Surface Modification of AZ80 Mg-Alloy with ZrO₂ Coatings

The ZrO₂ coatings were synthesized in two steps: first,Zr-coatings were deposited by unbalanced magnetron sputtering on substrate of AZ80 Mg-alloy; second,the Zr-coatings were micro-arc oxidized(MAO).The influence of the MAO technique on the microstructures and tribological properties of the surface modified AZ80 Mg-alloy,an advanced material for automobile fabrication,were characterized with X-ray diffraction,energy dispersive spectroscopy,scanning electron microscopy and conventional mechanical tools.The results show that micro-arc oxidation makes the difference.To be specific,the Zr-layer was completely oxidized; and the smooth compact ZrO₂ coatings,5 μm in thickness,comprised the dominance of cubic ZrO₂ grains and randomly distributed MgO and Mg particles.The ZrO₂ coatings with fairly strong interfacial adhesion significantly improved the hardness and wear-resistance of AZ80 Mg-alloy.