A mechanistic study of the enhanced cathodic protection performance of graphene-reinforced zinc rich nanocomposite coating for corrosion protection of carbon steel substrate

The impact mechanism of graphene nanosheets on the corrosion resistance and protection performance of zinc rich epoxy coatings was investigated. The potential-time measurement, electrochemical impedance spectroscopy (EIS), salt spray fog testing and scanning electron microscopy were used to characterize the protection performance of coatings. A relatively simple EIS model was used to characterize the effect of graphene nanosheets in terms of percolating structure of the zinc rich epoxy coating. The results of corrosion studies revealed that while addition of 0.4 wt% of graphene nanosheets resulted in potent protection performance of zinc rich coating, a low amount of graphene content exhibited a reverse effect. It was concluded that the enhancement of the corrosion protection performance of the ZRE coating in presence of a satisfactory loading of graphene particles could be attributed to the more uniform activation of zinc particles and also the superior percolation action of graphene nanosheets. Moreover, the addition of a proper amount of graphene nanosheets in ZRE coating can provide an enhanced barrier effect against aggressive species and thereby provides a less aggressive environment for corrosion of zinc particles. - Highlights: • Addition of 0.4% graphene to coating resulted in a potent protection performance. • Addition of graphene particles enhanced the percolation structure of coating. • Graphene nanosheets provided more uniform activation of sacrificial zinc particles. • Addition of insufficient amount of graphene particles resulted in a reverse effect.