Magnetic nanofluid: synthesis and characterization

Dispersing nanoparticles in the liquid significantly alters the transport properties of the resulting fluids. Conventional coolants such as water and oils have comparatively low thermal conductivities and offer somewhat limited heat transfer coefficients to accomplish the typical cooling applications. Dispersed nanoparticles with higher thermal conductivity provide better transport properties leading to enhanced heat transfer coefficients in many devices of different size. Nanofluids which contain nanoparticles dispersed in continuous liquid phase provide many promising properties as compared to conventional fluids. In the present work, we prepared magnetic nanoparticles by the co-precipitation, followed by ultrasonication and coating with oleic acid, which were ultimately dispersed in kerosene as a carrier fluid. The agglomeration of the coated particles was thus prevented to improve their stability. The samples were analysed with various sophisticated techniques such as high-resolution transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, zeta potential, X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis, rheometry, and superconducting quantum interference device. The coated magnetic nanoparticles showed weak attraction force and offered reasonable colloidal stability of the nanofluid. Graphic abstract