Rheological and electrical properties of NaY zeolite electrorheological fluid

The relations between the rheological and electrical properties of NaY zeol ite electrorheological fluid and its solid phase are studied. It is found t hat then exist complex relations between its electrical and theological pro perties. The temperature spectra of dielectric properties of the fluid unde r high AC electric field are strongly field strength dependent. The relatio n between the DC conductivity of the fluid and the exciting electric field is experimentally presented as log sigma =A+BE1/2, when A is a strong funct ion, but B, a very weak function of temperature. The shear stress of the fl uid under a fixed electric field and temperature decreases with shear rate. A relaxation time for the adsorbed charges is estimated to be about 0.3 to 6.6 s in the temperature range from 280 to 380 K. The relaxation time qual itatively corresponds to the shear rate at which the shear stress begins to drop. The time dependent leaking current of the ER fluids under DC electri c held is also measured. The conductivity increase is mainly caused by the structure evolution of particles. The experimental results can he explained with the calculations of Davis (J. Appl. Phys. 81(1997) pp.1985-1991) and Martin (J. Chem. Phys. 110(1999) pp.4854-4866). It is predicted that the Na Y zeolite ER fluid strength would get degraded slowly.