US3902888A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing ferromagnetic alloy powder
Assignee: Fujifilm Holdings Corp
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Filing: 1974-07-29
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Granted: 1975-09-02
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Expires: 1994-07-29
Abstract
Abstract A process for preparing a ferromagnetic alloy powder comprising reducing salts of ferromagnetic metals in an aqueous solution containing an acicular fine powder in the presence of hypophosphite ion is disclosed. The aqueous solution can be subjected to the action of a magnetic field or ultrasonic waves during the reaction if desired, and the rate of the reaction can be increased by the addition to the aqueous solution of a noble metal ion.
Inventors
- 👤 Masashi Aonuma
- 👤 Tatsuji Kitamoto
- 👤 Goro Akashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:38
CPC Classifications
B; B22; B22F; B22F9/00; B22F9/16; B22F9/18; B22F9/24; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/061; H01F1/065
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
86 words
IN A PROCESS FOR PREPARING A FERROMAGNETIC ALLOY POWDER OF A COABLT OR COBALT-NICKEL ALLOY SYSTEM, WHICH PROCESS COMPRISES REDUCING SALTS OF THE FERROMAGNETIC METALS IN AN AQUEOUS SOLUTION IN THE PRESENCE OF HYPOPHOSITE ION TO FORM A FERROMANETIC ALLOY POWDER, THE IMPROVEMENT WHICH COMPRISES INCORPORATING ACICULAR FINE POWDERS WHICH ARE NOT THE SAME SUBSTANCE AS THE FERROMAGNETIC ALLOY INTO SAID AQUEOUS SOLUTION UPON WHICH SAID FERROMAGNETIC ALLOY PRECIPITATES, SAID FERROMAGNETIC ALLOY POWDER CONSISTING ESSENTIALLY OF SAID ACICULAR FINE POWDER HAVING LAYERED THEREAROUND SAID FERROMAGNETIC ALLOY.
Claim 2
Dependent Claim
86 words
IN A PROCESS FOR PREPARING A FERROMAGNETIC ALLOY POWDER OF A COABLT OR COBALT-NICKEL ALLOY SYSTEM, WHICH PROCESS COMPRISES REDUCING SALTS OF THE FERROMAGNETIC METALS IN AN AQUEOUS SOLUTION IN THE PRESENCE OF HYPOPHOSITE ION TO FORM A FERROMANETIC ALLOY POWDER, THE IMPROVEMENT WHICH COMPRISES INCORPORATING ACICULAR FINE POWDERS WHICH ARE NOT THE SAME SUBSTANCE AS THE FERROMAGNETIC ALLOY INTO SAID AQUEOUS SOLUTION UPON WHICH SAID FERROMAGNETIC ALLOY PRECIPITATES, SAID FERROMAGNETIC ALLOY POWDER CONSISTING ESSENTIALLY OF SAID ACICULAR FINE POWDER HAVING LAYERED THEREAROUND SAID FERROMAGNETIC ALLOY.
Claim 3
Dependent Claim
30 words
The process of claim 1, wherein said process additionally comprises subjecting said aqueous solution to the action of a magnetic field or tHe effects of ultrasonic waves during said reduction.
Claim 4
Dependent Claim
32 words
The process of claim 1, wherein said aqueous solution additionally contains a minor amount of a rare earth element ion or an ion of aluminum, sulfur, chromium, manganese, iron, copper or zinc.
Claim 5
Dependent Claim
40 words
The process of claim 3, wherein said rare earth element ion or said ion of aluminum, sulphur, chromium, manganese, iron, copper or zinc is present in an amount sufficient to improve the coercive force of the resulting ferromagnetic alloy powder.
Claim 6
Dependent Claim
29 words
The process of claim 1, wherein said acicular fine powder has an average particle size of less than 0.3 Mu in length and less than 0.03 Mu in width.
Claim 7
Dependent Claim
27 words
The process of claim 1, wherein said acicular fine powder is diatomaceous earth, goethite lepidocrocite, gamma -Fe2O3, magnetite, CrO2, copper phthalocyanine, acicular ZnO, V2O5 or Attapulgus clay.
Claim 8
Dependent Claim
15 words
The process of claim 1, wherein said aqueous solution has a pH higher than 5.
Claim 9
Dependent Claim
28 words
The process of claim 1, wherein said aqueous solution has a pH of from 8 to 12 and said reducing is at a temperature of 70* to 95*C.
Claim 10
Dependent Claim
14 words
The process of claim 1, wherein said acicular fine powder is a non-magnetic material.
Claim 11
Dependent Claim
14 words
The process of claim 1, wherein said acicular fine powder is a ferromagnetic material.
Claim 12
Dependent Claim
18 words
The process of claim 1 wherein said ferromagnetic alloy powder has a length of 0.1 to 1 micron.
Claim 13
Dependent Claim
16 words
The process of claim 11, wherein said ferromagnetic alloy powder has a length/width ratio of 3:1.
Claim 14
Dependent Claim
19 words
The process of claim 1, wherein said ferromagnetic alloy powder is precipitated from said aqueous solution, washed and dried.
Claim 15
Dependent Claim
11 words
The process of claim 13 consisting essentially of the recited steps.
Claim 16
Dependent Claim
21 words
The process of claim 1, wherein the amount of metal present in said aqueous solution is from 0.5 to 20 g/l.
Claim 17
Dependent Claim
18 words
The process of claim 1, wherein said ferromagnetic alloy contains about 10 percent by weight or less phosphorous.
Claim 18
Dependent Claim
28 words
The process of claim 1, wherein the surface of the acicular fine powder is activated with a noble metal, the ferromagnetic alloy being precipitated thereon in layer form.
Claim 19
Dependent Claim
20 words
The process of claim 17, wherein the noble metal is selected from the group consisting of palladium, gold and silver.
Claim 20
Dependent Claim
19 words
The process of claim 17, wherein said noble metal is added to said aqueous solution in the chloride form.
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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 |