Effect of oxidation and residual stress on mechanical properties of SiC seal coated C/SiC composite

The effect of oxidation and thermal residual stress on mechanical properties of SiC seal coated C/SiC composite at ambient temperature and high temperature were studied. The oxidation of SiC seal coated C/SiC composite at 1300 and 1500 °C resulted in carbon fibres burn area near through thickness micro cracks in the SiC seal coating. With the increase in exposure time, the formation of SiO₂ layer in SiC matrix near carbon fibres burns area was found. Residual mechanical properties of SiC seal coated C/SiC composite after exposure in air show significant degradation. First time, a continuous measurement of Young's modulus with temperature of C/SiC composite was carried out using an impulse excitation technique. The effect of relaxation of thermal residual stress on mechanical properties was observed with the help of continuous measurement of Young's modulus as a function of temperature in an inert atmosphere.