US1794810A - Incandescent cathode for electric discharge tubes - Google Patents

Incandescent cathode for electric discharge tubes Download PDF

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Publication number
US1794810A
US1794810A US713223A US71322324A US1794810A US 1794810 A US1794810 A US 1794810A US 713223 A US713223 A US 713223A US 71322324 A US71322324 A US 71322324A US 1794810 A US1794810 A US 1794810A
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US
United States
Prior art keywords
nitride
wire
zirconium
cathode
electric discharge
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
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US713223A
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English (en)
Inventor
Anton Eduard Van Arkel
Bruijnes Johannes
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Koninklijke Philips NV
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Philips Gloeilampenfabrieken NV
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    • 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
    • H01J1/14—Solid thermionic cathodes characterised by the material
    • 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
    • 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
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2933—Coated or with bond, impregnation or core
    • Y10T428/294—Coated or with bond, impregnation or core including metal or compound thereof [excluding glass, ceramic and asbestos]
    • Y10T428/2958—Metal or metal compound in coating

Definitions

  • This invention has reference to incandescent cathodes for electric discharge tubes such as rectifiers with or without gaseous filling; receiving or transmission tubes for wireless telegraphy, telephony or similar purposes, with three or more electrodes and with or without gaseous filling; X-ray tubes; are lamps with enclosed arc discharge; etc.
  • the invention has for its object to choose such material for incandescent cathodes that the emission of electrons can be obtained with less energy than in the case of the material usually used in practice for such electrodes, that is to say tungsten.
  • the incandescent cathode contains at its surface titanium 2Q nitride or zirconium nitride or hafnium nitride or a mixture of two or more of these compounds.
  • the said compounds yield a greater emission of electrons than tungsten which is perceptible even when these compounds constitute part of the surface of the electrode. This characteristic stands out most clearly when the surface of the electrode consists entirely of one or more of the said compounds.
  • the said compounds For the emission of electrons it is essential that the said compounds be found on the surface of the electrode but it is not necessary that the entire electrode should consist of the said compounds. On the contrary it is often preferred in practice to apply one or more of the said compounds to a body consisting of some other suitable material.
  • this body may consist of an highly refractory material which is a goo conductor of electricity, preferably a highly refactory metal such as platinpm or molybdenum or tungsten or'a metal a 0y.
  • metals or metal alloys having a coefficient of expansion corresponding to that of the compound applied for example platinum rhodium in the case of zirconium nitride.
  • the melting point of the said core material should lie above the temperature favorable to the emission of electrons, which for example in the case of zirconium nitride lies near about 1000 C., but in addition it may be required for the manufacture 'conium nitride or hafnium nitride to any body. 1 n
  • a body is heated in an atmosphere containing a reducing substance, nitrogen, and one or more dissociable compounds of titanium or Zirconium or hafnium in a state of vapor, to such a temperature that on its surface titanium nitride or zirconium nitride or hafnium nitride or a mixture of these compounds is precipitated.
  • the halogenides of these elements preferably the chlorides, may be used.
  • the reducing substance may for example consist of an alkaline vapor, but preferably it consists of carefully dried hydrogen.
  • a mixture of nitrogen and hydrogen is delivered through a glass tube 1.
  • the content 2 where it is strongly cooled. since the vessel '2 is surrounded by a vessel 3 provided-with liquid air.
  • the mixture then flows through the tube 4 to the vessel 5 in which the substance 6 is enclosed.
  • the said substance 6 is preferably zirconium chloride and the vessel 5 should be maintained at such a temperature that the chloride evaporates to a sufficient extent.
  • the tube 7 as well as the vessel 8 should be maintained at such a temperature that the zirconium chloride remains in a state of vapor.
  • the vessels 5 and 8 and the tube 7 may be heated for example to a temperature of about 150 to 300 C.
  • the vessel 8 is hermetically sealed at the top by a stopper 9, for example of glass, in which the leading-in wires 10 and 11 are sealed.
  • the wire 12 is in conductive connection with the wires 10 and 11, for example by means of small screws, so as to enable it to be heated electrically $0 a suitable temperature.
  • this temperature may be about 1800 C.
  • a coating of zirconium nitride is produced on the wire at 1000 C. though at a much lower speed than at a higher. temperature.
  • the speed of reaction is found to increase as the temperature is raised.
  • the temperature should not be increased too much otherwise the nitride coating grows on the wire so rapidly that a good coherent layer cannot be therefor obtained. In general it seems undesirable to increase the temperature over about 2000 C.
  • the choice of the material for the wire 12 depends on not only its final utilization but also on the temperature which is to be maintained for the reaction. If 1000 C. is con sidered sufiicient, nickel for example may be used. It is more advantageous to use for example tungsten or molybdenum or platinum at higher temperatures.
  • the.hydrogen of the gas mix-- collected in 14 may be used again after being purified from hydrochloric acid.
  • the reaction is continued until the precipitate on the wire 12 has obtained the desired thickness, which can be easily ascertained by measuring for example the change of resistance of the wire 12.
  • the treated wire 12 which therefore consists for example of a tungsten core with a precipitate of zirconium nitride is suitable for use as an incandescent cathode in a discharge tube.
  • the incandescent cathode thus obtainedhas very important advantages.
  • the emission of electrons is very high. At about 900-1000 C. the emission is altogether sufficient for example for receiving tubes for wireless ielegraphy although the vapor tension is still imperceptible. It is for example possible to obtain a current of electrons of about five milliampers by supplying only an energy of one watt to the incandescent wire.
  • the emission of electrons remains invar1ab e for a long time. It has for example been ascertained that after 1000 hours of service the emission was still practically the same as at. the beginning.
  • the coating of zirconium nitride adheres well to the core and does not crumble ofi.
  • zirconium nitride is a very good conductor and that the wire can be welded to nickel or to any other suitable material without any difiiculty. It is of course obvious that this is of great convenience in fixing the incandescent wire to the supporting wire.
  • titanium chloride TiCl is used as the dissociable compound, said titanium chloride boiling at 140 C., so that the vapor pressure at ordinary temperatures is high enough for the reaction to take place, and it is therefore superfluous to heat the vessels 5 and 8.
  • the wire 12 is to be heated to a temperature that may vary from 1000 to 2000.C.
  • the TiCl is partly reduced by the hydrogen into TiCl which is slightly volatile and is precipitated on the wall of the vessel '8. About the titaniumnitridethefollowingmaybestated.
  • the emission has been found to have a considerable value at a temperature of about 1600C.
  • I a Incandescent wires according to the invention' more particularly those containing zir-.
  • conium nitride may be used to advantage for example in small receiving tubes with three or more electrodes such as are used by amatours for radiotelegraphic purposes.
  • the incandescent cathode consumes only onefourth to one-fifth of the energy required by a tungsten cathode and this is of importance particularly for the amateurs.
  • the incandescent cathode according to the invention may render good services in X-ray tubes and more particularly in high vacuum X-ray tubes.
  • an incandescent cathode according to the invention' may be arranged opposite an anode of for example tungsten; the light is produced principally by the latter.
  • a cathode for electric dischar e tubes comprising a metallic core and a sur ace consistingof -a nitride of at leastone of the group of elements comprising titanium, zircon1um andhafnium.
  • a process for making a filament of the character described comprising vaporizing at least one of the chlorides of the group of In testimony whereof we afiix our signatures, at the city of Eindhoven, this 22nd day of April, 1924.
  • a cathode for electric discharge tubes characterized in that it consists o a body of at least one hi hly refractory metallic material, said body eing coated with a compound of at least one of the group of elements comprising'titanium, zlrcomum and hafnium.
  • a cathode for electric discharge tubes characterized in that it consists of a core 0 at least one highly refractory metallic material, covered with a coating that principally consists of zirconium-nitride.
  • a process for making a filament of the character hereinbefore described which includes the step of heating a wire in a,fluid comprising a volatilized compound of a metal, a reducing agent for reducing the com pound and an element for combinin with the liberated metal from the compoun 6.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid Thermionic Cathode (AREA)
  • Cold Cathode And The Manufacture (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
US713223A 1923-05-18 1924-05-14 Incandescent cathode for electric discharge tubes Expired - Lifetime US1794810A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL216160X 1923-05-18

Publications (1)

Publication Number Publication Date
US1794810A true US1794810A (en) 1931-03-03

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US713223A Expired - Lifetime US1794810A (en) 1923-05-18 1924-05-14 Incandescent cathode for electric discharge tubes

Country Status (5)

Country Link
US (1) US1794810A (enrdf_load_stackoverflow)
DE (1) DE465276C (enrdf_load_stackoverflow)
FR (1) FR581574A (enrdf_load_stackoverflow)
GB (1) GB216160A (enrdf_load_stackoverflow)
NL (1) NL16794C (enrdf_load_stackoverflow)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2671739A (en) * 1949-06-22 1954-03-09 Bell Telephone Labor Inc Plating with sulfides, selenides, and tellurides of chromium, molybdenum, and tungsten
US2704727A (en) * 1951-10-08 1955-03-22 Ohio Commw Eng Co Method of deposition of non-conductive copper coatings from vapor phase
US2717915A (en) * 1952-11-13 1955-09-13 Zalman M Shapiro Apparatus for production of purified metals
US2780553A (en) * 1955-07-07 1957-02-05 Ohio Commw Eng Co Process of providing a controlled atmosphere containing a heat decomposable metal compound
US2822302A (en) * 1956-01-16 1958-02-04 Radio Mfg Company Inc Non-emissive electrode
US2836514A (en) * 1953-11-16 1958-05-27 Metallgesellschaft Ag Hard surface coated gear member
US2864731A (en) * 1956-07-13 1958-12-16 David H Gurinsky Forming protective films on metal
US2865791A (en) * 1954-03-05 1958-12-23 Metallgesellschaft Ag Metal nitride coating process
US2926111A (en) * 1958-04-03 1960-02-23 Donald G Schweitzer Method of forming a protective coating on ferrous metal surfaces
US2960642A (en) * 1958-04-17 1960-11-15 Quartz & Silice S A Dielectric films and capacitors employing the same
US3089949A (en) * 1958-11-28 1963-05-14 Westinghouse Electric Corp Arc welding method and article

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1001239B (de) * 1953-06-23 1957-01-24 Metallgesellschaft Ag Korrosionsbestaendige Elektrode fuer Elektrofilter
DE1078095B (de) * 1953-07-13 1960-03-24 Metallgesellschaft Ag Korrosionsbestaendige Ausstroemerelektrode fuer Elektrofilter
DE1101618B (de) * 1953-10-02 1961-03-09 Int Standard Electric Corp Verfahren zur Herstellung eines Elektrolytkondensators mit einer Titananode
DE954301C (de) * 1953-11-26 1956-12-13 Metallgesellschaft Ag Feinmaschinenlager mit gehaerteter Oberflaeche
DE1041320B (de) * 1954-03-09 1958-10-16 Metallgesellschaft Ag Verfahren zum Gasplattieren mit hochschmelzenden Nitriden
DE1001873C2 (de) * 1954-03-26 1957-07-11 Metallgesellschaft Ag Behaelter und sonstige Apparateteile zur Herstellung von Metallen aus ihren Halogeniden

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2671739A (en) * 1949-06-22 1954-03-09 Bell Telephone Labor Inc Plating with sulfides, selenides, and tellurides of chromium, molybdenum, and tungsten
US2704727A (en) * 1951-10-08 1955-03-22 Ohio Commw Eng Co Method of deposition of non-conductive copper coatings from vapor phase
US2717915A (en) * 1952-11-13 1955-09-13 Zalman M Shapiro Apparatus for production of purified metals
US2836514A (en) * 1953-11-16 1958-05-27 Metallgesellschaft Ag Hard surface coated gear member
US2865791A (en) * 1954-03-05 1958-12-23 Metallgesellschaft Ag Metal nitride coating process
US2780553A (en) * 1955-07-07 1957-02-05 Ohio Commw Eng Co Process of providing a controlled atmosphere containing a heat decomposable metal compound
US2822302A (en) * 1956-01-16 1958-02-04 Radio Mfg Company Inc Non-emissive electrode
US2864731A (en) * 1956-07-13 1958-12-16 David H Gurinsky Forming protective films on metal
US2926111A (en) * 1958-04-03 1960-02-23 Donald G Schweitzer Method of forming a protective coating on ferrous metal surfaces
US2960642A (en) * 1958-04-17 1960-11-15 Quartz & Silice S A Dielectric films and capacitors employing the same
US3089949A (en) * 1958-11-28 1963-05-14 Westinghouse Electric Corp Arc welding method and article

Also Published As

Publication number Publication date
DE465276C (de) 1928-09-15
GB216160A (en) 1925-09-17
FR581574A (enrdf_load_stackoverflow) 1924-12-02
NL16794C (enrdf_load_stackoverflow)

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