Anti-corrosion mechanism of 2D nanosheet materials in waterborne epoxy coatings

Nowadays, 2D nanosheet materials play a crucial role in enhancing the corrosion resistance ability of organic coatings. In this work, three kinds of 2D nanosheet materials with different conductivity including graphene (G), graphene oxide (GO) and hexagonal boron nitride (H-BN) were specially chosen and functionalized by 3-aminopropyltriethoxysilane (APTES). Then, a series of waterborne epoxy composite coatings were fabricated by incorporation of functionalized graphene (FG), graphene oxide (FGO) and hexagonal boron nitride (FH-BN). The microstructure and morphology feature of FG, FGO and FH-BN were characterized by Fourier transform infrared spectroscopy, x-ray diffraction, scanning electron microscopy and transmission electron microscopy. The corrosion resistance of composite coatings was obtained by Tafel analysis and electrochemical impedance spectroscopy measurements by being immersed in a 3.5 wt% NaCl aqueous solution for different periods. It turns out that the composite coating with FH-BN additive exhibited the best anticorrosive ability among all samples. The analysis of corrosion products on the Q235 surface suggest that the anticorrosive performance of 2D materials reinforced epoxy composites coatings were not only dependent on the barrier properties but also was affected by the properties of the 2D nanosheet materials. In addition, the distinct anti-corrosion mechanisms of 2D nanosheet materials incorporated with waterborne epoxy were tentatively discussed.