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

Abstract

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.