US1867959A - Incandescent cathode for thermionic tubes and method of manufacturing same - Google Patents
Incandescent cathode for thermionic tubes and method of manufacturing same Download PDFInfo
- Publication number
- US1867959A US1867959A US389102A US38910229A US1867959A US 1867959 A US1867959 A US 1867959A US 389102 A US389102 A US 389102A US 38910229 A US38910229 A US 38910229A US 1867959 A US1867959 A US 1867959A
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- US
- United States
- Prior art keywords
- metal
- alkaline earth
- alkaline
- filament
- coating
- 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.)
- Expired - Lifetime
Links
- 238000004519 manufacturing process Methods 0.000 title description 11
- 229910052751 metal Inorganic materials 0.000 description 21
- 239000002184 metal Substances 0.000 description 21
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 19
- 150000001342 alkaline earth metals Chemical class 0.000 description 19
- 239000011248 coating agent Substances 0.000 description 15
- 238000000576 coating method Methods 0.000 description 15
- 150000001875 compounds Chemical class 0.000 description 13
- 238000000034 method Methods 0.000 description 9
- 229910052752 metalloid Inorganic materials 0.000 description 8
- 150000002738 metalloids Chemical class 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 5
- 230000001590 oxidative effect Effects 0.000 description 5
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 3
- 229910052788 barium Inorganic materials 0.000 description 3
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 3
- SDDGNMXIOGQCCH-UHFFFAOYSA-N 3-fluoro-n,n-dimethylaniline Chemical compound CN(C)C1=CC=CC(F)=C1 SDDGNMXIOGQCCH-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000005864 Sulphur Substances 0.000 description 2
- 229910052787 antimony Inorganic materials 0.000 description 2
- 229910052785 arsenic Inorganic materials 0.000 description 2
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 2
- RJWLRCHYHHXJLX-UHFFFAOYSA-N barium(2+);selenium(2-) Chemical compound [Se-2].[Ba+2] RJWLRCHYHHXJLX-UHFFFAOYSA-N 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052711 selenium Inorganic materials 0.000 description 2
- 239000011669 selenium Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052714 tellurium Inorganic materials 0.000 description 2
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000001341 alkaline earth metal compounds Chemical class 0.000 description 1
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- CJDPJFRMHVXWPT-UHFFFAOYSA-N barium sulfide Chemical compound [S-2].[Ba+2] CJDPJFRMHVXWPT-UHFFFAOYSA-N 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 150000003346 selenoethers Chemical class 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- XSOKHXFFCGXDJZ-UHFFFAOYSA-N telluride(2-) Chemical compound [Te-2] XSOKHXFFCGXDJZ-UHFFFAOYSA-N 0.000 description 1
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
- H01J9/042—Manufacture, activation of the emissive part
Definitions
- the invention relates to an incandescent cathode for thermionic tubes and methods of manufacturing the same, these cathodes be ing employed in transmitting and receiving 5 valves for radio purposes, rectifiers, Rontgentubes, etc.
- the oxide coating slows a noticeable resistance for the current passing from the cathode to the anode.
- this metal when deposited on an incandescent body, evaporates so quickly that it is impossible, to manufacture a durable cathode from the metal itself.
- the object of the invention is to do away with the difficulties mentioned.
- the cathode according to the invention is characterized by the application of one or more compounds of one or more alkaline or alkaline earth metals, which have a lower decomposition heat than the oxides.
- the alkaline, or alkaline earth metal compounds may comprise only two elements, viz, the metal and a metalloid.
- This expression metalloids may be defined as elements which may form oxides with acid properties and may combine with hydrogen.
- the compounds which may be applied are those of sulphur, selenium, 'tellurium, red phosphorus, arsenic and antimony.
- the method for the manufacture of the incandescent cathodes according to the invention consists substantially in precipitating the metalloid and the metal on the filament.
- the filament is submerged in a liquid containing substances which are disintegrated when heated, thereby supplying the desired metal-metalloid compounds.
- the compounds on the filament may also be produced from the elements themselves.
- the cathode according to the invention 0 can also be manufactured by previously coating the carrier with a metal, the metal being subsequently convertedinto a compound reacting with the alkaline or alkaline earth metal, to produce the desired compound. 35
- a filament of a metal with a high melting point e. g. tungsten, molybdenum, tantal, etc. is dipped in a solution of ammoniumselenotungstate, after which the 'fila ment is heated by passing a current therethrough in an atmosphere of nitrogen or one of the rare gases.
- tungstenselenide is present on the filament.
- the filament is then mounted in the tube, and the vapour of an alkaline earth-metal is precitated on the filament. Then the filament covered with metallic barium is heated, thus causing bariumselenide and 1 metallic tungsten to be produced on the filament.
- the coating obtained in this way has a great emission capacity and is better in every respect than the oxide coating.
- a cathode of this kind may be manufactured in the way described above, but with this difference that instead of xammoniumselenotungstate, e. g. a mixture of ammonium tungstate and ammoniumsulpho-, selenotellurotungstate is used.
- Very good results may be obtained by coating a filament galvanically with a metal, e. g. copper, and by converting this metal subsequently into sulphide, selenide, telluride, phosphide, arsenide or antimonide.
- a metal e. g. copper
- the method may then be as follows.
- the galvanically coated filament is mounted in the frame, and then the whole is placed under a bell jar which can be heated and evacuated. Under the jar there is a quantity of sulphur, selenium, tellurium, red phosphorus, arsenic or antimony. During the action of the vacuum pumps the jar is heated, after which the whole is allowed to cool down.
- the filament is now covered with a thin, equal coating consisting of a compound of the metal produced galvanically with the metalloid.
- the frame may then be introduced into the tube, and the further treatment corresponds to what has been described above.
- the process according to the invention has the advantage of the alkaline or alkaline earth metal being more easily liberated by an electrolytical action from the compounds mentioned, than from the oxide. Therefore the alkaline or alkaline earth metal is already liberated by a smaller emission current which eliminates the disadvantage of the emission in oxide cathodes decreasing, when a small emission current is used.
- the method according to the invention causes the alkaline or alkaline earth compound to be produced at a low temperature from the corresponding metal, and the metal compound supplied.
- a process for manufacturing incandescent cathodes comprising coating a core with a metal-metalloid compound and a metal of the group comprising the alkaline and alkaline earth metals; and heating the coated core in a non-oxidizing atmosphere to produce compounds of the metals of the group comprising the alkaline and alkaline earth metals with the said metalloid disintegrating more readily than the corresponding oxide.
- a process for manufacturing incandescent cathodes comprising submerging a core into a liquid containing substances which decompose by heating thereby supplying metal-metalloid compounds, coating the said core with a metal of the group comprising the alkaline and alkaline earth metals; and heating the core in a non-oxidizing atmosphere to produce compounds of the metal of the group comprising the alkaline and alkaline earth metals with the said metalloid disintegrating more readily than corresponding oxide.
- a process for manufacturing incandescent cathodes comprising coating a core with tungsten selenide and barium, and heat- 1ng the core in a non-oxidizing atmosphere to produce compounds of barium and sole nium.
- a process for manufacturing incandescent cathodes comprising coating a core with a metal-metalloid compound, an oxide and a metal of the group comprising the alkaline and alkaline earth metals; and heating the core in a non-oxidizing atmosphere to produce compounds of the metal of the group comprising the alkaline and alkaline earth metals with the said metalloid disin tegrating more readily than the corresponding oxide.
Description
Patented July 19, 1932 UNITED STATES PATENT OFFICE ERNST WINTER, OF NIJMEGEN, NETHERLANDS, ASSIGNOR TO NAAIVILOOZE VENNOOT- SCHAP SPLENDOR GLOEILAIVIPENFABRIEK SPLENDOR LAMIPWOBKS, OF NIJ'MEGEN,
NETHERLANDS INGANDESCENT OATHODE FOR THERMIONIC TUBES AND METHOD OF MANUFACTURING SAME No Drawing. Application filed August 28, 1929, Serial No. 389,102, and inthe Netherlands August 28, 1928. 1 v
The invention relates to an incandescent cathode for thermionic tubes and methods of manufacturing the same, these cathodes be ing employed in transmitting and receiving 5 valves for radio purposes, rectifiers, Rontgentubes, etc.
It has been proposed to manufacture incandescent cathodes with a high emission by coating the hot filament with a layer of oxide of one or more alkaline earth metals (socalled WVehnelt cathodes). The cathodes manufactured in this Way have, however, various disadvantages. It sometimes happens that the oxide coating crumbles off,
whereas the valves have unequal emission,
and do not all last the same length of time.
Moreover the oxide coating slows a noticeable resistance for the current passing from the cathode to the anode.
It has also been proposed to precipitate the alkaline earth metals from the vapour phase on a carrier, after which the carrier is heated in the presence of oxygen, the oxides thus being formed. Another way is that of previously oxidizing the carrier. The alkaline earth metals reduce these oxides, thus causing the alkaline earth oxides to be formed.
More recent experiments (e. g. l/Verner Espe-lVissenschaftliche Verolfentlichungen aus dem Siemens Konzern, Band V1927) have shown that the electron emission is caused by the alkaline earth metal itself. The alkaline earth metal required for the emission is liberated from the oxide coating by an electrolytical action. The metal evaporates slowly and is continually replenished. Consequently the oxide is used to supply the alkaline earth metal. The oxide is disintegrated later on electrolytically, in order to liberate the alkaline earth metal, for which a certain minimal tension, the decomposition tension, is required.
However, this metal, when deposited on an incandescent body, evaporates so quickly that it is impossible, to manufacture a durable cathode from the metal itself.
The object of the invention is to do away with the difficulties mentioned. The cathode according to the invention is characterized by the application of one or more compounds of one or more alkaline or alkaline earth metals, which have a lower decomposition heat than the oxides.
Another feature of the invention is that combinations are applied which do not react with the free metal. The alkaline, or alkaline earth metal compounds may comprise only two elements, viz, the metal and a metalloid. This expression metalloids may be defined as elements which may form oxides with acid properties and may combine with hydrogen. The compounds which may be applied are those of sulphur, selenium, 'tellurium, red phosphorus, arsenic and antimony.
The method for the manufacture of the incandescent cathodes according to the invention consists substantially in precipitating the metalloid and the metal on the filament.
According to an embodiment of the invention the filament is submerged in a liquid containing substances which are disintegrated when heated, thereby supplying the desired metal-metalloid compounds. By heating the filament treated in this way with an alkaline or alkaline earth metal, the compounds of the said metal with the metalloid are produced.
The compounds on the filament may also be produced from the elements themselves.
The cathode according to the invention 0 can also be manufactured by previously coating the carrier with a metal, the metal being subsequently convertedinto a compound reacting with the alkaline or alkaline earth metal, to produce the desired compound. 35
By way of example we shall now describe, in what way a bariumselenide cathode ismanufactured. A filament of a metal with a high melting point, e. g. tungsten, molybdenum, tantal, etc. is dipped in a solution of ammoniumselenotungstate, after which the 'fila ment is heated by passing a current therethrough in an atmosphere of nitrogen or one of the rare gases. When this has been done tungstenselenide is present on the filament. 9 The filament is then mounted in the tube, and the vapour of an alkaline earth-metal is precitated on the filament. Then the filament covered with metallic barium is heated, thus causing bariumselenide and 1 metallic tungsten to be produced on the filament. The coating obtained in this way has a great emission capacity and is better in every respect than the oxide coating.
It is also possible to start from the oxide cathode, and to use bariumsulphide, -selenide or -telluride. A cathode of this kind may be manufactured in the way described above, but with this difference that instead of xammoniumselenotungstate, e. g. a mixture of ammonium tungstate and ammoniumsulpho-, selenotellurotungstate is used.
Very good results may be obtained by coating a filament galvanically with a metal, e. g. copper, and by converting this metal subsequently into sulphide, selenide, telluride, phosphide, arsenide or antimonide.
The method may then be as follows. The galvanically coated filament is mounted in the frame, and then the whole is placed under a bell jar which can be heated and evacuated. Under the jar there is a quantity of sulphur, selenium, tellurium, red phosphorus, arsenic or antimony. During the action of the vacuum pumps the jar is heated, after which the whole is allowed to cool down. The filament is now covered with a thin, equal coating consisting of a compound of the metal produced galvanically with the metalloid. The frame may then be introduced into the tube, and the further treatment corresponds to what has been described above.
The process according to the invention has the advantage of the alkaline or alkaline earth metal being more easily liberated by an electrolytical action from the compounds mentioned, than from the oxide. Therefore the alkaline or alkaline earth metal is already liberated by a smaller emission current which eliminates the disadvantage of the emission in oxide cathodes decreasing, when a small emission current is used.
The method according to the invention causes the alkaline or alkaline earth compound to be produced at a low temperature from the corresponding metal, and the metal compound supplied.
The danger of the cathode being destroyed, the introduced metal evaporating, and the coating dropping off through the difference in the expansion coefficients of coating and carrier, is prevented, while the manufacture entails fewer difiiculties.
I claim:
1. A process for manufacturing incandescent cathodes comprising coating a core with a metal-metalloid compound and a metal of the group comprising the alkaline and alkaline earth metals; and heating the coated core in a non-oxidizing atmosphere to produce compounds of the metals of the group comprising the alkaline and alkaline earth metals with the said metalloid disintegrating more readily than the corresponding oxide.
2. A process for manufacturing incandescent cathodes comprising submerging a core into a liquid containing substances which decompose by heating thereby supplying metal-metalloid compounds, coating the said core with a metal of the group comprising the alkaline and alkaline earth metals; and heating the core in a non-oxidizing atmosphere to produce compounds of the metal of the group comprising the alkaline and alkaline earth metals with the said metalloid disintegrating more readily than corresponding oxide.
3. A process for manufacturing incandescent cathodes comprising coating a core with tungsten selenide and barium, and heat- 1ng the core in a non-oxidizing atmosphere to produce compounds of barium and sole nium.
4. A process for manufacturing incandescent cathodes comprising coating a core with a metal-metalloid compound, an oxide and a metal of the group comprising the alkaline and alkaline earth metals; and heating the core in a non-oxidizing atmosphere to produce compounds of the metal of the group comprising the alkaline and alkaline earth metals with the said metalloid disin tegrating more readily than the corresponding oxide.
In testimony whereof I. afiix my signature.
ERNST WINTER.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL1867959X | 1928-08-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US1867959A true US1867959A (en) | 1932-07-19 |
Family
ID=19873214
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US389102A Expired - Lifetime US1867959A (en) | 1928-08-28 | 1929-08-28 | Incandescent cathode for thermionic tubes and method of manufacturing same |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US1867959A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2522474A (en) * | 1942-07-02 | 1950-09-12 | Battelle Memorial Institute | Treatment of zinc surfaces |
-
1929
- 1929-08-28 US US389102A patent/US1867959A/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2522474A (en) * | 1942-07-02 | 1950-09-12 | Battelle Memorial Institute | Treatment of zinc surfaces |
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