Chain formation in a complex fluid containing carbon cones and disks in silicon oil

We demonstrate the chain formation of an electrorheological fluid consisting of carbon cones/disks in silicon oil. Chain structures are found to form only in the presence of an ac electric field. The field required may be as low as approximately 50 V/mm. The kinetics of the chain formation is found to depend strongly on particle concentration and on the electric field applied. The growth rate of the chain length may be described by an exponential function of the electric field. The formation of chains is slow compared to that of conventional electrorheological fluids, with a percolation time of about 1–2 min for an ac electric field of about 400 V/mm.