Decrease of water vapor desorption by Si film coating on stainless steel

Surface modification of stainless steel by Si coating was attempted to reduce water desorption in an evacuation process. Outgassing properties of stainless steel plates with and without Si coating including dependence on deposition condition were compared by temperature programmed desorption and throughput method. The outgassing rate of a Si coated sample at optimized condition was reduced to about 1/10 of the electrolytically polished 304L-type stainless steel plate at room temperature. The most reduced outgassing species was water. H-2 and CO2 were also reduced at the same time. The Si film was amorphous and the surface was covered with about an 8 nm thick oxide layer. (C) 1999 Elsevier Science Ltd. All rights reserved.