Formation Kinetics of Surface Oxidation Film of Corundum-silicon Nitride Composites

The formation mechanism of oxidation film on the surface of corundum-silicon nitride composites were investigated by means of Paucity thermobalance,XRD and SEM.The starting materials were corundum and silicon nitride powder.The kinetics equation has been worked out.The results showed that the formation kinetics of oxidation flim at the surface of the composites included three stages.Control by chemical reaction-the kinetics equation is △W=Kc·t,in which Kc=52.21exp(-73806.3/RT).Mixed control-the kinetics equation is (△W)2+KO/Kc(△W)=Km·t,in which Km=253.81exp(-85644.2/RT) control by diffusion rate-the kinetics formula is (△W)2=Kd·t,in which Kd=31.12exp(-66522.1/RT).