Enhancement of low-viscosity synthetic oil using graphene nanoparticles as additives for enduring electrified tribological environments

Knowledge of the tribological behavior of lubricants under electrified environments is relevant in electric drivelines where shaft/bearing currents exist. However, such behavior has been barely explored. In this investigation a polyalphaolefin oil (PAO4) containing 0.5 wt./v% of various surface area graphene nanoplatelets (GnPs) was tested as a potential nanolubricant for electrified environments. Thermal, electrical and rheological properties of the resulting nanolubricants were measured. Concomitantly, the tribological performance of the PAO4 and nanolubricants under unelectrified/electrified environments was evaluated by a newly implemented four-ball tester. Overall, GnPs enhanced thermal and rheological properties of PAO4, reduced dielectric strength, and improved tribological performance under electrified conditions, which suggest GnPs as effective additives to improve the properties of low-viscosity oils to withstand aggressive/undesirable electrical environments.