Efficient Micro-Arc Oxidation Technology for As-Cast AZ80 Magnesium Alloy

Abstract

A new efficient micro-arc oxidation technology was developed for AZ80 magnesium alloy, the treating time was shorten to 3 min compared to the conventional micro-arc oxidation process. The surface morphologies and cross section morphology of the coatings were analyzed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). The corrosion behavior and process of the coatings were investigated with potentiodynamic polarization tests and salt spry tests. The research results show that a 4 μm thick oxide film grew rapidly on the surface of AZ80 magnesium alloy under the special prepared electrolyte and high density current. The corrosion resistance of ceramic coating prepared by the new technology was greatly improved for four order of magnitude and it was mainly consisted of dense layer, the coated samples exhibit excellent corrosion resistance not only in the potentiodynamic polarization tests but also in the long term corrosion tests.