不同形貌纳米Fe3O4粒子磁流体的稳定性及其流度学性能

选用无规则、正八面体和六方片状形貌的纳米Fe3O4磁性颗粒作为磁流体固相材料,通过设计组装基于L–C振荡电路的磁流体稳定性测试仪,确定制备稳定磁流体的较佳表面改性活性剂和辅助表面活性剂用量。同时,对含有不同形貌磁性颗粒的磁流体在水平方向磁场以及竖直方向磁场中的磁流变学性能进行了研究。结果表明：在外加水平方向180、350、500Gs磁感应强度,磁流体的黏度、剪切应力基本不变,磁流体表现出Newtonian流体的流变学特性;在外加竖直方向360、740、1130Gs磁感应强度,磁流体表现出Bingham流体的流变学特性;对于含有正八面体形貌纳米Fe3O4颗粒的磁流体,其黏度和剪切应力随外加磁场的变化较大。

Stability and Magneto-Rheological Properties of Magnetic Fluids Containing Fe3O4 Nano-Particles with Different Morphologies

The stability and magneto-rheological behavior of magnetic fluids containing nano-particles of Fe3O4 with irregular, octahedron and six-party flake morphologies as solid phase materials were investigated. A test device for the magnetic fluid stability, which was designed and manufactured based on the principle of L–C oscillator circuit, was used to determine the optimum organic modifier and surfactant concentrations for the preparation of the stable magnetic fluids. The magneto-rheological properties of the magnetic fluids with the nano-particles with different morphologies were examined in the presence of a vertical or horizontal magnetic field. The results show that the viscosity of magnetic fluid at various shear rates in the presence of a horizontal magnetic induction (i.e., 180, 350 and 500 Gs) could not vary. The rheologic behaviors of the magnetic fluid became a Bingham plastic fluid in the presence of a vertical magnetic induction (i.e., 360, 740 and 1 130 Gs). The viscosity and shear stress of the magnetic fluids containing the nano-particles with octahedron shape changed with the applied magnetic field.