Active deposition of bis (8-hydroxyquinoline) magnesium coating for enhanced corrosion resistance of AZ91D alloy

The growth mechanism and electrochemical behavior of bis (8-hydroxyquinoline) magnesium (Mg(HQ)2) coating on AZ91D alloy were studied by SEM, XRD and electrochemical techniques. The results show that the corrosion of AZ91D alloy in 8-hydroxyquinolate anion solution induces active deposition of flower-like Mg(HQ)2 coating on the alloy surface. The Mg(HQ)2 coating provides a long-term barrier by its self-healing behavior, retarding the corrosion attack of aggressive species. Once the coating suffers from corrosion defect, the released Mg2+ ions and 8-hydroxyquinoline anions tend to recrystallize on the defect in the form of Mg(HQ)2 deposits, thus effectively inhibits the further development of local corrosion.