Investigation on the rheological behavior of coconut oil based hybrid CeO₂/CuO nanolubricants

Abstract

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.

Experimental study on rheological properties of vegetable oils mixed with titanium dioxide nanoparticles

“…It is observed that all vegetable oils mixed with TiO 2 nanoparticles obey a quadratic polynomial equation as given by Eq. (13) A similar observation is made by Sajeeb et al [30] in their study of mixing coconut oil with oxide nanoparticles. The empirical constants ('A' and 'B') and correlation coefficient for different vegetable oils at different temperatures is shown in Table 7.…”

Tribological assessment of vegetable oil based CeO2/CuO hybrid nano-lubricant

“…The SEM image and XRD results of the CeO 2 and CuO nano-particles used in this study were detailed in the previous study. 22…”

“…21 experimentally studied the effect of Al 2 O 3 /TiO 2 hybrid nano-lubricants on the efficiency and fuel economy of engines and reported that there is a reduction in frictional power losses. Sajeeb and Rajendrakumar 22 detailed that the CO based CeO 2 /CuO: 50/50 hybrid nano-lubricant is found to enhance rheological characteristics of base oil (CO). The additive properties of Ag–MoS 2 nano-particles were investigated by Zhang et al.…”

“…The performance of Al 2 O 3 /TiO 2 nano-composite in engine oil has been studied tribologically by Luo et al 20 Ali et al 21 experimentally studied the effect of Al 2 O 3 /TiO 2 hybrid nano-lubricants on the efficiency and fuel economy of engines and reported that there is a reduction in frictional power losses. Sajeeb and Rajendrakumar 22 detailed that the CO based CeO 2 / CuO: 50/50 hybrid nano-lubricant is found to enhance rheological characteristics of base oil (CO). The additive properties of Ag-MoS 2 nano-particles were investigated by Zhang et al 23 and reported that there is a reduction in friction coefficient and improvement in lubrication efficiency with Ag-MoS 2 nano-lubricant.…”

Effect of Mixing Temperature, Ultrasonication Duration and Nanoparticles/Surfactant Concentration on the Dispersion Performance of Al2O3 Nanolubricants

“…Some researchers have also carried out research on the preparation factors of nanolubricants and the dispersion and stability of nanoparticles in various lube oils, and analyzed the failure reasons. As shown in Table 1, although nanoparticles dispersed in various oils have been proven to be effective in reducing friction, improving anti wear properties and thermal conductivity, the duration of dispersion stability is still unsatisfactory [1,3,22,[27][28][29][30][31][32][33][34][35][36][37][38][39].…”