US3960554A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Powdered metallurgical process for forming vacuum interrupter contacts
Assignee: Westinghouse Electric Corp
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Filing: 1974-06-03
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Granted: 1976-06-01
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Expires: 1994-06-03
Abstract
Abstract A powdered metallurgical procedure for forming chromium copper contacts used in vacuum interrupters, wherein by adding a small amount of copper powder to the difficult-to-press chromium powder, superior pressed properties are attained and a resulting chromium compact having higher green strength is produced. By practicing the teaching of this invention, vacuum interrupter contacts can be pressed to complex shapes. It is desirable to have a vacuum interrupter contact having an approximately 50% chromium composition. The low compacting pressure necessary to produce a 40% to 60% chromium powder concentrations yields a compact having a very low green strength which cannot be ejected from a die without falling apart; by adding a small amount of copper powder to the chromium powder before pressing a compact having a much higher green strength, which can be readily handled, is obtained. Using the disclosed process a press to shape contact having a variable density can be attained. This process can be used to produce a desirable chromium compact having a high density on the peripheral areas which decreases to a lower density in the center contact area.
Inventors
- 👤 Robert E. Gainer, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:28
CPC Classifications
H; H01; H01H; H01H1/00; H01H1/02; H01H1/0203; H01H1/0206; H01H11/00; H01H11/04; H01H11/048; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12014; Y10T428/1216
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
133 words
A method of forming a chromium copper contact for a vacuum circuit interrupter wherein the chromium content is between 40 to 60 weight percent comprising the steps of: blending a minor addition of copper powder with a chromium powder; pressing the blended powder in a die with a pressure of less than 20 tons per square inch to the shape desired, so that the desired chromium porosity is produced in the compact whereby the chromium content of the finished contact is between 40 to 60 weight percent; removing the pressed compact shape from the die; vacuum sintering for a predetermined time to form a porous chromium matrix which is preferably infiltrated with the minor addition of copper; and final sintering and fully infiltrating the chromium matrix with copper to fill the chromium matrix.
Claim 2
Independent Claim
133 words
A method of forming a chromium copper contact for a vacuum circuit interrupter wherein the chromium content is between 40 to 60 weight percent comprising the steps of: blending a minor addition of copper powder with a chromium powder; pressing the blended powder in a die with a pressure of less than 20 tons per square inch to the shape desired, so that the desired chromium porosity is produced in the compact whereby the chromium content of the finished contact is between 40 to 60 weight percent; removing the pressed compact shape from the die; vacuum sintering for a predetermined time to form a porous chromium matrix which is preferably infiltrated with the minor addition of copper; and final sintering and fully infiltrating the chromium matrix with copper to fill the chromium matrix.
Claim 3
Dependent Claim
36 words
A method of forming a chromium copper contact for a vacuum interrupter as claimed in claim 1 wherein: the blended minor addition of copper and chromium powder comprises less than 10% by weight of copper powder.
Claim 4
Independent Claim
83 words
A method of producing a chromium-copper contact for a vacuum circuit interrupter comprising the steps of: blending a predetermined amount of copper powder with a chromium powder; pressing the blended chromium copper powder in a die to a pressure sufficient to provide the desired chromium porosity in the compact to insure that the chromium content of the finished contact in between 40 to 60 weight percent; sintering the green compact to form a chromium matrix; and infiltrating the compact chromium matrix with copper.
Claim 5
Independent Claim
83 words
A method of producing a chromium-copper contact for a vacuum circuit interrupter comprising the steps of: blending a predetermined amount of copper powder with a chromium powder; pressing the blended chromium copper powder in a die to a pressure sufficient to provide the desired chromium porosity in the compact to insure that the chromium content of the finished contact in between 40 to 60 weight percent; sintering the green compact to form a chromium matrix; and infiltrating the compact chromium matrix with copper.
Claim 6
Dependent Claim
31 words
A method of producing a contact for a vacuum circuit interrupter as claimed in claim 3 including the step of machining the sintered compact to a desired shape before copper infiltration.
Claim 7
Dependent Claim
34 words
A method of producing a contact for a vacuum circuit interrupter as claimed in claim 3 wherein: the amount of copper powder blended with the chromium powder is less than 10 percent by weight.
Claim 8
Dependent Claim
35 words
A method of producing a contact for a vacuum circuit interrupter as claimed in claim 3 wherein: the blended chromium copper powder is pressed to a pressure of less than 20 tons per square inch.
Claim 9
Dependent Claim
50 words
The method of forming a chromium copper contact for a vacuum circuit interrupter as set forth in claim 1 wherein, the compacting pressure is controlled to vary the chromium matrix porosity in the pressed compact shape so that the chromium density in the final contact varies in a desired relationship.
References Cited (Backward Citations)
US2656595A
Cited
US2362007A
Cited
US2401221A
Cited
US2758229A
Cited
US2807542A
Cited
US3360348A
Cited
US3338687A
Cited
US3366463A
Cited
US3353931A
Cited
US3619170A
Cited
US3585342A
Cited
US3859087A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-06-01 | 1979-12-01 | 1980-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-01 | 1983-12-01 | 1984-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-01 | 1987-12-01 | 1988-06-01 | $7700.00 | Window Closed / Lapsed |