Outgassing characteristics of titanium with surface treatment of oxidation

For the purpose of investigating the outgassing characteristics of titanium, outgassing measurements by the conductance-modulation method for pure titanium and titanium alloy have been made. The surfaces of the chambers were treated with oxidation at 200degC and 450degC in an argon plus oxygen atmosphere after chemical polishing or mechanochemical buffing. The lowest outgassing rate of 5 x 10-9 Pa m3s-1 m-2 after 50 hr pumping was measured on a pure titanium chamber by oxidation treatment at 200degC. Surface analyses such as TEM were also done on test samples treated in the same conditions as the chambers. Oxidation treatment at 200degC is effective to obtain a low outgassing surface for titanium because of its thin and amorphous oxide film, which was observed by these surface analyses. (author)