Influence of complex SiF62-Ions on the PEO coatings formed on Mg-Al6-Zn1 alloy for enhanced wear and corrosion protection

Abstract

The present study was carried out to explore the effect of SiF62- incorporation and concentration on the plasma electrolytic oxidation (PEO) coatings formed onAZ61Mg alloy. The coatings were prepared using electrolyte solution with various concentration of Na2SiF6 (0.0-0.7 g/L). Highly compact coatings with minimum porosity were obtained for an optimum concentration of Na2SiF6 ~0.3 g/L added into the electrolyte. The highest corrosion resistance, ~2.04 × 105 W•cm2, was obtained for 0.3 g/L of Na2SiF6, in addition to its superior anti-wear properties. However, it was found from the scanning electron microscope (SEM) image analysis that increasing concentration above 0.3 g/L, could cause severe breakdown in the inner layers, and thus the said coatings could not withstand effectively against wear and corrosion.