Electrorheological fluids comprising carbonaceous particulates dispersed

Abstract

Electrorheological fluids display swift and reversible increase in apparent viscosity under application of an electrical potential difference to the fluid, and are composed generally of electrical insulating oily medium and dielectric fine-particles dispersed therein. At the initial stage of development, electrorheological fluids are prepared by dispersing water-carrying hydrophilic particulates in an electrical insulating oily medium. However, there are such defects as a restriction on usable temperatures so as to avoid evaporation or freezing of the water, an extreme increase in the electric current flow as the temperature raises, inferior stability caused by transfer of water etc. It is an object of the persent invention is to provide nonaqueous type electrorheological fluids having improved electrorheological property. The electrorheological fluid of the present invention is a nonaqueous type electrorheological fluid which comprises organic or inorganic particulates containing not more than 1 wt. % of water and dispersed in an oily medium superior in electrical insulation, wherein the improvement is that said fluid comprises from 0.001 wt. % to 10 wt. % of a compound having a functional group containing at least one atom selected from the group consisted of oxygen atom, nitrogen atom, sulfur atom and phosphorous atom.