Cailiao Baohu (Jul 2023)
Effect of Nano-BN Particles on Microstructure and Wear Resistance of Micro-Arc Oxidation Coating on 7075 Aluminum Alloy
Abstract
In order to improve the wear resistance of 7075 aluminum alloy surface，the hard ceramic coating on the aluminum alloy surface was constructed by micro-arc oxidation technology in the electrolyte solution doped with nano-BN particles.The effects of the addition of nano-BN particles on the arc initiation voltage of the micro-arc oxidation process，surface morphology，porosity，phase composition，thickness，roughness，microhardness and friction and wear properties of coating were investigated by means of scanning electron microscopy (SEM)，energy dispersive spectrometer (EDS)，X-ray diffractometer (XRD)，photoelectron spectrometer (XPS)，roughness tester，microhardness tester，friction and wear testing machine.Results showed that the coatings were mainly composed of α-Al2O3 and γ-Al2O3 phase.Nano-BN particles increased the arc initiation voltage，and increased the thickness，roughness and hardness of coating.When the concentration of nano-BN particles was 0.3 g/L，the overall performance of the as-obtained micro-arc oxidation coating was the best.At this time，the number of micropores in the coating was small，the pore size was small，and the surface density was high.Compared with the coating prepared in the basic electrolyte，the coating’s surface porosity decreased from 6.617%to 3.518%.Meanwhile，the hardness reached the highest value 916.7 HV10 N，the thickness was 20 μm，and the roughness was 2.38 μm.The friction coefficient was reduced to 0.7，and the wear rate decreased to 7.84×10-5 mm3/(N·m).
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