A Novel Surface Treatment to Selectively Harden TI6AL4V Surfaces

Various surface treatments have been developed on Ti 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 pre-painting TiO 2 powder and thermal oxidation. It is found TiO 2 powdered layer can be used as an oxygen reservoir for boost diffusion treatment at a temperature 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. Pre-painting the surfaces that need to be hardened is easily operated and has good potential to be applied in industry.