Mechanical properties of oxidation-resistant SiC/C compositionally graded graphite materials

Abstract

Mechanical properties of oxidation-resistant SiC/C compoaitionally graded graphite materials composed of a CVD SiC coating layer, a SiC/C graded layer, and a graphite substrate were studied by bending, compresseive, and hardness tests at room temperature. CVD SiC coated graphite and graphite with a SiC/C graded layer alone were also examined. The bending strengths of oxidation-resistant SiC/C compositionally graded graphite materials as well as CVD SiC coated graphite were about twice as much as that of graphite. The bending and compressive strengths of graphite with the SiC/C graded Layer alone were almost the same as those of graphite. The higher strengths of graphite with the CVD SiC layer can be mainly due to the CVD SiC strength itself. and partly doe to the smooth CVD surface. No effect of the SiC/C layer on the strengths was discussed to terms of porosity, surface morphology, and the strength of SiC.