JP2016113345A - Graphite-silicon carbide composite and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a graphite-silicon carbide composite excellent in high-temperature oxidation resistance and little in variation of quality, and a method of easily producing the same.SOLUTION: The graphite-silicon carbide composite is provided which includes: a graphite base material; and a silicon carbide layer formed on the surface of the graphite base material, and in which the silicon carbide layer contains Fe, and the content of Fe is 5-5,000 ppm. The method of producing the graphite-silicon carbide composite is also provided which comprises : a step (1) of preparing a metallic silicon powder having an Fe content of 8-8,000; a step (2) of melt-spraying the metallic silicon powder on the surface of the graphite base material; and a step (3) of subjecting the graphite base material melt-sprayed with the metallic silicon powder to heat treatment in a non-oxidation atmosphere at the temperature range of 1,100-1,700°C to form a silicon carbide layer on the surface of the graphite base material.SELECTED DRAWING: None

Description

  The present invention relates to a graphite-silicon carbide composite and a method for producing the same, and in particular, a graphite-silicon carbide composite that is suitably used for high-temperature structural materials, jigs, semiconductor device members, liquid crystal device members, mechanical sliding materials, and the like. The present invention relates to a body and a manufacturing method thereof.

  A graphite material is a material excellent in high temperature characteristics, mechanical strength, and workability, and is used as various high temperature materials (materials used at high temperatures). However, graphite materials are limited to use in a non-oxidizing atmosphere due to poor oxidation resistance, and oxide ceramics such as silicon carbide, silicon nitride, and alumina have been used as high-temperature materials used in an oxidizing atmosphere. It was. However, these ceramics have other problems such as inferior processability, difficulty in increasing the size, and inferior thermal shock resistance.

  Therefore, in order to improve the oxidation resistance, it has been attempted to produce a graphite-silicon carbide composite in which the surface of the graphite material is covered with a silicon carbide layer.

Conventionally, several methods have been proposed as a method for producing a graphite-silicon carbide composite. For example, in Patent Document 1, a carbon-based material having a specific pore size occupied by fine pores of 0.02 cm ³ / g or more is used, and a graphite-silicon carbide composite is manufactured by a conversion method using SiO gas. In Patent Document 2, a porous silicon carbide sintered body having an open porosity of 5 to 55% and an average pore diameter of 0.1 to 100 μm is prepared, and carbon is filled in the open pores to form graphite. A method for producing a silicon carbide composite, Patent Document 3 discloses a method for producing a graphite-silicon carbide composite by infiltrating and reacting molten silicon with a porous graphite base material, and Patent Document 4 discloses a carbon base material. A method of forming a SiC coating film by CVD method after coating a Si film by CVD method and heat-treating at 1300 ° C. or higher, and further forming a SiC coating film by CVD method. Dioxide at ℃ A method is described in which a silicon carbide film is formed by chemical vapor deposition after reacting with silicon to siliconize the surface portion to form a silicon carbide base.

Japanese Patent Publication No. 61-11911 Japanese Patent Laid-Open No. 62-132787 Japanese Patent No. 2620294 JP 2002-128580 A Japanese Patent Laid-Open No. 63-225591

  Each of the conventional methods of Patent Documents 1 to 5 described above is a method that undergoes a complicated manufacturing process, and the manufacturing yield is poor, resulting in an expensive graphite-silicon carbide composite, or variations in the silicon carbide layer. However, the method has a problem that the product has a large quality variation and cannot be said to be an excellent method for industrial production.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a graphite-silicon carbide composite that is excellent in high-temperature oxidation resistance and has little variation in quality. Moreover, an object of this invention is to provide the method which can manufacture such a graphite carbon composite easily.

  In order to solve the above problems, in the present invention, a graphite-silicon carbide composite having a graphite base material and a silicon carbide layer formed on the surface of the graphite base material, wherein the silicon carbide layer contains Fe. And a graphite-silicon carbide composite having a Fe content in the silicon carbide layer of 5 to 5000 ppm.

  In the graphite-silicon carbide composite of the present invention, the adhesion between the graphite substrate and the silicon carbide layer is achieved by the content of Fe contained in the silicon carbide layer formed on the surface of the graphite substrate being within the above range. Can be improved. With such a graphite-silicon carbide composite, peeling of the silicon carbide layer from the graphite substrate can be suppressed, and a graphite-silicon carbide composite excellent in high-temperature oxidation resistance can be obtained. As a result, such a graphite-silicon carbide composite can be suitably used as a heat resistant material.

  At this time, it is preferable that the thickness of the silicon carbide layer is 10 to 300 μm.

  If the thickness of the silicon carbide layer is within such a range, it is possible to provide sufficient gas impermeability, and it becomes a graphite-silicon carbide composite that can withstand long-term use in a high-temperature oxidizing atmosphere.

  Moreover, it is preferable that the said silicon carbide layer contains Al and Ca further, Al content rate in the said silicon carbide layer is 10-1000 ppm, and Ca content rate is 5-1000 ppm.

  If the content rate of Al and Ca contained in the said silicon carbide layer is in such a range, the adhesiveness of a graphite base material and a silicon carbide layer can further be improved.

Further, in the present invention, a method for producing a graphite-silicon carbide composite,
(1) preparing a metal silicon powder having an Fe content of 8 to 8000 ppm;
(2) spraying the metal silicon powder on the surface of the graphite substrate;
(3) heat treating the graphite substrate sprayed with the metal silicon powder in a temperature range of 1100 to 1700 ° C. in a non-oxidizing atmosphere to form a silicon carbide layer on the surface of the graphite substrate. A method for producing a graphite-silicon carbide composite is provided.

  With such a method for producing a graphite-silicon carbide composite, a graphite-silicon carbide composite having excellent high-temperature oxidation resistance and little variation in quality can be produced by a simple method.

  At this time, it is preferable that the average particle diameter of the said metal silicon powder is 0.5-50 micrometers.

  If the average particle diameter of the said metal silicon powder is 0.5 micrometer or more, thermal spraying will become easy and uniform thermal spraying can be achieved. Moreover, if the said average particle diameter is 50 micrometers or less, the conversion of the silicon carbide layer by heat processing can be performed easily enough.

  Moreover, in the step of preparing the metal silicon powder, it is preferable to prepare a metal silicon powder further containing Al and Ca, having an Al content of 16 to 1600 ppm and a Ca content of 8 to 1600 ppm.

  By using such a metal silicon powder, it is possible to obtain a graphite-silicon carbide composite having further excellent high-temperature oxidation resistance.

  As described above, with the graphite-silicon carbide composite of the present invention, the adhesion between the graphite base material and the silicon carbide layer is improved, and peeling of the silicon carbide layer is suppressed, resulting in high temperature oxidation resistance. It becomes an excellent graphite-silicon carbide composite. Therefore, the graphite-silicon carbide composite of the present invention can be used for various applications as a heat-resistant material. Further, the method for producing a graphite-silicon carbide composite of the present invention is simple, excellent in high-temperature oxidation resistance, suitable for use as a heat-resistant material, and easily producing a graphite-silicon carbide composite with little quality variation. It can be obtained and can sufficiently withstand industrial scale production.

  As described above, there has been a demand for the development of a graphite-silicon carbide composite that is excellent in high-temperature oxidation resistance and has little quality variation, and a method for producing the same.

  As a result of intensive studies to solve the above problems, the present inventors have determined that the Fe content contained in the silicon carbide layer formed on the surface of the graphite substrate is within a predetermined range, It has been found that the adhesion with the silicon carbide layer is improved and the high-temperature oxidation resistance of the graphite-silicon carbide composite is improved. In addition, as a method for producing the above graphite-silicon carbide composite, the present inventors easily sprayed a metal silicon powder having an Fe content within a predetermined range on a graphite substrate, and then heat-treated it. It becomes possible to form a silicon carbide layer having a certain thickness with little variation on the surface of the graphite substrate, and it is possible to produce a graphite-silicon carbide composite that can sufficiently withstand use in a high-temperature oxidizing atmosphere. As a result, the present invention has been completed.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[Graphite-carbon silicon composite]
The graphite-carbon silicon composite of the present invention has a graphite base material and a silicon carbide layer formed on the surface of the graphite base material. The silicon carbide layer contains Fe, and the Fe content is predetermined. Within the range. Specifically, the Fe content contained in the silicon carbide layer is 5 to 5000 ppm, preferably 50 to 3000 ppm. Such a graphite-carbon silicon composite can improve high-temperature oxidation resistance. If the Fe content is less than 5 ppm, the adhesion between the graphite base material and the silicon carbide layer may be reduced, and the silicon carbide layer may be peeled off, resulting in reduced high-temperature oxidation resistance. On the other hand, when the Fe content exceeds 5000 ppm, the silicon carbide layer contains an Fe—Si alloy having a low melting point, and the high-temperature oxidation resistance is lowered.

  Moreover, at this time, it is preferable that the said silicon carbide layer further contains Al and Ca, and Al content rate in this silicon carbide layer is 10-1000 ppm, and Ca content rate is 5-1000 ppm.

  The Al content contained in the silicon carbide layer of the graphite-silicon carbide composite of the present invention is preferably 10 to 1000 ppm as described above, and more preferably 50 to 800 ppm. If Al content rate is 10 ppm or more, the adhesiveness of a graphite base material and a silicon carbide layer can be strengthened, and peeling of a silicon carbide layer can be suppressed. Therefore, the high temperature oxidation resistance of the graphite-silicon carbide composite can be increased. In addition, when the Al content is 1000 ppm or less, the silicon carbide layer is unlikely to contain an Al—Si alloy having a low melting point, so that high-temperature oxidation resistance can be increased.

  The Ca content contained in the silicon carbide layer of the graphite-silicon carbide composite of the present invention is preferably 5 to 1000 ppm, more preferably 50 to 800 ppm as described above. If Ca content rate is 5 ppm or more, the adhesiveness of a graphite base material and a silicon carbide layer can be strengthened, and peeling of a silicon carbide layer can be suppressed. Therefore, the high temperature oxidation resistance of the graphite-silicon carbide composite can be increased. Moreover, if Ca content is 1000 ppm or less, since a Ca-Si alloy with low melting | fusing point is hard to be contained in a silicon carbide layer, high temperature oxidation resistance can be made high.

  Here, the content rate of the said metal (Fe, Al, Ca) can be measured with the following measuring method. That is, when 50% by mass hydrofluoric acid is added to the sample and the reaction starts, 50% by mass nitric acid is further added, and the treatment liquid completely melted by heating to 200 ° C. is subjected to ICP-AES (inductively coupled plasma-emission spectroscopy) ( Analyze and measure with Agilent 730C).

  The Fe, Al, and Ca contents in the silicon carbide layer include Fe, Al, and Ca in the metal silicon powder used in the method for producing a graphite-silicon carbide composite of the present invention, as will be described in detail later. Value related to rate.

  The thickness of the silicon carbide layer of the graphite-silicon carbide composite of the present invention is not particularly limited, but is preferably 10 μm to 300 μm, particularly preferably 10 μm to 200 μm. If the thickness of the silicon carbide layer is 10 μm or more, a graphite-silicon carbide composite that can more reliably have sufficient gas impermeability and can withstand long-term use in a high-temperature oxidizing atmosphere; can do. Further, when the thickness is 300 μm or less, the gas impermeability is sufficiently good, and the production cost of the silicon carbide layer can be suppressed.

  Here, the thickness of the silicon carbide layer corresponds to the thickness of the metal silicon powder (the thickness of the metal silicon powder layer) sprayed when the graphite-silicon carbide composite is produced. It can be controlled by the thickness.

[Method for producing graphite-silicon carbide composite]
Next, the manufacturing method of the graphite-silicon carbide composite of this invention is demonstrated. The graphite-silicon carbide composite of the present invention is easily obtained by thermally spraying a metallic silicon powder having a Fe content in the range of 8 to 8000 ppm on a graphite substrate and further performing a heat treatment in a non-oxidizing atmosphere. be able to. Hereinafter, the manufacturing method will be described in more detail.

  First, a metal silicon powder having an Fe content of 8 to 8000 ppm is prepared (step (1)). Next, this metal silicon powder is sprayed onto the surface of the graphite substrate (step (2)). The thermal spraying method is not particularly limited, and a plasma spraying method, a gas spraying method using acetylene, propane, kerosene or the like as a fuel gas, a high-speed gas spraying method, or the like is appropriately used. Specifically, metal silicon powder is supplied into a plasma flame or a gas flame, and is made into a semi-molten state and sprayed onto a graphite substrate. In particular, it is preferable to use a plasma spraying method for the reason that a film can be formed with higher adhesion at a higher temperature.

  The graphite substrate used in the present invention is not particularly limited, and CIP (cold isostatic pressing) molded products, extruded molded products, C / C composites, etc. may be used depending on the application. In particular, C / C composites have high strength and are more preferably used. The C / C composite is also called a carbon fiber reinforced carbon composite material, and is a material made of carbon fiber and a carbonaceous base material (filler).

  Also, as the metal silicon powder to be sprayed, semiconductor grade, ceramic grade, chemical grade powder, etc. can be used depending on the purpose, but what is important in the present invention is the Fe content of the metal silicon powder to be sprayed. Is 8 to 8000 ppm. The Fe content of the metal silicon powder sprayed in the present invention is preferably 80 to 4800 ppm. When the Fe content of the metal silicon powder is less than 8 ppm, the reactivity between the graphite base material and the metal silicon powder is reduced, and the conversion rate of the silicon carbide layer formed on the surface of the graphite base material is reduced. The layer cannot be formed, and the high-temperature oxidation resistance decreases. Conversely, if the Fe content of the metal silicon powder is greater than 8000 ppm, an Fe—Si alloy having a low melting point is produced, and high-temperature oxidation resistance decreases.

  Next, the graphite substrate sprayed with the metal silicon powder is heat-treated to form a silicon carbide layer on the surface of the graphite substrate (step (3)). At this time, the heat treatment temperature is 1100 ° C to 1700 ° C, preferably 1200 ° C to 1500 ° C. When the heat treatment temperature is lower than 1100 ° C., the silicon carbide conversion rate of the metal silicon powder becomes small, and the silicon carbide layer formed on the surface of the graphite substrate contains a large amount of unreacted metal silicon powder. On the other hand, when the temperature exceeds 1700 ° C., the temperature is far higher than the melting point of the metal silicon powder, so that the sprayed metal silicon powder melts and the film thickness variation of the silicon carbide layer increases.

  The atmosphere for the heat treatment is not particularly limited as long as it is a non-oxidizing atmosphere. For example, it can be performed in an inert gas such as Ar or He under normal pressure or reduced pressure. Further, the apparatus for performing the heat treatment is not particularly limited, and a batch furnace, a continuous tunnel furnace, or the like can be used. The heat treatment time is not particularly limited, and the heat treatment may be performed only for a time during which the metal silicon powder layer formed by thermal spraying is sufficiently converted into silicon carbide. Although the heat treatment time depends on conditions such as the particle size of the silicon carbide powder, the thermal spraying method, the heat treatment temperature, etc., it can be, for example, 30 minutes to 24 hours.

  The Fe content in the metal silicon powder used in the production method of the present invention is related to the Fe content in the silicon carbide layer of the graphite-silicon carbide composite of the present invention. Specifically, the Fe content in the silicon carbide layer of the graphite-silicon carbide composite obtained by the production method of the present invention is approximately 50 to 70% with respect to the Fe content in the thermally sprayed metal silicon powder. It becomes the value of. That is, if the Fe content in the metal silicon powder is in the range of 8 to 8000 ppm, the Fe content in the silicon carbide layer of the produced graphite-silicon carbide composite is in the range of about 5 to 5000 ppm. .

  In the step of preparing the metal silicon powder (step (1)), the metal silicon powder may further include Al and Ca, and the content of Al and Ca may be within a predetermined range. preferable.

  Specifically, the metal silicon powder sprayed in the present invention preferably has an Al content of 16 to 1600 ppm, and more preferably 80 to 1280 ppm. If the Al content of the metal silicon powder is 16 ppm or more, the reactivity between the graphite base material and the metal silicon powder can be increased, and the conversion rate of the silicon carbide layer formed on the surface of the graphite base material can be increased. And a uniform silicon carbide layer can be stably formed. As a result, it is possible to obtain a graphite-silicon carbide composite having further excellent high-temperature oxidation resistance. Further, when the Al content of the metal silicon powder is 1600 ppm or less, an Al—Si alloy having a low melting point is difficult to be generated, so that high-temperature oxidation resistance can be increased.

  The metal silicon powder sprayed in the present invention preferably has a Ca content of 8 to 1600 ppm, and more preferably 80 to 1280 ppm. If the Ca content of the metal silicon powder is 8 ppm or more, the reactivity between the graphite base material and the metal silicon powder can be increased, and the conversion rate of the silicon carbide layer formed on the surface of the graphite base material can be increased. And a uniform silicon carbide layer can be stably formed. As a result, it is possible to obtain a graphite-silicon carbide composite having further excellent high-temperature oxidation resistance. Further, if the Ca content of the metal silicon powder is 1600 ppm or less, a Ca—Si alloy having a low melting point is unlikely to be produced, so that high temperature oxidation resistance can be enhanced.

  Here, the content of Al and Ca in the metal silicon powder used in the production method of the present invention is the same as the content of Fe, but the content of Al and Ca in the silicon carbide layer of the graphite-silicon carbide composite of the present invention. Related to rate. That is, if the Al content in the metal silicon powder is in the range of 16 to 1600 ppm, the Al content in the silicon carbide layer of the resulting graphite-silicon carbide composite is in the range of about 10 to 1000 ppm. If the Ca content in the metal silicon powder is in the range of 8 to 1600 ppm, the Al content in the silicon carbide layer of the resulting graphite-silicon carbide composite is in the range of about 5 to 1000 ppm.

  In addition, the content rate of Fe, Al, and Ca in the said metal silicon powder can be measured by the method similar to the method mentioned above.

The particle diameter of the metal silicon powder is not particularly limited, but it is desirable that the average particle diameter is 0.5 to 50 μm, particularly 3 to 30 μm. When the average particle diameter is 0.5 μm or more, the thermal spraying of the metal silicon powder becomes easy, and uniform thermal spraying can be achieved. Further, if the average particle size is 50 μm or less, silicon carbide conversion by heat treatment can be performed easily and sufficiently, and as a result, the silicon carbide layer formed on the surface of the graphite substrate has a small amount of unreacted metal silicon powder. Can be. Here, the average particle diameter is a value measured as a mass average value D ₅₀ (that is, a particle diameter or a median diameter when the cumulative mass is 50%) in particle size distribution measurement by a laser light diffraction method.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example and a comparative example, this invention is not limited to these.

[Example 1]
A metal silicon powder layer having a Fe content of 500 ppm, an Al content of 300 ppm, a Ca content of 150 ppm, and an average particle size of 20 μm is applied to the entire surface of a CIP-molded graphite substrate having dimensions of 50 mm × 50 mm × thickness 3 mm. The film was sprayed by plasma spraying so that the thickness of the film became 40 μm. Next, this sprayed material was charged into a batch furnace and heat-treated in an Ar atmosphere at a temperature of 1450 ° C. for 3 hours.

  When the cross-sectional observation of the obtained base material and the X-ray diffraction analysis of the surface layer were performed, it was a graphite-silicon carbide composite in which a green silicon carbide layer was formed on the surface of the graphite base material.

  Next, in order to evaluate the high-temperature oxidation resistance of the obtained graphite-silicon carbide composite, the graphite-silicon carbide composite was kept in the atmosphere at 1000 ° C. for 1 hour. When the weight loss was measured after cooling, the weight loss was 0%, and it was confirmed that the material was excellent in high-temperature oxidation resistance. Moreover, when Fe, Al, and Ca content rate contained in a silicon carbide layer were measured, Fe content rate was 320 ppm, Al content rate was 200 ppm, and Ca content rate was 95 ppm.

[Example 2]
A graphite-silicon carbide composite was produced in the same manner as in Example 1 except that a metal silicon powder having an Fe content of 20 ppm, an Al content of 20 ppm, and a Ca content of 10 ppm was used as the thermal spray material.

  When the cross section of the obtained base material was observed and the surface layer was subjected to X-ray diffraction analysis, it was observed that a green silicon carbide layer was formed on the surface of the graphite base material as in Example 1.

  Next, in order to evaluate the oxidation resistance of the obtained graphite-silicon carbide composite, high temperature oxidation resistance was evaluated in the same manner as in Example 1. As a result, the weight loss was 3.1%, and it was confirmed that the material was excellent in high-temperature oxidation resistance. Moreover, when Fe, Al, and Ca content rate contained in a silicon carbide layer were measured, Fe content rate was 13 ppm, Al content rate was 12 ppm, and Ca content rate was 6 ppm.

Example 3
A graphite-silicon carbide composite was produced in the same manner as in Example 1 except that metal silicon powder having an Fe content of 4800 ppm, an Al content of 900 ppm, and a Ca content of 800 ppm was used as the thermal spray material.

  When the cross section of the obtained base material was observed and the surface layer was subjected to X-ray diffraction analysis, it was observed that a green silicon carbide layer was formed on the surface of the graphite base material as in Example 1.

  Next, in order to evaluate the oxidation resistance of the obtained graphite-silicon carbide composite, high temperature oxidation resistance was evaluated in the same manner as in Example 1. As a result, the weight loss was 2.7%, and it was confirmed that the material was excellent in high-temperature oxidation resistance. Moreover, when Fe, Al, and Ca content rate contained in a silicon carbide layer were measured, Fe content rate was 3100 ppm, Al content rate was 580 ppm, and Ca content rate was 470 ppm.

Example 4
A graphite-silicon carbide composite was produced in the same manner as in Example 1 except that metal silicon powder having an Fe content of 7800 ppm, an Al content of 1520 ppm, and a Ca content of 1500 ppm was used as the thermal spray material.

  When the cross section of the obtained base material was observed and the surface layer was subjected to X-ray diffraction analysis, it was observed that a green silicon carbide layer was formed on the surface of the graphite base material as in Example 1.

  Next, in order to evaluate the oxidation resistance of the obtained graphite-silicon carbide composite, high temperature oxidation resistance was evaluated in the same manner as in Example 1. As a result, the weight loss was 4.2%, and it was confirmed that the material was excellent in high-temperature oxidation resistance. Moreover, when Fe, Al, and Ca content rate contained in a silicon carbide layer were measured, Fe content rate was 4800 ppm, Al content rate was 980 ppm, and Ca content rate was 900 ppm.

Example 5
A graphite-silicon carbide composite was produced in the same manner as in Example 1 except that metal silicon powder having an Fe content of 20 ppm, an Al content of 5 ppm, and a Ca content of 2 ppm was used as the thermal spray material.

  When the cross section of the obtained base material was observed and the surface layer was subjected to X-ray diffraction analysis, it was observed that a green silicon carbide layer was formed on the surface of the graphite base material as in Example 1.

  Next, in order to evaluate the oxidation resistance of the obtained graphite-silicon carbide composite, high temperature oxidation resistance was evaluated in the same manner as in Example 1. As a result, the weight loss was 4.0%, and it was confirmed that the material was excellent in high-temperature oxidation resistance. Moreover, when Fe, Al, and Ca content rate contained in a silicon carbide layer were measured, Fe content rate was 10 ppm, Al content rate was 3 ppm, and Ca content rate was 1 ppm.

[Comparative Example 1]
A graphite-silicon carbide composite was produced in the same manner as in Example 1 except that metal silicon powder having an Fe content of 2 ppm, an Al content of 5 ppm, and a Ca content of 2 ppm was used as the thermal spray material.

  When the cross-sectional observation of the obtained base material and the X-ray diffraction analysis of the surface layer were performed, a silicon carbide layer was formed on the surface of the graphite base material, which partially contained unreacted metallic silicon It was observed.

  Next, in order to evaluate the oxidation resistance of the obtained graphite-silicon carbide composite, high temperature oxidation resistance was evaluated in the same manner as in Example 1. As a result, the weight loss was 6.5%, and it was clearly confirmed that the high-temperature oxidation resistance was inferior to Examples 1-5. Moreover, when Fe, Al, and Ca content rate contained in a silicon carbide layer were measured, Fe content rate was 1 ppm, Al content rate was 3 ppm, and Ca content rate was 1 ppm.

[Comparative Example 2]
A graphite-silicon carbide composite was produced in the same manner as in Example 1 except that metal silicon powder having an Fe content of 8200 ppm, an Al content of 2000 ppm, and a Ca content of 2000 ppm was used as the thermal spray material.

  When the cross-sectional observation of the obtained base material and the X-ray diffraction analysis of the surface layer were performed, a silicon carbide layer was formed on the surface of the graphite base material, and partly Fe-Si alloy, Al-Si alloy, It was observed that a Ca-Si alloy was included.

  Next, in order to evaluate the oxidation resistance of the obtained graphite-silicon carbide composite, high temperature oxidation resistance was evaluated in the same manner as in Example 1. As a result, the weight loss was 10.3%, which was clearly confirmed to be inferior in high-temperature oxidation resistance as compared with Examples 1-5. Moreover, when Fe, Al, and Ca content rate contained in a silicon carbide layer were measured, Fe content rate was 6000 ppm, Al content rate was 1350 ppm, and Ca content rate was 1200 ppm.

  The results of Examples 1 to 5 and Comparative Examples 1 and 2 are summarized in Table 1 below.

表１において、各金属含有率の値は全てｐｐｍで示される。

In Table 1, all metal content values are shown in ppm.

  As described above, it has been clarified that the method for producing a graphite-silicon carbide composite of the present invention can provide a graphite-silicon carbide composite having excellent high-temperature oxidation resistance and less quality variation. . With such a graphite-silicon carbide composite of the present invention, the range of use as a heat-resistant material is widened and can be used for various applications.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

Claims (6)

  A graphite-silicon carbide composite having a graphite substrate and a silicon carbide layer formed on the surface of the graphite substrate, wherein the silicon carbide layer contains Fe, and the Fe content in the silicon carbide layer is A graphite-silicon carbide composite characterized by being 5 to 5000 ppm.   The graphite-silicon carbide composite according to claim 1, wherein the silicon carbide layer has a thickness of 10 to 300 μm.   The silicon carbide layer further contains Al and Ca, the Al content in the silicon carbide layer is 10 to 1000 ppm, and the Ca content is 5 to 1000 ppm. Graphite-silicon carbide composite. A method for producing a graphite-silicon carbide composite,
(1) preparing a metal silicon powder having an Fe content of 8 to 8000 ppm;
(2) spraying the metal silicon powder on the surface of the graphite substrate;
(3) heat treating the graphite substrate sprayed with the metal silicon powder in a temperature range of 1100 to 1700 ° C. in a non-oxidizing atmosphere to form a silicon carbide layer on the surface of the graphite substrate. A method for producing a graphite-silicon carbide composite.   5. The method for producing a graphite-silicon carbide composite according to claim 4, wherein the metal silicon powder has an average particle size of 0.5 to 50 μm.   In the step of preparing the metal silicon powder, the metal silicon powder further includes Al and Ca, the Al content is 16 to 1600 ppm, and the Ca content is 8 to 1600 ppm. Item 6. A method for producing a graphite-silicon carbide composite according to Item 4 or 5.