US3855016A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acicular cobalt powders having high squarenesss ratios
Assignee: Carlisle Memory Products Group Inc
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Filing: 1973-06-28
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Granted: 1974-12-17
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Expires: 1993-06-28
Abstract
Abstract A superior magnetic recording material is composed of acicular particles consisting predominantly of cobalt metal. The metallic particles are reduced from decomposible, acicular crystals which are prepared by a two-step precipitation process to control their size and shape. Also the crystals are immersed in an organic separating medium before and during reduction so that they do not unduly tend to agglomerate and sinter together.
Inventors
- 👤 J Ehrreich
- 👤 A Reti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:18
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/065; B; B22; B22F; B22F1/00; B22F1/16; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70605; G11B5/70621; G11B5/714; H01F1/061
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
68 words
A FERROMAGNETIC COMPOSITION FORMED OF A MASS OF ACICULAR METALLIC PARTICLES HAVING AN AVERAGE MINIMUM LENGTH OF 0.1 MICRONS AND A MAXIMUM AVERAGE DIAMETER OF 2 MICRONS AND COMPRISING AT LEAST 43 PERCENT BY WEIGHT OF COBALT, SAID MASS HAVING A COERCIVE FORCE OF AT LEAST 600 OERSTEDS; A SIGMA VALUE OF FROM 75 TO 120 E.M.U. PER GRAM; AND A SQUARENESS CHARACTERISTICS OF FROM 0.4 TO 0.5.
Claim 2
Dependent Claim
68 words
A FERROMAGNETIC COMPOSITION FORMED OF A MASS OF ACICULAR METALLIC PARTICLES HAVING AN AVERAGE MINIMUM LENGTH OF 0.1 MICRONS AND A MAXIMUM AVERAGE DIAMETER OF 2 MICRONS AND COMPRISING AT LEAST 43 PERCENT BY WEIGHT OF COBALT, SAID MASS HAVING A COERCIVE FORCE OF AT LEAST 600 OERSTEDS; A SIGMA VALUE OF FROM 75 TO 120 E.M.U. PER GRAM; AND A SQUARENESS CHARACTERISTICS OF FROM 0.4 TO 0.5.
Claim 3
Dependent Claim
24 words
A magnetic recording member comprising a carrier of nonmagentic material having bonded thereto the ferro-magnetic composition defined in claim 1, and a binder therefor.
Claim 4
Dependent Claim
28 words
A composition defined in claim 1 wherein said particles are predominatly cobalt and wherein said squareness is 0.43 or greater and said sigma value is 100 or greater.
Claim 5
Dependent Claim
24 words
A magnetic recording member comprising a carrier of nonmagnetic material having bonded thereto the ferro-magnetic composition defined in claim 3, and a binder therefor.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-16 | 1978-06-17 | 1978-12-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-16 | 1982-06-17 | 1982-12-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-16 | 1986-06-17 | 1986-12-17 | $7700.00 | Window Closed / Lapsed |