Epoxy coating as effective anti-corrosive polymeric material for aluminum alloys: Formulation, electrochemical and computational approaches

In this work, a formulation based on epoxy coating composed of DGEBA cured with polyaminoamide has been used as anti-corrosive material for aluminum alloys (2024-T3, 5086 and 7075-T6) substrates for accelerated corrosion assays. The epoxy coating on aluminum alloys samples was tested in 3.0 wt% NaCl solution using salt spray test chamber. The anticorrosive behavior of the aluminum alloys samples under these conditions was monitored by impedance diagrams Bode and Nyquist plots and theoretical studies by DFT, MC and MD. The results showed that the evolution of the impedance modulus plots vertical bar Z vertical bar(0.01) (Hz) values of the epoxy coating applied on AA2024-T3, AA5086 and 7075-T6 samples began from 2.63, 1.46 and 0.43 M Omega.cm(2) after 1 h of immersion and finally reached 0.27, 0.26 and 0.24 M Omega.cm(2) after 4392 h of immersion, respectively. The lessening of impedance with submersion time means that the electrolyte scatters into the epoxy coating and diminishes the boundary properties of the film. DFT calculations were used to determine the coatings adsorption centers. Additionally, the Monte Carlo and Molecular Dynamics calculations support the coatings strong adsorption interaction with the metal surface, providing molecular evidence for the epoxy molecule's adsorption behavior (geometry) and adsorption energy on the aluminum surface. Theoretical results (DFT, MC, and MD) corroborate the experimental results. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, an epoxy coating was used as an anti-corrosive material for aluminum alloys. The corrosion behavior of the aluminum alloys samples was tested and theoretically studied. The results showed a decrease in impedance over time, indicating electrolyte penetration into the coating and a reduction in film properties. Theoretical calculations supported the experimental results.