High Temperature Oxidation of β-SiC

The high temperature oxidation behavior of pressureless-sintered β-SiC samples containing 0.3wt%B and 1.8wt%C as sintering aids and small amounts of impurities were examined at 1400-1800K for 15h in Ar-O2 atmosphere. The oxidation reaction was followed continuously by measuring the evolved CO2 using a quadrupole mass spectrometer. The weight changes of the samples before and after the oxidation were measured and their oxidized surfaces were analyzed by SEM and ESCA. The oxidation behavior of β-SiC with B and C additives obeyed a parabolic kinetics. The amount of CO2 evolved, and the weight gain of the bodies increased with decreasing temperature. These results indicated that the crystallization of the silica layer formed on the surface of β-SiC occurred at high temperatures.