Since W. Winslow found the electrorheological (ER) effect in the history of the ER fluid there were mainly two generations of ER fluids developed. First, the traditional dielectric ER fluid based on the polarization interaction of dielectric particle, which can not meet the application requirements due to its low yield stress. Later, the giant ER (GER) fluids with high yield stress were developed, whose effect is caused by the orientation and interaction of polar molecules adsorbed on the particle surfaces, i.e. so called polar molecule dominant ER (PM-ER) effect. GER fluid has also not been used widely in practical applications because the polar molecules tend to were off, resulting in shear stress decreasing with running time.
    Here we introduce a new type of ER fluid called induced dipole dominant ER fluid (ID-ER), whose particles contain oxygen vacancies or conductor microclusters both prepared by high energy ball milling (HEBM) technique. In the electric field E, oxygen vacancies or conductor microclusters form induced dipoles. Since the local electric field E_loc in the gaps between particles can be two to three orders of magnitude higher than E, the induced dipole moments should be large. These strong interactions between induced dipoles cause the yield stress of the ID-ER fluid to reach more than 100kPa. On the other hand, there are oxygen vacancies or conductor microclusters everywhere in the particles. The function of the particles will not be lose due to surface wear during use, so the service life time of the ID-ER fluid can meet the requirement of use.
In this paper we would like to describe following content. The physical mechanism of ID-ER effect is proposed, and the relation between τ_y and E is τ_y∝E²; The method of preparing the particles by using HNBM, as well as the characterization of morphology, structure of the particles are given; The properties of the ID-ER fluid are presented, besides the relation of τ_y-E, the dynamic response behavior of ID-ER fluid such as response time and its change with shear rate as well as the response of shear stress with frequencies in sinusoidal E(t) field; The wear resistance of ID-ER fluid was tested and compared with PM-ER fluid. In addition, the deficiency shortcoming of ID-ER fluid is pointed out.
    The studies show that the ID-ER fluid exhibit attractive comprehensive performance, such as high yield stress, low current density (<20 μA/cm²), nice temperature stability and wear resistance, settlement resistance as well. Furthermore, the preparation method is simple, good repeatability, low cost.