Tribochemical investigation of tungsten carbide/titanium alloy tribo-couples under aqueous lubrication

The present paper deals with the fundamental understanding on the tribochemical mechanism of tungsten carbide (WC) coating and titanium alloy tribo-couples system. The tribological experiments were performed with a Timken-type tester. Water containing water-soluble additives was employed as the lubricating media. The rubbed surfaces of the carbide coating were characterized with scanning electric microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Significant titanium transfer was observed. Results of XPS analyses show that the interfacial layers formed consist of multiple oxides which suggests that oxidative reactions predominate in frictional processes under aqueous lubrication. It is proposed that the oxide layer is responsible for the tribological behavior because it controls the diffusive and adhesive wear.