Study on the Characteristics of MAO/Polymer/Ni Three-Layer Composite Film formed on AZ31 Magnesium Alloy

In this study, MAO/Polymer/Ni three-layer composite coating deposited on AZ 31 magnesium alloy was carried out by micro-arc oxidation, spinning coated and eletroless Ni processes. The characteristics of different coatings were analyzed by XRD, SEM, TEM and EDS. The MAO film subsequent sealing with polymer layer, the polymer agent will fill up the micro-arc holes of MAO film. Finally, an electroless nickel layer were deposited on polymer film to form a MAO/polymer/Ni composite coating. It can significantly decrease the icorr value from 39.6x10(-6) A/cm(2) to 7.2x10(-6) A/cm(2). The MAO/polymer/Ni coating significantly enhanced the corrosion resistance of the AZ31alloy due to the protection performance both of polymer and nickel layer.