Abstract
© 2022 Elsevier B.V.Thin plasma electrolytic oxidation (PEO) coating was produced on 2024 aluminum alloy as pre-treatment process, which was subsequently treated by hydrothermal method to grow layered double hydroxide (LDH) layer to seal the open pores and defects to enhance corrosion performance of the oxide layer. Vanadate and molybdate was exchanged and loaded into LDH layer to further improve the corrosion resistance of the composite coating. The porous PEO coating was sealed substantially after growth of LDH, although thickness of the composite layer was reduced due to dissolution during post-treatment process. Exchange of inhibitors can greatly enhance the corrosion performance of the coating. The impedance of vanadate containing coating was maintained in the level of 106 Ω·cm2 for 20 days during immersion in 3.5 wt% NaCl solution and showed superior corrosion protection for Al surface after performing neutral salt spray test for 60 days.
NSTL