Stress-oxidation behavior of a carbon/silicon carbide composite in a high-temperature combustion environment

A carbon/silicon carbide composite with a silicon carbide coating was prepared by chemical vapor infiltration. Stressed oxidation testing was performed on the composites in a self-built high-temperature combustion environment. The gas in this environment contained oxygen, steam, carbon dioxide, and some nitrogen. Test conditions were controlled at temperatures of 1300°, 1500°, and 1800°C, and the stress was sustained at 40, 80, 120, 160, and 200 MPa. The effect of combustion environment and applied load on stress-oxidation behavior was discussed by analyzing the residual strength and weight loss. The morphology of the fracture surface of the tested specimens was observed by scanning electron microscopy. The high-temperature combustion environment and the high sustained stress above 80 MPa enhanced the material failure and led to strength reduction by determining crack openings and thus oxidation of fibers. However, sustained stress below 80 MPa resulted in no strength degradation after exposure for 10 min at 1500°C.