Wear Resistance of Micro-arc Oxidized Ceramic Layers on Aluminum alloy

The structure and property aspects of oxide films formed on 7075 aluminum alloys by micro-arc oxidation in alkali-silicate electrolytic solution was discussed.Microstructure,surface morphology and phase composition of the ceramic coatings were investigated by SEM and XRD.Distribution of hardness along the coating thickness was determined by micro-hardness analyses.The friction and wear behavior of the oxide films against steel counterparts was evaluated with a friction and wear tester.The results show that the micro-arc oxidation coatings composed mainly of α-Al2O3 and γ-Al2O3 phase are dense and uniform,which indicates that the wear resistance of Al alloy could be improved obviously by micro-arc oxidation.The films possess a beneficial combination of 25~45μm thickness,HV0.11900 micro-hardness and provide a low wear rate but a relatively high friction coefficient against GCr15 steel under dry friction condition.