Lutful Majid Aziz

US Patent:

59582820, Sep 28, 1999

Filed:

Feb 10, 1998

Appl. No.:

9/021228

Inventors:

Kuldip Raj - Merrimack NH
Lutful M. Aziz - Nashua NH

Assignee:

Ferrofluidic Corporation - Nashua NH

International Classification:

H01R 144

US Classification:

252 6252

Abstract:

A ferrofluid manufacturing process applies energy to a nonmagnetic. alpha. -Fe. sub. 2 O. sub. 3 starting material to render it magnetic and suitable for use in a ferrofluid. The material is placed, together with a solvent and a surfactant, in a commercial attrition mill where the mill action converts the non-magnetic particles to magnetic particles. In order to eliminate a solvent replacement step which is necessary with oil carrier liquids, water is used as the grinding solvent and as the ferrofluid carrier liquid. The resulting water-based ferrofluid has a high saturation magnetization, low viscosity and good colloidal stability. Using the inventive method, a large volume of fluid can inexpensively be synthesized in a short time.

US Patent:

60687851, May 30, 2000

Filed:

Feb 10, 1998

Appl. No.:

9/021229

Inventors:

Kuldip Raj - Merrimack NH
Lutful M. Aziz - Nashua NH
Ronald E. Rosensweig - Summit NJ

Assignee:

Ferrofluidics Corporation - Nashua NH

International Classification:

H01F 144

US Classification:

252 6252

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.

US Patent:

58514163, Dec 22, 1998

Filed:

Feb 12, 1997

Appl. No.:

8/798111

Inventors:

Kuldip Raj - Merrimack NH
Ronald E. Rosensweig - Summit NJ
Lutful M. Aziz - Nashua NH

Assignee:

Ferrofluidics Corporation - Nashua NH

International Classification:

H01F 144

US Classification:

252 6252

Abstract:

A ferrofluid composition comprising a colloidal dispersion of finely divided magnetic particles in a silicone oil carrier in which the surfaces of the magnetic particles are modified with (a) a first surfactant comprising a hydrocarbon having at least one polar group and (b) a second surfactant comprising a silicone oil surfactant having at least one polar group and which is soluble in the silicone oil carrier.