An experimental study on the effect of concentration of green nanoadditives on the tribological properties of the biolubricants

Abstract

The paper aims to introduce a sustainable solution in the field of lubrication science. A green nano additive, hexagonal boron nitride (h-BN) is mixed with two biofriendly natural oils (avocado oil and hazelnut oil) and the tribological properties of the nanolubricants are evaluated on a four-ball tribotester. The nanoparticles are less than 100 nm in diameter and are added in varying concentrations of 0-1 wt.%. The tribological properties are evaluated as per ASTM D4172 and the stability of the nanoparticles is measured for a period of 24 hours using a double beam spectrophotometer. The UV spectroscopy results indicate the nanoparticles are stable after the sonication process and sediment very less after 24 hours. The antiwear properties of both natural oil improve with the increase in the concentration of h-BN nanoparticles. The maximum improvement in the wear properties is observed at 1 wt.% and is equal to 19.5% and 36.55% for avocado oil and hazelnut oil respectively. The improvement in the antiwear properties are ascribed to the different nanolubrication mechanisms: tribofilm formation, non-direct contact phenomenon, and entrapment of nanoparticles between wear agglomerates.