The effect of polycrystalline graphene on corrosion protection performance of solvent based epoxy coatings: Experimental and DFT studies

In this research, the effect of polycrystalline graphene (PG) on corrosion protection performance of epoxy coating is investigated. Various quantitative and qualitative characterization techniques of X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Porosimety were employed for characterizing the sample and studying the structure of morphology of the PG. Furthermore, the field emission scanning electron microscopy was considered for investigating the PG dispersion in coating. The corrosion protection performance of epoxy coatings containing different wt.% of PG (0.05, 0.1, 0.3, and 0.5) is evaluated by electrochemical impedance spectroscopy. The results obtained using the prepared nanocomposite showed that the nanocomposite coatings provided higher corrosion resistance compared with the pure epoxy. Meanwhile, nanocomposites containing 0.05 wt% PG show superior corrosion resistance and lower wettability (∼12% decrease in water contact angle). The PG sheets agglomerate in matrix by increasing the loading of PG, leading to increase of hydrophilicity and decrease of corrosion protection. Also, the quantum chemical calculations and Density Functional Theory are performed which confirmed the better performance of the epoxy/PG nanocomposite compared with pure samples.