关于磁性液体研究中的一些问题

Study on Some Problems in Magnetic Liquid

一种性能优良的磁流体,应当是超微磁性粒子分散在基液中,有着一定浓度的稳定的悬浮体。但是就这类材料本身的一些问题,相对来看,却很少引起人们的关注。表面活性剂通常为这种胶体提供稳定性。即使采用非磁性超微粒子,也很难制成长期稳定的悬浮体,因为,在不同环境中,存在着聚集作用、蒸发和化学变化。磁流体中的超微磁性粒子因氧化问题,使它不可能具有较高的磁化强度;一些最有意义的基液正期待着开发相应的表面活性剂,而那些最常用的液体,却应当选择不易被氧化和不易被水解的表面活性剂。最理想的表面活性剂,则是那些永久地附着在粒子界面上的表面活性剂。关于聚集作用,主要问题是往往被人们忽视了。一些简便易行的定量检测和清除聚集体的方法,将是最受欢迎的。

A good magnitic fluid is a concentrated stable suspension of fine magnetic particles, but the problems concerning the materials themselves have attracted relatively little attention. A surfactant normally provides the colloidal stability. Even with non-magnetic particles it is difficult to make a concentrated suspension that has a long time stalility without aggregation, evaporation and chemical changes when this suspension is expoxed to various environments, In this paper we will discuss these practical problems. The use of particales materials with higher magnetization in magnetic fluids is hindered by oxidation problems. The most attractive base fluids are waiting for the matching surfactants. For the usual base liquids, non-oxidizable, non-hydrolysable surfactants should be selected. Even the disirable surfactants are what are attracted permanently to the surface. Simple methods for the quantitative determination and removal of aggregates would be welcome.