, Mo: 0.3 wt%, P: 0.02 wt%, S: 0.02 wt%, with the remainder being iron and unavoidable impurities. A 40 μm nitrided layer is formed on this piston ring substrate 11 by nitriding, serving as an intermediate layer 12. A 0.2 μm thick metallic chromium layer is then formed by ion plating. Next, on the intermediate layer 12, a black hard carbon layer B and a white hard carbon layer W are deposited using an arc ion plating apparatus with a carbon target to form a stacked portion 1A. Then, a surface layer 1C is formed on the stacked portion 1A. It should be noted that before forming the black hard carbon layer B, a carbon layer 13 with a thickness of 20 nm was formed by bombardment treatment (bias voltage: -1000V, arc current: 40A).

[0090] A black hard carbon layer B constituting the stacked portion 1A is subjected to arc discharge for 10 minutes with a bias voltage of -150V and an arc current of 40A, forming a black hard carbon layer B with a thickness T1 of 0.18μm. A white hard carbon layer W formed on top of it is subjected to arc discharge for 20 minutes with a bias voltage of -30V (arc current of 40A), forming a white hard carbon layer W with a film thickness T2 of 0.35μm. The thickness T of the repeating unit is 0.53μm, and the film formation of this repeating unit is performed 20 times to obtain the stacked portion 1A with a total thickness of 10.6μm.

[0091] Next, a surface layer 1C is formed on the laminate 1A. The surface layer 1C is subjected to arc discharge for 30 minutes with a bias voltage of -170V and an arc current of 40A to form a surface layer 1C with a thickness of 0.50μm consisting of a white hard carbon layer. The total thickness of the laminate 1A and the surface layer 1C is 11.1μm.

[0092] [Observation of structural morphology]

[0093] For the coated film 1 obtained by film deposition, a bright-field TEM image of its cross-section was taken. The cross-sectional image of the coated film 1 was obtained by taking a bright-field TEM image of the coated film 1 with an accelerating voltage of 200 kV. The TEM image of the coated film 1 obtained in Experimental Example 1 is shown below. Figure 4 and Figure 5 .like Figure 4 and Figure 5As shown, it can be confirmed that the laminated portion 1A alternately laminates a black hard carbon layer B (represented by black) and a white hard carbon layer W (represented by white) in the thickness direction. Furthermore, fine stripe patterns are seen in the white hard carbon layer W, and the black hard carbon layer B exhibits a network or fan-shaped structure, either wholly or partially. The surface layer 1C appears to have a fine granular structure. Furthermore, due to… Figure 8 The TEM images show that directly below each of the black, hard carbon layers B, carbon layers 13 formed by bombardment can be visually identified.

[0094] The total thickness of the coating film 1, the thickness of the black hard carbon layer B, the thickness of the white hard carbon layer W, and the thickness of the surface layer 1C were determined using bright-field TEM images. In the thickness measurement, piston rings with the coating film 1 deposited near the center of the effective coating area of ​​the arc ion plating apparatus used, and piston rings with the coating film 1 deposited near the upper and lower ends, were used as measurement samples. It should be noted that the ratio (T1 / T2) of the thickness T1 of the black hard carbon layer B to the thickness T2 of the white hard carbon layer W is 0.18 / 0.35 = 0.51.

[0095] Vickers hardness and sp 2 / sp 3 Compare]

[0096] Regarding Vickers hardness, the Vickers hardness of the black hard carbon layer B is in the range of 700–1100 HV, while the Vickers hardness of the white hard carbon layer W is higher than that of the adjacent black hard carbon layer B and is in the range of 1200–1900 HV. Regarding the Vickers hardness of the surface layer 1C, it is in the range of 900–1200 HV, which is lower than the Vickers hardness of the white hard carbon layer W in the laminated layer 1A, which is also a white hard carbon layer. It should be noted that this range (900–1200 HV) is similar to, but lower than, the range (700–1600 HV) of the black hard carbon layer B in the laminated layer 1A.

[0097] It should be noted that, regarding the Vickers hardness measurement, the thickness T (=T1+T2) of the repeating unit in Experimental Example 1 is 0.53 μm, the thickness T1 of the black hard carbon layer B is 0.18 μm, the thickness T2 of the white hard carbon layer W is 0.35 μm, and the thickness of the surface layer 1C is also 0.50 μm, all of which are relatively thin. Therefore, even with the current highest level of measurement technology, it is almost impossible to measure the hardness of each individual layer. Furthermore, even if it were possible to measure from the surface, due to the thin thickness, it would be affected by the hardness of the underlying layers, making it difficult even with the current highest level of measurement technology. Therefore, the Vickers hardness here is evaluated by measuring the results obtained by forming relatively thick films of only the black hard carbon layer B, the white hard carbon layer W, and the surface layer 1C without changing the film formation conditions.

[0098] Specifically, hardness is affected by film-forming temperature. Therefore, if the substrate temperature at the end of film formation of the black hard carbon layer B, which is accompanied by a temperature rise, is set as T... B The substrate temperature at the end of film formation of the white, hard carbon layer W, which decreases with temperature, is set as T. W Then it is T B >T W In the case of a monolayer of black hard carbon layer B, after forming a 0.18 μm film of black hard carbon layer B, it was cooled until the substrate temperature dropped to T. W Upon arriving at T W The deposition of the black, hard carbon layer B begins at a specific point, with a thickness of 0.18 μm. This process is then repeated until the substrate temperature decreases to T. W The cooling and formation of a black hard carbon layer B result in a monolayer film consisting only of the black hard carbon layer B. On the other hand, in the case of a monolayer with a white hard carbon layer W, after forming a 0.35 μm white hard carbon layer W, heating is performed until the substrate temperature rises to T. B Upon arriving at T B The formation of a white, hard carbon layer W begins at a specific point, with a film thickness of 0.35 μm. This process is then repeated until the substrate temperature rises to T. B Heating and forming a white hard carbon layer W are performed to obtain a monolayer film consisting only of the white hard carbon layer W. In the surface hardness measurement, the monolayer film consisting of a black hard carbon layer B and a white hard carbon layer W with a film thickness (6 μm or more) unaffected by the substrate is adjusted to a surface roughness Ra of approximately 0.05. The Vickers hardness is measured from the surface layer using a Vickers hardness tester under a load of 100 gf. In this experimental example, the Vickers hardness measured by this method is used for evaluation. The surface layer is also measured using the same method.

[0099] sp of the laminate 1A 2 / sp3 The ratio of the black hard carbon layer B to the white hard carbon layer W is in the range of 0.20 to 0.70. Furthermore, it can be confirmed that the white hard carbon layer of the surface layer 1C, which is relatively white, is formed in a fine granular structure. Furthermore, the sp... 2 / sp 3 The ratio is in the range of 0.40 to 0.55 in each part of the surface layer 1C. It should be noted that the black hard carbon layer B, the white hard carbon layer W, and the surface layer 1C have different ratios. 2 / sp 3 The ratio is the result of measurement in each part. The value may vary at the boundary with other layers due to the influence of other layers. Therefore, the boundary with other layers is avoided as the measurement point.

[0100] [Abrasion resistance, chipping resistance, low friction, peel resistance]

[0101] The various properties of the coated film 1 after film formation were obtained by friction and wear testing using an SRV (Schwingungs Reihungund und Verschleiss) testing machine 120, which is commonly used in the evaluation of sliding parts for automobiles. Specifically, such as Figure 7 As shown, with the sliding surface of the friction and wear test sample 20 in contact with the SUJ2 material 21 serving as the sliding object, 5W-30 (with Mo-DTC) was used as lubricant, and a load of 1000N was applied while the sample was reciprocated for 10 minutes and 60 minutes. The sliding surface of the friction and wear test sample 20 was then observed using a microscope. Figure 7 In the diagram, symbol 12 represents the intermediate layer, and symbol 1 represents the coating membrane.

[0102] The obtained coating film 1 was confirmed to be free from peeling and chipping, exhibiting constant and stable chipping resistance and abrasion resistance, as well as excellent peel resistance (adhesion).

[0103] [Determination of the coefficient of friction]

[0104] The coefficient of friction was determined using a movable pad friction testing machine. The results are shown in Table 1. Regarding the coefficient of friction of the coating film 1 in Experimental Example 1, if compared with the coefficient of friction of the comparative experimental example 1 described later, which is set to 100, a friction reduction effect of up to 26% from the mixed lubrication region to the boundary lubrication region is confirmed.

[0105] [Table 1]

[0106] friction coefficient ratio Experimental Example 1 74 Experiment Example 2 67 Comparative Experiment Example 1 100 Comparative Experiment Example 2 112

[0107] As described above, the coating film 1 obtained in Experimental Example 1 exhibits good resistance to chipping and wear, as well as good resistance to aggression against the target material. Therefore, both the coating film 1 and the target material possess stable sliding characteristics. This characteristic is particularly advantageous for sliding components subjected to high loads, such as piston rings, and for the coating film itself. Compared to sliding components lacking this characteristic, it enables the formation of sliding components exhibiting constant and stable resistance to chipping and wear, as well as excellent peel resistance (adhesion). Furthermore, the coating film 1 has a surface layer 1C on its outermost surface, thus enabling a reduction in friction during the initial stage of sliding when in contact with the target component.

[0108] [Experimental Example 2]

[0109] In Experiment 2, a piston ring was also used as the sliding component 10, and the same piston ring substrate 11 as in Experiment 1 was used. The nitrided layer and intermediate layer 12 were also formed in the same manner as in Experiment 1. Regarding the repeating unit of the black hard carbon layer B and the white hard carbon layer W, in the same manner as in Experiment 1, an arc ion plating apparatus using a carbon target was used to form a film on the interlayer 12 for the stacked portion 1A and the surface portion 1C to obtain the coating film 1. Furthermore, in Experiment 2, in the same manner as in Experiment 1, the carbon layer 13 was formed by bombardment treatment before the formation of the black hard carbon layer B.

[0110] The film formation conditions in Experimental Example 2 were as follows: an arc discharge of -230V and 40A for 30 minutes resulted in a surface layer 1C with a film thickness of 0.55μm, consisting of a white hard carbon layer. The film formation conditions for the other layers in Experimental Example 1A were the same. The total thickness of the layers in Experimental Example 1A and the surface layer 1C was 11.2μm.

[0111] [Evaluation of Experiment Example 2]

[0112] The evaluation of each characteristic is the same as described above. For the coating film 1 in Experimental Example 2, its cross-sectional bright-field TEM image also shows the same characteristics as... Figure 4 and Figure 5 The same morphology. Furthermore, carbon layer 13 also indicates a similarity to... Figure 8 The same morphology applies. The Vickers hardness of the black hard carbon layer B in the laminate 1A is in the range of 700–1100 HV, while the Vickers hardness of the white hard carbon layer W is higher than that of the adjacent black hard carbon layer B and is in the range of 1200–1900 HV. Regarding the Vickers hardness of the surface layer 1C, it is in the range of 800–1100 HV lower than the Vickers hardness of the white hard carbon layer W in the laminate 1A, which is also a white hard carbon layer.

[0113] sp of the laminate 1A 2 / sp 3The ratio of the black hard carbon layer B to the white hard carbon layer W is in the range of 0.20 to 0.70. Furthermore, it can be confirmed that the white hard carbon layer of the surface layer 1C, which is relatively white, is formed in a fine granular structure. Furthermore, the sp... 2 / sp 3 The ratio is in the range of 0.45 to 0.65.

[0114] The obtained coating film 1 was confirmed to exhibit neither peeling nor cracking, and possesses constant and stable resistance to cracking and wear, as well as excellent peel resistance (adhesion). The results for the coefficient of friction are shown in Table 1. When compared with the coefficient of friction of Comparative Experiment Example 1 described later, which is set to 100, a maximum friction reduction of 33% from the mixed lubrication region to the boundary lubrication region was confirmed.

[0115] [Comparative Experiment Example 1]

[0116] In this comparative example 1, a piston ring was used as the sliding component 10, and the same piston ring substrate 11 as in example 1 was used. The nitrided layer and the intermediate layer 12 were also formed in the same manner as in example 1. Regarding the repeating unit of the black hard carbon layer B and the white hard carbon layer W, the coating film 1 was obtained by forming a film on the intermediate layer 12 using an arc ion plating apparatus with a carbon target, just as in example 1. Furthermore, in this comparative example, the carbon layer 13 was formed by bombardment treatment before the formation of the black hard carbon layer B, just as in example 1.

[0117] The film formation conditions in Comparative Example 1 were as follows: the surface layer 1C was formed by arc discharge for 10 minutes with a bias voltage of -150V (the same as the black hard carbon layer B) and an arc current of 40A, resulting in a thickness of 0.18 μm, approximately one-third the thickness of Example 1. The film formation conditions for the other layers in the stack 1A were the same as in Example 1. The combined thickness of the stack 1A and the surface layer 1C was 10.8 μm.

[0118] [Evaluation of Comparative Experiment Example 1]

[0119] The evaluation of each characteristic is the same as described in the method. For the coating film 1 of Comparative Experiment Example 1, the laminate portion 1A also shows the same characteristics as... Figure 4 and Figure 5 The same morphology. The Vickers hardness of the black hard carbon layer B in the laminate 1A is in the range of 700–1100 HV, while the Vickers hardness of the white hard carbon layer W is higher than that of the adjacent black hard carbon layer B and is in the range of 1200–1900 HV. The sp of the laminate 1A... 2 / sp 3The specific gravity is within the range of 0.05 to 0.55 in all parts of the black hard carbon layer B, and within the range of 0.20 to 0.70 in all parts of the white hard carbon layer W. It should be noted that the surface layer 1C does not exhibit the same characteristics as... Figure 4 and Figure 5 The same shape.

[0120] The obtained coating film 1 was confirmed to exhibit neither peeling nor cracking, and possesses constant and stable crack resistance, abrasion resistance, and excellent peel resistance (adhesion). The friction coefficient results showed a higher friction coefficient than those of Experimental Example 1.

[0121] [Comparative Experiment Example 2]

[0122] In this comparative example 2, a piston ring was used as the sliding component 10, and the same piston ring substrate 11 as in example 1 was used. The nitrided layer and the intermediate layer 12 were also formed in the same manner as in example 1. Regarding the repeating unit of the black hard carbon layer B and the white hard carbon layer W, in the same manner as in example 1, an arc ion plating apparatus using a carbon target was used to form a film on the intermediate layer 12, resulting in a coating film 1 without a surface layer 1C. Furthermore, in this comparative example, in the same manner as in example 1, the carbon layer 13 was formed by bombardment treatment before the formation of the black hard carbon layer B.

[0123] In this comparative experimental example 2, no film was formed on the surface layer 1C. The film formation conditions for the other layers 1A were the same as in experimental example 1. The thickness of the coating film 1 was 10.6 μm.

[0124] [Evaluation of Comparative Experiment Example 2]

[0125] The evaluation of each characteristic is the same as described in the method. Regarding the coating film 1 of Comparative Experiment Example 2, the laminate 1A exhibits the same characteristics as... Figure 4 and Figure 5 The same morphology. The results of the friction coefficients are shown in Table 1. When compared with the friction coefficient ratio of Comparative Experiment Example 1, which is set to 100, a maximum increase of 12% in friction was observed from the mixed lubrication region to the boundary lubrication region.

[0126] [Summarize]

[0127] When summarizing the results of Experiments 1 and 2 and comparing them, regarding the morphology of the laminated portion 1A, the black hard carbon layer B has a reticular or fan-shaped morphology in all or part of its structure, while the surface portion 1C has a fine granular morphology. Furthermore, in the laminated portion 1A, the Vickers hardness of the black hard carbon layer B is in the range of 700–1600 HV, and the Vickers hardness of the white hard carbon layer W is higher than that of the adjacent black hard carbon layer B, falling within the range of 1200–2200 HV. The Vickers hardness of the surface portion 1C is lower than that of the white hard carbon layer W, falling within the range of 800–1200 HV.

[0128] The present invention has been described above based on embodiments, but the present invention is not limited to the described embodiments. Various modifications can be made to the described embodiments within the same and equivalent scope as the present invention.

[0129] Symbol Explanation

[0130] 1. Coating film

[0131] 1A Lamination Section

[0132] 1C Surface Section

[0133] 10. Sliding components (piston rings)

[0134] 11. Substrate (Piston Ring Substrate)

[0135] 11a Basal layer

[0136] 12 Intermediate Layers

[0137] 13 Carbon layer formed by bombardment treatment

[0138] 16 Sliding surfaces

[0139] 20 Friction and Wear Test Samples

[0140] 21 Sliding Objects

[0141] 120 SRV testing machine

[0142] B. Black hard carbon layer

[0143] W White hard carbon layer

[0144] Y-direction thickness

Claims

1. A sliding component having a coating film on its sliding surface on a substrate, wherein, The coating film has the following characteristics: The laminated portion is formed by stacking repeating units in the thickness direction, the repeating units comprising a black hard carbon layer, which is relatively black when the cross-section is observed using a bright-field TEM image, and a white hard carbon layer, which is relatively white; and The surface layer is composed of a white, hard carbon layer disposed on the laminated portion. The black hard carbon layer has a Vickers hardness in the range of 700-1600 HV. The white hard carbon layer has a Vickers hardness that is higher than that of the adjacent black hard carbon layer and is in the range of 1200-2200 HV. The surface layer has a Vickers hardness that is lower than that of the white hard carbon layer and is in the range of 800-1200 HV. The adjacent black hard carbon layer and the white hard carbon layer [sp 2 / (sp 2 +sp 3 )] compared to the surface layer [sp 2 / (sp 2 +sp 3 The ratio is: [the black hard carbon layer < the white hard carbon layer ≤ the surface layer] or [the black hard carbon layer < the surface layer ≤ the white hard carbon layer]. The black hard carbon layer has a higher density than the adjacent white hard carbon layer.

2. The sliding component according to claim 1, wherein, The thickness of the surface layer is in the range of 0.1 to 1.0 μm, and the thickness of the repeating unit is in the range of 0.2 to 2 μm.

3. The sliding component according to claim 1 or 2, wherein, The black hard carbon layer [sp 2 / (sp 2 +sp 3 The ratio of the white hard carbon layer to the [sp] is in the range of 0.05 to 0.

75. 2 / (sp 2 +sp 3 The ratio of [sp] to the black hard carbon layer is greater than that of [sp]. 2 / (sp 2 +sp 3 The ratio of the surface layer to the [sp] value is within the range of 0.20 to 0.

80. 2 / (sp 2 +sp 3 The ratio is in the range of 0.20 to 0.

80.

4. The sliding component according to claim 1 or 2, wherein, There is a carbon layer directly below the black hard carbon layer and / or directly below the white hard carbon layer.

5. The sliding component according to claim 1 or 2, wherein, When observing the cross-section using bright-field TEM images, a hard carbon substrate film is disposed between the substrate or an intermediate layer disposed on the substrate and the coating film.

6. The sliding member according to claim 1 or 2, wherein, The sliding component is a piston ring.

7. A method for manufacturing a sliding component, comprising the method for manufacturing a sliding component according to any one of claims 1 to 6, wherein the sliding surface on a substrate has a coating film, wherein... The coating film has the following characteristics: The laminated portion is formed by stacking repeating units in the thickness direction, the repeating units comprising a black hard carbon layer, which is relatively black when the cross-section is observed using a bright-field TEM image, and a white hard carbon layer, which is relatively white; and The surface layer is composed of a white, hard carbon layer disposed on the laminated portion. In the manufacturing method, the film-forming temperature of the surface layer is higher than that of the laminated layer to form a film.

8. A coating film having: The laminated portion is formed by stacking repeating units in the thickness direction, the repeating units comprising a black hard carbon layer, which is relatively black when the cross-section is observed using a bright-field TEM image, and a white hard carbon layer, which is relatively white; and The surface layer is composed of a white, hard carbon layer disposed on the laminated portion. The black hard carbon layer has a Vickers hardness in the range of 700-1600 HV. The white hard carbon layer has a Vickers hardness that is higher than that of the adjacent black hard carbon layer and is in the range of 1200-2200 HV. The surface layer has a Vickers hardness that is lower than that of the white hard carbon layer and is in the range of 800-1200 HV. The adjacent black hard carbon layer and the white hard carbon layer [sp 2 / (sp 2 +sp 3 )] compared to the surface layer [sp 2 / (sp 2 +sp 3 The ratio is: [the black hard carbon layer < the white hard carbon layer ≤ the surface layer] or [the black hard carbon layer < the surface layer ≤ the white hard carbon layer]. The black hard carbon layer has a higher density than the adjacent white hard carbon layer.

Images