EP0034512A2 - Heizungselement für indirekt geheizte Kathoden, Herstellungsverfahren eines solchen Elements und indirekt geheizte Kathode, die solch ein Element enthält - Google Patents

Heizungselement für indirekt geheizte Kathoden, Herstellungsverfahren eines solchen Elements und indirekt geheizte Kathode, die solch ein Element enthält Download PDF

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Publication number
EP0034512A2
EP0034512A2 EP81400096A EP81400096A EP0034512A2 EP 0034512 A2 EP0034512 A2 EP 0034512A2 EP 81400096 A EP81400096 A EP 81400096A EP 81400096 A EP81400096 A EP 81400096A EP 0034512 A2 EP0034512 A2 EP 0034512A2
Authority
EP
European Patent Office
Prior art keywords
alumina
mixture
heating element
cylinder
oxide
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Withdrawn
Application number
EP81400096A
Other languages
English (en)
French (fr)
Other versions
EP0034512A3 (de
Inventor
Arvind Shroff
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
Original Assignee
Thomson CSF SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0034512A2 publication Critical patent/EP0034512A2/de
Publication of EP0034512A3 publication Critical patent/EP0034512A3/de
Withdrawn legal-status Critical Current

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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
    • H01J1/24—Insulating layer or body located between heater and emissive material

Definitions

  • the present invention relates to a heating element for an indirectly heated cathode. It also relates to a method of manufacturing such an element and to indirectly heated cathodes comprising such an element.
  • Indirectly heated cathodes which are used in electronic tubes are well known in the prior art. They generally consist of an emissive disc brazed at one of the ends of a cylinder of non-emissive material which serves as a housing. Inside the cylinder is placed a filament which ensures the so-called indirect heating of the cathode.
  • the filament In cathodes with indirect heating by "potted” filament, the filament is less vulnerable to shocks and mechanical vibrations than in cathodes with indirect heating by free filament.
  • the present invention relates to cathodes with indirect heating by "potted" filament.
  • the "potting" consists of a mixture of alumina and of less than 10% by weight of an oxide of one of the elements of column III A of the periodic table of the elements, this mixture being sintered between 1700 and 1800 ° C.
  • the mixture consists of yttrium oxide and alumina of chemical composition 3 Y 2 O 3 . 5 Al 2 O 3 , plus alumina in the ⁇ phase
  • FIG. 1 represents a perspective view of an indirect heating cathode with potted filament.
  • This cathode consists of an emissive disc 1 which occupies one of the ends of a cylinder 2 made of non-emissive material.
  • the cylinder 2 is generally made of molybdenum. It serves as a housing for the cathode and is also called the "skirt" of the cathode.
  • a porous entungsten disc 1 is brazed. Brazing takes place around 1900 ° C.
  • a filament 3 made of tungsten or tungsten is introduced into the cylinder.
  • potting 4 which blocks the filament 3 in the cylinder.
  • the "potting" consists of a mixture of alumina and of less than 10% by weight of an oxide of one of the elements of column III A of the periodic table of the elements, this mixture being sintered between 1700 and 1800 ° C.
  • FIG. 2 shows a detail of the phase diagram of the alumina-yttrium oxide mixture, which is taken from the work: "Phase diagrams for Ceramists - 1969 - supplement”.
  • the thick line curve indicates the melting tempera- ture of the mixture of alumina Al 2 O 3, yttrium oxide Y 2 0 3 based on the percentages by weight of alumina and yttria.
  • This curve is discontinuous. For certain percentages of alumina and yttrium oxide, melting occurs at a lower temperature than for the other percentages, they are eutectic compositions.
  • the alumina-yttrium oxide mixture is a eutectic is interesting because it makes it possible to reduce the temperature of the sintering compared to pure alumina.
  • the chemical composition of the solid product obtained is the same over a wide range of the respective percentages of alumina and yttrium oxide. Indeed, it is difficult when making a mixture of powders - here alumina powder and yttrium oxide powder - to ensure that the mixture is perfectly well produced and that the percentage of bodies present is constant. Consequently, it is advantageous to obtain the same chemical compound even if the mixture is not perfectly homogeneous.
  • the alumina which enters into the composition of the "potting" can consist of several varieties of alumina of different particle size.
  • grains less than 10 ⁇ m in diameter and gains of 10 to 50 ⁇ m in diameter are used.
  • the "potting" can be carried out by sintering between 1700 and 1800 ° C. a mixture of alumina and less than 10% of a scandium oxide, lanthanum or actinium.
  • the chemical composition of the bodies obtained will be, in the case of lanthanum oxide, La 2 O 3 . 11 Al 2 O 3 plus alumina in the ⁇ phase and in the case of scandium oxide, Sc 2 O 3 . Al 2 03, plus alumina in the ⁇ phase.
  • the insulation layer deposited by cataphoresis on the filament 3 may be an alumina layer as has been indicated in the description of FIG. 1, but this insulation layer may also have the same composition as the mixture which is used for potting, for example alumina and yttrium oxide.
  • alumina powder firstly intimately mixing, with stirring for at least 24 hours, powder of an oxide of one of the elements of column III A of the periodic table of the elements and one or more alumina powders different particle size.
  • the alumina powder should not exceed 10% by weight of the mixture.
  • a binder is then added to the mixture so as to obtain a paste.
  • the face of the emissive disc 1 which is situated towards the inside of the cylinder 2 is coated with this paste 5. This step is shown in FIG. 3a.
  • the binder is slowly evaporated using an electric lamp, for example 100 W, or leaving to dry naturally.
  • the filament 3 is introduced into the cylinder 2. This step is shown in FIG. 3b.
  • the cylinder is then filled several times with the paste, the consistency of which can be modified by adding the binder.
  • the binder which may be acetone, is evaporated using the electric lamp.

Landscapes

  • Solid Thermionic Cathode (AREA)
  • Powder Metallurgy (AREA)
EP81400096A 1980-02-15 1981-01-23 Heizungselement für indirekt geheizte Kathoden, Herstellungsverfahren eines solchen Elements und indirekt geheizte Kathode, die solch ein Element enthält Withdrawn EP0034512A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8003410 1980-02-15
FR8003410A FR2476386A1 (fr) 1980-02-15 1980-02-15 Element chauffant pour cathode a chauffage indirect, procede de fabrication d'un tel element et cathode a chauffage indirect comportant un tel element

Publications (2)

Publication Number Publication Date
EP0034512A2 true EP0034512A2 (de) 1981-08-26
EP0034512A3 EP0034512A3 (de) 1982-05-26

Family

ID=9238641

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81400096A Withdrawn EP0034512A3 (de) 1980-02-15 1981-01-23 Heizungselement für indirekt geheizte Kathoden, Herstellungsverfahren eines solchen Elements und indirekt geheizte Kathode, die solch ein Element enthält

Country Status (3)

Country Link
US (1) US4427916A (de)
EP (1) EP0034512A3 (de)
FR (1) FR2476386A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2664427A1 (fr) * 1990-07-03 1992-01-10 Thomson Tubes Electroniques Cathode a chauffage indirect a filament integre pour tube a faisceau lineaire.
WO2001015206A1 (de) * 1999-08-22 2001-03-01 Ip2H Ag Lichtquelle

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60189447U (ja) * 1984-05-28 1985-12-16 アップリカ葛西株式会社 自動車用子供安全シ−ト
JPH0624093B2 (ja) * 1984-12-26 1994-03-30 株式会社日立製作所 傍熱型陰極用ヒ−タ
US5065070A (en) * 1990-12-21 1991-11-12 Hughes Aircraft Company Sputtered scandate coatings for dispenser cathodes
US5208508A (en) * 1991-09-16 1993-05-04 Raytheon Company Cathode heater potting assembly
FR2681726A1 (fr) * 1991-09-20 1993-03-26 Thomson Tubes Electroniques Potting isolant pour cathodes a chauffage indirect.
CN112490098B (zh) * 2020-12-09 2023-03-14 成都国光电气股份有限公司 一种热丝组件用混合填充粉料及其制备方法

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1107308B (de) 1955-07-02 1961-05-25 Philips Patentverwaltung Verfahren zur Herstellung mechanisch widerstandsfaehiger, hochisolierender Schichten auf Metallkoerpern
US2975078A (en) 1957-10-21 1961-03-14 Cons Electrodynamics Corp Ceramic coated wire
FR1315581A (fr) * 1961-02-24 1963-01-18 Siemens Ag Procédé pour fabriquer des corps frittés isolants tenant le vide
US3400294A (en) * 1964-12-07 1968-09-03 Gen Electric Heated cathode and method of manufacture
GB1133333A (en) 1965-01-29 1968-11-13 Wilkinson Sword Ltd Improvements in and relating to electrically insulating coatings
JPS495262A (de) * 1972-04-28 1974-01-17
JPS52776B2 (de) 1973-09-12 1977-01-10
US4181532A (en) 1975-10-22 1980-01-01 United Kingdom Atomic Energy Authority Production of colloidal dispersions
US4150318A (en) 1978-04-17 1979-04-17 Gte Sylvania Incorporated Low mass, indirectly heated, fast warm-up heater-cathode assembly
JPS5575967A (en) 1978-11-28 1980-06-07 Ngk Spark Plug Co Manufacture of alumina sintered body
FR2461341A1 (fr) 1979-07-12 1981-01-30 Commissariat Energie Atomique Cable electrique conducteur, insensible aux rayonnements nucleaires

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2664427A1 (fr) * 1990-07-03 1992-01-10 Thomson Tubes Electroniques Cathode a chauffage indirect a filament integre pour tube a faisceau lineaire.
WO2001015206A1 (de) * 1999-08-22 2001-03-01 Ip2H Ag Lichtquelle
US6777859B1 (en) 1999-08-22 2004-08-17 Ip2H Ag Light source

Also Published As

Publication number Publication date
FR2476386A1 (fr) 1981-08-21
US4427916A (en) 1984-01-24
EP0034512A3 (de) 1982-05-26
FR2476386B1 (de) 1982-08-20

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Inventor name: SHROFF, ARVIND