US3936367A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing a layer of dark colored heat radiating insulating material for heaters of indirectly heated cathodes
Assignee: Nokia Deutschland GmbH
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Filing: 1974-12-18
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Granted: 1976-02-03
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Expires: 1994-12-18
Abstract
Abstract Heater for indirectly heated cathodes with a homogeneous dark colored insulating layer which is formed by introducing aluminum oxide, tungsten oxide and chromium oxide, all in powder form, into a coating bath and coating the heaters in a combined electrophoretic-electrolytic process by dipping them into the bath only once. Advantages: simplified production (only one coating process); improved heat radiation; short heating time; longer service life.
Inventors
- 👤 Eberhard Weiss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:35
CPC Classifications
H; H01; H01J; H01J9/00; H01J9/02; H01J9/04; C; C25; C25D; C25D13/00; C25D13/02
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
107 words
A method of producing a dark colored heat radiating layer of insulating material for heaters of indirectly heated cathodes, characterized in that aluminum-oxide powder is intimately mixed with tungsten-oxide powder and chromium-oxide powder, that a coating bath is prepared with said mixture and additions of aluminum nitrate, magnesium nitrate, ethanol and water, that the heaters dipped into said coating bath are coated electrophoretically with a porous, dark colored heat radiating layer of insulating material, with electrolysis taking place simultaneously, and that the heaters are then rinsed, in known manner, in a suitable liquid such as methanol, dried, and finally sintered in a nitrogen-hydrogen atmosphere at about 1,600°C.
Claim 2
Independent Claim
107 words
A method of producing a dark colored heat radiating layer of insulating material for heaters of indirectly heated cathodes, characterized in that aluminum-oxide powder is intimately mixed with tungsten-oxide powder and chromium-oxide powder, that a coating bath is prepared with said mixture and additions of aluminum nitrate, magnesium nitrate, ethanol and water, that the heaters dipped into said coating bath are coated electrophoretically with a porous, dark colored heat radiating layer of insulating material, with electrolysis taking place simultaneously, and that the heaters are then rinsed, in known manner, in a suitable liquid such as methanol, dried, and finally sintered in a nitrogen-hydrogen atmosphere at about 1,600°C.
Claim 3
Dependent Claim
36 words
The method according to claim 1, characterized in that the powdery mixture consists of about 86% by weight of aluminum oxide, about 10% by weight of tungsten oxide, and about 4% by weight of chromium oxide.
References Cited (Backward Citations)
US2734857A
Cited
GB1177489A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-02-02 | 1979-08-04 | 1980-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-02-02 | 1983-08-04 | 1984-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-02-02 | 1987-08-04 | 1988-02-03 | $7700.00 | Window Closed / Lapsed |