Surface Modification of 2524 Al-Alloy with Al2O3 Coatings Synthesized by Micro Arc Oxidation
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Graphical Abstract
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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.
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