US3127537A - Cathode mount and alloy therefor - Google Patents

Cathode mount and alloy therefor Download PDF

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Publication number
US3127537A
US3127537A US11045A US1104560A US3127537A US 3127537 A US3127537 A US 3127537A US 11045 A US11045 A US 11045A US 1104560 A US1104560 A US 1104560A US 3127537 A US3127537 A US 3127537A
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US
United States
Prior art keywords
cathode
support
alloy
tube
thickness
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
US11045A
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English (en)
Inventor
Carel W Horsting
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.)
RCA Corp
Original Assignee
RCA Corp
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
Priority to NL261666D priority Critical patent/NL261666A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US11045A priority patent/US3127537A/en
Priority to FR849173A priority patent/FR1277515A/fr
Priority to DER29580A priority patent/DE1212223B/de
Priority to CH128161A priority patent/CH395351A/de
Priority to GB4418/61A priority patent/GB961404A/en
Priority to ES0265177A priority patent/ES265177A1/es
Application granted granted Critical
Publication of US3127537A publication Critical patent/US3127537A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
    • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
    • C22C19/057—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being less 10%
    • 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
    • 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
    • H01J1/26—Supports for the emissive material

Definitions

  • This invention relates to cathode mounts and particularly to such mounts including an indirectly heated cathode supported at one end thereof in cantilever fashion and to an alloy for the core body of the cathode having relatively high hot strength and contributing to desired emission from the cathode.
  • a cathode mount comprises a sleeve type cathode supported at one end thereof in cantilever manner on one end of a first tubular support made of a material characterized by relatively low heat conductivity such as an alley commercially known as Kovar.
  • the other end portion of the tubular support is fixed to a second tubular support which is in turn fixed to a tubular terminal portion of the tube.
  • Pencil tube constructions heretofore have included a seamless cathode to provide uniform emission around the cathode, and a first tubular support having a welded seam of double thickness of the material of the support.
  • the making of the second tubular support referred to and the fixing of one end thereof to an end of the cathode, have heretofore required about forty welds.
  • Another problem area involving cathodes and supports therefor heretofore employed in Pencil type tubes relates to the space relation of the cathode to the next adjacent grid electrode.
  • all electrodes are cylindrical, so that expansions and contractions thereof occur without substantially changing initially established spacings therebetween.
  • it is desirable that the initially established spacing between the electrodes be uniform around the several electrodes. This requires that the electrodes be disposed in an exact co axial relation.
  • a difficulty has appeared in maintaining the original co-axial line-up of the tube elements. This difficulty arises as a result of the seam required in the structure of the tubular support aforementates tent tioned, engaging the cathode.
  • Such seam due to its local double material thickness, causes an asymmetric thermal distribution, which tends to result in warping of the support cylinder upon prolonged tube use and especially upon frequent on and otf-switching of the tube.
  • the double thickness also tends to induce distortion due to the fact that a triple material thickness appears at the locations where the seamed support is welded to the cathode and second support.
  • lt is an object of the invention to provide a cathode mount that avoids the problems enumerated heretofore. To this end, further objects are:
  • a cathode of the slee-ve type and a tubular support therefor constitute an integral seamless structure.
  • the structure referred to has a composition which may vary within certain ranges to be described, but in its best form includes the following materials in the approximate relative ⁇ amounts by weight indicated: 40% cobalt, 10% tungsten, 5% molybdenum, 0.2% aluminum, 0.1% carbon, 0.08% magnesium and the balance nickel. ln addition to these materials, the composition referred to may include impurities, in such small amounts that the removal thereof is diicult and commercially impractical. This material possesses the advantageous properties of contributing to good electron emission, relatively high hot strength permitting reduced thinness of the cathode, and relatively poor heat conductivity.
  • a seamless tubular structure made of this material is advantageously suited for use in a Pencil tube, wherein the structure is supported only in one end portion of an elongated envelope and has an active cathode portion in the other end portion of the envelope,
  • the seamless character of the support facilitates maintaining the cathode in exact co-axial relation with respect to a next adjacent electrode.
  • FIG. 1 shows an elevation partly in section of a Pencil type tube in which the invention is incorporated
  • FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1.
  • the Pencil tube structure shown in FIG. l includes an elongated envelope having a cylindrical anode 12 supported in one end portion of the envelope formed by a tub-ular structure 14 and constituting lthe anode terminal of the tube.
  • a cylindrical cathode 16 including an integral tubular portion 18, is supported in the other end portion of the envelope, on a tubular support 20 tixedly engaging the inner wall of a tubular structure 22 serving as the cathode terminal of the tube.
  • a cylindrical grid 24 is ⁇ fixed at one end to an annular wall 26 defining an opening 28 through a metal disc 30. The disc 30 is sealed across a glass or ceramic portion of the tube envelope formed by two relatively short tubes 32, 34.
  • the terminal portion 14 is closed by au exhaust tubulation 36 suitably pinched off to effect a vacuum tight closure.
  • the terminal portion 22 is closed in vacuum tight manner at the lower end thereof as viewed in FIG. l, by a suitable stem, not shown.
  • Two of the four prongs 38 are connected to a heater 40, and the remaining two prongs 38 are connected to a getter (not shown) within the terminal portion 2-2.
  • the prongs are adapted to be connected to suitable energizing circuits, for energizing the heater 40 and flashing the getter.
  • the cathode y16 and tubular support 1S integral therewith, constitute a seamless tube of uniform diameter and thickness throughout their lengths. Consequently, by the use of suitable jigs, not shown, the anode 12, grid 24 and cathode 16 may be yoriented in an exact co-axial relation and xed while in such orientation.
  • the integral character of the cathode and its tubular support assures freedom from tilting of the cathode 16 with respect to the grid 24 during tube operation. Such tilting, which would be occasioned by a non-symmetrical cross-section of the tubular support 18 resulting from a seamed construction, -is avoided by the cross-sectional symmetry of the suppor-t as shown in FIG. 2. Further contribution to freedom from tilting is provided by a symmetric .array of spot welds 42 between the lower free end of support 18 and the tubular support 20. Instead of spot welding, a continuous weld around the periphery of the lower end ⁇ of support 18 may be made. In either case, the welded engagement between the suppor-t 18 and support 20 is free from any -component tending to tilt the integral cathode and support structure 16, 18.
  • Such supporting means 11S is integral with the cathode 16.
  • the integral structure 16, 1S, Aformed ⁇ of seam-:less tubing, is relatively long. It extends from the support 20 -in terminal portion 22 of the tube envelope, through opening 2S yin disc 30, and into the anode 12 in terminal portion I14.
  • the cathode portion 16 of the integral structure referred to, is coated with a suitable electron emitting material 44, such as a mixture of the oxides of barium, strontium and calcium.
  • the support portion 18 of the structure is free from such coating.
  • the utilization of ⁇ a common composition for the cathode 16 and its integral support l18 requires that the composition possess a number or" properties not heretofore found in any one composition.
  • these properties are a relatively high hot strength to per-mit the support portion 18 to meet the relatively ⁇ severe support demands placed upon it by virtue of the cantilever mounting of the cathode portion 16; ability to contribute to good electron emission from the coating 44; relatively poor heat conductivity to reduce the amount of heat loss from the cathode portion 16 by conduction to the support 20 through the support portion 18 of the integral cathode and support structure; and absence of constituents which volatilize from the cathode support and into the tube envelope, and give rise to lan objectionable condition of tube operation known as bulb loading.
  • the alloy according to the invention includes in approximate amounts, 40% cobalt, 10% tungsten, 5% molybdenum, 0.2% aluminum, 0.1% carbon, 0.08% magnesium and 44.62% nickel, all by weight. In this form, the alloy has contributed to best performance of a cathode mount of the type shown in FIG. l.
  • the amounts of tungsten and molybdenum which contribute to the foregoing desirable coactions with aluminum and magnesium, are suihciently small to permit inclusion in the alloy of an appreciable amount of cobalt for further contributing to the strength of a structure made of the alloy, and to low heat conductivity thereof.
  • Cobalt adversely affects the workability of the alloy. Where the alloy is to be used in a seamless tubing structure, such Workablity must be sutiiciently high to permit normal tube drawing operations. According to the invention, therefore, the amount of cobalt is limited to an amount of from 30 to 60% by Weight of alloy.
  • the balance of the alloy consists of nickel and a relatively small amount of carbon, both of which contribute to the aforementioned desirable Workability thereof.
  • the alloy of the invention is characterized by advantages in Welding to the support 20, and certain advantages accruing as a consequence of a combination of the high structural strength of the alloy and its low heat conductivity.
  • the support portion 18 of applicants integral structure may have a thickness of about 1.1 mil Without increasing its heat conduction above that of the prior structure. Furthermore, the same thickness of 1.1 mil may characterize the cathode portion 16 of the integral structure shown in FIG. 1, Without resulting in deformation thereof. Due to the low strength of prior cathode structures, the cathode material thereof has required a thickness of about 2 mils to prevent such deformation.
  • the reduced thickness of the cathode according to the invention not only contributes to a faster heat up time of the cathode in that it avoids the thermal lag incidental to cathodes having the thicker sleeve material, but in addition, the free end portion of the structure is given a reduced mass so that it is less influenced by impact shock. This is particularly important in view of the cantilever construction of the cathode assembly. Applicant found it fortuitous that a common thickness for both a cathode and the support thereof, Was feasible with good results.
  • Such common thickness permits increased thickness of the cathode support portion 16 for improved support of the cathode, and reduced thickness of the cathode material for eliminating a top heavy condition and reducing thermal lag therein, as aforementioned.
  • the common thickness referred to also contributes to advantage in fabricating the integral structure.
  • a cathode comprising a core having a coating thereon of emitting material, said core comprising an alloy consisting by Weight and exclusive of diilicultly removable impurities, of from 30 to 60% cobalt, 0.01 to 2.0% aluminum, 2 to 25% tungsten, 2 to 25% molybdenum, 0.01 to 0.25% carbon, 0.01 to 0.10% magnesium and the remainder nickel, said alloy having relatively high hot strength, poor heat conductivity, and good effect on emission from said coating, for improved operation of said cathode.
  • a core material for an indirectly heated cathode characterized by relatively high hot strength, poor heat conductivity and contributing to good electron emission said material consisting by Weight essentially of 40% cobalt, 10% tungsten, 5% molybdenum, 0.2% aluminum, 0.1% carbon, 0.08% magnesium and the remainder nickel.
  • a cathode mount comprising a tubular sheet metal structure having a coating thereon of emitting material, and means engaging one end portion of said structure for support thereof, said structure being made of a predetermined material and said sheet metal having a predetermined thickness for contributing to reduced heat losses by conduction from said cathode to said support means, said material comprising an alloy consisting essentially by weight of from 30 to 60% cobalt, 0.01 to 2.0% aluminum, 2 to 25% tungsten, 2 to 25 molybdenum, 0.01 to 0.25% carbon, 0.01 to 0.10% magnesium and the remainder nickel, said thickness being about 1.1 mils.
  • a core for an indirectly heated cathode comprising an elongated tubular structure, said core being made of a material having a relatively high hot strength and relatively poor heat conductivity at a predetermined thickness thereof, said material consisting of by Weight in addition to diiiicultly removable traces of impurities, about 40% cobalt, about 10% tungsten, about 5% molybdenum, about 0.2% aluminum, about 0.1% carbon, about 0.08% magnesium and the remainder nickel, said thickness being about 1.1 mils.
  • an integral structure comprising a tubular cathode and a tubular support therefor, the material of said integral structure having a uniform thickness throughout its length, said material consisting of by weight, in addition to traces of ditlicultly removable impurities, about 40% cobalt, about 10% tungsten, about 5% molybdenum, about 0.2% aluminum, about 0.1% carbon, about 0.08% magnesium, and the remainder nickel, said material contributing to high hot strength and poor heat conductivity of said support, and good electron emission from said cathode.
  • An electrode support having a body formed of an alloy consisting by Weight, exclusive of impurities which are diiicult to remove, of from 30 to 60% cobalt, 2 to 25% tungsten, 2 to 25% molybdenum, 0.01 to 2.0% aluminum, 0.01 to 0.25% carbon, 0.01 to 0.10% magnesium, and the remainder nickel.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Solid Thermionic Cathode (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
US11045A 1960-02-25 1960-02-25 Cathode mount and alloy therefor Expired - Lifetime US3127537A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
NL261666D NL261666A (en, 2012) 1960-02-25
US11045A US3127537A (en) 1960-02-25 1960-02-25 Cathode mount and alloy therefor
FR849173A FR1277515A (fr) 1960-02-25 1961-01-09 Support de cathode et alliage pour un tel support
DER29580A DE1212223B (de) 1960-02-25 1961-02-02 Legierung fuer einen Kathodenschichttraeger einer Elektronenroehre
CH128161A CH395351A (de) 1960-02-25 1961-02-03 Elektronenröhre
GB4418/61A GB961404A (en) 1960-02-25 1961-02-06 Cathode mount and alloy therefor
ES0265177A ES265177A1 (es) 1960-02-25 1961-02-24 Mejoras introducidas en la fabricaciën de valvulas electrënicas

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US11045A US3127537A (en) 1960-02-25 1960-02-25 Cathode mount and alloy therefor

Publications (1)

Publication Number Publication Date
US3127537A true US3127537A (en) 1964-03-31

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US11045A Expired - Lifetime US3127537A (en) 1960-02-25 1960-02-25 Cathode mount and alloy therefor

Country Status (6)

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US (1) US3127537A (en, 2012)
CH (1) CH395351A (en, 2012)
DE (1) DE1212223B (en, 2012)
ES (1) ES265177A1 (en, 2012)
GB (1) GB961404A (en, 2012)
NL (1) NL261666A (en, 2012)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3293476A (en) * 1963-01-04 1966-12-20 Varian Associates Electrode assembly for an electron discharge device made from a material having a low carbon content
US3419744A (en) * 1964-08-17 1968-12-31 Sylvania Electric Prod Integral laminated cathode and support structure
US3524098A (en) * 1968-05-13 1970-08-11 Machlett Lab Inc Aluminum anode power tube

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105950917A (zh) * 2016-05-26 2016-09-21 张日龙 一种耐热合金及其制备方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1921619A (en) * 1928-05-21 1933-08-08 Sparks Withington Co Vacuum tube
US2445993A (en) * 1944-02-12 1948-07-27 Gen Electric Cathode structure
US2543841A (en) * 1948-06-26 1951-03-06 Midvale Company Metal alloy especially adapted for use at high temperatures
US2726346A (en) * 1952-01-25 1955-12-06 Rca Corp Indirectly heated cathode of increased efficiency
US2743175A (en) * 1953-01-27 1956-04-24 Int Nickel Co Precision casting alloy
US2899592A (en) * 1953-11-18 1959-08-11 coppola
US2945295A (en) * 1957-12-20 1960-07-19 Westinghouse Electric Corp High temperature metallic joint

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2884554A (en) * 1956-06-28 1959-04-28 Rca Corp Electron tube
DE1068387B (en, 2012) * 1956-09-03
DE1104621B (de) 1958-05-03 1961-04-13 Superior Tube Co Emissionsschichttraeger fuer indirekt geheizte Kathoden von Elektronenroehren

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1921619A (en) * 1928-05-21 1933-08-08 Sparks Withington Co Vacuum tube
US2445993A (en) * 1944-02-12 1948-07-27 Gen Electric Cathode structure
US2543841A (en) * 1948-06-26 1951-03-06 Midvale Company Metal alloy especially adapted for use at high temperatures
US2726346A (en) * 1952-01-25 1955-12-06 Rca Corp Indirectly heated cathode of increased efficiency
US2743175A (en) * 1953-01-27 1956-04-24 Int Nickel Co Precision casting alloy
US2899592A (en) * 1953-11-18 1959-08-11 coppola
US2945295A (en) * 1957-12-20 1960-07-19 Westinghouse Electric Corp High temperature metallic joint

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3293476A (en) * 1963-01-04 1966-12-20 Varian Associates Electrode assembly for an electron discharge device made from a material having a low carbon content
US3419744A (en) * 1964-08-17 1968-12-31 Sylvania Electric Prod Integral laminated cathode and support structure
US3524098A (en) * 1968-05-13 1970-08-11 Machlett Lab Inc Aluminum anode power tube

Also Published As

Publication number Publication date
GB961404A (en) 1964-06-24
CH395351A (de) 1965-07-15
DE1212223B (de) 1966-03-10
ES265177A1 (es) 1961-05-01
NL261666A (en, 2012)

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