Effect of graphene oxide on micro-tribological and electrochemical properties of electrophoretically deposited HA-TiO2-GO composite coatings

Abstract

In the present study, hydroxyapatite-titania-graphene oxide (HA-TiO2-GO) nanostructured ternary composites were deposited on Ti-6Al-4V alloy by using electrophoretic deposition. The well-dispersed stable suspensions of hydroxyapatite particles with 20wt.% TiO2 and 0, 0.5, 1 and 2 wt.% GO were prepared and electrophoretic deposition was performed at an optimum voltage of 20 V for 90 s. A novel linear approach of fracturemechanics was applied to evaluate the fracture toughness of the coatings from the recorded forces and depth of penetration by using an incremental-load micro-scratch technique. The distances and contact pressures indicating crack formation and coating spallation, as well as the value of fracture toughness were obtained at the maximum level for the composite coatings with 20 wt.% TiO2 and 2 wt.% GO. The rapid apatite forming ability as well as improved corrosion resistance of the composite coatings with 20 wt.% titania and 2 wt.% GO were analysed by electrochemical impedance spectroscopy, SEM and XRD.