Patent US3736658A successfully refreshed from Google Patents.
US3736658A
Expired / Lapsed
US
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Thermionic gas-pressure-bonded sheathed insulators and method of producing same
Assignee: United States Atomic Energy Commission
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Filing: 1970-10-12
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Granted: 1973-06-05
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Expires: 1990-10-12
Abstract
Abstract The collector of a thermionic converter, an insulator, and a metal sheath for the insulator are directly gas-pressure-bonded together such that the trilayer thus formed is stress relieved and maintains good structural integrity during machining and during thermocycling caused by operation of the converter. The insulator is alumina and the collector and sheath consist either of niobium metal or Nb-1 wt percent Zr alloy.
Inventors
- 👤 C Weaver
- 👤 W Ranken
- 👤 R Lawton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:23
CPC Classifications
C; C04; C04B; C04B37/00; C04B37/02; C04B37/021; C04B35/00; C04B35/622; C04B35/64; C04B35/645; C04B35/6455; H; H01; H01B; H01B3/00; H01B3/002; H01B3/004; H01J; H01J45/00; C04B2235/00; C04B2235/65; C04B2235/656; C04B2235/6567; C04B2235/658; C04B2235/6581; C04B2237/00; C04B2237/30; C04B2237/32; C04B2237/34; C04B2237/343; C04B2237/40; C04B2237/403; C04B2237/50; C04B2237/52; C04B2237/525; C04B2237/60; C04B2237/62; C04B2237/68; C04B2237/70; C04B2237/704; C04B2237/706; Y; Y10; Y10S; Y10S228/00; Y10S228/903; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49227
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
28 words
The method of claim 1 wherein said metal jacket is selected from the class consisting of niobium and Nb-1 wt percent Zr alloy and said ceramic is alumina.
Claim 2
Dependent Claim
12 words
The method of claim 2 wherein said ceramic has a cylindrical configuration.
Claim 3
Dependent Claim
75 words
The method of claim 3 wherein (a) said jacketed cylinder is heated to 1550*C in a helium atmosphere, (b) at 1550*C said jacketed cylinder is subjected to a helium gas pressure of 10,000 psi and held at said pressure and temperature for 3 hours, (c) the pressure is then slowly reduced to near ambient over about a 7-hour period while the temperature remains constant at 1550*C, and (d) the temperature is then reduced to ambient.
Claim 4
Dependent Claim
11 words
The method of claim 4 wherein said metal jacket is niobium.
Claim 5
Dependent Claim
15 words
The method of claim 4 wherein said metal jacket is Nb-1 wt percent Zr alloy.
Claim 6
Independent Claim
114 words
A method of producing a thermionic converter trilayer which comprises: (a) forming an evacuated, gas-tight metal Jacket around and in close proximity to a ceramic cylinder, said metal jacket being selected from the class consisting of niobium and Nb-1 wt percent Zr alloy and said ceramic cylinder being alumina, (b) heating said jacketed cylinder to 1550*C in a helium atmosphere, (c) at 1550*C subjecting said jacketed cylinder to a helium gas pressure of 10,000 psi and holding it at said pressure and temperature for 3 hours, (d) slowly reducing the pressure to near ambient over about a 7-hour period while the temperature remains constant at 1550*C, and (e) then reducing the temperature to ambient.
Claim 7
Dependent Claim
11 words
The method of claim 7 wherein said metal jacket is niobium.
Claim 8
Dependent Claim
15 words
The method of claim 7 wherein said metal jacket is Nb-1 wt percent Zr alloy.
Claim 9
Dependent Claim
123 words
In a thermionic converter having (a) a Nb-1 wt percent Zr collector, (b) a heat sink for removing heat from said collector, (c) an Al2O3 electrical insulator in contact with said collector and between said collector and said heat sink, (d) a Nb-1 wt percent Zr protective metal sheath for said insulator, (e) an emitter spaced from said collector, (f) an easily ionized gas between said emitter and collector, (g) a heat source, (h) heat transferring means for heating said emitter and ionizing said gas by said heat source, and (i) means for taking out the electrical power generated between said emitter and collector, the improvement consisting of a stress-relieved diffusion bond between said insulator and said collector and said protective metal sheath.
Claim 10
Dependent Claim
15 words
A thermionic converter trilayer comprising stress-relieved, diffusion bonded Nb-1 wt percent Zr/Al2O3/Nb-1 wt percent Zr.
Claim 11
Dependent Claim
21 words
A machinable, stress-relieved electrical insulator for use in a thermionic converter which comprises diffusion-bonded Nb-1 wt percent Zr/Al2O3/Nb-1 wt percent Zr.
Claim 12
Independent Claim
157 words
A method of producing a machinable, stress-relieved, pressure-bonded ceramic-to-metal seal which comprises: (a) forming an evacuated gas-tight metal jacket around and in close proximity to a ceramic, said metal and said ceramic having closely similar coefficients of thermal expansion and high creep rates at sufficiently elevated temperatures, (b) subjecting said jacketed ceramic to a combination of temperature and pressure sufficient to bond contacting metal-ceramic surfaces within said jacketed ceramic, said temperature also being sufficient to produce a high creep rate in said ceramic and metal components, (c) holding at said temperature while slowly reducing the pressure to ambient over a time sufficient to stress relieve said bond, (d) reducing the temperature to ambient, (e) cutting the jacketed ceramic to a desired length, (f) etching away one side of the metal jacket, (g) machining the Al2O3 away from the ends of the remaining metal jacket as desired, and (h) parting the remaining metal jacket as desired by machining.
Claim 13
Dependent Claim
28 words
The method of claim 13 wherein said metal jacket is selected from the class consisting of niobium and Nb-1 wt percent Zr alloy and said ceramic is alumina.
Claim 14
Dependent Claim
12 words
The method of claim 14 wherein said ceramic has a cylindrical configuration.
Claim 15
Dependent Claim
75 words
The method of claim 15 wherein (a) said jacketed cylinder is heated to 1550*C in a helium atmosphere, (b) at 1550*C said jacketed cylinder is subjected to a helium gas pressure of 10,000 psi and held at said pressure and temperature for 3 hours, (c) the pressure is then slowly reduced to near ambient over about a 7-hour period while the temperature remains constant at 1550*C, and (d) the temperature is then reduced to ambient.
Claim 16
Dependent Claim
11 words
The method of claim 16 wherein said metal jacket is niobium.
Claim 17
Dependent Claim
15 words
The method of claim 16 wherein said metal jacket is Nb-1 wt percent Zr alloy.
Claim 18
Dependent Claim
20 words
A ceramic-to-metal seal for use in a high temperature environment which comprises Nb-1 wt percent Zr diffusion bonded to Al2O3.
References Cited (Backward Citations)
US2647218A
Cited
US3656225A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |