Patent EP0230029A2 successfully refreshed from Google Patents.
US4305752A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Metallic iron particles for magnetic recording
Assignee: ISK MAGNETICS Inc
•
Filing: 1980-06-05
•
Granted: 1981-12-15
•
Expires: 2000-06-05
Abstract
Abstract In the process for preparing a magnetically stable powder comprising the steps of reducing an iron oxide precursor with a gaseous reduction agent and stabilizing the metallic powder thus produced, the improvement which comprises coating said iron oxide precursor with an antimony compound at a level of up to about 7 weight percent antimony based on the weight of the iron oxide content of the precursor and precipitating tin hydroxides or oxyhydroxides at a level of from about 0.5 to about 8.0 weight percent tin based on the weight of the iron oxide content of the precursor onto the antimony coated iron oxide precursor prior to said reduction.
Inventors
- 👤 Louis J. Dizikes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:38
CPC Classifications
C; C21; C21B; C21B13/00; C21B13/008; B; B22; B22F; B22F1/00; B22F1/18; B22F9/00; B22F9/16; B22F9/18; B22F9/20; B22F9/22; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/061; H01F1/065; Y; Y02; Y02P; Y02P10/00; Y02P10/10; Y02P10/134; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12181
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
133 words
In the process for preparing a magnetically stable powder comprising the steps of A. Reducing an iron oxide precursor selected from the group consisting of an iron oxide, an iron oxide hydrate, a modified iron oxide or a modified iron oxide hydrate with a gaseous reduction agent; and B. Stabilizing the metallic powder thus produced, the improvement which comprises: coating said iron oxide precursor with an antimony compound at a level of up to about 7 weight percent antimony based on the weight of the iron oxide content of said precursor and precipitating tin hydroxides or oxyhydroxides at a level of from about 0.5 to about 8.0 weight percent tin based on the weight of the iron oxide content of said precursor onto the antimony coated iron oxide precursor prior to said reduction.
Claim 2
Dependent Claim
133 words
In the process for preparing a magnetically stable powder comprising the steps of A. Reducing an iron oxide precursor selected from the group consisting of an iron oxide, an iron oxide hydrate, a modified iron oxide or a modified iron oxide hydrate with a gaseous reduction agent; and B. Stabilizing the metallic powder thus produced, the improvement which comprises: coating said iron oxide precursor with an antimony compound at a level of up to about 7 weight percent antimony based on the weight of the iron oxide content of said precursor and precipitating tin hydroxides or oxyhydroxides at a level of from about 0.5 to about 8.0 weight percent tin based on the weight of the iron oxide content of said precursor onto the antimony coated iron oxide precursor prior to said reduction.
Claim 3
Dependent Claim
44 words
The process of claim 1 wherein the coated iron oxide precursor is also coated with up to about 20 weight percent of at least one metal selected from a group comprising cobalt, chromium and nickel in the form of hydroxide prior to said reduction.
Claim 4
Dependent Claim
31 words
The process of claim 1 wherein the amount of antimony employed is from about 1 to 4.5 weight percent based on the weight of the iron oxide content of said precursor.
Claim 5
Dependent Claim
19 words
The process of claim 1 wherein the antimony compound is precipitated onto the surface of the iron oxide precursor.
Claim 6
Dependent Claim
13 words
The process of claim 1 wherein the reduction is carried out in hydrogen.
Claim 7
Dependent Claim
18 words
The process of claim 1 wherein the modified iron oxide hydrate is dehydrated prior to the reduction step.
Claim 8
Dependent Claim
33 words
The process of claim 1 wherein the combined amount of antimony and tin used is up to about 7.0 weight percent based on the weight of the iron oxide content of the precursor.
Claim 9
Dependent Claim
44 words
The process of claim 1 wherein the amount of antimony and tin employed is respectively from about 0.5 to 3.5 weight percent and from about 1 to about 4 weight percent, each based on the weight of the iron oxide content of the precursor.
Claim 10
Dependent Claim
11 words
A magnetically stable powder prepared by the process of claim 1.
Claim 11
Dependent Claim
11 words
A magnetically stable powder prepared by the process of claim 2.
References Cited (Backward Citations)
US3740266A
Cited
US3607220A
Cited
US3627509A
Cited
US3623859A
Cited
US3663318A
Cited
US3837839A
Cited
US4067755A
Cited
US4063000A
Cited
US4069073A
Cited
US4056410A
Cited
US4020236A
Cited
GB2016526A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-12-14 | 1985-06-15 | 1985-12-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-12-14 | 1989-06-15 | 1989-12-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-12-14 | 1993-06-15 | 1993-12-15 | $7700.00 | Window Closed / Lapsed |