JPH08151283A - Coating on graphite and heat-resistant material - Google Patents

Abstract

PURPOSE: To provide a method for producing a coating film excellent in heat resistance at a low cost on graphite and to obtain a heat-resistant material. CONSTITUTION: An organic compound infiltrative into pores 15 of a graphite material 11, e.g. a graphite-based bonding agent 12 is mixed with Si-powder 13 which forms a carbide and an oxide powder 17 which forms an oxide. The mixture is applied on the surface of a graphite material 11 and treated at a high temperature. By this treatment, a carbon component in a graphite matrix (bonding agent 12) reacts with a metallic component and forms a ceramic-mixed layer 18 consisting of carbide and oxide whose surface is coated with a layer 19 of high concentration of oxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a carbide, a ceramic or the like for reducing the reactivity of graphite when the molten metal and graphite are reactive or when graphite is used in a high temperature oxidizing atmosphere. TECHNICAL FIELD The present invention relates to a method for coating graphite with a coating material and a heat-resistant member formed by the coating method.

[0002]

2. Description of the Related Art A coating method for graphite is used for various melting and casting processes, a film forming process that requires a metal melting process such as vacuum deposition, and a heat-resistant member used in the atmosphere. is there.

Silicon carbide (hereinafter referred to as S
iC. In general, the following methods are available. Immerse the graphite part in the molten Si metal,
React carbon of graphite and Si. CVD (Cemical Vapor Deposition) method or C
Coating is performed by the VR (Cemical Vapor Reaction) method.

However, generally, it is not easy to firmly bond a ceramic material to a graphite part, and the method has not been established.

[0005]

Among the above-mentioned coating methods, the one which is immersed in a molten metal such as Si has the following problems. That is, the SiC film can be formed on the entire surface of the graphite member, but it is not necessary to form the film, for example, the bolt holes of the product are made into Si.
This is difficult to apply when the graphite surface is used without carbonization, or when one surface of the product is the graphite surface. Further, when the surface of the graphite on which the SiC film is formed is further ceramic-coated, it becomes difficult to coat the mixed phase of SiC and oxide.

On the other hand, the coating method using the CVD method or the like has a problem that the cost becomes high in addition to the problems similar to those described above.

Furthermore, when forming an oxide-enriched layer of ceramics or the like on the surface of graphite, it is difficult to coat the surface layer of simple graphite, and in order to improve the adhesion, for example, a SiC layer is used as an intermediate layer. However, there is a problem that the compatibility between SiC and oxide is poor and only a thin film can be coated.

The present invention solves such problems, and an object of the present invention is to provide a method for coating graphite, which is inexpensive and has excellent heat resistance, and a heat-resistant member.

[0009]

The method for coating graphite of the present invention to achieve the above object is a metal which forms a carbide in an organic compound-based adhesive having permeability between the pores of graphite. It is characterized in that the powder is mixed, the mixture is attached to the surface of the graphite material, and the mixture is heated at a high temperature to react the carbon component of the graphite base with the metal component to form a carbide layer.

In the method for coating graphite of the present invention, an organic compound-based adhesive having permeability between pores of graphite is mixed with a metal powder and an oxide for forming a carbide, and the mixture is mixed with graphite. By adhering to the surface of the material and heat-treating at high temperature, the carbon component of the graphite base and the metal component are reacted to form a ceramic mixed layer of carbide and oxide, and an oxide concentrated layer is formed on the surface of the ceramic mixed layer. Is formed.

In the heat-resistant member of the present invention, a mixture of a metal powder and an oxide which forms a carbide is adhered to the surface of the graphite material in an organic compound adhesive having permeability between the pores of graphite, A ceramic mixed layer of carbide and oxide is formed on the surface of the graphite material by reacting a carbon component and a metal component of the graphite base by heating at a high temperature, and an oxide concentrated layer is formed on the surface of the ceramic mixed layer. Is formed.

[0012]

[Function] When a carbide layer is formed on the surface of graphite, high temperature treatment is performed with a mixture of an organic compound, for example, a graphite-based adhesive and a metal powder that generates carbide, being attached to the surface of the graphite material. Then, the base carbon component and the metal component react with each other, the generated carbide permeates between the pores of the graphite, and a strong carbide layer is formed on the surface of the graphite.

Further, in the case of coating the surface of graphite with a ceramic, a high temperature treatment is carried out with a mixture of an organic compound, for example, a graphite-based adhesive and a metal powder and an oxide for forming a carbide adhered to the surface of the graphite material. By doing so, the carbon component of the base and the metal component react, the generated carbide penetrates into the pores of the graphite, and a strong carbide layer in which the oxide is mixed is formed on the surface of the graphite. Then, the ceramic coating is completed by coating an oxide-enriched layer on the surface of the carbide layer, and since the oxide-enriched layer is formed as a mixed layer of carbide and oxide, it is easy to be familiar and a thick film is formed. Coating is possible.

The heat-resistant member formed by the ceramic coating method comprises a graphite material, a mixed layer of carbide and oxide firmly formed on the surface of the graphite, and a thick film formed on the surface of the mixed layer. It is composed of an oxide-enriched layer and is inexpensive and has excellent heat resistance.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In the method for coating graphite of the present invention, in the crucible for molten metal, etc., the reaction between the molten metal and the graphite is prevented at the portion where the molten metal and the graphite material come into contact, and the graphite The purpose of the material is to prevent oxidation of the surface at high temperature, and a carbide such as SiC or a ceramic mixed film of carbide and oxide such as SiC is formed on the surface of the graphite material. Then, since it reacts with the substrate and the metal powder that has penetrated into the pores of the substrate to form a carbide, the anchor effect between the film and the substrate is large, and the adhesion is good.

FIG. 1 shows an outline of a method for coating graphite according to an embodiment of the present invention. (A) shows a state in which a mixture of a graphite-based adhesive and Si powder is applied to the surface of a graphite material, ( b) shows a state in which the SiC layer is formed by firing this at an appropriate degree of mixing.

In this embodiment, as shown in FIG.
SiC as a carbide layer on the surface of graphite material 11
In the case of forming only a layer, a graphite-based adhesive (for example, a Kopuna resin-based adhesive) 12 and an Si powder 13 as a metal powder of a carbide to be formed are mixed in appropriate amounts to form a mixture, and a mixture is generated as shown in FIG. ), The mixture is applied to a required portion of the graphite material 11 by brush or spray. Then, after coating, firing is performed at an appropriate temperature to form a carbide of SiC (SiC layer 14) as shown in FIG.

At this time, the bondability of the graphite-based adhesive 12 with the graphite 11 and the permeability into the graphite pores 15 are utilized. That is, the Si powder that forms carbide is bonded to the surface of the graphite 11 together with the adhesive 12 and penetrates into the pores 15 of the graphite 11. Then, during firing, the carbon component (C) in the adhesive 12 and the graphite 11 react with the metal component Si to generate a carbide (SiC), and the whiskers 16 are generated. In this way, a strong SiC layer is formed on the surface of the graphite material 11.

FIG. 2 schematically shows a graphite coating method according to another embodiment of the present invention, in which a mixed layer of SiC and oxide is formed and an oxide concentrated layer is formed on the surface thereof. Indicates.

In this embodiment, as shown in FIG.
First, when a mixed layer of carbide and oxide is formed on the surface of the graphite material 11, the graphite-based adhesive 1
An appropriate amount of Si powder 13 and oxide powder 17 as the metal powder of the carbide to be formed with 2 is mixed to form a mixture, which is applied to the surface of graphite material 11. Then, the mixed layer 18 is formed by firing at an appropriate temperature. That is, the SiC layer 14 containing the oxide 17 is firmly formed on the surface of the graphite material 11 by the whiskers 16.

Next, when the surface of the graphite material 11 on which the SiC layer 14 is formed is coated with the oxide-enriched layer 19, the oxide 17 contained in the SiC layer 14 makes it easier for the surface to become compatible with the oxide. This oxide enriched layer 1
Coat 9. This enables thicker film coating than in the past.

In the above embodiments, the graphite-based adhesive was used as the organic compound, but the present invention is not limited to this. Further, although the carbide layer (SiC layer) 14 or the mixed layer 18 of carbide and oxide is formed on the surface of the graphite material 11 by the coating method on graphite, it is also possible to form a mixed layer of carbide and nitride. Is.

[0024]

As described above with reference to the examples, according to the method for coating graphite of the present invention, a mixture of an organic compound-based adhesive and a metal powder that forms a carbide is applied to the surface of the graphite material. By treating the carbon component of the base material and the metal component in the adhered state at a high temperature to form a carbide layer on the surface of the graphite, the generated carbide permeates between the pores of the graphite to form the graphite layer. A strong carbide layer can be formed on the surface of.

Further, according to the method for coating graphite of the present invention, a mixture of an organic compound-based adhesive, a metal powder for forming a carbide and an oxide is subjected to a high temperature treatment while being adhered to the surface of the graphite material. By reacting the carbon component of the base with the metal component, a carbide layer containing oxides is formed on the surface of the graphite, and the oxide concentrated layer is coated on the surface of the carbide layer. The concentrated layer is formed as a mixed layer of carbide and oxide, and can be easily adapted to form a thick film coating.

As a result, the surface of graphite is inexpensive,
In addition, it is possible to provide a coating method which has good workability, is excellent in resistance to molten metal, or is excellent in reactivity with the environment, and can limit the coating location.

Further, according to the heat-resistant member of the present invention, a mixture layer of carbide and oxide is formed on the surface of graphite, and an oxide concentrated layer is formed on the surface of this mixture layer. It is possible to prevent the reaction with graphite, prevent the surface from being oxidized at high temperature, and improve the heat resistance.

[Brief description of drawings]

FIG. 1 is a schematic view of a method for coating graphite according to an embodiment of the present invention, in which (a) is a state diagram in which a mixture of a graphite-based adhesive and Si powder is applied to the surface of a graphite material, (b) ) Burns this at the proper temperature and adds S
It is a state diagram in which an iC layer is formed.

FIG. 2 is a schematic view showing a method for coating graphite according to another embodiment of the present invention, in which a mixed layer of SiC and an oxide is formed and an oxide concentrated layer is formed on the surface thereof.

[Explanation of symbols]

 11 Graphite 12 Graphite-based Adhesive 13 Si Powder 14 SiC Layer 15 Graphite Pore 16 Whiskers 17 Oxide Powder 18 Mixed Layer 19 Oxide Concentration Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashige Shigeji 1-1-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. Takasago Research Institute (72) Tomikane Saida 2-chome, Niihama, Arai-cho, Takasago, Hyogo Prefecture No. 1 Mitsubishi Heavy Industries, Ltd. Takasago Laboratory (72) Inventor Ichigo Mori 2-1-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Mitsubishi Heavy Industries Ltd., Takasago Laboratory

Claims (3)

[Claims] 1. A method of mixing a metal powder capable of forming a carbide with an organic compound adhesive having permeability between pores of graphite, adhering the mixture to the surface of the graphite material, and performing heat treatment at a high temperature. A coating method for graphite, which comprises forming a carbide layer by reacting a carbon component of a graphite base with a metal component by means of. 2. An organic compound-based adhesive having permeability between pores of graphite is mixed with a metal powder and an oxide for forming a carbide, and the mixture is adhered to the surface of the graphite material and heated at a high temperature. By treating, a carbon component and a metal component of the graphite base are reacted to form a ceramic mixed layer of carbide and oxide, and an oxide concentrated layer is formed on the surface of the ceramic mixed layer. Coating method. 3. A graphite is prepared by adhering a mixture of a metal powder and an oxide which forms a carbide to an adhesive of an organic compound having permeability between pores of graphite, on a surface of a graphite material, and heat-treating at a high temperature. By reacting the carbon component and the metal component of the base, a ceramic mixed layer of carbide and oxide is formed on the surface of the graphite material, and an oxide concentrated layer is formed on the surface of the ceramic mixed layer. And heat resistant material.