US4279784A
Expired / Lapsed
US
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Thermionic emission cathodes
Assignee: Hitachi Ltd
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Filing: 1978-12-26
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Granted: 1981-07-21
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Expires: 1998-12-26
Abstract
Abstract A thermionic emission cathode comprising a base metal made of nickel-tungsten series alloy, for example an alloy comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, and an emitter layer, which is formed on the base, made from a mixture of (a) tungsten powder or nickel-tungsten alloy powder comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, (b) Ba 3 WO 6 powder and (c) zirconium powder or ZrH 2 powder, and if necessary interposing a powder layer between the base and the emitter layer, said powder layer having the same composition as the base metal and a particle size of 1 to 10 μm sealed on the surface of the base with a distribution density of 0.5 to 5.0 mg/cm 2 , can be applied to both directly and indirectly heated type cathodes. Said cathode has such advantages as being able to be miniaturized and to have high current density.
Inventors
- 👤 Akira Misumi
- 👤 Shunji Saito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 00:20
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/13
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
69 words
A thermionic emission cathode which comprises a base made of a nickel-tungsten series alloy comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, and an emitter layer, which is formed on the base and which is made from a mixture of (a) tungsten powder or nickel-tungsten alloy powder, (b) Ba 3 WO 6 powder and (c) zirconium powder or ZrH 2 powder.
Claim 2
Dependent Claim
69 words
A thermionic emission cathode which comprises a base made of a nickel-tungsten series alloy comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, and an emitter layer, which is formed on the base and which is made from a mixture of (a) tungsten powder or nickel-tungsten alloy powder, (b) Ba 3 WO 6 powder and (c) zirconium powder or ZrH 2 powder.
Claim 3
Dependent Claim
51 words
A thermionic emission cathode according to claim 1, wherein the base is made of an alloy comprising 10 to 30% by weight of tungsten, a small amount of at least one reducing agent selected from the group consisting of Zr, Mg, Si, Al, U and Th, and the remainder being nickel.
Claim 4
Dependent Claim
62 words
A thermionic emission cathode according to claim 1, wherein the base is made of an alloy comprising 10 to 30% by weight of tungsten and molybdenum or/and rhenium, tungsten being 5% by weight or more, a small amount of at least one reducing agent selected from the group consisting of Zr, Mg, Si, Al, U and Th, and the remainder being nickel.
Claim 5
Dependent Claim
36 words
A thermionic emission cathode according to claim 1, wherein the component (a) in the emitter layer is nickel-tungsten alloy powder comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten.
Claim 6
Dependent Claim
19 words
A thermionic emission cathode according to claim 1, wherein the component (a) in the emitter layer is tungsten powder.
Claim 7
Dependent Claim
34 words
A thermionic emission cathode according to claim 1, 2, or 3, wherein the emitter layer is made from a mixture of (a) tungsten powder, (b) Ba 3 WO 6 powder and (c) zirconium powder.
Claim 8
Dependent Claim
51 words
A thermionic emission cathode according to claim 1, 2, or 3, wherein the emitter layer is made from a mixture of (a) nickel-tungsten alloy powder comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, (b) Ba 3 WO 6 powder and (c) zirconium powder.
Claim 9
Dependent Claim
62 words
A thermionic emission cathode according to claim 1, 2, or 3, which further comprises a powder layer between the base and the emitter layer by sealing nickel-tungsten alloy powder having the same composition as the base metal and a particle size of 1 to 10 μm on the surface of base with a distribution density of 0.5 to 5.0 mg/cm 2 .
Claim 10
Dependent Claim
27 words
A thermionic emission cathode according to claim 8, wherein the component (a) in the emitter layer is nickel-alloy powder having the same composition as the base metal.
Claim 11
Dependent Claim
19 words
A thermionic emission cathode according to claim 8, wherein the component (a) in the emitter layer is tungsten powder.
Claim 12
Dependent Claim
31 words
A thermionic emission cathode according to claim 8, wherein the emitter layer is made from a mixture of (a) tungsten powder, (b) Ba 3 WO 6 powder and (c) zirconium powder.
Claim 13
Dependent Claim
48 words
A thermionic emission cathode according to claim 8, wherein the emitter layer is made from a mixture of (a) nickel-tungsten alloy powder comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, (b) Ba 3 WO 6 powder and (c) zirconium powder.
Claim 14
Dependent Claim
49 words
A thermionic emission cathode according to claims 1, wherein the emitter layer is made from a mixture of (a) 88 to 90% by weight of tungsten powder, (b) 7.5 to 11% by weight of Ba 3 WO 6 powder and (c) 0.5 to 1.8% by weight of zirconium powder.
Claim 15
Dependent Claim
25 words
A thermionic emission cathode according to claims 1, 2 or 3, said cathode further comprises a heater for heating said base and said emitter layer.
Claim 16
Dependent Claim
22 words
A thermionic emission cathode according to claim 8, said cathode further comprises a heater for heating said base and said emitter layer.
Claim 17
Dependent Claim
22 words
A thermionic emission cathode according to claims 1, 2 or 3, wherein said base having terminals connected to an electric power supply.
Claim 18
Dependent Claim
19 words
A thermionic emission cathode according to claim 8, wherein said base having terminals connected to an electric power supply.
Claim 19
Dependent Claim
119 words
A process for producing a thermionic emission cathode which comprises forming a base having a cylindrical or polygonal prism form and having a flat portion at the top thereof by using an alloy of nickel-tungsten series comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, coating a mixture of (a) tungsten powder or nickel-tungsten alloy powder comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, (b) Ba 3 WO 6 powder and (c) zirconium powder or ZrH 2 powder, on the base, and sintering at a temperature of from 700° C. to 1000° C. under vacuum or in hydrogen gas to form an emitter layer.
Claim 20
Dependent Claim
119 words
A process for producing a thermionic emission cathode which comprises forming a base having a cylindrical or polygonal prism form and having a flat portion at the top thereof by using an alloy of nickel-tungsten series comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, coating a mixture of (a) tungsten powder or nickel-tungsten alloy powder comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, (b) Ba 3 WO 6 powder and (c) zirconium powder or ZrH 2 powder, on the base, and sintering at a temperature of from 700° C. to 1000° C. under vacuum or in hydrogen gas to form an emitter layer.
Claim 21
Dependent Claim
60 words
A process according to claim 18, which further comprises forming a powder layer between the base and the emitter layer by sealing nickel-tungsten alloy powder having the same composition as the base metal alloy and a particle size of 1 to 10 μm on the surface of the base with a distribution density of 0.5 to 5.0 mg/cm 2 .
Claim 22
Dependent Claim
66 words
A thermionic emission cathode according to claim 1, wherein the emitter layer is made from a mixture of (a) 88 to 90% by weight of a nickel-tungsten alloy comprising 90 to 70% by weight of nickel and 10 to 33% by weight of tungsten, (b) 7.5 to 11% by weight of Ba 2 WO 6 powder, and (c) 0.5 to 1.8% by weight of zirconium powder.
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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) | 1984-07-20 | 1985-01-19 | 1985-07-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-07-20 | 1989-01-19 | 1989-07-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-07-20 | 1993-01-19 | 1993-07-21 | $7700.00 | Window Closed / Lapsed |