US1924543A - Filament - Google Patents

Filament Download PDF

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Publication number
US1924543A
US1924543A US321844A US32184428A US1924543A US 1924543 A US1924543 A US 1924543A US 321844 A US321844 A US 321844A US 32184428 A US32184428 A US 32184428A US 1924543 A US1924543 A US 1924543A
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US
United States
Prior art keywords
filament
nickel
filaments
metal alloy
electron
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
US321844A
Inventor
Mont Allen B Du
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.)
DE FOREST RADIO Co
FOREST RADIO Co DE
Original Assignee
FOREST RADIO Co DE
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 FOREST RADIO Co DE filed Critical FOREST RADIO Co DE
Priority to US321844A priority Critical patent/US1924543A/en
Application granted granted Critical
Publication of US1924543A publication Critical patent/US1924543A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • H01J1/14—Solid thermionic cathodes characterised by the 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
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2933—Coated or with bond, impregnation or core
    • Y10T428/294—Coated or with bond, impregnation or core including metal or compound thereof [excluding glass, ceramic and asbestos]
    • 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
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31678—Of metal

Definitions

  • This invention relates in general to a metal alloy particularly adapted for use in constructing filaments for electron 'emi'ssive devices.
  • One of the objects of this invention is thepro-v vision of an alloy from which filamentsfor use in electron discharge devices maybe constructed 7 having desirable characteristics for such use.
  • Another object of this invention is the provision of filaments of this 'type .which have a higher tensile strength than filaments-of this type now known.
  • Another object of this invention is the provision of filaments made from the improved alloy having a-high electron emissivity.
  • a further object of this invention is the prochromium iron alloy.
  • This invention resides substantially in the combination, construction, and proportion of parts duction' of a gfilament composed'of a nickel as will bemore fully disclosed hereinafter.
  • Electron discharge devices employ an electronically active element generally known as a cathode. These cathodes are usually provided with a coating of highly emissive sub'st'ance which when heated throws oif electrons in large quantities.
  • the filament of this invention is made of a metal alloy and is of relatively large cross sectional area when madefor'use in apparatus of this'type and is, therefore, much more rugged, having a higher tensile strength, and acts better as a cathode by reason of the larger area-from which the electrons can be emitted. Furtherupon to dissipate as much heat as they would when employing altungsten filament"which is easily heated to a whitehot-incandescence.. The, 1 absence of this excess heat produces better opera L;
  • the filament is constructed of a metal alloy comprising nickel, chromium andxironr In the. bestpracticethe proportions arejchromium 15%, iron 20%, and nickel r
  • a metal alloy of nickel, iron and chromium inthese percentages 5 produces a filament having the characteristics at 750 degrees centigr'ade as contrasted with 2300 degrees centigrade for the usual thoriated ,tung sten filament. At 3 volts this filament gives about 0 the same emission'as theIusual thoriatedtungsten filament at full '5 volts, while the life of this. filament is several times as great as that of a corresponding thoriated tungsten filament.
  • a filament for electron discharge devices com prising a metal alloy consisting of approximately H 15% chromium, iron 20%,. and approximately 65% nickel, whereby'the filament may be effec-v tively operated as an emitter at a dull redheat;
  • coated filaments of this nature are found to have anelectroniemissivity which is three times greater than theemissivity of thoriated tungsten filament, In addition, by reason of its relatively greater size the filament is operated at a much lowerte'mperatureand, in fact, at a very dull red heat so as to be hardly visible.

Landscapes

  • Microwave Tubes (AREA)
  • Solid Thermionic Cathode (AREA)

Description

It is usual to construct thesefilaments' of some .Patentecl Au 29,a1933 .FILAMENT Allen B; Du Mont, Bloomfield, N Ji, assignor to i I De Forest Radio Company, Jersey City, 1..
. a corporation of Delaware No Drawing. Application November 7 Serial No. 321,844
'This invention relates in general to a metal alloy particularly adapted for use in constructing filaments for electron 'emi'ssive devices.
One of the objects of this invention is thepro-v vision of an alloy from which filamentsfor use in electron discharge devices maybe constructed 7 having desirable characteristics for such use.
Another object of this invention is the provision of filaments of this 'type .which have a higher tensile strength than filaments-of this type now known.
Another object of this invention is the provision of filaments made from the improved alloy having a-high electron emissivity. A further object of this invention is the prochromium iron alloy. v
"These and other objects will appear from the following disclosure are sought by means of this inventionr This invention resides substantially in the combination, construction, and proportion of parts duction' of a gfilament composed'of a nickel as will bemore fully disclosed hereinafter.
Electron discharge devices, of which the audion used in radio receiving and transmitting apparatus is an example, employ an electronically active element generally known as a cathode. These cathodes are usually provided with a coating of highly emissive sub'st'ance which when heated throws oif electrons in large quantities.
metal such as nickel or platinum which is coated with the elctron emissivesubstance. Filaments of .nickel or platinum, however, have many dis- T advantages, such as extremely small cross sectionalarea when constructed for the correct cur;
.rentcarryingcapacities for use on voltages now common in operating radio receiving and transmitting apparatus, and as a result are very 40 fragile. r i 1 a The filament of this invention is made of a metal alloy and is of relatively large cross sectional area when madefor'use in apparatus of this'type and is, therefore, much more rugged, having a higher tensile strength, and acts better as a cathode by reason of the larger area-from which the electrons can be emitted. Furtherupon to dissipate as much heat as they would when employing altungsten filament"which is easily heated to a whitehot-incandescence.. The, 1 absence of this excess heat produces better opera L;
ating characteristics.- j '1 9 The filament is constructed of a metal alloy comprising nickel, chromium andxironr In the. bestpracticethe proportions arejchromium 15%, iron 20%, and nickel r A metal alloy of nickel, iron and chromium inthese percentages 5 produces a filament having the characteristics at 750 degrees centigr'ade as contrasted with 2300 degrees centigrade for the usual thoriated ,tung sten filament. At 3 volts this filament gives about 0 the same emission'as theIusual thoriatedtungsten filament at full '5 volts, while the life of this. filament is several times as great as that of a corresponding thoriated tungsten filament.
It is, of course, to be understood that'good results'can be secured inaccordancewith this inf vention'by varying the proportions given and I do not, therefore. desire -to' be structurally limited to the exact-proportions given but to a range of equivalent proportions which produce a filament of substantially the same characteristics.
' What I seek to'secureby United States Let- 'ters'Patent is: j g A filament for electron discharge devices com prising a metal alloy consisting of approximately H 15% chromium, iron 20%,. and approximately 65% nickel, whereby'the filament may be effec-v tively operated as an emitter at a dull redheat;
. and a coating of electron emissivematerial on 0 more, coated filaments of this nature are found to have anelectroniemissivity which is three times greater than theemissivity of thoriated tungsten filament, In addition, by reason of its relatively greater size the filament is operated at a much lowerte'mperatureand, in fact, at a very dull red heat so as to be hardly visible. The
result is thatdevices of this nature are not called
US321844A 1928-11-26 1928-11-26 Filament Expired - Lifetime US1924543A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US321844A US1924543A (en) 1928-11-26 1928-11-26 Filament

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US321844A US1924543A (en) 1928-11-26 1928-11-26 Filament

Publications (1)

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US1924543A true US1924543A (en) 1933-08-29

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US321844A Expired - Lifetime US1924543A (en) 1928-11-26 1928-11-26 Filament

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2830917A (en) * 1954-06-07 1958-04-15 Bell Telephone Labor Inc Cathode for electron discharge devices

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2830917A (en) * 1954-06-07 1958-04-15 Bell Telephone Labor Inc Cathode for electron discharge devices

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