Impact of the amount of the gold layer on the tribological performance of the ceramic conversion treated CP-Titanium

Titanium alloys are characterised by poor tribological properties, and a ceramic TiO₂ layer formed on the surface can greatly improve its performance. By pre-depositing a gold layer on the titanium surface, the gold particles promoted the outward diffusion of titanium in the ceramic conversion treatment to react with the inward-coming oxygen to form a compact titanium dioxide layer. The surface morphology, microstructure, and phase constituents were characterised by SEM/EDX and XRD. The adhesion of the oxide layers was assessed by a scratch test. The distribution of gold particles in the oxide layer enhanced the surface hardness and reduced the friction and wear against a WC (tungsten carbide) ball in the reciprocal tribological test. The ceramic conversion process was accelerated efficiently at 620-660°C, and the more gold pre-deposited, the thicker the oxide layer.