An enhanced ceramic conversion treatment of Ti6Al4V alloy surface by a pre-deposited thin gold layer

A novel approach to produce a hard ceramic hard layer on the surface of Ti6Al4V alloy in a more efficient way was developed in this research. A thin layer of gold was pre-deposited on a Ti6Al4V alloy before ceramic conversion treatment (CCT), and the gold particles accelerated the thermal oxidation of Ti6Al4V alloy especially in the beginning period and produced a smoother and harder surface. Surface morphologies, microstructure and elemental compositions of the samples before and after treatment were characterised by SEM, EDX, and XRD. The role of the gold in the rapid oxidation and a potential mechanism have been elucidated. The mechanical properties of the surfaces were assessed by microhardness, scratch and reciprocating friction and wear tests. Fine dispersed gold nanoparticles and clusters in the oxide layer of the pre-deposited Ti6Al4V samples were found, and they had much better tribological properties in terms of reduced coefficient of friction and wear volume than those samples treated by conventional long duration thermal oxidation treatments without a pre-deposited gold layer. The anti-bacterial properties were improved significantly.