Experimental study on the rheological behavior of nanolubricant-containing MCM-41 nanoparticles with viscosity measurement

In this study, the rheological behavior and viscosity of a stable nanofluid, which is prepared with the suspension of MCM-41 nanoparticles in SAE40 engine oil as base fluid, would be presented. Two-step method has been used to stabilize the nanoparticles in engine oil. To obtain structural and morphological properties of the synthesized nanoparticles, small-angle X-ray scattering, N₂ adsorption/desorption analysis and scanning electron microscopy have been done. Then, viscosity of nanofluids has been measured in temperature range of 25–55 °C, shear rates up to 13,000 s⁻¹ and different concentrations (0 mass%, 0.5 mass%, 1 mass%, 3 mass% and 5 mass% of MCM-41 nanoparticles). For all the samples, the shear stress versus shear rate diagrams showed that SAE40 oil has Newtonian behavior, in which adding mesoporous silica nanoparticles causes non-Newtonian or pseudoplastic behavior. The results declared that viscosity decreases with increasing temperature and increases with an enhancement in concentration. Furthermore, based on experimental results, an accurate correlation has been proposed to predict the viscosity of SAE40/MCM-41 nanolubricants.