Electrorheology of a zeolite/silicone oil suspension with dc and ac fields

The electrorheology of a zeolite/silicone oil suspension with direct current (dc) and alternating current (ac) electric fields was determined at room temperature. The shear yield stress changed only slightly with the field frequency, but the current density increased considerably. Good agreement occurs between the experimental results and those predicted by our model for both the shear yield stress and the current density. This study shows that there is a significant electrorheological (ER) effect over a large frequency range when a suspension has both a high conductivity ratio and a high dielectric ratio of the particles to the host oil.