Suppression of hydrogen absorption to V–4Cr–4Ti alloy by TiO2/TiC coating

Titanium oxide film was coated on the surface of a V–4Cr–4Ti alloy to reduce hydrogen absorption at low temperature region. Titanium oxide was deposited by rf reactive magnetron sputtering with a titanium target using oxygen as sputter gas. The film consisted of a mixture of TiO2 and TiC. The content of TiO2 was approximately 80%. The atomic composition remained the same in the temperature range below 873 K. The film thickness also remained the same in the temperature region below 773 K. At the temperature higher than 973 K, the oxygen concentration decreased due to diffusion into the bulk of V-alloy, and the carbon concentration increased due to diffusion from the bulk of V-alloy. The hydrogen absorption rate of Ti-oxide coated V-alloy decreased with increase of the film thickness. In the case of the film with the thickness of 0.5 μm, the absorption rate was much smaller than that of non-coated V-alloy at the absorption temperature of 573 K.