Passive-oxidation kinetics of SiC microparticles

We investigated the oxidation kinetics of SiC materials in the form of powders (average dimension 4 mum) in the temperature range 1100degrees-1500degreesC in dry air. The oxidation process was monitored through the relative mass gain in a thermobalance. As the specific surface area of the particles was measured, the recorded mass gain could be converted into the corresponding oxide thickness. The oxidation isotherms were fitted to a linear-parabolic equation, and the parabolic rate constant was evaluated. Up to 1400degreesC, temperature dependence can be described by a single activation energy of 179 kJ/mol, which increases in the 1400degrees-1500degreesC temperature range. These results are compared with the oxidation behavior of sintered polycrystalline and monocrystalline SiC materials.