US4198443A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sinterless zinc oxide varistor devices
Assignee: General Electric Co
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Filing: 1978-05-26
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Granted: 1980-04-15
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Expires: 1998-05-26
Abstract
Abstract Sinterless zinc oxide varistor devices are prepared in one embodiment by flame spraying premixed zinc oxide and additive metal oxide powders onto a refractory substrate. The coated substrate is then treated by an abrasive removal process to form a trimmable resistor. A further embodiment comprises the use of a plasma spray process wherein carbonates and nitrates of the varistor constituents are oxidized in situ by entrainment within an oxygen gas stream and directing the plasma upon a rotating substrate. Ultra pure zinc oxide varistor devices having excellent electrical properties can be prepared in this manner.
Inventors
- 👤 John J. Pitha
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 08:29
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/453; B; B05; B05B; B05B13/00; B05B13/02; B05B13/0221; B05B13/0228; B05B7/00; B05B7/16; B05B7/22; B05B7/222; B05B7/226; C23; C23C; C23C4/00; C23C4/02; C23C4/04; C23C4/10; C23C4/11; C23C4/12; H; H01; H01C; H01C7/00; H01C7/10; H01C7/1006
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
87 words
A method for manufacturing sinterless zinc oxide varistor devices comprising the steps of: providing a mixture of zinc oxide powder and additive metal oxide powders; subjecting the mixture to a high temperature flame for heating and fusing the oxides; providing an oxygen containing gas stream for directing the oxide powders through the flame; directing the fused oxides upon the surface of an electrically insulating aluminum oxide substrate to form the varistor material on the substrate; and providing at least one metal electrode layer on the varistor material.
Claim 2
Independent Claim
87 words
A method for manufacturing sinterless zinc oxide varistor devices comprising the steps of: providing a mixture of zinc oxide powder and additive metal oxide powders; subjecting the mixture to a high temperature flame for heating and fusing the oxides; providing an oxygen containing gas stream for directing the oxide powders through the flame; directing the fused oxides upon the surface of an electrically insulating aluminum oxide substrate to form the varistor material on the substrate; and providing at least one metal electrode layer on the varistor material.
Claim 3
Dependent Claim
12 words
The method of claim 1 wherein the additive metal oxides include bismuth.
Claim 4
Dependent Claim
11 words
The method of claim 1 wherein the metal electrode comprises aluminum.
Claim 5
Dependent Claim
12 words
The method of claim 1 wherein the substrate comprises a tubular member.
Claim 6
Dependent Claim
23 words
The method of claim 1 including the step of removing a portion of the metal oxide coating to provide a trimmable non-linear resistor.
Claim 7
Dependent Claim
30 words
The method of claim 1 wherein the substrate comprises a planar surface and wherein the metal oxide layer has a region of reduced cross section for providing a fusible varistor.
Claim 8
Independent Claim
83 words
A method for forming high purity sinterless varistor materials comprising the steps of: providing zinc and bismuth chloride varistor precursor materials; entraining the chlorides in an oxygen containing gas stream; adding an inert gas to the oxygen containing gas stream; directing the entrained chlorides through a plasma torch for heating the chlorides to form zinc and bismuth oxide powders and fusing the powders; and directing the fused powders upon the surface of an electrically insulating aluminum oxide substrate to form a varistor body.
Claim 9
Independent Claim
83 words
A method for forming high purity sinterless varistor materials comprising the steps of: providing zinc and bismuth chloride varistor precursor materials; entraining the chlorides in an oxygen containing gas stream; adding an inert gas to the oxygen containing gas stream; directing the entrained chlorides through a plasma torch for heating the chlorides to form zinc and bismuth oxide powders and fusing the powders; and directing the fused powders upon the surface of an electrically insulating aluminum oxide substrate to form a varistor body.
Claim 10
Dependent Claim
22 words
The method of claim 7 including the step of rotating the substrate in order to generate a cylinder of the varistor material.
Claim 11
Independent Claim
107 words
A method of forming a sinterless zinc oxide varistor comprising the steps of: providing a tubular insulating aluminum oxide substrate; mixing a plurality of metal carbonates with zinc nitrates to form the varistor precursor mixture; introducing an air stream to the precursor mixture to entrain the mixture and to form a continuous stream of airborn particles; directing the entrained particles through a high temperature flame for fusing the particles upon the substrate; applying a layer of aluminum at both ends of the substrate to provide a pair of electrodes; and removing part of the oxide layer to form a thin spiral of oxide material around the substrate.
Claim 12
Independent Claim
107 words
A method of forming a sinterless zinc oxide varistor comprising the steps of: providing a tubular insulating aluminum oxide substrate; mixing a plurality of metal carbonates with zinc nitrates to form the varistor precursor mixture; introducing an air stream to the precursor mixture to entrain the mixture and to form a continuous stream of airborn particles; directing the entrained particles through a high temperature flame for fusing the particles upon the substrate; applying a layer of aluminum at both ends of the substrate to provide a pair of electrodes; and removing part of the oxide layer to form a thin spiral of oxide material around the substrate.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-15 | 1983-10-15 | 1984-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-15 | 1987-10-15 | 1988-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-15 | 1991-10-15 | 1992-04-15 | $7700.00 | Window Closed / Lapsed |