Investigation of enhanced corrosion resistance in Zn-Al coating via novel ZIF-8/LDH composite films

Purpose This study aims to enhance the corrosion resistance of Zn-Al coating by synthesizing ZIF-8/LDH composite films. Design/methodology/approach Zn-Al LDHs films were synthesized via hydrothermal method, followed by preparation of ZIF-8/LDH composite films through coordination substitution. Characterization was done using X-ray diffraction, electron probe microanalysis, atomic force microscopy and transmission electron microscopy. Corrosion resistance was evaluated using electrochemical impedance spectroscopy and polarization curves in 3.5 Wt.% NaCl solution. Findings The results show that dense ZIF-8/LDH composite films with thicknesses of 20.8–23.5 µm and wetting angles of at least 108° were successfully prepared on the Zn-Al coating. The self-corrosion current and Rct of samples with ZIF-8/LDH films increased by two orders of magnitude. ZIF-8/LDH composite films demonstrated protection efficiency exceeding 98.62%. Originality/value This study introduces a novel method to improve the corrosion resistance of Zn-Al coating using ZIF-8/LDH composite films. The findings highlight the superior performance of composite films with a Zn/Al molar ratio of 6:1, offering new insights into their structural and anticorrosive properties.