Thermal stability and mechanical properties of SiC particulate-reinforced Si-C-N composites after heating at 2000 deg 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 percent after a heating at 2100 deg C in Ar. The pores of the composite enlarged at and above 1700 deg 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 deg C. 88 percent of the original strength was remained after heating at 2000deg C for 10h although the fabrication temperature was 1350 deg C. The weight gain of the composite was 3.2 percent after an oxidation at 1450 deg C for 30 min in air. The inner oxidation of the particulate-reinforced composites (PRC) was suppressed above 1400 deg C due to the closure of the open pores by SiO_2. Consequently, the composite possessed excellent creep resistance at 1400 deg C in air. The SiC/Si-C-N composite is a challenging candidate for the application at high temperature.