JP2001181044A - Carbonaceous sliding material and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a carbonaceous composite sliding material excellent in sliding characteristics and mechanical strength and formable into an optional and complicated shape. SOLUTION: This carbonaceous sliding material comprising a composite of a cluster diamond and amorphous carbon is obtained by mixing a starting raw material of the amorphous carbon with a cluster diamond powder, shaping the resultant mixture into an optional form and then baking the shaped mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a carbon-based sliding material and a method for producing the same.

[0002]

2. Description of the Related Art A sliding material made of carbon has an excellent advantage of being excellent in heat resistance, chemical resistance, and light weight. Conventional metallic and polymer sliding materials are used. It is used in an environment where high temperatures and corrosiveness are not possible. Conventional carbon sliding materials are mainly classified into glassy carbon materials and graphitic isotropic carbon materials. A sliding material made of glassy carbon exhibits excellent sliding characteristics such as a low coefficient of friction and a small specific wear, but is inferior in workability due to its high hardness and poor mechanical impact resistance. On the other hand, a sliding material made of graphite-like isotropic carbon has self-lubricating properties, but has poor mechanical strength.

Further, in conventional sliding materials made of carbon such as glassy carbon and isotropic carbon material, low speed materials set in order to alleviate defects of carbon materials having poor mechanical strength and rigidity are particularly used. Sufficient sliding characteristics have not been obtained under low load conditions. In addition, these conventional sliding members made of carbon have the disadvantage that a large amount of material is wasted because they are made by cutting from a plate-shaped body or a block-shaped body, and the manufacturing process goes through a complicated manufacturing process, which increases the cost. are doing. Moreover, it was difficult to obtain an arbitrary and complicated shape.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to have better self-lubricating properties and a lower coefficient of friction than conventional carbon materials. An object of the present invention is to provide a carbon-based sliding material that is excellent in sliding characteristics such as a small specific wear amount, excellent in mechanical shock resistance and mechanical strength, and can be formed into an arbitrary and complicated shape at a simple process at a low cost. .

A second object of the present invention is to provide a carbon-based sliding material which is superior to conventional carbon-based materials in terms of sliding characteristics such as a low coefficient of friction and a small specific wear under low-speed and low-load conditions. In a simple process at a low cost.

[0006]

Means for Solving the Problems In view of such circumstances, the present inventors have conducted intensive studies and as a result, mixed carbon powder with the starting material of amorphous carbon, formed the mixture into a required shape, and then fired. The carbon-based sliding material containing carbon powder and amorphous carbon obtained by doing the above, has excellent sliding properties, mechanical shock resistance, and the above-described problem such as being able to be manufactured in a simpler process is effectively achieved. Confirmed the fact that can be solved.

Further, it has been found that the use of a carbon powder containing a cluster diamond as the carbon powder has excellent sliding characteristics, particularly under low speed and low load conditions.
This cluster diamond is 5% by mass in the sliding material.
It is preferable that the above is included. As a starting material for the amorphous carbon, an organic substance is preferably used which shows a carbonization yield of 5% or more by firing in an inert gas atmosphere. Specifically, polyvinyl chloride, polyacrylonitrile, polyvinyl alcohol, polyvinyl chloride-polyvinyl acetate copolymer, thermoplastic resin such as polyamide, phenol resin, furan resin, imide resin, epoxy resin,
Thermosetting resin such as unsaturated polyester resin, lignin,
Cellulose, tracant gum, gum arabic, condensed polycyclic aromatic substances such as saccharides and the like in the basic structure of the molecule and natural polymer substances which are not included in the above, formalin condensates of naphthalenesulfonic acid, condensed polycyclics such as copna resin Synthetic high-molecular substances having aromatics in the basic structure of the molecule can be mentioned. The type and amount of the composition to be used are appropriately selected depending on the properties, strength, and shape of the intended sliding material, and can be used alone or in a mixture of two or more. Particularly, a furan resin, a phenol resin, It is preferable to use a thermosetting resin such as an imide resin, and the amount used is preferably 30 parts by weight or more in order to impart necessary characteristics and shape as a sliding material.

The above-mentioned carbon powder includes graphite, diamond, graphite cluster diamond, cluster diamond, fullerene, carbon black, and the like. The type and amount of the carbon powder used also depends on the characteristics, strength and shape of the intended sliding material. Can be used singly or as a mixture of two or more, but as described above, a material containing cluster diamond should be used from the viewpoint of enhancing the sliding characteristics particularly under low speed and low load conditions. Is preferred.

In the present invention, more preferably, as a starting material of the amorphous carbon, an organic substance having a carbonization yield of 5% or more by firing in an inert gas atmosphere and having excellent mechanical strength characteristics is used. Specifically, a thermosetting resin such as a phenol resin, a furan resin, an imide resin, an epoxy resin, and an unsaturated polyester resin; a formalin condensate of naphthalenesulfonic acid; and a condensed polycyclic aromatic compound such as a copna resin have a basic structure of a molecule. And synthetic high molecular substances contained therein. The type and amount of the composition used are appropriately selected depending on the properties, strength and shape of the intended sliding material.
Although a mixture of more than two kinds can be used, it is preferable to use a furan resin or a phenol resin which is liquid at normal temperature for ease of production.

[0010] The above-mentioned shaping methods include commonly used molding methods such as compression molding, transfer molding, extrusion molding, injection molding, vacuum molding and blow molding. It is preferable to appropriately select and use the mixture according to the properties and the shape of the mixture of the resin and the carbon powder (particularly, cluster diamond powder). Hereinafter, a method for producing a carbon-based sliding material according to the present invention will be described. First, a resin composition and carbon powder (cluster diamond powder) are mixed well using a mixer. The resulting mixture, the properties of the mixture,
The shaping is performed using a molding method selected according to the shaping shape. Next, the shaped body is subjected to a carbon precursor treatment, and the obtained carbon precursor is heated and heated to 1000 ° C. or higher, preferably about 2000 ° C. in an inert gas atmosphere such as nitrogen or argon or in a vacuum atmosphere. (Cluster diamond) and a carbon-based sliding material comprising amorphous carbon are obtained. When the heating rate is high, defects such as deformation of the shape of the shaped body and generation of fine cracks occur. Therefore, the heating rate is preferably 100 ° C./hour or less, preferably 50 ° C./hour or less, up to 500 ° C.

[0011]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. (Example 1) Furan resin (Hitafuran V manufactured by Hitachi Chemical Co., Ltd.)
F-303) (90% by mass) was mixed with 10% by mass of cluster diamond (average primary particle size: 50 °), mixed with a pony mixer, and formed into a film using an applicator. The film is cut into a disc shape, and the film is heated in a firing furnace in a nitrogen atmosphere up to 500 ° C. at a rate of 25 ° C./hour, and then up to 1400 ° C. at 100 ° C./hour. After holding at 3 ° C. for 3 hours, the mixture was naturally cooled to complete firing, and a sliding property test piece having a thickness of 1.0 mm was obtained.
The obtained test piece, using a pin-disk friction tester,
Combine the test piece with an R0.5 mm alumina pin,
Sliding speed 0.05-1.5m / sec, load 19.6N,
A sliding test was performed under a sliding time of 22 hours. Further, the obtained test piece is cut into a size of 50 mm in length and 10 mm in width, and the bending strength and the elastic modulus are measured using a compression tester, and the test piece is broken by dropping a 40 g iron ball. The height was measured.

The results are shown in Table 1. According to Table 1, particularly excellent frictional characteristics were obtained. (Comparative Example 1) Furan resin (Hitafuran V manufactured by Hitachi Chemical Co., Ltd.)
F-303) was mixed with 20% by mass of natural graphite fine powder (average particle size: 5 μm, manufactured by Nippon Graphite Co., Ltd.) in 80% by mass, stirred with a pony mixer, and formed into a film using an extruder. The film was shaped into a disk using a vacuum forming machine. This was sandwiched between heat-resistant ceramic plates, and the temperature was raised up to 500 ° C. at a rate of 25 ° C./hour in a vacuum firing furnace, and then raised to 1400 ° C. at 100 ° C./hour.
After holding for 3 hours, firing was completed by natural cooling to obtain a sliding property test piece having a thickness of 1.0 mm. A sliding test and an impact resistance test were performed on the obtained test piece in the same manner as in Example 1, and the results shown in Table 1 were obtained. (Comparative Example 2) Furan resin (Hitafuran V manufactured by Hitachi Chemical Co., Ltd.)
F-303) was mixed with 20% by mass of carbon black (primary particle size: 5 nm, manufactured by Mitsubishi Kasei Co., Ltd.) and mixed with a Henschel mixer, and then kneaded with a roll mixer heated to 120 ° C. The kneaded material was shaped into a disk using a compression molding machine. In a baking furnace in a nitrogen atmosphere, the temperature was raised up to 500 ° C. at a rate of 25 ° C./hour, and then up to 1400 ° C. at 100 ° C./hour, and 1400 ° C.
After holding for 3 hours, firing was completed by natural cooling to obtain a sliding property test piece having a thickness of 1.0 mm. A sliding test, a bending strength test, and a mechanical impact resistance test were performed in the same manner as in Example 1.
The results are shown in Table 1. (Comparative Example 3) Furan resin (Hitafuran V manufactured by Hitachi Chemical Co., Ltd.)
F-303) was formed into a film using a film-forming machine.
The film was cut into a disc shape, and this was heated in a firing furnace in a nitrogen atmosphere up to 500 ° C. at a rate of 25 ° C./hour,
Thereafter, the temperature was raised to 1400 ° C. at 100 ° C./hour,
After holding at 0 ° C. for 3 hours, the mixture was naturally cooled to complete firing, and a sliding property test piece having a thickness of 1.0 mm was obtained. A sliding test, a bending strength test, and a mechanical impact resistance test were performed in the same manner as in Example 1. The results are shown in Table 1. (Comparative Example 4) A block of a graphitic isotropic carbon material (manufactured by Toyo Tanso Co., Ltd.) was cut into a disc shape to obtain a sliding property test piece having a thickness of 1.0 mm. A sliding test, a bending strength test, and a mechanical impact resistance test were performed in the same manner as in Example 1. The results are shown in Table 1.

[0013]

[Table 1]

(Example 2) Furan resin (Hitafuran VF-3 manufactured by Hitachi Chemical Co., Ltd.) as a hard amorphous carbon source
03) 8% by mass of cluster diamond (average primary particle size: 50 °) was mixed with 92% by mass of the mixture, and the mixture was stirred with a pony mixer, and then formed into a film using a coating machine. The film is cut into a disc shape, and the film is heated in a firing furnace in a nitrogen atmosphere up to 500 ° C. at a rate of 25 ° C./hour, and then up to 1400 ° C. at 100 ° C./hour. ° C
After holding for 3 hours, firing was completed by natural cooling to obtain a 1.0 mm thick cluster diamond / amorphous carbon / 20/80 sliding property test piece.

[0015] The obtained test piece was tested by using a Bowden-label type pin / disk friction tester.
Slip speed 1.
7 × 10 ⁻³ m / s, 8.3 × 10 ⁻³ m / s, load 0.3
The coefficient of friction under low speed and low load conditions of 9N and 1.5N was measured. Next, a friction test was performed at a sliding speed of 100 × 10 ⁻³ m / s and a load of 9.8 N to measure the specific wear of the disk sample.

Table 2 shows the measurement results. According to this example, it was found that a sliding material having better sliding characteristics than Comparative Examples 5 and 6 described below could be obtained. Example 3 A 96% by mass furan resin (Hitafuran VF-303 manufactured by Hitachi Chemical Co., Ltd.) as a hard amorphous carbon source was added to cluster diamond (average primary particle diameter 50).
Ii) 4% by mass was mixed and the mixture was stirred with a pony mixer, and then formed into a film using a coating machine. The film was cut into a disk shape, and this was fired at 500 ° C. in a firing furnace in a nitrogen atmosphere.
Up to 25 ° C./hour at a heating rate of
The temperature was raised to 100 ° C./hour, maintained at 1400 ° C. for 3 hours, and then naturally cooled to complete the calcination, and the cluster diamond / amorphous carbon having a thickness of 1.0 mm was obtained.
Specimens of the sliding characteristics were obtained.

A sliding test was performed on the obtained test piece in the same manner as in Example 2. As a result, as shown in Table 2, according to this example, it was found that a sliding material having better sliding characteristics than Comparative Examples 5 and 6 described below could be obtained. Comparative Example 5 98% by mass of a furan resin (Hitafuran VF-303 manufactured by Hitachi Chemical Co., Ltd.) as a hard amorphous carbon source was added to cluster diamond (average primary particle size: 50).
Ii) 2% by mass was mixed and the mixture was stirred with a pony mixer, and then formed into a film using a coating machine. The film was cut into a disk shape, and this was fired at 500 ° C. in a firing furnace in a nitrogen atmosphere.
Up to 25 ° C./hour at a heating rate of
The temperature was raised to 100 ° C / hour at 100 ° C, held at 1400 ° C for 3 hours, and then cooled naturally to complete firing, and a 1.0 mm thick cluster diamond / amorphous carbon # 4/96 sliding property test piece I got

The obtained test piece was subjected to a sliding test in the same manner as in Example 2. As shown in Table 2, the sliding properties were inferior to those of Examples 2 and 3. (Comparative Example 6) Furan resin (Hitafuran V manufactured by Hitachi Chemical Co., Ltd.)
F-303) was formed into a film using a post-coating machine. The film is cut into a disc shape, and the film is heated in a firing furnace in a nitrogen atmosphere up to 500 ° C. at a rate of 25 ° C./hour, and then up to 1400 ° C. at 100 ° C./hour.
After holding at 400 ° C. for 3 hours, the mixture was naturally cooled to complete the firing, and a sliding property test piece having a thickness of 1.0 mm and comprising only amorphous carbon was obtained.

The test piece thus obtained was subjected to a sliding test in the same manner as in Example 2. However, as shown in Table 2, the sliding properties were inferior to those of Examples 2 and 3.

[0020]

[Table 2]

[0021]

The carbon-based sliding material of the present invention has excellent sliding characteristics such as a small average friction coefficient and a small specific wear under low-speed and low-load conditions compared to conventional carbon materials. In addition, in the present invention using the existing plastic molding method, an arbitrary shaped body can be obtained without processing after firing, so unlike a conventional carbon-based sliding material, it is a simple process and is inexpensive. Products.

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Claims (6)

[Claims] 1. A carbon-based sliding material consisting essentially of carbon powder containing cluster diamond and amorphous carbon. 2. The method according to claim 1, wherein the cluster diamond is 5% by mass.
The carbon-based sliding material according to claim 1, which is included. 3. The amorphous carbon is a polymer material selected from the group consisting of a thermoplastic resin, a thermosetting resin, a natural polymer and a synthetic polymer exhibiting a carbon residue yield that is not substantially zero after firing. The carbon-based sliding material according to claim 1 or 2, wherein one or a mixture of two or more thereof is used as a starting material. 4. A sliding speed of 500 × 10 ⁻³ m without lubricant.
2. The carbon-based sliding material according to claim 1, wherein the average friction coefficient is 0.1 or less under low-speed and low-load conditions of 50 / s or less and a load of 50 N or less. 5. A method for producing a carbon-based sliding material, comprising mixing a carbon powder containing cluster diamond with a starting material of amorphous carbon, shaping the mixture into an arbitrary shape, and firing. 6. The starting material is one or a mixture of two or more polymer substances selected from the group consisting of a thermoplastic resin, a thermosetting resin, a natural polymer and a synthetic polymer. A method for producing the carbon-based sliding material according to the above.