JP2000320674A - Low friction material and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low friction material to combine lowness of a friction factor under non-lubrication with lowness of a friction factor under lubrication, and to provide a manufacturing method of the low friction friction material. SOLUTION: By removing a part of a carbon film 3 after the carbon film 3 is formed on the surface of an iron base material 2, or by forming the carbon film 3 in a state that a masking is previously applied on the surface of the base material 2, the base material 2 is exposed from a friction surface togetherwith the carbon 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material applied to a sliding portion of various mechanical structural members, and more particularly, to a friction material having a non-lubricated coefficient of friction comprising an iron-based substrate and a carbon film. The present invention relates to a low-friction friction material capable of achieving both a low friction coefficient and a low friction coefficient under lubrication and achieving a synergistic effect with an extreme pressure additive in a lubricating oil, and a method for producing such a low-friction friction material. Things.

[0002]

There have been many studies on carbon films. For example, plasma C
Hard amorphous carbon (a-C) by VD or PVD ion plating, ion beam evaporation, etc.
And carbon films such as diamond, hydrogenated carbon (a-C: H), metal-containing amorphous carbon (a-MeC: H), and diamond-like carbon (DLC). Many proposals for improvement have been made (for example, see JP-A-6-13).
No. 8035).

[0003] Since surface treatment using these carbon films is expected to have various uses, extensive research has been conducted so far, and in recent years, cost problems have been raised due to the development of film forming apparatuses and the like. Since it is gradually being eliminated, the range of application has been greatly expanded industrially.

[0004] The most significant reasons are the solid lubricity and hardness of the carbon film itself. That is,
When a surface treatment with a carbon film is performed on the friction surface, an effect of lowering the friction coefficient on the friction surface and improving the wear resistance is obtained. The surface hardness is also very high by Vickers hardness of 1000. In many cases, the carbon film including the DLC film has a friction /
It can be said that the surface treatment material has extremely attractive characteristics from the viewpoint of wear characteristics.

Since these carbon films have solid lubricating properties, they have attracted attention for use in non-lubricating environments such as space-related and device-related applications. However, they have been used in lubricating oils because of their excellent friction / wear characteristics. It is expected that the use as a surface treatment for such parts will be expanded in the future. In other words, when the contact portion is viewed microscopically even in lubricating oil,
There is also a situation called a metal contact where the solids that rub against each other are in direct contact with each other without the intermediary of lubricating oil. Therefore, even under lubrication, the effect of reducing friction utilizing the solid lubricity of the carbon film can be expected. The idea is to apply this to parts in lubricating oil, but when sliding in lubricating oil, an oil film is generated between the contact parts due to the effect of fluid pressure, and the ratio of so-called metal contacts is There is a problem that there is a limit to the reduction of friction by simply applying a conventional carbon film, as compared with the conventional sliding.

On the other hand, lubricating oils used in internal combustion engines, transmissions, and the like have been variously improved to improve the friction / wear characteristics of sliding parts. One of them is extreme pressure. Development of additives. In particular, metallic extreme pressure additives form a reactive coating when sliding against a friction surface mainly composed of iron, and the coating improves the friction / wear characteristics. In particular, with a molybdenum-based extreme pressure additive, MoS ₂ known as a solid lubricant is generated on the friction surface during sliding, and the friction is greatly reduced. However, if the iron-based substrate is covered with a carbon film, there is a problem that a reaction film is not generated and such an effect cannot be obtained. However, in addition to the friction / wear characteristics in a non-lubricated environment, the problem has been to improve the friction / wear characteristics under lubrication.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in a friction material using a conventional carbon film, and has a low friction coefficient under no lubrication and a low friction coefficient under lubrication. It is an object of the present invention to provide a low friction friction material having low height and a method of manufacturing such a low friction friction material.

[0008]

A wide range of friction tests using various combinations of lubricating oils and sliding conditions have been performed, and various analyzes have been performed on carbon films. On the other hand, it has been confirmed that even if a surface treatment is performed with a carbon film, the expected effect of reducing friction may not always be obtained as compared with a conventional iron-based material having no surface treatment.

That is, when a lubricating oil composed of only a base oil is used, the lubricating oil contains an extreme pressure additive such as a molybdenum-based additive, although the frictional reduction effect of the carbon film is obtained even under lubrication. When lubricating oil was used, the effect of the additive was not always able to obtain the same effect of reducing friction as compared with the case of using only iron without surface treatment.

[0010] In order to elucidate such a phenomenon, a surface analysis of the friction surface after a friction test was carried out. As a result, when the sliding surface was made of only iron, a reaction film formed of a molybdenum-based extreme pressure additive was observed. MoS ₂ , a kind of solid lubricant
Although the presence of (molybdenum disulfide) was confirmed, when the carbon film was coated on the friction surface, adsorption of the constituent elements of the additive was hardly recognized on the friction surface after the test, and the formation of a reaction film was observed. I could not confirm. Similarly, in tests with lubricating oils containing zinc-based extreme pressure additives, which are widely added to mechanical lubricating oils as anti-wear agents, when the sliding surface is iron, a reactive coating is also observed. On the other hand, when the carbon film was used as the friction surface, no reaction film was observed, and it was presumed that the original action of the extreme pressure additive was suppressed by covering the iron film with the carbon film.

On the basis of the above results, the present inventors have exposed a base material made of an iron-based material together with a carbon film to a friction surface. As a result, a reaction film can be formed on the friction surface. The effect of the solid lubricating property of the film and the effect of the reaction film based on the additive in the lubricating oil are compatible, and a synergistic effect is obtained in which each effect complements both effects.
It has been found that a friction material having both a low coefficient of friction under no lubrication and a low coefficient of friction under lubrication can be obtained.

The present invention is based on such a finding, and a low friction friction material according to claim 1 of the present invention comprises a base material made of an iron-based material and a carbon film formed on the surface thereof. The structure is such that the base material is exposed together with the carbon film on the friction surface, and such a structure in the low friction friction material is a means for solving the above-mentioned conventional problems.

[0013] As an embodiment of the low friction friction material according to the present invention, in the friction material according to claim 2, the exposed area of the iron-based substrate on the friction surface can be 5% or more and less than 70%. The low friction friction material according to claim 3 is desirably used together with a lubricating oil containing a molybdenum-based extreme pressure additive. Further, as an embodiment, the low friction friction material according to claim 4, wherein the exposed area of the iron-based base material on the sliding surface is set to 20% or more and less than 70%, so that the valve lifter of the internal combustion engine or the camshaft and the valve lifter The low friction friction material according to claim 5, wherein the exposed area of the iron-based base material is set to 5% or more and less than 50%, and the low friction friction material according to claim 5 is provided with a bore surface of a cylinder block in a piston ring of an internal combustion engine. Claim 6
The low friction friction material according to the above can be applied to the piston ring and the sliding surface of the cylinder block bore surface of the internal combustion engine with the piston by similarly setting the exposed area of the iron-based base material to 5% or more and less than 50%.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a low friction friction material, comprising: forming a carbon film on a surface of a base material made of an iron-based material; The structure is such that the base material is exposed together with the film, and such a structure in the method for producing a low friction friction material is characterized as a means for solving the above-mentioned conventional problems.

As an embodiment of the method of manufacturing a low friction friction material according to the present invention, in the manufacturing method according to claim 8, after forming a carbon film, one of the carbon films is formed by laser texturing, lithography or dry etching. In the manufacturing method according to claim 9 as an embodiment, after forming irregularities on the surface of the iron-based base material in advance, forming a carbon film, and flattening the carbon film on the friction surface. In addition, it is characterized in that the iron base material is exposed. At this time, as described in claim 10, the maximum value of the height difference of the unevenness is to form a wave shape of 0.5 μm or more and less than 10 μm on the surface of the base material. As described above, it is desirable that the pitch of the waves be in a range of 10 μm or more and less than 2 mm.

Further, according to a method of manufacturing a low friction friction material according to claim 12 of the present invention, after partially masking the surface of the iron-based substrate, a carbon film is formed and the friction surface is formed together with the carbon film on the friction surface. It is characterized in that the iron base material is exposed.

In the method of manufacturing a low friction friction material, when forming a carbon film, the method of claim 13 is preferable.
, A CVD method or a PVD method can be applied.

[0018]

The mechanism of friction reduction under lubrication of the low friction friction material according to the present invention is considered as follows.

That is, in the sliding in the lubricating oil, there occurs a situation of a metal contact in which the sliding member is in direct contact with the frictional portion, but by exposing the iron-based material base together with the carbon film on the friction surface. In the sliding part, in addition to the solid lubrication by the carbon film, a reaction film of the additive is formed in the part where the base material is exposed on the friction surface, and the solid lubrication by this film is obtained. For example, the friction coefficient of MoS ₂ alone is generally considered to be lower than 0.01, which is lower than the friction coefficient reported for the carbon film and has a larger friction coefficient than the carbon film alone. A reduction effect is obtained.

However, since the reaction film due to the additive is generated during sliding, the state of the reaction film greatly depends on the lubrication conditions at the friction site, the sliding conditions, the deterioration of the additive, and the like. . Quantitative factors, such as the thickness and distribution of the reaction film, which are thought to affect the friction characteristics, are determined by the balance between generation and wear. Since the formation of the film is due to a chemical reaction, a load such as a temperature or a pressure required for the chemical reaction to a certain level or more, or a load such as a sliding speed is required. Also, under conditions where the wear rate exceeds the generation rate, such as when the load is too large or when the supply amount of the lubricating oil is extremely small, the reactive coating does not exist stably, and reduction of friction by the reactive coating cannot be expected. .

As described above, the action of the additive by the reaction film is different from the action of the carbon film existing from the beginning, and is not always uniform depending on the conditions. Coexistence is considered necessary. The surface hardness of the carbon film is often much higher than 1000 in Vickers hardness, and exhibits excellent wear resistance in combination with low friction characteristics. That is, in the low friction friction material according to the present invention, the carbon film plays a role as a strong matrix, which leads to indirect suppression of abrasion of the base material exposed on the friction surface.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The low friction friction material according to the present invention comprises a substrate made of an iron-based material and a carbon film on the surface thereof, and has a structure in which the substrate is exposed together with the carbon film on the friction surface. Therefore, low friction characteristics (non-lubricating environment) based on the solid lubricity inherent in the carbon film, and low friction due to the reaction product between the extreme pressure additive contained in the lubricating oil and the iron in the base material exposed on the friction surface The characteristics (lubricating environment) are compatible with each other, and a significant friction reduction effect can be obtained especially by synergistic action with additives in the lubricating oil. Is, for example, claim 2.
As described in above, it is desirable that the content be 5% or more and less than 70%. That is, when the exposed area of the iron-based base material is less than 5%, the reaction between the iron contained in the base material and the additive in the lubricating oil becomes insufficient, and a reaction film cannot be obtained. When the effect of reducing the friction in the inside becomes insufficient and the exposed area becomes 70% or more, the exposed area of the carbon film becomes relatively small and the friction reduction without lubrication due to the solid lubricity of the carbon film. The effect cannot be obtained.

Further, since a very remarkable effect of reducing friction can be obtained as the lubricating oil, it is desirable to use the lubricating oil together with the lubricating oil containing a molybdenum-based extreme pressure additive. As such a molybdenum-based extreme pressure additive, for example, molybdenum dithiocarbamate (MoDTC) can be used. The additive functions as a solid lubricant due to a chemical reaction with iron contained in the base material on the friction surface during sliding.
A film containing S ₂ is generated, and a remarkable effect of reducing friction is obtained.

The lubrication condition in which the effect of the low friction friction material according to the present invention is most remarkable is use in a boundary lubrication region. In an engine part (internal combustion engine), a camshaft and a valve lifter or a camshaft and a valve are used. The sliding between the lifter and the shim inserted for adjusting the gap or the sliding between the cylinder bore and the piston or the piston ring corresponds to this. Therefore, such a low friction friction material can be used as a valve lifter or shim of an internal combustion engine as described in claim 4, and a sliding surface of the piston ring with the cylinder bore as described in claim 5. Further, the present invention can be applied to a sliding surface between a piston ring and a piston in a cylinder bore.

At this time, in the case of sliding between the camshaft and the valve lifter or the shim, since the lubricating oil is more supplied than in the case of sliding between the cylinder bore and the piston ring, the lubricating oil and the additive in the lubricating oil are not supplied. Since the effect of forming a film by the reaction can be expected to be further increased, the exposed area ratio of the iron-based substrate is preferably set to 20% or more and less than 70%.
On the other hand, in the case of sliding between the cylinder bore and the piston ring, the lubricating oil supplied to the sliding portion is sprayed from below the piston, so that the amount of the lubricating oil is smaller than that of sliding between the cam and the lifter or the shim, and furthermore, the combustion is reduced. Since the surface temperature rises considerably near the chamber, the effect of solid lubrication by the carbon film on the friction surface becomes more dominant than the reaction film with the additive in the lubricating oil. Therefore, it is desirable that the exposed area ratio of the base material on the friction surface of the sliding portion between the cylinder bore, the piston ring, and the piston is 5% or more and less than 50%.

Such a low friction friction material is formed, for example, by forming a carbon film on the surface of a base material made of an iron-based material such as steel or a casting after forming a carbon film on the surface of the base material by, for example, machining. The carbon film formed on the base material is partially removed by lapping, laser texturing, lithography or dry etching as defined in claim 8, thereby forming a base with the carbon film on the friction surface. It can be manufactured by exposing a part of the material.

Alternatively, the surface of the substrate may be partially masked prior to film formation to prevent the formation of a carbon film on the masked portion, as described in claim 12. It is also possible to expose a part.

On the other hand, when applied to a part where the sliding pressure is severe due to a large surface pressure and a sliding speed applied to the friction surface,
In some cases, it is necessary to reduce the level difference between the surface of the carbon film and the surface of the base material. From such a viewpoint, the surface of the base material may be subjected to, for example, machining or chemical polishing. , Electrolytic polishing, or electric discharge machining, etc., to give a carbon film after giving irregularities in advance, and then to expose the base material to the friction surface without any step by, for example, machining it into a flat surface. it can.

The irregular shape at this time is described in claim 1
As described in 0 and 11, the maximum value of the height difference between the convex portion and the concave portion is in a range of 0.5 μm or more and less than 10 μm,
It is desirable that the pitch is in the form of a ripple having a range of 10 μm or more and less than 2 mm. That is, the maximum value of the unevenness height difference is regulated by the thickness of the carbon film formed by performing planar processing after film formation. The thickness of the carbon film is set according to the film forming method and the film forming conditions, and the thickness of the carbon film generally used industrially is about 10 μm or less in most cases. Therefore, when the maximum value of the irregularities becomes 10 μm or more, it is necessary to form a carbon film that is thicker. When the carbon film becomes thicker, the residual stress generated after the film formation tends to increase. If the maximum value of the irregularities is less than 0.5 μm, it is difficult to adjust the exposed area of the base material, and the thickness of the carbon film remaining on the base material becomes thin. And the possibility of peeling occurs. If the pitch of the irregularities is less than 10 μm, it is similarly difficult to adjust the exposed area of the base material. There is a tendency that the carbon film having a lower concave portion is excessively polished, and it is difficult to obtain a desired area ratio of the carbon film and the base material.

Further, as a method for forming a carbon film, a CVD method (chemical vapor deposition method) or a PVD method (physical vapor deposition method) can be applied. That is, the carbon film itself can be formed by any method. When the PVD method is applied, graphite is often used as a target, so that the carbon film is composed of only carbon. In the CVD method, film formation by plasma CVD is mainstream, and a hydrocarbon-based gas is often used as a raw material. For this reason, hydrogen is mixed during film formation, and hydrogen is contained in a carbon film. Each carbon film shows good solid lubricity under no lubrication and has high hardness, which is suitable for the low friction friction material according to the present invention.

[0031]

The low friction friction material according to claim 1 of the present invention has a carbon film on the surface of a substrate made of an iron-based material, and the carbon film and the substrate are exposed on the friction surface. Therefore, the carbon film can have both low friction characteristics due to solid lubricity of the carbon film and low friction characteristics due to a reaction product between the extreme pressure additive contained in the lubricating oil and iron in the base material. In addition, the synergistic effect with the additive in the lubricating oil brings about an extremely excellent effect that the friction / wear characteristics can be greatly improved.

[0032] In the friction material according to claim 2 as an embodiment of the low friction friction material according to the present invention, the exposed area of the iron base material to the friction surface is in the range of 5% to less than 70%. When the exposed area of the iron base material is 5% or more, the reaction between the iron in the base material and the additive in the lubricating oil is not excessive or insufficient, and the exposed area of the carbon film on the friction surface is improved. It is also possible to balance the friction reduction effect in the lubricating oil by the reaction film and the friction reduction effect in the non-lubricated state by the solid lubricating property of the carbon film in a balanced manner. In the related low friction friction material, since it is used together with a lubricating oil containing a molybdenum-based extreme pressure additive as an additive, MoS is caused by a chemical reaction with iron contained in the base material during sliding. 2 is generated, and a particularly remarkable friction reduction effect can be obtained.

Further, as a preferred embodiment, the low friction friction material according to claim 4 is applied to a valve lifter or a shim of an internal combustion engine, and has an exposed area of a friction surface of an iron-based substrate in a range of 20% or more and less than 70%. Therefore, the effect of reducing friction in the lubricating oil abundantly supplied to the sliding surface can be maximized, and the low friction friction material according to claim 5 is capable of reducing the friction between the piston bore and the cylinder bore. It is applied to the sliding surface, and the exposed area of the iron-based substrate to the friction surface is in the range of 5% or more and less than 50%. The lubricating property can be utilized, and the low friction friction material according to claim 6 is applied to a sliding surface between a piston ring and a piston in a cylinder bore, and the friction of an iron-based substrate is improved. Similarly more than 5% of the exposed area of the surface 5
Since the range is less than 0%, an excellent effect that the solid lubricity of the carbon film can be maximized on the sliding surface where the supply of the lubricating oil is relatively small is brought about.

In the method of manufacturing a low friction friction material according to claim 7 of the present invention, the carbon film formed on the surface of the base material made of an iron-based material is partially removed to remove the base material containing iron. Since the surface is exposed to the surface, an extremely excellent effect that the low friction friction material according to the present invention can be easily obtained is obtained.

According to an embodiment of the method for producing a low friction friction material according to the present invention, the carbon film on the substrate is partially removed by laser texturing, lithography or dry etching. So that processing accuracy is excellent,
It is possible to easily obtain a low friction friction material having a desired exposed area according to the application, and in the method for manufacturing a low friction friction material according to claim 9 as an embodiment, unevenness is previously formed on the surface of the base material. After the carbon film is formed, the carbon film on the surface of the base material is planarized to expose the base material on the friction surface, so that there is a step between the carbon film surface and the base material surface. A non-sliding surface can be obtained, and it can be applied to a part where the surface pressure and the sliding speed are large and the sliding conditions are severe.

According to the tenth and eleventh aspects of the method for producing a low friction friction material according to the ninth aspect, the unevenness formed on the surface of the base material is made different from the height difference. Since the maximum value is 0.5 μm or more and less than 10 μm, and the pitch is in a range of 10 μm or more and less than 2 mm, the surface of the base material is exposed at a desired exposed area ratio without causing carbon film peeling or residual stress. It can be exposed from the carbon film.

Further, in the method of manufacturing a low friction friction material according to the twelfth aspect of the present invention, the carbon film is formed while partially masking the surface of the substrate made of an iron-based material. Therefore, it is possible to expose a part of the base material containing iron from between the carbon films on the friction surface, and it is possible to obtain an extremely excellent effect that the low friction friction material according to the present invention can be easily obtained.

In the method for producing a low friction friction material according to the thirteenth aspect of the present invention, the carbon film is formed on the surface of the base material by a CVD method or a PVD method. A carbon film exhibiting good solid lubricity without lubrication can be obtained.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments.

Examples 1 and 2 Diamond-like carbon (DLC) was formed as a carbon film on the surface of a base material 2 made of chromium molybdenum steel SCM415 specified by JIS G 4105 by a CVD method, and then the friction surface was formed. Part of the formed carbon film 3 is removed by machining so that the exposed area ratio of the base material 2 to the whole becomes 23% and 30%, respectively, and the surface of the base material 2 is exposed on a friction surface. As a result, FIG.
The disk material (low friction friction material) 1 shown in FIG. In FIG. 1A, an intermediate layer 4 is formed between the substrate 2 of the disk material 1 and the carbon film 4.

Then, the disk material 1 obtained in this manner is replaced with steel carbon chromium bearing steel SUJ2 (JIS G48).
05), a pin / disk friction test was performed under the test conditions shown in Table 1, and a lubricating environment with a lubricating oil containing a molybdenum-based extreme pressure additive was used. And the friction coefficient was measured, and the friction characteristics of each disk material 1 were examined. Table 2 shows the results.

Examples 3 to 5 A carbon film 3 made of diamond-like carbon (DLC) was formed on the same surface of the substrate 2 as in Example 1 by the CVD method or the PVD method. By removing part of 3 by dry etching, laser texturing and lithography, respectively,
The base material 2 has a structure similar to that of FIG.
The disk materials 1 having an exposed area ratio of 55%, 63% and 45%, respectively, were obtained.

Using the disk materials 1 thus obtained, a similar pin / disk type friction test was performed, and the friction characteristics of each disk material 1 were examined. These results are also shown in Table 2.

Examples 6 to 9 The same surface of the substrate 2 as in Example 1 was subjected to electrolytic polishing, electric discharge machining,
A wave shape having irregularities of respective sizes is previously formed by chemical polishing or machining, and a carbon film 3 made of diamond-like carbon (DLC) or amorphous carbon (a-C) is formed by CVD or PVD. A film was formed. By subjecting the friction surface on which the carbon film is formed to flat processing by lapping, a flat friction surface as shown in FIG. 1B is provided, and the exposed area ratio of the base material 2 is 62% and 50%, respectively. %, 68 and 31% of the disc material 1 were obtained.

Using the disk materials 1 thus obtained, a similar pin / disk friction test was carried out, and the friction characteristics of each disk material 1 were examined. These results are also shown in Table 2.

Example 10 45% of the surface of the same base material 2 as in Example 1 was masked in advance, and then amorphous carbon (a-C)
After a carbon film 3 made of PVD is formed by a PVD method, the masking agent is removed to provide a disk having a structure similar to that shown in FIG. Material 1 was obtained.

Using the disk material 1 thus obtained, a similar pin / disk type friction test was conducted, and the friction characteristics were examined. The results are shown in Table 2.

[0048] The same base material 2 of the surface and the Comparative Example 1 was formed by CVD diamond-like carbon (DLC) as a carbon film. Then, the carbon material 3 was used as a disk material without being removed without being covered, and the same pin / disk type friction test was performed to investigate the friction characteristics. The results are shown in Table 2.

[0049]

[Table 1]

[0050]

[Table 2]

As is apparent from the results shown in Table 2, the carbon film formed on the surface of the substrate was partially removed or the carbon film formed on the surface of the substrate in which the unevenness was previously formed was removed. By processing the surface together with the base material, and further forming a carbon film on the surface of the base material that has been subjected to masking in advance, the base material surface containing iron together with the carbon film is exposed on the friction surface of the present invention. In a friction test using the low friction friction material (disk 1) according to Examples 1 to 10, a low coefficient of friction was shown both under lubrication and without lubrication. On the other hand, in the comparative example using the disk with the carbon film coated on the base material, the same performance as the low friction friction material according to the present invention under no lubrication, but under lubrication It was confirmed that a reaction film with the additive in the lubricating oil was not obtained, and the friction coefficient could not be reduced.

[Brief description of the drawings]

FIG. 1A is a schematic sectional view showing a structural example of a low friction friction material according to the present invention. (B) It is an outline sectional view showing other examples of structure of a low friction friction material concerning the present invention.

[Explanation of symbols]

 1 Low friction friction material 2 Base material 3 Carbon film

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiteru Hota 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Inside Nissan Motor Co., Ltd. Inside (72) Inventor Kunio Maki 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 3G016 BB05 BB06 CA03 DA12 EA03 EA24 FA21 3J044 AA12 AA18 BA03 BB14 BB31 BC07 DA09 EA10 4F100 AA37B AB02A BA02 DD07 EH662 EJ302 GB32 JK16 4K029 AA02 BA34 BC00 BD04 GA00 4K030 BA27 CA02 DA08 LA01 LA23

Claims (13)

[Claims] 1. A low friction friction material comprising a substrate made of an iron-based material and a carbon film formed on the surface thereof, wherein the substrate is exposed on the friction surface together with the carbon film. 2. The low friction friction material according to claim 1, wherein the exposed area of the base material on the friction surface is 5% or more and less than 70%. 3. The low friction friction material according to claim 2, which is used together with a lubricating oil containing a molybdenum extreme pressure additive. 4. The exposed area of the base material on the sliding surface is 20%.
Not less than 70% and a valve lifter of an internal combustion engine,
4. The low friction friction material according to claim 3, wherein the low friction friction material is applied to a shim inserted between the camshaft and the valve lifter. 5. An apparatus according to claim 3, wherein an exposed area of the base material is not less than 5% and less than 50%, and is applied to a sliding surface of the piston ring of the internal combustion engine with a bore surface of the cylinder block. The low friction friction material described. 6. An apparatus according to claim 1, wherein the exposed area of the base material is not less than 5% and less than 50%, and is applied to a sliding surface of the cylinder block bore surface of the internal combustion engine with the piston ring and the piston. 3. The low friction friction material according to 3. 7. A method according to claim 1, wherein after forming a carbon film on the surface of the base material made of an iron-based material, a part of the carbon film is removed to expose the base material together with the carbon film on the friction surface. A method for producing a low friction friction material according to claim 6. 8. The method for manufacturing a low friction friction material according to claim 7, wherein after forming the carbon film, a part of the carbon film is removed by laser texturing, lithography or dry etching. 9. The low friction material according to claim 7, wherein after forming irregularities on the surface of the base material in advance, a carbon film is formed, and the carbon film is exposed on the friction surface together with the carbon film. Manufacturing method of friction material. 10. The unevenness formed on the surface of the base material has a wave shape, and the maximum value of the height difference is 0.5 μm or more and 10 μm or more.
10. The method for producing a low friction friction material according to claim 9, wherein the value is less than m. 11. The method for producing a low friction friction material according to claim 10, wherein the pitch of the waves is 10 μm or more and less than 2 mm. 12. The method according to claim 1, wherein after partially masking the surface of the base material made of an iron-based material, a carbon film is formed and the base material is exposed together with the carbon film on the friction surface. A method for producing a low friction friction material according to claim 6. 13. A carbon film is formed by a CVD method or a PVD method.
3. The method for producing a low friction friction material according to any one of 2.