US3903004A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing magnetic powder of cobalt-substituted gamma-ferric oxide
Assignee: Panasonic Holdings Corp
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Filing: 1973-09-07
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Granted: 1975-09-02
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Expires: 1993-09-07
Abstract
Abstract The present invention relates to improved cobalt-substituted gamma -ferric oxide magnetic powder suitable for application in magnetic recording. Said powder comprises a batch composition which is characterized by addition of controlled amounts of at least one compound selected from the group of NH4, Cu, Li, Pb, Sn, Ba, Cd, Sr and In halide compounds to the mixture of acicular powder of goethite with a controlled amount of cobalt compound, said batch composition being mixed, heated at a temperature from 300* to 600*C in a reducing gas atmosphere, and finally oxidized at a temperature from 150*C to 350*C in air or oxygen gas atmosphere.
Inventors
- 👤 Keiji Matsumoto
- 👤 Yoshihiro Matsuo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 00:52
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70652; G11B5/70668; G11B5/70673
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
170 words
A METHOD OF PREPARING A MAGNETIC POWDER CONSISTING MAINLY OF COBALT-SUBSTITUTED Y-FERRIC OXIDE, WHICH ESSENTIALLY COMPRISES DISPERSING ACICULAR POWDER OF GOETHITE INTO AN AQUEOUS SOLUTION OF A COBALT COMPOUND,PRECIPITATING ALL OF THE COBALT IONS IN THE FORM OF COBALT HYDROXIDE BY ADDITION OF A PRECIPITATING REAGENT INTO THE AQUEOUS SOLUTION OF COBALT COMPOUND, FILTERING THE RESULTANT MIXTURE OF GOETHITE AND COBALT HYDROXIDE, THE ATOMIC PERCENT OF FE IN SAID GOETHITE-COBALT HYDROXIDE MIXTURE BEING 90.0 TO 99.5 AND THE ATOMIC % OF CO BEING 0.5 TO 10.0, MIXING 0.5 TO 15 MOL. % IN TOTAL, OF AT LEAST ONE HALIDE SELECTED FROM THE GROUP CONSISTING OF NH4X, CUX, LIX, PBX2, SNX2, BAX2, SRX2 AND INX3, WHEREIN X IS F, C1, BR OR 1, WITH 85 TO 99.5 MOL. % OF THE MIXTURE OF GOETHITE AND COBALT HYDROXIDE, HEATING THE FINAL MIXTURE AS A TEMPERATURE FROM 300*CTO 6000*C IN A REDUCING GAS ATMOSPHERE, AND FINALLY OXIDIZING THE FINAL MIXTURE AT A TEMPERATURE FROM 150*C TO 350*C IN AIR OR OXYGEN GAS ATMOSPHERE.
Claim 2
Independent Claim
170 words
A METHOD OF PREPARING A MAGNETIC POWDER CONSISTING MAINLY OF COBALT-SUBSTITUTED Y-FERRIC OXIDE, WHICH ESSENTIALLY COMPRISES DISPERSING ACICULAR POWDER OF GOETHITE INTO AN AQUEOUS SOLUTION OF A COBALT COMPOUND,PRECIPITATING ALL OF THE COBALT IONS IN THE FORM OF COBALT HYDROXIDE BY ADDITION OF A PRECIPITATING REAGENT INTO THE AQUEOUS SOLUTION OF COBALT COMPOUND, FILTERING THE RESULTANT MIXTURE OF GOETHITE AND COBALT HYDROXIDE, THE ATOMIC PERCENT OF FE IN SAID GOETHITE-COBALT HYDROXIDE MIXTURE BEING 90.0 TO 99.5 AND THE ATOMIC % OF CO BEING 0.5 TO 10.0, MIXING 0.5 TO 15 MOL. % IN TOTAL, OF AT LEAST ONE HALIDE SELECTED FROM THE GROUP CONSISTING OF NH4X, CUX, LIX, PBX2, SNX2, BAX2, SRX2 AND INX3, WHEREIN X IS F, C1, BR OR 1, WITH 85 TO 99.5 MOL. % OF THE MIXTURE OF GOETHITE AND COBALT HYDROXIDE, HEATING THE FINAL MIXTURE AS A TEMPERATURE FROM 300*CTO 6000*C IN A REDUCING GAS ATMOSPHERE, AND FINALLY OXIDIZING THE FINAL MIXTURE AT A TEMPERATURE FROM 150*C TO 350*C IN AIR OR OXYGEN GAS ATMOSPHERE.
Claim 3
Dependent Claim
11 words
A method as claimed in claim 1, wherein X is Br.
Claim 4
Dependent Claim
11 words
A method as claimed in claim 1, wherein X is I.
Claim 5
Dependent Claim
11 words
A method as claimed in claim 1, wherein X is F.
Claim 6
Dependent Claim
31 words
A method as claimed in claim 1, wherein said cobalt compound in an aqueous solution is at least one member selected from the group consisting of CoSO4, CoCl2, Co(NO3)2, and Co(CH3COO)2.
Claim 7
Dependent Claim
12 words
A method as claimed in claim 1, wherein said halide is NH4Cl.
Claim 8
Dependent Claim
12 words
A method as claimed in claim 1, wherein said halide is CuCl.
Claim 9
Dependent Claim
12 words
A method as claimed in claim 1, wherein said halide is LiCl.
Claim 10
Dependent Claim
12 words
A method as claimed in claim 1, wherein said halide is PbCl2.
Claim 11
Dependent Claim
12 words
A method as claimed in claim 1, wherein said halide is SnCl2.
Claim 12
Dependent Claim
12 words
A method as claimed in claim 1, wherein said halide is BaCl2.
Claim 13
Dependent Claim
12 words
A method as claimed in claim 1, wherein said halide is SrCl2.
Claim 14
Dependent Claim
12 words
A method as claimed in claim 1, wherein said halide is InCl3.
Claim 15
Dependent Claim
11 words
A method as claimed in claim 1, wherein X is Cl.
References Cited (Backward Citations)
US3075919A
Cited
US3399142A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-01 | 1979-03-03 | 1979-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-01 | 1983-03-03 | 1983-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-01 | 1987-03-03 | 1987-09-02 | $7700.00 | Window Closed / Lapsed |