Hybrid PEO–hydrothermal–silane coating with synergistic Ce–8HQ inhibitor sealing for durable corrosion protection of AZ31 magnesium alloy

Abstract Coatings with long-term corrosion protection capabilities have attracted considerable attention for enhancing the surface performance of magnesium (Mg) alloys in industrial applications. In this study, plasma electrolytic oxidation (PEO) coatings were further sealed using cerium (Ce) via hydrothermal (HT) treatment, followed by the application of a silane layer containing 8-hydroxyquinoline (8HQ). The results demonstrate a synergistic corrosion-inhibiting effect between CeO x and 8HQ, resulting in nearly a 100-fold enhancement in polarization resistance after 16 days of immersion in 3.5% NaCl. Additionally, the H 2 evolution rate decreased by 80% compared to the unsealed PEO coating after 30 days of immersion.