US2246162A - Thermionic cathode treatment - Google Patents
Thermionic cathode treatment Download PDFInfo
- Publication number
- US2246162A US2246162A US289923A US28992339A US2246162A US 2246162 A US2246162 A US 2246162A US 289923 A US289923 A US 289923A US 28992339 A US28992339 A US 28992339A US 2246162 A US2246162 A US 2246162A
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- US
- United States
- Prior art keywords
- cathodes
- sulphur
- nickel
- thermionic
- thermionic cathode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 11
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 8
- 239000005864 Sulphur Substances 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 5
- 239000010953 base metal Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- 229910000990 Ni alloy Inorganic materials 0.000 description 2
- 230000003213 activating effect Effects 0.000 description 2
- 229910052788 barium Inorganic materials 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 2
- 230000002939 deleterious effect Effects 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 238000010310 metallurgical process Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000012070 reactive reagent Substances 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/02—Manufacture of electrodes or electrode systems
- H01J9/04—Manufacture of electrodes or electrode systems of thermionic cathodes
Definitions
- the present invention is an improvement in thermionic cathodes of the activated type in which the base material consists of nickeliferous material, that is, nickel or an alloy of nickel.
- Oxide-coated cathodes sometimes known as Wehnelt cathodes, when employed in gaseous discharge lamps, in cathode ray tubes, or in other thermionic devices, after a period of use lose their electron emissivity. In some cases cathodes which no longer are effectively electron-emissive can be observed still to be coated with oxide.
- the accompanying drawing illustrates conventionally a thermionic device to which my invention is applicable.
- the nickeliferous material is heated in contact with a reagent which is reactive towards sulphur at high temperature.
- a reagent which is reactive towards sulphur at high temperature.
- the wire strip, wire or other article of nickel, or one of its alloys is heated at a temperature of about 1000 C. while embedded in an oxygenous alkaline earth compound which is sulphur-reactive, the heating preferably taking place in an inert atmosphere or in a vacuum.
- Finely divided carbonate of barium or other alkaline earth metals, and similarly the oxides of such metals in powdered form, may be used as the sulphur-reactive reagent.
- the length of time of heating will vary with the thickness of the nickeliferous material. For a material having a thickness of about 0.5 millimeter or less, good results can be obtained by heat treatment under the described conditions continued for about 1 hour.
- Nickel or nickel alloy metal after having been subjected to this process, is fabricated into form suitable for the production of cathodes and is coated with activating material, for example, a
- the coating subsequently is converted to an oxide and is treated to become active or electron-emitting in accordance with well understood methods.
- the drawing illustrates a rectifier as one form of thermionic cathode device to which my invention is applicable. It comprises a container I in which is mounted a cathode assembly 2 and an anode 3. 'The cathode assembly comprises a heat shield 4, in which are disposed a heater 5 and an oxide-coated ribbon cathode 6 which is wound on a support 1. The cathode is treated in accordance with the present invention. The heater and ribbon cathode are connected electrically as usual to external contacts 8 which are mounted on a base 9. The anode 3 is connected to an external contact Ill.
- the container contains an appropriate gas filling. A charge of mercury (not shown) which furnishes vapor during operation commonly is used. Electrons emitted from the heated cathode 6 pass through an opening in the shield 4 (not shown) to the anode 3.
- Cathodes made from sulphur-free metal have longer useful operating lives in thermionic devices than cathodes containing cores or base metal made of commercial metal which contains sulphur.
- the step in the process of manufacturing oxide-coated cathodes which consists in subjecting the nickeliferous base metal for such cathodes to a heat treatment at about 1000 C. while packed in oxygenous alkaline earth compound until the residual sulphur in such metal has been substantially eliminated.
- a step in the manufacture of oxide-coated thermionic cathodes comprising nickeliferous base metal which comprises heating base metal for such cathodes to about 1000 C. while packed in barium carbonate and preliminary to coating such material with an oxide layer.
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Solid Thermionic Cathode (AREA)
Description
June 17, 1941. M. BENJAMIN THERMiONIC CATHODE TREATMENT Filed Aug. 12, 1939 Patented June 17, 1941 UETED THERMIONIO GATHODE; TREATIVIENT Mark Benjamin, ,Wembley, England, assignor to General Electric Company, a corporation of New York Application August 12, 1939, Serial No. 289,923 In Great Britain August 17, 1938 3 Claims.
The present invention is an improvement in thermionic cathodes of the activated type in which the base material consists of nickeliferous material, that is, nickel or an alloy of nickel.
Oxide-coated cathodes, sometimes known as Wehnelt cathodes, when employed in gaseous discharge lamps, in cathode ray tubes, or in other thermionic devices, after a period of use lose their electron emissivity. In some cases cathodes which no longer are effectively electron-emissive can be observed still to be coated with oxide.
I have discovered that one of the causes of loss of activity of oxide-coated cathodes is the deleterious effect of sulphur which is present ordinarily in the metal base or core. Commercial nickel contains appreciable quantities of sulphur which known metallurgical processes are not capable of removing sufliciently to avoid such deleterious effect on cathodes made therefrom.
In accordance with the method step constituting my invention, residual sulphur is removed substantially entirely from articles of nickel, such as nickel wire strip or sheet material, or in any event to such extent that any remainder is harmless to electron emission of cathodes made from such material.
The accompanying drawing illustrates conventionally a thermionic device to which my invention is applicable. In carrying out my invention the nickeliferous material is heated in contact with a reagent which is reactive towards sulphur at high temperature. For example, the wire strip, wire or other article of nickel, or one of its alloys, is heated at a temperature of about 1000 C. while embedded in an oxygenous alkaline earth compound which is sulphur-reactive, the heating preferably taking place in an inert atmosphere or in a vacuum. Finely divided carbonate of barium or other alkaline earth metals, and similarly the oxides of such metals in powdered form, may be used as the sulphur-reactive reagent.
The length of time of heating will vary with the thickness of the nickeliferous material. For a material having a thickness of about 0.5 millimeter or less, good results can be obtained by heat treatment under the described conditions continued for about 1 hour.
Nickel or nickel alloy metal, after having been subjected to this process, is fabricated into form suitable for the production of cathodes and is coated with activating material, for example, a
carbonate of barium, strontium, or calcium, or an.
appropriate mixture. The coating subsequently is converted to an oxide and is treated to become active or electron-emitting in accordance with well understood methods.
The drawing illustrates a rectifier as one form of thermionic cathode device to which my invention is applicable. It comprises a container I in which is mounted a cathode assembly 2 and an anode 3. 'The cathode assembly comprises a heat shield 4, in which are disposed a heater 5 and an oxide-coated ribbon cathode 6 which is wound on a support 1. The cathode is treated in accordance with the present invention. The heater and ribbon cathode are connected electrically as usual to external contacts 8 which are mounted on a base 9. The anode 3 is connected to an external contact Ill. The container contains an appropriate gas filling. A charge of mercury (not shown) which furnishes vapor during operation commonly is used. Electrons emitted from the heated cathode 6 pass through an opening in the shield 4 (not shown) to the anode 3.
Cathodes made from sulphur-free metal have longer useful operating lives in thermionic devices than cathodes containing cores or base metal made of commercial metal which contains sulphur.
What I claim as new and desire to secure by Letters Patent of the United States is:
1. The step in the process of manufacturing oxide-coated cathodes which consists in subjecting the nickeliferous base metal for such cathodes to a heat treatment at about 1000 C. while packed in oxygenous alkaline earth compound until the residual sulphur in such metal has been substantially eliminated.
2. A step in the manufacture of oxide-coated thermionic cathodes comprising nickeliferous base metal which comprises heating base metal for such cathodes to about 1000 C. while packed in barium carbonate and preliminary to coating such material with an oxide layer.
3. The method of manufacturing cathodes for electric discharge devices from nickel bases containing sulphur which consists in subjecting said bases to a purifying treatment for aboutone hour at about 1000" C. while packed in oxygenous alkaline earth compound whereby sulphur is substantially eliminated and thereafter coating said bases with activating material.
MARK BENJAMIN.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB2246162X | 1938-08-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2246162A true US2246162A (en) | 1941-06-17 |
Family
ID=10902154
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US289923A Expired - Lifetime US2246162A (en) | 1938-08-17 | 1939-08-12 | Thermionic cathode treatment |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2246162A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2586768A (en) * | 1949-02-24 | 1952-02-26 | Driver Harris Co | Vacuum tube electrode element |
| US2819991A (en) * | 1952-08-30 | 1958-01-14 | Rca Corp | Carburized thoriated tungsten electrode and method of enhancing its emissivity |
| US2916652A (en) * | 1955-02-04 | 1959-12-08 | Raytheon Co | Control of electron emission in cathode assemblies |
| US3439210A (en) * | 1966-01-03 | 1969-04-15 | Hughes Aircraft Co | Thermionic emission cathode having reduced frontal area and enlarged emission area for ion bombardment environment |
| US6333121B1 (en) | 1992-10-13 | 2001-12-25 | General Electric Company | Low-sulfur article having a platinum-aluminide protective layer and its preparation |
| US6656605B1 (en) | 1992-10-13 | 2003-12-02 | General Electric Company | Low-sulfur article coated with a platinum-group metal and a ceramic layer, and its preparation |
-
1939
- 1939-08-12 US US289923A patent/US2246162A/en not_active Expired - Lifetime
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2586768A (en) * | 1949-02-24 | 1952-02-26 | Driver Harris Co | Vacuum tube electrode element |
| US2819991A (en) * | 1952-08-30 | 1958-01-14 | Rca Corp | Carburized thoriated tungsten electrode and method of enhancing its emissivity |
| US2916652A (en) * | 1955-02-04 | 1959-12-08 | Raytheon Co | Control of electron emission in cathode assemblies |
| US3439210A (en) * | 1966-01-03 | 1969-04-15 | Hughes Aircraft Co | Thermionic emission cathode having reduced frontal area and enlarged emission area for ion bombardment environment |
| US6333121B1 (en) | 1992-10-13 | 2001-12-25 | General Electric Company | Low-sulfur article having a platinum-aluminide protective layer and its preparation |
| US6656533B2 (en) | 1992-10-13 | 2003-12-02 | William S. Walston | Low-sulfur article having a platinum-aluminide protective layer, and its preparation |
| US6656605B1 (en) | 1992-10-13 | 2003-12-02 | General Electric Company | Low-sulfur article coated with a platinum-group metal and a ceramic layer, and its preparation |
| US20040123923A1 (en) * | 1992-10-13 | 2004-07-01 | Walston William S. | Low sulfur article having a platinum-aluminide protective layer, and its preparation |
| US6797408B2 (en) | 1992-10-13 | 2004-09-28 | General Electric Company | Low-sulfur article having a platinum-aluminide protective layer, and its preparation |
| US20050121116A1 (en) * | 1992-10-13 | 2005-06-09 | General Electric Company | Low-sulfur article having a platinum aluminide protective layer and its preparation |
| US6969558B2 (en) | 1992-10-13 | 2005-11-29 | General Electric Company | Low sulfur article having a platinum-aluminide protective layer, and its preparation |
| US7510779B2 (en) | 1992-10-13 | 2009-03-31 | General Electric Company | Low-sulfur article having a platinum aluminide protective layer and its preparation |
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