Synthesis of ZIF-67 film in micro-arc oxidation anticorrosion coating on AZ31 magnesium alloy

In order to improve the corrosion resistance of AZ31 magnesium (Mg) alloy and the adhesion of metal-organic frameworks (MOFs) coating, a MAO/ZIF-67 (Co-based MOFs) (micro arc oxide/ZIF-67) composite coating was fabricated by in-situ growth on AZ31 MAO coating. The results showed that ZIF-67 with rhombic dodecahedron uniformly grew on the surface of MAO coating, and exhibited good adhesion to the substrate, which made MAO/ZIF-67 composite coating have good corrosion resistance. It was proved that ZIF-67 could effectively seal the pores of MAO coating, increase the tortuosity of the invasion path of corrosion medium, and significantly improve the corrosion resistance of Mg alloy. In addition, MAO pretreatment gave the coating strong adhesion, which was more conducive to ZIF-67 sealing micro-pores. This study is of great significance to reduce the limitation of MOF coating applied to all metal substrates.