Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/3376
標題: The Study on Preparation of Magnetic Fluid with Cobalt Nano-particles
奈米鈷磁性流體製備研究
作者: 鄭惠文
Cheng, Hui-Wen
關鍵字: Magnetic fluid;磁性流體;Microwave;Ethylene glycol reduction;Cobalt Nanoparticles;微波;乙二醇還原法;奈米鈷粒子
出版社: 化學工程學系
摘要: 
磁性流體由磁性粒子、界面活性劑及溶媒所組成,為一種穩定的膠體溶液,此種膠狀液體具流動性,在外加磁場作用下又能呈現磁性,所以能應用於潤滑、密封、研磨、分選、印刷及醫藥等領域。一般在外加磁場作用下,磁性流體須符合高黏度及高磁化量的要求。而當磁性流體在外加磁場強度及其單位體積內磁性粒子的質量固定時,其磁性粒子的直徑越小,則其磁化強度越大。故本研究選用奈米鈷粒子以製備磁性流體。
首先,以醋酸鈷作為前驅物及氯化鈀與Polyvinylpyrrolidone分別為成核劑和保護劑,並藉由微波輔助乙二醇法快速合成奈米鈷粒子分散液,此利用TEM、ICP與TGA分析得知,18nm鈷粒子的轉化率為71%及45nm鈷粒子的轉化率為85%,且XRD鑑定皆為面心立方晶粒。接著,由此分散液經離心程序取出奈米鈷粒子並加入含有油酸的酒精溶液,且使用氫氧化鈉調整其pH值約為8左右,再均勻分散於煤油中,製備成油基的奈米鈷磁性流體。此利用振動樣品磁化儀(VSM)測量含有18nm及45nm鈷粒子之磁性流體的飽和磁化量分別為39.1emu/g及29.5emu/g;另外,經流變儀分析顯示所製備的磁性流體皆近似為擬塑性流體。
綜合以上成果,本研究成功地製備油基的奈米鈷磁性流體,可應用於磁場感測器、快速噴墨印刷及光開關等領域。

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.
URI: http://hdl.handle.net/11455/3376
Appears in Collections:化學工程學系所

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