Sliding member, manufacturing apparatus of sliding member, and method for manufacturing sliding member

Abstract

To provide a sliding member, a manufacturing apparatus of the sliding member, and a method for manufacturing the sliding member in which a friction coefficient can be reduced.SOLUTION: A sliding member has diamond-like carbon film 3 having hardness distribution in a surface direction. In other words, the diamond-like carbon film 3 has an area of high hardness and an area of low hardness depending on a position in the surface direction. Herein, the diamond-like carbon film 3 has a first region 4A and a second region 4B having lower hardness than the first region 4A. In the case where a subject 10 relatively slides for the diamond-like carbon film 3, abrasion powder PD with lubrication action is generated in the second region 4B having low hardness. Further, the first region 4A and the second region 4B are alternately arranged in the surface direction. Therefore, the abrasion powder PD is accumulated in recesses 11, which are formed by shaving of the second region 4B having low hardness, by which lubrication action can be continuously exerted.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a sliding member, a manufacturing apparatus for the sliding member, and a manufacturing method for the sliding member.

Background Art

[0002] Conventionally, the oil-less conversion of sliding members used in sliding parts of machines has been promoted. As a sliding member for performing such lubrication-free sliding, a sliding member having a diamond-like carbon film is known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, as described above, in a sliding member that simply employs a diamond-like carbon film, the reduction of the friction coefficient is insufficient as a sliding member under lubrication-free conditions. Therefore, it has been required to further reduce the friction coefficient of the diamond-like carbon film.

[0005] An object of the present invention is to provide a sliding member, a manufacturing apparatus for the sliding member, and a manufacturing method for the sliding member, which can reduce the friction coefficient.

Means for Solving the Problems

[0006] The sliding member of the present invention is a sliding member that can slide relative to an object in a state of being in contact with the object, and has a diamond-like carbon film having a hardness distribution in the surface direction. The diamond-like carbon film has a first region and a second region having a lower hardness than the first region, and the first region and the second region are alternately arranged in the surface direction.

[0007] The sliding member according to the present invention has a diamond-like carbon film having a hardness distribution in the plane direction. That is, the diamond-like carbon film has a high-hardness portion and a low-hardness portion depending on the position in the plane direction. Here, the diamond-like carbon film has a first region and a second region having a lower hardness than the first region. When an object slides relative to the diamond-like carbon film, wear powder having a lubricating action is generated in the second region having a low hardness. Further, the first region and the second region are alternately arranged in the plane direction. Therefore, the wear powder accumulates in the recess formed by scraping the second region having a low hardness, so that the lubricating action can be continuously exerted. From the above, the friction coefficient of the sliding member can be reduced.

[0008] The sliding member further includes a base material that supports the diamond-like carbon film. The base material has an uneven shape. The first region may be formed at a position corresponding to the recess of the base material, and the second region may be formed at a position corresponding to the convex portion of the base material. In this way, by simply providing the base material with an uneven shape, the first region and the second region can be easily formed on the diamond-like carbon film.

[0009] The manufacturing apparatus for a sliding member according to the present invention is a manufacturing apparatus for a sliding member that can slide relative to an object in a state of being in contact with the object, and includes a film forming portion that forms a diamond-like carbon film by attaching a film forming material to a base material. The film forming portion includes an adjustment portion capable of making the hardness distribution of the diamond-like carbon film non-uniform in the plane direction.

[0010] In the manufacturing apparatus for a sliding member according to the present invention, the film forming portion includes an adjustment portion capable of making the hardness distribution of the diamond-like carbon film non-uniform in the plane direction. Therefore, the diamond-like carbon film has a high-hardness portion and a low-hardness portion depending on the position in the plane direction. When an object slides relative to the diamond-like carbon film, wear powder having a lubricating action is generated at the portion having a low hardness. Therefore, the friction coefficient of the sliding member manufactured by the manufacturing apparatus can be reduced.

[0011] The adjustment part may be an electrode on which the base material is placed or the base material itself. In this case, without providing an additional mechanism for the electrode or the base material, by devising the structure of the electrode or the base material, a sliding member with a low coefficient of friction can be easily manufactured.

[0012] The adjustment part may have a concavo-convex shape continuous in the plane direction. In this case, the concavo-convex shape can adjust the ease of arrival of hydrogen ions at each location of the diamond-like carbon film. Thereby, a sliding member with a low coefficient of friction can be easily manufactured only by providing a concavo-convex shape in the adjustment part.

[0013] The adjustment part may alternately have regions with different materials in the plane direction. The regions with different materials can adjust the ease of arrival of hydrogen ions at each location of the diamond-like carbon film. Thereby, a sliding member with a low coefficient of friction can be easily manufactured only by providing regions with different materials in the adjustment part.

[0014] The adjustment part may be an electrode to which a bias voltage is applied. Thereby, by devising the structure of the electrode to which the bias voltage is applied, a sliding member with a low coefficient of friction can be easily manufactured.

[0015] The method for manufacturing a sliding member according to the present invention is a method for manufacturing a sliding member that can slide relative to an object in a state of being in contact with the object, and includes a film-forming step of forming a diamond-like carbon layer by attaching a film-forming material to a base material. In the film-forming step, the hardness distribution of the diamond-like carbon layer is made non-uniform in the plane direction.

[0016] According to the method for manufacturing a sliding member, the same functions and effects as those of the above-described manufacturing apparatus for a sliding member can be obtained.

Effects of the Invention

[0017] According to the present invention, it is possible to provide a sliding member capable of reducing the coefficient of friction, a manufacturing apparatus for a sliding member, and a method for manufacturing a sliding member.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals and redundant descriptions are omitted. Also, the positional relationships such as up, down, left, and right are based on the positional relationships in the drawings.

[0020] FIG. 1 is a side view showing a sliding member 1 according to the present embodiment. The sliding member 1 is a member that can slide relatively in a state of being in contact with an object. Since the sliding member 1 can be applied to any location where sliding occurs, its use is not particularly limited. However, examples of the use of the sliding member 1 include, for example, a mold clamping drive unit, a toggle, an adjusting nut tie bar, a toggle support, etc. in a molding apparatus. In addition, examples of the use of the sliding member 1 include, for example, a piston ring, a bush, a sliding bearing, etc. As shown in FIG. 1, the sliding member 1 includes a base material 2 and a diamond-like carbon film 3.

[0021] The base material 2 is a member that supports the diamond-like carbon film 3. The base material 2 is a flat member and has a main surface 2a on which the diamond-like carbon film 3 is formed. The base material 2 is not particularly limited as long as it has the strength required as the sliding member 1. Examples of the material of the base material 2 include conductive materials such as iron, cast iron, cemented carbide, stainless steel, and aluminum alloy. When the material of the base material 2 is an iron-based material, hardening treatments such as quenching and tempering or nitriding treatment may be performed. When the sliding member 1 is used as a piston ring, it is preferable to use martensitic stainless steel, spring steel, carbon steel, etc. that have been conventionally applied as the base material. The thickness of the base material 2 is not particularly limited. Also, the shape of the base material 2 is not particularly limited, and it may be a cylindrical or spherical member. Even if it is a curved surface, it is possible to apply a bias voltage.

[0022] The diamond-like carbon film 3 (Diamond-Like Carbon, DLC) is a thin film of carbon that has properties similar to diamond. The diamond-like carbon film 3 has main surfaces 3a and 3b. The main surface 3b is provided on the main surface 2a of the base material 2. The main surface 3b is a surface that functions as the sliding surface of the sliding member 1. The diamond-like carbon film 3 is a film that has both carbon-carbon bonds of diamond and graphite. The diamond-like carbon film 3 has properties such as a low friction coefficient, chemical stability, corrosion resistance, wear resistance, and insulation. In the diamond-like carbon film 3, carbon with sp3 bonds and sp2 bonds is mixed. The carbon with sp3 bonds forms the crystal structure of diamond, and the carbon with sp2 bonds forms the crystal structure of graphite. The properties of the diamond-like carbon film 3 can be adjusted by the ratio of these bonds. Although the thickness of the diamond-like carbon film 3 is not particularly limited, it may be set to about 0.1 μm to 5 μm, for example. The diamond-like carbon film 3 has carbon (C) and hydrogen (H) as main components, and if necessary, each element such as silicon (Si), oxygen (O), nitrogen (N), etc. can be contained alone or in combination to impart a functional group to the amorphous carbon film.

[0023] FIG. 2(a) is an enlarged cross-sectional view of the diamond-like carbon film 3. As shown in FIG. 2(a), the diamond-like carbon film 3 has a hardness distribution in the plane direction. The plane direction is the direction in which the main surfaces 3a and 3b of the diamond-like carbon film 3 extend. The diamond-like carbon film 3 has a first region 4A and a second region 4B. The first region 4A is a region with high hardness. The second region 4B is a region with low hardness. The second region 4B is a region with lower hardness than the first region 4A. Further, the first region 4A and the second region 4B are alternately arranged in the plane direction. The first region 4A and the second region 4B extend from the main surface 3a to the main surface 3b.

[0024] As shown in FIG. 2(b), when the diamond-like carbon film 3 slides relative to the object 10, the soft second region 4B preferentially wears. As a result, wear powder PD having a lubricating action is generated on the main surface 3b side. As a result, the friction coefficient of the diamond-like carbon film 3 is reduced. Further, as the second region 4B wears, a concave portion 11 is formed on the main surface 3b side. The wear powder PD accumulates in the concave portion 11. As a result, the wear powder PD is continuously supplied to the main surface 3b which is the sliding surface, and a continuous lubricating action is exhibited. For example, when a diamond-like carbon film having a constant hardness in the plane direction is employed, the friction coefficient can be reduced only to a level slightly below 0.1 under non-lubricated conditions. In contrast, the friction coefficient of the diamond-like carbon film 3 of the sliding member 1 according to the present embodiment can be reduced to a value below 0.03.

[0025] The sizes of the first region 4A and the second region 4B in the plane direction for obtaining the lubricating effect as described above are not particularly limited. For example, the dimension TA of the first region 4A in the plane direction may be set to about 1 μm to 100 μm. The dimension TB of the second region 4B in the plane direction may be set to about 1 μm to 100 μm. The hardness of each of the regions 4A and 4B is not particularly limited, but the hardness (Vickers hardness) of the first region 4 may be set to about 600 HV to 3000 HV, for example. The first region 4A is harder than the mating material, and the second region 4B is softer than the mating material.

[0026] Next, the manufacturing apparatus and manufacturing method of the sliding member 1 according to the present embodiment will be described. As a method for manufacturing the diamond-like carbon film 3, a PVD method (Physical Vapor Deposition) or a CVD method (Chemical Vapor Deposition) may be employed. In the PVD method, a solid (graphite) may be used as a carbon raw material, and in the CVD method, a gas (hydrocarbon such as methane) may be used. As the PVD method, an arc, sputtering, laser evaporation method, or the like may be employed. As the CVD method, a plasma CVD (PE-CVD method) or the like that forms a film by a reaction gas may be employed. Examples of the plasma CVD method include a high-frequency plasma CVD method that uses high-frequency discharge, a DC plasma CVD method that uses DC discharge, and a microwave plasma CVD method that uses microwave discharge. However, any method may be employed as long as it is a plasma apparatus that uses a gas as a raw material.

[0027] FIG. 3 is a diagram showing an example of a manufacturing apparatus 100 for a sliding member 1. FIG. 3 shows a manufacturing apparatus 100 using a DC plasma CVD method. The manufacturing apparatus 100 includes a chamber 101, a film forming section 102, and a power source 106. The chamber 101 is a container that keeps the internal space in a vacuum. The film forming section 102 forms a diamond-like carbon film 3 by attaching a film forming material M to a substrate 2. The film forming section 102 is disposed in the chamber 101. The film forming section 102 has electrodes 103 and 104 that face each other while being separated from each other. The electrode 103 functions as a mounting section for mounting the substrate 2. The electrode 103 is also an electrode to which a bias voltage is applied. The power source 106 is connected to the electrodes 103 and 104. The film forming section 102 of the manufacturing apparatus 100 includes an adjustment section 110 capable of making the hardness distribution of the diamond-like carbon film 3 non-uniform in the plane direction.

[0028] In the manufacturing apparatus 100, the substrate 2 is placed on the electrode 103 in the chamber 101. Next, the inside of the chamber 101 is evacuated. Next, a source gas such as a hydrocarbon gas is introduced into the chamber 101. Thereafter, a voltage is applied to the electrodes 103 and 104 to generate plasma. The film forming material M (such as carbon ions) in the plasma is accelerated toward the substrate 2 under the influence of the electric field and collides with and deposits on the substrate 2. By repeating this deposition process, the diamond-like carbon film 3 is formed (film forming process). In this film forming process, the adjustment section 110 makes the hardness distribution of the diamond-like carbon layer 3 non-uniform in the plane direction.

[0029] First, the case where the adjustment section 110 is the electrode 103 for mounting the substrate 2 will be described. FIG. 4 is a diagram showing the configuration of the electrode 103 that functions as the adjustment section 110. The electrode 103 that functions as the adjustment section 110 has a structure such that the surface charge of the mounting surface 103a for mounting the substrate 2 is non-uniform in the plane direction. Here, H + (m / z = 1) is more strongly affected by the electric field than C + (m / z = 12). Therefore, among the substrates 2 placed on the electrode 103, at the locations with a large amount of charge, H +is likely to impinge. The diamond-like carbon film 3 has a lower hardness in a portion with a higher hydrogen content, and a second region 4B is formed in that portion. On the other hand, among the substrates 2 placed on the electrode 103, H + is less likely to impinge. The diamond-like carbon film 3 has a higher hardness in a portion with a lower hydrogen content, and a first region 4A is formed in that portion. Note that various ion species such as CH4 + and H2 + may be formed.

[0030] Specifically, the electrode 103 that functions as the adjustment unit 110 may have a concavo-convex shape continuous in the plane direction. The electrode 103 has a convex portion 111A having a mounting surface 103a and a concave portion 111B having a bottom surface at a position lower than the mounting surface 103a. The electrode 103 alternately has the convex portion 111A and the concave portion 111B in the plane direction. In the substrate 2 placed on the electrode 103 having such a configuration, the charge increases at the portion where the convex portion 111A contacts the mounting surface 103a. Therefore, the amount of H + impinging at that portion increases, and a second region 4B with a lower hardness of the diamond-like carbon film 3 is formed. In the substrate 2, the charge decreases at the portion where the concave portion 111B does not contact the electrode 103. Therefore, the amount of H + impinging at that portion decreases, and a first region 4A with a higher hardness of the diamond-like carbon film 3 is formed.

[0031] The electrode 103 that functions as the adjustment unit 110 may alternately have regions with different materials in the plane direction. The electrode 103 has a first material region 112A made of a material that easily collects charges and a second material region 112B made of a material that hardly collects charges. The electrode 103 alternately has the first material region 112A and the second material region 112B in the plane direction. In the substrate 2 placed on the electrode 103 having such a configuration, the charge increases at the portion where it contacts the first material region 112A that easily collects charges. Therefore, the amount of H +As the amount increases, a second region 4B with a low hardness of the diamond-like carbon film 3 is formed. In the base material 2, the amount of charge decreases at a location in contact with the second material region 112B where it is difficult to collect charge. Therefore, at this location, the incident H + As the amount decreases, a first region 4A with a high hardness of the diamond-like carbon film 3 is formed. Electrical conductivity may be adopted as a physical property parameter indicating the ease of charge collection. The first material region 112A has lower electrical conductivity than the second material region 112B. The materials employed in the first material region 112A and the second material region 112B are not particularly limited. For example, as the material of the first material region 112A, a resin material, ceramics, etc. may be adopted. On the other hand, as the material of the second material region 112B, a metal material with high electrical conductivity, etc. may be adopted.

[0032] Next, the case where the adjustment unit 110 is the base material 2 will be described. FIG. 5 is a diagram showing the configuration of the base material 2 that functions as the adjustment unit 110. The base material 2 that functions as the adjustment unit 110 has an uneven shape on the main surface 2a side where the diamond-like carbon film 3 is formed. The base material 2 has a convex portion 113A protruding upward and a concave portion 113B recessed downward. The base material 2 has the convex portion 113A and the concave portion 113B alternately in the plane direction. In the example shown in FIG. 5, the convex portion 113A protrudes in a triangular shape. The concave portion 113B is recessed in a triangular shape. However, the shapes of the convex portion 113A and the concave portion 113B are not particularly limited. In the vicinity of the main surface 2a of the base material 2, C+ is pulled by the convex portion 113A protruding upward, and the direction of the momentum changes slightly. Also, in the convex portion 113A protruding upward, the ratio of incident H + is higher. The diamond-like carbon film 3 has a lower hardness at positions corresponding to the convex portions 113A with a higher hydrogen content, and the second region 4B is formed at such positions. The diamond-like carbon film 3 has a higher hardness at positions corresponding to the concave portions 113B with a lower hydrogen content, and the first region 4A is formed at such positions.

[0033] As described above, by providing an uneven shape on the main surface 2a of the base material 2 to make it rough, it functions as the adjustment unit 110. Here, as an index of the roughness of the base material 2, the arithmetic mean roughness Ra corresponding to the height of the convex portion 113A or the concave portion 113B may be adopted. The arithmetic mean roughness Ra of the base material 2 functioning as the adjustment unit 110 may be greater than 0.2 μm. Further, as an index of the roughness of the base material 2, the average wavelength Rλa of the roughness curve may be adopted. The wavelength Rλa of the base material 2 functioning as the adjustment unit 110 may be greater than 6 μm.

[0034] Note that the base material 2 may have regions with different materials alternately in the plane direction, like the electrode 103 shown in Fig. 4(b). In this case, since the amount of H + flying onto the main surface 2a of the base material 2 changes according to the material region, the first region 4A with high hardness and the second region 4B with low hardness are alternately formed.

[0035] Next, the operation and effects of the sliding member 1, the manufacturing apparatus 100 for the sliding member 1, and the manufacturing method for the sliding member 1 according to the embodiment of the present invention will be described.

[0036] The sliding member 1 according to the present embodiment has a diamond-like carbon film 3 having a hardness distribution in the plane direction. That is, the diamond-like carbon film 3 has portions with high hardness and portions with low hardness depending on the position in the plane direction. Here, the diamond-like carbon film 3 has a first region 4A and a second region 4B having a lower hardness than the first region 4A. When the object 10 slides relative to the diamond-like carbon film 3, wear powder PD having a lubricating action is generated in the second region 4B having a lower hardness. Further, the first region 4A and the second region 4B are alternately arranged in the plane direction. Therefore, the wear powder PD accumulates in the recess 11 formed by the second region 4B having a lower hardness being worn away, so that the lubricating action can be continuously exerted. From the above, the friction coefficient of the sliding member 1 can be reduced.

[0037] The sliding member 1 further includes a base material 2 that supports the diamond-like carbon film 3. The base material 2 has an uneven shape. The first region 4A may be formed at a position corresponding to the concave portion 113B of the base material 2, and the second region 4B may be formed at a position corresponding to the convex portion 113A of the base material 2 (see FIG. 5). In this way, by simply providing the base material 2 with an uneven shape, the first region 4A and the second region 4B can be easily formed on the diamond-like carbon film 3.

[0038] The manufacturing apparatus 100 for the sliding member 1 according to the present embodiment is a manufacturing apparatus for the sliding member 1 that can relatively slide in contact with the object 10. The manufacturing apparatus 100 includes a film forming unit 102 that forms the diamond-like carbon film 3 by attaching a film forming material to the base material 2. The film forming unit 102 includes an adjustment unit 110 that can make the hardness distribution of the diamond-like carbon film 3 non-uniform in the plane direction.

[0039] In the manufacturing apparatus 100 for the sliding member 1 according to the present embodiment, the film forming unit 102 includes an adjustment unit 110 that can make the hardness distribution of the diamond-like carbon film 3 non-uniform in the plane direction. Therefore, the diamond-like carbon film 3 has high-hardness portions and low-hardness portions depending on the position in the plane direction. When the object 10 relatively slides with respect to the diamond-like carbon film 3, wear powder having a lubricating action is generated at the low-hardness portions. Therefore, the friction coefficient of the sliding member 1 manufactured by the manufacturing apparatus 100 can be reduced.

[0040] The adjustment unit 110 may be the electrode 103 on which the base material 2 is placed, or the base material 2. In this case, without providing an additional mechanism for the electrode 103 or the base material 2, by devising the structure of the electrode 103 or the base material 2, the sliding member 1 with a low friction coefficient can be easily manufactured.

[0041] The adjustment part 110 may have an uneven shape that is continuous in the plane direction. In this case, the uneven shape can adjust the ease of incidence of hydrogen ions to each part of the diamond-like carbon film 3. Thereby, by simply providing the adjustment part 110 with the uneven shape, the sliding member 1 with a low coefficient of friction can be easily manufactured.

[0042] The adjustment part 110 may alternately have regions 112A and 112B that are different in material from each other in the plane direction. The regions 112A and 112B that are different in material from each other can adjust the ease of incidence of hydrogen ions to each part of the diamond-like carbon film 3. Thereby, by simply providing the adjustment part 110 with the regions 112A and 112B that are different in material, the sliding member 1 with a low coefficient of friction can be easily manufactured.

[0043] The adjustment part 110 may be an electrode 103 to which a bias voltage is applied. Thereby, by devising the structure of the electrode 103 to which the bias voltage is applied, the sliding member 1 with a low coefficient of friction can be easily manufactured.

[0044] The manufacturing method of the sliding member 1 according to the present embodiment is a manufacturing method of the sliding member 1 that can slide relatively in a state of being in contact with the object 10, and includes a film forming step of forming the diamond-like carbon layer 3 by attaching a film forming material to the base material 2. In the film forming step, the hardness distribution of the diamond-like carbon layer 3 is made non-uniform in the plane direction.

[0045] According to the manufacturing method of the sliding member 1, the same operations and effects as those of the above-described manufacturing apparatus 100 of the sliding member 1 can be obtained.

[0046] The present invention is not limited to the above-described embodiments.

[0047] The configuration of the manufacturing apparatus of the sliding member is not limited to that shown in FIG. 3, and a configuration of a manufacturing apparatus corresponding to the manufacturing method of the diamond-like carbon film 3 may be adopted.

Explanation of Reference Numerals

[0048] 1... Sliding member, 2... Base material, 3... Diamond-like carbon film, 4A... First region, 4B... Second region, 100... Manufacturing apparatus, 103... Electrode, 110... Adjustment unit, 113A... Protrusion, 113B... Recess.

Claims

1. A sliding member that can slide relatively in contact with an object, having a diamond-like carbon film having a hardness distribution in the plane direction, wherein the diamond-like carbon film has a first region and a second region having a lower hardness than the first region, and the first region and the second region are alternately arranged in the plane direction. A sliding member.

2. further comprising a substrate that supports the diamond-like carbon film, wherein the substrate has an uneven shape, the first region is formed at a position corresponding to a concave portion of the substrate, the second region is formed at a position corresponding to a convex portion of the substrate. The sliding member according to claim 1.

3. A manufacturing apparatus for a sliding member that manufactures a sliding member that can slide relatively in contact with an object, comprising a film-forming portion that forms a diamond-like carbon film by attaching a film-forming material to a substrate, wherein the film-forming portion includes an adjustment portion capable of making the hardness distribution of the diamond-like carbon film non-uniform in the plane direction. A manufacturing apparatus for a sliding member.

4. The adjustment portion is an electrode on which the substrate is placed or the substrate. The manufacturing apparatus for a sliding member according to claim 3.

5. The adjustment portion has a continuous uneven shape in the plane direction. The manufacturing apparatus for a sliding member according to claim 3.

6. The adjustment portion has regions of different materials alternately in the plane direction. The manufacturing apparatus for a sliding member according to claim 3.

7. The adjustment portion is an electrode to which a bias voltage is applied. The manufacturing apparatus for a sliding member according to claim 3.

8. A manufacturing method for a sliding member that manufactures a sliding member that can slide relatively in contact with an object, comprising a film-forming step of forming a diamond-like carbon layer by attaching a film-forming material to a substrate, wherein in the film-forming step, the hardness distribution of the diamond-like carbon layer is made non-uniform in the plane direction. A manufacturing method for a sliding member.

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