SYNTHESIS AND MAGNETIC PROPERTIES OF Ni NANOPARTICLES

This study proposes a new method of using the arc-submerged nanofluid synthetic system to fabricate Ni nanoparticles. The proposed system has the advantages of high-power electric arc heating system, excellent stability of the electric arc, and well-developed control technology. This system uses the energy produced by arc discharge to melt and vaporize pure nickel rod under vacuum conditions. The vaporized metal is cooled rapidly inside a low-temperatured dielectric liquid, forming Ni nanoparticles that are evenly distributed inside the dielectic liquid. Experiments prove that the mean particle size of the Ni nanoparticles fabricated by this system is 20 nm. Their size is very consistent and the suspension of fabricated nanofluid is highly stable. This paper further investigates the influence of pH value and Zeta potential of the nanofluid on its suspension stability. Results of inspecting the magnetic properties show that the fabricated Ni nanofluid is similar to a Newtonian fluid, since residual magnetization and coercive force do not exist therein. Moreover, the Ni nanoparticles exhibit superparamagnetism. In addition, when Ni particles are worked under applied magnetic field, the particles would move in the direction of magnetic field. When the magnetic field is removed, the particles stop moving and still remain stably suspend in the dielectric liquid.