Corrosion behavior of ZnNiAl2O3 nanocomposite coatings obtained by electrodeposition from alkaline electrolytes

Abstract

AbstractThe aim of this work was to investigate the anti‐corrosive properties of nanocomposite ZnNi coatings containing Al2O3 nanoparticles, prepared from alkaline commercial electrolytes (pH 13), (PERFORMA 280.5, COVENTYA S.A.S, France), by electrodeposition on carbon steel (OL37). The corrosion resistance of the coatings prepared with different concentrations of Al2O3 (5, 10, and 15 g/L) was evaluated in 0.2 g/L Na2SO4 solution (pH 5) by open circuit potential (OCP) measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques. The results of electrochemical measurements were corroborated with those obtained by using X‐ray diffraction analysis. The obtained results show that the introduction of Al2O3 nanoparticles in the plating bath generally brings an increase in corrosion resistance of ZnNi layers and put in evidence the existence of an optimal Al2O3 concentration. Under the examined conditions, the optimal concentration determined from polarization measurements was proven to be 5 g/L Al2O3. The highest value of the polarization resistance, Rp, obtained from impedance measurements corresponds also to ZnNi with 5 g/L Al2O3, which is in agreement with the results obtained from polarization and XRD measurements.