US4393328A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hot cathode, its production process and electron tube incorporating such a cathode
Assignee: Thales SA
•
Filing: 1980-11-05
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Granted: 1983-07-12
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Expires: 2000-11-05
Abstract
Abstract The hot cathode, according to the invention, is constituted by a fritted matrix 1 and a heating filament 4, said matrix being formed from a powder mixture 2 of tungsten and another high work function refractory metal and covered with a high work function refractory metal film 3. FIG. 3.
Inventors
- 👤 Arvind Shroff
- 👤 Pierre Palluel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:45
CPC Classifications
H; H01; H01J; H01J9/00; H01J9/02; H01J9/04; H01J1/00; H01J1/02; H01J1/13; H01J1/14; H01J23/00; H01J23/02; H01J23/04
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
143 words
A process for producing a cathode formed from a matrix of a fritted powder metal impregnated with a barium compound, and a heating filament associated with said matrix, wherein the matrix is formed from a mixture of two metals, tungsten and another high work function refractory metal, and wherein the matrix is covered with a high work function refractory metal film, comprising the following successive stages: (a) mixing powders of tungsten and another high work function refractory metal (b) pressing the mixture between 7 and 10 t/cm 2 (c) prefritting under hydrogen at between 1100° and 1300° CB for approximately 12 h (d) fritting in vacuo at a temperature between 1850 and (e) impregnation with calcium and barium aluminates (f) elimination of the excess aluminate present on the surface by a chemical process (g) deposition of the high work function refractory metal film.
Claim 2
Dependent Claim
143 words
A process for producing a cathode formed from a matrix of a fritted powder metal impregnated with a barium compound, and a heating filament associated with said matrix, wherein the matrix is formed from a mixture of two metals, tungsten and another high work function refractory metal, and wherein the matrix is covered with a high work function refractory metal film, comprising the following successive stages: (a) mixing powders of tungsten and another high work function refractory metal (b) pressing the mixture between 7 and 10 t/cm 2 (c) prefritting under hydrogen at between 1100° and 1300° CB for approximately 12 h (d) fritting in vacuo at a temperature between 1850 and (e) impregnation with calcium and barium aluminates (f) elimination of the excess aluminate present on the surface by a chemical process (g) deposition of the high work function refractory metal film.
Claim 3
Dependent Claim
24 words
A process according to claim 1 wherein said high work function refractory metal is selected from the group comprising iridium, osmium, ruthenium, and rhenium.
Claim 4
Dependent Claim
13 words
A process according to claim 1 wherein the deposition is by cathodic sputtering.
Claim 5
Dependent Claim
12 words
A process according to claim 1 wherein the deposition is by evaporation.
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) | 1986-07-11 | 1987-01-10 | 1987-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-11 | 1991-01-10 | 1991-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-11 | 1995-01-10 | 1995-07-12 | $7700.00 | Window Closed / Lapsed |