铁粒子多分散系统磁流变液的制备和性能研究

Fabrication and Performance Studies of Iron Particle Polydispersity on Magnetorheological Fluids

磁流变液是铁磁性颗粒分散到低粘度的油中形成的稳定的悬浊液。其扩散特性主要由颗粒本身的物性和颗粒间的相互作用而决定。为了更好的控制颗粒间的相互作用，我们加入同样物性，但尺寸更小的颗粒，以调控悬浊液的流动特性。研究显示，在高体积百分比的磁流变液中加入亚微米尺寸的铁颗粒可以显著改善流体在没有外加磁场情况下的流动特性。受范得华力影响，加入的小颗粒首先附着在大颗粒周围，形成组装体，组装体间范得华力较小，从而有效降低了流体粘度。流体的粘度随着小颗粒在大颗粒上附着的比例不同而变化。随着小颗粒的增加，流体中铁颗粒的体积百分比增加，从而提高了磁流变液在磁场中的屈服应力，增强了磁流变液的磁流变效果。

The dispersion of metal particles in oil is used to manufacture magnetorheological fluids. The properties of these dispersions are mainly determined by the nature and the dispersion structure of the particles. In order to control these contacts, particles of the same nature but of smaller size are added. These additions have considerable effects on the viscoelastic properties of dispersions. The study examined the effects of the addition of submicrometer particles on the dispersion of magnetorheological fluids of high volume concentrations. Out of the magnetic field, the viscosity of fluid depends mostly on the adhesion of small particles, and was directly related to the fraction of small particle coverage. In the magnetic field, the yield stress was directly in proportion to the mass of iron particles. The quantity of small particles appended to the fluid determines the difference of yield stress of magnetorheological fluid in/out of the magnetic field.