Low Friction Achieved on Plasma Electrolytic Oxidized TC4 Alloy in the Presence of PAO Base Oil Containing MoDTC

Surface engineering is required to improve the poor lubrication performance of titanium alloys in many applications. In this study, an oxide coating with high-hardness was created on TC4 titanium alloy by using plasma electrolytic oxidation (PEO). The composition and structure of the PEO coatings were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. The tribological properties of the PEO-treated TC4 were investigated in the presence of a polyalphaolefin (PAO) base oil with addition of molybdenum dialkyldithiocarbamate (MoDTC). The results show that the PEO-treated TC4 exhibits excellent lubrication performance in the presence of MoDTC. The oxide coating on the PEO-treated TC4 sample shows a tribo-induced catalysis effect enabling the decomposition of MoDTC to forms an effective lubricating film containing MoS2, resulting in reduced friction and wear.