Inhibition of Pitting Corrosion of AISI 304L Stainless Steel by Surface Active Compounds

A series of compounds having the N-acylamino acid or related structure were investigated as potential inhibitors of localized corrosion of AISI(1) 304L stainless steel (SS). The effect of these compounds on the breakdown potential was measured using the linear current scan method. Interaction of the inhibitors with the electrode surface was studied using capacitance measurements and correlated with solution surface tension measurements. Successful inhibitors interact strongly with the AISI 304L SS surface, but the inhibition effect appears to involve more than just adsorption of the inhibitor. Evidence is presented for the formation of a hemimicellar inhibitor layer, which could exclude chloride ions from the surface or provide surface pH buffering. Formation of such a layer is sensitive to the structure of the compound.