A Novel Treatment to Selectively Harden Ti6Al4V Surfaces

Various surface treatments have been developed on titanium and its alloy to improve their tribological properties. However, for some components, only specific surfaces need to be hardened rather than the whole surfaces. This study develops a duplex heat treatment including selective surface hardening by prepainting TiO2 powders and thermal oxidation. It is found that the TiO2 powder layer can be used as an oxygen reservoir for boosting diffusion treatment at temperatures of 800–900 °C. The abundance of oxygen provides high potential and accelerates the diffusion process, deeply hardening the surface case. Moreover, the duplex treatment is optimal for selectively hardened surfaces with high load-bearing capacity and much improved tribological properties. Prepainting the surfaces that need to be hardened is easy to operate and has good potential to be applied in industry.