Adverse effect of 2,5PDC corrosion inhibitor on PEO coated magnesium


Besides their noteworthy tribological and corrosion protection properties, Plasma Electrolytic Oxidation (PEO) coatings feature a porous microstructure that is able to host corrosion inhibitors. This study reveals that although 2,5pyridindicarboxylate (2,5PDC) shows a remarkable corrosion inhibition effect for bare AZ21 Mg alloy, it can extensively deteriorate a PEO coating on the same Mg substrate, resulting in an overall accelerated failure of the PEO-coated AZ21 alloy. The deteriorative behavior of 2,5PDC towards PEO-coated AZ21 is explained based on the characterization of the bare and PEO-coated AZ21 exposed to the NaCl electrolyte with and without inhibitor using EIS, SEM, STEM and ToF-SIMS.
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