US3898721A - Diffusion bonded cathode for electron discharge device - Google Patents
Diffusion bonded cathode for electron discharge device Download PDFInfo
- Publication number
- US3898721A US3898721A US361830A US36183073A US3898721A US 3898721 A US3898721 A US 3898721A US 361830 A US361830 A US 361830A US 36183073 A US36183073 A US 36183073A US 3898721 A US3898721 A US 3898721A
- Authority
- US
- United States
- Prior art keywords
- stack
- top cap
- firing
- cap
- temperature
- 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
- 238000009792 diffusion process Methods 0.000 title claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 23
- 238000010304 firing Methods 0.000 claims abstract description 15
- 238000004140 cleaning Methods 0.000 claims abstract description 7
- 238000004519 manufacturing process Methods 0.000 claims abstract description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 12
- 229910052759 nickel Inorganic materials 0.000 claims description 6
- 229910000990 Ni alloy Inorganic materials 0.000 claims description 5
- 239000000356 contaminant Substances 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 6
- 238000005238 degreasing Methods 0.000 abstract description 4
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 4
- 239000001257 hydrogen Substances 0.000 abstract description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 3
- 238000005406 washing Methods 0.000 abstract description 3
- 239000000463 material Substances 0.000 description 3
- 239000010406 cathode material Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 241000237519 Bivalvia Species 0.000 description 1
- 235000020639 clam Nutrition 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004506 ultrasonic cleaning Methods 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 method com prises thoroughly cleaning the stack and cap such as 1 References Cited by degreasing and water washing and then fitting the UNITED STATES PATENTS cap to the stack and firing first in air at a temperature 2,708,249 5/1955 Pryslak 29/25.16 X of about 500600C and then in hydrogen at a tem 3 5. 75 3 9 3 Knauf, Jr 313 270 perature of at least 1,100C whereby a diffusion bond 3,214,626 10/1965 Larson 313/270 is formed between the cap and the stack. 3,333,141 7/1967 Lemmens et al].
- cathodes for electron discharge devices and more particularly to cathodes for cathode ray tubes.
- Such cathodes generally comprise a hollow tubular stack or body portion having a cupshaped top cap bonded or otherwise affixed to one end thereof.
- it has been the practice to weld the top cap to the stack in one or more places. While this procedure has worked well for many years it is costly and time consuming and introduces other problems as well.
- Yet another object of the invention is the provision of a method of attaching top caps to stacks which method does not utilize welding and which introduces no uneven spots or protrusions or weld contamination into the cathode assembly.
- the top cap is fitted over one end of the stack, preferably under pressure of about pounds.
- the now assembled cap and stack are then first fired in air to oxidize any volatile contaminants thereon and then second fired in a reducing atmosphere, generally hydrogen, at a temperature sufficiently high to form a diffusion bond between the top cap and the stack. While the oxidizing firing can take place at a temperature of about 500-600C the final or second firing in the reducing atmosphere should be accomplished at a temperature of about 1,100C for at least one minute. Under these conditions the top cap is firmly bonded to the stack as by a diffusion bond.
- a reducing atmosphere generally hydrogen
- FIG. 1 is an elevational view of a cathode, with parts broken away which can be fabricated by this method.
- FIG. 2 is a flow diagram of the basic process of this invention.
- FIG. 1 there is shown a cathode assembly 10 which is comprised of a hollow tubular stack 12 and a top cap 14 bonded thereto.
- the top cap 14 is generally cup-shaped and fits tightly over one end of stack 12. It will be observed from a study of the figure that no additional bonding material is utilized between the two pieces. Only a tight fit and a high firing temperature are necessary to achieve a thermal diffusion bond.
- Both the stack and top cap are formulated or fabricated from more or less conventional cathode materials: that is, nickel or nickel alloys containing at least about nickel. The process works well with all known cathode materials.
- the method is accomplished by first forming the stack by any known tubular forming technique; and the top cap also is fabricated by any known techniques such as die drawing. After the stack and cap are formed they are cleaned, as by degreasing to remove any organic contaminating materials and can then be water washed to remove any salts that may be thereon. Ultrasonic cleaning is also a desirable cleaning technique. After cleaning, the cap is fitted to the stack, and a tight fit is preferable. Such a tight fit, of course, is accomplished by fabricating the internal diameter of the top cap so that it is the same as or only slightly larger than the outside diameter of the stack.
- the cap and stack are fitted together they are first fired in air to oxidize any volatile contaminants that may have been picked up and this firing is accomplished at a temperature of about 500600C.
- the cathode assembly is fired in a reducing atmosphere such as hydrogen at a temperature sufficiently high to form a diffusion bond between the top cap and the stack.
- the temperature of this firing should be about 1,100C for at least one minute and preferably about 3 minutes.
- the cathode is ready to have emissive material applied thereto.
- a method of fabricating cathodes for electron discharge devices comprising a hollow tubular stack and a substantially cup-shaped top cap fitted over one end of said stack and affixed thereto, said method comprising the steps of: forming said tubular stack from a nickel alloy containing at least about 95% nickel; forming said top cap from a nickel alloy containing at least about 95% nickel; said top cap having an internal diameter just large enough to fit over the external diameter of said stack; cleaning said stack and said top cap; drying said stack and top cap; fitting said top cap onto said stack to form a cathode assembly; firing said assembly in air to oxidize any volatile contaminants thereon at a temperature of above about 500600C; and firing said assembly in a reducing atmosphere at a temperature sufficiently high to form a diffusion bond between said top cap and said stack, said cathode assembly reaching a temperature of about 1,100C for at least one minute during said firing in said reducing atmosphere.
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
Abstract
A method of fabricating cathodes for electron discharge devices wherein the cathodes comprise a hollow tubular stack and a substantially cup-shaped top cap fitted over one end of the stack. The method comprises thoroughly cleaning the stack and cap such as by degreasing and water washing and then fitting the cap to the stack and firing first in air at a temperature of about 500-600*C and then in hydrogen at a temperature of at least 1,100*C whereby a diffusion bond is formed between the cap and the stack.
Description
United States Patent Decker et a1.
1451 Aug. 12, 1975 1 DIFFUSION BONDED CATHODE FOR OTHER PUBLICATIONS ELECTRON DISCHARGE DEVICE B. R. Garrett et 211., Broad Applleatlons of Diffusion [751 Inventors: John J. Decker; Donald Bonding," NASA CR409, March 1966, pp. 19-26.
Kerstetter, both of Emporium, Pa.
[73] Assignee: GTE Sylvania Incorporated, Primary ExaminerRoy Lake Stamford, Conn. Assistant ExaminerJames W. Davie 1 Attorne A em, or FirmNorman J. OMalle [22] May 18,1973 Wi11iam 1-L 1V1cNei1hDona1d R. Castle y [21] Appl. No.: 361,830
[57] ABSTRACT [52] US. Cl. 29/25.l4; 29/494; 313/270 A method of fabricating cathodes f electron [51] Int. Cl? I-IOIJ 9/00; 1323K 31/02 charge devices wherein the cathodes comprise a 1 [58] Field of Search 29/25.13, 25.14, 191, 484, 1 tubular Stack and a Substantially cup shaped top 29/498 488, 494; 313/270 cap fitted over one end of the stack. The method com prises thoroughly cleaning the stack and cap such as 1 References Cited by degreasing and water washing and then fitting the UNITED STATES PATENTS cap to the stack and firing first in air at a temperature 2,708,249 5/1955 Pryslak 29/25.16 X of about 500600C and then in hydrogen at a tem 3 5. 75 3 9 3 Knauf, Jr 313 270 perature of at least 1,100C whereby a diffusion bond 3,214,626 10/1965 Larson 313/270 is formed between the cap and the stack. 3,333,141 7/1967 Lemmens et al..... 313/346 R 3,667,110 6/1972 Gwyn, Jr 29/488 x 2 Clams, 2 Drawlng Flgul'es FORM 5 TACK FORM TOP CAP DEGREA SE WATER WASH FIRE IN AIR FIRE IN H PATENTEB AUG 1 2 I975 FORM STACK FORM TOP CAP DEGREASE WATER WASH FIT CAP TO STACK FIRE IN AIR FIRE IN H ji 9. a
DIFFUSION BONDED CATHODE FOR ELECTRON DISCHARGE DEVICE BACKGROUND OF THE INVENTION This invention relates to cathodes for electron discharge devices and more particularly to cathodes for cathode ray tubes. Such cathodes generally comprise a hollow tubular stack or body portion having a cupshaped top cap bonded or otherwise affixed to one end thereof. In the past it has been the practice to weld the top cap to the stack in one or more places. While this procedure has worked well for many years it is costly and time consuming and introduces other problems as well. One of the major ones of these problems is the fact that the weld between a wall of the top cap and the stack is seldom smooth, and often introduces burrs or protrusions which can subsequently break off during tube operation. Furthermore, with the current trend toward high voltage operation in cathode ray tubes any protrusions or unevenness formed on the cathode makes it very subject to disruptive arcs.
Therefore, it would be very advantageous if a method of bonding a top cap to the stack could be found which obviated the above-cited disadvantages.
OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, an object of this invention to obviate the above-cited disadvantages of the prior art method.
It is another object of the invention to enhance the fabrication of electron discharge device cathodes.
Yet another object of the invention is the provision of a method of attaching top caps to stacks which method does not utilize welding and which introduces no uneven spots or protrusions or weld contamination into the cathode assembly.
These objects are achieved in one aspect of the in vention by the provision ofa method which utilizes diffusion bonding of the top cap to the stack. To achieve this method it is necessary that the parts; i.e., the top cap and the stack be extremely clean. This can be achieved by first degreasing the cathode top cap and stack and can also include washing in water to remove any contaminating salts. Also, a high degree of precision in the fitting of the parts is required. This degree of precision is accomplished by having the internal diameter of the top cap the same as or just slightly larger than the outside diameter of the stack.
After cleaning, the top cap is fitted over one end of the stack, preferably under pressure of about pounds. The now assembled cap and stack are then first fired in air to oxidize any volatile contaminants thereon and then second fired in a reducing atmosphere, generally hydrogen, at a temperature sufficiently high to form a diffusion bond between the top cap and the stack. While the oxidizing firing can take place at a temperature of about 500-600C the final or second firing in the reducing atmosphere should be accomplished at a temperature of about 1,100C for at least one minute. Under these conditions the top cap is firmly bonded to the stack as by a diffusion bond.
The phenomenon being exhibited by this method has long been known to exist. That is, high temperature firing of super cleanparts has generally resulted in a number of the parts sticking together. However, this in the past has always been a troublesome aspect of the firing procedures and it is believed that this is the first known practical use of the phenomenon.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of a cathode, with parts broken away which can be fabricated by this method.
FIG. 2 is a flow diagram of the basic process of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in conjunction with the above-described drawings.
Referring now to the drawings with greater particularity, in FIG. 1 there is shown a cathode assembly 10 which is comprised of a hollow tubular stack 12 and a top cap 14 bonded thereto. The top cap 14 is generally cup-shaped and fits tightly over one end of stack 12. It will be observed from a study of the figure that no additional bonding material is utilized between the two pieces. Only a tight fit and a high firing temperature are necessary to achieve a thermal diffusion bond.
Both the stack and top cap are formulated or fabricated from more or less conventional cathode materials: that is, nickel or nickel alloys containing at least about nickel. The process works well with all known cathode materials.
The method is accomplished by first forming the stack by any known tubular forming technique; and the top cap also is fabricated by any known techniques such as die drawing. After the stack and cap are formed they are cleaned, as by degreasing to remove any organic contaminating materials and can then be water washed to remove any salts that may be thereon. Ultrasonic cleaning is also a desirable cleaning technique. After cleaning, the cap is fitted to the stack, and a tight fit is preferable. Such a tight fit, of course, is accomplished by fabricating the internal diameter of the top cap so that it is the same as or only slightly larger than the outside diameter of the stack. After the cap and stack are fitted together they are first fired in air to oxidize any volatile contaminants that may have been picked up and this firing is accomplished at a temperature of about 500600C. After the oxidizing firing the cathode assembly is fired in a reducing atmosphere such as hydrogen at a temperature sufficiently high to form a diffusion bond between the top cap and the stack. The temperature of this firing should be about 1,100C for at least one minute and preferably about 3 minutes. After the final firing it is found that the top cap is diffusion bonded to the stack in an extremely clean manner wherein no protrusions or burrs have been introduced.
At this stage the cathode is ready to have emissive material applied thereto.
It will be seen from the above that use of this process provides a very novel method of fabricating cathodes which is simple and inexpensive and eliminates the necessity of welding the top cap to the stack. It is very readily automated and produces extremely clean cathodes that can be operated in tubes employing extremely high anode voltages; that is, in the neighborhood of 30,000 volts, without causing noticeable arcing.
While there has been shown and described what is at present considered the preferred embodiment of the invention, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined by the appended claims.
What is claimed is:
1. A method of fabricating cathodes for electron discharge devices, said cathodes comprising a hollow tubular stack and a substantially cup-shaped top cap fitted over one end of said stack and affixed thereto, said method comprising the steps of: forming said tubular stack from a nickel alloy containing at least about 95% nickel; forming said top cap from a nickel alloy containing at least about 95% nickel; said top cap having an internal diameter just large enough to fit over the external diameter of said stack; cleaning said stack and said top cap; drying said stack and top cap; fitting said top cap onto said stack to form a cathode assembly; firing said assembly in air to oxidize any volatile contaminants thereon at a temperature of above about 500600C; and firing said assembly in a reducing atmosphere at a temperature sufficiently high to form a diffusion bond between said top cap and said stack, said cathode assembly reaching a temperature of about 1,100C for at least one minute during said firing in said reducing atmosphere.
2. The method of claim 1 wherein said top cap is fitted to said stack with a pressure of about 15 pounds.
Claims (2)
1. A METHOD OF FABRICATING CATHODES FOR ELECTRON DISCHARGE DEVICES, SAID CATHODES COMPRISING A HOLLOW TUBULAR STACK AND A SUBSTANTIALLY CUP-SHAPED TOP CAP FITTED OVER ONE END OF SAID STACK AND AFFIXED THERETO, SAID METHOD COMPRISING THE STEPS OF: FORMING SAID TUBULAR STACK FROM A NICKEL ALLOY CONTAINING AT LEAST ABOUT 95% NICKEL, FORMING SAID TOP CAP FROM A NICKEL ALLOY CONTAINING AT LEAST ABOUT 95% NICKEL, SAID TOP CAP HAVING AN INTERNAL DIAMETER JUST LARGE ENOUGH TO FIT OVER THE EXTERNAL DIAMETER OF SAID STACK, CLEANING SAID STACK AND SAID TOP CAP, DRYING SAID STACK AND TOP CAP, FITTING SAID TOP CAP ONTO SAID STACK TO FORM A CATHODE ASSEMBLY, FIRING SAID ASSEMBLY IN AIR TO OXIDIZE ANY VOLATILE CONTAMINANTS THEREON AT A TEMPERATURE OF ABOVE ABOUT 500*-600*C, AND FIRING SAID ASSEMBLY IN A REDUCING ATMOSPHERE AT A TEMPERATURE SUFFICIENTLY HIGH TO FORM A DIFFUSION BOND BETWEEN SAID TOP CAP AND SAID STACK, SAID CATHODE ASSEMBLY REACHING A TEMPERATURE OF ABOUT 1,100*C FOR AT LEAST ONE MINUTE DURING SAID FIRING IN SAID REDUCING ATMOSPHERE.
2. The method of claim 1 wherein said top cap is fitted to said stack with a pressure of about 15 pounds.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US361830A US3898721A (en) | 1973-05-18 | 1973-05-18 | Diffusion bonded cathode for electron discharge device |
| BE143854A BE814472A (en) | 1973-05-18 | 1974-05-02 | PROCESS FOR MANUFACTURING CATHODES FOR ELECTRONIC DISCHARGE DEVICES AND PRODUCTS THUS OBTAINED |
| DE19742462749 DE2462749B1 (en) | 1973-05-18 | 1974-05-15 | Process for the production of a cathode for electron discharge tubes |
| DE19742423524 DE2423524C3 (en) | 1973-05-18 | 1974-05-15 | Method of manufacturing a cathode for electron discharge tubes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US361830A US3898721A (en) | 1973-05-18 | 1973-05-18 | Diffusion bonded cathode for electron discharge device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3898721A true US3898721A (en) | 1975-08-12 |
Family
ID=23423604
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US361830A Expired - Lifetime US3898721A (en) | 1973-05-18 | 1973-05-18 | Diffusion bonded cathode for electron discharge device |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US3898721A (en) |
| BE (1) | BE814472A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0262815A1 (en) * | 1986-09-27 | 1988-04-06 | THORN EMI plc | Hydrogen getter and method of manufacture |
| US5013965A (en) * | 1988-11-02 | 1991-05-07 | Samsung Electron Devices Co., Ltd. | Electron gun cathode and manufacturing method therefor |
| NL9201450A (en) * | 1991-10-24 | 1993-05-17 | Samsung Electronic Devices | METHOD FOR MANUFACTURING AN IMPREGNATED CATHODIC STRUCTURE |
| US5433640A (en) * | 1993-02-09 | 1995-07-18 | Litton Systems, Inc. | Method for improving spectrum quality of low power pulsed anode magnetrons |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2708249A (en) * | 1950-12-05 | 1955-05-10 | Rca Corp | Ultra high frequency electron tube |
| US3085175A (en) * | 1960-03-14 | 1963-04-09 | Rca Corp | Cathode assembly for electron tube |
| US3214626A (en) * | 1961-12-11 | 1965-10-26 | Rca Corp | Cathode assembly for electron tube |
| US3333141A (en) * | 1961-03-08 | 1967-07-25 | Philips Corp | Double layer oxide cathode with reducing agent |
| US3667110A (en) * | 1969-11-03 | 1972-06-06 | Contacts Inc | Bonding metals without brazing alloys |
-
1973
- 1973-05-18 US US361830A patent/US3898721A/en not_active Expired - Lifetime
-
1974
- 1974-05-02 BE BE143854A patent/BE814472A/en unknown
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2708249A (en) * | 1950-12-05 | 1955-05-10 | Rca Corp | Ultra high frequency electron tube |
| US3085175A (en) * | 1960-03-14 | 1963-04-09 | Rca Corp | Cathode assembly for electron tube |
| US3333141A (en) * | 1961-03-08 | 1967-07-25 | Philips Corp | Double layer oxide cathode with reducing agent |
| US3214626A (en) * | 1961-12-11 | 1965-10-26 | Rca Corp | Cathode assembly for electron tube |
| US3667110A (en) * | 1969-11-03 | 1972-06-06 | Contacts Inc | Bonding metals without brazing alloys |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0262815A1 (en) * | 1986-09-27 | 1988-04-06 | THORN EMI plc | Hydrogen getter and method of manufacture |
| US5013965A (en) * | 1988-11-02 | 1991-05-07 | Samsung Electron Devices Co., Ltd. | Electron gun cathode and manufacturing method therefor |
| NL9201450A (en) * | 1991-10-24 | 1993-05-17 | Samsung Electronic Devices | METHOD FOR MANUFACTURING AN IMPREGNATED CATHODIC STRUCTURE |
| US5433640A (en) * | 1993-02-09 | 1995-07-18 | Litton Systems, Inc. | Method for improving spectrum quality of low power pulsed anode magnetrons |
Also Published As
| Publication number | Publication date |
|---|---|
| BE814472A (en) | 1974-09-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3531853A (en) | Method of making a ceramic-to-metal seal | |
| US2698913A (en) | Cathode structure | |
| US2411184A (en) | Fabrication of discharge devices | |
| US2673277A (en) | Incandescible cathode and method of making the same | |
| JPH06310086A (en) | Photomultiplier | |
| US5442255A (en) | Electron emitting device | |
| US3898721A (en) | Diffusion bonded cathode for electron discharge device | |
| US2233917A (en) | Black coating for electron discharge devices | |
| US3875629A (en) | Method of fabricating cathodes for electron discharge devices | |
| US3846006A (en) | Method of manufacturing of x-ray tube having thoriated tungsten filament | |
| US3666343A (en) | Method of applying a radiation shield to a second anode button | |
| US3853374A (en) | Method for the manufacture of photoelectron multipliers | |
| US3163793A (en) | Electron discharge device having a stand-by cathode | |
| US3524098A (en) | Aluminum anode power tube | |
| US2070691A (en) | Electron discharge device | |
| US2400635A (en) | Method of making tubes | |
| US3720985A (en) | Method of improving adherence of emissive material in thermionic cathodes | |
| US1821238A (en) | Rectifier | |
| US1861637A (en) | Production of alkali metal tubes | |
| US3233954A (en) | Method of manufacturing cathoderay tubes | |
| KR920004896B1 (en) | Impregnated cathode and its manufacturing method | |
| US6139388A (en) | Method of forming a frit seal between a stem and a neck of a cathode ray tube during manufacturing of a cathode ray tube | |
| GB1583585A (en) | Dispenser cathode | |
| US1957486A (en) | Electron emitter | |
| US2441260A (en) | Electrode |