Surface modification of titanium alloys for combined improvements in corrosion and wear resistance

A simple and effective surface modification technique, namely palladium-treated thermal oxidation (PTO), has been developed in the present research. Comparative investigations on both corrosion and wear resistance have been carried out on surface-engineered titanium-based materials by conventional plasma nitriding (PN), thermal oxidation (TO), and the newly developed palladium-treated thermal oxidation (PTO). Both the TO- and PTO-treated materials have a significantly superior corrosion resistance in boiling HCl solutions compared to the PN-treated and untreated materials. The lifetime for the protective surface layer breakdown of the TO-treated titanium in boiling 20% HCl solution is about 13 times that of the PN-treated titanium, whereas the lifetime of the PTO-treated material has been increased fruther by a factor of 2.6 over the TO-treated material. The PTO-treated material has shown a better anti-scuffing capacity than the TO-treated material under oil-lubricated conditions. Characterisation of both the TO- and PTO-treated surface layers was performed using glow discharge spectrometry (GDS), X-ray diffraction (XRD) and scanning electron microscopy (SEM).