Corrosion Performance and Preparation of Polyaniline Film on the Surface of AZ91 Magnesium Alloy

Abstract

Polyaniline (Pani) film was applied onto AZ91 magnesium alloy in aqueous solutions containing oxalic acid and aniline monomer by cyclic voltammetry (CV) technique, which then was characterized by means of IR and SEM technique. Furthermore, the corrosion performance of the coating was evaluated in 3.5%NaCl solution through examining the polarization curves, open circuit potential versus time and the electrochemical impedance spectroscopy (EIS). The results in- dicated that the Pani coating could effectively shift the free corrosion potential much positively for the coated AZ91 magnesium and led to significantly diminish its corrosion current density by two orders of magnitude. Long-term immersion experiments indicated that the Pani coating can effec- tively hinder the permeation of corrosive species toward matrix, thereby prevent AZ91 magnesium alloy from corrosion.