Polyethyleneimine as a corrosion inhibitor for ASTM 420 stainless steel in near-neutral saline media

The effect of polyethyleneimine (PEI) as a corrosion inhibitor for ASTM 420 stainless steel in 3% aqueous NaCl solution was studied. The results of linear polarization and cyclic polarization measurements indicate high inhibiting effectiveness of the selected organics. Moreover, from cyclic polarization measurements it can be deduced that PEI acts as an inhibitor against pitting corrosion. Immersion tests in the presence of PEI showed remarkable corrosion protection against uniform corrosion. Film persistency immersion testing indicated that once the protective layer is formed, it is very stable in a non-inhibited NaCl solution. X-ray photoelectron spectroscopy measurements showed that PEI binding is mediated by electrostatic interactions between PEI and the substrate. A dense layer of PEI might be effective either in preventing diffusion of ionic species from the film or in preventing attack by chlorine from the salt water.