Corrosion inhibition by Nafion®-polyaniline composite films deposited on stainless steel in a two-step process

The inhibition of pitting corrosion of stainless steel (SS) is addressed in this paper by using a new type of anticorrosive coatings consisting of Nafion®-polyaniline (PAn) composite films electrodeposited on stainless steel in a two-step process. The anticorrosive strategy presented here is based on the interfacial modification of SS with a Nafion® film, which as a cationic selective membrane prevents chloride ions to reach the SS surface. In addition, chloride insertion to the composite Nafion®-PAn film becomes less likely since sulfonate groups of the Nafion® contribute to the charge compensation of PAn and therefore charge transport processes involve proton expulsion than anion insertion. Nafion® films were pre-deposited at the surface of the SS electrode and the PAn films were formed on the SS|Nafion® electrode by cyclic voltammetry in 0.5 M H2SO4 solutions containing 0.1 M aniline. Open circuit potential and potentiodynamic measurements were used for the evaluation of the corrosion protection properties of the Nafion®-PAn composites.