Preparation of Anticorrosive Epoxy Nanocomposite Coating Modified by Polyethyleneimine Nano-Alumina

Abstract

Aluminum alloys with low density and high specific strength have been widely used in marine engineering. Epoxy coatings, a simple and economical protection strategy, have been applied on alloy surfaces to prolong service life. However, a pure epoxy coating cannot provide long-term protection for metals in the marine environment. Hence, in this work, nano-alumina (nano-Al2O3) modified by polyethyleneimine (PEI) were added into epoxy coatings to enhance anticorrosion properties. Using Fourier transform infrared spectroscopy (FTIR), we found that the molecular chain of PEI was successfully grafted on the surface of nano-Al2O3, and the cross profile of coatings indicated that the modified nano-Al2O3 uniformly dispersed in the epoxy coating. Electrochemical impedance spectroscopy (EIS) results demonstrate that the coating resistance of the modified epoxy nanocomposite coating was 10 times higher than that of the pure epoxy coating after 3 days of immersion in 3.5 wt.% NaCl solution. Meanwhile, the surface morphologies and EDS-mapping of substrates after EIS testing show that the substrate coated with modified epoxy nanocomposite coating had the smallest amount of corrosion products. These results show that this modified epoxy nanocomposite coating has excellent anticorrosion performance.