US3671435A
Expired / Lapsed
US
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Cobalt doped gamma ferric oxide
Assignee: Ampex Corp
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Filing: 1971-07-16
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Granted: 1972-06-20
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Expires: 1991-07-16
Abstract
Abstract Acicular, cobalt doped gamma ferric oxide particles suitable for magnetic recording are produced by making an aqueous paste or slurry of a cobalt salt which will decompose below 600* C. and acicular alpha FeOOH or alpha Fe2O3. The cobalt salt is decomposed to the metal or oxide form by heating the mixture. Various cobalt and iron compounds can be used as the starting materials.
Inventors
- 👤 Paul Y Hwang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 03:48
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70652; G11B5/70668; G11B5/70673; C; C01; C01G; C01G49/00; C01G49/02; C01G49/06; C01P; C01P2002/00; C01P2002/50; C01P2002/52; C01P2002/54; C01P2004/00; C01P2004/10; C01P2004/54; C01P2004/60; C01P2004/61; C01P2004/62; C01P2006/00; C01P2006/42
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
14 words
A process in accordance with claim 1 wherein the iron compound is alpha Fe2O3.
Claim 2
Dependent Claim
12 words
The process of claim 1 wherein the iron compound is alpha FeOOH.
Claim 3
Dependent Claim
15 words
The process of claim 1 wherein the drying step (b) is conducted by spray drying.
References Cited (Backward Citations)
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US3399142A
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US3573980A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-20 | 1975-12-20 | 1976-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-20 | 1979-12-20 | 1980-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-20 | 1983-12-20 | 1984-06-20 | $7700.00 | Window Closed / Lapsed |