Eichhornia crassipes nanoparticles as a sustainable lubricant additive: Tribological properties optimization and performance under boundary lubrication regime

Tribological behavior of new biomaterials from Eichhornia crassipes additives were conducted in this study. Eichhornia crassipes carbon nanotubes (EC-CNT) and Eichhornia crassipes carboxymethyl cellulose (EC-CMC) polymer were used in the research, and the two additives were further optimized to examine their synergistic tendency. The friction and wear analysis was carried on the additives against base rapeseed oil using a reciprocating rig tribo-meter. The tribological enhancement of the additives were conducted in terms of friction and wear, temperature, and load-carrying effect. The substrate morphology, elemental distribution of worn surfaces was characterised using scanning electron microscope (SEM) and energy dispersive x-ray (EDX). The inclusion of 1.5 wt% EC-CNT, 0.5 wt% EC-CMC, 1.2 wt% EC-CNT + 0.4 wt% EC-CMC (optimized) in the base lubricant yielded an excellent performance as a lubricant additive and reduced the friction and wear scar volume. However, the optimized sample (1.2 wt% EC-CNT + 0.4 wt% EC-CMC) reduces friction and wear by 76.7% and 49.3%, respectively, when compared to base oil. The investigation revealed that the higher the lubricant temperature used, the better the nanoparticle tribological properties, producing best under optimized additive. The application of a load of 100 N results in the best tribofilm formation performance, resulting in reduced friction and wear.