TRIBOLOGICAL STUDIES ON GRAPHENE/TMP BASED NANOLUBRICANT

This paper presents studies on density, dynamic viscosity and tribological behaviour of nano graphene platelets (NGPs) dispersed in Palm Oil Trimethlolpropane (TMP) ester base lubricant. NGPs with concentrations ranging from 0.01 to 0.1 wt% are dispersed in the TMP ester via water bath sonication for 4 hours to form stable NGP nanolubricants. Physical properties such as density and viscosity was measured using Portable density meter and Brookfield viscosmeter (DV II+). No significant enhancement in density was observed, while a maximum enhancement on viscosity was 168% at 0.1 wt % NGPs concentration. The evaluation of frictional coefficient was performed using a four ball test at varying loads, from 40 kg to 80 kg, respectively. Results showed that the introduction of NGPs as an additive in the TMP lubricant reduced the coefficient of friction (COF) in NGP-Palm oil TMP Ester, achieving a maximum reduction of 7%, and 16.2% in the wear scar diameter at 0.05wt% NGP and 80 kg load. It was observed that addition of NGP has prevented oxidative attacks on the surface of the steel balls through the development of a sturdier lubricating film barrier between nanolubricant and the solid surfaces.