Inhibition of corrosion on AA2024-T3 by rare earths & mercaptoacetate

The use of the aluminium alloy AA2024-T3 has long been associated with a strong vulnerability to localised corrosion. Dealloying and pitting corrosion can occur on and around intermetallic particles when exposed to aggressive environments such as sodium chloride electrolytes. Specific combinations of rare earths and organic compounds have demonstrated strong synergistic inhibition on the AA2024-T3 alloy. This work has focused on rare earths and organic compounds containing thiol functional groups. It is believed that the sulphur in the thiol group can form protective films over the surface of copper-rich intermetallic particles due to the affinity between copper and sulphur. Previous studies with the multiwell tests have identified that solutions containing sodium mercaptoacetate provided strong inhibition at pH 3 and 6. This work presents the initial findings from the polarisation tests and constant immersion corrosion experiments in the presence of sodium mercaptoacetate.