US4381244A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ferrofluid
Assignee: Von Roll Isola USA Inc
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Filing: 1981-08-13
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Granted: 1983-04-26
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Expires: 2001-08-13
Abstract
Abstract A ferrofluid comprised of composite particles comprised of polymer-enmeshed magnetic metallic particles in indefinite suspension in a carrier fluid is produced by providing a pair of electrodes formed of a composition which will produce the desired magnetic metallic particles, 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 magnetic metallic particles enmeshed in polymer, recovering the magnetic material from the dielectric liquid and dispersing the magnetic material in a carrier fluid producing ferrofluid.
Inventors
- 👤 Ami E. Berkowitz
- 👤 John L. Walter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 00:28
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/44; H01F1/442
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
62 words
A ferrofluid consisting essentially of a carrier fluid having in indefinite suspension therein composite particles consisting essentially of magnetic metallic particles adherently enmeshed in organic polymer, said polymer being in a fibrous or filamentary form, 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.
Claim 2
Dependent Claim
62 words
A ferrofluid consisting essentially of a carrier fluid having in indefinite suspension therein composite particles consisting essentially of magnetic metallic particles adherently enmeshed in organic polymer, said polymer being in a fibrous or filamentary form, 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.
Claim 3
Dependent Claim
24 words
A ferrofluid according to claim 1 wherein said carrier fluid is selected from the group consisting of an organic fluid and an aqueous fluid.
Claim 4
Dependent Claim
13 words
A ferrofluid according to claim 1 wherein said metallic particles are elemental metal.
Claim 5
Dependent Claim
14 words
A ferrofluid according to claim 1 wherein said metallic particles are a metalic alloy.
Claim 6
Dependent Claim
14 words
A ferrofluid according to claim 1 wherein said magnetic metallic particles are metal carbide.
Claim 7
Dependent Claim
24 words
A ferrofluid according to claim 1 wherein said composite particles range from about 1% by volume to about 10% by volume of said ferrofluid.
Claim 8
Dependent Claim
18 words
A ferrofluid according to claim 1 wherein said metallic particles range in size up to about 1000 Anstroms.
Claim 9
Dependent Claim
21 words
A ferrofluid according to claim 1 wherein said metallic particles range in size from about 25 Angstroms to about 100 Angstroms.
Claim 10
Dependent Claim
78 words
A ferrofluid consisting essentially of a carrier fluid having in indefinite suspension therein composite particles consisting essentially of magnetic metallic particles adherently enmeshed in organic polymer, said magnetic particles being selected from the group consisting of iron, nickel, cobalt and alloys thereof, said polymer being in a fibrous or filamentary form, 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.
Claim 11
Dependent Claim
78 words
A ferrofluid consisting essentially of a carrier fluid having in indefinite suspension therein composite particles consisting essentially of magnetic metallic particles adherently enmeshed in organic polymer, said magnetic particles being selected from the group consisting of iron, nickel, cobalt and alloys thereof, said polymer being in a fibrous or filamentary form, 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.
Claim 12
Dependent Claim
83 words
A ferrofluid consisting essentially of a carrier fluid having in indefinite suspension therein composite particles consisting essentially of magnetic metallic particles adherently enmeshed in organic polymer, said magnetic particles being selected from the group consisting of any alloy of Fe-Si, Fe-B, Fe-Ni-Co, Fe-Ni-Co-Si, Fe-Ni-Co-B, Fe-B-Si and Fe-Co-Si-B, said polymer being in a fibrous or filamentary form, 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.
Claim 13
Dependent Claim
83 words
A ferrofluid consisting essentially of a carrier fluid having in indefinite suspension therein composite particles consisting essentially of magnetic metallic particles adherently enmeshed in organic polymer, said magnetic particles being selected from the group consisting of any alloy of Fe-Si, Fe-B, Fe-Ni-Co, Fe-Ni-Co-Si, Fe-Ni-Co-B, Fe-B-Si and Fe-Co-Si-B, said polymer being in a fibrous or filamentary form, 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.
References Cited (Backward Citations)
US2018161A
Cited
US2772761A
Cited
US2804955A
Cited
US3228882A
Cited
US3740266A
Cited
US3531413A
Cited
US3668096A
Cited
US3916038A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-04-25 | 1986-10-25 | 1987-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-04-25 | 1990-10-25 | 1991-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-04-25 | 1994-10-25 | 1995-04-26 | $7700.00 | Window Closed / Lapsed |