Enhancing corrosion resistance and microstructure of the PEO coating layer on 6061 aluminium alloy: The role of first step voltage in plasma electrolytic oxidation

In this study, a novel two-step hybrid PEO technique was used to produce an alumina(Al2O3) on an Al6061 alloy. The research emphasizes the influence of the microstructure of the initial thin layer on the amount of defects such as microcracks and micropores in the final coating. Initially, a thin alumina layer was formed at 400 ~ 600 V using a pulsed unipolar mode, followed by a thicker layer at 500 V using a pulsed bipolar mode. The results indicate that a sound PEO coating with fewer defects markedly enhances the corrosion resistance of the Al6061 alloy.