The corrosion and tribocorrosion resistance of PEO composite coatings containing α-Al2O3 particles on 7075 Al alloy

Abstract Plasma electrolytic oxidation (PEO) of 7075 Al alloy was carried out in silicate base electrolyte containing 200 nm diameter α-Al2O3 particles for producing composite coatings. The process was performed under a soft-sparking regime using a pulsed bipolar signal with several concentrations of α-Al2O3 particles. It was found that the incorporation of α-Al2O3 particles into the coating did not significantly alter the thickness and roughness of the coating. However, the α-Al2O3 particles were detected on surface of the composite coatings. Corrosion tests showed significant improvement in corrosion performance of the composite coatings due to the efficient pore blocking provided by α-Al…