Experimental investigation about tribological performance of grapheme-nanoplatelets as additive for lubricants

Graphene has received a great interest by researchers in a wide field of applications. Referring to tribological aspects, graphene has been considered as an additive in lubricants, in order to reduce components friction and machine losses. Some papers are available in literature about graphene utilized as additive in solids or liquid lubricants. Despite the big potential of graphene in this field, its use as a lubricant or a lubricant additive on macro-meso scale remains relatively unexplored. In particular, the literature is lacking about specific applications of graphene added lubricants on mechanical systems. In this paper, the effect graphene added to a standard lubricants to create high performance compounds has been investigated. Firstly, the Coefficient of Friction (CoF) of different compositions of lubricant-graphene compounds has been experimentally evaluated. In particular, a commercial grease and two commercial oils have been chosen to be used as base lubricants. Results in terms of Coefficient of Friction values of all compounds have been compared each other. Finally, characterization results of graphene added grease have been related to that available from previous studies performed on a mechanical component (a spline coupling), commonly used in many industrial applications, lubricated by the same graphenegrease compounds. Results show that graphene added to viscous lubricants generally reduces the coefficient of friction, in both materials and components.