Abstract: The surfaces of 2524 Al-alloy,an advanced door & window frame-material,were modified with Al₂O₃-coatings synthesized by micro-arc oxidation(MAO).The influence of the Al₂O₃ powder,added into the electrolyte,on the microstructures and tribological properties was investigated with X-ray diffraction,scanning electron microscopy,energy dispersive spectroscopy and conventional mechanical probes.The results show that the addition of Al₂O₃ powder significantly improved the quality of MAO Al₂O₃ coatings.To be specific,the smoother and more compact MAO Al₂O₃ coatings,comprising more α-and γ-phased Al₂O₃ grains,and lower density of pores and micro-cracks.The MAO Al₂O₃ coatings,31.2μm in thickness,have a hardness of 510 HV,a stronger wear-resistance and a lower average friction coefficient(0.45).Possible mechanisms responsible for the quality improvement of MAO coatings,grown in Al₂O₃-powder added electrolyte,were also tentatively discussed in a thought provoking way.