Influence of Sodium Salts of Organic Acids as Additives on Localized Corrosion of Aluminum and Its Alloys

Abstract

Localized pitting is best described by a characteristic parameter called the pitting potential value (Ep). Although Ep is governed by a number of factors, including alloy composition, metallurgical history, and the corrosive environment, the strongest effect on Ep is produced by certain additives that differ from the aggressive anion and exert a beneficial effect. These are referred to as inhibitors. Potentiokinetic and potentiostatic anodic polarization curves were obtained on aluminum (Al) and Al alloys in mixed solutions containing sodium chloride with sodium benzoate, sodium acetate, or thioglycolic acid as inhibitors. Immersion time at the rest potential and corrosion products accumulated in the pits influenced the inhibition efficiency. Reliability of the polarization method was discussed.