Exploring the corrosion inhibition mechanism of 8-hydroxyquinoline for a PEO-coated magnesium alloy

In this study, the corrosion inhibition effect of 8-hydroxyquinoline (8HQ) on a PEO-coated AZ21 magnesium alloy is explored. The interaction of 8HQ molecules with both bare AZ21 and PEO layer was thoroughly scrutinized during the exposure to a corrosive NaCl electrolyte using different characterization methods, including EIS, SEM, Raman spectroscopy, and XRD. The corrosion inhibition mechanism stems from the extensive precipitation of the insoluble complex between 8HQ molecules and Mg2+ on top of the PEO layer, which leads to subsequently inhibition-enhancing phenomena, including modification of the corrosion products and re-precipitation of the PEO amorphous phase.