Correlation between synthesis conditions and corrosion behavior of nickel–aluminum layered double hydroxide (LDH)-sealed anodized aluminum

Abstract AA2024 is widely employed within the aerospace sector; nevertheless, its susceptibility to pitting upon exposure to chloride ions presents a notable challenge. This investigation proposes an in-situ co-precipitation technique for effectively sealing the anodic oxide layer on the AA2024 substrate by nickel–aluminum layered double hydroxides (LDH) conversion coating. Given the lack of reported data concerning the correlation between the nucleation/growth behavior and the anti-corrosion performance of NiAl-LDH coatings, the current research aimed to investigate the effect of synthesis conditions including temperature and pH on the morphology and nucleation of LDH nanoplatelets, as well as the corrosion resistance of prepared coatings. Field-emission SEM, atomic force microscopy, X-ray diffraction analysis, electrochemical measurements, Raman, FT-IR, and X-ray photoelectron spectroscopy were utilized to study the behavior of coatings. The results indicated that the prolonged nucleation/growth stage of synthesized NiAl-LDH nanoplatelets at pH 7.5 improves the electrochemical performance through providing a compact LDH coating.