EFFECT OF DEPOSITION CONDITIONS ON THE PROPERTIES OF PYROLYTIC SILICON CARBIDE COATINGS FOR HIGH-TEMPERATURE GAS-COOLED REACTOR FUEL PARTICLES

摘要

Silicon carbide coatings on HTGR microsphere fuel act as the barrier to contain metallic fission products. Sili¬con carbide coatings in this study were applied by the decomposition of CH3SiCl3 in a 13-cm-diam (5-in.) fluidized-bed coating furnace. The effects of temperature, CH3SiCl3 supply rate and the H2:CH3SiCl3 ratio on coating properties were studied. Deposition temperature was found to control coating density, whole particle crushing strength, coating efficiency, and microstructure. Coating density and microstructure were also partially determined by the H2:CH3SiCl3 ratio. From this work, it appears that the rate at which high quality SiC can be deposited can be increased from 0.2 to 0.5 um/min.