JPH0812474A - Production of carbon-sic composite material - Google Patents

Abstract

PURPOSE:To provide a new, simple and low-cost production method for the subject composite material excellent in heat resistance, non-infiltrativity and wear resistance, and also adaptable to complicated design. CONSTITUTION:A material prepared by processing a carbonaceous base material >=0.5mum in average pore radius to a product form is coated, only on specified portion(s) thereof, with a slurry prepared by mixedly suspending metallic Si powder in a resin or its solvent solution, followed by drying, curing, and baking at >=1500 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing a composite material in which only a predetermined portion of the surface of a carbon substrate has been transformed and converted into a composite material in which carbon and silicon carbide are mixed.

Such a carbon-SiC composite material is used for sliding members such as bearings, shaft shafts, which are required to have wear resistance.
It is applied to the inner wall of piston cylinders, piston rings, thrust plates, valve sliding parts, vanes, etc.

[0003]

2. Description of the Related Art The main uses of carbon products for machinery are:
The bearings are roughly classified into bearings, piston rings, seals, vanes, etc., all of which are used in a state of manual contact with a mating material. Therefore, slidability including lubricity is a very important factor for these purposes. In the case of a metal material, a lubricating oil is usually used in order to prevent obstacles such as heat generation, seizure, and power loss due to manual friction.

However, when the lubricating oil is heated to a high temperature, it flows out, evaporates and decomposes, loses fluidity at a low temperature and solidifies, and when it is used in a liquid, it is dispersed and dissolved in the liquid. It often loses its function.

Further, depending on the application, there are cases where the oil content is disliked from being mixed into the liquid, or there is a case where the oil supply is impossible due to the mechanical structure.

Since the carbon material has a weak binding force in the C-axis direction due to its structure, it has a self-lubricating property due to the sliding of the hexagonal mesh surface of the crystal, and the normal lubricating property as described above cannot be used, or oil supply is difficult. In this case, it is particularly suitable.

Further, the carbon material is excellent in corrosion resistance and heat resistance in addition to self-lubricating property, and almost satisfies the requirements as a mechanical material except that it is not as strong as a metal material.

The main features are summarized as follows. (1) It has self-lubricating properties and does not require lubrication. (2) The thermal conductivity is good and the temperature does not rise locally. (3) The coefficient of thermal expansion is small. (4) It has excellent heat resistance. (5) Excellent corrosion resistance. (6) Processing is easy, and various shapes can be manufactured.

Therefore, the sliding material is often used in combination with a carbon material, ceramics, cemented carbide or the like. Further, in recent years, hard materials made of a sintered body containing silicon carbide as a main component have come to be used.

This is because the silicon carbide-based sintered body has extremely high hardness, excellent heat resistance and corrosion resistance, and further has high thermal shock resistance which is unusual for ceramics.

On the other hand, on the other hand, since it is an ultra-high hardness material, it can only be processed by cutting with a diamond grindstone, making it difficult to manufacture a sliding material having a complicated shape and having a large friction coefficient. It has the drawback of accelerating the friction of the material.

As a method conceived for facilitating the use of the silicon carbide material having the above-mentioned drawbacks but having the above-mentioned drawbacks as a sliding material having a complicated shape, a sintered body alone ( There is a coating method in which it is used as a coating layer on the surface of another substrate instead of being used as a bulk material.

There are two coating methods, a chemical vapor deposition method and a conversion method. In either method, a carbon material is generally used as a base material.

The chemical vapor deposition method is a method of producing silicon carbide by utilizing thermal decomposition and chemical reaction of a silicon compound and depositing this on the surface of a carbonaceous substrate. Since this method uses a carbon material that is easy to cut as a base material, it is easy to manufacture a sliding material having a complicated shape, and the obtained silicon carbide coating layer is highly pure and dense. When the bond between the base material and the base material is weak and subjected to the action of repeated mechanical or thermal stress,
It has a serious drawback that the coating layer is easily peeled off.

On the other hand, the conversion method is a method in which a silicon monoxide gas generated by the reaction of silicon dioxide with carbon or silicon is directly reacted with carbon on the surface of a carbon substrate to form a coating layer made of silicon carbide. Yes, for example, Japanese Patent Laid-Open No. 1-26496
No. 9 is disclosed. The silicon carbide coating layer obtained by this method has a strong bond with the carbon substrate, but is inferior in terms of denseness.

This is because half of the carbon atoms become carbon monoxide gas and scatter due to the reactions of [Chemical Formula 1] and [Chemical Formula 2], and as a result, the coating layer has a porosity almost equal to that of the carbon substrate. growing. Therefore, in order to use it in a portion where airtightness and impermeability are required, it is necessary to impregnate a thermosetting resin or the like to improve the airtightness of the base material.

[0017]

Embedded image

[0018]

Embedded image

However, the above method requires a very special device, silicon carbide is a difficult-to-process material, it takes time to process, and unnecessary parts are coated. Therefore, the cost is high. Becomes Therefore, there is a method in which a portion of the carbon base material that does not need to be converted to silicon carbide is covered with a special jig or an inert powder and converted.
20584 or JP-A-57-7880. Moreover, a groove is provided on the surface of the carbon base material, and S
Although a method of heat-treating i and converting it to silicon carbide is also proposed in JP-A-61-136961, it has the drawbacks of complicated operations, poor workability, and high cost.

[0020]

Therefore, the present invention solves the above-mentioned problems in conventional sliding materials, is excellent in heat resistance, impermeability and wear resistance, is easy to manufacture, and is low in cost. Moreover, it is intended to provide a new method for producing a carbon-silicon carbide composite material which can be applied to a complicated shape.

In other words, as already mentioned above,
In order to modify the hardness and wear resistance of the carbon base material, the surface of the carbon base material is converted into silicon carbide that is harder and has higher wear resistance, and is modified. It is not always necessary to modify the entire surface of the carbon member to a silicon carbide material, and it is often sufficient to selectively and partially modify only the sliding portion with particularly heavy wear, that is, only a predetermined portion.

Based on the above-mentioned gist, the present invention intends to provide a novel means for selectively reforming and modifying only the surface of a predetermined portion of a carbon base material into a silicon carbide material very easily and efficiently. To do.

[0023]

Means for Solving the Problems As a result of experiments under various conditions, the present inventor processed a carbon base material having an average pore radius of 0.5 μm or more into a product shape, and formed silicon powder only in necessary portions. A resin, especially a resin having a high film-forming property, having no fluidity once cured, and having a low residual carbon rate, for example, a solution of one or more resins selected from polyamide imide, polyvinyl alcohol, polyamide resin, etc. is mixed. To form a slurry, dry it, cure it, and further react the carbon base material with molten silicon at a high temperature of 1500 ° C. or higher to partially convert it into silicon carbide. All the problems can be solved and the present invention has been completed.

[0024]

The function and structure of the present invention will be described in more detail.

(1) The manufacturing method itself may be carried out by using the usual carbon substrate manufacturing method, and the carbon substrate used here includes general graphite materials, isotropic materials and the like. Above all, it is desirable to use a base material having an average pore radius of 0.5 μm or more processed into a product shape. The average pore radius is 0.
When it is less than 5 μm, it becomes difficult for the slurry to penetrate into the pores when the slurry mixed with silicon and resin is applied.

(2) Examples of the resin used include resins having a high film-forming property and a low residual carbon ratio, such as polyamide imide, polyvinyl alcohol, polyamide imide resin, etc., and other aromatic polyimides, aromatic polyamides, Polyphenylenebenzimidazole, polyphenylenebenzobisimidazole, polythiazole, poly p-phenylenevinylene, polyoxadiazole, polybenzothiazole, etc. can also be used. These are used alone or in combination of two or more. Polyamide-imide resin is particularly desirable. As a solvent, it is used after being dissolved in a solvent such as dimethylacetamide, dimethylformamide, dimethylsulfoxide, N-methyl-2pyrrolidone. When a resin with a high residual carbon ratio, such as furfuryl alcohol, or a phenol resin, is used, when high-temperature heat treatment is performed in a later step,
Resin carbide and the reaction product of silicon and silicon may stick to the surface of the carbon substrate and may not be easily removed, which is not desirable.

(3) Silicon powder is mixed and dispersed in this solution to form a slurry.

(4) The slurry is applied to a carbon base material by a suitable means such as spraying or spraying, and applied only to a portion where silicidation is desired.

The solvent part of the slurry partially evaporates and partly penetrates into the base material, and a layer mainly composed of the resin and Si powder finely wrapped around the resin remains on the base material.

(5) After that, dry at about 300 ° C. for 2 hours,
To cure. By this operation, the solvent evaporates and the resin is completely cured.

(6) The material obtained as described in (1) to (5) is subjected to high temperature heat treatment in a non-oxidizing atmosphere such as substitution with an inert gas or in a vacuum of 10 Torr or less.
The heating rate is about 800 ° C / hr, about 1550 to 1600
Hold at 20 ° C for 20 minutes. The heating means is not particularly limited, and any suitable means may be used. This operation causes S
The i component melts and penetrates into the pores of the carbon substrate through the carbonized layer of the resin and reacts with carbon to become SiC.

(7) In the carbon-SiC composite material thus obtained, some carbides of Si and resin remain on the surface layer of the base material,
If it is attached, remove it.

According to the method of the present invention, due to the synergistic effect of the carbon base material (pore radius), Si powder (particle size), selection of resin, etc., very little residue remains on the surface after silicidation of the carbon base material, Moreover, since it is soft, it can be easily removed, and the surface can be precisely processed according to the intended use. This is also one of the major characteristics.

(8) The thickness of the silicified portion of the carbon substrate is usually 0.5 to 3.5 mm, and the thickness of this layer is (resin + S).
i powder) It can be adjusted by increasing or decreasing the coating amount of the mixture.

(9) The result of the surface analysis photograph of the silicified layer obtained by the above method is shown in FIG. This is a method of obtaining the ratio of both of these components from the ratio of the area integrated values of the carbonaceous part (black) and the SiCaceous part (gray), but in the sample prepared by slightly changing the conditions, C The / SiC ratio is in the range of 70/30 to 30/70, and it can be seen that, on average, about 50% of the surface layer portion of the carbon base material has been modified into silicon carbide. However, it goes without saying that the heat-treated portion remains 100% carbonaceous.

[0036]

EXAMPLES The present invention will be described below with reference to examples.

[0037]

Example 1 Bulk density 1.77, average pore radius 1.8 μ
m isotropic graphite material (made by Toyo Tanso Co., Ltd. grade name "Si
C-12 ″) was processed to φ52.5 / φ42.5, while polyamideimide resin (“Al-10”, manufactured by Ohara Kako) was dissolved in N-methyl-2pyrrolidone to give a 20% solution.
Silicon powder (made by Wako Pure Chemical Industries: particle size 30 to 50) was added to this solution.
μ) 60 parts by weight were mixed to form a slurry.

This slurry was applied to the inner peripheral portion of the base material in a thickness of about 3 mm and then cured at 300 ° C. in a dryer.

Further, the temperature was raised to 1600 ° C. in a vacuum furnace, and 30
After holding for a minute, it was cooled and taken out. In the product, Si was melted from the applied portion, penetrated into the base material, reacted with graphite and turned into SiC, and the SiC layer was formed to a depth of 2.5 mm from the surface. The qualitative analysis results of this product are shown below.

1 Qualitative Analysis (Area Analysis) (1) Pretreatment The material was embedded in MMA (methyl methacrylate) and then polished, and then C vapor deposition was performed on the polished surface.

(2) Measurement conditions Acceleration voltage 20 KV Sample current 0.6 nA Measurement time 200 sec Equipment used EMAX-2700 (manufactured by Horiba)

(3) Results FIG. 1 shows a surface analysis photograph of Si.

2 Area Ratio (1) Results Table 1 shows.

[0044]

[Table 1]

[0045]

Example 2 Bulk density 1.70 g / cm ² , average pore radius 1.5
μm isotropic graphite material (manufactured by Toyo Tanso Co., Ltd., “ISEM-
1 "grade name) and the manufacturing method was the same as in Example 1 to form a SiC layer of 2.0 mm. However, the resin used was polyamide (Ohara Kako Co., Ltd.) in a 20% N-methylpyrrolidone solution.

[0046]

Example 3 Bulk density 1.85 g / cm ² , average pore radius 0.8
μm isotropic graphite material (“ISO-5” manufactured by Toyo Tanso Co., Ltd.)
0 ", grade name), a SiC layer was partially formed by 1.0 mm.

However, the resin used was a 20% aqueous solution of polyvinyl alcohol.

[0048]

Example 4 Bulk density 1.86 g / cm ² , average pore radius 0.2
5 μm isotropic graphite material (“ISO-8” manufactured by Toyo Tanso Co., Ltd.)
6 "grade name) and similarly, the SiC layer is 0.2 mm
Formed.

However, the resin used was a 20% solution of the polyamide-imide resin as in Example 1.

[0050]

[Comparative Example 1] Bulk density 1.90 g / cm ² , average pore radius 0.2
μm isotropic graphite material (“ISO-8” manufactured by Toyo Tanso Co., Ltd.)
8 ”grade name) was used for silicidation by the same manufacturing method as in Example 1. No silicon silicon carbon layer was observed.

[0051]

[Comparative Example 2] Bulk density 1.70 g / cm ² , average pore radius 1.5
μm isotropic graphite material (Toyo Tanso Co., Ltd. “ISEM-1”)
A liquid phenol resin (“PQ-50273” manufactured by Sumitomo Durez Co., Ltd.) and silicon powder were mixed using a grade name) to form a slurry, which was applied and then silicified by the production method of Comparative Example 1 described above. After the treatment, a hard adhered substance (silicon-glassy carbide) adhered to the coated part, and it was difficult to remove it. Further, cracks were generated in the surface layer of the silicidation portion, and a good silicon carbide layer was not formed. Example 1
Table 2 shows the physical properties of the composite materials of No. 4 and Comparative Examples 1 and 2.

[0052]

[Table 2]

[0053]

EFFECTS OF THE INVENTION A simple and economical new method for selectively silicifying only the surface of a specific portion of a carbon material has been found.

The material obtained by this method is suitable as a sliding member.

[0055]

[Brief description of drawings]

[0056]

[Figure 1]

Surface analysis photograph

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 13, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

FIG. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 25, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

(9) The result of the surface analysis photograph of the silicified layer obtained by the above method is shown in FIG. This is a method of obtaining the ratio of both of these components from the ratio of the area integrated values of the carbonaceous part ( shaded part ) and the SiC part ( white part ), but the sample prepared by slightly changing the conditions Then C
/ SiC ratio is in the range of 70/30 to 30/70,
It can be seen that, on average, about 50% of the surface layer portion of the carbon base material has been modified into silicon carbide. However, the heat treated part is carbonaceous 1
Needless to say, it remains 00%.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

FIG. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 23, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Detailed explanation of the invention

[Correction method] Change

[Correction content]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing a composite material in which only a predetermined portion of the surface of a carbon substrate has been transformed and converted into a composite material in which carbon and silicon carbide are mixed.

Such a carbon-SiC composite material is used for sliding members such as bearings, shaft shafts, which are required to have wear resistance.
It is applied to the inner wall of piston cylinders, piston rings, thrust plates, valve sliding parts, vanes, etc.

[0003]

2. Description of the Related Art The main uses of carbon products for machinery are:
The bearings are roughly classified into bearings, piston rings, seals, vanes, etc., all of which are used in a state of manual contact with a mating material. Therefore, slidability including lubricity is a very important factor for these purposes. In the case of a metal material, a lubricating oil is usually used in order to prevent obstacles such as heat generation, seizure, and power loss due to manual friction.

However, when the lubricating oil is heated to a high temperature, it flows out, evaporates and decomposes, loses fluidity at a low temperature and solidifies, and when it is used in a liquid, it is dispersed and dissolved in the liquid. It often loses its function.

Further, depending on the application, there are cases where the oil content is disliked from being mixed into the liquid, or there is a case where the oil supply is impossible due to the mechanical structure.

Since the carbon material has a weak binding force in the C-axis direction due to its structure, it has a self-lubricating property due to the sliding of the hexagonal mesh surface of the crystal, and the normal lubricating property as described above cannot be used, or oil supply is difficult. In this case, it is particularly suitable.

Further, the carbon material is excellent in corrosion resistance and heat resistance in addition to self-lubricating property, and almost satisfies the requirements as a mechanical material except that it is not as strong as a metal material.

The main features are summarized as follows. (1) It has self-lubricating properties and does not require lubrication. (2) The thermal conductivity is good and the temperature does not rise locally. (3) The coefficient of thermal expansion is small. (4) It has excellent heat resistance. (5) Excellent corrosion resistance. (6) Processing is easy, and various shapes can be manufactured.

Therefore, the sliding material is often used in combination with a carbon material, ceramics, cemented carbide or the like. Further, in recent years, hard materials made of a sintered body containing silicon carbide as a main component have come to be used.

This is because the silicon carbide-based sintered body has extremely high hardness, excellent heat resistance and corrosion resistance, and further has high thermal shock resistance which is unusual for ceramics.

On the other hand, on the other hand, since it is an ultra-high hardness material, it can only be processed by cutting with a diamond grindstone, making it difficult to manufacture a sliding material having a complicated shape and having a large friction coefficient. It has the drawback of accelerating the friction of the material.

As a method conceived for facilitating the use of the silicon carbide material having the above-mentioned drawbacks but having the above-mentioned drawbacks as a sliding material having a complicated shape, a sintered body alone ( There is a coating method in which it is used as a coating layer on the surface of another substrate instead of being used as a bulk material.

There are two coating methods, a chemical vapor deposition method and a conversion method. In either method, a carbon material is generally used as a base material.

The chemical vapor deposition method is a method of producing silicon carbide by utilizing thermal decomposition and chemical reaction of a silicon compound and depositing this on the surface of a carbonaceous substrate. Since this method uses a carbon material that is easy to cut as a base material, it is easy to manufacture a sliding material having a complicated shape, and the obtained silicon carbide coating layer is highly pure and dense. When the bond between the base material and the base material is weak and subjected to the action of repeated mechanical or thermal stress,
It has a serious drawback that the coating layer is easily peeled off.

On the other hand, the conversion method is a method in which a silicon monoxide gas generated by the reaction of silicon dioxide with carbon or silicon is directly reacted with carbon on the surface of a carbon substrate to form a coating layer made of silicon carbide. Yes, for example, Japanese Patent Laid-Open No. 1-26496
No. 9 is disclosed. The silicon carbide coating layer obtained by this method has a strong bond with the carbon substrate, but is inferior in terms of denseness.

This is because half of the carbon atoms become carbon monoxide gas and scatter due to the reactions of [Chemical Formula 1] and [Chemical Formula 2], and as a result, the coating layer has a porosity almost equal to that of the carbon substrate. growing. Therefore, in order to use it in a portion where airtightness and impermeability are required, it is necessary to impregnate a thermosetting resin or the like to improve the airtightness of the base material.

[0017]

Embedded image

[0018]

Embedded image

However, the above method requires a very special device, silicon carbide is a difficult-to-process material, it takes time to process, and unnecessary parts are coated. Therefore, the cost is high. Becomes Therefore, there is a method in which a portion of the carbon base material that does not need to be converted to silicon carbide is covered with a special jig or an inert powder and converted.
20584 or JP-A-57-7880. Moreover, a groove is provided on the surface of the carbon base material, and S
Although a method of heat-treating i and converting it to silicon carbide is also proposed in JP-A-61-136961, it has the drawbacks of complicated operations, poor workability, and high cost.

[0020]

Therefore, the present invention solves the above-mentioned problems in conventional sliding materials, is excellent in heat resistance, impermeability and wear resistance, is easy to manufacture, and is low in cost. Moreover, it is intended to provide a new method for producing a carbon-silicon carbide composite material which can be applied to a complicated shape.

In other words, as already mentioned above,
In order to modify the hardness and wear resistance of the carbon base material, the surface of the carbon base material is converted into silicon carbide that is harder and has higher wear resistance, and is modified. It is not always necessary to modify the entire surface of the carbon member to a silicon carbide material, and it is often sufficient to selectively and partially modify only the sliding portion with particularly heavy wear, that is, only a predetermined portion.

Based on the above-mentioned gist, the present invention intends to provide a novel means for selectively reforming and modifying only the surface of a predetermined portion of a carbon base material into a silicon carbide material very easily and efficiently. To do.

[0023]

Means for Solving the Problems As a result of experiments under various conditions, the present inventor processed a carbon base material having an average pore radius of 0.5 μm or more into a product shape, and formed silicon powder only in necessary portions. A resin, especially a resin having a high film-forming property, having no fluidity once cured, and having a low residual carbon rate, for example, a solution of one or more resins selected from polyamide imide, polyvinyl alcohol, polyamide resin, etc. is mixed. To form a slurry, dry it, cure it, and further react the carbon base material with molten silicon at a high temperature of 1500 ° C. or higher to partially convert it into silicon carbide. All the problems can be solved and the present invention has been completed.

[0024]

The function and structure of the present invention will be described in more detail.

(1) The manufacturing method itself may be carried out by using the usual carbon substrate manufacturing method, and the carbon substrate used here includes general graphite materials, isotropic materials and the like. Above all, it is desirable to use a base material having an average pore radius of 0.5 μm or more processed into a product shape. The average pore radius is 0.
When it is less than 5 μm, it becomes difficult for the slurry to penetrate into the pores when the slurry mixed with silicon and resin is applied.

(2) Examples of the resin used include resins having a high film-forming property and a low residual carbon ratio, such as polyamide imide, polyvinyl alcohol, polyamide imide resin, etc., and other aromatic polyimides, aromatic polyamides, Polyphenylenebenzimidazole, polyphenylenebenzobisimidazole, polythiazole, poly p-phenylenevinylene, polyoxadiazole, polybenzothiazole, etc. can also be used. These are used alone or in combination of two or more. Polyamide-imide resin is particularly desirable. As a solvent, it is used after being dissolved in a solvent such as dimethylacetamide, dimethylformamide, dimethylsulfoxide, N-methyl-2pyrrolidone. When a resin with a high residual carbon ratio, such as furfuryl alcohol, or a phenol resin, is used, when high-temperature heat treatment is performed in a later step,
Resin carbide and the reaction product of silicon and silicon may stick to the surface of the carbon substrate and may not be easily removed, which is not desirable.

(3) Silicon powder is mixed and dispersed in this solution to form a slurry.

(4) The slurry is applied to a carbon base material by a suitable means such as spraying or spraying, and applied only to a portion where silicidation is desired.

The solvent part of the slurry partially evaporates and partly penetrates into the base material, and a layer mainly composed of the resin and Si powder finely wrapped around the resin remains on the base material.

(5) After that, dry at about 300 ° C. for 2 hours,
To cure. By this operation, the solvent evaporates and the resin is completely cured.

(6) The material obtained as described in (1) to (5) is subjected to high temperature heat treatment in a non-oxidizing atmosphere such as substitution with an inert gas or in a vacuum of 10 Torr or less.
The heating rate is about 800 ° C / hr, about 1550 to 1600
Hold at 20 ° C for 20 minutes. The heating means is not particularly limited, and any suitable means may be used. This operation causes S
The i component melts and penetrates into the pores of the carbon substrate through the carbonized layer of the resin and reacts with carbon to become SiC.

(7) In the carbon-SiC composite material thus obtained, some carbides of Si and resin remain on the surface layer of the base material,
If it is attached, remove it.

According to the method of the present invention, due to the synergistic effect of the carbon base material (pore radius), Si powder (particle size), selection of resin, etc., very little residue remains on the surface after silicidation of the carbon base material, Moreover, since it is soft, it can be easily removed, and the surface can be precisely processed according to the intended use. This is also one of the major characteristics.

(8) The thickness of the silicified portion of the carbon substrate is usually 0.5 to 3.5 mm, and the thickness of this layer can be adjusted by increasing or decreasing the coating amount of the (resin + Si powder) mixture.

(9) The result of the surface analysis photograph of the silicified layer obtained by the above method is shown in FIG. This is a method of obtaining the ratio of both of these components from the ratio of the area integrated values of the carbonaceous part ( shaded part ) and the SiC part ( white part ), but the sample prepared by slightly changing the conditions Then C
/ SiC ratio is in the range of 70/30 to 30/70,
It can be seen that, on average, about 50% of the surface layer portion of the carbon base material has been modified into silicon carbide. However, the heat treated part is carbonaceous 1
Needless to say, it remains 00%.

[0036]

EXAMPLES The present invention will be described below with reference to examples.

[0037]

Example 1 Bulk density is 1.77 and average pore radius is 1.8.
A μm isotropic graphite material (grade name “SiC-12” manufactured by Toyo Tanso Co., Ltd.) was processed into φ52.5 / φ42.5, while polyamideimide resin (“Al-10”, manufactured by Ohara Kako) was used. It was dissolved in N-methyl-2pyrrolidone to give a 20% solution. 60 parts by weight of silicon powder (manufactured by Wako Pure Chemical Industries: particle size 30 to 50 μ) was mixed with this solution to form a slurry.

About 3 mm of this slurry was applied to the inner peripheral portion of the base material.
After being applied in a thickness, it was cured in a dryer at 300 ° C.

Further, the temperature was raised to 1600 ° C. in a vacuum furnace, and 30
After holding for a minute, it was cooled and taken out. In the product, Si melted from the coated part, penetrated into the base material, reacted with graphite, and turned into SiC, and a SiC layer was formed to a depth of 2.5 mm from the surface. The qualitative analysis results of this product are shown below.

1 Qualitative Analysis (Area Analysis) (1) Pretreatment The material was embedded in MMA (methyl methacrylate) and then polished, and then C vapor deposition was performed on the polished surface.

(2) Measurement conditions Acceleration voltage 20KV Sample current 0.6nA Measurement time 200sec Equipment used EMAX-2700 (manufactured by Horiba)

(3) Results FIG. 1 shows a surface analysis photograph of Si.

2 Area Ratio (1) Results Table 1 shows.

[0044]

[Table 1]

[0045]

Example 2 An isotropic graphite material having a bulk density of 1.70 g / cm ² and an average pore radius of 1.5 μm (manufactured by Toyo Tanso Co., Ltd., “I”)
SEM-1 "grade name) was used, and the following manufacturing method was performed in the same manner as in Example 1 to form a SiC layer of 2.0 mm.
However, the resin used is polyamide (Ohara Kako Co., Ltd.)
-Methylpyrrolidone used as a 20% solution.

[0046]

Example 3 An isotropic graphite material having a bulk density of 1.85 g / cm ² and an average pore radius of 0.8 μm (“IS” manufactured by Toyo Tanso Co., Ltd.)
O-50 ", grade name) was partially formed with a SiC layer of 1.0 mm.

However, the resin used was a 20% aqueous solution of polyvinyl alcohol.

[0048]

Example 4 An isotropic graphite material having a bulk density of 1.86 g / cm ² and an average pore radius of 0.25 μm (“I” manufactured by Toyo Tanso Co., Ltd.)
A SiC layer of 0.2 mm was similarly formed using "SO-86" grade name).

However, the resin used was a 20% solution of the polyamide-imide resin as in Example 1.

[0050]

Comparative Example 1 An isotropic graphite material having a bulk density of 1.90 g / cm ² and an average pore radius of 0.2 μm (“IS” manufactured by Toyo Tanso Co., Ltd.)
O-88 "grade name) was used for silicidation by the same manufacturing method as in Example 1. No silicon silicon carbon layer was observed.

[0051]

[Comparative Example 2] An isotropic graphite material having a bulk density of 1.70 g / cm ² and an average pore radius of 1.5 μm (“ISE” manufactured by Toyo Tanso Co., Ltd.)
M-1 "grade name), liquid phenolic resin (" PQ-50273 "manufactured by Sumitomo Durez Co., Ltd.) and silicon powder were mixed to form a slurry, which was applied and then silicified by the production method of Comparative Example 1 described above. . After the treatment, a hard adhered substance (silicon-glassy carbide) adhered to the coated part, and it was difficult to remove it. Further, cracks were generated in the surface layer of the silicidation portion, and a good silicon carbide layer was not formed. Table 2 shows the physical properties of the composite materials of Examples 1 to 4 and Comparative Examples 1 and 2.

[0052]

[Table 2]

[0053]

EFFECTS OF THE INVENTION A simple and economical new method for selectively silicifying only the surface of a specific portion of a carbon material has been found.

The material obtained by this method is suitable as a sliding member.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

[Figure 1] Surface analysis diagram

Claims (2)

[Claims] 1. A slurry obtained by mixing and suspending metal Si powder in a resin or a solvent solution thereof is applied to only a predetermined portion of a material obtained by processing a carbon base material having an average pore radius of 0.5 μm or more into a product shape. A method for producing a carbon-silicon carbide composite material, which comprises drying, curing, and calcining at 1500 ° C. or higher. 2. The method for producing a composite material according to claim 1, wherein the resin is at least one of polyimide amide, polyvinyl alcohol, and polyamide resin.