Effect of ZnO nanoparticles concentration as additives to the epoxidized Euphorbia Lathyris oil and their tribological characterization

Abstract

The disposal of the synthetic esters creates pollution and the depletion of the petroleum reserves is the issue of concern. The vegetable oil with application of nanoparticles are one of the feasible ways for providing an alternative. This study presents the tribological characteristics of Euphorbia Lathyris oil. In the initial phase, the oil was chemically modified through the epoxidation process and further addition of the zinc oxide (ZnO) nanoparticles was done. The nano lubricants were evaluated for the thermophysical characterization like viscosity, flash point, pour point with tribo analysis like friction behaviour, anti-wear mechanism, and worn surface examination using Scanning Electron Microscope. The test was performed by using a pin on disc tribometer for the tribological analysis. The viscosity of the oil shows increment with chemical modification and increase in addition to the nanoparticles. The maximum increment was observed with 8% at 100 °C temperature. The flash point increases with the addition of the nanoparticles but decrement in the pout point was observed with an increase in nanoparticles concentration. During the flow behaviour analysis, all the nano lubricant samples showed Newtonian behaviour by presenting a linear relationship between the shear rate and shear stress. During the investigation, 0.5% concentration of ZnO nanoparticles demonstrated a reduction in the coefficient of friction (COF) and wear of the pin of about 8.23% and 5.13% respectively. The SEM images also show better surfaces at 0.5% concentration due to effective lubrication to the surface.