US3611523A - Electric discharge tube having at least one non-emitting electrode which consists at least superficially of nickel - Google Patents

Electric discharge tube having at least one non-emitting electrode which consists at least superficially of nickel Download PDF

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Publication number
US3611523A
US3611523A US826599A US3611523DA US3611523A US 3611523 A US3611523 A US 3611523A US 826599 A US826599 A US 826599A US 3611523D A US3611523D A US 3611523DA US 3611523 A US3611523 A US 3611523A
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United States
Prior art keywords
gold
nickel
layer
anode
electric discharge
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Expired - Lifetime
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US826599A
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English (en)
Inventor
Ernst Sigmund Den Dulk
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US Philips Corp
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US Philips Corp
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J19/00Details of vacuum tubes of the types covered by group H01J21/00
    • H01J19/28Non-electron-emitting electrodes; Screens
    • H01J19/30Non-electron-emitting electrodes; Screens characterised by the material
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00Discharge tubes and lamps
    • H01J2893/0001Electrodes and electrode systems suitable for discharge tubes or lamps
    • H01J2893/0012Constructional arrangements
    • H01J2893/0019Chemical composition and manufacture

Definitions

  • the invention relates to an electric discharge tube having at least one non-emitting electrode which 'consists at least superficially of nickel.
  • the invention relates particularly to a rectifier tube for high voltages which is provided with an anode consisting of nickel-plated iron.
  • a cathode therefore usually consists of a nickel support for the emitter layer.
  • Cold electrodes for example, screens and anodes
  • these materials are not only cheap but can also be readily machined. This is of particular importance for anodes for very high voltages, since in this case the edges have to be beaded to avoid sputtering phenomena. Materials such as molybdenum present great difficulties upon beading due to their hardness.
  • a drawback of the use of materials which consist superficially of nickel, for example, nickel-plated iron, however, is that, if during the manufacture or during operation, emitting material of the cathode is deposited on said material, the cold electrode starts emitting which may give rise to breakdown of the tube which has for its result that the cathode melts and short-circuit occurs which may have expensive consequences in particular operated with high voltages.
  • the conventional degassing temperature lies at approximately 820 to 850 C. At such a high temperature the layer of gold fully disappears in the nickel layer and it is found that the emission-suppressing effect of the layer of gold is lost.
  • a metal for example, molybdenum
  • the gold does not dissolve, it is true, but the danger exists that if the electrode, during operation, obtains a high temperature, gold evaporates and the cathode is poisoned.
  • FIG. 1 is a longitudinal cross-sectional view through the rectifier tube for high voltages provided with an anode according to the invention
  • FIG. 2 shows a part A of the anode wall prior to degassing of the tube.
  • Reference numeral 1 in the figure is a glass envelope, 2 denotes the supply pins for the filament and cathode 3.
  • the anode 4 consists of nickel-plated iron 6, a layer of gold 8 being provided on the layer of nickel 7 (FIG. 2).
  • the gold 8 is dissolved in the nickel 7 by degassing at 780 C. for to seconds.
  • the nickel layer 7 has a thickness of 16 while the original gold layer 8 was thinner than l
  • the gold layer 8 therefore disappears entirely in the nickel layer. Nevertheless the emission-suppressing effect of the gold is found to be maintained entirely if degassing has taken place at a temperature of maximally 800 C.
  • the anode 4 is secured in the wall 1 of the tube by means of a tubular current supply member 5 consisting of an oxidized chromium-iron alloy.
  • the supply conductor 5 may previously be secured to the anode 4.
  • a large number of anodes are coated in a drum in known manner with a layer of gold, the thickness of which is smaller than I by means of a bath which contains potassium-gold cyanide and ammonia, which is obtained commercially under the registered trade name Atomex. It has been found that the oxidized surface of the supply conductor 5 is not covered with gold so that cleaning thereof is not necessary.
  • the temperature at which the gold is dissolved in the nickel is found to be critical above 800 C. From socalled short-circuit experiments, in which a rectifier for 25 to 30 kv. and provided with a diode test tube is shortcircuited until the anode of the test tube has reached a temperature of 600 C. after which the short circuit is removed, it was found that in the case of anodes consisting of nickel-plated iron not treated with gold the anode emission is so strong that the cathode melts. Reject percentage 100. In a large number of gold-plated anodes, the following results were obtained dependent upon the tem perature at which the gold was dissolved in the anode nickel layer; gold dissolved at 780 C.; 800 C.; 815 C.; 850 C. Rejects in short circuit test: 0%; 30%; 100%.
  • 800 C. hence is the maximally permissible degassing temperature. It has been found that upon degassing at 780 C. the conventional duration of 100 to 110 seconds can be maintained which time is often used upon degassing at 825 C' For applying the invention, the cycle time of the mill constructed for a pump temperature of 825 C. need consequently not be varied.
  • the invention may also be applied in other cases in which undesired emission of electrodes not destined for electron emission, or other nickel surfaces has to be suppressed. for example, in the concentration plates in electron beam pentodes, in anodes for X-ray tubes, and the like.
  • a method of manufacturing an electric discharge tube comprising coating at least one non-emitting electrode with a layer of nickel, coating the nickel layer of said non-emitting electrode with a layer of gold, assembling emitting and non-emitting electrodes within said electric discharge tube and evacuating and degassing said electric discharge tube, said evacuating and degassing comprising heating said non-emitting electrode at a temperature at which occluded gases are released from said electrode and not greater than 800 C. to fully dissolve the gold in said nickel layer, thereby maintaining the emission-suppressing effect of said non-emitting electrode.
  • a method of'manufacturing an electric discharge tube as claimed in claim 1 wherein coating the nickel layer comprises this step of coating thereon a layer of gold having a thickness not greater than 1p. and heating said non-emitting electrode to dissolve the gold in said nickel layer comprises heating to a temperature of 780 C. for a time interval between and seconds.
  • a method of manufacturing an electric discharge tube as claimed in claim 1 wherein coating at least one non-emitting electrode comprises coating with a layer of nickel having a thickness at least ten times greater than the thickness of the layer of gold.
  • a method of manufacturing an electric discharge tube as claimed in claim 1 wherein coating the nickel layer comprises gold-plating in a bath essentially consisting of potassium-gold-cyanide and ammonia.

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  • Electroplating Methods And Accessories (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Lasers (AREA)
US826599A 1968-05-31 1969-05-21 Electric discharge tube having at least one non-emitting electrode which consists at least superficially of nickel Expired - Lifetime US3611523A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6807777A NL6807777A (pl) 1968-05-31 1968-05-31

Publications (1)

Publication Number Publication Date
US3611523A true US3611523A (en) 1971-10-12

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ID=19803805

Family Applications (1)

Application Number Title Priority Date Filing Date
US826599A Expired - Lifetime US3611523A (en) 1968-05-31 1969-05-21 Electric discharge tube having at least one non-emitting electrode which consists at least superficially of nickel

Country Status (11)

Country Link
US (1) US3611523A (pl)
AT (1) AT287860B (pl)
BE (1) BE733810A (pl)
CH (1) CH487496A (pl)
DE (1) DE1924004A1 (pl)
ES (1) ES367842A1 (pl)
FR (1) FR2009749A1 (pl)
GB (1) GB1224869A (pl)
NL (1) NL6807777A (pl)
PL (1) PL71409B1 (pl)
ZA (1) ZA693594B (pl)

Also Published As

Publication number Publication date
FR2009749A1 (pl) 1970-02-06
BE733810A (pl) 1969-12-01
PL71409B1 (pl) 1974-06-29
ES367842A1 (es) 1971-06-16
DE1924004A1 (de) 1969-12-04
GB1224869A (en) 1971-03-10
ZA693594B (en) 1971-01-27
AT287860B (de) 1971-02-10
NL6807777A (pl) 1969-12-02
CH487496A (de) 1970-03-15

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