US4165232A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacture of ferromagnetic metal particles essentially consisting of iron
Assignee: BASF SE
•
Filing: 1978-09-15
•
Granted: 1979-08-21
•
Expires: 1998-09-15
Abstract
Abstract A process for the manufacture of acicular ferromagnetic metal particles which essentially consist of iron and carry, on their surface, from 0.02 to 0.6% by weight of boron in the form of a borate, by reducing an acicular iron oxide with a gaseous reducing agent at from 250° to 500° C., wherein a compound selected from the group comprising boron oxyacids and their inorganic salts is precipitated on the said iron oxide before reduction.
Inventors
- 👤 Christof Jaeckh
- 👤 Werner Steck
- 👤 Rudolf Brodt
- 👤 Manfred Ohlinger
- 👤 Werner Loeser
- 👤 Eberhard Koester
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:04
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/065; H01F1/061; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
112 words
A method of preparing acicular ferromagnetic metal particles consisting essentially of iron and suitable for magnetic recording, said particles being modified at the surface with 0.02 to 0.6% by weight of boron as borate, by reducing a finely divided acicular iron compound selected from the group consisting of iron oxide and iron oxide hydrate with a gaseous reducing agent at a temperature of from 250° to 500° C., wherein there are deposited on said iron oxide or iron oxide hydrate, prior to reduction, a substance selected from the group consisting of oxyacids of boron and their inorganic salts in such an amount that 0.01 to 1% by weight of boron is present.
Claim 2
Independent Claim
112 words
A method of preparing acicular ferromagnetic metal particles consisting essentially of iron and suitable for magnetic recording, said particles being modified at the surface with 0.02 to 0.6% by weight of boron as borate, by reducing a finely divided acicular iron compound selected from the group consisting of iron oxide and iron oxide hydrate with a gaseous reducing agent at a temperature of from 250° to 500° C., wherein there are deposited on said iron oxide or iron oxide hydrate, prior to reduction, a substance selected from the group consisting of oxyacids of boron and their inorganic salts in such an amount that 0.01 to 1% by weight of boron is present.
Claim 3
Independent Claim
201 words
A method of preparing acicular ferromagnetic metal particles consisting essentially of iron and suitable for magnetic recording, said particles being modified at the surface with 0.02 to 0.6% by weight of boron as borate with 0.1 to 0.7% by weight of phosphorus as phosphate and with 0.02 to 0.2% by weight of carbon, by reducing a finely divided acicular iron compound selected from the group consisting of iron oxide and iron oxide hydrate with a gaseous reducing agent at a temperature of from 250° to 500° C., wherein there are deposited on said iron oxide or iron oxide hydrate, prior to reduction (a) a substance selected from the group consisting of oxyacids of boron and their inorganic salts in such an amount that 0.01 to 1% by weight of boron is present, (b) a hydrolysis-resistant substance selected from the group consisting of oxyacids of phosphorus, and their inorganic salts in such an amount that 0.2 to 2% by weight of phosphorus is present, and (c) a compound selected from the group consisting of aliphatic monobasic, dibasic and tribasic carboxylic acids of from 1 to 6 carbon atoms in such an amount that 0.1 to 1.2% by weight of carbon is present.
Claim 4
Independent Claim
201 words
A method of preparing acicular ferromagnetic metal particles consisting essentially of iron and suitable for magnetic recording, said particles being modified at the surface with 0.02 to 0.6% by weight of boron as borate with 0.1 to 0.7% by weight of phosphorus as phosphate and with 0.02 to 0.2% by weight of carbon, by reducing a finely divided acicular iron compound selected from the group consisting of iron oxide and iron oxide hydrate with a gaseous reducing agent at a temperature of from 250° to 500° C., wherein there are deposited on said iron oxide or iron oxide hydrate, prior to reduction (a) a substance selected from the group consisting of oxyacids of boron and their inorganic salts in such an amount that 0.01 to 1% by weight of boron is present, (b) a hydrolysis-resistant substance selected from the group consisting of oxyacids of phosphorus, and their inorganic salts in such an amount that 0.2 to 2% by weight of phosphorus is present, and (c) a compound selected from the group consisting of aliphatic monobasic, dibasic and tribasic carboxylic acids of from 1 to 6 carbon atoms in such an amount that 0.1 to 1.2% by weight of carbon is present.
References Cited (Backward Citations)
US2974104A
Cited
US3652334A
Cited
DE1902270A1
Cited
DE1907691A1
Cited
DE2014500A1
Cited
JPS4716052U
Cited
US3902888A
Cited
US4069367A
Cited
US3837839A
Cited
DE2212934A1
Cited
US3966510A
Cited
US4096316A
Cited
US4067755A
Cited
US4050962A
Cited
US4069073A
Cited
US4101311A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-08-20 | 1983-02-19 | 1983-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-08-20 | 1987-02-19 | 1987-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-08-20 | 1991-02-19 | 1991-08-21 | $7700.00 | Window Closed / Lapsed |