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US3764540A
Expired / Lapsed
US
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Magnetofluids and their manufacture
Assignee: United States Department of the Interior
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Filing: 1971-05-28
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Granted: 1973-10-09
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Expires: 1991-05-28
Abstract
Abstract Magnetofluids, comprising a stable, colloidal suspension of magnetite and elemental iron, are produced by comminuting a nonmagnetic or antimagnetic precursor compound to colloidal size, dispersing the precursor in a carrier fluid and thereafter converting the precursor to ferromagnetic forms while in stable suspension.
Inventors
- 👤 S Khalafalla
- 👤 G Reimers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:45
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/44; H01F1/445
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
35 words
The process of claim 1 wherein said dispersing step comprises agitation of the particulate suboxide and liquid mixture together with an aliphatic monocarboxylic acid dispersing agent having from about eight to about 24 carbon atoms.
Claim 2
Dependent Claim
22 words
The process of claim 1 wherein the suboxide of iron is wustite having a composition in the range of Fe0.95O to Fe0.85O.
Claim 3
Dependent Claim
23 words
The process of claim 3 wherein the wustite is converted to ferromagnetic forms by heating for a time greater than about one-half hour.
Claim 4
Dependent Claim
26 words
The process of claim 4 where the wustite is produced from finely divided ferric oxide by reduction at temperatures within the range of 570* to 800*C.
Claim 5
Dependent Claim
41 words
The process of claim 5 wherein the wustite is recovered from the reduction step in pyrophoric form and is protected from reoxidation by coating it with an aliphatic monocarboxylic acid dispersing agent having from about eight to about 24 carbon atoms.
Claim 6
Dependent Claim
18 words
The process of claim 6 wherein the dispersing agent-coated wustite is comminuted by wet grinding in the liquid.
Claim 7
Dependent Claim
19 words
The process of claim 7 wherein the liquid is a hydrocarbon and wherein the dispersing agent is oleic acid.
Claim 8
Dependent Claim
10 words
The process of claim 8 wherein the hydrocarbon is kerosene.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |