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Patent US4888068A successfully refreshed from Google Patents.
US4888068A
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US
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Process for manufacturing permanent magnet
Assignee: Proterial Ltd
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Filing: 1985-10-04
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Granted: 1989-12-19
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Expires: 2005-10-04
Abstract
Abstract A process for manufacturing a rare earth-iron-boron alloy permanent magnet by, after sintering, keeping the sintered alloy at temperatures of 750°-1000° C. for 0.2-5 hours, slowly cooling it at a cooling rate of 0.3°-5° C./min. to temperatures between room temperature and 600° C.; annealing it at temperatures of 550°-700° C. for 0.2-3 hours, and rapidly cooling it at a cooling rate of 20°-400° C./min. The permanent magnet contains a matrix, a B-rich phase and a Nd-rich phase. In grain boundaries of the matrix phases covered by bcc phases, thin, fine plates of the bcc phases projecting into the matrix phases are once increased by the first heat treatment and slow cooling and then eliminated by the annealing.
Inventors
- 👤 Masaaki Tokunaga
- 👤 Minoru Endoh
- 👤 Noriaki Meguro
- 👤 Shigeho Tanigawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:34
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/047; H01F1/053; H01F1/055; H01F1/057; H01F1/0571; H01F1/0575; H01F1/0577
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
118 words
A process for manufacturing a sintered body of a permanent magnet having an alloy composition represented by the general formula R(Fe.sub.1-x-y Co.sub.x B.sub.y)z wherein R represents Nd and/or Pr which may be partially substituted by one or more other rare earth elements, 0≦x≦0.5, 0.02≦y≦0.3 and 4≦z≦7.5, which comprises the steps of: (a) maintaining a sintered alloy body at temperatures of 750°-1000° C. for 0.2--5 hours after sintering; (b) cooling said sintered alloy body slowly at a cooling rate of 0.6°-2.0° C./min. to temperatures between room temperature and 600° C.; (c) annealing said sintered alloy boby at temperatures of 550°-700° C. for 0.2-3 hours; and (d) cooling said sintered alloy body rapidly at a cooling rate of 20°-400° C./min.
Claim 2
Dependent Claim
118 words
A process for manufacturing a sintered body of a permanent magnet having an alloy composition represented by the general formula R(Fe.sub.1-x-y Co.sub.x B.sub.y)z wherein R represents Nd and/or Pr which may be partially substituted by one or more other rare earth elements, 0≦x≦0.5, 0.02≦y≦0.3 and 4≦z≦7.5, which comprises the steps of: (a) maintaining a sintered alloy body at temperatures of 750°-1000° C. for 0.2--5 hours after sintering; (b) cooling said sintered alloy body slowly at a cooling rate of 0.6°-2.0° C./min. to temperatures between room temperature and 600° C.; (c) annealing said sintered alloy boby at temperatures of 550°-700° C. for 0.2-3 hours; and (d) cooling said sintered alloy body rapidly at a cooling rate of 20°-400° C./min.
Claim 3
Dependent Claim
26 words
The process for manufacturing a sintered body of a permanent magnet according to claim 1, wherein x i 0-0.3, y is 0.06-0.15 and z is 5-6.
Claim 4
Dependent Claim
27 words
The process for manufacturing a sintered body of a permanent magnet according to claim 1, wherein Step (d) is conducted in water, silicone oil or argon gas.
References Cited (Backward Citations)
JPS5946008A
Cited
JPS5964733A
Cited
JPS5989401A
Cited
US4597938A
Cited
JPS59219453A
Cited
US4601875A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-12-18 | 1993-06-19 | 1993-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-18 | 1997-06-19 | 1997-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-18 | 2001-06-19 | 2001-12-19 | $7700.00 | Window Closed / Lapsed |