Smart self-healing anti-corrosion vanadia coating for magnesium alloys

Eco-friendly vanadia based chemical conversion coating was applied for improving the corrosion resistance of a newly developed magnesium AZ31 HP–O alloy. The effect of vanadia solution concentrations (10, 30 and 50 g/l) and pH (neutral pH 7 and pH 9) on the corrosion protection performance of a magnesium substrate were investigated. EIS and linear polarization techniques were used to evaluate the electrochemical behavior in 3.5% NaCl. The results showed a marked increase in the localized corrosion resistance after applying vanadia surface treatment of 50 g/l due to self-healing effect. The optimum conditions to obtain protective coatings for AZ31 HP–O with a self-healing ability were determined. Changes in surface morphology, composition and microstructure of the conversion coatings were followed by SEM-EDS and macroscopic imaging techniques.

► Newly developed one-step eco-friendly vanadia conversion coating was used for improving the corrosion resistance of magnesium alloys prior to applying a top paint. ► The proposed route is very simple and based on free immersion of magnesium substrate in a vanadia solution of 50 g/l concentration. ► The coating formed due to such route is characterized by a self healing ability.