US3742282A - Electrodes - Google Patents

Electrodes Download PDF

Info

Publication number
US3742282A
US3742282A US00168748A US3742282DA US3742282A US 3742282 A US3742282 A US 3742282A US 00168748 A US00168748 A US 00168748A US 3742282D A US3742282D A US 3742282DA US 3742282 A US3742282 A US 3742282A
Authority
US
United States
Prior art keywords
electrode
electrodes
electrode according
base material
covering layer
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
Application number
US00168748A
Other languages
English (en)
Inventor
G Siegle
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Application granted granted Critical
Publication of US3742282A publication Critical patent/US3742282A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/39—Selection of materials for electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/02—Details
    • H01J17/04—Electrodes; Screens

Definitions

  • the effective brightness of the apparatus is decreased and/or the resulting build-up of gas in the coating, the pressure and the composition of the filling gas and therewith the electrical values of the gap distance are altered.
  • the wall coating is electrically conductive and if it has a higher dielectric constant than the actual wall material itself, there results because of the small distances between the electrode and the wall, a disturbance of the electrical field between the electrodes sufficient so that the firing voltage or ignition tension of the spark gap is lowered.
  • electrodes of this type have been manufactured of metals, which metal electrodes, however, for all of the usual applications thereof do not have satisfactory properties.
  • this type of electrode undergoes atomization in operation and/or react with the filling gases, withdrawing noble gases and hydrogen from the container so that they cannot always be satisfactorily used.
  • These electrodes also have the disadvantage that on storage in air, as a rule, they immediately start to cover over with an oxide skin, membrane or film which on installation of the electrode, must be removed prior to use.
  • electrodes are prepared of a core material which is composed of a difficultly meltable material and which is enclosed in a jacketing or covering formed of a compound such as tantalum carbide or nitride which undergoes melting only at very high temperatures and which above all, at the thermal light emitting temperatures which amount to more than 2000C only undergoes a slight degree of evaporation which property would not be the case if the core material were not protected.
  • Still another object of the invention is to provide such electrodes which on the eventual taking up or emission of gases from the discharge space undergo no alteration in their electron discharge.
  • the mechanical strength is relatively unimportant and the operating temperature of the completed electrode lies under 500C.
  • the most suitable electrode material is one which contains the least possible amount of impurities. These impurities are particularly troublesome in that they sputter more readily or are vaporized more readily at the temperature of the spark starting points than the nitrides present in the electrode or they react chemically with the gases used in the discharger.
  • Pencil-shaped electrodes having a diameter of 1,5 mm which in accordance with the invention are prepared from ZrN of a 99.5 percent purity were manufactured so that their oxygen content after their completion remained under 3 weight percent. With a spacing of the electrode points of about 5 mm and operating in a nitrogen atmosphere, only in some cases there was deposited on the glass wall spaced 1.5 mm away following in excess of 10" sparks (individual energy mJ, spark ignition voltage 15 kV), a thin whitish to blueish transparent coating, the ignition potential, however, remaining constant.
  • the electrodes are not of the desired degree of purity, for instance, if the oxide or oxynitride content is too high, the deposit formed under the same experimental conditions will appear opaque, white and thick. The ignition voltage then as a result thereof falls off to 40 percent from the starting value.
  • An essential advantage of the use of pure nitride as electrode materials is that on storage in dry air without any protective covering, only a just perceptible difference in the working function of the electrons is observed than in the underlying nitrides. Thereby there is avoided the necessity for special handling of the electrodes, as the required electrical stability properties are not interfered with even after installation of the electrodes.
  • the electrode material in accordance with the invention can advantageously be used as electrodes in spark gap and other discharge installations such as incadescent, glow, and flash lamps as well as in pre-spark gap and ignition installations for combustion motors.
  • the base materials no strong restrictions are made. These materials should withstand the mechanical and thermal treatment during fabrication of the electrodes, they should be able to be operative to endure the mechanical and thermal stresses during operation, and they should be sufficiently dense to avoid degassing when inserted into the gas filled spark gas container. in cases where the electrode material is plasma sprayed or soldered or welded onto the base material, it should have roughly the same thermal expansion coefficient.
  • Base materials and alloys like Fe, Mo, Ta, W, Ni (Fe- Ni-Cr-and Fe-Ni-alloys like Kovar, Vacon, Vacovit), and steel are thus most favourable.
  • Kovar or Vacon are well suited for plasma-sprayed ZrN-coatings.
  • the base-material of the electrode is made from a wiretack out of a Fe-Ni-Cr-alloy (Kovar) with a diameter of 1 mm and a length of 30 mm. Only one end of the wire-tack has to be covered with the actual electrode materials. To enlarge the adhesion of that material on the base, the said end is sandblasted up to 3 mm from the end of the wire-tack, using grains of sand of about 0.2-0.5 mm diameter. After which the wire-tack is cleaned in running water and degassed in a wet H,-or H,-N,-stream at 850C for 15 min. The basematerial is now prepared to be covered with the sputtering and vaporisation resistant material.
  • Kovar Fe-Ni-Cr-alloy
  • This coating below the tip is necessary, otherwise the spark may start not on the coating, but on the base material which has a much higher sputtering yield than the coating.
  • the spraying, time necessary is about s. After spraying both the electrode and the holder are covered with a layer of the sprayed material and the electrode has to be broken out of this coherent layer, which can easily be done.
  • intense cooling is necessary by a gas stream from a nozzle using N or inert Ar. This does not reduce adhesion of the coating if the droplets of the powder reach the electrode in a molten state.
  • the gases which flow through the burner should likewise be Ar and or N
  • the spraying is done most favorably in a chamber with a N,-or Ar-atmosphere so as to avoid oxidation of the sprayed materials. But spraying in air is possible too.
  • the unavoidable oxide content is reduced by heating the electrode using a radiant heater after spraying in an appropriate atmosphere N, of high pressure for nitrides like ZrN.
  • ZrN-coatings are heated to about 750C and more in N, of a pressure of at least 1 bar for about 1 min to reduce the O-content by a factor of 2 to less than 3 weight percent.
  • Electrode adapted for use in gas filled spark gap and discharge containers comprising a material resistant to sputtering and vaporization consisting of at least one nitride of a metal selected from the group consisting of Hf, Zr and Ta, said metal nitride having an 0, content bound as an oxide or oxynitride of less than about 5 weight percent and a content of other impurities of less than about 1.5 weight percent.
  • Electrode according to claim 2 having an electrode base material selected from the group consisting of W, Mo, Ta, Ni, Fe-Ni-Cr-alloy, Fe -Ni alloy and steel and contains in part a covering layer of the same materials which form the actual electrode material for the sparks.
  • Electrode according to claim 2 wherein said covering layer has a thickness of about 0.i-l mm.
  • Electrode according to claim 2 wherein said metallic base material is at least in part provided with a covering layer of said materials by plasma-spraying and has an oxygen content of less than 5 weight percent.

Landscapes

  • Spark Plugs (AREA)
  • Gas-Filled Discharge Tubes (AREA)
US00168748A 1970-08-04 1971-08-03 Electrodes Expired - Lifetime US3742282A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2038645A DE2038645C3 (de) 1970-08-04 1970-08-04 Verwendung von Hafnium-, Zirkonium- und oder Tantalnitrid als Werkstoff für Elektroden

Publications (1)

Publication Number Publication Date
US3742282A true US3742282A (en) 1973-06-26

Family

ID=5778815

Family Applications (1)

Application Number Title Priority Date Filing Date
US00168748A Expired - Lifetime US3742282A (en) 1970-08-04 1971-08-03 Electrodes

Country Status (6)

Country Link
US (1) US3742282A (enExample)
BR (1) BR7104982D0 (enExample)
DE (1) DE2038645C3 (enExample)
FR (1) FR2103959A5 (enExample)
GB (1) GB1306887A (enExample)
SE (1) SE380930B (enExample)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3959683A (en) * 1974-10-10 1976-05-25 Panel Technology, Inc. Gas discharge display panel device sputter resistant segmented electrodes
US4044276A (en) * 1976-04-09 1977-08-23 Gte Sylvania Incorporated High pressure mercury vapor discharge lamp having improved electrodes
US4136227A (en) * 1976-11-30 1979-01-23 Mitsubishi Denki Kabushiki Kaisha Electrode of discharge lamp
US4297613A (en) * 1979-05-08 1981-10-27 International Business Machines Corporation D.C. Scan panel
US4890035A (en) * 1986-11-18 1989-12-26 Eltro Gmbh Discharge electrode with microstructure surface

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3959683A (en) * 1974-10-10 1976-05-25 Panel Technology, Inc. Gas discharge display panel device sputter resistant segmented electrodes
US4044276A (en) * 1976-04-09 1977-08-23 Gte Sylvania Incorporated High pressure mercury vapor discharge lamp having improved electrodes
US4136227A (en) * 1976-11-30 1979-01-23 Mitsubishi Denki Kabushiki Kaisha Electrode of discharge lamp
US4297613A (en) * 1979-05-08 1981-10-27 International Business Machines Corporation D.C. Scan panel
US4890035A (en) * 1986-11-18 1989-12-26 Eltro Gmbh Discharge electrode with microstructure surface

Also Published As

Publication number Publication date
GB1306887A (en) 1973-02-14
FR2103959A5 (enExample) 1972-04-14
DE2038645C3 (de) 1974-03-21
DE2038645B2 (de) 1973-08-23
BR7104982D0 (pt) 1973-04-12
DE2038645A1 (de) 1972-02-24
SE380930B (sv) 1975-11-17

Similar Documents

Publication Publication Date Title
US3503787A (en) Method of making refractory aluminum nitride coatings
US3625848A (en) Arc deposition process and apparatus
US4723589A (en) Method for making vacuum interrupter contacts by spray deposition
JP3566974B2 (ja) 高圧放電ランプ
DE3016807A1 (de) Verfahren zur herstellung von silizium
US20080176479A1 (en) Conductive element and method of making
US3798492A (en) Emissive electrode
US2697183A (en) High-pressure electric discharge lamp
US3742282A (en) Electrodes
EP1149444A1 (en) Gas discharge tube
US3630872A (en) Process for the manufacture of an electrical contact point
US3159461A (en) Thermionic cathode
US3742280A (en) Pre ignition gap for combustion engine ignition systems
US2831784A (en) Gastinger
US2677623A (en) Process for manufacturing electron emissive material and electrodes
JP2004143591A (ja) 窒化アルミニウム（ＡｌＮ）基板の製造方法
US1566848A (en) Incandescent lamp
GB1115055A (en) Film deposition in an evacuated chamber
US1832009A (en) Vapor discharge device
JPS6439728A (en) Manufacture of semiconductor by plasma reaction
US2899299A (en) Method of manufacturing sintered
US3237043A (en) Gas-filled electric incandescent lamp
US2488727A (en) Electrode for electric discharge devices
US1803175A (en) Electric-arc device
JPS643350B2 (enExample)