Oxidation resistance of Si-coated TZM alloy prepared through combined process of plasma spray and laser surface melting

Plasma thermal spraying of Si coating layer on titanium-zirconium-molybdenum (Ti-Zr-Mo), TZM alloy, was conducted for the surface protection of the Mo substrate that is unstable in air at high temperatures. Although the plasma thermal spraying alone could protect the Mo alloy from oxidation at a high temperature for a short time, the post laser surface melting process further improved the oxidation resistance of Si-coated alloy. In the case of the post laser treated specimen, MoSi compounds, mainly MoSi2 phases, were formed during the additional annealing process, and the oxidation resistance could be even further enhanced. The corrosion behaviors of Si-coated specimens in 3.5% NaCl solution were also investigated; however, no significant variations with respect to the post treatment procedure were found.