US4469506A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production process of ferromagnetic iron powder
Assignee: Mitsui Toatsu Chemicals Inc
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Filing: 1983-01-24
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Granted: 1984-09-04
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Expires: 2003-01-24
Abstract
Abstract Disclosed herein is a process for producing ferromagnetic iron powder, which process comprises adding and mixing boron oxide or a borate with alpha -FeOOH or alpha -Fe2O3 without dissolving the former, heating the thus-obtained mixture to 350 DEG C. or higher in a non-reducing atmosphere and then reducing the thus-heated mixture.
Inventors
- 👤 Haruo Sekiguchi
- 👤 Kimiteru Tagawa
- 👤 Kazushi Ohshima
- 👤 Nobuhiro Fukuda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:47
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/065; B; B22; B22F; B22F1/00; B22F1/10; B22F1/102
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
137 words
Process for producing ferromagnetic iron powder by heating a metal oxyhydroxide or oxide containing iron as its principal metallic element in a reducing atmosphere so as to reduce said metal oxyhydroxide or oxide, comprising the following consecutive steps: (a) mixing said metal oxyhydroxide or oxide with boron oxide, one or more borates or a mixture thereof at a B/Fe atomic weight ratio of 0.05/100 to 5/100 without dissolving said boron oxide or borates, so that said boron oxide or borates are dispersed in said metal oxyhydroxide or oxide; (b) heating the mixture obtained from steps (a) to a temperature of from 350° to 500° C. in a non-reducing atmosphere; and (c) reducing the heated mixture from step (b) at a temperature of from 200° to 450° C. while keeping said heated mixture in contact with hydrogen gas.
Claim 2
Dependent Claim
137 words
Process for producing ferromagnetic iron powder by heating a metal oxyhydroxide or oxide containing iron as its principal metallic element in a reducing atmosphere so as to reduce said metal oxyhydroxide or oxide, comprising the following consecutive steps: (a) mixing said metal oxyhydroxide or oxide with boron oxide, one or more borates or a mixture thereof at a B/Fe atomic weight ratio of 0.05/100 to 5/100 without dissolving said boron oxide or borates, so that said boron oxide or borates are dispersed in said metal oxyhydroxide or oxide; (b) heating the mixture obtained from steps (a) to a temperature of from 350° to 500° C. in a non-reducing atmosphere; and (c) reducing the heated mixture from step (b) at a temperature of from 200° to 450° C. while keeping said heated mixture in contact with hydrogen gas.
Claim 3
Dependent Claim
22 words
The process as claimed in claim 1 wherein said metal oxyhydroxide or oxide is acicular α-FeOOH or α-Fe 2 O 3 .
Claim 4
Dependent Claim
20 words
The process as claimed in claim 1 wherein said borates include aluminum borate, nickel borate, cobalt borate and manganese borate.
Claim 5
Dependent Claim
23 words
The process as claimed in claim 1 wherein mixing and dispersing step (a) is carried out in the absence of any dispersing medium.
Claim 6
Dependent Claim
23 words
The process as claimed in claim 1 wherein mixing and dispersing step (a) is carried out in the presence of a dispersing medium.
Claim 7
Dependent Claim
29 words
The process as claimed in claim 5 wherein the solubility of said boron oxide or one or more borates in said dispersing medium is 1 weight percent or lower.
Claim 8
Dependent Claim
18 words
The process as claimed in claim 1 wherein the B/Fe atomic weight ratio is between 0.2/100 and 2/100.
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) | 1987-09-04 | 1988-03-05 | 1988-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-04 | 1992-03-05 | 1992-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-04 | 1996-03-05 | 1996-09-04 | $7700.00 | Window Closed / Lapsed |