Abstract: A carbon fiber reinforced carbon of the present invention is composed of a sintered body comprising precursor carbonaceous fiber and self-sintering carbonaceous powder with the precursor carbonaceous fiber buried therein. Since the precursor carbonaceous fiber working as a reinforcement and the self-sintering carbonaceous powder working as a binder come to have substantially the same physical properties (strength, shrinkage rate and the like), the boudary adhesion between them improves, thereby giving the sintered body high strength and excellent abrasion resistance. When the precursor carbonaceous fiber is subjected to a surface treatment using a viscous material, the wettability of the surface of the precursor carbonaceous fiber increases, thereby further improving the boundary adhesion between the precursor carbonaceous fiber and the self-sintering precursor carbonaceous powder.

Abstract: A piston ring preform is formed with a groove dividing its cylindrical outer surface, and this groove is filled up by plasma-spraying with a deposit of alloy whose surface is flush with the cylindrical outer surface of the preform not deposited with alloy. The alloy is about 55%-70% Cr, about 3%-9% C, and balance Fe. In preferred embodiments the groove has a bottom and side walls which are inclined at at least 100.degree. to one another, and a sub-layer composed of metal powder plasma-sprayed under the alloy deposit such that it adheres well to the bottom of the groove and which has good heat and oxidization resistance. The material of the preform may be cast iron, nodular graphite cast iron, or steel; and the material of the sub-layer may be a mixture of Ni and Al.