US4341648A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for manufacturing magnetic powder for high density magnetic recording
Assignee: Toshiba Corp
•
Filing: 1980-11-03
•
Granted: 1982-07-27
•
Expires: 2000-11-03
Abstract
Abstract A method for preparing a magnetic powder for high density magnetic recording includes melting a mixture containing the fundamental component of a hexagonal ferrite, a substituting component for reducing the coercive force, and a glass forming material. The resultant molten material is rapidly cooled to obtain an amorphous body which is then heat-treated to produce desired substituted type hexagonal ferrite particles in the glass matrix.
Inventors
- 👤 Osamu Kubo
- 👤 Tadashi Ido
- 👤 Tutomu Nomura
- 👤 Koichiro Inomata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:06
CPC Classifications
B; B82; B82Y; B82Y30/00; C; C01; C01G; C01G49/00; C01G49/0018; C01G49/0036; C01G49/009; C04; C04B; C04B35/00; C04B35/01; C04B35/26; C04B35/2683; C01P; C01P2002/00; C01P2002/50; C01P2002/52; C01P2002/54; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/54; C01P2004/60; C01P2004/62; C01P2004/64; C01P2006/00; C01P2006/42
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
195 words
A method for manufacturing a magnetic powder for high density magnetic recording having a particle size within the range of 0.01 to 0.3 microns, comprising: mixing, together with a glass forming substance, metal oxide or metal oxide precursor components of a substituted ferrite having the formula: AFe.sub.12-2x Co.sub.x M.sub.x O.sub.19 or AFe.sub.12-3/2x Co.sub.x M.sub.1/2x O.sub.19 wherein A is at least one element selected from the group consisting of barium, strontium, lead and calcium, M is at least one tetravalent element selected from the group consisting of titanium and germanium or at least one pentavalent element selected from the group consisting of vanadium, niobium, antimony and tantalum, and x is a value from 0.5 to 1.1; melting the mixture into a molten material; rapidly cooling the molten material to obtain an amorphous material; heat-treating the amorphous material in the range between 700° and 850° C. to precipitate a substituted hexagonal ferrite as mutually separated fine particles in the amorphous material; and separating the fine particles from the amorphous material wherein said metal oxide or metal oxide precursor components are mixed in an amount sufficient to provide, as said fine particles, a substituted ferrite of said formulation.
Claim 2
Independent Claim
195 words
A method for manufacturing a magnetic powder for high density magnetic recording having a particle size within the range of 0.01 to 0.3 microns, comprising: mixing, together with a glass forming substance, metal oxide or metal oxide precursor components of a substituted ferrite having the formula: AFe.sub.12-2x Co.sub.x M.sub.x O.sub.19 or AFe.sub.12-3/2x Co.sub.x M.sub.1/2x O.sub.19 wherein A is at least one element selected from the group consisting of barium, strontium, lead and calcium, M is at least one tetravalent element selected from the group consisting of titanium and germanium or at least one pentavalent element selected from the group consisting of vanadium, niobium, antimony and tantalum, and x is a value from 0.5 to 1.1; melting the mixture into a molten material; rapidly cooling the molten material to obtain an amorphous material; heat-treating the amorphous material in the range between 700° and 850° C. to precipitate a substituted hexagonal ferrite as mutually separated fine particles in the amorphous material; and separating the fine particles from the amorphous material wherein said metal oxide or metal oxide precursor components are mixed in an amount sufficient to provide, as said fine particles, a substituted ferrite of said formulation.
Claim 3
Dependent Claim
13 words
The method as claimed in claim 1, wherein M is a tetravalent metal.
Claim 4
Dependent Claim
23 words
The method as claimed in claim 2, wherein the molar ratio of Fe 2 O 3 :CoO:MO 2 is about 4.45:1:1 to 11:1:1.
Claim 5
Dependent Claim
11 words
The method as claimed in claim 3, wherein A is barium.
Claim 6
Dependent Claim
13 words
The method as claimed in claim 1, wherein M is a pentavalent metal.
Claim 7
Dependent Claim
24 words
The method as claimed in claim 5, wherein the molar ratio of Fe 2 O 3 :CoO:MO 2 .5 is about 9.4:2:1 to 22.50:2:1.
Claim 8
Dependent Claim
11 words
The method as claimed in claim 6, wherein A is barium.
Claim 9
Dependent Claim
27 words
The method as claimed in claim 6, wherein the glass forming substance is B 2 O 3 , P 2 O 5 , or SiO 2 .
Claim 10
Dependent Claim
18 words
The method as claimed in claim 8, wherein said glass forming material is B 2 O 3 .
Claim 11
Dependent Claim
16 words
The method as claimed in claim 8, wherein said glass forming substance further comprises barium oxide.
Claim 12
Dependent Claim
25 words
The method as claimed in claim 1, wherein said fine particles are separated from the amorphous material by dissolving the amorphous material with an acid.
Claim 13
Dependent Claim
25 words
The method as claimed in claim 1 or 9, wherein a heat treatment is performed at 700° to 850° C. for 2 hours or more.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-07-26 | 1986-01-25 | 1986-07-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-07-26 | 1990-01-25 | 1990-07-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-07-26 | 1994-01-25 | 1994-07-27 | $7700.00 | Window Closed / Lapsed |