Synergistic effect of ultrasound-assisted and ZrO2 nanoparticle sealing on microstructure and mechanical properties of aluminum alloy micro-arc oxidation coating

The coating prepared by the conventional micro-arc oxidation (MAO) process usually has a porous structure, which cannot effectively block the invasion of corrosive media, thus reducing corrosion resistance and wear resistance. In this study, composite oxide coatings were prepared on 6061 aluminum alloy by using ultrasound-assisted MAO technology and adding ZrO₂ nanoparticles in phosphate solution. The microstructure and elemental composition of the coating were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), and the wear resistance and corrosion resistance were tested. The results show that under the synergistic effect of ultrasonic assistance and nanoparticle sealing, the porosity of the composite coating is reduced from 6.35 % of the traditional MAO coating to 2.85 %, the corrosion current density is three orders of magnitude lower than that of the substrate, and it has excellent wear resistance and density. These properties effectively improve the service life of the metal.