Nanolubricants dispersed with graphene and its derivatives: an assessment and review of the tribological performance.

Graphene, being a path-breaking discovery of this millennium, has become one of the most researched materials lately. Recently, researchers have been exploring the possibilities of utilizing graphene as a dispersoid in a nanolubricant (a stable colloidal suspension of nanoparticles in conventional lubricant). This state-of-the-art review presents an overview of recent developments that have taken place regarding the tribological performance of different types of nanolubricants dispersed with graphene and its derivatives. The derivatives of graphene include surface functionalized graphene, graphene decorated with nanoparticles and composites of graphene with other nanomaterials. The authors have thoroughly assessed the tribological performance of graphene nanolubricants which exhibit improved tribological performances in comparison to existing lubricants. The most important parameters which affect friction characteristics of interacting solid surfaces under the influence of graphene nanolubricants are concentration of the dispersoid, number of layers of graphene nanosheets, dispersion stability and the lubrication conditions. The effects of different parameters and underlying mechanisms explaining the superior performance of these nanolubricants are thoroughly surveyed in this article. The authors also explored various domains of applications in which graphene nanolubricants, having improved tribological performance, are potential candidates for future applications.