Microstructure and corrosion performance of zeolite/MAO-coated Al alloy

For micro-arc oxidation (MAO) coating on aluminium alloys, the corrosion medium can permeate through the microvoids and cracks in it to decrease its corrosion resistance. In this study, a method of two-steps hydrothermal synthesis has been developed to prepare a composite coating by the synthesis of zeolite film on MAO-coated Al alloy substrate. The zeolite crystals are well intergrown into a continuous film and the micro defects in the MAO coating are sealed. This kind of composite coating can provide excellent long-term corrosion protection to Al alloy substrate. The effect of the first-step hydrothermal synthesis on the microstructure of the MAO coating and zeolite film has been studied.