Surface engineering of Ti6Al4V surfaces for enhanced tribocorrosion performance in artificial seawater

Titanium and its alloys are materials with excellent corrosion resistant properties, but under sliding contact exhibit poor wear and friction performance. Therefore, the aim of this study was to find suitable surface treatments for titanium alloy substrates to be used under saline environmental conditions. Various surface engineering techniques have been applied to Ti6Al4V substrates, and the static corrosion performance of these surface treatments in presence of artificial seawater was evaluated using potentiodynamic investigations. Furthermore, the combined sliding-corrosion performance was investigated using a micro-tribometer coupled to an electrochemical cell. Using this set-up, the selected samples were tested in order to check the synergistic effect of wear and corrosion, also known as tribocorrosion. The results clearly revealed a poor tribological performance of the untreated Ti6Al4V substrate, thus highlighting the need for surface treatments. Furthermore, it was highlighted that some of the compared surface engineering treatments applied to Ti6Al4V although exhibited improved corrosion resistance under static conditions, they showed a radically different behaviour under tribocorrosion. The underlying reasons leading to a different tribocorrosion performance are discussed and the main mechanisms associated with surface degradation under combined wear and corrosion are revealed.