US3056061A - Method of manufacturing nickel supports for oxide cathodes and cathodes provided with such supports - Google Patents

Method of manufacturing nickel supports for oxide cathodes and cathodes provided with such supports Download PDF

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Publication number
US3056061A
US3056061A US3183A US318360A US3056061A US 3056061 A US3056061 A US 3056061A US 3183 A US3183 A US 3183A US 318360 A US318360 A US 318360A US 3056061 A US3056061 A US 3056061A
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United States
Prior art keywords
oxide
supports
magnesium
nickel
support
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Expired - Lifetime
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US3183A
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English (en)
Inventor
Melsert Hans
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00Details 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
    • H01J1/02Main electrodes
    • H01J1/13Solid thermionic cathodes
    • H01J1/20Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H01J1/26Supports for the emissive material
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00Apparatus 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
    • H01J9/02Manufacture of electrodes or electrode systems
    • H01J9/04Manufacture of electrodes or electrode systems of thermionic cathodes

Definitions

  • the active nickel commonly used for oxide cathodes contains some impurities, inter alia magnesium, manganese, silicon, and iron, from which especially magnesium is favourable for the emission of electrons due to reduction of barium oxide.
  • magnesium has the disadvantage that it continuously evaporates from the cathode during opa mirror gives rise to a capacitance between the electrodes which becomes greater and greater. More particularly the resulting varying capacitance between the anode and the control grid is very troublesome for the performance of the device of which the tube forms part.
  • This disadvantage may be avoided by the use of nickel of high purity, wherein the impurities are present in less than 0.022% by weight.
  • nickel brings about .a lower emission of electrons due to the reduction
  • the present invention permits of avoiding the troublesome evaporation of magnesium from the cathode support without the electron emission being detrimentally affected.
  • tubular support for an oxide cathode which support consists of nickel containing inter alia magnesium as an im purity
  • steps are taken to ensure that, during heating to from 1000 C. to 1200 C., oxygen can diffuse into the nickel from the surface opposite to the surface intended as the support for the emissive layer, until at least the magnesium present in the nickel has been bound for the greater part, but not completely, by oxygen. magnesium remains free in the than half the wall thickness.
  • the tube means may communicate with the oxygen contained in the surrounding air, or, in the alternative, for a more positive supply of oxygen for the dilfusion process the tube means may be connected to a gas circulating and/ or feeding system that pumps oxygen to the tube means and tubular support. It has been found that, if the support has a wall thickness of 0.1 mm., heating at 1100 C., for a period of 20 minutes yields the desired result.
  • the outer surface of the tube is kept in a neutral atmosphere such as nitrogen, for example, by furnishing the interior of the oven chamher with a nitrogen atmosphere.
  • the surface on which the electron-emissive material will be provided later on is then still active since it still contains free magnesium, but it has been found that in the part of the support-wall in which oxygen has penetrated, the magnesium is comis still present in the remaining part of the support-wall does not evaporate either.
  • the said surface of the support with a wall thickness of 0.1 mm. may alternatively be covered with an oxide layer, for example a 0.1 mm. layer of nickel-oxide, from which oxygen can be freed for heating at 1100" C. during 10 min. and diffuse into the nickel in a neutral vacuo.
  • an oxide layer for example a 0.1 mm. layer of nickel-oxide, from which oxygen can be freed for heating at 1100" C. during 10 min. and diffuse into the nickel in a neutral vacuo.
  • the said surface is insulated with respect to the heater of the cathode and that the heating process can coincide with the heating carried out for activating the electron-emissive layer after the cathode has been mounted in a discharge tube.
  • the temperature necessary for activating and disintegrating the emissive layer ordinarily consisting of equal parts barium oxide and strontium oxide, also lies between 1000 C., and 1200 C. In any case, the process of heating to the said temperature must not be continued until the Mg has been bound throughout
  • the content of impurities is low.
  • the Mg-content of the said nickel is, for example, from 0.05 to 0.06% by weight.
  • the nickel further may contain 0.01% silicon; 0.02% iron and 0.101% manganese.
  • impurities with a percentage of weight lower than 0.02% do not not react notably with the emitting oxides.
  • Nickel containing such small percentages of impurities is therefore also said to be passive. From the said impurities only magnesium, and to a lesser degree also manganese, can give trouble due to evaporation.
  • a tubular sleeve 1 consisting of active nickel as mentioned above and having a wall thickness of 0.1 mm.
  • an oxide coating 2 consisting of equal parts barium carbonate and strontium carbonate.
  • the inner surface of the sleeve has been covered with nickel oxide 3.
  • the sleeve 1 is heated at 1100 C. for 10 min. whereby the carbonates are converted into oxides and oxygen from the NiO layer 3 difluses into the nickel of the sleeve 1, to about half its thickness, thereby completely converting the Mg and, possibly the other impurities, into oxides, so that part 5 of the sleeve becomes passive.
  • the remaining part 4 remains active. It is desirable that the part 5 extends at least over half the wall thickness.
  • a method of manufacturing an oxide-coated cathode comprising the steps of providing a nickel support containing magnesium as an impurity, said support havsecond surface and leave free the remaining portion of said magnesium adjacent to said first surface.
  • a method of manufacturing an oxide-coated cathode comprising the steps of providing a nickel support containing magnesium as an impurity, said support havpredetermined part of said distance to cause a substansaid magnesium to become bound with said oxygen adjacent to said second surface and leave free the remaining portion of said magnesium adjacent to said first surface.
  • said nickel support comprises a tubular member having a lateral wall, said first and second surfaces comprising the interior an exterior surfaces, respectively, of said wall, and during said heating step said oxygen passes through the interior of said tubular member for said diffusion thereof and said first surface is maintained in a neutral .atmosphere.
  • a method according to claim 2 further comprising the step of covering said second surface with an oxide layer prior to said heating of said support to provide said oxygen for said diffusion.
  • a nickel support containing magnesium as an impurity for supporting an electron emissive layer of an oxide-coated cathode comprising a first surface for support of an alkaline earth oxide, and a second lateral surface disposed a predetermined distance from said first surface, a substantial portion of the magnesium being bound adjacent to said second surface and the remaining portion thereof free adjacent to said first surface.
  • a nickel support containing magnesium as an impurity for supporting an electron emissive layer of an oxide-coated cathode comprising a hollow cylinder with a lateral wall having a predetermined thickness, said lateral wall having a first surface to support said emissive layer, and a second surface, a substantial portion of the magnesium being bound adjacent to said second surface and the remaining portion thereof being free adjacent to said first surface.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid Thermionic Cathode (AREA)
US3183A 1959-03-06 1960-01-18 Method of manufacturing nickel supports for oxide cathodes and cathodes provided with such supports Expired - Lifetime US3056061A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL236877 1959-03-06

Publications (1)

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US3056061A true US3056061A (en) 1962-09-25

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US3183A Expired - Lifetime US3056061A (en) 1959-03-06 1960-01-18 Method of manufacturing nickel supports for oxide cathodes and cathodes provided with such supports

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US (1) US3056061A (fr)
DE (1) DE1105071B (fr)
FR (1) FR1256158A (fr)
GB (1) GB947999A (fr)
NL (1) NL101694C (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3113236A (en) * 1959-06-23 1963-12-03 Philips Corp Oxide dispenser type cathode
US3262814A (en) * 1960-12-15 1966-07-26 Philips Corp Method for coating an indirectly heated cathode
US3432900A (en) * 1964-08-17 1969-03-18 Sylvania Electric Prod Method of making a pencil type indirectly heated cathode
US3495121A (en) * 1967-04-10 1970-02-10 Siemens Ag Indirectly heated dispenser cathode for electrical discharge vessels
US3911312A (en) * 1973-06-06 1975-10-07 Philips Corp Oxide cathode for an electric discharge tube
US4532452A (en) * 1983-10-31 1985-07-30 Rca Corporation Cathode structure for a cathodoluminescent display devices
US20060076871A1 (en) * 2002-11-23 2006-04-13 Koninlijke Philips Electronics N.V. Vacuum tube with oxide cathode

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1139827A (fr) * 1977-12-06 1983-01-18 George L. Davis Cathode d'oxydation et methode de preparation de la poudre metallurgique du nickel pour ladite cathode
JPH0677435B2 (ja) * 1985-03-18 1994-09-28 株式会社日立製作所 傍熱形陰極の製造方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2778970A (en) * 1952-06-07 1957-01-22 Rca Corp Core alloy for indirectly heated cathodes
US2912611A (en) * 1953-08-14 1959-11-10 Int Standard Electric Corp Thermionic cathodes

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2778970A (en) * 1952-06-07 1957-01-22 Rca Corp Core alloy for indirectly heated cathodes
US2912611A (en) * 1953-08-14 1959-11-10 Int Standard Electric Corp Thermionic cathodes

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3113236A (en) * 1959-06-23 1963-12-03 Philips Corp Oxide dispenser type cathode
US3262814A (en) * 1960-12-15 1966-07-26 Philips Corp Method for coating an indirectly heated cathode
US3432900A (en) * 1964-08-17 1969-03-18 Sylvania Electric Prod Method of making a pencil type indirectly heated cathode
US3495121A (en) * 1967-04-10 1970-02-10 Siemens Ag Indirectly heated dispenser cathode for electrical discharge vessels
US3911312A (en) * 1973-06-06 1975-10-07 Philips Corp Oxide cathode for an electric discharge tube
US4532452A (en) * 1983-10-31 1985-07-30 Rca Corporation Cathode structure for a cathodoluminescent display devices
US20060076871A1 (en) * 2002-11-23 2006-04-13 Koninlijke Philips Electronics N.V. Vacuum tube with oxide cathode

Also Published As

Publication number Publication date
GB947999A (en) 1964-01-29
FR1256158A (fr) 1961-03-17
DE1105071B (de) 1961-04-20
NL101694C (fr)

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