Effect of physical barrier and anion-exchange process of nitrate-intercalated ZnAl layered double hydroxide films grown on Al on corrosion protection

ZnAl layered double hydroxide (ZnAl-LDH) film loaded with nitrates was prepared on the surface of pure Al plate by hydrothermal reaction. The anion-exchange process of ZnAl-LDH in corrosive NaCl solution was demonstrated by the X-ray Diffraction (XRD). The corrosion protection behavior of this fabricated film was monitored by performing electrochemical impedance spectroscopy (EIS) up to 39 d. It was revealed that the physical barrier effect of nitrate-intercalated ZnAl-LDH film played a significant role in its corrosion protection and the anion-exchange had a limited influence on final corrosion protection. •XRD was used to characterize the anion-exchange behavior of LDH films.•The corrosion behavior was studied by continuous monitoring changes of EIS and XRD.•The physical barrier effect of ZnAl-LDH was significant in its corrosion protection.•The anion-exchange had a limited influence on corrosion protection in this system.