Patent US3981726A successfully refreshed from Google Patents.
US3981726A
Expired / Lapsed
US
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Electrical contact materials
Assignee: Schneider Electric USA Inc
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Filing: 1975-06-13
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Granted: 1976-09-21
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Expires: 1995-06-13
Abstract
Abstract An electrical contact material which consists of a mixture of silver, 5 to 50 weight per cent of copper and 2 to 20 weight per cent of lanthanum, strontium chromite of formula La1-xSrxCrO3, where the values of x lie between 0 and 1.0, formed as a hard, chemically inert, non-metallic phase of high electrical conductivity both within the bulk of, and at the surface of, the contact material. Methods of producing the electrical contact materials utilizing powder metallurgical techniques are outlined.
Inventors
- 👤 Peter Douglas
- 👤 David John Pedder
- 👤 Peter John Swallow
- 👤 Terrence Ardern Davies
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:54
CPC Classifications
H; H01; H01H; H01H1/00; H01H1/02; H01H1/021; H01H1/023
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
129 words
A method of producing an electrical contact material including the steps of providing irregular silver powder having a powder particle size of not greater than approximately 350 mesh; providing irregular copper powder having a powder particle size of not greater than approximately 350 mesh; providing lanthanum strontium chromite powder of formula La 1-x Sr x CrO 3 , where the values lie between 0 and 1.0, and having a powder particle size of not greater than approximately 10 microns; mixing the powders together to provide a fine, evenly dispersed mixture containing 5 to 50 weight per cent of copper, 2 to 20 weight per cent of La 1-x Sr x CrO 3 and the remainder silver; compacting the powder mixture into a desired shape; and sintering the compacted shape.
Claim 2
Independent Claim
129 words
A method of producing an electrical contact material including the steps of providing irregular silver powder having a powder particle size of not greater than approximately 350 mesh; providing irregular copper powder having a powder particle size of not greater than approximately 350 mesh; providing lanthanum strontium chromite powder of formula La 1-x Sr x CrO 3 , where the values lie between 0 and 1.0, and having a powder particle size of not greater than approximately 10 microns; mixing the powders together to provide a fine, evenly dispersed mixture containing 5 to 50 weight per cent of copper, 2 to 20 weight per cent of La 1-x Sr x CrO 3 and the remainder silver; compacting the powder mixture into a desired shape; and sintering the compacted shape.
Claim 3
Dependent Claim
65 words
A method as claimed in claim 1 wherein the provision of the La 1-x Sr x CrO 3 powder includes the steps of mixing La, Sr and Cr nitrates in stoichiometric proportions; spray decomposing the mixed nitrate solution to provide a mixed oxide powder; sintering the oxide powder in air; milling the sintered powder under acetone; and washing the milled powder in dilute hydrochloric acid.
Claim 4
Dependent Claim
24 words
A method as claimed in claim 1 wherein the lanthanum, strontium chromite is of formula La 0 .7 Sr 0 .3 CrO 3 .
Claim 5
Dependent Claim
24 words
A method as claimed in claim 2 wherein the lanthanum, strontium chromite is of formula La 0 .7 Sr 0 .3 CrO 3 .
Claim 6
Dependent Claim
27 words
A method as claimed in claim 4 wherein the sintering of the mixed oxide powder is effected for approximately 1/2 hour at a temperature of approximately 1.250°C.
Claim 7
Dependent Claim
19 words
A method as claimed in claim 4 wherein the milling of the sintered powder is effected for 96 hours.
Claim 8
Dependent Claim
37 words
A method as claimed in claim 3 wherein the sintering of the powder compact is effected in an atmosphere of 3% hydrogen/97% nitrogen gas mixture at a temperature of 750°C for a period of approximately 1 hour.
Claim 9
Dependent Claim
25 words
A method as claimed in claim 1 wherein the compacting of the powder is effected at a pressure of approximately 20 tons per square inch.
Claim 10
Dependent Claim
17 words
A method as claimed in claim 1 wherein the powder mixing is effected by dry tumble milling.
Claim 11
Dependent Claim
21 words
A method as claimed in claim 1 which includes the step of coining the sintered compacts to increase the density thereof.
Claim 12
Dependent Claim
22 words
A method as claimed in claim 10 wherein the coining is effected at a pressure of approximately 50 tons per square inch.
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) | 1979-09-21 | 1980-03-22 | 1980-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-21 | 1984-03-22 | 1984-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-21 | 1988-03-22 | 1988-09-21 | $7700.00 | Window Closed / Lapsed |