US3163795A - Electron tube - Google Patents
Electron tube Download PDFInfo
- Publication number
- US3163795A US3163795A US23593A US2359360A US3163795A US 3163795 A US3163795 A US 3163795A US 23593 A US23593 A US 23593A US 2359360 A US2359360 A US 2359360A US 3163795 A US3163795 A US 3163795A
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- United States
- Prior art keywords
- cathodes
- cathode
- substrate
- nickel
- weight
- Prior art date
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 21
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 14
- 239000001301 oxygen Substances 0.000 claims description 14
- 229910052760 oxygen Inorganic materials 0.000 claims description 14
- 239000000758 substrate Substances 0.000 claims description 13
- 229910052759 nickel Inorganic materials 0.000 claims description 10
- 238000000859 sublimation Methods 0.000 description 10
- 230000008022 sublimation Effects 0.000 description 10
- 239000000203 mixture Substances 0.000 description 9
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 7
- 239000011777 magnesium Substances 0.000 description 7
- 229910052749 magnesium Inorganic materials 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 239000000654 additive Substances 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 239000001995 intermetallic alloy Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000004663 powder metallurgy Methods 0.000 description 2
- 102000010029 Homer Scaffolding Proteins Human genes 0.000 description 1
- 108010077223 Homer Scaffolding Proteins Proteins 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910000861 Mg alloy Inorganic materials 0.000 description 1
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000006735 deficit Effects 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- -1 magnesium Chemical class 0.000 description 1
- ATTFYOXEMHAYAX-UHFFFAOYSA-N magnesium nickel Chemical compound [Mg].[Ni] ATTFYOXEMHAYAX-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000010445 mica Substances 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
- H01J1/02—Main electrodes
- H01J1/13—Solid thermionic cathodes
- H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
- H01J1/22—Heaters
Definitions
- the cathode or electron emissive element of a cathode is conventionally composed of nickel or a nickel-rich alloy.
- the nickel or a mixture of nickel and certain well known additives as for example magnesium or tungsten, are first melted, either in air or in vacuo, to form a billet.
- the billet is subsequently rolled and annealed to form a sheet from which the cathode elements are subsequently fabricated.
- the composition of the cathode must be controlled within extremely close tolerances to prevent impairment of electrical and structural properties. Such control is extremely difficult, both because of these tolerances and further because extensive testing of the final product is necessary to determine whether or not the final product meets the necessary specifications. The rejection rate is extremely high, and a costly process results.
- cathodes so produced exhibited certain previously unsuspected but highly desirable properties.
- strength'of these cathodes substantially exceeded that of conventional indirectly heated cathodes, a highly significant improvement in a field where ever increasing emphasis has been placed on the development of stronger cathodes for use in electron discharge devices which are subject to severe vibrations and other types of mechanical stress.
- Another object is to reduce the costs of manufacturing cathodes through use of powder metallurgy techniques.
- Still another object is to provide a new process for producing cathodes.
- Yet another object is to provide new and improved cathodes, the strength of which substantially exceeds that of conventional cathodes.
- Still a further object is to reduce sublimation of metals, such as magnesium, during testing and operation of electron tubes.
- the composition of cathodes so formed can .be so accurately controlled that the compositions of successive batches (within the limits of experimental errors of analysis) have been found to be identical. Moreover, the strength of such cathodes is greatly increased over normal, the collapse strength being on the order of 2 to 3 times as large as that of conventional cathodes. Further, the sublimation rate of our cathodes when inserted into tubes and tested, is reduced by a factor of ten or more as compared to that conventionally obtained.
- the oxygen content of our cathodes is substantially in excess of the oxygen content of conventional cathodes, the ratio of the oxygen content of our cathode to that of conventional cathodes having otherwise substantially identical composition ranging from a minimum of about 2 to a maximum of 10 or more.
- an evacuated tube envelope 10 is secured to a tube base 12.
- An indirectly heated cathode containing one of our cathodes in the form of a sleeve or cylinder 18 coated with an electron emissive coating 19 and a folded heater 14 is positioned within the envelope.
- a grid wire 20 and an anode 22 are also supported within the envelope by mica spacers 2 4 and 26 which, in turn, are supported on wire supports 38 and 32.
- This cathode is fabricated by first thoroughly blending nickel powder of high purity either without additions or with powder additives in the form of metal or intermetallic alloys. The blended powders are then passed through a rolling mill to form a fragile porous sheet. The sheet is then sintered in an oxygen free atmosphere, such as argon or dry hydrogen, at a temperature falling within the approximate range 800 C.1150 C. until the porosity is greatly reduced and a strong relatively nonwithin the limits of experimental errors of analysis are identical in composition,
- an oxygen free atmosphere such as argon or dry hydrogen
- Example I A cathode sleeve was prepared having the following composition:
- the above alloy was analyzed for its gas content and was found to contain 0.001% by weight of nitrogen, 0.001% by weight of hydrogen, and 0.020% by weight of oxygen. 7
- a conventional nickel-magnesium cathode was analyzed and found to contain about 0.0042% by weight of oxygen, all other composition nanges being substantially identical with that of our cathode.
- Tubes of the type commercially designated as 12BA6 were fabricated using both types of cathodes and were tested. After a complete life test, the two types of cathodes. were removed from the tubes and again tested for collapse strength; the control cathode was found to have a stiffness of 180 grams while our cathode was found to have a stiffness of 420 grams.
- the conductivity as measured between the cathode and the control of tubes employing our cathodes ranged between 1/10 to 1/ 100 of the conductivity of tubes employing the controlcathode.
- the conductivity is directly related to. the degree of sublimation of the metallic elements other than nickel present within the cathode, and hence this test shows that the sublimation in the control tube is at least times as large as the sublimation in tubes employing our cathodes.
- oxygen content of our 4 sleeve could be decreased to about 0.010% by weight or could be increased to about 0.100% by weight without deleterious eifect. Reductions in oxygen content below 0.010% by weight resulted in decreased stiffness, while increasing the oxygen content above about 0.100% caused the sleeve to become somewhat brittle although the stillness was not adversely effected.
- cathodes Both types of cathodes, i.e. our cathodes and control cathodes, were fabricated from pure nickel and tested in the manner indicated. It was found that the emission of both cathodes decreased in the same proportion, the stiffness of both types of cathodes having about the same values as previously indicated.
- a cathode provided with a nickel substrate and an electron emissive layer in intimate contact with said substrate, said substrate having an oxygen content as expressed in percent by weight of said substrate which ranges between a minimum of about 0.01% and a maximum on the order of 0.1%.
- An electron discharge device having a cathode characterized by a high collapse strength and low sublimation, said cathode being provided with a nickel substrate and an electron emissive layer in intimate contact with said substrate, said substrate having an oxygen content which ranges between a minimum of about 0.01% by weight of said substrate and a maximum on the order of 0.1% by weight of said substrate.
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- Powder Metallurgy (AREA)
Description
Dec. 29, 1964 H. BENDER ETAL 3,163,795
ELECTRON TUBE Original Filed March 14, 1957 IN V EN TOR.
HARRY BENDER BY HARRY. P KUNG I ATTORNEY ire Stats 2 (Zlainrs. (Cl. SIB-27d) Our invention is directed toward electron discharge devices and more particularly relates to cathodes for use therein. This application is a division of application Serial No. 646,010, filed March 14, 1957, now abandoned.
As is Well known to the art, the cathode or electron emissive element of a cathode is conventionally composed of nickel or a nickel-rich alloy. In forming the element which is normally either planar or cylindrical in shape, the nickel or a mixture of nickel and certain well known additives, as for example magnesium or tungsten, are first melted, either in air or in vacuo, to form a billet. The billet is subsequently rolled and annealed to form a sheet from which the cathode elements are subsequently fabricated.
The composition of the cathode must be controlled within extremely close tolerances to prevent impairment of electrical and structural properties. Such control is extremely difficult, both because of these tolerances and further because extensive testing of the final product is necessary to determine whether or not the final product meets the necessary specifications. The rejection rate is extremely high, and a costly process results.
In our attempt to decrease the cathode rejection rate and thus to decrease the costs of producing cathodes, we discovered that, when powder metallurgy techniques were used in the manufacture of cathodes, a much higher degree of composition control was obtained and thus the rejection rate was sharply decreased.
Surprisingly, however, we also discovered that the cathodes so produced exhibited certain previously unsuspected but highly desirable properties. In particular, We found that the strength'of these cathodes substantially exceeded that of conventional indirectly heated cathodes, a highly significant improvement in a field where ever increasing emphasis has been placed on the development of stronger cathodes for use in electron discharge devices which are subject to severe vibrations and other types of mechanical stress.
We further discovered that when our cathodes were fabricated into electron tubes and tested, the sublima tion of certain additives, such as magnesium, was sharply reduced over that conventionally obtainable, thus minimizing leakage and other factors adversely aifected by such sublimation.
It is, therefore, an object of our invention to increase the strength of cathodes.
Another object is to reduce the costs of manufacturing cathodes through use of powder metallurgy techniques.
Still another object is to provide a new process for producing cathodes.
Yet another object is to provide new and improved cathodes, the strength of which substantially exceeds that of conventional cathodes.
Still a further object is to reduce sublimation of metals, such as magnesium, during testing and operation of electron tubes.
sheet which is then reduced to desired dimensions in ac-v cordance with conventional rolling and annealing schedules and then fabricated, for example, into planar or cylindrical cathodes.
The composition of cathodes so formed can .be so accurately controlled that the compositions of successive batches (within the limits of experimental errors of analysis) have been found to be identical. Moreover, the strength of such cathodes is greatly increased over normal, the collapse strength being on the order of 2 to 3 times as large as that of conventional cathodes. Further, the sublimation rate of our cathodes when inserted into tubes and tested, is reduced by a factor of ten or more as compared to that conventionally obtained.
We found that the oxygen content of our cathodes is substantially in excess of the oxygen content of conventional cathodes, the ratio of the oxygen content of our cathode to that of conventional cathodes having otherwise substantially identical composition ranging from a minimum of about 2 to a maximum of 10 or more.
While it is not our intention to be bound by theory, We believe that this increased oxygen content plays a primary role in the increased strength of our cathodes. More particularly, it is our belief that the oxide which is normally formed about the surface of metal powders is not reduced during rolling and sintering, but rather remains as discrete oxide particles within the sintered sheet. Such particles apparently inhibit grain movement and deformation, thus stiffening and strengthening the sheet structure.
Our invention will now be described in more detail with reference to the accompanying figure which shows an electron tube incorporating one of our cathodes.
Referring now to the figure, an evacuated tube envelope 10 is secured to a tube base 12. An indirectly heated cathode containing one of our cathodes in the form of a sleeve or cylinder 18 coated with an electron emissive coating 19 and a folded heater 14 is positioned within the envelope. A grid wire 20 and an anode 22 are also supported within the envelope by mica spacers 2 4 and 26 which, in turn, are supported on wire supports 38 and 32.
This cathode is fabricated by first thoroughly blending nickel powder of high purity either without additions or with powder additives in the form of metal or intermetallic alloys. The blended powders are then passed through a rolling mill to form a fragile porous sheet. The sheet is then sintered in an oxygen free atmosphere, such as argon or dry hydrogen, at a temperature falling within the approximate range 800 C.1150 C. until the porosity is greatly reduced and a strong relatively nonwithin the limits of experimental errors of analysis are identical in composition,
Example I A cathode sleeve was prepared having the following composition:
the remainder being nickel with small amounts of nitrogen, hydrogen and oxygen.
All trace ingredients other than magnesium were present in the high purity nickle powder; the magnesium was added in the form of an intermetallic alloy of nickel and magnesium, the chemical formula being Ni Mg.
The above alloy was analyzed for its gas content and was found to contain 0.001% by weight of nitrogen, 0.001% by weight of hydrogen, and 0.020% by weight of oxygen. 7
A conventional nickel-magnesium cathode was analyzed and found to contain about 0.0042% by weight of oxygen, all other composition nanges being substantially identical with that of our cathode.
Our cathode and the conventional or control cathode were tested for collapse strength; the control cathode was found to have a stiffness of 460 grams, while our cathode had a stiffness of 578 grams.
Tubes of the type commercially designated as 12BA6 were fabricated using both types of cathodes and were tested. After a complete life test, the two types of cathodes. were removed from the tubes and again tested for collapse strength; the control cathode was found to have a stiffness of 180 grams while our cathode was found to have a stiffness of 420 grams.
Emission measurements showed that the emission within tubes having our cathodes was at least equal to that obtained within tubes having the control cathodes.
The conductivity as measured between the cathode and the control of tubes employing our cathodes ranged between 1/10 to 1/ 100 of the conductivity of tubes employing the controlcathode. The conductivity is directly related to. the degree of sublimation of the metallic elements other than nickel present within the cathode, and hence this test shows that the sublimation in the control tube is at least times as large as the sublimation in tubes employing our cathodes.
Further tests showed that the oxygen content of our 4 sleeve could be decreased to about 0.010% by weight or could be increased to about 0.100% by weight without deleterious eifect. Reductions in oxygen content below 0.010% by weight resulted in decreased stiffness, while increasing the oxygen content above about 0.100% caused the sleeve to become somewhat brittle although the stillness was not adversely effected.
While the sublimation of our cathodes when incorporated in a tube was always less than conventionally obtainable, we found that best sublimation results were obtained by maintaining the magnesium content within the range 0.05% to 0.12% by weight.
Both types of cathodes, i.e. our cathodes and control cathodes, were fabricated from pure nickel and tested in the manner indicated. It was found that the emission of both cathodes decreased in the same proportion, the stiffness of both types of cathodes having about the same values as previously indicated.
While we have shown and pointed out our invention as applied above, it will be apparent to those skilled in the art that many modifications can be made within the scope and sphere of our invention as defined in the claims which follow:
What is claimed is:
l. A cathode provided with a nickel substrate and an electron emissive layer in intimate contact with said substrate, said substrate having an oxygen content as expressed in percent by weight of said substrate which ranges between a minimum of about 0.01% and a maximum on the order of 0.1%.
2. An electron discharge device having a cathode characterized by a high collapse strength and low sublimation, said cathode being provided with a nickel substrate and an electron emissive layer in intimate contact with said substrate, said substrate having an oxygen content which ranges between a minimum of about 0.01% by weight of said substrate and a maximum on the order of 0.1% by weight of said substrate.
References Cited by the Examiner UNITED STATES PATENTS 1,699,639 1/29 Van Gessel 313346 X 2,543,439 2/51 Coomes 313-346 X 2,566,115 8/51 Bounds 313346 X 2,657,325 10/53 Homer 313346 2,746,741 5/56 Naeser -208 2,814,564 11/57 Hayden 75-214 FOREIGN PATENTS 700,606 12/53 Great Britain.
DAVID J. GALVIN, Primary Examiner.
RALPH G. NILSON, ARTHUR GAUSS, Examiners.
Claims (1)
1. A CATHODE PROVIDED WITH A NICKEL SUBSTRATE AND AN ELECTRON EMMISSIVE LAYER ININTIMATE CONTACT WITH SAID SUBSTRATE, SAID SUBSTRATE HAVING AN OXYGEN CONTENT AS EXPRESSED IN PERCENT BY WEIGHT OF SAID SUBSTRATE WHICH RANGES BETWEEN A MINIMUM OF ABOUT 0.01% AND A MAXIMUM ON THE ORDER OF 0.1%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US23593A US3163795A (en) | 1957-03-14 | 1960-03-29 | Electron tube |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US64601057A | 1957-03-14 | 1957-03-14 | |
| US23593A US3163795A (en) | 1957-03-14 | 1960-03-29 | Electron tube |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3163795A true US3163795A (en) | 1964-12-29 |
Family
ID=26697369
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US23593A Expired - Lifetime US3163795A (en) | 1957-03-14 | 1960-03-29 | Electron tube |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US3163795A (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1699639A (en) * | 1924-02-12 | 1929-01-22 | Karel Marinus Van Gessel | Oxide cathode |
| US2543439A (en) * | 1945-05-02 | 1951-02-27 | Edward A Coomes | Method of manufacturing coated elements for electron tubes |
| US2566115A (en) * | 1950-07-21 | 1951-08-28 | Superior Tube Co | Alloy for cathode element |
| US2657325A (en) * | 1950-12-23 | 1953-10-27 | Sylvania Electric Prod | Electrode for electric discharge lamps |
| GB700606A (en) * | 1949-07-27 | 1953-12-09 | M O Valve Co Ltd | Improvements in or relating to thermionic cathodes and materials therefor |
| US2746741A (en) * | 1954-01-27 | 1956-05-22 | Mannesmann Ag | Apparatus for the production of wrought metal shapes from metal powder |
| US2814564A (en) * | 1957-07-17 | 1957-11-26 | Chemetals Corp | Method of purifying metals and consolidating the same |
-
1960
- 1960-03-29 US US23593A patent/US3163795A/en not_active Expired - Lifetime
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1699639A (en) * | 1924-02-12 | 1929-01-22 | Karel Marinus Van Gessel | Oxide cathode |
| US2543439A (en) * | 1945-05-02 | 1951-02-27 | Edward A Coomes | Method of manufacturing coated elements for electron tubes |
| GB700606A (en) * | 1949-07-27 | 1953-12-09 | M O Valve Co Ltd | Improvements in or relating to thermionic cathodes and materials therefor |
| US2566115A (en) * | 1950-07-21 | 1951-08-28 | Superior Tube Co | Alloy for cathode element |
| US2657325A (en) * | 1950-12-23 | 1953-10-27 | Sylvania Electric Prod | Electrode for electric discharge lamps |
| US2746741A (en) * | 1954-01-27 | 1956-05-22 | Mannesmann Ag | Apparatus for the production of wrought metal shapes from metal powder |
| US2814564A (en) * | 1957-07-17 | 1957-11-26 | Chemetals Corp | Method of purifying metals and consolidating the same |
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