Growth of SiC thin films on graphite for oxidation-protective coating

We have deposited thick SiC thin films on graphite substrates in the temper ature range of 700-850 degrees C using single-molecular precursors by both thermal metal-organic chemical-vapor deposition (MOCVD) and plasma-enhanced MOCVD (PEMOCVD) methods for oxidation-protection wear and tribological coa ting. Hexamethyldisilane (HMDS), (CH3)(3)Si-Si(CH3)(3), was used as a singl e-source precursor, and hydrogen and Ar were used as a bubbler and carrier gas. A highly oriented polyerystalline cubic SiC layer in the [111] directi on was successfully deposited on graphite at temperatures as low as 800 deg rees C with HMDS by PEMOCVD. For thermal MOCVD, on the other hand, only amo rphous SiC layers were obtained at 850 degrees C. From this study, we confi rmed that PEMOCVD was a highly effective process in improving the character istics of the SiC layers compared to those grown by thermal MOCVD. The mech anical and oxidation-resistant properties have been assessed. The optimum S iC film was obtained at 850 degrees C and rf power of 200 W. The maximum de position rate and microhardness are 2 mu m/h and 4336 kg/mm(2) Hv, respecti vely. The hardness was strongly influenced by the composition ratio of the SiC protective layers. (C) 2000 American Vacuum Society. [S0734-2101(00)182 04-1].