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US3873379A
Expired / Lapsed
US
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Method of producing rare earth-cobalt permanent magnet using special cooling rates
Assignee: Proterial Ltd
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Filing: 1973-07-10
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Granted: 1975-03-25
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Expires: 1993-07-10
Abstract
Abstract A method of producing a rare earth-coabalt permanent magnet having high coercive force wherein powdery alloy containing rare earth elements and cobalt as principal component is compacted in magnetic field, the resulting green body is sintered at the temperature between 1,000* to 1,200*C, the sintered body is cooled from the above sintering temperature to quenching temperature in the range of 875* + OR - 50*C at a rate of 7*C/min. or slower rate, and then further cooled successively from the quenching temperatures to room temperature at a rate of 20*C/min. or faster rate.
Inventors
- 👤 Kazuo Yamakawa
- 👤 Tohru Oka
- 👤 Masaaki Tokunaga
- 👤 Takeshi Mizuhara
- 👤 Chitoshi Hagi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:41
CPC Classifications
B; B22; B22F; B22F3/00; B22F3/12; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/047; H01F1/053; H01F1/055; H01F1/0555; H01F1/0557
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
39 words
PREPARING A POWDERY ALLOY FROM ABOUT 55-70% BY WEIGHT OF COBALT AND ABOUT 30-45% BY WEIGHT OF AT LEAST ONE RARE EARTH ELEMENT, SELECTED FROM THE GROUP CONSISTING OF Y, LA, CE, PR, SM, ND, GD, HO, AND ER,
Claim 2
Dependent Claim
39 words
PREPARING A POWDERY ALLOY FROM ABOUT 55-70% BY WEIGHT OF COBALT AND ABOUT 30-45% BY WEIGHT OF AT LEAST ONE RARE EARTH ELEMENT, SELECTED FROM THE GROUP CONSISTING OF Y, LA, CE, PR, SM, ND, GD, HO, AND ER,
Claim 3
Independent Claim
50 words
A METHOD OF PRODUCING A PERMANENT MAGNET HAVING A RESIDUAL MAGNETIC FLUX DENSITY OF AT LEAST 8000 OEGAUSS, A NORMAL COERCIVE FORCE OF AT LEAST 8000 OERSTED, AN INTRINSIC COERCIVE FORCE OF AT LEAST 27,000 OERSTED AND MAXIMUM ENERGY PRODUCT OF AT LEAST 17.6X106 GAUSS OERSTED COMPRISING THE STEPS OF:
Claim 4
Independent Claim
50 words
A METHOD OF PRODUCING A PERMANENT MAGNET HAVING A RESIDUAL MAGNETIC FLUX DENSITY OF AT LEAST 8000 OEGAUSS, A NORMAL COERCIVE FORCE OF AT LEAST 8000 OERSTED, AN INTRINSIC COERCIVE FORCE OF AT LEAST 27,000 OERSTED AND MAXIMUM ENERGY PRODUCT OF AT LEAST 17.6X106 GAUSS OERSTED COMPRISING THE STEPS OF:
Claim 5
Dependent Claim
7 words
COMPACTING SAID POWDERY ALLOY IN AMAGNETIC FIELD,
Claim 6
Dependent Claim
7 words
COMPACTING SAID POWDERY ALLOY IN AMAGNETIC FIELD,
Claim 7
Dependent Claim
8 words
compacting said powdery alloy in a magnetic field,
Claim 8
Dependent Claim
8 words
compacting said powdery alloy in a magnetic field,
Claim 9
Dependent Claim
50 words
A method of producing a permanent magnet according to claim 1, wherein said sintered body is cooled from the sintering temperature to the quenching temperature at a rate no greater than 2*C/min and further cooled immediately from the quenching temperature to room temperature at a rate of at least 100*C/min.
Claim 10
Dependent Claim
11 words
sintering said compact at a temperature between 1,000* to 1, 200*C.,
Claim 11
Dependent Claim
11 words
sintering said compact at a temperature between 1,000* to 1, 200*C.,
Claim 12
Dependent Claim
50 words
A method of producing a permanent magnet according to claim 1, wherein said sintered body is cooled from the sintering temperature to the quenching temperature at a rate no greater than 0.1*C/min. and further cooled immediately from the quenching temperature to room temperature at a rate of at least 400*C/min.
Claim 13
Dependent Claim
10 words
SINTERING SAID COMPACT AT A TEMPERATURE BETWEEN 1,000* TO 1,200*C.,
Claim 14
Dependent Claim
10 words
SINTERING SAID COMPACT AT A TEMPERATURE BETWEEN 1,000* TO 1,200*C.,
Claim 15
Dependent Claim
27 words
COOLING SAID SINTERED BODY FROM SAID SINTERING TEMPERATURE TO A QUENCHING TEMPERATURE IN THE RANGE OF ABOUT 825* TO 925*C. AT ARATE NO GREATER THAN 7*C./MIN., AND
Claim 16
Dependent Claim
27 words
COOLING SAID SINTERED BODY FROM SAID SINTERING TEMPERATURE TO A QUENCHING TEMPERATURE IN THE RANGE OF ABOUT 825* TO 925*C. AT ARATE NO GREATER THAN 7*C./MIN., AND
Claim 17
Dependent Claim
21 words
A method of producing a permanent magnet according to claim 3, wherein samarium-cobalt powdery alloy is used as the powdery alloy.
Claim 18
Dependent Claim
28 words
cooling said sintered body from said sintering temperature to a quenching temperature in the range of about 825* to 925*C. at a rate no greater than 7*C./min., and
Claim 19
Dependent Claim
28 words
cooling said sintered body from said sintering temperature to a quenching temperature in the range of about 825* to 925*C. at a rate no greater than 7*C./min., and
Claim 20
Dependent Claim
19 words
cooling said sintered body immediately from said quenching temperature to room temperature at a rate of at least 20*C./min.
Claim 21
Dependent Claim
19 words
cooling said sintered body immediately from said quenching temperature to room temperature at a rate of at least 20*C./min.
Claim 22
Dependent Claim
21 words
A method of producing a permanent magnet according to claim 3, wherein samarium-praseodymium-cobalt pOwdery alloy is used as the powdery alloy.
Claim 23
Dependent Claim
18 words
COOLING SAID SINTERED BODY IMMEDIATEKY FROM SAID QUENCHIN TEMPERATURE TO ROOM TEMPERATURE AT ARATE OF AT LEAST 20*C./MIN.
Claim 24
Dependent Claim
18 words
COOLING SAID SINTERED BODY IMMEDIATEKY FROM SAID QUENCHIN TEMPERATURE TO ROOM TEMPERATURE AT ARATE OF AT LEAST 20*C./MIN.
Claim 25
Dependent Claim
61 words
A method of producing a permanent magnet according to claim 1, wherein said sintered body is cooled from the sintering temperature to a quenching temperature of between 850* to 900*C at a rate no greater than 0.1*C/min., and the body thus cooled is further cooled immediately from the quenching temperature to room temperature at a rate of 400*C/min. or faster rate.
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) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |