Brazing of alumina ceramics and pure titanium

Alumina ceramics vacuum Chamber which is used for the 3 GeV rapid-cycling synchrotron (RCS) in J-PARC is composed of alumina duct, titanium (Ti) flanges and Ti sleeves. Before brazing the alumina duct and the Ti sleeves, the Ti sleeves were treated with Nitric acid-Hydrofluoric acid. The purpose of this study is to clear the effect of this treatment for titanium material. It was cleared that the roughness of the titanium material after the Nitric acid-Hydrofluoric acid treatment becomes big for SEM observation. It was also measured that the thickness of oxide film on surface of the titanium material was 12.7 nm before treatment and 6.0 nm after treatment. As a result of measuring the wettability of the brazing material which was silver brazing filler metal (Ag: 72%, Cu: 28%) on the Ti surface and the diffusion of the Ti material into the brazing material, it became clear that the vacuum condition of the vacuum heating furnace was important for brazing between alumina ceramics and pure titanium. (author)