Enhanced the Electrochemical Stability of Al-Zn-Mg Alloy through the Dual Incorporation of ZrO2 and V2O5 into the Alumina Layer

Abstract

This study explores the impact of direct and indirect incorporation of metallic oxide particles namely ZrO2 and V2O5 on the corrosion behavior of the alumina layer obtained by the plasma electrolytic oxidation of Al-Zn-Mg alloy. To achieve this goal, plasma electrolytic oxidation coating was formed in an alkaline-aluminate-ZrO2 electrolyte, without and with NH4VO3. The morphological analysis reveals a porous structure influenced by gas bubble discharge and rapid cooling, featuring micro-pores, oxide nodules, and cracks. The incorporation of V2O5 particles is observed to decrease surface roughness and enhance the compactness of the oxide layer. The X-ray diffraction patterns reveal the presence of γ-Al2O3, α-Al2O3, ZrO2, and V2O5 particles exclusively in the sample coated in the electrolyte with NH4VO3. Potentiodynamic polarization tests in a 3.5 wt.% NaCl solution revealed enhanced corrosion resistance, attributed to reduced micro-defects through V2O5 and ZrO2 incorporation.