JIA Lintao, WANG Mengqian, ZHU Jie, LI Aijun, PENG Yuqing
(School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China)
Abstract: Silicon carbide (SiC) coatings were prepared by using chemical vapor deposition (CVD) with a vertical hot-wall reactor and trichloromethylsilane-hydrogen-nitrogen (MTS-H2-N2) precursor. The effect of processing parameters on deposition rates of the SiC layers was studied. The SiC coating on the SiC fiber was characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Morphology and crystal structure of the SiC coatings were investigated. The SiC deposition rate was increased firstly and then decreased with increasing temperature in the range of 850-1050 ℃. At 1000 ℃, the deposition kinetics transferred from surface reaction control to mass transfer control. As the partial pressure of the reactant was increased to 30 kPa, the SiC deposition rate was increased. The deposition process was changed from surface active site adsorption to nucleation and growth. With increasing residence time, the SiC deposition rate was gradually decreased. The SiC coating was smooth and compact. The SiC deposited at 850-1050 ℃ was β-SiC. The main gas-phase species after MTS pyrolysis were CH4, C2H2, SiHCl3, SiCl2 and SiCl4.
Key words: chemical vapor deposition; silicon carbide; deposition rates; gas-phase species