US4010310A
Expired / Lapsed
US
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Magnetic powder
Assignee: TDK Corp
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Filing: 1975-07-21
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Granted: 1977-03-01
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Expires: 1995-07-21
Abstract
Abstract An improved magnetic powder characterized by high coercive force and high magnetic flux density which is formed by admixing a cobalt compound with a magnetic iron oxide, and adding to said admixture a complex forming agent which complexes with the cobalt compound to promote adsorption of cobalt onto the surface of the magnetic iron oxide.
Inventors
- 👤 Yuichi Kubota
- 👤 Shinji Umeki
- 👤 Yasumichi Tokuoka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:45
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; G11B5/70684; G11B5/70689; G11B5/70605; G11B5/70615; G11B5/70652; G11B5/70668; G11B5/70673; G11B5/70694; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
141 words
A magnetic powder prepared by a process, which consists essentially of: mixing a cobalt compound selected from the group consisting of CoCl 2 . 6H 2 O, CoSO 4 . 6H 2 O, CO(NO 3 ) 2 . 4H 2 O, Co(OH) 2 and CoO and 1-10 mole percent of a complexing agent selected from the group consisting of oxy acids containing a hydroxyl group and a carboxyl group or a salt thereof, ethylenediamine, ethylenediaminetetraacetic acid, acetylacetone, pyridine, dipyridyl, hydrazine, ammonia and derivatives thereof per mole of said cobalt compound, which form a cobalt complex, with acicular iron oxide characterized by a Fe + 2 /Fe + 2 ratio of 0.1-0.35; and isolating and heating said acicular iron oxide at a temperature from 200°-500° C under an inert gas such that acicular iron oxide is obtained having cobalt oxide adsorbed thereon.
Claim 2
Dependent Claim
141 words
A magnetic powder prepared by a process, which consists essentially of: mixing a cobalt compound selected from the group consisting of CoCl 2 . 6H 2 O, CoSO 4 . 6H 2 O, CO(NO 3 ) 2 . 4H 2 O, Co(OH) 2 and CoO and 1-10 mole percent of a complexing agent selected from the group consisting of oxy acids containing a hydroxyl group and a carboxyl group or a salt thereof, ethylenediamine, ethylenediaminetetraacetic acid, acetylacetone, pyridine, dipyridyl, hydrazine, ammonia and derivatives thereof per mole of said cobalt compound, which form a cobalt complex, with acicular iron oxide characterized by a Fe + 2 /Fe + 2 ratio of 0.1-0.35; and isolating and heating said acicular iron oxide at a temperature from 200°-500° C under an inert gas such that acicular iron oxide is obtained having cobalt oxide adsorbed thereon.
Claim 3
Dependent Claim
19 words
The magnetic powder of claim 1, wherein said oxy acid is citric acid, tartaric acid or a salt thereof.
Claim 4
Dependent Claim
13 words
The magnetic powder of claim 1, wherein said cobalt compound is cobalt hydroxide.
Claim 5
Dependent Claim
27 words
The magnetic powder of claim 1, wherein said cobalt compound and said complex forming agent are mixed in an alkaline solution of a pH greater than 10.
Claim 6
Dependent Claim
26 words
The magnetic powder of claim 1, wherein the amount of cobalt component adsorbed on the acicular iron oxide ranges from 1 wt% to 4.5 wt%. .
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) | 1980-02-29 | 1980-08-30 | 1981-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-29 | 1984-08-30 | 1985-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-29 | 1988-08-30 | 1989-03-01 | $7700.00 | Window Closed / Lapsed |