Thermal Stability of Glass-Sealed Si-Ti-C-O Fiber Reinforced SiC Composite

Abstract

Thermal stability of glass-sealed Si-Ti-C-O fiber reinforced SiC composite was investigated by exposed at 1200°C for 200 hours in air. The composite consisted of 40 vol% 3-D surface-modified Si-Ti-C-O fabric and SiC matrix formed by polymer impregnation and pyrolysis (PIP) method. The surface of the composite was glass(SiO2-Na2O)-sealed using a proprietary technique, which is not costly method, for improving oxidation resistance of the composite. After the exposure, the flexural strength at room temperature retained nearly 90% of the strength of the as-fabricated, exhibiting fiber pull-out and crack-deflection. The flexural strength of the exposed composite at 1200°C in air decreased to less than half of the strength of the as-fabricated, however, re-seal of the glass after the exposure was effective and the flexural strength of the re-sealed composite at 1200°C in air improved to 80% of the strength of the as-fabricated. These results indicated the glass-sealed Si-Ti-C-O fiber reinforced SiC composite could be applicable to components which serve at high temperatures in air.