GB871375A - Improvements in or relating to heating filaments for indirectly heated electrodes - Google Patents

Improvements in or relating to heating filaments for indirectly heated electrodes

Info

Publication number
GB871375A
GB871375A GB2278057A GB2278057A GB871375A GB 871375 A GB871375 A GB 871375A GB 2278057 A GB2278057 A GB 2278057A GB 2278057 A GB2278057 A GB 2278057A GB 871375 A GB871375 A GB 871375A
Authority
GB
United Kingdom
Prior art keywords
oxide
filament
aluminium oxide
coating
coloration
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
Application number
GB2278057A
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.)
Telefunken AG
Original Assignee
Telefunken AG
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 Telefunken AG filed Critical Telefunken AG
Publication of GB871375A publication Critical patent/GB871375A/en
Expired legal-status Critical Current

Links

Classifications

    • 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
    • H01J9/08—Manufacture of heaters for indirectly-heated 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
    • H01J1/22—Heaters

Abstract

A heating filament suitable for an indirectly heated electrode, e.g. the cathode of a valve, has an insulating coating of aluminium oxide coloured by a relatively small quantity of metallic oxide additive which produces the coloration of the aluminium oxide by diffusion thereinto, the coloration being such as to increase the heat radiating efficiency of said filament compared with a filament having a pure aluminium oxide coating but the proportion of said other metallic oxide relative to the aluminium oxide being insufficient to reduce substantially the insulating efficiency of said coating. Metallic oxides which can produce coloration of aluminium oxide by diffusion thereinto are those which produce coloration in natural or synthetic precious stones of the corundum group, e.g. ruby and sapphire. The additive may be 0.1 to 2% of an oxide of chromium, titanium or vanadium or 0.01 to 1% of oxide of iron or cobalt. Thus the filament may be coated with a suspension of aluminium oxide (with a grain size of 1 to 35 microns) in a saturated solution of a chromium salt, e.g. chromium nitrate by spraying or dipping the filament or by spreading the suspension thereover. The coating is fixed by heating the filament to 1600-1700 DEG C. whereupon the chromium oxide is formed and diffuses into the aluminium oxide crystals to colour them red.
GB2278057A 1956-07-18 1957-07-18 Improvements in or relating to heating filaments for indirectly heated electrodes Expired GB871375A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DET12467A DE1017292B (en) 1956-07-18 1956-07-18 Aluminum oxide coating for the heating wire of indirectly heated cathodes of electrical discharge tubes and a method for producing an insulating coating on a heating wire

Publications (1)

Publication Number Publication Date
GB871375A true GB871375A (en) 1961-06-28

Family

ID=7547027

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2278057A Expired GB871375A (en) 1956-07-18 1957-07-18 Improvements in or relating to heating filaments for indirectly heated electrodes

Country Status (3)

Country Link
DE (1) DE1017292B (en)
FR (1) FR1179081A (en)
GB (1) GB871375A (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3029360A (en) * 1958-04-29 1962-04-10 Rca Corp Heater wire coating process
DE1090774B (en) * 1959-03-20 1960-10-13 Siemens Ag Heating element for indirectly heated cathodes and process for the production of an insulating coating
DE2317445C3 (en) * 1973-04-06 1982-09-09 Standard Elektrik Lorenz Ag, 7000 Stuttgart Method for manufacturing a heater for an indirectly heated cathode
DE2317446C3 (en) * 1973-04-06 1983-11-10 Standard Elektrik Lorenz Ag, 7000 Stuttgart Method of manufacturing a heating element for an indirectly heated cathode
US4151440A (en) * 1978-04-17 1979-04-24 Gte Sylvania Incorporated Cathode heater assembly for electron discharge device
DE3134505A1 (en) * 1981-09-01 1983-03-17 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Method for fabricating an emitter cathode

Also Published As

Publication number Publication date
FR1179081A (en) 1959-05-20
DE1017292B (en) 1957-10-10

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