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oai:docta.ucm.es:20.500.14352/1050352025-09-18T14:32:00Zcom_20.500.14352_14col_20.500.14352_15

00925njm 22002777a 4500 dc Del Olmo Martínez, Rubén author López, E. author Matykina, Endzhe author Tiringer, U. author Mol, J.M.C. author Mohedano Sánchez, Marta author Arrabal Durán, Raúl author 2023 Plasma electrolytic oxidation (PEO) has been targeted as an eco-friendly alternative technology to conventional chromic acid anodizing (CAA) for corrosion protection of aluminium alloys in the aircraft industry. However, conventional PEO technology implies high energy consumption. Flash-PEO coatings (≤10 μm) produced in short treatment times (≤ 5 min) constitute a feasible way to overcome this limitation. Nevertheless, the long-term corrosion resistance is compromised, thus requiring novel sealing post-treatments. The present work studies the effect of stand-alone hybrid sol-gel (HSG) and Ce-doped hybrid sol-gel (HSGCe) coatings as a sealing post-treatment to evaluate the long-term corrosion resistance of Flash-PEO coatings on aluminium alloy (AA) 2024-T3. The characterization of the PEO, HSG, and HSG-Ce coatings was performed by scanning electron microscopy, X-ray diffraction, water contact angle, dry adhesion tests (ISO 2409), optical profilometry and Fourier transform infrared spectroscopy. The corrosion behaviour was assessed by electrochemical impedance spectroscopy up to 21 days (3.5 wt% NaCl). Active corrosion protection was assessed by immersion tests of artificially scratched coatings. Present findings reveal that low-energy-cost Flash-PEO coatings were successfully formed on AA2024-T3 alloy. Both HSG and HSG-Ce coatings were homogeneously formed on Flash PEO coating. Regarding the corrosion resistance, HSG-Ce showed significant scratch protection during 21 days of immersion in 3.5 wt% NaCl. The results suggest that, while the release of Si and Ce from the coating provided corrosion protection, NO3−release promoted localized corrosion phenomena in the scribe. This was associated with the preferential pitting corrosion phenomena at the Cu-rich intermetallic compounds instead of forming a thick and stableNO3−-rich passive layer. R. del Olmo, E. López, E. Matykina, U. Tiringer, J.M.C. Mol, M. Mohedano, R. Arrabal, Hybrid PEO/sol-gel coatings loaded with Ce for corrosion protection of AA2024-T3, Progress in Organic Coatings, Volume 182, 2023, 107667, ISSN 0300-9440, https://doi.org/10.1016/j.porgcoat.2023.107667 (https://www.sciencedirect.com/science/article/pii/S0300944023002631) 0300-9440 10.1016/j.porgcoat.2023.107667 https://hdl.handle.net/20.500.14352/105035 https://doi.org/10.1016/j.porgcoat.2023.107667 https://www.sciencedirect.com/science/article/pii/S0300944023002631 Hybrid PEO/sol-gel coatings loaded with Ce for corrosion protection of AA2024-T3