US2520760A - Method of producing cathodes for electronic tubes - Google Patents

Method of producing cathodes for electronic tubes Download PDF

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Publication number
US2520760A
US2520760A US740418A US74041847A US2520760A US 2520760 A US2520760 A US 2520760A US 740418 A US740418 A US 740418A US 74041847 A US74041847 A US 74041847A US 2520760 A US2520760 A US 2520760A
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US
United States
Prior art keywords
filament
pellet
cathode
cathodes
powder
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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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US740418A
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English (en)
Inventor
Gallet George
Thien-Chi Nguyen
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
CSF Compagnie Generale de Telegraphie sans Fil 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
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Application filed by CSF Compagnie Generale de Telegraphie sans Fil SA filed Critical CSF Compagnie Generale de Telegraphie sans Fil SA
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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
    • 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
    • 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.]

Definitions

  • an oxide cathode comprises a nickel tube the operative surface of which is covered with alkaline-earth oxides and within which there is located, without being in contact therewith, an insulated filament which, when brought to a red heat, heats the cathode by radiation. It is advantageous to reduce the power thus consumed to a minimum, by using it in the most efiicient manner.
  • the method essentially comprises giving to the cathode the shape of a pellet ofcompressed powder in which is embedded a heating filament covered with an insulating layer which is 'sufiiciently strong and adherent to withstand, without damage, on the one hand, the action of pressure applied during the moulding operation and, on the other hand, the effects of temperature firstly during the baking operation and subsequently during the normal operation of the valve; this notwithstandingthe difference in the ratio of expansion as between the metal of the filament and that of the pellet.
  • a first layer of powder on which the filament is arranged is first compressed lightly; a second dose of powder is then added, and the final pressure is applied.
  • a very simple means for centering the filament consists in moistening it with pure'alcohol, for example,*and sticking it in the correct position on the head of the punch: said punch is then gently inserted until it comes into contact with the first layer of powder on which it deposits the filament which is thus automatically centered in the matrix.
  • the filament be equidistant from both faces of the pellet, it is, of course, necessary to proportion suitably the weights of the two layers of powder, according to the nature and the physical characteristics of said powder, and to adjust the preliminary and final pressures according to the size of the filament and the properties of the powder, in particular its fineness.
  • the compressed pellet is subjected to baking either in an atmosphere of hydrogen or in a vacuum. It remains quite fiat if it has been moulded under a sufficient pressure and if the baking is correctly effected. Moreover, any deformation of the pellet is prevented by holding it between two plates pressed together by screws.
  • Cathodes manufactured in accordance with the method of this invention may be called by the trade name monobloc cathodes; they have numerous advantages, especially that of enabling the heating power to be used with maximum efi'iciency, since there is intimate contact between the filament and the metal of the oathode yet ensuring absolute uniformity of temperature over the entire cathode surface.
  • the cathode When the cathode is in operation, it exhibits an absolutely uniform red colour, which is an indication that there is no local overheating adjacent the filament, despite the close proximity of the latter.
  • Insulation is obtained by the use of substances which have an exceptionally high resistance at high temperature, such as, periclase, magnesite, and so forth, and which are deposited on the filament by cataphoresis under precise conditions of potential difierence, current intensity, concentration and fineness of grain.
  • a very strong and very adherent coating is obtained by means of a special fritting operation conducted in a suitable atmosphere.
  • the cathode is formed by two twin half-pellets, enclosing the filament between them, said filament being lodged in a groove provided in each half-pellet.
  • Figure 2 shows a plan view and Figure 2a a section of a half-pellet P with its groove E containing the filament F, th two ends of which protrude and are ready to be welded to the current input leads without'having to be stripped beforehand as in the previous case.
  • the groove is produced by means of a former embossed on the end of the punch.
  • a series of half-pellets of the same weight are thus manufactured and it is then only necessary to assemble them in pairs.
  • all that is required, in many cases, amongst which is the use of nickel, is to press the two halfpellets one against the other in a small press and to subject the whole assembly to baking.
  • The; assembly of the two parts is brought about by the combined effects of the temperature and the pressure.
  • the monobloc process may advantageously be applied to metals which are hard to work mechanically'as, for example, thoriated tungsten: the method of the invention makes it possible to eliminate the very delicate operations of hammering, wiredrawing and rolling the metal.
  • the said metals When the monobloc cathode contains certain metals, such as Mg, Ba, and the like, the said metals vaporize in a vacuum and condense on. the cold portions of the bulb in the form of a brilliant anduniform deposit. This. method Of manufacture can be used in making photo-electric cells, or again the said metals can act as getters.
  • the method according to the invention enables emitting cathodes, or emitting anodes in the, case of emissions of ions, of very varied natures to be obtained readily, since it is unnecessary to pass through a phase of the complete metallurgy relative, thereto, as is the case with nickel cathodes such as are used in thepresent-day technique.
  • Methodof manufacturing indireetly heated emitting cathodescontaining a heating filament embedded in a coated pellet of metallic powder comprises applying to a heating filament'an' appropriate thin insulating coating layer, inserting thecoated filament in a groove of suitable shape and dimensions provided in the inner surface of a half pellet of metallic powder, ap plying another half, pellet of the same shape, made 'of-"the same powder, by its inner surface, to the first half pellet to form a rigid block, and applying to said pellet on its outer surface a layer of thermo-emissive substance.
  • Indirectly heated emitting cathode comp1' is ing a heating filament, a thin insulating coating directly applied on the filament, a body of sintered metallic powder forming a rigid block in intiinatefcontact with the said insulated filament which is embedded therein, and a layer of thermo-emissive substance directly deposited on the surface of the said body.
  • Indirectly heated emitting cathode comprising a heating filament, a thin insulating coating directly applied on the filament, a body made of sintered metallic powder and forming a rigid block in intimate contact with the said insulated filament which is embedded therein, the thickness of said coating being substantiall less than the thickness of said body, and a thermo-emissive layer directly deposited on the surface of said body.
  • Indirectly heated emitting cathode comprising a heating filament, a thin insulating coating directly applied on the filament, a, body of sin; tered metallic powder forming a rigid block, shaped, in the form ofia pellet, in intimate contact with the saidinsulated filament which is embedded therein, andthermo-emissive layer direct,-v ly deposited on the surface of, said pellet.
  • Indirectly heated emitting cathode comprise ing a heating filament, a thin insulating coating directly applied on the filament, a body of, sintered, metallic powder, forming a rigid block in intimate contact with thesaid insulated filament which is embedded therein, the, thickness of said coating being substantially less than the thickness of said body, the said block being shaped in the form of a racket, in the, handle ofwhich are. n i cdcied. he ads. f, the filament. and, he mqm sive a r. ir ctl dspp ted on. h e. of. t e. aid make;-

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Powder Metallurgy (AREA)
  • Discharge Lamp (AREA)
US740418A 1946-03-05 1947-04-09 Method of producing cathodes for electronic tubes Expired - Lifetime US2520760A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR836527X 1946-03-05

Publications (1)

Publication Number Publication Date
US2520760A true US2520760A (en) 1950-08-29

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ID=9298138

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US740418A Expired - Lifetime US2520760A (en) 1946-03-05 1947-04-09 Method of producing cathodes for electronic tubes

Country Status (6)

Country Link
US (1) US2520760A (enrdf_load_stackoverflow)
CH (1) CH266493A (enrdf_load_stackoverflow)
DE (1) DE836527C (enrdf_load_stackoverflow)
FR (1) FR926598A (enrdf_load_stackoverflow)
GB (1) GB630624A (enrdf_load_stackoverflow)
NL (1) NL69250C (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2913812A (en) * 1954-06-16 1959-11-24 Csf Manufacture of sintered cathodes
DE1133041B (de) * 1954-10-22 1962-07-12 Gen Electric Verfahren zur Herstellung eines aus einer duennen Folie bestehenden Heizers oder Kathodenkoerpers fuer eine mit Hochfrequenz geheizte Roehre und der nach dem Verfahren hergestellte Heizer oder Kathodenkoerper
US3097419A (en) * 1960-03-11 1963-07-16 dickson
US3816079A (en) * 1971-12-29 1974-06-11 Bbc Brown Boveri & Cie Method of producing grid electrodes for electronic discharge vessels

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8611967D0 (en) * 1986-05-16 1986-10-29 English Electric Valve Co Ltd Directly heated cathodes
DE4026301A1 (de) * 1990-08-20 1992-02-27 Siemens Ag Elektronenemitter einer roentgenroehre

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1961122A (en) * 1928-08-22 1934-05-29 Westinghouse Electric & Mfg Co Thermionic cathode
US2075910A (en) * 1926-07-07 1937-04-06 Ass Elect Ind Thermionic cathode
US2106855A (en) * 1924-02-20 1938-02-01 Westinghouse Electric & Mfg Co Space-current device
US2214902A (en) * 1938-12-02 1940-09-17 Lorenz C Ag Method of producing cathode materials
US2263169A (en) * 1940-10-12 1941-11-18 Westinghouse Electric & Mfg Co Indirectly heated cathode

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2106855A (en) * 1924-02-20 1938-02-01 Westinghouse Electric & Mfg Co Space-current device
US2075910A (en) * 1926-07-07 1937-04-06 Ass Elect Ind Thermionic cathode
US1961122A (en) * 1928-08-22 1934-05-29 Westinghouse Electric & Mfg Co Thermionic cathode
US2214902A (en) * 1938-12-02 1940-09-17 Lorenz C Ag Method of producing cathode materials
US2263169A (en) * 1940-10-12 1941-11-18 Westinghouse Electric & Mfg Co Indirectly heated cathode

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2913812A (en) * 1954-06-16 1959-11-24 Csf Manufacture of sintered cathodes
DE1133041B (de) * 1954-10-22 1962-07-12 Gen Electric Verfahren zur Herstellung eines aus einer duennen Folie bestehenden Heizers oder Kathodenkoerpers fuer eine mit Hochfrequenz geheizte Roehre und der nach dem Verfahren hergestellte Heizer oder Kathodenkoerper
US3097419A (en) * 1960-03-11 1963-07-16 dickson
US3816079A (en) * 1971-12-29 1974-06-11 Bbc Brown Boveri & Cie Method of producing grid electrodes for electronic discharge vessels

Also Published As

Publication number Publication date
GB630624A (en) 1949-10-18
NL69250C (enrdf_load_stackoverflow)
DE836527C (de) 1952-04-15
FR926598A (fr) 1947-10-06
CH266493A (fr) 1950-01-31

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