Patent US4305753A successfully refreshed from Google Patents.
US4305753A
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US
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Process for producing ferromagnetic metallic particles
Assignee: MAGNOX Inc
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Filing: 1980-07-31
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Granted: 1981-12-15
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Expires: 2000-07-31
Abstract
Abstract Described is an improved process for producing acicular ferromagnetic metallic particles by the reduction of acicular particles of iron oxide or iron oxide hydrate with a gaseous reducing agent. More specifically, the process concerns the improvement wherein the iron oxide or iron oxide hydrate particles are treated with a specified amount of a phosphorus compound and a compound of cobalt, nickel and/or copper prior to the reduction step.
Inventors
- 👤 James E. French
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:43
CPC Classifications
B; B22; B22F; B22F9/00; B22F9/16; B22F9/18; B22F9/20; B22F9/22; B22F1/00; B22F1/18; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/061; H01F1/065
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
119 words
In the process for producing acicular ferromagnetic metallic particles suitable for magnetic recording media by reducing acicular particles of iron oxide or iron oxide hydrate with a gaseous reducing agent, the improvement which comprises treating said iron oxide or iron oxide hydrate particles prior to the reducing step with a water-soluble phosphorus-containing compound and with at least one compound of a metal selected from the group consisting of cobalt, nickel and copper under conditions to provide on the surface of the oxide particles a coating containing, based on iron, from 0.1 to 5 atomic % of phosphorus and at least 0.1 atomic % of said metal, the atomic ratio of said metal to phosphorus ranging from 0.5:1 to 10:1.
Claim 2
Dependent Claim
119 words
In the process for producing acicular ferromagnetic metallic particles suitable for magnetic recording media by reducing acicular particles of iron oxide or iron oxide hydrate with a gaseous reducing agent, the improvement which comprises treating said iron oxide or iron oxide hydrate particles prior to the reducing step with a water-soluble phosphorus-containing compound and with at least one compound of a metal selected from the group consisting of cobalt, nickel and copper under conditions to provide on the surface of the oxide particles a coating containing, based on iron, from 0.1 to 5 atomic % of phosphorus and at least 0.1 atomic % of said metal, the atomic ratio of said metal to phosphorus ranging from 0.5:1 to 10:1.
Claim 3
Dependent Claim
13 words
The process of claim 1 in which the phosphorus compound is phosphoric acid.
Claim 4
Dependent Claim
17 words
The process of claim 2 in which the metal compound is a water-soluble salt, oxide or hydroxide.
Claim 5
Dependent Claim
12 words
The process of claim 3 in which the reducing agent is hydrogen.
Claim 6
Dependent Claim
17 words
The process of claim 4 in which a zinc compound is also present during the treating step.
Claim 7
Dependent Claim
13 words
The process of claim 5 in which the zinc compound is zinc oxide.
Claim 8
Dependent Claim
25 words
The process of claim 4 or 6 in which the treated particles are dehydrated at a temperature of 500° to 700° C. prior to reduction.
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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) | 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 |