Abstract
Abstract This study reports a facile method to prepare silica-coated graphene oxide nanoflakes (SiO2–GO). Results of X-ray diffraction analysis, Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and atomic force microscopy reveal that silica was successfully coated on the GO flakes. The effect of SiO2–GO nanosheets on the corrosion protection and barrier performance of the epoxy coating was investigated in this work. Results indicate that the mechanical properties of all coatings added with GO and SiO2–GO were significantly improved. Furthermore, electrochemical impedance and Tafer polarisation curves showed that added 0.5 wt% SiO2–GO nanoflakes into zinc-rich epoxy coating could greatly improve the anti-corrosion performance of the sample, and the corrosion protection efficiency increased from 67.01 to 99.58%.
Highlights
Organic coatings play an important role in physical barriers and inhibitors between metal surfaces and corrosive media
2.5.3 Electrochemical performance test: The anti-corrosion performance of the Graphene oxide (GO)/zinc-rich epoxy (Zn-EP) and SiO2–GO/Zn-EP coatings was measured by corrosion weight loss, electrochemical impedance spectroscopy (EIS) and the Tafel polarisation test
The SiO2–GO fillers could efficiently decrease the number of holes on the coating surface and to increase the barrier performance, this could be demonstrated by the contact angle (CA) increased from 56.8° to 85.1°
Summary
Organic coatings play an important role in physical barriers and inhibitors between metal surfaces and corrosive media. They can greatly reduce the corrosion rate of metal surfaces and have been widely applied for anti-corrosion protection (Arman et al 2013; Jalili et al 2015; Ramezanzadeh et al 2015, 2016a,b,c) These organic coatings did not provide universal corrosion protection, with some corrosive substances still able to breach the surface of the coating through different corrosion paths (Maksimovic and Miskovic-Stankovic 1992), resulting in accelerated corrosion of the coating surface and the formation of pores and defects (Alam et al 2013; Liu et al 2009), thereby decreasing barrier performance. The conductivity of zinc and iron principally relies on the contact of vast zinc powder in the coatings and zinc formed zinc oxide and others formed some corrosion products during the process of anode protecting cathode, greatly impeding zincrich epoxy coatings’ development (Chavrier et al 1988) It can provide some barrier effect, the coating is
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