Cerium- and phosphate-based sealing treatments of PEO coated AZ31 Mg alloy

This study investigated cerium- and phosphate-based sealing treatments of PEO coated AZ31 Mg alloy samples in view of their characteristics and corrosion resistance in 0.5 M NaCl solution. Potentiodynamic polarization experiments and immersion tests in NaCl solution showed that corrosion resistance of PEO coated AZ31 was increased by the sealing treatment in cerium or phosphate solution. The combination of two sealing treatments, first in the cerium and second in the phosphate solution, was found to significantly increase the corrosion resistance of PEO coated AZ31. The best corrosion resistance was obtained for a sample with sealing treatment for 20 min in the cerium followed by 20 min in the phosphate solution.