Corrosion resistance study of ZIF-67/Co-Fe LDHs composite coating on the surface of AZ31 magnesium alloy micro-arc oxidation film

Magnesium (Mg) alloys can be applied in many fields, but their poor corrosion resistance limits their widespread applications. This study prepared a zeolitic imidazolate framework (ZIF-67)/Co-Fe layered double hydroxides (LDHs) composite coating on micro-arc oxidation (MAO) coated Mg alloy AZ31. The surface, interface, and corrosion resistance of the composite coating were studied. The results demonstrate that the ZIF-67/LDHs composite coating showed lower corrosion current density icorr (1.31×10-8 A∙cm–2) than AZ31 (5.20×10-5 A∙cm–2), MAO (1.16×10-7 A∙cm–2) or LDHs (7.78×10-8 A∙cm–2). After immersing in a 3.5 wt.% NaCl solution for 14 days, its icorr still remained the lowest, exhibiting excellent corrosion resistance to AZ31. It was of great significance in improving the corrosion resistance of Mg alloys, and this compositely growth technology was expected to be applied to other metals.