Carbon coatings on silicon carbide by reaction with chlorine-containing gases

Carbon films were formed on the surface of beta-SiC particles by reaction with Ar-Cl2 and Ar-Cl2-H2 gas mixtures at atmospheric pressure and temperatures of 600-1000 C. The structure and composition of the carbon films were studied using XRD, SEM, EDS, TEM, FTIR and Raman spectroscopy. BET and TG were also used for measuring the amount of carbon formed in the reaction. Uniform nanoporous carbon films with surface area exceeding 1000 m2/g were obtained by reactions with Ar-Cl2 gas at 600-1000 C. Based on Raman spectroscopy and electron diffraction data, these films were identified as nanocrystalline graphite. Addition of H2 to the gas mixtures results in the etching of graphitic carbon. Traces of diamond were found along with amorphous carbon after treatment in Ar-Cl2-H2 gas mixtures at temperatures above 900 C. 30 refs.