Abstract
© 2022 Elsevier B.V.Combined the organic top-coats (Stearic acid (SA)) with inorganic salts (Cerium nitrate) sealing process, a novel sealing treatment was implemented on plasma electrolytic oxidation (PEO) coated 7085Al alloy to optimize the corrosion resistance in this work. The phase composition, surface morphology, wettability, roughness and electrochemical characterization results manifested that the sealing treatment was critical to the corrosion improvement. For the PEO-SA coating, the stearic acid should be chemically adsorbed on the PEO-SA coating after the sealing treatment. Herein, the stearic acid mainly reduced the surface energy of coating to achieve a hydrophobic structure, which was benefited to the corrosion resistance. Comparatively, the PEO-(SA + Ce) coating can further enhance anti-corrosion ability, which was attributed to the synergistic hydrophobic structure and sealing effects provided by Ce-based compounds. Finally, the underlying growth mechanisms of both coatings were proposed, and their corrosion behaviors were modelled and discussed analytically. Generally, this work has developed an efficient methodology to improve the corrosion resistance of protective coatings on Al alloys.
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