US4063971A
Expired / Lapsed
US
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Method of increasing the coercive force of pulverized rare earth-cobalt alloys
Assignee: Evonik Operations GmbH
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Filing: 1971-02-18
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Granted: 1977-12-20
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Expires: 1991-02-18
Abstract
Abstract The coercive force of pulverized selected rare earth-cobalt alloys is increased or maintained at least at its initial value by depositing tin on the surface of the alloy particles and subjecting the particles to a heat treatment so as to cause diffusion of the tin into the particle structure.
Inventors
- 👤 Ekkehard Greinacher
- 👤 Klaus Reinhardt
- 👤 Karl Strnat
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:39
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/047; H01F1/053; H01F1/055; H01F1/0551; H01F1/0552; B; B22; B22F; B22F1/00; B22F1/17; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
53 words
A method of maintaining the coercive force of particulate rare earth-cobalt alloys at least at its initial value, which comprises enveloping substantially each alloy particle with a layer of solid tin and then heating the enveloped particles to a temperature sufficiently high so as to cause diffusion of tin into the particle structure.
Claim 2
Independent Claim
53 words
A method of maintaining the coercive force of particulate rare earth-cobalt alloys at least at its initial value, which comprises enveloping substantially each alloy particle with a layer of solid tin and then heating the enveloped particles to a temperature sufficiently high so as to cause diffusion of tin into the particle structure.
Claim 3
Dependent Claim
88 words
A method as claimed in claim 1, wherein the rare earth-cobalt alloy consists essentially of a rare earth component being composed of one or several of the elements Y, Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and another component being composed of cobalt alone or cobalt in mixture with at least one of Mn, Fe, Ni or Cu, the ratio of the rare earth component to the other component being about between 10-25 atomic percent to 75-90 atomic percent.
Claim 4
Independent Claim
142 words
A method of maintaining the coercive force of particulate rare earth-cobalt alloys at least at its initial value, said rare earth-cobalt alloy consisting essentially of a first rare earth component being composed of one or several of Y, Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu and a second component consisting essentially of cobalt alone or cobalt in mixture with at least one of Mn, Fe, Ni or Cu, the ratio of rare earth component to the second component being about 10-25 atomic percent to 75-90 atomic percent, which comprises depositing tin on the surface of the alloy particles to envelope substantially each particle with a substantially continuous layer of tin and then heating the enveloped alloy particles to a temperature sufficiently high so as to cause diffusion of tin into the particle structure.
Claim 5
Independent Claim
142 words
A method of maintaining the coercive force of particulate rare earth-cobalt alloys at least at its initial value, said rare earth-cobalt alloy consisting essentially of a first rare earth component being composed of one or several of Y, Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu and a second component consisting essentially of cobalt alone or cobalt in mixture with at least one of Mn, Fe, Ni or Cu, the ratio of rare earth component to the second component being about 10-25 atomic percent to 75-90 atomic percent, which comprises depositing tin on the surface of the alloy particles to envelope substantially each particle with a substantially continuous layer of tin and then heating the enveloped alloy particles to a temperature sufficiently high so as to cause diffusion of tin into the particle structure.
Claim 6
Dependent Claim
30 words
A method as claimed in claim 3, wherein said heating is effected so that tin diffuses into those strata of the alloy particles which are closest to the particle surface.
Claim 7
Dependent Claim
20 words
A method as claimed in claim 3, wherein the tin enveloped particles are heated to a temperature above 150° C.
Claim 8
Dependent Claim
34 words
A method as claimed in claim 3, wherein the amount of tin deposited on said particles is about between 0.1 to 5% by weight of tin calculated on the total weight of the alloy.
Claim 9
Dependent Claim
36 words
A method as claimed in claim 3, wherein said tin is deposited on said particles by mixing the alloy powder with a tin-mercury alloy and heating the mixture thus obtained until the mercury has been expelled.
Claim 10
Dependent Claim
48 words
A method as claimed in claim 7, wherein said heating is effected under vacuum conditions and at a temperature of above 200° C. whereby the heating results not only in the expulsion of mercury but also in the migration of tin into the surface strata of the particles.
Claim 11
Dependent Claim
25 words
A method as claimed in claim 3, wherein said heat treatment is combined with shaping said particulate tin enveloped alloy particles into a permanent magnet.
Claim 12
Dependent Claim
20 words
A method as claimed in claim 9, wherein magnetic field is applied to the alloy particles during the shaping procedure.
Claim 13
Dependent Claim
19 words
A method as claimed in claim 9, wherein the shaping is carried out in the presence of a binder.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-12-19 | 1981-06-20 | 1981-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-12-19 | 1985-06-20 | 1985-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-12-19 | 1989-06-20 | 1989-12-20 | $7700.00 | Window Closed / Lapsed |