A recent report described the effect of graphene on the corrosion of zinc particles in waterborne epoxy zinc-containing coatings.  In the study, graphene/ waterborne epoxy zinc-containing coatings with different graphene contents were prepared, and their corrosion resistance properties were investigated by electrochemical impedance spectroscopy (EIS), immersion testing and neutral salt spray.

The results showed that addition of 0.6 wt% graphene into the coating could remarkably improve its cathodic protection and barrier performance compared to the coating without graphene.

In addition, the effects of graphene on the corrosion evolution of zinc particles in the coating were studied by the field-emission scanning electron microscopy (FE-SEM) coupled with energy dispersive spectroscopy (EDS), which showed that the zinc particles near the interface between a steel substrate and the coating corroded first after the corrosive media diffused into the coating.  The zinc particles then continued to be corroded from the interface to upper part of the coating as they provided cathodic protection to the substrate due to the electrical connection of graphene.  X-ray diffraction (XRD) patterns confirmed the corrosion products of the zinc particles were mainly consisted of Zn5(OH)8Cl2.H2O.

The study was published in Progress in Organic Coatings, Volume 140, March 2020.