Abstract: A silicon carbide-based porous structure material maintaining the shape of a cardboard or sponge-like porous structure, with a great relative surface area, and a process for producing the same, is provided. To this end, a cardboard or sponge-like shaped framework of silicon carbide-based porous structure material is impregnated with a slurry comprising a resin, as a carbon source, and silicon powder, and subjected to reactive sintering in a vacuum or inert atmosphere, or in a nitrogen gas atmosphere, generating silicon carbide. At the same time pores are generated due to volume reduction reaction, thereby allows obtaining a silicon carbide-based porous structure material with a great relative surface area. Furthermore, excess carbon is removed from the fabricated silicon carbide-based porous structure material, and impregnated with a solution which becomes an oxide ceramic coating upon firing, whereby oxidization resistance is excellent and relative surface area is markedly improved.

Abstract: A ceramic material comprising a double phase complex sialon sintered body of .beta.'-type sialon and O'-type sialon being composed of the four elements of Si,Al,O and N and having a ratio of .beta.'-type sailon/O'-type sialon of 7/1 to 3/5 by weight ratio.The .beta.'-phase-O'-phase complex sailon has a dense structure and is excellent in high strength and high oxidation-resistance.

Abstract: A process for producing a .beta.-sialon.silicon carbide complex includes mixing silicon nitride and silicon carbide with an aluminum alkoxide solution or a soluble aluminum salt solution and using the resulting homogeneous mixture as a starting material in forming a sintered body. The aluminum alkoxide solution or aluminum salt solution penetrates into the surface of each particle of the silicon nitride and silicon carbide, whereby the whole surface of each nitride and carbide particle is covered with aluminum alkoxide solution or aluminum salt solution, and homogeneous mixing is achieved. Therefore, defects such as pores, clusters of large grains, or unsintered parts are eliminated and the strength of the final sintered bodies is improved.