Thermal stability and mechanical properties of SiC particulate-reinforced Si-C-N composites after heating at 2000 °C

摘要

A SiC particulate-reinforced Si-C-N ceramic composite was fabricated using the precursor impregnation and pyrolysis method, and its thermal and mechanical properties were analyzed. The weight loss of the composite was 5% after a heating at 2100 °C in Ar. The pores of the composite enlarged at and above 1700 °C in Ar due to the decomposition of the Si-C-N matrix. However, the composite retained mechanical properties such as strength and hardness after heating at 1700 °C. 88% of the original strength was remained after heating at 2000°C for 10h although the fabrication temperature was 1350 °C. The weight gain of the composite was 3.2% after an oxidation at 1450 °C for 30 min in air. The inner oxidation of the particulate-reinforced composites (PRC) was suppressed above 1400 °C due to the closure of the open pores by SiO_2. Consequently, the composite possessed excellent creep resistance at 1400 °C in air. The SiC/Si-C-N composite is a challenging candidate for the application at high temperature.