In this paper, the influence of SiO2 on the microstructure and consolidation mechanism of recrystallized silicon carbide (RSiC) was studied by comparing the relationship of the weight losses and microstructural evolution with the SiO2 contents at different firing temperatures. The results showed that the presence of SiO2 resulted in a basic weight loss proportional to the SiO2 content and an additional weight loss independent of the SiO2 content. The consolidation mechanism of SiC was not altered by the introduction of SiO2, involving surface diffusion at low temperatures and an evaporation-condensation process at the high temperature, while the residual ambient atmosphere primarily including SiO(g), Si2C(g) and Si(g) inhibited the recrystallization of SiC by altering the mass transport from SiC2(g), Si2C(g) and Si(g) for pure SiC to that combined with the gaseous transport of SiO(g), Si2C(g), Si(g) and SiC(g), and the surface diffusion of C(s) at the high temperature.

Keywords: Recrystallized Silicon Carbide, SiO2, Microstructure, Evaporation-Condensation.