J. Phys. IV France 12 (2002) Pr4-113
Unveiling the magic of H 2S on the CVD-Al 2O 3 coating. Effect of H 2S on the water gas concentrationT. Oshika, M. Sato and A. Nishiyama
Mitsubishi Materials Corporation, Central Research Institute, Naka Research Center, 1002-14 Mukohyama, Naka-machi, Naka-gun, lbaraki-ken 311-0102, Japan
The aim of this work is to investigate the role of H 2S-doping in the CVD-Al 2O 3 coating process. It is well known that H 2S-doping into the CVD-Al 2O 3 coating process improves thickness uniformity around the substrate, and enhances the deposition rate of an Al 20 3 layer. The source gas mixture of general CVD-Al 2O 3 Coating comprises AICl 3, C0 2 and H 2, wherein Al 20 3 is produced by the hydrisis reaction of AlCl 3 and H 2O that is produced through the "water gas shift reaction, H2 + C02 -+ H2O + CO". The concentration of CO in the CVD reactor was investigated using gas tester for the gas mixture of H 2 and C0 2 that produces CO along with the same amount of water. It was suggested that H 2S-doping enhanced the formation of H 2O only when surrounding surface was comprised from CVD-coated Al 20 3, meanwhile H 2O formation was significantly restrained by that doping when surrounding surface was other materials such as SiO 2, stainless steel and sintered Al 20 3.
© EDP Sciences 2002