Characterization of miro-arc oxidation coatings on cast aluminum alloy doped with different Y2O3 particle concentration

Abstract

Different micro-arc oxidation coatings were fabricated on cast aluminum alloy substrates in the electrolytes with Y2O3 particles addition varying from 0 to 4.0 wt% (0, 1.0, 2.0, 3.0, 4.0 wt%). The effect of Y2O3 particle concentration on microstructure, phase composition and corrosion resistance of coatings was respectively characterized by Scanning Electron Microscope (SEM), x-ray Diffraction (XRD) and Electrochemical Workstation. The surface morphologies of the coatings indicated that the coating formed in the electrolyte with 4.0 wt% Y2O3 particles had the most compact and uniform structure with the smallest micro-pores. Polarization curves results indicated that the specimen coated in the electrolyte with 4.0 wt% Y2O3 had the lowest corrosion current density and corrosion rate, accordingly, the best corrosion resistance. The phase composition of the coatings consisted of α-Al2O3, γ-Al2O3, Y2O3, SiO2 and AlPO4, which proved that Y2O3 particles were involved in the formation of MAO coatings and were beneficial to the improvement of coating performance.