Synergic enhancement of the anticorrosion properties of an epoxy coating by compositing with both graphene and halloysite nanotubes

Abstract

The aim of this research was to improve the corrosion resistance of metal surfaces with polymer coatings. Both graphene and halloysite nanotubes (HNTs) were introduced together into the epoxy resin coating for the enhanced barrier protection of the metallic surface. The anticorrosion behaviors of different coatings were comparatively evaluated by the potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), and neutral salt spray (NSS) tests. The potentiodynamic polarization curves showed that the coating containing 0.5 wt % HNTs and 0.8 wt % graphene (H05G08EP) together had the most positive corrosion potential and the minimum corrosion current density. The EIS results revealed that graphene endowed the composite coatings with excellent electrochemical performance for anticorrosive purposes. The NSS tests indicated that H05G08EP endured the longest NSS time. These results suggest that H05G08EP had the best corrosion resistance.

Preparation and properties of thermosetting powder/graphene oxide coatings for anticorrosion application

“…Q is the constant phase element, which deviates from the ideal capacitance, Q c relates to the capacitance at the electrolyte‐coating interface, and Q dl is related to the capacity of the electric double layer at the electrolyte–substrate interface. As shown in Figure (a,b), Warburg component ( Z w ) was present at both two circuits, indicating the occurrence of diffusion‐controlled corrosive reactions at the electrolyte–metal interface, resulting from the severe metal corrosion of TP and TP@GO 10 . However, the R ct of TP@GO 10 (8.4 × 10 3 Ω cm 2 ) was larger than TP (1.0 × 10 3 Ω cm 2 ), confirming improved corrosion resistance of TP@GO 10 .…”

“…However, use of high volatile organic compound solvent systems can lead to environmental contamination, so there is an interest in the development of water‐based organic coatings. Waterborne epoxy resin/graphene coatings were prepared with excellent anticorrosion properties and without organic solvents . However, the use of water as a solvent can increase corrosivity for metals, has high solubility for O 2 , and requires a lengthy drying process.…”

Preparation of transparent nanocomposites from UV‐ and thermo‐curable epoxyacrylate and graphene oxide for the application of corrosion protection coatings

“…All the EA/GO‐coated samples exhibited two semicircles in the Nyquist plots, which matched the second equivalent circuit with two time constants. The first semicircle at a high frequency was fitted into the model having a parallel arrangement of R coat and CPE coat ; the second semicircle at a low frequency was caused by the corrosion cell ( R ct − CPE dl ) formed at the coating–substrate interface with electrochemical reaction, where R coat and R ct represent the coating resistance and the resistance of charge transfer, respectively, CPE coat and CPE dl representing the constant phase elements (CPE) of the coating and double layer between the coating and steel plate, respectively . The impedance elements were thus estimated from the models, and the results for samples being pre‐immersed in salt solution for 72 h are summarized in Table (data for immersion times of 24 and 48 h are not shown here).…”

Synthesis of graphene oxide functionalized by phytic acid for anticorrosive reinforcement of waterborne epoxy coating

“…However, graphene sheets are easily agglomerated due to π-π stacking which makes it hard to disperse uniformly in the resin to form a physical barrier. To solve this problem, many dispersants, like polydopamine, 26 tannic acid, 27 polyethyleneimine, 28 tetraethoxysilane, 29 lignin 30 and inorganic particles such as halloysite nanotubes, 31 nano-TiO 2 , 32 Fe 3 O 4 , 33 have been developed to improve the dispersibility of graphene in WEP coatings for enhancing anticorrosion performance in the last few years. For example, Cui et al 26 modified graphene with polydopamine and obtained the GO-PDA nanosheets which can be well-dispersed in waterborne epoxy resin.…”