Anticorrosion mechanism of FACs-GO hybrids in ER coatings by EIS and MD simulation

Abstract

To explore the enhancement of corrosion resistance and the microscale anti-corrosion mechanism of the epoxy resin (ER) composite coatings, this study prepared ER composite coatings using fly ash microbeads (FACs) and graphene oxide (GO) as fillers, conducted immersion corrosion experiments, and characterized the corrosion resistance of the coatings using electrochemical impedance spectroscopy (EIS). The experimental results showed that the FACs-GO/ER composite coating immersed for 7 days exhibited an impedance modulus three orders of magnitude higher than that of the pure ER coating. Furthermore, molecular dynamics (MD) simulations were carried out to calculate the interaction energy between ER matrix and fillers, free volume, and water molecule diffusion coefficient. It is revealed by MD simulations that the FACs-GO hybrid filler combined the performance advantages of both FACs and GO fillers, significantly improving dispersibility and compatibility within the ER matrix. The hybrid/ER composite material exhibited the lowest free volume, indicating enhanced densification of the ER material. The diffusion coefficient of water molecules in the FACs-GO/ER composite MD model decreased, indicating that the hybrid filler effectively enhanced the barrier properties of the ER composite coating against corrosive media. Therefore, the excellent dispersibility and shielding adsorption of FACs-GO hybrid fillers improved the corrosion resistance of the coating and revealed the microscale corrosion resistance mechanism of FACs-GO hybrid fillers in ER coatings.