Characterization of Zn-Ni-Al₂O₃ electrophosphate nanocomposite coating for enhanced corrosion resistance

In this study, the Zn-Ni-Al 2 O 3 phosphate nanocomposite coatings were deposited via cathodic electrochemical method at different concentrations of alumina nanoparticles. The morphology and chemical composition of the coatings were studied by scanning electron microscope (SEM) and EDS analysis. Also, the corrosion resistance was studied through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests. The results indicated that by increasing the nanoparticles in the coating, the porosity of coatings is decreased, which is due to alumina incorporation in the porosity and acting as nucleation sites. Results of corrosion studies reveal that the corrosion current density is decreased from 10 μ A cm −2 to 1.023 μ A cm −2 by incorporating the alumina nanoparticles in the coating. Moreover, the EIS results indicated that the corrosion proceeds via charge transfer mechanism.