Simultaneous effects of MWCNT and SiO2 on the rheological behavior of cooling oil and sensitivity analysis.

Many scholars are attracted to nano-lubricants due to their unique properties. In the present study, the rheological behavior of a new generation of lubricants has been investigated. SiO(2) nanoparticles with an average diameter of 20-30 nm along with MWCNT with an internal diameter of 3-5 nm and the external diameter of 5-15 nm has been dispersed in 10W40 engine oil as base-lubricant and MWCNTs-SiO2 (20%-80%)/10W40 hybrid nano-lubricant has been produced. Nano-lubricant behavior agrees with the Herschel-Bulkley model and is of Bingham pseudo-plastic type below 55°C . Also, in the temperature of 55°C , nano-lubricant behavior has changed to Bingham dilatant. The viscosity is increased by 32% in the proposed nano-lubricant compared to base lubricant (Dynamics Viscosity Enhancement). Finally, a new correlation with a precision index of R-squared >0.9800, Adj. R-squared >0.9800, and the maximum margin of deviation of 2.72% has been presented, increasing the applicability of this nano-lubricant. Eventually, the sensitivity analysis of nano-lubricant has been conducted, studying the comparative effect of volume fraction and temperature on viscosity.