Lubricants play a major role in mechanical machines and studies on various nanolubricants are reported in the literature. This work deals with nanolubricants using blend of oils as base for nanolubricants. Nano-blended lubricants were prepared with a blend of ISO VG46 oil (mineral oil) and Jatropha oil (non-edible vegetable oil) and using them in proportions of 90:10 and 80:20 by dispersing 0.5–3 wt.% of surface-modified CuO nanoparticles by a two-step method. Various properties of these oils such as dispersion stability, viscosity and thermal conductivity were determined. Experimental values of viscosity were compared with the values predicted by using different viscosity models. Nano-blended lubricant 9010 was found more sensitive at lower concentration of nanoparticles compared to nano-blended lubricant 8020. It is observed that nano-blended lubricant 9010 with 1.5 wt.% CuO is more suitable for use in place of ISO VG46 oil compared to nano-blended lubricant 8020. Thermal conductivity values of all types of nano-blended lubricants have been found by thermal conductivity model to be approximately matching with the measured values.

In this experimental study, three stable nano-bio-lubricants were prepared by dispersing CuO nanoparticles in three bio-lubricants and later investigations were carried out to determine pressure distribution and frictional performance of ISO VG46 oil, bio-lubricants and nano-bio-lubricants in hydrodynamic journal bearing under different loads and speeds. The experimental results revealed that pressure of oils inside bearing depends on viscosity of oils. Addition of nanoparticles in bio-lubricants did not help to enhance the maximum pressure of oil inside bearing. Frictional performance of ISO VG46 oil and bio-lubricants was according to their viscosity but coefficient of friction of nano-bio-lubricants was higher compared to ISO VG46 oil inspite of having approximately same viscosity compared to ISO VG46 oil. Among all the oils, ISO VG46 oil and bio-lubricant 9010 had similar performance and hence Bio-lubricant 9010 can be used in place of ISO VG46 oil in journal bearing.

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This article presents experimental results on the mixing of CuO nanoparticles in ISO VG 46 oil, Jatropha oil, and a blend of the two oils. Initially, blend oil was prepared by mixing ISO VG46 and Jatropha oil in a fixed proportion. This blending caused a reduction in the viscosity of the oil mix as compared to the ISO VG46 oil. Therefore, to bring the viscosity of the blend oil to the level of the ISO VG46 oil, various concentrations of CuO nanoparticles were added to the blend to prepare stable nano-blend oils. The stability of the blend oil, ISO VG46, and Jatropha oil-based nano-lubricants was checked by measuring viscosity at regular intervals of time, and it is observed that stability decreases with the increase of CuO loading in base fluid. Viscosity values of nano-blend oils for various concentrations of CuO ranging from 0 to 3 wt. % were measured. These values were compared to the viscosity values of ISO VG46 and Jatropha oil-based nano-lubricants with the same CuO concentrations. About 19, 17, and 20 % enhancement in viscosity was observed in the blend oil, ISO VG46 oil, and Jatropha oil-based nano-lubricants, respectively, for 3 wt. % concentrations of CuO at 30°C. The nano-blend oil showed inferior performance up to 2 wt. % concentration of CuO in the entire temperature range (30 to 60°C). The viscosity of the nano-blend oil dispersing with 3 wt. % concentration matched well with the viscosity of ISO VG46 mineral oil. Furthermore, the experimental viscosity data of all the types of nano-lubricants are compared to the different viscosity models, and it is observed that the viscosity of the nano-lubricants closely matched with a viscosity model available in the literature. It is observed from viscosity sensitivity analysis that viscosity is more sensitive to greater concentration. The studies on the effects of nanoparticles’ concentration on density and friction coefficients revealed that the addition of nanoparticles in base oils had a small impact on pumping power.