US2663069A - Method of making incandescent cathodes - Google Patents

Method of making incandescent cathodes Download PDF

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Publication number
US2663069A
US2663069A US237695A US23769551A US2663069A US 2663069 A US2663069 A US 2663069A US 237695 A US237695 A US 237695A US 23769551 A US23769551 A US 23769551A US 2663069 A US2663069 A US 2663069A
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United States
Prior art keywords
temperature
cathode
forming
internal cavity
tungsten
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
Application number
US237695A
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English (en)
Inventor
George A Espersen
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Philips Laboratories Inc
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Philips Laboratories Inc
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Filing date
Publication date
Priority to NL80924D priority Critical patent/NL80924C/xx
Priority to BE512939D priority patent/BE512939A/xx
Priority to US237695A priority patent/US2663069A/en
Application filed by Philips Laboratories Inc filed Critical Philips Laboratories Inc
Priority to DEN5805A priority patent/DE927520C/de
Priority to GB18101/52A priority patent/GB713140A/en
Priority to ES0204578A priority patent/ES204578A1/es
Priority to CH310624D priority patent/CH310624A/de
Priority to FR1060401D priority patent/FR1060401A/fr
Application granted granted Critical
Publication of US2663069A publication Critical patent/US2663069A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12014—All metal or with adjacent metals having metal particles
    • Y10T428/12028—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12014—All metal or with adjacent metals having metal particles
    • Y10T428/12028—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
    • Y10T428/12146—Nonmetal particles in a component

Definitions

  • cathodes where it is essential to make a tight joint between a porous member of refractory metal and a second member of refractory metal which members form a cavity containing an electron emissive material.
  • Cathodes described in the above-mentioned patent comprise a structure enclosing a cavity containing a supply of electron emissive material which structure has a porous wall portion of sintered refractory material, such as tungsten,
  • this porous portion must form the largest passageways connecting the cavity to the outside of the cathode and as such pores are of extremely small size, it is essential that a very tight joint be made between the porous por- 5 tion and the remaining part of the cathode structure.
  • the main object of my invention is to produce a tight joint in such cathode structures.
  • a further object is to provide a simple and inexpensive method of producing such a joint.
  • a still further object is to produce a joint which remains tight during the operation of the cathode and may even increase in tightness with increasing operating temperatures.
  • Another object is to produce a tight joint without deleteriously affecting the electron emissive material present in the cavity.
  • I form the porous body by pressing into the desired shape a mass of particles of refractory metal, such as tungsten and then heat the soformed body at a temperature which is sufficiently high to give the body good mechanical strength.
  • This body which will be referred to as the presintered body, will usually be sufficiently accurately dimensioned so as to fit with a snug fit, the body with which the tight joint is to be made.
  • the presintered porous body is then slipped over the second body which has a' higher volumetric coefficient of expansion than the refrac-- tory material to form a cathode assembly having a cavity in which the electron emissive material is provided.
  • the cathode assembly is then heated at a temperature higher than the first temperature to produce a shrinking action in the porous body and a tight shrunken joint, because the second body will expand to a greater extent than the refractory material.
  • the temperatures to be used depend upon several factors including the refractory material used, the size of the particles and the pressures used.
  • a temperature which gives the body good mechanical strength and at the same time is considerably below that temperature to be used in the second heating operation.
  • the temperature used during the second heating operation should be below that temperature at which the electron-emissive material would be deleteriously affected i. e. below its melting point, and at the same time should be sufficiently above the temperature first used to produce the necessary degree of shrinkage action and thus a tight seal. Care must, of course, be taken that the temperature used during the second operation is not so high as to produce an excessive shrinkage action which might tend to crack the porous body.
  • an inert atmosphere such as helium or argon
  • a slightly reducing atmosphere such as nitrogen containing a few percent of hydrogen.
  • Figure 1 is a sectional side view on an enlarged scale of a dispenser type cathode of the cylindrical type
  • Figure 2' is a sectionized side view of a dispenser type cathode of the end emissive type.
  • the cathode shown in Figure 1 which is particularly useful in magnetrons, comprises a tubular member I of refractory metal, for instance molybdenum, provided with a groove 2 containing a supply of electron emissive material 3, such as barium and strontium carbonates. Fitting upon the member l with a shrunken fit is a porous tubular body of sintered refractory material, such as tungsten. A heating filament 5 is located within the bore of member i.
  • the body 4 is made by pressing, for instance under a pressure of about 2,000 kgJcmE a mass of finely-divided refractory metal such as tungsten in the desired form and'for --this purpose I make use of tungsten powder having a density of 54 gins/in ⁇ and comprising the following fractions in the followi'ng'proportions as determined by the elutriation testf"
  • the presintered body t is then slipped over member 9 with the "electron 'einissive material S'present inthe cavity so asto give the cathode structure shown in Figure l.
  • the -"assembleol cathode structure is then heated in'a'n inert atmosphere such'as helium or "nitrogento-sinter-body 4 with a minimum amount of reduction of alkaline earth compound and-thereby impart a shrinking-action there to s6 --that-- body 4 embraces member l with "a shrunken fit
  • the temperature mu t be below that value at-which the electron emissive material would be deleterious'ly affected.
  • The-cathodeshown in Figure 2 which is of the end-emittingtype comprises a tubular body 6 provided with a parti ion 'l dividing' the bore thereof'into two partsl l i'tting eve-met d of body twith a s hrunken fitis a'cup shaped' por ous' member 8 of refractory metalfsuchats' tungsten; Member 3 forms the upper portion off'body'fi a cavity inwhich is located'a supply 3 of electron emissiy'e material such as bar iu'rlri and strontium carbonates.
  • A' method of manufacturing a cathode of the dispenser type oomprisingthe steps of f orming particles of a refractory metal under -pres sure into a hollow body open atone end thereof, presint'ering the so-formed body at a-temperaturehigh" enough" to impart --sufiicient mechanical strength thereto to make s a 01 body self-supporting, forming a second body of a material having a higher volumetric coefficient of expansion than the refractory metal, said second body having a shape adapted to fit into the open end of said first body and forming an internal cavity therewith for containing a supply of alkaline earth metal compound, inserting said sec ond body into said first bo'dy; and heating said first and secondbodies' to a temperature higher than the temperature at which said first body was presintered to tightly close the internal cavity" by internally expanding the second body to a greater extent than the first body.
  • a method of manufacturing a cathode of the dispenser'type comprising the steps of forming particles of tungsten under pressure into a hollow body' open' at one end thereof, presinterifig-thesO-fo'rmed body at a temperature high enough to impart sufficient mechanical strength thereto to make said body self-supporting, forming a second body of a material having a higher-volumetric coefficient of expansion -than thetungstemsaid second body having a'shape adapted.
  • 31A method of manufacturing a cathode of the dispenser type comprising the steps offo'rm ing particles of tungsten under pressure'into a hollow body operrat one" end thereof; presinter ing the so-formdbody at a degreehigli enough to impart'sufficient mechanicarstrength thereto to make said bodyself-supporting forrm' ing a second body of 'molybdenum,"said second body having a shapeadapted to fit into the open end of said first body and forming an internal cavity therewith for containingasupply of alkaline earth metal compound, inserting said'second body into said'first'body; and heating said first body and second bodies to a temperature" higher than the temperature at which said first body was presintered to tightly close the internal cavity by internally expanding the second body'to a greater extent than the first body.
  • a method of manufacturing a cathode of the dispenser type comprising the steps of 'form ing particles of tungsten under pressure into a i hollow body open at one end thereof, presintering the so-formed body at a temperature high enough to impart sufficient mechanical strength thereto to make said body self-supporting, forming a second body of molybdenum, said second body having a shape adapted to fit into the open end of said first body and forming an internal cavity'therewith for containing a supply of alkaline earthmetal compound, inserting said second body into saidfirst bodyyand heating said first and second "bodies to a temperature'higher than the temperature at which said first body was presintered in an inert atmosphere to tightly'close' the internal cavity by internallyexpanding the second body 'toa greater extent than the'firstbody.-""' "5.
  • 'Amethod of manufacturing a cathode of the dispenser type comprisingthesteps of forming particles of tungsten und'er pressure into a hollow body open at one end thereof presintering'the'so 1000 C. to impart sufiicient mechanical strength thereto to make said body self-supporting, forming a second body of molybdenum, said second body having a shape adapted to fit into the open end of said first body and forming an internal cavity therewith for containing a supply of alkaline earth metal compound, inserting said second body into said first body, and heating said first and second bodies to a temperature of about 1300 to 1800 C. to tightly close the internal cavity by internally expanding the second body to a greater extent than the first body.
  • a method of manufacturing a cathode of the dispenser type comprising the steps of forming particles of tungsten under pressure of about 2000 kg./cm. into a body open at one end thereof, presintering the so-formed body at a temperature of about 900 to 1000 C., forming a second body of molybdenum, said second body having a shape adapted to fit into the open end of said first body and forming an internal cavity therewith for containing a supply of alkaline earth metal compound, inserting said second body into said first body, and heating said first and second bodies to a temperature of about 1300 to 1800 C. to tightly close the internal cavity by internally expanding the second body to a greater extent than the first body.
  • a method of manufacturing a cathode of the dispenser type comprising the steps of forming particles of tungsten into a hollow body open at one end thereof, presintering the so-formed body at a temperature of about 900 to 1000 (3., forming a second body of molybdenum, said second body having a shape adapted to fit into the open end of said first body and forming an internal cavity therewith for containing a supply of alkaline earth metal compound, inserting said second body into said first body, and heating said first and second bodies to a temperature of about 1300 to 1800 C. in an non-oxidizing atmosphere to tightly close the internal cavity by internally expanding the second body to a greater extent than the first body.
  • a method of manufacturing a cathode of the dispenser type comprising the steps of forming particles of tungsten under pressure into a hollow body open at one end thereof, presintering the soformed body at a temperature of about 900 to 1000 C. in a non-oxidizing atmosphere forming a second body of molybdenum, said second body having a shape adapted to fit into the open end of said first body and forming an internal cavity therewith for containing a supply of alkaline earth metal compound, inserting said second body into said first body, and heating said first and second bodies to a temperature of about 1300" to 1800 C. in a non-oxidizing atmosphere to tightly close the internal cavity by internally expanding the second body to a greater extent than the first body.
  • a method of manufacturing a cathode of the dispenser type comprising the steps of forming particles of tungsten under pressure into a hollow body open at one end thereof, presintering the soformed body at a temperature of about 900 to 1000 C. to impart mechanical strength thereto, forming a second body of molybdenum, said second body having a shape adapted to fit into the open end of said first body and forming an internal cavity therewith for containing a supply of alkaline earth metal compound, inserting said second body into said first body, and heating said first and second bodies to a temperature of about 1300" to 1800 C. in hydrogen to tightly close the internal cavity by internally expanding the second body to a greater extent than the first body.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid Thermionic Cathode (AREA)
  • Powder Metallurgy (AREA)
US237695A 1951-07-20 1951-07-20 Method of making incandescent cathodes Expired - Lifetime US2663069A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
NL80924D NL80924C (is") 1951-07-20
BE512939D BE512939A (is") 1951-07-20
US237695A US2663069A (en) 1951-07-20 1951-07-20 Method of making incandescent cathodes
GB18101/52A GB713140A (en) 1951-07-20 1952-07-17 Improvements in or relating to the manufacture of dispenser cathodes
DEN5805A DE927520C (de) 1951-07-20 1952-07-17 Verfahren zur Herstellung einer Vorratskathode, deren Wand zum Teil aus poroesem, hochschmelzendem Metall besteht
ES0204578A ES204578A1 (es) 1951-07-20 1952-07-17 UN MÉTODO DE FABRICACIoN DE CáTODOS DE APORTACIoN
CH310624D CH310624A (de) 1951-07-20 1952-07-18 Verfahren zur Herstellung einer Vorratskathode und nach diesem Verfahren hergestellte Vorratskathode.
FR1060401D FR1060401A (fr) 1951-07-20 1952-07-18 Cathode à réserve et son procédé de fabrication

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US237695A US2663069A (en) 1951-07-20 1951-07-20 Method of making incandescent cathodes

Publications (1)

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US2663069A true US2663069A (en) 1953-12-22

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US237695A Expired - Lifetime US2663069A (en) 1951-07-20 1951-07-20 Method of making incandescent cathodes

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US (1) US2663069A (is")
BE (1) BE512939A (is")
CH (1) CH310624A (is")
DE (1) DE927520C (is")
ES (1) ES204578A1 (is")
FR (1) FR1060401A (is")
GB (1) GB713140A (is")
NL (1) NL80924C (is")

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2830218A (en) * 1953-09-24 1958-04-08 Gen Electric Dispenser cathodes and methods of making them
US2985946A (en) * 1955-05-10 1961-05-30 Philips Corp Indirectly heated cathode
US3170081A (en) * 1962-06-05 1965-02-16 Westinghouse Electric Corp Discharge lamp electrode
US3183396A (en) * 1962-05-21 1965-05-11 Bell Telephone Labor Inc Method of manufacturing sintered cathode
US3265495A (en) * 1961-02-07 1966-08-09 Csf Method of manufacturing cathodes
US3848153A (en) * 1972-05-25 1974-11-12 Energy Sciences Inc Elongated electron-emission cathode assembly and method
US5422536A (en) * 1993-01-08 1995-06-06 Uti Corporation Thermionic cathode with continuous bimetallic wall having varying wall thickness and internal blackening
US5729084A (en) * 1993-01-08 1998-03-17 Uti Corporation Thermionic cathode with continuous bimetallic wall

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE967137C (de) * 1953-02-05 1957-10-10 Csf Verfahren zur Herstellung einer Kathode fuer elektrische Entladungsgefaesse, bei der senkrecht zur emittierenden Oberflaeche sich erstreckende Draehte einen Vorrat an Emissionsstoffen abschliessen
NL85507C (is") * 1953-12-22
US3076915A (en) * 1954-12-24 1963-02-05 Egyesuelt Izzolampa Cathode assembly and method of making same
US3018404A (en) * 1958-03-27 1962-01-23 Raytheon Co Electron tube cathodes

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1766865A (en) * 1923-04-06 1930-06-24 Gen Motors Res Corp Alloy structure

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1766865A (en) * 1923-04-06 1930-06-24 Gen Motors Res Corp Alloy structure

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2830218A (en) * 1953-09-24 1958-04-08 Gen Electric Dispenser cathodes and methods of making them
US2985946A (en) * 1955-05-10 1961-05-30 Philips Corp Indirectly heated cathode
US3265495A (en) * 1961-02-07 1966-08-09 Csf Method of manufacturing cathodes
US3183396A (en) * 1962-05-21 1965-05-11 Bell Telephone Labor Inc Method of manufacturing sintered cathode
US3170081A (en) * 1962-06-05 1965-02-16 Westinghouse Electric Corp Discharge lamp electrode
US3848153A (en) * 1972-05-25 1974-11-12 Energy Sciences Inc Elongated electron-emission cathode assembly and method
US5422536A (en) * 1993-01-08 1995-06-06 Uti Corporation Thermionic cathode with continuous bimetallic wall having varying wall thickness and internal blackening
US5729084A (en) * 1993-01-08 1998-03-17 Uti Corporation Thermionic cathode with continuous bimetallic wall

Also Published As

Publication number Publication date
DE927520C (de) 1955-05-09
ES204578A1 (es) 1953-01-01
NL80924C (is")
FR1060401A (fr) 1954-04-01
CH310624A (de) 1955-10-31
GB713140A (en) 1954-08-04
BE512939A (is")

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