Abstract
The surface treatment, which improves outgassing property for the titanium materials, was examined in this paper. A chemical polishing using a nitric acid solution was found to be the most suitable for the titanium materials, because the polished titanium has a surface roughness of 1.80 nm in a microscopic range of 1 micro m and thin oxide surface layer thickness of 7 nm, and the polishing solution has stability and workability. And the surface processing for the titanium was developed by the combination of the chemical polishing and the precision cleaning. The chemically polished pure titanium of JIS grade 2 showed excellent outgassing rate below 10^-12 Pa m s·1 after baking process, which is two orders of magnitude smaller than that for standard vacuum materials under the same baking condition. Outgassing rates of the titanium is about 1/6 of that for a stainless steel without baking process.
