Influence of particle size distribution on oxidation behavior of SiC powder

Oxidation kinetics of SiC powder was investigated using thermogravimetry (TG) analysis in the temperature range from 1623 to 1673 K. XRD and optical microscopy were also employed to investigate the morphological development during the oxidation. The kinetic analysis indicated that the oxidation reaction was passive at oxygen atmosphere and the morphological development of the cross-section of SiC powder during oxidation did not change much compared with the raw material. Based on the experimental data, a new kinetic equation for describing the isothermal oxidation process with diffusion-controlled is deduced, in which the influence of particle size distribution of SiC on the reaction rate has been taken into account. When this equation was applied to the experiment of oxidation of SiC powder, it showed that the experimental data could be fitted very well. The activation energy of oxidation of SiC powder is obtained to be 270 kJ/mol. (C) 2008 Elsevier B.V. All rights reserved.