US3607220A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing a magnetically stable powder consisting mainly of iron for magnetic recording
Assignee: US Philips Corp
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Filing: 1969-02-26
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Granted: 1971-09-21
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Expires: 1989-02-26
Abstract
Abstract Iron powder suitable for use as a magnetic recording medium is prepared by first subjecting a finely divided iron oxide or oxyhydrate such as Alpha -Fe203, gamma -Fe203, Alpha -Fe00H, gamma -Fe00H or Fe304 to the action of a 0.002 to 1 molar solution in water of stannous chloride and thereafter reducing the iron oxide or oxyhydrate, preferably in hydrogen, followed by stabilizing the iron powder thus obtained.
Inventors
- 👤 Aart Antonie Vandergiessen
- 👤 Cornelis Johannes Klomp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 13:27
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/065; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70605; G11B5/70615
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
14 words
A method as claimed in claim 1, wherein hydrogen is the gaseous reduction agent.
Claim 2
Independent Claim
36 words
A method as claimed in any of the claims 1 wherein the iron oxide and the iron oxide hydrate, before being reduced is treated with a 0.004 to 0.04 molar solution of stannous chloride in water.
References Cited (Backward Citations)
US2660522A
Cited
US2879154A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |