Preparation of Fine Grained SiC Layer by Fluidized Bed Chemical Vapor Deposition with Pulsed Propylene

A novel strategy named pulsed propylene method was developed to prepare fine grained SiC layer. The SiC layer was uniformly coated on ceramic microspheres by fluidized bed chemical vapor deposition. Propylene was introduced into the deposition system in pulsed form at proper time intervals. By adjusting the propylene concentration and the pulse interval, the grain size of SiC can be controlled from micrometer scale to nanometer scale and the microstructure of the SiC layer changed from large columnar grains to fine equiaxed grains. The SiC layer with average grain size less than 300 nm was obtained with the pulsed propylene under a volume concentration of 5% at an injection time interval of 2 min. The as-prepared fine grained SiC layer exhibited higher hardness and higher oxidation resistance than that of columnar grained SiC.