Anti-corrosion performance of PANI and POEA coatings applied into 13% Cr stainless steel at 3.5% NaCl solution with neutral pH

The doped PANI and POEA polymers were incorporated into a commercial epoxy resin with xylene solvent to develop effective anticorrosion coatings applied to 13% Cr stainless steel. The produced epoxy resin coatings were systematically characterized by FTIR, XRD, SEM, AFM, and immersion tests. The corrosion resistance performance of the ZP, PANI, and POEA coatings was evaluated through potentiodynamic polarization, electrical impedance spectroscopy, open circuit potential (OCP), and linear polarization resistance (LPR) measurements in a long-term exposure to a 3.5% NaCl solution at pH 6.5. The corrosion resistance of the commercial ZP coating was significantly improved by the PANI and POEA coatings, and their performance was correlated with the highly enhanced protection of the passivation barrier provided. The higher corrosion resistance observed in POEA coatings in acidic ambient conditions is explained by the auxiliary cathodic reaction between the conducting emeraldine PANI and the nonconducting leuco-PANI. The suggested manufacturing method for storage tanks can be used to simultaneously replace the substrate (carbon steel) and the conventional anticorrosion coating based on zinc phosphate.