US5221322A
Expired / Lapsed
US
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Method of making ferromagnetic ultrafine particles
Assignee: TDK Corp
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Filing: 1992-03-23
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Granted: 1993-06-22
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Expires: 2012-03-23
Abstract
Abstract Ultrafine particles of Fe-Co-P material with a Fe/Co atomic ratio of from 95/5 to 70/30 and a (Fe+Co)/P atomic ratio of from 85/15 to 60/40 show improved ferromagnetic properties. The average particle size is from 0.005 to 0.1 mu m. Such ultrafine particles are prepared through gas phase reaction by evaporating a source material. They are useful in both magnetic and thermomagnetic recording media ensuring high density recording.
Inventors
- 👤 Yasumichi Tokuoka
- 👤 Jiro Yoshinari
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:15
CPC Classifications
B; B22; B22F; B22F9/00; B22F9/16; B22F9/18; B22F9/28; B22F9/02; B22F9/12; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/10; H01F1/11
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
40 words
A method for preparing ferromagnetic ultrafine particles comprising evaporating a powder source material containing at least iron, cobalt and phosphorus in a gas phase in a furnace, and quenching the vapor into ferromagnetic ultrafine particles containing iron, cobalt and phosphorus.
Claim 2
Independent Claim
40 words
A method for preparing ferromagnetic ultrafine particles comprising evaporating a powder source material containing at least iron, cobalt and phosphorus in a gas phase in a furnace, and quenching the vapor into ferromagnetic ultrafine particles containing iron, cobalt and phosphorus.
Claim 3
Dependent Claim
15 words
The method of claim 1 wherein the evaporating step includes heating with a thermal plasma.
Claim 4
Dependent Claim
26 words
The method of claim 1 wherein said powder source material is constructed of source material particles having a mean particle size of up to 100 μm.
Claim 5
Dependent Claim
29 words
The method of claim 1 wherein said furnace has an inner wall formed of a carbon-containing material whereby ferromagnetic ultrafine particles containing, iron, cobalt, phosphorus, and carbon are obtained.
Claim 6
Dependent Claim
30 words
The method of claim 1 wherein said powder source material contains at least iron, cobalt, phosphorus and carbon whereby ferromagnetic ultrafine particles containing iron, cobalt, phosphorus, and carbon are obtained.
Claim 7
Dependent Claim
28 words
The method of claim 1 wherein the gas phase used in the evaporating step contains nitrogen whereby ferromagnetic ultrafine particles containing iron, cobalt, phosphorus, and nitrogen are obtained.
Claim 8
Dependent Claim
34 words
The method of claim 1 wherein the ferromagnetic ultrafine particles are of a composition having a Fe/Co atomic ratio of from 95/5 to 70/30 and a (Fe+Co)/P atomic ratio of from 85/15 to 60/40.
References Cited (Backward Citations)
US4305753A
Cited
JPS63266008A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-06-21 | 1996-12-21 | 1997-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-06-21 | 2000-12-21 | 2001-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-06-21 | 2004-12-21 | 2005-06-22 | $7700.00 | Window Closed / Lapsed |