Synthesis, characterization and anticorrosion performance of molybdate pillared hydrotalcite/in situ created ZnO composite as pigment for Mg–Li alloy protection

Nano-sized molybdate pillared hydrotalcite (HT-MoO42−)/ZnO incorporated composite (HTMZ), was successfully synthesized by in situ co-precipitation method. To prepare the materials, a given amount of molybdate sodium was adjusted at pH 10.0 with NaOH and then mixed with a second solution, containing Zn(NO3)2·6H2O and Al(NO3)3·9H2O with metal ratio Zn2+/Al3+of 2.5. The physicochemical properties of the samples were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and inductively coupled plasma (ICP), respectively. The primer coating containing HTMZ was formed on Mg–Li alloy using epoxy resin. This work presents the comparative corrosion protection performance of the coating containing HTMZ with the coating containing nano ZnO or HT-MoO42− using Electrochemical impedance spectroscopy (EIS) measurement and salt spray test. Results indicate that the coating containing HTMZ has higher corrosion resistant property. The mechanism of corrosion protection was proposed to be that the existent ZnO promote molybdate aggradation on alloy surface.