Evaluation of rheological behavior of 10W40 lubricant containing hybrid nano-material by measuring dynamic viscosity.

In the present paper, the dynamic viscosity of 10W40 lubricant containing hybrid nano-materials has been examined. Hybrid nano-materials were composed of 90% of silica (SiO 2 ) with 20–30 nm mean particle size and 10% of multi-walled carbon nanotubes (MWCNTs) with inner diameter of 2–6 nm and outer diameter of 5–20 nm. Nano-lubricant samples were prepared by two-step method with solid volume fractions of 0.05%, 0.1%, 0.25%, 0.5%, 0.75% and 1%. Dynamic viscosity of the samples was measured at temperatures between 5 and 55 °C and at shear rates of 666.5 s −1 up to 11,997 s −1 . Experimental results indicated that the nano-lubricant had non-Newtonian behavior at all temperatures, while 10w40 oil was non-Newtonian only at high temperatures. With the use of the curve fitting technique of experimental data, power law and consistency indexes were obtained; furthermore, these coefficients were assessed by shear stress and viscosity diagram. [ABSTRACT FROM AUTHOR]