Abstract: A MR fluid formulation based upon a silicone liquid vehicle thickened with a treated fumed metal oxide and doped with one or more chemicals having hydrogen-bonding capability for use with natural rubber mounts. The MR fluid is resistant to settling of the magnetizable particles upon contact of the fluid with natural rubber. In one exemplary embodiment, the doping chemical is one or a combination of propylene glycol and a bifunctional ethoxylated amine.

Abstract: A magnetorheological fluid formulation comprising magnetizable particles dispersed in a non-aqueous, glycol-based liquid vehicle thickened effectively by either a fully treated fumed silica or an organoclay. The surface treated fumed silica is fully treated with a treatment molecule having a molecular weight of at least about 200. The organoclay comprises sepiolite and/or palygorskite. The glycol-based fluid advantageously consists essentially of propylene glycol and optionally ethylene glycol.

Abstract: Hydrophobic metal particles that are useful as the magnetizable particles in magnetorheological fluids and magnetorheological elastomers are provided. Hydrophilic metal particles, such as carbonyl iron particles, are made hydrophobic by reacting a surface hydroxyl on the solid metal particle with a reactive surfactant. Particles are coated with the reactive surfactant to cover at least about 90% of the surface of the particles and then washed with a low viscosity synthetic hydrocarbon to remove any excess surfactant. The particles are stabilized against oxidation and irreversible coagulation during further processing, and formulation and use in magnetorheological fluids and elastomers.