Surface treatment of tantalum to improve its corrosion resistance

Tantalum was treated by radio-frequency (r.f.) plasma technique in order to improve surface properties and corrosion resistance. In this study thin layers of tantalum carbide (TaC) were produced by inductive r.f. plasma-assisted chemical vapor deposition in a gas mixture of argon, methane and hydrogen. The effect of the hydrogen and methane concentrations on the fabricated layer was studied. It was observed that hydrogen played an important role in the acceleration of the carbon diffusion into the tantalum, and it enhanced the formation of TaC phase. Increasing the methane concentration in the gas mixture did not lead to a higher carbon supply to the surface; in fact, it reduced the formation of TaC phase. The properties of the fabricated layer, such as corrosion resistance, hydrogen adsorption content, and TaC:Ta2C phase ratio, are presented and discussed.