Process for producing a ferrofluid

Claim 1

A process for producing a ferrofluid consisting essentially of composite particles composed of polymer-attached magnetic metallic particles in indefinite suspension in a carrier fluid which consists essentially of providing a pair of electrodes, immersing the electrodes in an organic dielectric liquid, applying a pulsed electric potential between the electrodes, adjusting the gap therebetween until there is an electric discharge eroding an electrode producing particulate magnetic material containing said composite particles composed of magnetic metallic particles adherently attached to organic polymer formed by the polymerization of said dielectric liquid, said polymer being in a fibrous or filamentary form, said electrodes being formed of a metallic composition which produces said magnetic metallic particles by said erosion, recovering said magnetic material from the dielectric liquid, and dispersing said recovered material in a carrier fluid in which said composite particles become indefinitely suspended, said composite particles being in the form of filamentary rafts or membranes of a size and density which maintains them in indefinite suspension in said carrier fluid.