The diffusion-dynamical and electrochemical effect mechanism of oriented magnetic graphene on zinc-rich coatings and the electrodynamics and quantum mechanics mechanism of electron conduction in graphene zinc-rich coatings

Magnetic graphene was prepared by modified polyol methods. Gallic acid-based epoxy resin was synthesized and adopted to enhance the dispersion of graphene. Four kinds of coating were prepared, and they were graphene coatings (G), magnetic graphene coatings (MG), magnetic graphene coatings oriented by magnetic field (MG-MF), magnetic graphene zinc-rich coatings (MG/Zn), magnetic graphene zinc-rich coatings oriented by magnetic field (MG/Zn-MF). Magnetic graphene has a larger size than the graphene, which reduced its delamination in the coatings and weakened the protective ability. After the oriented treatment by magnetic field, the parallel hierarchical arrangement of magnetic graphene significantly increased the diffusion resistance of corrosive medium and improved the corrosion resistance of the coatings. The diffusion kinetics of corrosive media in the coatings was established. However, the orientation of magnetic graphene attenuated the cathodic protection of zinc-rich coatings, due to the reduction of effective electron transport path and active interfacial zinc. The electrons lost by the anode sacrifice of zinc needed to cross two types of potential barriers in the process of migrating to the protected metal. They were metal-graphene potential barrier and graphene-graphene potential barrier. According to the calculation and modeling of electrodynamics and quantum mechanics, electron penetration through the latter barrier was less difficult than the former and graphene facilitated the transfer of electrons between metals. This was also the microscopic mechanism of graphene improving the cathodic protection of zinc-rich coatings. (C) 2019 Elsevier B.V. All rights reserved.