EP1255274A2 - Procédé de fabrication d'une cathode imprégnée pour tube à rayons cathodiques - Google Patents

Procédé de fabrication d'une cathode imprégnée pour tube à rayons cathodiques Download PDF

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Publication number
EP1255274A2
EP1255274A2 EP02100425A EP02100425A EP1255274A2 EP 1255274 A2 EP1255274 A2 EP 1255274A2 EP 02100425 A EP02100425 A EP 02100425A EP 02100425 A EP02100425 A EP 02100425A EP 1255274 A2 EP1255274 A2 EP 1255274A2
Authority
EP
European Patent Office
Prior art keywords
metal
cathode
matrix
ray tube
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Withdrawn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
EP02100425A
Other languages
German (de)
English (en)
Inventor
Georg c/o Philips Corp.Intell.Prop. Gärtner
Chris c/o Philips Corp.Intell.Prop. Goodhand
Simon c/o Philips Corp.Intell.Prop. Hogson
Andrew c/o Philips Corp.Intell.Prop. Baker
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.)
Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
Original Assignee
Philips Corporate Intellectual Property GmbH
Koninklijke Philips Electronics NV
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 Philips Corporate Intellectual Property GmbH, Koninklijke Philips Electronics NV filed Critical Philips Corporate Intellectual Property GmbH
Publication of EP1255274A2 publication Critical patent/EP1255274A2/fr
Withdrawn legal-status Critical Current

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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
    • H01J9/042—Manufacture, activation of the emissive part
    • H01J9/047—Cathodes having impregnated bodies

Definitions

  • the invention relates to a method for producing a supply cathode for a Cathode ray tube, which has a cathode support with a cathode base and a porous metal matrix body that infiltrates with an electron-emitting material is included.
  • the functional groups of a cathode ray tube include an electron-emitting one Cathode that generates the electron current in the cathode ray tube.
  • An electron emitting cathode for a cathode ray tube is usually one heatable supply cathode with an electron-emitting, oxide-containing cathode body. If a supply cathode is heated, electrons are emitted from the electron Coating evaporated into the surrounding vacuum.
  • the amount of electrons that can be emitted from the cathode coating depends on the work function of the electron emitting material.
  • Nickel which is usually used as the cathode base, itself has a relatively high level Work function. Therefore, the cathode base for a supply cathode is still with one Metal matrix body, which is infiltrated with an electron-emitting material. Its main task is to control the electron-emitting properties of the cathode base to improve.
  • Characteristic of the electron emitting materials from The storage cathode is that it is an alkaline earth metal in the form of the alkaline earth metal oxide contain.
  • a correspondingly shaped metal matrix body is used for example with the carbonates of the alkaline earth metals in a binder preparation coated.
  • the carbonates are converted into the alkaline earth metal oxides at temperatures of around 1000 ° C umgswasht.
  • this cathode After this cathode has burned off, it already delivers a noticeable emission current, which, however, is not yet stable.
  • the Impurities essentially consist of elemental alkaline earth metal, e.g. B. calcium, Strontium or barium.
  • the electron emission of such supply cathodes is based on the impurity mechanism.
  • the activation process has the purpose of being sufficient Create amount of excess, elemental alkaline earth metal through which the oxides in the electron-emitting coating at a prescribed heating output can deliver maximum emission current.
  • An essential contribution to the activation process accomplishes the reduction of barium oxide to elemental barium Alloy components ("activators") made of metal matrix body.
  • the elemental alkaline earth metal is always replenished first.
  • subsequent delivery comes to a standstill if there is between the metal matrix body and a thin but high-resistance separating layer over time with the emitting oxide (interface) from alkaline earth silicate or alkaline earth aluminate.
  • No. 5,118,317 discloses a method for producing an impregnated supply cathode, which is a porous metal matrix body made of a refractory metal that acts as an activator, comprising, wherein the porous metal matrix body by compressing non-interlocking, individual powder particles made of transition metal, which with a thin layer of a ductile metal are coated, and then sintering a temperature below 600 ° C is formed.
  • Such a cathode whose metal matrix body is pressed from a metal powder and sintered has an improved emissivity and a longer life because the porous structure of the metal matrix body the surface reaction between the Activator metal and the actual emission material supported.
  • the object is achieved by a method for producing a Supply cathode for a cathode ray tube, which has a cathode support with a cathode base made of a cathode metal and a metal matrix body made of a matrix of Metal particles of a metal selected from the group of refractory metals and into the Matrix-infiltrated oxide particles of an alkaline earth oxide, selected from the group of Oxides of calcium, strontium and barium, comprising the matrix of metal particles of a metal selected from the group of refractory metals by reduction a porous, stabilized oxide gel of the metal, selected from the group of Refractory metals is produced.
  • Such a storage cathode has a uniform shape over a long period of time Beam current, because an open through the matrix by the inventive method Microstructure gets. Due to the improved surface properties, on the one hand the initial emission is already high and on the other hand the resistance to poisoning against oxygen is low. The open microstructure also increases Ba retention.
  • the cathode is not susceptible to ion bombardment and has an even emission and can be produced reproducibly. Thanks to the continuous barium tracking becomes a depletion of electron emission like that of conventional cathodes knows, avoided. It can be without endangering cathode life much higher beam current density can be realized. That can also be exploited to draw the necessary electron beam currents from smaller cathode areas.
  • the spot size of the cathode spot is crucial for the quality of the beam focusing on the screen.
  • the image sharpness over the entire screen is increased. Because the cathodes also not age, the image brightness and sharpness can be increased to a high level entire life of the tube can be kept stable.
  • This wet chemical and / or aerosol-based process is more variable, more flexible and cheaper as conventionally used powder metallurgical processes. This is mainly due at lower process temperatures below 1000 ° C compared to the sintering and Impregnation process above 1600 ° C with the conventional method.
  • the porous, stabilized Oxide gel of a refractory metal by reaction of a starting compound of the Refractory metal is produced with a microstructure control additive.
  • a block copolymer R'R "R '(OH) 2 , an emulsions, a reaction-modifying reagent and a polymer are preferably used as the microstructure control additive.
  • the metal matrix body with 20 to 80 vol% metal and 20 to 80 vol% oxide is produced Adaptations to different cathode applications in CRTs, radio frequency and Microwave tubes, X-ray tubes, thermionic converters, low and High pressure gas discharge lamps or similar possible
  • the supply cathode is characterized by robust behavior with fast switching out.
  • the invention has particularly advantageous effects over the prior art, if the porous metal matrix body with a top layer that selected a metal contains from the group Ir, Os, Re, Ru and W, by precipitation of the oxides or hydroxides of metals selected from the group Ir, Os, Re, Ru and W on the surface of the porous metal matrix and subsequent reduction to the metal is coated.
  • the porous metal matrix body coated with a top layer containing a barium calcium aluminate.
  • a cathode ray tube includes an electron gun, which is commonly contains an arrangement with one or more supply cathodes.
  • a supply cathode according to the invention comprises a cathode support with a cathode base and a porous metal matrix body.
  • the cathode support contains the heater and the base for the cathode body.
  • the material of the cathode base is usually a nickel alloy.
  • the nickel alloy for the base of the supply cathode according to the invention can be made of nickel, for example with an alloy portion selected from a reducing activator element from the group silicon, magnesium, aluminum, tungsten, molybdenum, manganese and carbon exist.
  • the metal matrix body contains infiltrated oxide particles.
  • the main component of the Oxide particles are oxide particles of an alkaline earth oxide, preferably barium oxide, together with Calcium oxide and / or strontium oxide.
  • the alkaline earth oxides are considered a physical Mixture of alkaline earth oxides or as binary or ternary mixed crystals of the alkaline earth metal oxides used. Preferred is a ternary alkaline earth mixed crystal oxide made from barium oxide, Strontium oxide and calcium oxide or a binary mixture of barium oxide and Calcium oxide.
  • the alkaline earth oxide can be doped from an oxide selected from the oxides of the Scandiums, yttriums and the lanthanoids lanthanum, cerium, praseodymium, neodymium, samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium and lutetium, e.g. in an amount of 10 to a maximum of 1000 ppm.
  • the metal matrix body further contains a matrix of metal particles of a metal selected from the group of refractory metals Mg, Al, Fe, Si, Ti, Hf, Zr, W, Mo, Mn and Cr.
  • the components of the porous metal matrix are made into a particle-particle composite arranged with open pores.
  • Particularly beneficial effects over the prior art shows a supply cathode according to the invention with a particle-particle composite, where the pore dimensions have a gradient towards the surface exhibit. Ba retention is particularly improved in this storage cathode.
  • the microstructure of the metal matrix can also be improved if the metal particles have a transition from one metal to another in a longitudinal direction.
  • the porous metal matrix can also be given a coating.
  • the porous metal matrix can be coated with a covering layer, which is one which contains metals Ir, Os, Re, Ru or W or a combination thereof.
  • This layer can by precipitation of the appropriate oxides or hydrated oxides on the surface of the Metal matrix and subsequent reduction to the metals are formed. You get thereby preferably a cover layer with a thickness of 1 to 30 microns with pores in the Submicron range.
  • the porous metal matrix can also be covered with a covering layer, the oxide particles an alkaline earth oxide selected from the group of oxides of calcium, Strontiums and bariums and oxide particles of an oxide, selected from the group of Contains oxides of scandium, yttrium and lanthanoids.
  • the oxide particles an alkaline earth oxide selected from the group of oxides of calcium, Strontiums and bariums and oxide particles of an oxide, selected from the group of Contains oxides of scandium, yttrium and lanthanoids.
  • the matrix of metal particles of a metal selected from the group of refractory metals is selected from the group of by reducing an oxide gel of the metal Made of refractory metals.
  • the refractory metals include the metals refractory metals Mg, Al, Fe, Si, Ti, Hf, Zr, W, Mo, Mn and Cr.
  • the starting chemical compounds for the metal oxide phase are used. These can be, for example, halides, carbonyls, alcoholates or metal hydroxides. For example, for the formation of a matrix of tungsten, WCl 6 , W (CO) 6 , W (OC 2 H 5 ) 6 , or H 2 WO 4 , for a matrix of nickel NiCl 4 can be used. These compounds are brought into solution, preferably into an alcoholic solution. In a homogeneous reaction, they are reacted with microstructure control additives. These microstructure control additives can be block copolymers R'R "R '(OH) 2 , emulsions eg oil-water emulsions, reaction-modifying reagents and polymers.
  • the reaction produces the corresponding oxides and oxide hydrates as gels with controlled microstructure and morphology.
  • the oxide gel is then coated with a Reducing agents, for example, reacted with 5% in nitrogen, hydrogen at 500 to 1000 ° C. in order to obtain a porous metal matrix with controlled microstructure and morphology.
  • a production method is particularly preferred in which block polymers R'R "R '(OH) 2 act as" molecular templates "which cause pseudo-sol-gel precipitation and stabilize the oxide gels.
  • the pore distribution of the oxide gel with controlled microstructure and porosity is e.g. determined by the drop characteristics in the original emulsion. Oil and others organic components of the emulsion are then subjected to a first temperature treatment removed at 400 to 600 ° C. The porous oxide gel is then reduced with a hydrogen-nitrogen mixture at 500 to 1000 ° C in a porous metal matrix with controlled microstructure and porosity.
  • microstructured porous metal matrix which is also a Gradients of the pore dimensions towards the surface or a transition to one other metal
  • either conventional infiltration, gel or a wet chemical infiltration technique is used to cover the pores of the metal matrix Replenish barium calcium aluminate or other barium oxide containing material.
  • the carbonates are used to produce the raw material for the infiltration of oxide particles of the alkaline earth metals calcium, strontium and barium ground and with each other and optionally with a starting compound for the oxide of scandium, yttrium, Lanthans, Cers, Praseodymes, Neodymes, Samariums, Europiums, Gadoliniums, Terbiums, Dysprosiums, holmiums, erbiums, thuliums, ytterbiums and lutetiums in the desired Mixed weight ratio.
  • Preferred starting compounds for the oxides of the scandium, yttrium and the lanthanoids the nitrates or hydroxides of these Elements used.
  • the weight ratio of calcium carbonate: strontium carbonate: barium carbonate is typically 1: 1.25: 6 or 1:12:22 or 1: 1.5: 2.5 or 1: 4: 6.
  • the carbonates of the alkaline earth metals Nitrates of scandium, yttrium and lanthanoids are coprecipitated.
  • the raw mass can still be mixed with a binder preparation.
  • the binder preparation can be used as solvent water, ethanol, ethyl nitrate, ethyl acetate, or Contain diethyl acetate.
  • the supply cathode is installed in the cathode ray tube.
  • the supply cathode is formed while the cathode ray tube is being evacuated.
  • the alkaline earth carbonates are converted to the alkaline earth oxides with the release of CO and CO 2 and then form a porous sintered composite.
  • Also essential in this conversion process is the crystallographic change due to mixed crystal formation, which is a prerequisite for a good supply cathode.
  • the activation takes place, which has the purpose of supplying excess elemental alkaline earth metal embedded in the oxides.
  • the excess alkaline earth metal is created by the reduction of alkaline earth metal oxide.
  • the alkaline earth oxide is reduced by the released CO or activator metal from the cathode base and from the metal matrix.
  • there is a current activation which generates the required free alkaline earth metal through electrolytic processes at high temperatures.
  • the manufacturing method according to the invention is an efficient method for composite Cathode body structures with gradients in material and structure, for example in the form of metal grid structures e.g. of Ni, porous metal matrices, e.g. B. from Tungsten or metal components containing activators for barium release. It also includes the spray deposition of complex composite cathode structures with functional gradients in conjunction with molecular self-assembly techniques based on emulsion and foaming methods. Typical examples of Structures that can be produced using the method according to the invention Sprayed storage cathode layer structures with individual Ni particle layers, storage cathodes with double layers in the metal matrix, foamed metal matrix structures, and porous metal matrix structures with controlled porosity. It is also possible, align elongated Ni particle chains via a magnetic field.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid Thermionic Cathode (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
EP02100425A 2001-05-02 2002-04-30 Procédé de fabrication d'une cathode imprégnée pour tube à rayons cathodiques Withdrawn EP1255274A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10121445 2001-05-02
DE10121445A DE10121445A1 (de) 2001-05-02 2001-05-02 Verfahren zur Herstellung einer Vorratskathode für eine Kathodenstrahlröhre

Publications (1)

Publication Number Publication Date
EP1255274A2 true EP1255274A2 (fr) 2002-11-06

Family

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Application Number Title Priority Date Filing Date
EP02100425A Withdrawn EP1255274A2 (fr) 2001-05-02 2002-04-30 Procédé de fabrication d'une cathode imprégnée pour tube à rayons cathodiques

Country Status (4)

Country Link
US (1) US20020193041A1 (fr)
EP (1) EP1255274A2 (fr)
JP (1) JP2003016931A (fr)
DE (1) DE10121445A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100433230C (zh) * 2006-07-19 2008-11-12 北京工业大学 压制型含钪扩散阴极的制备方法
RU174300U1 (ru) * 2017-06-14 2017-10-11 Демидова Елена Викторовна Торцевой металлопористый катод

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5112707A (en) * 1983-09-26 1992-05-12 Canon Kabushiki Kaisha Mask structure for lithography
US4675570A (en) * 1984-04-02 1987-06-23 Varian Associates, Inc. Tungsten-iridium impregnated cathode
NL8403031A (nl) * 1984-10-05 1986-05-01 Philips Nv Werkwijze voor het vervaardigen van een scandaatnaleveringskathode en scandaatnaleveringskathode vervaardigd volgens deze werkwijze.
US4810926A (en) * 1987-07-13 1989-03-07 Syracuse University Impregnated thermionic cathode
KR910003698B1 (en) * 1988-11-11 1991-06-08 Samsung Electronic Devices Cavity reservoir type dispenser cathode and method of the same
US5007874A (en) * 1990-10-15 1991-04-16 The United States Of America As Represented By The Secretary Of The Army Method of making a cathode from tungsten and iridium powders using a reaction product from reacting a group III A metal with barium peroxide as an impregnant
DE4114856A1 (de) * 1991-05-07 1992-11-12 Licentia Gmbh Vorratskathode und verfahren zu deren herstellung
US5114742A (en) * 1991-07-17 1992-05-19 The United States Of America As Represented By The Secretary Of The Army Preparing a scandate cathode by impregnating a porous tungsten billet with Ba3 Al2 O6, coating the top surface with a mixture of Sc6 WO12, Sc2 (WO4)3, and W in a 1:3:2 mole ratio, and heating in a vacuum
DE69204956T2 (de) * 1991-09-18 1996-05-02 Nippon Electric Co Impregnierte Kathode und Verfahren zu ihrer Herstellung.
JP2985467B2 (ja) * 1992-01-22 1999-11-29 三菱電機株式会社 含浸型カソードの製造方法
GB2279495A (en) * 1993-06-22 1995-01-04 Thorn Microwave Devices Limite Thermionic cathode
US5407633A (en) * 1994-03-15 1995-04-18 U.S. Philips Corporation Method of manufacturing a dispenser cathode
JPH11339633A (ja) * 1997-11-04 1999-12-10 Sony Corp 含浸型陰極およびその製造方法、並びに電子銃および電子管

Also Published As

Publication number Publication date
JP2003016931A (ja) 2003-01-17
DE10121445A1 (de) 2002-11-07
US20020193041A1 (en) 2002-12-19

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Inventor name: GOODHAND, CHRIS,C/O PHILIPS CORP.INTELL.PROP.

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