News Coatings Technologies
Synergistic PEO and LDH pre-treatments enhance adhesion and corrosion protection on AA2024-T3
A combined surface treatment using plasma electrolytic oxidation (PEO) and in situ grown LDH conversion layers significantly improves the adhesion and corrosion protection of organic coatings on AA2024-T3 aluminium.
Researchers investigated a combined pre-treatment strategy to strengthen the performance of organic coatings on AA2024-T3. The approach used a dual anodic process: conventional anodising followed by an energy-efficient plasma electrolytic oxidation step, reducing energy consumption by 41 % and forming a 40 μm thick PEO layer. A MgAl layered double hydroxide (LDH) conversion coating was then formed in situ on top of the PEO layer.
Characterisation of roughness, crystalline structure, morphology and composition confirmed a well-developed protective layer. Corrosion resistance was evaluated via electrochemical impedance spectroscopy (EIS) on both uncoated and epoxy-coated samples.
Reading tip: Corrosion protection coatings
The book Anticorrosive Coatings: Fundamentals and New Concepts brings together all the disciplines involved in the creation and use of corrosion protection coatings for metals. It presents the latest insights into the quality and chemistry of surfaces, the proper way to prepare them by conversion treatment, the function of resins and anticorrosion pigments in paints, and novel concepts in corrosion protection. As an added bonus, all the standards and directives mentioned in the text are grouped together in their own chapter for a better overview.
Improved wet adhesion and long-term performance
The PEO-LDH-Epoxy system exhibited superior wet adhesion and enhanced corrosion protection after 28 days in 3.5 wt% NaCl. The LDH treatment also delayed the emergence of the low-frequency time constant, indicating a more stable barrier. The synergistic effect of PEO and LDH outperformed the stand-alone PEO system.
The study demonstrates that tailored multi-step surface treatments can effectively improve interface stability and long-term corrosion resistance of organic coatings on high-strength aluminium alloys.
Source: Iqbal, M. A. et al., Synergy of consecutive PEO and LDH surface treatments on the corrosion protection and adhesion strength of organic coatings on AA2024-T3. Progress in Organic Coatings 207, 109397 (2025).
