Effects of Surface Modification on the Stability of Suspension and Thermal Conductivity Enhancement of Composite Fe Nanofluids

Composite Fe nanoparticles (CINPs) were synthesized by surface modification of Fe nanoparticles with silicon alkyl ethylenediamine triacetic acid, and the silicone oil-based composite Fe nanofluids (CINPs nanofluids) were prepared with the as-synthesized CINPs and silicone oil. The surface molecular structure, magnetic properties, and surface morphology of the CINPs were characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscope, and vibrating sample magnetometer. The stability and thermal conductivity enhancement of the CINPs nanofluids were characterized via a thermal conductivity method and using a thermal property analyzer. Results show that the suspension stability of the CINPs nanofluids was greatly improved by the surface modification of the Fe nanoparticles. The thermal conductivity enhancement became more stable, and further, it was demonstrated that thermal conductivity could be tuned by applying magnetic field.