Excellent anti-corrosion performance of epoxy composite coatings filled with novel N-doped carbon nanodots

Abstract

Nanofillers play an important role in the field of anticorrosion. This paper focuses on the study of the anticorrosion performance of a novel N-doped carbon nanodots(CNDs) in epoxy coating. N-doped carbon nanodots(CNDs) with a size of about 100 nm is synthesized by hydrothermal method using citric acid as carbon source. The chemical structure and morphology of CNDs are studied by Fourier transform infrared spectroscopy(FT-IR), ultraviolet spectrophotometer(UV–vis), X-ray photoelectron spectroscopy(XPS), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The water absorption of the coating is studied by gravimetric method. The corrosion resistance of the coating is analyzed by electrochemical impedance spectroscopy(EIS). The results reveal that the corrosion resistance of epoxy coating is significantly improved by adding the appropriate amount of CNDs, as it can effectively reduce the porosity of the coating and extend the path of corrosive medium penetrating the coating, thus enhancing the corrosion resistance of the coating. After soaking in 3.5 wt% NaCl solution for 480 h, the low frequency impedance of the 0.15 wt% CNDs/epoxy nanocomposite coating is 1.85x1010 ohm·cm2, which is greatly improved compared with that of the pure epoxy coating (5.43 × 104 O·cm2). The water absorption result shows that the water absorption of the coating with CNDs content of 0.15 wt% is much lower than that of the pure epoxy coating. The corrosion resistance is greatly improved.