Study On Preparation And Properties Of Nano-Magnetic Fluids

Fe3O4 nanoparticles were synthesized by chemical coprecipitation method. The effect of concentration precursor solution, Fe2+ and Fe3+ molar ratio, pH value, velocity of reaction and temperature in preparing process on the diameter and magnetic properties was systematically studied. Kerosene-based and diester-based magnetic fluids were prepared using the synthesized nanoparticles. The experiments were carried on the synthesized diester-based magnetic fluids to characterize their saturation magnetization, density, viscosity, stability and the diameter of particles. By controlling the centrifugal parameter, the author did centrifugal experiment on diester–based magnetic fluids and gained magnetic fluids on different diameter range. The saturation magnetization, density and viscosity were also examined. The magnetization curve of centrifugal magnetic fluids, the relation between density and saturation magnetization, and the relation between viscosity and saturation magnetization, are also be tested using TEM and vibrating sample magnetometer. The test was carried on starting torque with centrifugal magnetic fluids.The study proves that phase-pure, uniform and high saturation magnetization Fe3O4 nanoparticles could be obtained only when concentration precursor solution is 0.6mol/L, Fe2+ and Fe3+ molar ratio equaled 1.75, pH value exceeded 13 and temperature in preparing process is controlled from 50-60℃.The relation between the starting torque with the change of temperature and the relation between the starting torque With the change of time were drawn. It proves that the starting torque can be reduced by using centrifugal magnetic fluids.