US2807856A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacture of silicon carbide varistors
Assignee: AT&T Inc
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Filing: 1953-07-23
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Granted: 1957-10-01
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Expires: 1973-07-23
Abstract
No abstract record available.
Inventors
- 👤 Carl J Frosch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:14
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/10; H01C7/105; H01C7/118
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
113 words
THE METHOD OF FORMING SILICON CARBIDE VARISTORS FROM UNREFINED SILICON CARBIDE CHUNKS DERIVED FROM FURNACE INGOTS, WHICH METHOD COMPRISES CRUSHING THE SILICON CARBIDE UNTIL THE PARTICLE SIZE HAS BEEN SUFFICIENTLY REDUCED THAT AT LEAST 20 PERCENT BY WEIGHT, BUT NOT ALL, WILL PASS A SCREEN HAVING OPENINGS OF ABOUT 30 MILS, SEPARATING THE SILICON CARBIDE FRACTION CAPABLE OF PASSING THROUGH SAID SCREEN FROM THE LARGER PARTICLED FRACTION, CRUSHING AT LEAST A PORTION OF SAID LARGER PARTICLED FRACTION TO A SMALLER PARTICLE SIZE, AND FORMING SAID LAST CRUSHED MATERIAL INTO VARISTORS, IN WHICH METHOD THE UNREFINED SILICON CARBIDE BEING CRUSHED IS SUCH THAT IT IS SUBSTANTIALLY INDENTICAL IN CHEMICAL COMPOSITION WITH THE CRUSHED PRODUCT.
Claim 2
Independent Claim
113 words
THE METHOD OF FORMING SILICON CARBIDE VARISTORS FROM UNREFINED SILICON CARBIDE CHUNKS DERIVED FROM FURNACE INGOTS, WHICH METHOD COMPRISES CRUSHING THE SILICON CARBIDE UNTIL THE PARTICLE SIZE HAS BEEN SUFFICIENTLY REDUCED THAT AT LEAST 20 PERCENT BY WEIGHT, BUT NOT ALL, WILL PASS A SCREEN HAVING OPENINGS OF ABOUT 30 MILS, SEPARATING THE SILICON CARBIDE FRACTION CAPABLE OF PASSING THROUGH SAID SCREEN FROM THE LARGER PARTICLED FRACTION, CRUSHING AT LEAST A PORTION OF SAID LARGER PARTICLED FRACTION TO A SMALLER PARTICLE SIZE, AND FORMING SAID LAST CRUSHED MATERIAL INTO VARISTORS, IN WHICH METHOD THE UNREFINED SILICON CARBIDE BEING CRUSHED IS SUCH THAT IT IS SUBSTANTIALLY INDENTICAL IN CHEMICAL COMPOSITION WITH THE CRUSHED PRODUCT.
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) | 1960-09-30 | 1961-04-01 | 1961-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-09-30 | 1965-04-01 | 1965-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-09-30 | 1969-04-01 | 1969-10-01 | $7700.00 | Window Closed / Lapsed |