Electrochemical Response of Al₂O₃-MoO₂-TiO₂Oxide Films Formed on 6061 Al Alloy by Plasma Electrolytic Oxidation

The purpose of this study is to investigate the electrochemical response of Al 2 O 3 -MoO 2 -TiO 2 oxide films fabricated on 6061 Al alloy by plasma electrolytic oxidation (PEO). The coatings were fabricated under alternating current conditions using an alkaline-silicate-molybdate electrolyte with TiO 2 , and the results were compared to those without TiO 2 . Microstructure observations revealed that when TiO 2 was added to the electrolyte, the average size and area fraction of the micro-pores of the oxide layer coated in the electrolyte incorporating TiO 2 were respectively smaller. The results of potentiodynamic polarization test in 3.5 wt% NaCl solution clearly indicated that the corrosion resistance of the oxide films was significantly improved by the incorporation of TiO 2 particles. High corrosion resistance of the Al 2 O 3 -MoO 2 -TiO 2 oxide films was also revealed by impedance tests and analyzed in relation to the equivalent circuit model.