JP2022100954A - Hard carbon film and method for depositing the same - Google Patents

Abstract

To provide a hard carbon film capable of suppressing peeling from a base material even to a member rolled and slid in the presence of lubricant to maintain excellent slidability over a long term, and a method for depositing the same.SOLUTION: A hard carbon film covering at least a part of a region having a lubricant contacted on a base material has a plurality of holes having one or more corners and formed on a surface. A method for depositing the hard carbon film comprises: a hard carbon film formation step of forming the hard carbon film on the base material; and a hole formation step of forming the plurality of holes in the formed hard carbon film. The hard carbon film formation step is a composite process step of performing film deposition by a plasma CVD method using hydrocarbon as a raw material and film deposition by a sputtering method using solid carbon as a sputtering cathode in parallel in the same vacuum chamber; and the hole formation step is a step of forming the holes by polishing and removing carbon flakes generated from the sputtering cathode and fixed on the surface of the hard carbon film.SELECTED DRAWING: Figure 1

Description

The present invention relates to a hard carbon film and a method for forming a film thereof.

The hard carbon (DLC: diamond-like carbon) film has excellent sliding properties such as low friction, high wear resistance, and low cohesiveness (seizure resistance). Therefore, for example, machines / devices and gold It is widely used as a sliding member for molds, cutting tools and automobile parts.

However, when such a hard carbon film is used in the presence of a lubricant, the slidability of the hard carbon film deteriorates when the sliding portion becomes poorly lubricated, and the hard carbon film peels off from the base material, and finally. There is a risk of damage to the members due to fatigue failure.

Further, with the recent decrease in viscosity of the lubricant, such a poor lubrication state has come to occur in a short time.

For these reasons, various techniques have been developed for hard carbon films that can suppress peeling of the hard carbon film from the substrate and maintain slidability for a long period of time by delaying the occurrence of poor lubrication. Proposed.

For example, Patent Document 1 proposes that a lubricant reservoir is formed on a hard carbon film, and the angle between the side wall surface of the lubricant reservoir and the outer surface of the rigid carbon film is made larger than 90 degrees. Then, Patent Document 2 proposes to form granular irregularities densely. Further, Patent Document 3 proposes to form a recess on the sliding surface to form a film made of a lipophilic substance so as to cover the inner surface of the recess, and Patent Document 4 proposes to form a hard carbon film. It has been proposed to form recesses by using plasma etching or the like.

These techniques are basically techniques that delay the depletion of the lubricant and suppress the occurrence of poor lubrication by forming a dent that does not come into direct contact with the sliding part and storing the lubricant in this dent. be.

Japanese Unexamined Patent Publication No. 2005-172082 Japanese Unexamined Patent Publication No. 2013-087197 Japanese Unexamined Patent Publication No. 2012-197900 Japanese Patent No. 4442349

However, although each of the above-mentioned techniques exerts some effect on general sliding, it is still not sufficient, and particularly on rolling and sliding members such as engine members for a long period of time. The maintenance of slidability is insufficient, and the demand for improvement is increasing.

Therefore, the present invention provides a hard carbon film capable of suppressing peeling from the substrate and maintaining excellent slidability for a long period of time even for a member that rolls and slides in the presence of a lubricant. It is an object to provide the film forming method.

As a result of diligent studies to solve the above problems, the present inventor has found that the above problems can be solved by the invention described below, and has completed the present invention.

The invention according to claim 1 is
A hard carbon film that covers at least part of the contact area of the lubricant on the substrate.
A hard carbon film characterized in that a plurality of holes having one or more corners are formed on the surface.

The invention according to claim 2 is
The hard carbon film according to claim 1, wherein the length of the longest portion of the hole is 10 to 200 μm.

The invention according to claim 3 is
The hard carbon film according to claim 1 or 2, wherein the ratio of the pores to the film surface is 7 to 23%.

The invention according to claim 4 is
The hard carbon film according to any one of claims 1 to 3, wherein the arithmetic average roughness Ra of the surface is 0.01 to 0.07 μm.

The invention according to claim 5 is
The hard carbon film according to any one of claims 1 to 4, wherein the maximum valley depth Rv of the pores is 0.04 to 0.23 μm.

The invention according to claim 6 is
The hard carbon film according to any one of claims 1 to 5, wherein the oil reservoir depth Rvk of the pores is 0.03 to 0.35 μm.

The invention according to claim 7 is
It is formed on the intermediate layer formed on the base material, and is formed on the intermediate layer.
The hard carbon film according to any one of claims 1 to 6, wherein the intermediate layer is a metal-containing hard carbon layer containing chromium or tungsten.

The invention according to claim 8 is
One of claims 1 to 7, wherein the base material is composed of a base material main body portion and a chromium or tungsten metal base layer formed on the base material main body portion. The rigid carbon film described in the section.

The invention according to claim 9 is
The method for forming a hard carbon film according to any one of claims 1 to 6.
A hard carbon film forming step of forming a hard carbon film on the base material,
It is provided with a pore forming step of forming a plurality of the pores with respect to the formed hard carbon film.
The hard carbon film forming step is a composite process step in which a film formation by a plasma CVD method using a hydrocarbon as a raw material and a film formation by a sputtering method using solid carbon as a sputtering cathode are performed in parallel in the same vacuum chamber. And
The hard carbon film is characterized in that the pore forming step is a step of forming the pores by polishing and removing carbon flakes generated from the sputtered cathode and fixed on the surface of the hard carbon film. This is a film forming method.

The invention according to claim 10 is
The method for forming a hard carbon film according to claim 7.
An intermediate layer forming step of forming a metal-containing hard carbon layer containing chromium or tungsten as an intermediate layer on the substrate,
A hard carbon film forming step of forming a hard carbon film on the intermediate layer,
It is provided with a pore forming step of forming a plurality of the pores with respect to the formed hard carbon film.
The intermediate layer forming step is a composite process step in which a film formation by a plasma CVD method using a hydrocarbon as a raw material and a film formation by a sputtering method using chromium or tungsten as a sputtering cathode are performed in parallel in the same vacuum chamber. And
The hard carbon film forming step is a composite process step in which a film formation by a plasma CVD method using a hydrocarbon as a raw material and a film formation by a sputtering method using solid carbon as a sputtering cathode are performed in parallel in the same vacuum chamber. And
The hard carbon is characterized in that the pore forming step is a step of forming the pores by removing carbon fragments generated by the collapse of the carbon film adhering to the surface of the sputtered cathode in the intermediate layer forming step. This is a film forming method.

The invention according to claim 11 is
The hard carbon according to claim 9 or 10, wherein a base material forming step of forming a metal base layer of chromium or tungsten to form the base material is provided on the base material main body portion. This is a film forming method.

The invention according to claim 12 is
Claims 9 to 11 are characterized in that the surface of the substrate is cleaned in advance by exposing it to plasma of at least one gas selected from the group consisting of hydrogen gas, oxygen gas and noble gas. The method for forming a hard carbon film according to any one of the above items.

According to the present invention, a hard carbon film capable of suppressing peeling from a base material and maintaining excellent slidability for a long period of time even for a member that rolls and slides in the presence of a lubricant. The film forming method can be provided.

It is a surface SEM image of the hard carbon film which concerns on one Embodiment of this invention. It is sectional drawing which shows typically the form of the hard carbon film which concerns on one Embodiment of this invention. It is a schematic diagram which shows an example of a film forming apparatus. It is a schematic diagram which shows the state of generation of carbon flakes in a film forming process. It is a conceptual diagram explaining the generation mechanism of carbon flakes. It is a surface SEM image of a hard carbon film formed by arc vapor deposition. It is a surface SEM image of a hard carbon film formed by Plasmas CVD. It is a figure explaining the formation of the two-layer structure of the surface layer (DLC film) and the intermediate layer in one embodiment of the present invention. It is a figure which shows the relationship between the flake abundance and the film thickness of a DLC film. It is a microscope image of a DLC film, and FIGS. (A) to (d) are images of a DLC film having film thicknesses of 0.8 μm, 1.4 μm, 2.0 μm, and 3.8 μm, respectively. It is a figure which shows the relationship between the arithmetic mean roughness Ra of a DLC film, and the film thickness. It is a figure which shows the relationship between the maximum valley depth Rv and the film thickness of a DLC film. It is a figure which shows the relationship between the oil accumulation depth Rvk of a DLC film, and the film thickness. It is a schematic diagram which shows an example of a thrust tester. It is a microscope image which shows the test result of the thrust test.

[1] Hard carbon film according to the present invention 1. Outline of Hard Carbon Film First, an outline of the hard carbon film (hereinafter, also referred to as “DLC film”) according to the present invention will be described. The hard carbon film according to the present invention is a hard carbon film that covers at least a part of a portion of a substrate that comes into contact with a lubricant, and holes having one or more corners are formed on the surface of the hard carbon film. It is characterized by being formed in multiples.

In the presence of the lubricant, the plurality of holes provided on the surface of the hard carbon film can each hold the lubricant and act as an oil pocket to supply the lubricant to the sliding surface. Even when the members that roll and slide in the presence of the lubricant repeatedly come into contact with each other, it is possible to prevent the lubricant from being exhausted on the sliding surface. As a result, peeling from the base material can be suppressed for a long period of time, and deterioration of slidability and rolling wear resistance can be suppressed, so that excellent slidability can be maintained for a long period of time.

Further, in the present invention, unlike the circular droplets generated at the time of film formation by an arc vapor deposition method or the like, each hole is provided with one or more corners. Having one or more corners in the hole makes it easier to hold the lubricant used in the part compared to a simple circular recess, so hard carbon with only a traditional circular recess. Compared to the membrane, it can maintain excellent slidability for a much longer period of time. Examples of the lubricant include engine oil, low-viscosity oil, frozen base oil, grease and the like.

[2] Specific Embodiments Hereinafter, the present invention will be specifically described with reference to the drawings based on the embodiments.

1. 1. Hard carbon film (1) Surface condition First, the surface condition of the hard carbon film will be described. FIG. 1 is an SEM image of the surface of the DLC film according to the present embodiment, and is an image of the surface of the DLC film of the sample A in the examples described later. As shown in FIG. 1, a large number of fine pores are formed on the surface of the DLC film, and the pores are distributed almost uniformly on the surface of the DLC film. Also, the individual pores are irregular rather than circular when the membrane is viewed from the surface and have one or more corners.

Holes with corners have a better lubricant retention function than conventionally formed holes without corners, and because of their large size, they perform better as oil pockets and have a larger amount of lubricant. Can be stored.

(2) Structure The type and film thickness of the DLC film are not particularly limited, and a known DLC film can be used with a known film thickness.

Specific examples thereof include a hydrogen-containing DLC (a-C: H) having a hydrogen content of 5 to 25 at% and a film thickness of several nm to several μm.

Further, for example, in order to improve the adhesion to the base material (base material) and reduce the friction coefficient, for example, with a lower layer made of low hydrogen or hydrogen-free DLC (a-C) having a hydrogen content ratio of less than 5 at%. , The two-layer structure composed of the upper layer made of the hydrogen-containing DLC (a-C: H) may be used.

2. 2. DLC film forming method Next, a DLC film forming method will be described. 2A and 2B are cross-sectional views schematically showing the morphology of the DLC film according to the present embodiment, where FIG. 2A shows a state before pore formation and FIG. 2B shows a state after pore formation. In FIG. 2, 1 is a DLC film, 2 is a base material, F is a carbon flake (hereinafter, also simply referred to as “flake”), and H is a pore. In FIG. 2, the base 3 is formed between the DLC film 1 and the base material 2.

As shown in FIG. 2A, flakes F are fixed in the DLC film 1 before forming the pores in a state of being partially embedded in the DLC film 1, and the portion protruding from the surface is extremely thin. It is covered with the DLC film 1. Since the flake F has a weak fixing force with the DLC film 1, the flake F can be easily separated from the DLC film 1 only by applying a small external force to the protruding portion. Then, as shown in FIG. 2B, holes H having the same shape and size as the flakes F are formed in the marks where the flakes F are detached.

In the DLC film before pore formation shown in FIG. 2A, plasma CVD using a hydrocarbon as a raw material and deposition by sputtering using solid carbon as a sputtering cathode are performed in parallel in the same vacuum chamber. Formed by a complex process.

FIG. 3 is a schematic view showing an example of a film forming apparatus. FIG. 4 is a schematic diagram showing how carbon flakes are generated in the DLC film forming process. Further, FIG. 5 is a conceptual diagram illustrating the mechanism of carbon flake generation. In FIGS. 3 to 5, 4 is a film forming apparatus, 41 is a vacuum chamber, and 42 is a sputtering cathode. Further, 2 is a base material as described above.

As shown in FIG. 3, the film forming apparatus 4 includes a cylindrical vacuum chamber 41 rotatably supported at the center of a circle on the bottom surface of a circle, a spatter cathode 42 fixed to a side wall surface of the vacuum chamber 41, and a spatter cathode 42. It has a circular substrate support and a bias power supply. The vacuum chamber 41 includes an air supply port and an exhaust port.

At the time of film formation, first, the gas in the vacuum chamber 41 is exhausted, and then a mixed gas of Ar and a hydrocarbon such as methane or ethane is supplied to keep the inside of the vacuum chamber 41 at a predetermined gas pressure. Next, a DC of a predetermined voltage or a pulsed bias voltage is applied to the sputtering cathode 42 to generate Ar plasma inside the sputtering cathode 42. The generated Ar plasma turns hydrocarbons into plasma to generate hydrocarbon ions, and a DLC film is deposited as a layer on the surfaces of the base material 2 and the sputtering cathode 42.

At this time, as shown in FIGS. 4 and 5, the surface of the sputtered cathode 42 is simultaneously sputtered by Ar plasma, so that the deposited DLC layer collapses. The collapsed DLC becomes flakes F, scatters around, adheres to the DLC film forming surface of the opposing base material 2, and is fixed.

At the time of film formation, the plurality of base materials 2 (with a base formed as necessary) are rotatably erected on the peripheral edge of the base material support base at equal intervals. Then, at the time of film formation, the vacuum chamber 41 and the base material 2 are rotated. As a result, all the base materials 2 can face the sputtered cathode 42 at a fixed distance, a fixed time, and at equal intervals. Further, the entire side surface of the base material 2 can be opposed to the sputtered cathode under the same conditions.

The flakes F adhering to and fixed on the surface of the DLC film are then removed by polishing the surface of the DLC film by a method such as wrapping, and holes are formed in the marks.

3. 3. Comparison of shape with conventional DLC film In the DLC film of the present embodiment, as described above, when the film is viewed from the surface, the individual pores are not circular but irregular, and one or more corners are formed. It has a feature that the size of the hole is large. In order to clarify this, a comparison with a conventional DLC film was performed. 6 and 7 show surface SEM images of a conventional DLC film. FIG. 6 is an SEM image of the surface of a DLC film formed by arc vapor deposition and FIG. 7 is a plasma CVD film, and the surfaces of Sample B and Sample C in Examples described later are photographed, respectively.

As shown in FIG. 6, the surface of the DLC film formed by arc vapor deposition has a large number of pores, but its shape is circular, has no corners, and is small in size. As shown in FIG. 7, the surface of the DLC film formed by plasma CVD has a very small number of holes, though not absent, and the shape is circular, has no corners, and is small in size.

4. Preferred Embodiment In the present embodiment, the above-mentioned DLC film and the film forming method thereof preferably take the following embodiments.

(1) Preferred Form in DLC Film The DLC film preferably takes each of the following embodiments.

(A) Hole size As for the size of the hole H, the length of the longest portion is preferably 10 to 200 μm. This allows the holes to function properly as a lubricant reservoir.

(B) Ratio of pores to the film surface The ratio (area ratio) of holes H to the film surface is preferably 7 to 23%. As a result, the lubricant can be appropriately supplied from the holes as the lubricant reservoirs. The ratio of the hole H to the film surface is determined by, for example, the ratio of the number of pixels of the hole H to the total number of pixels of the imaging data taken by the microscope on the film surface.

(C) Surface Roughness The arithmetic average roughness Ra of the surface of the DLC film is preferably 0.01 to 0.07 μm. As a result, the sliding characteristics of the DLC film can be appropriately exhibited. The "arithmetic mean roughness Ra" refers to the arithmetic mean roughness in the surface roughness measured by a method according to JIS B601: 2013.

(D) Maximum valley depth of the hole The maximum valley depth Rv of the hole is preferably 0.04 to 0.23 μm. This allows the holes to function properly as a lubricant reservoir. The "maximum valley depth Rv" refers to the maximum valley depth in the surface roughness measured by a method according to JIS B601: 2013.

(E) Pore oil pool depth The hole oil pool depth Rvk is preferably 0.03 to 0.35 μm. This allows the holes to function properly as a lubricant reservoir. The "oil pool depth Rvk of the hole" refers to the depth of the protruding valley portion in the surface roughness measured by the method according to JIS B601: 2013.

(F) Structure of film In the DLC film, a metal base layer containing chromium (Cr) or tungsten (W) is formed as an adhesive layer on a substrate, and then chromium (Cr) or tungsten (C) or tungsten () formed as an intermediate layer. It is preferably formed on a metal-containing hard carbon layer containing W). This makes it possible to improve the adhesion between the DLC film and the base material.

(G) Base material In the present embodiment, as the base material, a base material composed of a base material main body portion and a Cr or W metal base layer formed on the base material main body portion is used. Is preferable. As a result, the DLC film can be brought into close contact with the base material. The thickness of the metal base layer is preferably about 0.2 to 0.7 μm, and can be formed by, for example, a sputtering vapor deposition method or an arc vapor deposition method.

(2) Preferred Form in the DLC Film Filming Method The DLC film forming method preferably takes each of the following embodiments.

(A) Formation of DLC film As described above, the DLC film is formed on a metal-containing hard carbon layer containing chromium (Cr) or tungsten (W) formed as an intermediate layer on the substrate. Is preferable. FIG. 8 is a diagram illustrating the formation of a two-layer structure of the surface layer (DLC film) and the intermediate layer. In FIG. 8, 11 is a surface layer and 12 is an intermediate layer.

When forming the DLC film 1, the flakes F are fixed to the DLC film 1 at the time of film formation, and after the film formation, the flakes 1 are separated from the DLC film to form the pores H. At this time, it is preferable to form the DLC film 1 in the order of the intermediate layer 12 and the surface layer 11 by the following methods.

First, the intermediate layer 12 is formed by a composite process in which a film formation by a plasma CVD method using a hydrocarbon as a raw material and a film formation by a sputtering method using Cr or W as a sputtering cathode are performed in parallel in the same vacuum chamber. Form.

When Cr or W is used for the sputtered cathode, the frequency of flake generation increases dramatically, so that more flake F can be fixed, and as a result, the pores H can be efficiently distributed at a preferable density. Can be done.

Next, the surface layer 11 is formed by a composite process in which a film formation by a plasma CVD method using a hydrocarbon as a raw material and a film formation by a sputtering method using solid carbon as a sputtering cathode are performed in parallel in the same vacuum chamber.

The sputtering method using graphite as a solid raw material has the disadvantage that the film forming method is slow, but when a hydrocarbon gas is passed through this furnace, a hard carbon film can be formed by the same principle as the plasma CVD method, and the hydrocarbon gas can be formed. The film formation speed is significantly improved compared to the sputter vapor deposition method that does not flow.

Therefore, by forming a hard carbon film by adopting a composite process in which the sputtering method and the plasma CVD method are used in combination, the film forming speed can be improved as compared with the case where each method is used alone. ..

(B) Formation of holes It is preferable that the holes H are formed by polishing the formed DLC film 1 by, for example, a lapping process. As a result, the flakes F adhering to the surface can be efficiently separated. Specifically, brush wrap, film wrap, barrel polishing and the like are applied.

(C) Control of pore area ratio There is a correlation between the abundance of flakes F, that is, the area ratio of flakes F to the film surface and the film thickness of the DLC film. FIG. 9 shows the relationship between the abundance of flakes F obtained from imaging data of the DLC film surface having a film thickness of 0.8 μm, 1.4 μm, 2.0 μm, and 3.8 μm using a microscope and the film thickness of the DLC film. It is a figure which shows. From FIG. 9, it can be seen that there is a high correlation between the abundance of flakes F and the film thickness of the DLC film.

Then, as described above, since the detachment marks of the flakes F are the holes H, the area ratio of the holes H can be adjusted to a desired value by controlling the film thickness. FIG. 10 is an image taken by a microscope of the film surface after the formation of pore H in the DLC film, and (a) to (d) have thicknesses of 0.8 μm, 1.4 μm, and 2.0 μm, respectively. It is a photograph image of the DLC film of 8 μm. In these imaging data, the area ratio of the holes H can be adjusted by controlling the film thickness, and the area ratio of the holes H is preferable by controlling the film thickness to 0.8 to 3.8 μm. It shows that it can be adjusted to 7 to 23%.

(D) Control of film surface roughness There is also a correlation between the arithmetic mean roughness Ra of the DLC film, the maximum valley depth Rv, the oil pool depth Rvk, and the film thickness of the DLC film. 11 to 13 show the arithmetic mean roughness Ra, the maximum valley depth Rv, and the oil pool depth Rvk of the DLC film having a film thickness of 0.8 μm, 1.4 μm, 2.0 μm, and 3.8 μm, respectively. It is a figure which shows the relationship of thickness. These figures show that it is possible to adjust the arithmetic mean roughness Ra, the maximum valley depth Rv, and the oil sump depth Rvk by controlling the film thickness, and based on these correlations. Therefore, the arithmetic mean roughness Ra, the maximum valley depth Rv, and the oil pool depth Rvk can be adjusted to desired values.

(E) Pretreatment of the base material When forming the DLC film, the surface of the base material is previously exposed to plasma of at least one gas selected from the group consisting of hydrogen gas, oxygen gas and noble gas. It is preferable to clean with. As a result, impurities on the surface of the base material can be removed to maintain a clean state, and the adhesion between the DLC film and the base material can be improved.

According to this method, since the substrate after the pretreatment can be transferred to the film formation without being taken out from the vacuum chamber, contamination of the substrate surface can be reliably prevented, which is preferable. Further, it is efficient because the pretreatment and the film formation can be performed continuously.

Next, the present invention will be described in more detail based on Examples.

In this example, a sample in which three types of DLC films were formed on a substrate was prepared, and the peel resistance of each film was evaluated.

[1] Preparation of sample 1. Substrate As shown in Table 1, a substrate made of SCM415 carburized (HRC60) having a diameter of 30 mm and a thickness of 3 mm was prepared.

2. 2. Formation of DLC film (1) Sample A
Sample A is a sample in which a DLC film is formed on the above-mentioned substrate by using a sputtering vapor deposition method and a plasma CVD method in combination according to the present invention. Specifically, a film was formed with the following settings to form a film thickness of 0.8 μm on the substrate.
Cleaning process: Ar150ccm, pressure 0.4Pa
Filament emission current 8A
Board bias voltage 800V
Metal base (Cr) process: Ar250ccm, pressure 0.9Pa
Spatter power output 5kW
Board bias voltage 150V
Cr-containing DLC (intermediate layer) process: Ar500ccm, C2H _{2 10-200ccm}
Pressure 0.8-1.0Pa
Spatter power output 3kW
Board bias voltage 100-600V
DLC process: _Ar250ccm , C2H2 _100ccm
Pressure 0.5Pa
Spatter power output 4kW
Board bias voltage 550V

(2) Sample B
Sample B is a sample in which a DLC film is formed on the above-mentioned substrate by an arc vapor deposition method. Specifically, a film was formed with the following settings to form a film thickness of 1.0 μm on the substrate.
Cleaning process: Ar200ccm, pressure 1.0Pa
Board bias voltage 1000V
Metal substrate (Cr) process: Ar10ccm, pressure 0.1Pa
Arc current 45A
Board bias voltage 400V
DLC process: Ar10ccm, pressure 0.1Pa
Arc current 45A
Board bias voltage 45V

(3) Sample C
Sample C is a sample in which a DLC film is formed on the above-mentioned substrate by plasma CVD. Specifically, a film was formed with the following settings to form a film thickness of 3.0 μm on the substrate.
Cleaning process: Ar50ccm, pressure 0.2Pa
Discharge current 20A, electromagnetic coil energization current 5A
Board bias voltage 500V
Sputtering process: Ar50ccm, pressure 0.3Pa
Discharge current 20A, electromagnetic coil energization current 0A
Board bias voltage 100V
Time 40 minutes Si-containing DLC process: Ar50ccm, _TMS100ccm , C2H2 _100ccm
Pressure 0.1Pa
Discharge current 20A, electromagnetic coil energization current 5A
Board bias 500V
DLC process: Ar50ccm, C2H2 _100ccm , pressure _0.1Pa
Discharge current 20A, electromagnetic coil energization current 5A
Board bias 500V

[2] Evaluation of peeling resistance Next, the adhesion of the DLC film of each sample was evaluated by a rolling test (thrust test) using a bearing.

1. 1. Test method The test was carried out using the thrust tester shown in FIG. Specifically, after supplying a predetermined amount of lubricant to the surface of the DLC film of each sample 54 on which the DLC film is formed, the steel ball 51 mounted on the raceway ring 52 is pressed with a constant load to press the raceway ring 52. This was done by rolling and orbiting along the same orbit and repeatedly applying a predetermined number of times to the orbiting portion of the steel ball 51. The details of the test conditions are shown in Table 1.

2. 2. Test Results (1) Surface Condition During Film Formation As SEM images showing the surface condition of each sample during film formation, the surface condition of sample A is shown in FIG. 1, sample B is shown in FIG. 6, and sample C is shown in FIG. 7.

From FIG. 1, it can be seen that in the case of the combined use of the arc vapor deposition method and the plasma CVD method, holes having one or more corners are formed. From FIG. 6, it can be seen that in the case of the arc vapor deposition method, small granular (spherical) dents having no corners are formed. Further, from FIG. 7, it can be seen that in the case of the plasma CVD method, smaller granular (spherical) dents than those in FIG. 6 are formed.

(2) Thrust test results The results of the thrust test are shown in FIG. FIG. 15 is a surface SEM image of the orbital portion of each sample after the thrust test.

From FIG. 15, in the case of sample A as an example, it was confirmed that the DLC film did not peel off in both the 225,000 times fatigue test and the 1.26 million times fatigue test. Such excellent fatigue resistance was obtained because the lubrication function by the lubricant was maintained during the fatigue test and the friction due to rolling contact was suppressed to a low level. As a result, the DLC films and the DLC film and the base material were obtained. This is because the stress generated at the interface with and is suppressed.

On the other hand, in the case of sample B, peeling did not occur in the 225,000 times fatigue test, but in the 1.26 million times fatigue test, peeling occurred on the entire circumference of the DLC film in the orbital portion.

In the case of sample C, the DLC film had already peeled off in a part of the orbital portion in the 225,000 times fatigue test, and peeled off in the entire circumference of the DLC film in the orbital portion in the 1.26 million times fatigue test.

As a result of the above, it can be confirmed that a film having excellent performance can be obtained by forming a DLC film having one or more corners in the pores by using the arc vapor deposition method and plasma CVD in combination according to the present invention. rice field.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. It is possible to make various modifications to the above embodiments within the same and equal range as the present invention.

1 DLC film 2 base material 3 base material 4 film forming equipment 11 surface layer 12 intermediate layer 41 vacuum chamber 42 sputter cathode 51 steel ball 52 track ring 53 oil 54 sample F carbon flakes (flakes)
H hole

Claims (12)

A hard carbon film that covers at least part of the contact area of the lubricant on the substrate.
A hard carbon film characterized in that a plurality of holes having one or more corners are formed on the surface. The hard carbon film according to claim 1, wherein the length of the longest portion of the hole is 10 to 200 μm. The hard carbon film according to claim 1 or 2, wherein the ratio of the pores to the film surface is 7 to 23%. The hard carbon film according to any one of claims 1 to 3, wherein the arithmetic average roughness Ra of the surface is 0.01 to 0.07 μm. The hard carbon film according to any one of claims 1 to 4, wherein the maximum valley depth Rv of the pores is 0.04 to 0.23 μm. The hard carbon film according to any one of claims 1 to 5, wherein the oil reservoir depth Rvk of the pores is 0.03 to 0.35 μm. It is formed on the intermediate layer formed on the base material, and is formed on the intermediate layer.
The hard carbon film according to any one of claims 1 to 6, wherein the intermediate layer is a metal-containing hard carbon layer containing chromium or tungsten. One of claims 1 to 7, wherein the base material is composed of a base material main body portion and a chromium or tungsten metal base layer formed on the base material main body portion. The rigid carbon film described in the section. The method for forming a hard carbon film according to any one of claims 1 to 6.
A hard carbon film forming step of forming a hard carbon film on the base material,
It is provided with a pore forming step of forming a plurality of the pores with respect to the formed hard carbon film.
The hard carbon film forming step is a composite process step in which a film formation by a plasma CVD method using a hydrocarbon as a raw material and a film formation by a sputtering method using solid carbon as a sputtering cathode are performed in parallel in the same vacuum chamber. And
The hard carbon film is characterized in that the pore forming step is a step of forming the pores by polishing and removing carbon flakes generated from the sputtered cathode and fixed on the surface of the hard carbon film. Film formation method. The method for forming a hard carbon film according to claim 7.
An intermediate layer forming step of forming a metal-containing hard carbon layer containing chromium or tungsten as an intermediate layer on the substrate,
A hard carbon film forming step of forming a hard carbon film on the intermediate layer,
It is provided with a pore forming step of forming a plurality of the pores with respect to the formed hard carbon film.
The intermediate layer forming step is a composite process step in which a film formation by a plasma CVD method using a hydrocarbon as a raw material and a film formation by a sputtering method using chromium or tungsten as a sputtering cathode are performed in parallel in the same vacuum chamber. And
The hard carbon film forming step is a composite process step in which a film formation by a plasma CVD method using a hydrocarbon as a raw material and a film formation by a sputtering method using solid carbon as a sputtering cathode are performed in parallel in the same vacuum chamber. And
The hard carbon is characterized in that the pore forming step is a step of forming the pores by removing carbon fragments generated by the collapse of the carbon film adhering to the surface of the sputtered cathode in the intermediate layer forming step. Film forming method. The hard carbon according to claim 9 or 10, wherein a base material forming step for forming the base material by forming a metal base layer of chromium or tungsten is provided on the base material main body portion. Film forming method. Claims 9 to 11 are characterized in that the surface of the substrate is cleaned in advance by exposing it to plasma of at least one gas selected from the group consisting of hydrogen gas, oxygen gas and noble gas. The method for forming a hard carbon film according to any one of the above items.

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