An Efficient Micro-arc Oxidation Technology for AZ80 As-cast Magnesium Alloy

A highly efficient micro-arc oxidation treatment method and relevant electrolyte were developed for AZ80 as-cast magnesium alloy. The traditional micro-arc oxidation treatment time was shortened to 3 min, and an oxide ceramic film with good corrosion resistance was prepared on the surface of AZ80 magnesium alloy. The structure of oxide ceramic membrane on the surface of AZ80 magnesium alloy was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The corrosion resistance and corrosion process of the ceramic layer were studied by salt spray corrosion test and electrochemical test. The results showed that after 3 min micro-arc oxidation treatment, a 6 μm thick ceramic film was formed on the surface of AZ80 magnesium alloy, and the main components of the film were magnesia, magnesium silicate and magnesium meta-aluminate. The corrosion resistance of the AZ80 magnesium alloy covered by a ceramic oxide film was improved by more than 4 orders of magnitude compared with the matrix, and exhibitted good corrosion resistance in the long-period 5% neutral salt spray corrosion test.