Effects of temperature and duration on oxidation of ceramic composites with silicon carbide matrix and carbon nanoparticles

This paper was to investigate the oxidation behavior of three pressureless sintered ceramic composites of silicon carbide (SiC) matrix with various contents of carbon nanoparticles (Cp) (i.e., 0, 15 and 25 wt%) at various temperatures (i.e., 600-1100 °C) and durations (i.e., 2-12 h). The results indicate that the oxidation of SiC/Cp ceramics in air is uniformly controlled by the oxidation of Cp at <700 °C, and the strength of the samples reaches a minimum value at 700 °C. At 700-900 °C, the oxidation is controlled via the unequal diffusion of O2 through the micro-cracks. The oxidation of SiC/Cp is controlled by O2 diffusion through the structural defects of the matrix at 900-1100 °C, and the strength of the composites increases at 1000 °C and reaches a maximum value during the initial period of 2 h due to the formation of SiO2 layer and the healing of the matrix defects.