Tunable thermal conductivity and rheology of in-house synthesized Fe55Co25Ni20 complex fluids under the external magnetic field

Abstract

In the present investigation, trimetallic (FeCoNi) nanoparticles have been successfully synthesized in water (solvent) though reductive emulsion technique in the size range 10–15 nm and magnetic saturation 63 emu/g. The synthesized nanoparticles have been utilized to fabricate two types of nanofluids by using two different base mediums, namely; heat transfer oil (HTO) and ethylene glycol (EG). Experimental investigations show that the magnitude of thermal conductivity, viscosity and yield stress of the fabricated nanofluids are amplified under the influence of external magnetic field. The highest amplification in the magnitude of thermal conductivity is achieved ~0.555 W/mK and the respective augmentation for the same with respect to base nanofluid (in the absence of magnetic field) is observed ~77% at critical magnetic field 800 G and 5 vol% particles loading for the sample of FeCoNi/HTO. Moreover, maximum value of static yield stress and viscosity for the same sample are found ~7.4 kPa and ~1.9 kPa.s at 12000 G respectively. The fabricated nanofluids demonstrate excellent reversible behavior under the varying magnetic field. The findings of present investigations have utility in various fields such as automotive damping, MR brakes and clutches, hydraulic couplings etc. where thermal conductivity, viscosity as well as yield sress play an important role.