Oxidation Kinetics of MgO-SiC Composites

摘要

The oxidation kinetics of particulate-reinforced MgO composites have been studied. The rate of growth of the oxidized layer and the changes in microstructure that occur suggest that Mg~(2+) diffusion is the rate controlling step. To confirm that magnesium diffusion is rate-controlling, SiC-reinforced MgO doped with scandium was oxidized under similar conditions. Sc_2O_3-doping increased the rate of oxidation as expected compared to the pure reinforced MgO. Oxidation in ~(18)O_2 confirms the mechanism as does the formation of an oriented large-grain surface layer.