Graphene derivatives reinforced metal matrix nanocomposite coatings: A review

Due to the extraordinary mechanical, thermal, and electrical properties of graphene, graphene oxide (GO), and reduced graphene oxide (rGO), these materials have the potential to become ideal nanofillers in the electrodeposited nanocomposite coatings. This article provides an overview of literature on the improvements of properties associated with graphene, GO, and rGO-reinforced coatings, along with the processing parameters and mechanisms that would lead to these improvements in electrodeposited metal matrix nanocomposite coatings, where those affected the microstructural, mechanical, tribological, and anti-corrosion characteristics of coatings. The challenges associated with the electroplating of nanocomposite coatings are addressed. The results of this survey indicated that adding graphene into the plating bath led to a finer crystalline size in the composite coating due to increasing the potential development of specific crystalline planes and the number of heterogeneous nucleation sites. This consequently caused an improvement in hardness and in tribological properties of the electrodeposited coating. In graphene reinforced metallic composites, the severe adhesive wear mechanism for pure metallic coatings was replaced by abrasive wear and slight adhesive wear, where the formation of a tribolayer at the contact surface increased the wear resistance and decreased friction coefficient. Furthermore, superhydrophobicity and smaller grain size resulted from embedding graphene in the coating. It also provided a smaller cathode/anode surface ratio against localized corrosion, which has been found to be the main anti-corrosion mechanism for graphene/metal coating. Lastly, the study offers a discussion of the areas of research that need further attention to make these high-performance nanocomposite coatings more suitable for industrial applications.