Corrosion of in-situ grown MgAl-LDH coating on aluminum alloy

MgAl-layered double hydroxides (LDH) coatings were fabricated by the in-situ hydrothermal treatment method on the AA5005 aluminum alloy. The characteristics of the coatings were investigated by XRD, FT-IR, SEM and EDS. The effect of the pH value of the solution on the formation of the LDH coatings was studied. The optimum pH value of the solution was 10.0. The corrosion resistance of the LDH coatings was studied using potentiodynamic polarization tests and electrochemical impedance spectrum (EIS). The results demonstrate that the LDH coatings, characterized by platelets vertically to the substrate surface possess excellent corrosion resistance. The influence of the hydrothermal crystallization time on the corrosion resistance was evaluated. Prolonging the crystallization time can increase the corrosion resistance of the obtained LDH coatings. The anticorrosion mechanism of the LDH coatings was discussed.