Comparison of rheological and electric properties of ER fluids based on different materials

Rheological, electric and dielectric properties of two groups of ER fluids containing zeolite or perovskite particles with different cation compositions are compared. The dielectric behaviour at low field strength and the dependence of shear stress and current density on field strength and temperature in strong electric fields have been investigated. The results show striking differences in the dielectric properties and the temperature dependence of shear stress and current density between the two groups of materials. These differences can be correlated with the crystal structures of the particles and the polarization mechanisms involved. The ER activity in zeolite-based fluids is dominated by the conductivity and attributed to the mobility of the cations. In contrast the ER activity in perovskite-based ER fluids is dominated by the dielectric constant and attributed to the local displacement of ions.