Growth and corrosion resistance of MgAlZn-LDH/SC coatings on Mg-Li alloy

In order to further enhance the corrosion resistance of magnesium-lithium alloys, the LDH / SC composite coating (Layered double hydroxide / Steam coating) were prepared on the surface of LA103Z alloy by two-step method of steam pretreatment and in-situ hydrothermal treatment. The morphology, thickness, structure, and corrosion resistance of MgAlZn-LDH/SC composite coating under different hydrothermal solution concentrations were studied. It is shown that the MgAlZn-LDH/SC composite coating prepared on LA103Z Mg-Li alloy consists of uniform and dense nanolayers, which can provide good corrosion resistance to the substrate. The corrosion current density of the MgAlZn-LDH/SC film layer is two orders of magnitude lower than that of the Mg-Li alloy matrix. The combination of the results from the two hydrogen precipitation and immersion experiments demonstrates that the corrosion resistance of the MgAlZn-LDH/SC composite coating is significantly enhanced in comparison to that of the substrate. The coating prepared at a concentration of 0.09 M Al(NO 3 ) 3 + 0.07 M Zn(NO 3 ) 2 exhibits the best corrosion resistance.