水基Fe3O4磁流体的制备及其性能研究

最近几年，许多研究集中在兼具液体流动性和固体磁性的双重性质的磁流体的制备上．磁流体中悬浮在液体中的固体颗粒大约10nm左右．为防止粒子团聚必须将粒子进行很好的分离，这种分离由向液体中滴加表面活性剂来完成．所以表面活性剂对形成稳定的磁流体来说是非常重要的．本文中我们找到了有效形成水基磁流体的两种表面活性剂．用化学共沉淀法制备了Fe3O4纳米粒子，并且用双层表面活性剂对粒子进行包裹．纳米粒子的大小通过XRD及TEM分别进行了表征．本文获得了粒子分散良好的稳定的水基磁流体．主要对磁流体的粘度进行了讨论．结果表明该流体的粘度很小并随外磁场增加而增加，随温度升高而降低．

PREPARATION AND THE STUDY OF PROPERTIES OF WATER- BASED Fe3O4 MAGNETIC FLUID

In recent years, many researchers have focused their attention on preparing ferrofluids, which have the fluid properties of a liquid and the magnetic properties of a solid. The ferrofluids actually contain tiny particles (~10 nm diameter) of a magnetic solid suspended in a liquid medium. The particles must be kept well separated in order to prevent the particles from agglomerating. This separation can be accomplished by adding a surfactant to the liquid medium. Therefore the surfactants are very important for forming stable ferrofluids. In the present paper we find two kinds of surfactants, which are effective for forming stable water-based ferrofluids. The nano-particles of Fe 3O 4 were prepared by a chemical co-precipitation method and the Fe 3O 4 nano-particles were coated by bilayer surfactants. The sizes of the nano-particles were charactered by XRD diffraction patterns and TEM, respectively. The stabilized water-based magnetic fluid in which the particles were dispersed well was obtained in this paper. In particular, the physics properties of the magnetic fluid were discussed. Our results show that the viscosity of the magnetic fluids is small and is increased as the applied magnetic field is increased and goes down as the temperature of the magnetic fluids is increased.