Tribological properties of dispersions based on reduced graphene oxide sheets and trimethylolpropane trioleate or PAO 40 oils

The main goal of this work is to study the tribological properties of nanolubricants formed by trimethylolpropane trioleate (TMPTO) or a polyalphaolefin (PAO 40) base oils with reduced graphene oxide sheets (rGO). This reduction was carried out in order to have a good stability of the nanoadditives in the fluids. For this aim, rGO nanopowders were prepared by thermal reduction of graphene oxide (GO) powders using KOH/ethanol as reducing agent. Tribological behavior of nanolubricants based on TMPTO and on PAO 40 oils with 0.05, 0.10, 025 and 0.50 wt% of rGO was evaluated. The tribological tests were carried out with a tribometer operating in ball on disk configuration and rotational mode under a working load of 20 N at room temperature. In order to analyze the wear track through the width, depth and cross-section area of the scar, a 3D optical profilometer was used. The best antifriction performance was found for 0.25 wt% rGO nanodispersions, with a 24% and a 20% enhancement for the PAO 40 and the TMPTO base oils, respectively. Moreover, for this last nanodispersion, a reduction of 24% in the wear track width was obtained. (C) 2018 Elsevier B.V. All rights reserved.