The effects of 8-hydroxyquinoline on corrosion performance of a Mg-rich coating on AZ91D magnesium alloy

摘要

A Mg-HQ-rich primer was prepared by adding 45% pure magnesium particles and 5% 8-hydroxyquinoline in epoxy coating. The Mg-HQ-rich primer showed obviously better protection for AZ91D alloy than 50% Mg-rich primer. The additive 8-HQ combines with Mg~(2+) in the coating, forming a insoluble complex, MgQ_2, instead of Mg(OH)_2 on Mg particles. The MgQ_2 layer may retard dissolution of magnesium particles and prolong the cathodic protection effect of Mg-HQ-rich primer. Additionally, the corrosion products may also block the defects in the primer and the active sites on the substrate surface, thereby further increase the corrosion resistance of the Mg-HQ-rich primer.