Tribological and Rheological Evaluation of a Graphene Nanosheets-Based Lubricant for Metal-on-metal and Wet Clutch Interfaces

The tribological and rheological behavior of mineral oil (MO) additivated with graphene nano-sheets (GNS) as lubricant in metal-on-metal interfaces and actual wet clutch materials was analyzed in this work with a focus on its potential use in automatic transmission (AT) systems. Lubricants prepared with different GNS concentrations (0.1, 0.5, 1.0 w/v%) in MO were evaluated in shear flow (viscosity changes) and by ball-on-disc measurements. Besides, thermogravimetric analysis and wet clutch friction tests at 26 and 100 degrees C were performed. Overall, the GNS addition to MO made the lubricants non-Newtonian shear-thinning and increased their viscosity at high shear rates, reduced the wear rate for the metallic interfaces tested, and enhanced the thermal stability and oil anti-shudder property of the wet clutch.