This study investigates the characterisation and boundary tribological behaviour of palm oil (PO) as a bio-lubricant alongside its blends with MWCNTs and tert-butylhydroquinone (TBHQ) by utilising a ball-on-disc tribometer under reciprocating sliding conditions following ASTM G133. The oxidation behaviour analysis carried out using Thermogravimetry Analysis TGA shows that TBHQ can improve the oxidation stability of PO by raising the initial temperature by 23.4%, making the lubricant resilient against oxidation. From the tribological experiments performed under loads from 40 N to 120 N at 2 to 8 Hz frequency, 10 mm stroke, and 75°C temperature, PO shows a lower coefficient of friction (COF) and wear scar diameter (WSD) compared to the paraffin mineral oil (PMO) under mild conditions, but shows weak lubrication ability under severe regime due to its poor oxidation stability. However, under stiffer conditions, adding 1.2 wt.% MWCNT into PO enhances the friction characteristics by lowering the COF value by 29.3% compared to plain PO. Furthermore, the combination of MWCNTs and TBHQ exhibits synergic effect on the PO frictional properties with an improvement of up to 41% and the reduction of wear scar diameter to 0.265 mm.
Ojaomo et al. (Fri,) studied this question.