Oxidation and mechanical behavior of SiC coated C/C composites made by Si impregnation method

SiC coated C/C composites were formed by the processing route of the Si melt impregnation method, SMIM, under various temperature. The oxidation behavior and strength of the coated C/C composites made by the SMIM were then examined to clarify advantages of this method. From the viewpoint of oxidation resistance, the SIC coating formed by the optimal condition of the SMIM is shown to be superior to the conventional CVD methods. It is especially true when the heat treatment temperature of the SMIM is low, i.e., just above the melting temperature of Si. Underlying mechanisms of this superior oxidation resistance were explained in terms of the variation of the coating thickness and coating crack opening. By the SMIM treatment the interlaminar shear strength was also improved remarkably but the bending strength was found to be degraded noticiably. It was suggested to be rather difficult to relieve the bending strength degradation by changing the SMIM treatment condition.