Thermal oxidation kinetics of CrSi2 powder synthesized by pack cementation process

Abstract

Chemical vapor deposition by pack cementation process was used for the first time for the synthesis of CrSi2 powder. The as-prepared powder was characterized by X-ray powder diffraction and scanning electron microscopy. It was indicated that the product was hexagonal CrSi2, while the crystallite size was estimated by Williamson–Hall equation at 32.5 nm. Non-isothermal oxidation, from room temperature to 1473 K in air, indicated that the compound was stable up to 963 K. Fractional conversion was also calculated from mass change of the samples during isothermal oxidation at four different temperatures. A number of kinetic models and calculation procedures were used to determine the values of the kinetic parameters of the oxidation process. It was found that the reaction could be best described by three-dimensional Ginstling and Brounshtein diffusion model.