Effects of Graphene Oxide on Tribological Properties of Micro-Arc Oxidation Coatings on Ti-6Al-4V

This paper investigates the effect of graphene oxide (GO) particles on the friction reduction and wear resistance of coatings on a Ti-6Al-4V alloy generated using the micro-arc oxidation (MAO) technique. Different concentrations of GO were added in aluminate-phosphate electrolyte. The composition of the MAO coatings was investigated using X-ray diffraction and the energy dispersive spectrum. Measurements of the coating's thickness, hardness, and roughness have also been conducted. Ball-on-disk friction tests under dry conditions were carried out to reveal the tribological behavior of the MAO coating. The results showed that the coating consisted of Al2TiO5 and gamma-Al2O3. The addition of GO greatly reduced the friction coefficient by 25%. The coating with 5 g/L of GO particles exhibited the lowest friction coefficient (reduced from 0.47 to 0.35). Moreover, the coating thickness become thicker (from 10 to 20 mu m) with an increase in GO concentration from 0 to 10 g/L. The wear mechanism was revealed via worn surface analysis. This study provides a helpful way to improve the surface wear resistance of titanium alloys.