Construction of lubricant composite coating on Ti6Al4V alloy using micro-arc oxidation and grafting hydrophilic polymer

To improve the tribological properties of Ti6Al4V alloy to realize the application in artificial joints, a novel composite coating was designed and fabricated on its surface through the combination of two different surface modification techniques micro-arc oxidation (MAO) and grafting hydrophilic polymer. The characterizations of morphologies and composition of MAO layer were examined using scanning electron microscopy (SEM), energy dispersive spectroscope (EDS) and X-ray diffraction (XRD). It was found that a TiO2 layer displaying uniform porous structure formed on the surface based on the optimal MAO parameters of an oxidation voltage of 450 V and an oxidation time of 60 min. After grafting 3-dimethyl(3-(N-methacrylamido)propyl) ammonium propane sulfonate (MPDSAH), Fourier-transform infrared spectroscopy with attenuated total reflection (FT-IR/ATR) and wettability test demonstrated the successful modification. Tribological performance of composite coating modified Ti6Al4V alloy in water exhibited the low friction coefficient of 0.13 and favorable wear resistance.