US4493779A
Expired / Lapsed
US
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Process for the preparation of ferrite magnetic particulate for magnetic recording
Assignee: Fujifilm Holdings Corp
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Filing: 1984-02-14
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Granted: 1985-01-15
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Expires: 2004-02-14
Abstract
Abstract A process for the preparation of a ferrite magnetic particulate for magnetic recording which comprises steps of: (1) melting a starting material mixture containing a basic component for hexagonal ferrite, a coercive force-reducing component and a glass-forming component; (2) rapidly cooling the resulting molten mixture to obtain an amorphous material; (3) heat-treating said amorphous material to form ferrite crystals; and (4) removing components other than the ferrite crystals from the material resulting from said heat-treatment: characterized in that said starting material mixture contains a glass-forming component comprising a B 2 O 3 component and a SiO 2 component in which the amount of said SiO 2 component has a value (in terms of SiO 2 ) 0.05 to 0.8, the value being represented by a molar ratio of SiO 2 /(B 2 O 3 +SiO 2 ).
Inventors
- 👤 Kouzi Kamiyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:12
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; G11B5/84
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
94 words
A process for the preparation of a hexagonal ferrite magnetic particulate for magnetic recording having the formula RFe 12-2x M x M 1 x O 19 wherein R is at least one metal atom selected from the group consisting of barium, strontium and lead, M is at least one divalent metal atom selected from the group consisting of cobalt, nickel and zinc, M 1 is at least one tetravalent metal atom selected from the group consisting of titanium, zirconium and hafnium, and x is a number from 0.6 to 1.0 which comprises steps of:
Claim 2
Dependent Claim
94 words
A process for the preparation of a hexagonal ferrite magnetic particulate for magnetic recording having the formula RFe 12-2x M x M 1 x O 19 wherein R is at least one metal atom selected from the group consisting of barium, strontium and lead, M is at least one divalent metal atom selected from the group consisting of cobalt, nickel and zinc, M 1 is at least one tetravalent metal atom selected from the group consisting of titanium, zirconium and hafnium, and x is a number from 0.6 to 1.0 which comprises steps of:
Claim 3
Dependent Claim
17 words
(1) melting a starting material mixture containing basic components for said hexagonal ferrite, and a glass-forming component,
Claim 4
Dependent Claim
17 words
(1) melting a starting material mixture containing basic components for said hexagonal ferrite, and a glass-forming component,
Claim 5
Dependent Claim
12 words
(2) rapidly cooling the resulting molten mixture to obtain an amorphous material,
Claim 6
Dependent Claim
12 words
(2) rapidly cooling the resulting molten mixture to obtain an amorphous material,
Claim 7
Dependent Claim
10 words
(3) heat-treating said amorphous material to form ferrite crystals, and
Claim 8
Dependent Claim
10 words
(3) heat-treating said amorphous material to form ferrite crystals, and
Claim 9
Dependent Claim
80 words
(4) removing components other than the ferrite crystals from the materials resulting from said heat-treatment; characterized in that said starting material mixture contains a glass-forming component comprising a B 2 O 3 component and a SiO 2 component in which the molar ratio of SiO 2 /(B 2 O 3 +SiO 2 ) is, 0.05 to 0.8, said ferrite having a higher saturation magnetization than the ferrite of the same particle size prepared as above absent the SiO 2 component.
Claim 10
Dependent Claim
80 words
(4) removing components other than the ferrite crystals from the materials resulting from said heat-treatment; characterized in that said starting material mixture contains a glass-forming component comprising a B 2 O 3 component and a SiO 2 component in which the molar ratio of SiO 2 /(B 2 O 3 +SiO 2 ) is, 0.05 to 0.8, said ferrite having a higher saturation magnetization than the ferrite of the same particle size prepared as above absent the SiO 2 component.
Claim 11
Dependent Claim
97 words
The process for the preparation of a ferrite magnetic particulate as claimed in claim 1, wherein said starting material mixture contains each component constituting said mixture in such an amount in terms of the oxide that the amount of B 2 O 3 +SiO 2 is from 20 to 40 molar %, that of RO is from 25 to 50 molar %, that of Fe 2 O 3 is from 20 to 50 molar %, that of MO is from 2 to 10 molar %, and that of M'O 2 is from 2 to 10 molar %.
Claim 12
Dependent Claim
38 words
The process for the preparation of a ferrite magnetic particulate as claimed in claim 1, wherein the molar ratio of SiO 2 /(B 2 O 3 +SiO 2 ) is within a range of from 0.1 to 0.5.
References Cited (Backward Citations)
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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) | 1988-01-15 | 1988-07-16 | 1989-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-15 | 1992-07-16 | 1993-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-15 | 1996-07-16 | 1997-01-15 | $7700.00 | Window Closed / Lapsed |