EP0441698A1 - Herstellungsverfahren einer Impregnierungskathode und mittels eines solchen Verfahrens gewonnene Kathode - Google Patents

Herstellungsverfahren einer Impregnierungskathode und mittels eines solchen Verfahrens gewonnene Kathode Download PDF

Info

Publication number
EP0441698A1
EP0441698A1 EP91400272A EP91400272A EP0441698A1 EP 0441698 A1 EP0441698 A1 EP 0441698A1 EP 91400272 A EP91400272 A EP 91400272A EP 91400272 A EP91400272 A EP 91400272A EP 0441698 A1 EP0441698 A1 EP 0441698A1
Authority
EP
European Patent Office
Prior art keywords
powder
cathode
impregnated
barium
impregnated cathode
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.)
Granted
Application number
EP91400272A
Other languages
English (en)
French (fr)
Other versions
EP0441698B1 (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 Electron Devices SA
Original Assignee
Thomson Tubes Electroniques
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 Tubes Electroniques filed Critical Thomson Tubes Electroniques
Publication of EP0441698A1 publication Critical patent/EP0441698A1/de
Application granted granted Critical
Publication of EP0441698B1 publication Critical patent/EP0441698B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

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
    • H01J1/28—Dispenser-type cathodes, e.g. L-cathode
    • 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 present invention relates to a method of manufacturing an impregnated cathode and a cathode obtained by this method. It finds an application in the production of cathodes for electronic tubes and more particularly but not exclusively for cathode ray display tubes.
  • Impregnated cathodes are commonly used to provide electronic current densities of up to 1 to 2 A / cm2 continuously and more in pulses.
  • the impregnated cathodes known from the prior art consist of a porous body of refractory metal, such as pure tungsten, or else of a mixture of tungsten, either with a metal originating from the platinum mine (mixed matrix), such as known from document FR A 2 356 263, either with scandium oxide or other rare earths in low concentration (3 to 5% by weight).
  • This porous body is generally obtained by compressing a finely divided powder of the metal (or mixture of metals) using an isostatic press or a uniaxial press.
  • the compacts thus obtained are then heated under hydrogen at high temperature, in order to sinter the particles together and to increase the density of the porous body.
  • the porous body To facilitate machining of the porous body, it is infiltrated with copper or plastic, then machined to the desired shape. Subsequently, the copper or plastic is removed by dissolving in an acid or by heating.
  • the porous body of the desired shape is then brazed on a molybdenum skirt which serves to hold, on one side, the emissive patch and, on the other, a filament potted in alumina which allows the heating of the cathode .
  • a molybdenum skirt which serves to hold, on one side, the emissive patch and, on the other, a filament potted in alumina which allows the heating of the cathode .
  • the pores of the porous body can be filled with barium and calcium aluminates.
  • the body is impregnated with these aluminates, which constitute the emissive material of the finished cathode.
  • the porous body is kept in close contact with an aluminate composition brought, under a reducing atmosphere, to a temperature above its melting point. Contact is ensured, either by immersing the porous body in the aluminate, or by placing the aluminate on the porous body. At the time of fusion, the aluminate diffuses by capillarity or by flow inside the open pores and fills them. The cathode is then cleaned mechanically and chemically, in order to remove the aluminate residues which have remained stuck on the surfaces.
  • the cathode is activated, under vacuum, at a temperature at which tungsten reduces barium and calcium aluminate to release barium oxide.
  • Metallic barium is produced in areas where the aluminate is in contact with the refractory metal (pores). The metallic barium reaches the end of the pores and diffuses over the entire emissive surface where it forms with oxygen a surface monolayer which promotes electronic emissivity by lowering the work of electron output.
  • the deposition, on the emissive surface of these impregnated cathodes, of a film of osmium, iridium, ruthenium, or an alloy of these bodies, this film having a thickness of a few thousand Angstroms can improve emissivity by a factor of around 3.
  • the mixed matrix cathode, covered with a refractory metal film, is known from document FR 4 2 469 792 in the name of the applicant.
  • the method according to the present invention aims precisely to remedy these drawbacks.
  • the invention recommends an original method which provides the advantages of impregnated cathodes, but with a procedure which is substantially simplified compared to those known from the prior art.
  • the powder of tungsten or of a mixture of tungsten and of a metal of the platinum mine or of a scandium oxide or of the three materials is mixed with a powder of aluminate, barium and calcium in the desired stoichiometric proportions, then this mixture is pressed in the form of pellets and sintered, under a hydrogen atmosphere, at a temperature higher than the melting temperature of the aluminates.
  • the mixture comprises tungsten or tungsten powder and other materials as above, with barium and calcium carbonates and of alumina in the desired stoichiometric proportions.
  • This mixture is then compressed and sintered at the same temperature as above. In this way, the aluminate is formed during "in situ" sintering.
  • the emissive surface of the pellet obtained according to the method of the invention is covered with a film of osmium, iridium or rhenium to increase its emissive properties.
  • the filament is brought and potted in a conventional manner, and the cathode is activated in the same manner as above.
  • the method according to the invention makes it possible to obtain all the advantages known from the prior art of impregnated cathodes, whether they are of simple matrix (pure tungsten) or mixed, covered or not, but with simplified procedures, shorter and less expensive, with a significantly reduced number of steps compared to the prior art, which makes it possible to obtain an equal quality of finished product with less critical handling and therefore with fewer controls.
  • the method according to the invention is therefore particularly suitable for industrial production at high speed and at low cost of cathodes with high current density and with a relatively long service life, which makes it possible to envisage their use in equipment intended for wide distribution.
  • the invention therefore relates to a method of manufacturing an impregnated cathode, characterized in that an emissive pellet is produced by co-pressing and sintering a mixture of at least one powder of refractory metal with a powder of barium and calcium aluminates, or with barium and calcium carbonates added with alumina.
  • the subject of the invention is also an impregnated cathode as obtained by implementing the method which has just been defined.
  • the invention also relates to variants of impregnated cathodes which can be produced using the process which has just been defined; for example cathodes produced according to the method of the invention and then covered with a metal film of platinum mine or the like in order to increase the electronic emissivity or to lower the operating temperature while keeping the emissivity constant.
  • the subject of the invention is also variants of impregnated cathodes which can be produced on the basis of the same principle.
  • FIG. 1 we see an example of an impregnated cathode manufactured according to the method of the invention, illustrated in these main steps in this FIG. 1.
  • the emissive disc (1) is formed by pressing (c) and sintering (d), in a conventional manner, of a mixture (b), of a powder (w) of at least one refractory metal with a powder (y) barium and calcium aluminate or barium and calcium carbonates with alumina.
  • At least one of the starting powders (w) is a powder of known elements such as tungsten, molybdenum, tantalum, rhenium or the alloys containing them, or a powder of an element capable of improving the electronic emission, such as osmium, ruthenium, iridium or alloys containing at least one of these elements or, finally, a powder of scandium oxide or particles of oxides containing scandium.
  • the skirt (4) can be made integral with the assembly by a crimping (f) on the cup (3).
  • the heating filament (5) previously covered with an alumina film (not shown), can be mounted in the skirt and held in place by an alumina body (6) commonly known by the English word “potting ".
  • This "potting" operation can be done, for example, by sintering at 1800 ° C. under hydrogen from an alumina powder deposited using a suspension around the filament inside the skirt.
  • the emissive pad could be covered with a thin metallic film with a thickness of between 10 and 30,000 Angstroms, for example, the metallic material being able to be selected from the group comprising osmium, ruthenium, iridium, and the alloys containing any of these.
  • This film can be deposited by conventional means of sputtering, vacuum deposition, or any other suitable means.
  • the method according to the invention has the advantage, compared to the prior art, of being achievable with a significantly reduced number of steps, and with less critical manipulations for the quality of the product. This results in the possibility of a better production yield, simultaneously with an accelerated rate and at lower cost per part.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid Thermionic Cathode (AREA)
  • Powder Metallurgy (AREA)
EP91400272A 1990-02-09 1991-02-05 Herstellungsverfahren einer Impregnierungskathode und mittels eines solchen Verfahrens gewonnene Kathode Expired - Lifetime EP0441698B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9001518A FR2658360B1 (fr) 1990-02-09 1990-02-09 Procede de fabrication d'une cathode impregnee et cathode obtenue par ce procede.
FR9001518 1990-02-09

Publications (2)

Publication Number Publication Date
EP0441698A1 true EP0441698A1 (de) 1991-08-14
EP0441698B1 EP0441698B1 (de) 1995-09-27

Family

ID=9393533

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91400272A Expired - Lifetime EP0441698B1 (de) 1990-02-09 1991-02-05 Herstellungsverfahren einer Impregnierungskathode und mittels eines solchen Verfahrens gewonnene Kathode

Country Status (7)

Country Link
US (1) US5334085A (de)
EP (1) EP0441698B1 (de)
JP (1) JP2710700B2 (de)
CA (1) CA2035170C (de)
DE (1) DE69113290T2 (de)
FR (1) FR2658360B1 (de)
HK (1) HK34097A (de)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4234843A1 (de) * 1992-10-15 1994-04-21 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Niederdruckentladungslampe und Herstellungsverfahren für eine Niederdruckentladungslampe
JPH0850849A (ja) * 1994-05-31 1996-02-20 Nec Kansai Ltd 陰極部材およびそれを用いた電子管
KR20020068644A (ko) * 2001-02-21 2002-08-28 삼성에스디아이 주식회사 금속 음극 및 이를 구비한 방열형 음극구조체
US6771014B2 (en) * 2001-09-07 2004-08-03 The Boeing Company Cathode design
CN101992374A (zh) * 2010-10-08 2011-03-30 杭州兴达机械有限公司 减速箱体微孔修补装置及方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0028954A1 (de) * 1979-11-09 1981-05-20 Thomson-Csf Thermoionische Kathode, Verfahren zu ihrer Herstellung und Elektronenröhre mit einer solchen Kathode
EP0091161A1 (de) * 1982-04-01 1983-10-12 Koninklijke Philips Electronics N.V. Verfahren zum Herstellen einer Vorratskathode und gemäss dem Verfahren hergestellte Vorratskathode
WO1989009480A1 (en) * 1988-03-28 1989-10-05 Hughes Aircraft Company Expandable dispenser cathode
EP0409275A2 (de) * 1989-07-21 1991-01-23 Nec Corporation Herstellungsverfahren einer Kathode vom Imprägnierungstyp

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL89470C (de) * 1953-03-04
BE564257A (de) * 1957-01-26
SU528632A1 (ru) * 1975-03-24 1976-09-15 Предприятие П/Я А-1067 Способ изготовлени металлопористого прессованного катода
JPS58154131A (ja) * 1982-03-10 1983-09-13 Hitachi Ltd 含浸形陰極
JPS61128441A (ja) * 1984-11-28 1986-06-16 Toshiba Corp 含浸形陰極の製造方法
FR2596198A1 (fr) * 1986-03-19 1987-09-25 Thomson Csf Cathodes pour klystron a faisceaux multiples, klystron comportant de telles cathodes et procede de fabrication de telles cathodes
JPS63175313A (ja) * 1987-01-14 1988-07-19 Nec Corp 含浸型陰極およびその製造方法
JPS63254636A (ja) * 1987-04-10 1988-10-21 Hitachi Ltd 含浸形陰極
JPS63311082A (ja) * 1987-06-12 1988-12-19 日本鋼管株式会社 高密度焼結体の製造装置
NL8701584A (nl) * 1987-07-06 1989-02-01 Philips Nv Werkwijze voor de vervaardiging van een naleveringskathode; naleveringskathode vervaardigd volgens de werkwijze; lopende golfbuis, klystron en zendbuis bevattende een kathode vervaardigd volgens de werkwijze.
NL8902793A (nl) * 1989-11-13 1991-06-03 Philips Nv Scandaatkathode.

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0028954A1 (de) * 1979-11-09 1981-05-20 Thomson-Csf Thermoionische Kathode, Verfahren zu ihrer Herstellung und Elektronenröhre mit einer solchen Kathode
EP0091161A1 (de) * 1982-04-01 1983-10-12 Koninklijke Philips Electronics N.V. Verfahren zum Herstellen einer Vorratskathode und gemäss dem Verfahren hergestellte Vorratskathode
WO1989009480A1 (en) * 1988-03-28 1989-10-05 Hughes Aircraft Company Expandable dispenser cathode
EP0409275A2 (de) * 1989-07-21 1991-01-23 Nec Corporation Herstellungsverfahren einer Kathode vom Imprägnierungstyp

Also Published As

Publication number Publication date
DE69113290T2 (de) 1996-03-07
CA2035170A1 (fr) 1991-08-10
DE69113290D1 (de) 1995-11-02
JP2710700B2 (ja) 1998-02-10
US5334085A (en) 1994-08-02
JPH0785782A (ja) 1995-03-31
EP0441698B1 (de) 1995-09-27
HK34097A (en) 1997-03-27
FR2658360A1 (fr) 1991-08-16
CA2035170C (fr) 2001-05-29
FR2658360B1 (fr) 1996-08-14

Similar Documents

Publication Publication Date Title
US7569994B2 (en) High-load and high-intensity discharge lamp
EP0317002B1 (de) Scandatkathode
EP0441698B1 (de) Herstellungsverfahren einer Impregnierungskathode und mittels eines solchen Verfahrens gewonnene Kathode
EP0698280B1 (de) Vorratskathode und verfahren zur herstellung einer vorratskathode
EP0794548B1 (de) Thermionische Kathode und Verfahren zu ihrer Herstellung
US4291252A (en) Electron tube cathode
EP0034512A2 (de) Heizungselement für indirekt geheizte Kathoden, Herstellungsverfahren eines solchen Elements und indirekt geheizte Kathode, die solch ein Element enthält
JP2000106131A (ja) 放電灯用電極に使用されるタングステン材、放電灯用電極およびそれを用いた放電灯
CN110690086B (zh) 一种荧光灯芯柱固汞工艺
NL1009716C2 (nl) Werkwijze ter vervaardiging van een kathode-onderdeel en elektronenbuis die daarmee is uitgerust.
EP1200973B1 (de) Oxidkathode und zugehöriges herstellungsverfahren
EP1063668A2 (de) Kathodenbaugruppe und Farbkathodenstrahlröhre mit solcher Baugruppe
JP2005285587A (ja) 冷陰極管用電極及び該電極を用いた冷陰極管
FR2683090A1 (fr) Cathode a reserve et procede de fabrication d'une telle cathode.
JP3346372B2 (ja) ランプ用傾斜機能材料製封止部材
JP2007511880A (ja) 冷陰極ランプのための一体化されたゲッターと低仕事関数を有する陰極及びその製造方法
JPS60220529A (ja) 含浸カソードおよびその製造方法
FR2672425A1 (fr) Cathode de reserve pour tube electronique.
JPH07169383A (ja) 含浸型カソードおよびそれを用いた電子管または電子線応用装置
JP2001355059A (ja) 複合蒸着材およびその製造方法
FR2833406A1 (fr) Cathode pour tube a vide a duree de vie amelioree
JP2005203184A (ja) 冷陰極蛍光ランプ用電極材および放電電極、その製造方法
FR2656954A1 (fr) Cathode pour tube electronique et son procede de fabrication.
JPS63143718A (ja) 複層カソ−ドスリ−ブの製造方法
FR2716034A1 (fr) Emetteurs thermoélectroniques d'électrons et procédés pour leur fabrication.

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): CH DE FR GB IT LI NL SE

17P Request for examination filed

Effective date: 19920207

17Q First examination report despatched

Effective date: 19931130

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): CH DE FR GB IT LI NL SE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19950927

REF Corresponds to:

Ref document number: 69113290

Country of ref document: DE

Date of ref document: 19951102

ITF It: translation for a ep patent filed

Owner name: JACOBACCI & PERANI S.P.A.

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19951227

GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)

Effective date: 19951208

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19960228

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19960228

NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20090129

Year of fee payment: 19

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20090204

Year of fee payment: 19

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: IT

Payment date: 20090218

Year of fee payment: 19

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20090213

Year of fee payment: 19

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20100205

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20101029

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100301

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100901

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100205

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100205