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US4686142A
Expired / Lapsed
US
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Process for the production of iron oxides epitaxially coated with cobalt the coated oxides and their cue
Assignee: Toda Kogyo Corp
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Filing: 1984-09-20
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Granted: 1987-08-11
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Expires: 2004-09-20
Abstract
Abstract In improved cobalt coated magnetic iron oxide having increased coercive field strength and highly efficient for use in magnetic recording devices and processes is produced by subjecting uncoated magnetic iron oxide particles to an acid treatment and then epitaxially coating the treated particles with cobalt.
Inventors
- 👤 Peter Kiemle
- 👤 Jurgen Wiese
- 👤 Gunter Buxbaum
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:52
CPC Classifications
C; C01; C01G; C01G49/00; C01G49/02; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70647; C30; C30B; C30B7/00; C30B7/005; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
60 words
A process for the production of magnetic iron oxides epitaxially coated with cobalt and having increased coercive field strength, comprising subjecting the magnetic iron oxides to be coated to an acid treatment before coating, said acid treatment resulting in a weight loss of iron oxides of from 2 to 30%, and then epitaxially coating the acid treated oxides with cobalt.
Claim 2
Dependent Claim
60 words
A process for the production of magnetic iron oxides epitaxially coated with cobalt and having increased coercive field strength, comprising subjecting the magnetic iron oxides to be coated to an acid treatment before coating, said acid treatment resulting in a weight loss of iron oxides of from 2 to 30%, and then epitaxially coating the acid treated oxides with cobalt.
Claim 3
Dependent Claim
38 words
A process as claimed in claim 1, characterized in that the iron oxides to be coated are γ-Fe 2 O 3 , Fe 3 O 4 or a bertholoid compound having an FeO-content of from 0 to 30%.
Claim 4
Dependent Claim
40 words
A process as claimed in claim 2, characterized in that the magnetic iron oxides to be coated contain one or more accompanying elements selected from the group consisting of P, Zn, B, Si, Sn, Ge, Al, Mn, Cr and Ni.
Claim 5
Dependent Claim
17 words
A process as claimed in claim 3, characterized in that the accompanying elements are Zn and/or P.
Claim 6
Dependent Claim
20 words
A process as claimed in claim 1, characterized in that the acids contain acid residues which form complexes with iron.
Claim 7
Dependent Claim
17 words
A process as claimed in claim 5, characterized in that the acid residues are chloride and/or oxalate.
Claim 8
Dependent Claim
39 words
A process as claimed in claim 6 characterized in that the acid concentration is in the range from 0.3 to 3N and the acid treatment is carried out at a temperature in the range from 10° to 90° C.
Claim 9
Dependent Claim
39 words
A process as claimed in claim 5, characterized in that the acid concentration is in the range from 0.3 to 3N and the acid treatment is carried out at a temperature in the range from 10° to 90° C.
Claim 10
Dependent Claim
15 words
Magnetic iron oxides epitaxially coated with cobalt obtained by the process claimed in claim 1.
Claim 11
Dependent Claim
19 words
The use of the magnetic iron oxides epitaxially coated with cobalt claimed in claim 1 for magnetic signal recording.
Claim 12
Dependent Claim
43 words
A process as claimed in claim 1, characterized in that the acid treatment is carried out up to a weight loss of iron oxide to be coated of from 5 to 20%, based on the weight of the iron oxide to be coated.
References Cited (Backward Citations)
JPS55132005A
Cited
DE3017652A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-08-10 | 1991-02-09 | 1991-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-08-10 | 1995-02-09 | 1995-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-08-10 | 1999-02-09 | 1999-08-11 | $7700.00 | Window Closed / Lapsed |