Abstract
As application of SiC-coated molybdenum to the first wall components of a fusion reactor has begun to attract much attention from the view point of plasma contamination. Silicon carbide films up to 12μm in thickness was synthesized for this purpose by RF glow discharge of the mixture of Si vapor and C2H2 gas. The deposits were characterized by X-ray diffraction, electron microprobe analysis, Auger electron spectroscopy and IR absorption spectroscopy. Control of Si/C ratio of the deposits was readily achieved only by changing the substrate temperature, holding the other coating process variables constant. Nearly stoichiometric SiC was found to be formed at the deposition temperature of 800°C, when silicon was evaporated at a rate of about 0.04g min-1 under an acetylene gas pressure of about 5×10-3 Torr. Preliminary examination on thermal stability of the deposits showed that a mixture of C+SiC was desirable rather than stoichiometric compound only. The inclusion of free silicon in the film seemed to be responsible for the degradation of nearly stoichiometric film above 1300°C. The synthesis mechanism of SiC films in the RF reactive ion platig was also discussed mainly by the ductility change and fractography of the molybdenum substrate coated under various coating conditions.
