| Summary: | 碩士 === 國立中興大學 === 化學工程學系 === 93 === Magnetic fluid is a stable colloid solution and composed of magnetic particles, surfactant and carrier. Magnetic fluid can be applied in lubrication, seal, grind, sorting, printing, and medicine etc. In general, the magnetic fluid needs to meet the requirement of high viscosity and saturation magnetism in external magnetic field. For a mass of magnetic particles per unit volume, the saturation magnetism increases with reducing the diameter of magnetic particle. Therefore, this study is to prepare magnetic fluid with cobalt nanoparticles.
Firstly, we use cobalt acetate as precursor, palladium chloride and polyvinylpyrrolidone as nuclear agent and protection agent, respectively, and then synthesize the dispersion solution with cobalt nanoparticles by microwave assisted ethylene glycol reduction. The conversion of cobalt nanoparticles with 18nm and 45nm in mean size are 71% and 85%, respectively, verified by TEM, ICP and TGA. The structure of cobalt nano-particle is a face center cubic analyzing by XRD. Next, we take cobalt nanoparticles from the dispersion solution through the centrifuging process, and add ethanol with oleic acid into it which pH value of solution is adjusted as about 8 by NaOH. Finally, the cobalt nano-particle with oleic acid is well dispersed in kerosene to formulate kerosene-based nano-magnetic fluid. As measured by vibration sample magnetometer (VSM), the saturation magnetisms of the magnetic fluid with 18nm and 45nm cobalt nanoparticles are 39.1emu/g and 29.5emu/g, respectively. Additionally, the magnetic fluids are pseudo-plastic fluid characterized by rheometer in this work
In summary, this research is successfully to fabricate kerosene-based magnetic fluid including cobalt nanoparticles. It may be used for the magnetic field sensor, quickly spurts ink printing, and the light switch and so on.
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