In the present work, hybrid CeO2/CuO–coconut oil nanolubricants in different weight fractions are prepared for different proportions of CeO2 and CuO namely 25/75, 50/50, and 75/25. Experimental and theoretical studies are carried out to investigate the rheological behavior of these hybrid nanolubricants with different proportions CeO2/CuO at a temperature range of 30 ℃ to 90 ℃ and various shear rates for different total concentrations (wt%) ranging from 0% to 1%. For higher concentrations and lesser shear rates, non-Newtonian behavior is observed for each proportion of CeO2 and CuO. Nanoparticle–oil interactions play an important role for non-Newtonian behavior at higher concentrations. But at higher shear rates, the nanolubricants behave as Newtonian fluids at all temperatures and concentrations. The values of viscosity measured using a rheometer shows minor variations compared to the values obtained by the theoretical models due to interactions, morphology, and size effects of nanoparticles. An empirical viscosity prediction model for hybrid CeO2/CuO–coconut oil nanolubricants is proposed in terms of concentrations for various temperatures and proportions of CeO2/CuO nanoparticles based on experimental results.
High biodegradability, renewability and low toxicity of vegetable oils make them excellent lubricating base oils. Coconut oil (CO) when used as a lubricant at metallic interfaces exhibits a low coefficient of friction but high wear rate compared to mineral oils, which limits its application as a commercial lubricant, whereas mustard oil (MO) exhibits better wear resistance. The main objective of this work is to obtain an optimal blend of MO and CO to be used as an environment-friendly base oil and to add an optimal concentration of nanoparticles as an additive to improve the viscosity and reduce the friction and wear rate. The experiments are performed on the blends with MO/(CO + MO) ratio ranging from 10 to 50% and the addition of CuO nanoparticles with concentrations ranging from 0 to 0.4 wt.%. The viscosity and tribological analyses of the CO, MO, their blends, and mineral oil (SAE20W40) are carried out and compared. Both the coefficient of friction and wear scar diameter are found to be lower than those of mineral oils. Further improvements in the tribological characteristics of the blends are attained by the addition of CuO nanoparticles in small concentrations, 0.2 wt.% being optimal.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.