JPH0578173A - Production of functionally gradient silicon carbide/ carbon material - Google Patents

Abstract

PURPOSE:To provide a method for producing a functionally gradient silicon carbide/carbon material having composition ratio of silicon carbide to carbon gradient in relation to cross section. CONSTITUTION:A functionally gradient silicon carbide/carbon material is produced by the following method. Several kinds of carbon fibers having different reactivities with silicon are prepared and carbon fiber 1 having higher reactivity is laminated from the surface layer in regular order and impregnated with carbon 3 to be a matrix to prepare a carbon-fiber reinforced carbon composite material 4. Silicon is then successively diffused and permeated from the surface layer in which the carbon fiber having higher reactivity with the above- mentioned composite material is present.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a silicon carbide / carbon functionally gradient material in which the composition ratio of silicon carbide and carbon is graded with respect to the cross section.

[0002]

2. Description of the Related Art Since conventional carbon fiber reinforced carbon composite materials use only carbon fibers having low reactivity with silicon, even if silicon is diffused and penetrated from the surface layer to form silicon carbide,
Since carbon fibers are less likely to become silicon carbide and carbon remains near the surface, the carbon fiber reinforced carbon composite material has insufficient oxidation resistance.

[0003]

Since the conventional method uses only carbon fibers having low reactivity, the reaction between carbon and silicon in the carbon fiber reinforced carbon composite material is mainly caused by the matrix even if silicon is impregnated from the surface. Since the impregnated carbon which is the above is generated, and the carbon fiber is hard to react, nonuniformity occurs in the inclination.

In view of the above-mentioned state of the art, the present invention aims to provide a method of manufacturing a silicon carbide / carbon gradient function to which a uniform gradient function is provided.

[0005]

According to the present invention, several kinds of carbon fibers having different reactivity with silicon are prepared in advance, the carbon fibers having higher reactivity than the surface layer are laminated in order, and carbon as a matrix is impregnated with the carbon fibers. A method for producing a silicon carbide / carbon functionally gradient material, which comprises producing a reinforced carbon composite material, and then diffusing and penetrating silicon from a surface layer of the composite material where highly reactive carbon fibers are present.

[0006]

The carbon fiber having high reactivity is placed on the surface layer of the carbon fiber reinforced carbon composite material and impregnated with silicon. Therefore, like the impregnated carbon as the matrix, the carbon fiber becomes silicon carbide and uniform silicon carbide is formed. Generated in the surface layer.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. When the carbon fiber reinforced carbon composite material 4 is manufactured, the carbon fiber 2 having a low reactivity with silicon inside is used as the carbon fiber.
The highly reactive carbon fiber 1 is arranged on the surface layer, and carbon serving as the matrix 3 is impregnated. Next, the surface layer is impregnated with silicon, and the silicon is reacted with the matrix 3 and the highly reactive carbon fiber 1 in the surface layer portion to form silicon carbide 5 as shown in FIG.

As a result, more silicon is impregnated in the surface layer,
Since it gradually decreases inward, a functionally graded silicon carbide / carbon layer 6 is formed on the material cross section. As a method of impregnating silicon, for example, a method of burying in a mixed powder of silicon powder, aluminum oxide powder, and silicon carbide powder and subjecting to high temperature heat treatment in vacuum to impregnate silicon can be mentioned.

[0009]

EFFECTS OF THE INVENTION By forming a functionally graded layer on the surface of a carbon fiber reinforced carbon composite material, a silicon carbide / carbon functionally graded material in which the linear expansion coefficient is continuously graded can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view of a carbon fiber reinforced carbon composite material used in one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a silicon carbide / carbon functionally gradient material obtained in one example of the present invention.

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Claims (1)

[Claims] 1. A carbon fiber-reinforced carbon composite material is prepared by preparing several kinds of carbon fibers having different reactivities with silicon, laminating the carbon fibers having higher reactivity than a surface layer in order, and impregnating carbon as a matrix. Then, a method for producing a silicon carbide / carbon functionally gradient material, characterized by diffusing and penetrating silicon from the surface layer of the composite material, on which highly reactive carbon fibers are present.