Tribological properties of hexagonal boron nitride nanoparticles or graphene nanoplatelets blended with an ionic liquid as additives of an ester base oil

Antifriction synergies between an ionic liquid (IL) and nanopowders as additives of an ester base oil were analysed at rolling conditions. For this aim, two nanodispersions based on hybrid combinations of hexagonal boron nitride nanoparticles (h-BN) or graphene nanoplatelets (GnP) with tri(butyl) ethylphosphonium diethylphosphate ionic liquid as additives in triisotridecyltrimellitate (TTM) base oil and the mixture of TTM and IL were analysed using two tribometer techniques. Film thickness characterisation and tribological tests were performed at rolling conditions [5% slide-roll-ratio (SRR)], under 50N and at operating temperatures of 30, 50 and 80°C. Stribeck curves showed that friction coefficients for the prepared lubricants are lower than those found for the TTM, being the best friction behaviour for the hybrid GnP nanolubricant. Furthermore, friction torque loss tests were performed in rolling ball bearings, observing that for the two hybrid nanolubricants lower friction torque values were obtained This work was supported by MINECO and the ERDF programme through ENE2017-86425-C2-2-R project, and by the Xunta de Galicia (ED431E 2018/08, ED431D 2017/06 and GRC ED431C 2020/10). JMLR acknowledges the IACOBUS programme for funding the research stay at the Porto University SI