Enhanced Corrosion Protection of A-36 Steel Using Epoxy-Reinforced CSA-Doped Polyaniline-SnO2 Nanocomposite Smart Coatings

Abstract

Reinforced epoxy polymer nanocomposites have been employed as anti-corrosion coatings on various metallic substrates due to their beneficial characteristics and high electrochemical performances. In this work, we explore the anti-corrosion behavior of reinforced epoxy (EP) polymer nanocomposite consists of polyaniline (PANI)-tin oxide (SnO2) doped with camphor sulfonic acid (CSA). PANI-SnO2 nanocomposites doped with CSA were prepared by in situ chemical oxidative polymerization of aniline in the presence of SnO2 nanoparticles. The morphological and structural features of the prepared nanocomposites were investigated through scanning electron microcopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Further, the coatings of these PANI:SnO2 nanocomposites with epoxy were employed on A-36 steel (carbon steel) substrates to investigate their corrosion protection behavior. The effect of SnO2 presence in the composite towards enhancing the corrosion protection was discussed through the Tafel polarization, polarization resistance, and electrochemical impedance spectroscopy (EIS) as well as oxygen gas permeability studies. Successful formation of potential barriers and their corrosion inhibition abilities were discussed. The EP:PANI:SnO2 composite coatings demonstrate an excellent corrosion inhibition efficiency of 98% in comparison to neat epoxy (43%). The investigation on mechanical properties of these coatings indicates improved adhesion, Young’s modulus, and tensile strength due to the presence of SnO2 nanoparticles. Owing to their enhanced conductivity, superior electrochemical performance and excellent mechanical properties, these EP:PANI:SnO2 nanocomposite coatings could form smart anti-corrosion formulations in protecting A-36 steel against harsh environments.