Compositions – Magnetic – Flaw detection or magnetic clutch
Patent
1998-02-10
2000-05-30
Koslow, C. Melissa
Compositions
Magnetic
Flaw detection or magnetic clutch
252 6256, 252 6254, H01F 144
Patent
active
060687851
ABSTRACT:
A slurry is formed of particles of a non-magnetic oxide of iron (.alpha.-Fe.sub.2 O.sub.3), an oil carrier liquid and a surfactant. The slurry is then processed in an attrition mill where kinetic energy is applied to the slurry to convert the .alpha.-Fe.sub.2 O.sub.3 particles to magnetic iron oxide particles to form an oil-based ferrofluid. In order to increase the saturation magnetization of the resulting ferrofluid, a beneficial agent is brought into contact with the slurry during processing in the attrition mill. The beneficial agent can be a magnetic material, such as elemental iron, or can be water. A ferrofluid can also be formed by creating a powder of surfactant-coated magnetic particles and using an attrition mill to coat the particles with a second surfactant and suspend the coated particles in a carrier liquid.
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Aziz Lutful M.
Raj Kuldip
Rosensweig Ronald E.
Ferrofluidics Corporation
Koslow C. Melissa
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