Abstract
In this paper, graphene oxide (GO) was grafted with sodium tripolyphosphate (STP) to achieve a new anti-corrosive pigment (STG) with homogenous dispersion in waterborne epoxy (EP). The results obtained from Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and X-ray Diffraction (XRD) revealed that STP was successfully combined with GO by chemical bonding. The corrosion resistance of EP, GO/EP and STG/EP coatings on carbon steel substrates was investigated via electrochemical impedance spectroscopy (EIS) and salt spray test. The EIS results showed that the impedance value of coating with 0.7 wt.% STG reached 1.019 × 109 Ω∙cm2, which was considerably higher than that of neat waterborne EP coatings. Salt spray test results revealed once again that STG (0.7 wt.%)/EP coating had superior corrosion resistance. Besides, the STG (0.7 wt.%)/EP coated sample showed the highest adhesion strength between coating and substrate.
Highlights
The waterborne epoxy resin, a kind of thermosetting resin which has exceptional adhesion, anti-corrosion properties and characteristics of environmental friendliness, is frequently used in organic anti-corrosive coating [1,2]
GO and STP were combined by chemical bonding to achieve a new kind of anti-corrosive pigment—graphene oxide grafted with sodium tripolyphosphate (STG)
The results proved that STG was successfully synthesized characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD)
Summary
The waterborne epoxy resin, a kind of thermosetting resin which has exceptional adhesion, anti-corrosion properties and characteristics of environmental friendliness, is frequently used in organic anti-corrosive coating [1,2]. One of the effective methods for improving the corrosion resistance of the waterborne epoxy coating is adding nano pigments, such as mesoporous materials [3,4,5,6,7,8], layered materials [9,10,11], metal-organic frameworks [12,13] and so on. ZSM-5 [14], mesoporous-TiO2 [15,16], layered double hydroxides and metal-organic frameworks [17] have been investigated as anti-corrosive pigments. The results showed that porous and layered structure can improve the corrosion resistance of coatings via blocking or prolonging the erosion path of corrosive media, which was called the labyrinth effect. A promising two-dimensional (2D) carbon material, with excellent chemical stability and high barrier property, has been extensively applied in the field of epoxy anti-corrosive coating [18,19]
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