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.