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Patent US4226909A successfully refreshed from Google Patents.
US4226909A
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Cobalt-doped acicular hyper-magnetite particles
Assignee: 3M Co
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Filing: 1978-08-21
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Granted: 1980-10-07
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Expires: 1998-08-21
Abstract
Abstract Acicular hyper-magnetite particles, that is, acicular particles of (FeO).sub.x Fe.sub.2 O.sub.3 where x is greater than one and not greater than 1.5, are provided with coatings of a cobalt compound, the cobalt providing 1% to 10% of the total weight of the particles. The particles provide superior magnetic recording media.
Inventors
- 👤 Thomas M. Kanten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:23
CPC Classifications
C; C01; C01G; C01G49/00; C01G49/02; C01G49/08; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; G11B5/70684; G11B5/70694; C01P; C01P2002/00; C01P2002/50; C01P2002/52; C01P2002/54; C01P2004/00; C01P2004/10; C01P2006/00; C01P2006/42; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/29; Y10T428/2982; Y10T428/2991
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
53 words
Acicular particles useful for magnetic recording media, each haviang a core consisting essentially of acicular (FeO).sub.x Fe.sub.2 O.sub.3 wherein x is greater than one and not greater than 1.5, and a surface layer comprising a cobalt compound, the cobalt being substantially only at the surface and providing 1-10% by weight of the particle.
Claim 2
Dependent Claim
53 words
Acicular particles useful for magnetic recording media, each haviang a core consisting essentially of acicular (FeO).sub.x Fe.sub.2 O.sub.3 wherein x is greater than one and not greater than 1.5, and a surface layer comprising a cobalt compound, the cobalt being substantially only at the surface and providing 1-10% by weight of the particle.
Claim 3
Dependent Claim
13 words
Acicular particles as defined in claim 1 having a carbon content of 0.5-3%.
Claim 4
Dependent Claim
11 words
Acicular particles as defined in claim 1 wherein x=1.1 to 1.4.
Claim 5
Dependent Claim
23 words
Magnetic recording media comprising a non-magnetizable carrier and a coating of acicular particles as defined in claim 1 dispersed in a nonmagnetizable binder.
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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) | 1983-10-07 | 1984-04-07 | 1984-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-07 | 1988-04-07 | 1988-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-07 | 1992-04-07 | 1992-10-07 | $7700.00 | Window Closed / Lapsed |