Tribology, surface chemistry and morphology of WS2 tribofilms generated by the ANS triboconditioning process

Abstract

Triboconditioning is a mechanochemical surface finishing process developed for improving the tribological properties of mechanical components made of steel or cast iron. The process combines elements of extreme pressure mechanical burnishing of the component surface with a tribochemical deposition of a low-friction anti-wear film of tungsten disulphide (WS2). This allows one to produce, in a single finishing operation, a smoother surface with a significantly reduced coefficient of boundary friction and improved wear-resistance and load-carrying capacity. This study presents results of tribological rig tests carried out with valve train components and cylinder bores that underwent the triboconditioning treatment. The results show significant improvement in the tribological properties of triboconditioned components. The improvement is attributed to the formation of WS2 tribofilms at the component surface and a modified surface roughness profile with reduced core roughness (Rk) and peak height (Rpk). Elemental composition of the tribofilms generated by the triboconditioning process has been studied by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy the surface profile of the treated components has been studied using vertical scanning interferometry and the internal structure of the tribofilms has been studied with focused ion beam-transmission electron microscope technique. © 2013 John Wiley & Sons, Ltd.