GB2116773A - Cathode electrode assembly of an electron tube - Google Patents
Cathode electrode assembly of an electron tube Download PDFInfo
- Publication number
- GB2116773A GB2116773A GB08303599A GB8303599A GB2116773A GB 2116773 A GB2116773 A GB 2116773A GB 08303599 A GB08303599 A GB 08303599A GB 8303599 A GB8303599 A GB 8303599A GB 2116773 A GB2116773 A GB 2116773A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cathode electrode
- sleeve
- electrode assembly
- alloy
- electron tube
- 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.)
- Withdrawn
Links
- 229910001080 W alloy Inorganic materials 0.000 claims abstract description 11
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 10
- 239000003638 chemical reducing agent Substances 0.000 claims abstract 3
- 229910052721 tungsten Inorganic materials 0.000 abstract description 3
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 229910018487 Ni—Cr Inorganic materials 0.000 description 3
- 230000008602 contraction Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 229910001120 nichrome Inorganic materials 0.000 description 3
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 229910001930 tungsten oxide Inorganic materials 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 229910008938 W—Si Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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
- H01J1/26—Supports for the emissive material
-
- 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
- H01J1/14—Solid thermionic cathodes characterised by the material
Landscapes
- Solid Thermionic Cathode (AREA)
- Powder Metallurgy (AREA)
Abstract
In a cathode electrode assembly for an electron tube of the type comprising a cap having an electron emissive layer thereon and a sleeve supporting the cap, the sleeve is made of Ni-W alloy to which has been added from 0.1 to 5 wt% of a reducing agent such as one or more of Zr, Si, Al, and Mg. The Ni-W alloy may contain 10-15 wt.%W.
Description
SPECIFICATION
Cathode electrode assembly of an electron tube
This invention relates to an indirectly heated cathode electrode assembly of an electron tube such as a picture tube, and more particularly to an improvement of a sleeve for use in such an assembly for supporting a cap having an electron emissive layer thereon.
A cathode electrode assembly of the type mentioned is normally with a structure comprising a cap having an electron emissive layer thereon disposed opposite a control grid and an anode, and a cathode sleeve or a sleeve supporting the cap, the sleeve being supported in the tube by suitable members.
The present invention is particularly concerned with such a type of cathode electrode assembly wherein the cap is not formed integrally with the sleeve but is secured thereto by welding.
For such an assembly, a sleeve made of nichrome (Ni-Cr alloy) was popular in consideration of working or machining thereof and heat conductivity characteristic but chromium heated at high temperatures tends to be expelled to evaporate and the sleeve consequently contracts in the longitudinal direction. A typical sleeve (of 1.4 mmf and 6mm in length) shrinks as much as 50 ,um in length in 6,000 hours of operation. The phenomenon increases the spacing between the electron emissive layer and the control grid and creates a problem of degradation in electron emission.
Thus, a sleeve made of Ni-W alloy, in place of Ni-Cr alloy, having a lower heat conductivity was proposed as in Japanese Patent Publication No. 32458/82, for example.
The Ni-W alloy solved the problem of contraction which occurred to a sleeve made of nichrome, and additionally the durability against high temperatuve was enhanced compared with a sleeve made of nichrome. In the process of preparing a Ni-W alloy, however, some tungsten oxide is included and the presence of tungsten oxide causes blowholes in the material, which results in defective rolling.
It is, therefore, impossible to obtain a precisely formed sleeve.
An object of this invention is to provide a cathode electrode assembly for use in an electron tube which can be improved in its precision and heat conductivity to the cap.
To accomplish the above, according to the invention, there is provided a cathode electrode assembly of an electron tube of the type comprising a cap having an electron emissive layer thereon and a sleeve supporting said cap, said sleeve being made of Ni-W alloy, characterized in that 0.1 to 5 weight percent of reducing metal and/or Si is added to the
Ni-W alloy.
Descriptions of Preferred Embodiment
The invention will now be explained with reference to a preferred embodiment.
First, powder constituents of Ni, W, ZrHx and Si, W being 10 weight percent (hereinunder abbreviated as wt%), Zr and Si being 0.4 wt%, and Ni being the rest to complete to 100 wt%, are evenly mixed with a ball mill.
The mixture is then press moulded into a predetermined form and subsequently, sintered by radio frequency induction heating.
While being repeatedly annealed, the sintered body is cold rolled into a sheet having a thickness of approximately 0.5 mm, and the sheet is further thinned through a known squeezing process, while it is made cylindrical, so that a sleeve having a thickness of 20 to 30ym is formed. This way, ZrHx and Si which are both reducible metal reduce the surface of tungsten oxide by their cleaning effect, thereby making the sintered body denser. This also materializes such highly desirable effects as that the material for the subsequent rolling workability is greatly improved and that a sleeve of uniform density (without blowholes) is obtainable.
In the preferred embodiment above, the weight percentage of W is 10 but the contraction of a sleeve can be suppressed to the level of desired values when the weight percentage is preferably with the range of 10 to 1 5.
When the weight percentage is less than 10, however, the heat conductivity increases compared with that of Ni-Cr alloy, and when more than 15, the sintered body crumbles and can not be rolled smoothly. As for Zr and Si, it is ascertained that the workability of Ni-W alloy can be improved when the weight percentage of each Zr and Si is 0.1 to 5, though preferably 1 to 5. When the weight percentage of each Zr and Si is more than 5, the Ni-W-Zr of
Ni-W-Si alloy cannot take the form of solid solution and the form of the sleeve tends to be distorted because of segregation of Zr of
Si. When the weight percentage of Zr or Si is less than 0.1, the effect can not be sufficient.
Further, because the weight percentages of Zr and Si added are minimal, Zr and Si do not affect the heat conductivity. In this sense, the alloy is similar to the conventional Ni-W alloy.
Besides the reducing metal Zr, Si and the like, Al, Mg and the like can also be used, either singularly of in plurality as in the preferred embodiment.
Thus, according to this invention, the contraction of the sleeve can be suppressed since ther is no chromium included, which eliminates a variation of the distance between the electron emissive surface of the cathode electrode and the control grid electrode and also the problem of decreased electron emission during the operation of the electron tube, and on account of the addition of reducing metal or Si, the workability of rolling for forming a sleeve can be improved.
Although it is advantageous to form alloys with powders of metals and to sinter the moulded body by radio frequency induction heating, other method, for example vacuum melting can also be used.
Claims (4)
1. A cathode electrode assembly for an electron tube comprising a cap having an electron emissive layer thereon and a sleeve fitting into and supporting said cap, said sleeve being made of Ni-W alloy containing from 0.1 to 5 wt% of reducing agent.
2. A cathode electrode assembly according to claim 1, wherein the reducing agent is at least one of Zr, Si, Al and Mg.
3. A cathode electrode assembly according to claim 1 or claim 2, wherein the W in the Ni-W alloy is of 10 to 15 wt%.
4. A cathode electrode assembly for an electron tube substantially as described herein as a preferred embodiment.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57036437A JPS58154130A (en) | 1982-03-10 | 1982-03-10 | Cathode for electron tube |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8303599D0 GB8303599D0 (en) | 1983-03-16 |
| GB2116773A true GB2116773A (en) | 1983-09-28 |
Family
ID=12469784
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08303599A Withdrawn GB2116773A (en) | 1982-03-10 | 1983-02-09 | Cathode electrode assembly of an electron tube |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS58154130A (en) |
| GB (1) | GB2116773A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2421535C1 (en) * | 2007-04-17 | 2011-06-20 | Тиссенкрупп Фдм Гмбх | Metal foil |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1225093A (en) * | 1968-03-22 | 1971-03-17 | ||
| GB2012474A (en) * | 1977-12-26 | 1979-07-25 | Hitachi Ltd | Thermionic emission cathodes |
| GB1561736A (en) * | 1975-11-07 | 1980-02-27 | Hitachi Ltd | Base metal plate for preparing the same |
| GB1562554A (en) * | 1976-03-09 | 1980-03-12 | Hitachi Ltd | Process for producing a directly heated type cathode for cathode ray tube |
| GB1562362A (en) * | 1976-07-07 | 1980-03-12 | Hitachi Ltd | Directly heated type cathode for cathode ray tube and process for producing the same cathode |
| GB2041638A (en) * | 1979-01-19 | 1980-09-10 | Hitachi Ltd | Directly heated cathode for electron tube |
| GB2060245A (en) * | 1979-09-12 | 1981-04-29 | Hitachi Ltd | Oxide-coated cathodes |
-
1982
- 1982-03-10 JP JP57036437A patent/JPS58154130A/en active Pending
-
1983
- 1983-02-09 GB GB08303599A patent/GB2116773A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1225093A (en) * | 1968-03-22 | 1971-03-17 | ||
| GB1561736A (en) * | 1975-11-07 | 1980-02-27 | Hitachi Ltd | Base metal plate for preparing the same |
| GB1562554A (en) * | 1976-03-09 | 1980-03-12 | Hitachi Ltd | Process for producing a directly heated type cathode for cathode ray tube |
| GB1562362A (en) * | 1976-07-07 | 1980-03-12 | Hitachi Ltd | Directly heated type cathode for cathode ray tube and process for producing the same cathode |
| GB2012474A (en) * | 1977-12-26 | 1979-07-25 | Hitachi Ltd | Thermionic emission cathodes |
| GB2041638A (en) * | 1979-01-19 | 1980-09-10 | Hitachi Ltd | Directly heated cathode for electron tube |
| GB2060245A (en) * | 1979-09-12 | 1981-04-29 | Hitachi Ltd | Oxide-coated cathodes |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2421535C1 (en) * | 2007-04-17 | 2011-06-20 | Тиссенкрупп Фдм Гмбх | Metal foil |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58154130A (en) | 1983-09-13 |
| GB8303599D0 (en) | 1983-03-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |