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利用化学共沉淀法制备了纳米Fe3O4磁性微粒,去离子化处理后用油酸钠进行表面改性制备成水基磁流体。分别用XRD、FT-IR、SEM和VSM等手段对样品进行表征,探讨了pH值对磁流体稳定性的影响。结果表明制备的Fe3O4磁性粒子为面心立方的反尖晶石结构,平均粒径在18nm左右。磁流体中油酸钠在纳米Fe3O4粒子表面形成了双层包覆,改性后的纳米磁粒分散性良好,具有超顺磁性,饱和磁化强度较改性之前有所降低。体系的pH值可以改变Fe3O4磁性粒子的表面电荷和油酸钠的包覆效果,从而影响磁流体的稳定性,制备的磁流体在pH=7.5时具有良好的稳定性。
The nano-Fe3O4 magnetic particles were prepared by chemical coprecipitation method and deionized to prepare water-based magnetic fluid by surface modification with sodium oleate. The samples were characterized by XRD, FT-IR, SEM and VSM, respectively. The effects of pH value on the stability of magnetic fluid were also discussed. The results show that the prepared Fe3O4 magnetic particles are face-centered cubic anti-spinel structures with the average particle size of about 18 nm. Magnetic fluid sodium oleate in the nano-Fe3O4 particles formed on the surface of the double-coated, modified magnetic nanoparticles dispersed well, with super paramagnetism, saturation magnetization before modification than the decrease. The pH value of the system can change the surface charge of Fe3O4 magnetic particles and the coating effect of sodium oleate, thus affecting the stability of the magnetic fluid. The prepared magnetic fluid has good stability at pH = 7.5.