Patent US4497672A successfully refreshed from Google Patents.
US4497672A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the preparation of a rare earth-cobalt based permanent magnet
Assignee: Shin-Etsu Chemical Co Ltd
•
Filing: 1983-04-04
•
Granted: 1985-02-05
•
Expires: 2003-04-04
Abstract
Abstract The permanet magnet composed of a rare earth element, e.g. samarium, and cobalt together with iron, copper and some other additive elements and prepared according to the inventive method has a high coercive force and excellent squareness of the magnetic hysteresis loop despite the relatively low content of copper which has been considered to be indispensable for obtaining a high coercive force. The characteristic feature of the inventive method consists in the aging treatment of the sintered body of the alloy powder of a specified composition undertaken in two or more steps, each being carried out by continuously cooling the sintered body within a specified temperature range at a specified cooling velocity.
Inventors
- 👤 Yoshio Tawara
- 👤 Ken Ohashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:47
CPC Classifications
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: 6
Claim 1
Independent Claim
213 words
A method for the preparation of a rare earth-cobalt based permanent magnet which comprises the steps of: (a) sintering a shaped body of an alloy powder composed of from 22 to 28% by weight of at least one rare earth element, from 10 to 30% by weight of iron, form 2 to 10% by weight of copper and from 0.1 to 5% by weight of at least one additive element selected from the group consisting of zirconium, titanium, manganese, tantalum, hafnium, chromium, silicon, tungsten and vanadium, the balance being cobalt, into a sintered body; (b) subjecting the sintered body to a primary aging treatment by heating at a temperature in the range from 600° to 850° C. followed by a first continuous cooling of the sintered body down to a temperature in the range from 300° to 400° C. at a cooling velocity in the range from 0.5° to 3.0° C./minute; and (c) subjecting the sintered body after the step (b) to a secondary aging treatment by heating at a temperature in the range from 700° to 900° C. followed by a second continuous cooling of the sintered body down to a temperature in the range from 300° to 500° C. at a cooling velocity in the range from 0.1 to 5.0° C./minute.
Claim 2
Independent Claim
213 words
A method for the preparation of a rare earth-cobalt based permanent magnet which comprises the steps of: (a) sintering a shaped body of an alloy powder composed of from 22 to 28% by weight of at least one rare earth element, from 10 to 30% by weight of iron, form 2 to 10% by weight of copper and from 0.1 to 5% by weight of at least one additive element selected from the group consisting of zirconium, titanium, manganese, tantalum, hafnium, chromium, silicon, tungsten and vanadium, the balance being cobalt, into a sintered body; (b) subjecting the sintered body to a primary aging treatment by heating at a temperature in the range from 600° to 850° C. followed by a first continuous cooling of the sintered body down to a temperature in the range from 300° to 400° C. at a cooling velocity in the range from 0.5° to 3.0° C./minute; and (c) subjecting the sintered body after the step (b) to a secondary aging treatment by heating at a temperature in the range from 700° to 900° C. followed by a second continuous cooling of the sintered body down to a temperature in the range from 300° to 500° C. at a cooling velocity in the range from 0.1 to 5.0° C./minute.
Claim 3
Dependent Claim
56 words
The method as claimed in claim 1 wherein the starting temperature of cooling-down in the step (c) is a temperature in the range between the same temperature as the starting temperature of the cooling-down in the step (b) and a temperature higher by 150° C. than the starting temperature of the cooling-down in the step (b).
Claim 4
Dependent Claim
40 words
The method as claimed in claim 1 wherein the velocity of temperature elevation from the lowermost temperature after the cooling-down in the step (b) to the starting temperature of the cooling-down in the step (c) does not exceed 20° C./minute.
Claim 5
Dependent Claim
66 words
The method as claimed in claim 1 wherein the sintered body after the step (c) is further subjected to a tertiary aging treatment by heating at a temperature in the range from 700° to 900° C. followed by a third continuous cooling down to a temperature in the range from 300° to 500° C. at a cooling velocity in the range from 0.1° to 5.0° C./minute.
Claim 6
Dependent Claim
67 words
The method as claimed in claim 4 wherein the sintered body after the tertiary aging treatment is further subjected to a quaternary aging treatment by heating at a temperature in the range from 700° to 900° C. followed by a fourth continuous cooling down to a temperature in the range from 300° to 500° C. at a cooling velocity in the range from 0.1° to 5.0° C./minute.
References Cited (Backward Citations)
US3998669A
Cited
US4210471A
Cited
JPS5562706A
Cited
JPS56156735A
Cited
US4276097A
Cited
JPS57100705A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-02-05 | 1988-08-06 | 1989-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-05 | 1992-08-06 | 1993-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-05 | 1996-08-06 | 1997-02-05 | $7700.00 | Window Closed / Lapsed |