Patent US4042535A successfully refreshed from Google Patents.
US4042535A
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Metal oxide varistor with improved electrical properties
Assignee: General Electric Co
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Filing: 1975-09-25
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Granted: 1977-08-16
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Expires: 1995-09-25
Abstract
Abstract Disclosed is a metal oxide varistor body and a method for manufacturing the same. Conventional manufacturing techniques through sintering are utilized on any metal oxide varistor formulation which includes bismuth oxide. Following sintering, the devices are heat treated at a temperature between 750° C and 1200° C for a time in excess of about 10 hours to cause the bismuth oxide to substantially completely convert to a body centered cubic phase. The presence of the body centered cubic bismuth oxide increases the alpha of the devices and substantially lowers the leakage current.
Inventors
- 👤 John E. May
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:10
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/10; H01C7/105; H01C7/108; H01C7/112
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
65 words
A metal oxide varistor body comprising a plurality of grains which consist primarily of zinc oxide base material and are separated by a cellular intergranular region which consists primarily of a plurality of preselected additives wherein at least one of said additives is bismuth oxide, said varistor being characterized by a relatively high percentage of said bismuth oxide in being a body centered cubic phase.
Claim 2
Dependent Claim
65 words
A metal oxide varistor body comprising a plurality of grains which consist primarily of zinc oxide base material and are separated by a cellular intergranular region which consists primarily of a plurality of preselected additives wherein at least one of said additives is bismuth oxide, said varistor being characterized by a relatively high percentage of said bismuth oxide in being a body centered cubic phase.
Claim 3
Dependent Claim
20 words
A varistor according to claim 1 wherein substantially all of said bismuth oxide is in the body centered cubic phase.
Claim 4
Dependent Claim
29 words
A varistor according to claim 2 wherein said varistor is further characterized by a higher alpha and lower leakage current than varistors without the body centered cubic bismuth oxide.
Claim 5
Dependent Claim
28 words
A varistor according to claim 3 wherein said additives further comprise at least one member of the group consisting of manganese, cobalt, antimony, tin, barium, boron and titanium.
Claim 6
Dependent Claim
23 words
A varistor according to claim 1 wherein the body centered cubic bismuth oxide coats a substantial portion of the surface of said grains.
Claim 7
Dependent Claim
20 words
A varistor according to claim 5 wherein substantially all of said bismuth oxide is in the body centered cubic phase.
Claim 8
Dependent Claim
29 words
A varistor according to claim 6 wherein said varistor is further characterized by a higher alpha and lower leakage current than varistors without the body centered cubic bismuth oxide.
Claim 9
Dependent Claim
28 words
A varistor according to claim 7 wherein said additives further comprise at least one member of the group consisting of manganese, cobalt, antimony, tin, barium, boron and titanium.
References Cited (Backward Citations)
US3663458A
Cited
US3699058A
Cited
US3642664A
Cited
US3687871A
Cited
US3836483A
Cited
US3872582A
Cited
US3903226A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-15 | 1981-02-14 | 1981-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-15 | 1985-02-14 | 1985-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-15 | 1989-02-14 | 1989-08-16 | $7700.00 | Window Closed / Lapsed |