Synthesis of TiO₂/rGO composite coatings on titanium alloys with enhanced anticorrosion performance in palmitic acid-incorporated physiological solutions

During plasma electrolytic oxidation (PEO) process, molten oxide is rapidly solidified through arc discharges in order to create in-situ ceramic TiO₂ coatings on titanium alloy substrates. PEO coatings made on biomedical titanium alloys may have limited protection efficiency in organic acid-containing biological solutions due to their inherent porosity. In order to elevate the anticorrosion performance of these coatings, a second layer can be applied to the top surface of the PEO coatings to seal the cracks and pores by other surface engineering methods. In current work, the reduced graphene oxide (rGO) nanosheets were electrophoretically deposited on the Ti–6Al–4V substrate involving an intermediate TiO₂ oxide layer applied PEO process. Electrochemical measurements in palmitic acid-containing biological media showed that the duplex TiO₂/rGO coating has higher compactness and better corrosion performance than simple TiO₂ coating. Indeed, the synthesis of the TiO₂/rGO coating on the Ti alloy results in a decrease in the corrosion current density (2.19 μA‧cm⁻²) in comparison with the simple TiO2 coating (9.85 μA‧cm⁻²) in an acidic media.