Innovative application of electro-polymerized polyaniline for enhanced corrosion protection of aluminum alloys in chloride environments

Abstract

Aluminum's lightweight nature and versatility have established it as a key material in multiple industries, yet its inherent susceptibility to corrosion limits its broader application. This study investigates the electro-polymerization of polyaniline (PANI) on aluminum alloy surfaces through cyclic voltammetry in an aqueous solution of sulfuric acid, oxalic acid, and aniline. The corrosion performance of the resulting PANI coatings was evaluated in a NaCl environment using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Results showed a marked decrease in corrosion current density from 2121.27 mA/cm 2 for the uncoated sample to 622.2 mA/cm 2 for the PANI-coated alloy. Moreover, the corrosion potential shifted positively from −817.7 mV/SCE to −739 mV/SCE, underscoring the protective effect of the polyaniline film. Fourier-transform infrared spectroscopy (FTIR) confirmed the stable formation of PANI, characterized by distinct benzenoid and quinoid structures, while UV–visible spectroscopy revealed characteristic polaronic absorption bands indicative of the polymer's conductive emeraldine state. Surface morphology and composition were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD), confirming the uniform coverage and integrity of the PANI coating. These findings highlight the promising role of electro-polymerized polyaniline in significantly enhancing the corrosion resistance of aluminum alloys, particularly in chloride-rich environments.