US4728363A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acicular magnetic particles
Assignee: Olin Corp
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Filing: 1986-11-18
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Granted: 1988-03-01
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Expires: 2006-11-18
Abstract
Abstract The present invention relates to a method for producing magnetic particles for use in recording media. The method comprises providing an alloy capable of forming a magnetic precipitate, aging the alloy to form a magnetic precipitate comprising a plurality of magnetic particles dispersed throughout a surrounding matrix; and dissolving the matrix to leave the magnetic particles. Magnetic particles produced by the present method are characterized by a size in the range of about 100 Å to about 2000 Å, a single magnetic domain, an aspect ratio up to about 10:1, a relatively smooth surface, and a substantially uniform composition throughout.
Inventors
- 👤 Jacob Crane
- 👤 George J. Muench
- 👤 Yousef Saleh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 18:09
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70605; B; B22; B22F; B22F1/00; B22F1/06; B22F1/062; B22F9/00; B22F9/16; G11B5/712; B22F2998/00; B22F2998/10
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
28 words
Free acicular magnetic particles characterized by a face-centered cubic structure, a length in the range of 100Å to about 2000Å and an aspect ratio up to about 10:1.
Claim 2
Dependent Claim
28 words
Free acicular magnetic particles characterized by a face-centered cubic structure, a length in the range of 100Å to about 2000Å and an aspect ratio up to about 10:1.
Claim 3
Dependent Claim
35 words
The particles of claim 1 further being characterized by: said length being in the range of about 300Å to about 1500Å; and said aspect ratio being in the range of about 1.5:1 to about 8:1.
Claim 4
Dependent Claim
30 words
The particles of claim 1 further comprising: said particles containing from about 35% to about 60% nickel, up to about 15% copper, and from about 35% to about 65% iron.
Claim 5
Dependent Claim
27 words
The particles of claim 1 further comprising: said particles containing from about 40% to about 55% nickel, less than about 9% copper and the balance essentially iron.
Claim 6
Dependent Claim
13 words
The particles of claim 1 further being characterized by a single magnetic domain.
Claim 7
Dependent Claim
33 words
The particles of claim 1 further being characterized by having a saturation magnetization greater than about 80 EMU/g and a coercive field in the range of about 300 Oe to about 2000 Oe.
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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) | 1991-03-01 | 1991-08-31 | 1992-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-01 | 1995-08-31 | 1996-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-01 | 1999-08-31 | 2000-03-01 | $7700.00 | Window Closed / Lapsed |