US3853491A - Tungsten filament having uniform concentration gradient of thoria particles - Google Patents

Tungsten filament having uniform concentration gradient of thoria particles Download PDF

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Publication number
US3853491A
US3853491A US00285939A US28593972A US3853491A US 3853491 A US3853491 A US 3853491A US 00285939 A US00285939 A US 00285939A US 28593972 A US28593972 A US 28593972A US 3853491 A US3853491 A US 3853491A
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United States
Prior art keywords
tungsten
thoria
alloy
filament
percent
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Expired - Lifetime
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US00285939A
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English (en)
Inventor
T Dunham
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General Electric Co
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General Electric Co
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Publication date
Application filed by General Electric Co filed Critical General Electric Co
Priority to US00285939A priority Critical patent/US3853491A/en
Priority to FR7330601A priority patent/FR2197994B1/fr
Priority to GB4042473A priority patent/GB1451234A/en
Priority to DE732343278A priority patent/DE2343278C3/de
Priority to BE135016A priority patent/BE804110A/xx
Priority to NL7312096A priority patent/NL7312096A/xx
Priority to JP9783873A priority patent/JPS559941B2/ja
Priority to BR6820/73A priority patent/BR7306820D0/pt
Application granted granted Critical
Publication of US3853491A publication Critical patent/US3853491A/en
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Expired - Lifetime legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/40—Making wire or rods for soldering or welding
    • B23K35/402—Non-consumable electrodes; C-electrodes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • C22C32/001—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides
    • C22C32/0015—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides with only single oxides as main non-metallic constituents
    • C22C32/0031—Matrix based on refractory metals, W, Mo, Nb, Hf, Ta, Zr, Ti, V or alloys thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01K—ELECTRIC INCANDESCENT LAMPS
    • H01K1/00—Details
    • H01K1/02—Incandescent bodies
    • H01K1/04—Incandescent bodies characterised by the material thereof
    • 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
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12014—All metal or with adjacent metals having metal particles
    • Y10T428/12021—All metal or with adjacent metals having metal particles having composition or density gradient or differential porosity

Definitions

  • Thoriated tungsten materials are commonly used as incandescent filaments in electric lamps and as an electron source in such items as power tubes, electric discharge lamps and welding electrodes. It has also been recognized for some time that a higher thoria level in the tungsten material will produce a higher recrystallization temperature and greater mechanical strength. It is also well recognized for thoriated tungsten materials made by conventional powder metallurgy preparation that fabrication of the material into a filament or wire product becomes more difficult with increasing thoria level.
  • tungsten filament containing more than 1 percent by weight thoria particles with a uniform and small grain size of tungsten crystals upon recrystallization.
  • binary alloys of tungsten containing approximately 1-2 percent by weight thoria particles can be prepared in a particular manner hereinafter more fully described to provide a dispersion alloy product which following mechanical working to wire recrystallizes to smaller size and more equiaxed crystals of tungsten than can be obtained by powder metallurgy preparation. More particularly it has been discovered that upon incorporating the above specified thoria levels in a powdered compact of tungsten crystals utilizing a liquid diffusion technique described and claimed in my copending application Serial No. 186,143 there is obtained a more narrow size distribution of the thoria particles than can be obtained by preparing the compact starting with a dry blend of the alloying constituents.
  • the final tungsten wire produced in accordance with the present invention consists of a dispersion strengthened alloy having a relatively small and stable recrystallized tungsten grain size with a more uniform spacial distribution of ThO attributable to the absence of extremely large ThO particles in the precursor ingot. It is also further possible to distribute the thoria particles in a tungsten compact so that a uniform thoria concentration gradient exists with a maximum concentration being located at the exterior surface portion of the compact and with said thoria concentration continuously diminishing with increasing distance to the interior portion of said compact.
  • thoria concentration gradient can be produced in the final wire filament such that maximum thoria concentration will be located at the exterior surface portion of the filament and the thoria concentration will continuously diminish with increasing distance to the longitudinal central axis of the filament.
  • FIG. 1 are photographs taken at 2000 x magnification depicting comparative ThO distribution for 93 mil diameter rods fabricated from a binary alloy of the present invention compared with a conventional W-2 w/o ThO alloy.
  • FIG. 2 are photographs also taken at 2000 x magnification and depicting the Th distribution in a sintered compact prepared according to the present invention compared with the ThO distribution for a corresponding sintered compact prepared by a conventional powder metallurgy technique.
  • FIG. 3 are photographs depicting the recrystallized tungsten grain structures for conventional W-l w/o Th0: material compared with W-l .7 w/o ThO alloy of the present invention.
  • the liquid diffusion process practiced in the present invention comprises soaking a porous compact of tungsten particles in an inert liquid solvent for a soluble thorium compound until the porous structure of the compact is essentially filled with the solvent and thereafter immersing the solvent-filled compact in a liquid solution of the thorium compound for a sufficient time period to permit liquid diffusion of the dissolved thorium compound into at least a portion of the solvent contained in the pores of the compact.
  • the compact is then removed from the solution after a predetermined amount of liquid diffusion has taken place and all sol- I vent is removed to retain a bulk thoria concentration between approximately 1-2 percent by weight in the pores of the composite formed.
  • inert liquid solvent a solvent for the thorium compound which can be removed by drying or heating the liquidfilled compact without leaving a residue in the pore structure or undergoing any significant chemical reaction with the tungsten material.
  • inert liquid solvent a solvent for the thorium compound which can be removed by drying or heating the liquidfilled compact without leaving a residue in the pore structure or undergoing any significant chemical reaction with the tungsten material.
  • a pressed compact weighing approximately 3.0 kilograms and having a rectangular cross section of 17 mm X 22 mm with a density of 10.9 gms/cc was prepared from tungsten powder having an average particle size of 2.5 microns by conventional techniques.
  • the compact was slowly soaked in distilled water until the interconnected pore structure of the compact was saturated and the liquid-filled ingot thereafter immersed in an aqueous Th(NO solution having a concentration of 520 grams Th0: per'liter of solution.
  • the liquid diffusion process was interrupted after approximately 30 hours by removing the compact from the thorium nitrate solution.
  • the compact was next dried slowly in a vacuum oven at approximately l30F which removed most of the solvent from the pores of the compact while retaining a slight concentration gradient of the thorium additive in the pores at a bulk ThO concentration of 1.9 weight percent.
  • the thorium additive-containing compact was next subjected to a conventional presintering operation at approximately 1200C in hydrogen for two hours which converted the thorium nitrate in the pores to thorium oxide (thoria).
  • the presintered compact of the present example was then sintered in conventional fashion by passing an electrical current through the member to raise its temperature nearly to the melting point.
  • the sintering treatment was provided by suspending the presintered compact vertically between electrodes and applying electric current in graduated steps to provide for an escape of any volatile impurities in the compact.
  • Test specimens were obtained from the sintered compact which had a rectangular cross section in order to measure the thoria concentration along with the distribution and size-range of the thoria particles.
  • the test specimens were examined by known autoradiograph and extraction replica techniques.
  • the thoria concentration measured by standard X-ray techniques was approximately 2.1 weight thoria at the corner of the compact with the concentration decreasing to approximately 1.9 weight percent thoria at the center longitudinal axis of the compact.
  • the character of the thoria particle size in the present compact as observedv by examining extraction replicas in the electron microscope was also found to be significantly different than that obtained with conventional powder metallurgy preparation as shown in FIG. 2.
  • the thoria particle size range in the present material was significantly smaller than in the conventional material of the same bulk composition. Secondly, there was not found to be any significant agglomeration or segregation of thoria particles in the present material and the size of the larger thoria particles in the present material was significantly smaller than was found in the conventional material. No thoria particles having a particle size larger than approximately 4 microns diameter was observed in the examined specimen whereas it is not uncommon to see ThO particles in excess of 7 microns in conventional W materials containing 2% ThO Following the sintering step, the compact was rolled, swaged and drawn to approximately 18-mil wire in accordance with further conventional tungsten working practices.
  • the final tungsten wire was further subjected to recrystallization by passing an electrical current through the wire in a hydrogen atmosphere. More particularly, the wire was subjected for a 6-minute time period, to approximately percent of its fusion amperage which produced a smaller and more uniform tungsten grain size than is conventionally obtained for either 1 w/o or 2 w/o ThO alloys.
  • the more uniform recrystallized grain structure is a result of a smaller number of ThO particle segments aligned parallel to the wire axis in the new material.
  • a rolled member having the alloy composition deparison of tests results for the various specimens apfi d in claim 1 Pears in Table I below- A drawn filament having the alloy composition de- TABLE I YIELD STRENGTH (PSI) ULTIMATE STRENGTH (PSI) ELONGATION Present Present Present Alloy Alloy Alloy Temp 2% 1% 1.7% 2% 1% 1.7% 2% 1% (1.7% (C) T110 Tho ThO Tho Tho ThO Tho ThO It can be noted in Table I that tensile strength for the thoriated tungsten alloy product increases with an increasing level of thoria concentration.
  • a dispersion alloy member as in claim 1 having improved strength and ductility compared with a conventionally prepared dispersion alloy member of the same composition.
  • a drawn filament having the physical characteristics defined in claim 5.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Powder Metallurgy (AREA)
  • Discharge Lamp (AREA)
US00285939A 1972-09-01 1972-09-01 Tungsten filament having uniform concentration gradient of thoria particles Expired - Lifetime US3853491A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US00285939A US3853491A (en) 1972-09-01 1972-09-01 Tungsten filament having uniform concentration gradient of thoria particles
FR7330601A FR2197994B1 (xx) 1972-09-01 1973-08-23
DE732343278A DE2343278C3 (de) 1972-09-01 1973-08-28 Poröser dispersionsgehärteter Wolframsinterkörper
BE135016A BE804110A (fr) 1972-09-01 1973-08-28 Filament de tungstene perfectionne
GB4042473A GB1451234A (en) 1972-09-01 1973-08-28 Dispersion alloy product
NL7312096A NL7312096A (xx) 1972-09-01 1973-08-31
JP9783873A JPS559941B2 (xx) 1972-09-01 1973-09-01
BR6820/73A BR7306820D0 (pt) 1972-09-01 1973-09-03 Aperfeicoamento em filamento de tungstenio melhorado

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00285939A US3853491A (en) 1972-09-01 1972-09-01 Tungsten filament having uniform concentration gradient of thoria particles

Publications (1)

Publication Number Publication Date
US3853491A true US3853491A (en) 1974-12-10

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US00285939A Expired - Lifetime US3853491A (en) 1972-09-01 1972-09-01 Tungsten filament having uniform concentration gradient of thoria particles

Country Status (8)

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US (1) US3853491A (xx)
JP (1) JPS559941B2 (xx)
BE (1) BE804110A (xx)
BR (1) BR7306820D0 (xx)
DE (1) DE2343278C3 (xx)
FR (1) FR2197994B1 (xx)
GB (1) GB1451234A (xx)
NL (1) NL7312096A (xx)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4016446A (en) * 1975-01-31 1977-04-05 Westinghouse Electric Corporation Refractory-oxide-based incandescible radiators and method of making
US4086087A (en) * 1976-12-27 1978-04-25 Lisa Marie Morris Process for the preparation of powdered metal parts
US5590386A (en) * 1995-07-26 1996-12-31 Osram Sylvania Inc. Method of making an alloy of tungsten and lanthana
GB2394117A (en) * 2002-10-07 2004-04-14 Toshiba Kk Ion source, ion implantation device, and manufacturing method of semiconductor devices
US20070172378A1 (en) * 2004-01-30 2007-07-26 Nippon Tungsten Co., Ltd. Tungsten based sintered compact and method for production thereof
US7648933B2 (en) 2006-01-13 2010-01-19 Dynamic Abrasives Llc Composition comprising spinel crystals, glass, and calcium iron silicate

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3309069C1 (de) * 1983-03-14 1984-06-20 MTU Motoren- und Turbinen-Union München GmbH, 8000 München Elektrode,insbesondere fuer WIG-Schweissverfahren
JP5086503B2 (ja) * 2001-02-02 2012-11-28 株式会社東芝 トリウムタングステン線の製造方法
JP5414828B2 (ja) * 2012-04-12 2014-02-12 株式会社東芝 トリウムタングステン合金、トリウムタングステン線、トリウムタングステン線コイル、ならびに電子管用陰極構体

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1082933A (en) * 1912-06-19 1913-12-30 Gen Electric Tungsten and method of making the same for use as filaments of incandescent electric lamps and for other purposes.
US2798808A (en) * 1953-02-02 1957-07-09 Westinghouse Electric Corp Method of introducing zirconia into tungsten powder preliminary to forming electrodes
US2846339A (en) * 1953-10-21 1958-08-05 Honeywell Regulator Co Method of forming an electron emitting body
US3105290A (en) * 1958-12-18 1963-10-01 Westinghouse Electric Corp Cathode for electron discharge device
US3278281A (en) * 1957-09-13 1966-10-11 Westinghouse Electric Corp Thoriated tungsten filament or wire and method of making same
US3475159A (en) * 1967-01-16 1969-10-28 Dow Chemical Co Method for preparing tungsten powders doped with refractory metal oxides

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT261237B (de) * 1963-11-20 1968-04-10 Egyesuelt Izzolampa Verfahren zur Herstellung von zumindest einen Zusatz enthaltenden, auf pulvermetallurgischem Wege erhaltenen Metallkörpern

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1082933A (en) * 1912-06-19 1913-12-30 Gen Electric Tungsten and method of making the same for use as filaments of incandescent electric lamps and for other purposes.
US2798808A (en) * 1953-02-02 1957-07-09 Westinghouse Electric Corp Method of introducing zirconia into tungsten powder preliminary to forming electrodes
US2846339A (en) * 1953-10-21 1958-08-05 Honeywell Regulator Co Method of forming an electron emitting body
US3278281A (en) * 1957-09-13 1966-10-11 Westinghouse Electric Corp Thoriated tungsten filament or wire and method of making same
US3105290A (en) * 1958-12-18 1963-10-01 Westinghouse Electric Corp Cathode for electron discharge device
US3475159A (en) * 1967-01-16 1969-10-28 Dow Chemical Co Method for preparing tungsten powders doped with refractory metal oxides

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4016446A (en) * 1975-01-31 1977-04-05 Westinghouse Electric Corporation Refractory-oxide-based incandescible radiators and method of making
US4086087A (en) * 1976-12-27 1978-04-25 Lisa Marie Morris Process for the preparation of powdered metal parts
US5590386A (en) * 1995-07-26 1996-12-31 Osram Sylvania Inc. Method of making an alloy of tungsten and lanthana
GB2394117A (en) * 2002-10-07 2004-04-14 Toshiba Kk Ion source, ion implantation device, and manufacturing method of semiconductor devices
GB2394117B (en) * 2002-10-07 2004-09-08 Toshiba Kk Ion souce Ion implanting device and manufacturing method of semiconductor devices
US6825597B2 (en) 2002-10-07 2004-11-30 Kabushiki Kaisha Toshiba Ion source, ion implanting device, and manufacturing method of semiconductor devices
US20050057137A1 (en) * 2002-10-07 2005-03-17 Kabushiki Kaisha Toshiba Ion source, ion implanting device, and manufacturing method of semiconductor devices
US7144794B2 (en) 2002-10-07 2006-12-05 Kabushiki Kaisha Toshiba Ion source, ion implanting device, and manufacturing method of semiconductor devices
CN1294614C (zh) * 2002-10-07 2007-01-10 株式会社东芝 离子源、离子注入设备、半导体器件制造方法
US20070172378A1 (en) * 2004-01-30 2007-07-26 Nippon Tungsten Co., Ltd. Tungsten based sintered compact and method for production thereof
US7648933B2 (en) 2006-01-13 2010-01-19 Dynamic Abrasives Llc Composition comprising spinel crystals, glass, and calcium iron silicate

Also Published As

Publication number Publication date
GB1451234A (en) 1976-09-29
FR2197994A1 (xx) 1974-03-29
JPS4987167A (xx) 1974-08-21
DE2343278B2 (de) 1978-07-20
BR7306820D0 (pt) 1974-06-27
NL7312096A (xx) 1974-03-05
DE2343278A1 (de) 1974-03-21
JPS559941B2 (xx) 1980-03-13
FR2197994B1 (xx) 1976-05-07
BE804110A (fr) 1973-12-17
DE2343278C3 (de) 1979-03-08

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