Plasma electrolytic oxidation of Al alloy 5083-O was carried out in a dilute alkaline electrolyte with a unipolar pulsed DC condition. The coatings were fabricated with different process time (10, 20, 30 and 40 min) and were characterized for surface morphology, phase composition, and corrosion resistance. It was found that increasing process time resulted in an increase in thickness of the coating. However, longer duration of coating period did not result in an improvement of corrosion resistance. In this study, 10 min of process time is determined to be the optimum condition to improve corrosion resistance, resulting in two orders of magnitude lower corrosion current density compared to the substrate

Keywords: Plasma electrolytic oxidation, Ceramic oxide, Alumina, Process time, Corrosion resistance, Surface modification.