PURPOSE: To apply an oxidation-resistant coating provided with good environmental stability, high strength, high toughness, etc., to the surface of a carbonaceous matrix by forming a platinum layer on the surface of the carbonaceous matrix used for the outer wall of a space equipment and subsequently subjecting the formed platinum layer to a siliconizing treatment.

CONSTITUTION: A pasty platinum coating is coated on the surface of a carbonaceous matrix 1 (e.g. C/C composite) used for the outer wall of a space equipment, etc., heated in an inert gas atmosphere for the evaporation of a solvent, etc., and subsequently sintered to form a platinum layer 2. The formed platinum layer is subjected to a siliconizing treatment comprising a diffusion-thermal treatment in a mixture powder of silicon, silicon carbide and alumina to form a platinum silicide layer 2a in which the silicide is made to diffuse into the platinum layer 2. The silicide further diffuses into the carbonaceous material 1 through the platinum layer 2 to form a silicide diffusion layer 3, thus applying the oxidation-resistant coating to the carbonaceous matrix 1. Thereby, the generation of cracks caused by thermal stresses or mechanical deformations can be prevented, because the platinum silicide layer 2a has an excellent thermoplastic deformation constant.