Incorporating GO in PI matrix to advance nanocomposite coating: An enhancing strategy to prevent corrosion

Abstract

This research endeavors to advance the anti-corrosive characteristics, mainly the physico-mechanical properties, by incorporating graphene oxide (GO) into a polyimide (PI) matrix. So, a nanocomposite coating is fabricated for an aluminum alloy substrate. Results reveal that the coating was uniformly dispersed across the surface signifying that the inclusion of GO increased the PI dispersion. The π–π stacking interactions between the aromatic rings of PI and GO contribute to their stability and improved anticorrosive properties. The incorporation of GO to PI films significantly enhances hydrophobicity, as evidenced by the increased contact angles. Assessing the corrosion resistance of the coating in a 3.5 wt% NaCl solution through electrochemical impedance spectroscopy and potentio-dynamic polarization establishes a prominent correlation between the percentage of GO and the anticorrosion efficiency of the composite coating. Precisely, the nanocomposite coating containing 5 wt% GO exhibits an impressive impedance modulus value of 107, and the corrosion current density (I cor) is drastically reduced by over three orders of magnitude, reaching 4.8 × 10−9 A cm−2, as indicated by the polarization curve. Also, prolonged immersion tests confirm the exceptional protective ability of the S5 coating (5 wt% GO), effectively shielding the metal for up to 100 h. After conducting diagnostic measurements, the hybrid nanocomposites of GO/PI examined in this study showcased their effectiveness as inhibitors in anticorrosive coatings. These composites played a vital role to hinder the oxidation of underlying aluminum alloy when exposed to oxidizing chemicals, water, or air, thereby extending the protective duration.

Keywords

• graphene oxide
• corrosion resistance
• composite coating
• active corrosion inhibition