Oxidation behavior of the C/C composite coated by CVD-SiC in the N2, CO2 and H2O mixture gas

The influence of CO(2) and H(2)O gases on high temperature oxidation of CVD-SiC films on C/C composite are investigated in order to apply for the high temperature materials tu a methane fuel gas turbine. An oxidation test at 1,700 degrees C in an atmosphere containing large volumes of CO(2) and H(2)O gases is successfully attained by using the Xe-lamp heating method, and it is possible to measure the mass change of the specimen preventing the reaction at the contact spot with a sample holder. This paper describes that H(2)O gas hastens the beta-cristobalite transformation of the amorphous SiO(2) formed on the SiC film by high temperature oxidation, and this crystallization causes cracking of the SiO(2) films during cooling after heating, The oxidation rate of SIC is also accelerated by the existence of CO(2) and H(2)O in the atmosphere at 1,700 degrees C.