Microstructure and Tribological Performance of Micro-Arc Oxidation Coating on Ti6Al4V Alloy.

A micro-arc oxidation (MAO) coating was in–situ grew on Ti6Al4V alloy to improve the friction-wear performance, and the morphologies, chemical compositions and phases of obtained coating were analyzed using a scanning electron microscope, energy dispersive spectroscopy, and X–ray diffraction, respectively. The effect of normal load on the tribological performance of MAO coating at 400 °C was investigated on a ball–on–disc wear tester. The results show that the MAO coating exhibits irregular–pore structure, which is mainly composed of TiO₂ phase. The coefficient of friction (COF) and wear rate of MAO coating under the normal load of 2 N are 0.32 and of 0.84 × 10^–5 mm³ N⁻¹ m⁻¹, respectively, showing the best friction reduction and wear resistance among the three kinds of loads. The wear mechanism of MAO coating under the normal load of 2 N is abrasive wear; while those under the normal loads of 4 and 6 N are adhesion wear fatigue wear, respectively, in which the MAO coating has the tendency of plastic deformation with the increase of normal load. [ABSTRACT FROM AUTHOR]