US3411959A - Method for producing tantalum carbide and tantalum-alloy carbide filaments - Google Patents

Method for producing tantalum carbide and tantalum-alloy carbide filaments Download PDF

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Publication number
US3411959A
US3411959A US535815A US53581566A US3411959A US 3411959 A US3411959 A US 3411959A US 535815 A US535815 A US 535815A US 53581566 A US53581566 A US 53581566A US 3411959 A US3411959 A US 3411959A
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United States
Prior art keywords
filament
tantalum
carbon
temperature
carbide
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Expired - Lifetime
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US535815A
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English (en)
Inventor
Corth Richard
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Philips North America LLC
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Westinghouse Electric Corp
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Filing date
Publication date
Priority to US436567A priority Critical patent/US3411969A/en
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to US535815A priority patent/US3411959A/en
Priority to GB5324/67A priority patent/GB1116617A/en
Priority to NL6702320A priority patent/NL6702320A/xx
Priority to DE19671558712 priority patent/DE1558712A1/de
Priority to BE695874D priority patent/BE695874A/xx
Priority to FR99699A priority patent/FR1516586A/fr
Application granted granted Critical
Publication of US3411959A publication Critical patent/US3411959A/en
Assigned to NORTH AMERICAN PHILIPS ELECTRIC CORP. reassignment NORTH AMERICAN PHILIPS ELECTRIC CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: WESTINGHOUSE ELECTRIC CORPORATION
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/20—Carburising
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/90—Carbides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/90—Carbides
    • C01B32/914—Carbides of single elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01K—ELECTRIC INCANDESCENT LAMPS
    • H01K3/00—Apparatus or processes adapted to the manufacture, installing, removal, or maintenance of incandescent lamps or parts thereof
    • H01K3/02—Manufacture of incandescent bodies
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases

Definitions

  • This invention relates generally to the production of tantalum carbide filaments and, more particularly, to a method for producing improved tantalum carbide and tantalum-alloy carbide filaments which are strong, distortion free and relatively elastic.
  • Tantalum carbide and tantalum-alloy carbide filaments for incandescent lamps are known in the art. When operated in a gaseous atmosphere comprising halogen, hydrogen and carbon, for example, such filaments can be operated at a very high true temperature, such as from 3300 K. to 3700 K. This operating temperature range approaches and actually exceeds the melting point of tungsten per se (3643 K.) and is far above the normal operating temperature of tungsten filaments. This makes a tantalum carbide or tantalum-alloy carbide filament particularly useful in applications such as projection lamps where it is desirable to operate the lamp in as bright a manner as possible commensurate with even a relatively short life.
  • Tantalum carbide and tantalum-alloy carbide filaments are extremely brittle and cannot be formed into a coil or otherwise bent.
  • the filaments are subject to distortion during operation, which coupled with their usual brittleness re- 7 suits in excessive breakage.
  • the brittleness also results in breakage when mounting the filament as well as breakage due to the usual shocks encountered during shipment of the lamps and handling of same after they are put into use.
  • tantalum carbide or tantalumalloy carbide filaments have not become any appreciable factor in the field of illumination such as projection lamps, in spite of the tremendous gains which can be achieved in brightness of operation because of the high operating temperatures which can be used.
  • the filament has been mounted in the completed lamp as a metallic member, and thereafter converted to tantalum carbide. This is very impractical from a commercial standpoint.
  • the foregoing objects of the invention, and other objects which will become apparent as the description proceeds, are achieved by supporting on a carbon member a filament of tantalum metal or a refractory tantalum-containing alloy.
  • the metal filament has previously been coiled into its final, desired form and preferably is stress relieved after coiling.
  • the supported coiled filament is initially heated on the support member in an atmosphere consisting essentially of carbon as the only reactive constituent at a predetermined temperature below the eutectic melting point of the filament as partially carbided, but which heating temperature is sufiicient to cause carbon to readily diffuse into the filament.
  • This initial heating temperature is maintained for a time sufficient to perice mit carbon to be diffused into the filament in an amount which is in excess of that carbon content required to form a tantalum-carbon eutectic. This increases the filament melting temperature. Thereafter, the support member and supported filament are heated in a similar atmosphere to a final temperature which is greater than the melting temperature of the tantalum-carbon eutectic, but less than the melting temperature of the now partially carbided filament. This final heating temperature is maintained for a sufiicient time to diffuse additional carbon into the filament to form stoichiometric tantalum carbide or tantalum-alloy carbide. The completely carbided filament is then cooled under non-reactive conditions.
  • FIGURE 1 is a flow diagram illustrating the basic steps of the present method
  • FIG. 2 is a plan view of a graphite block such as is used as a filament support member, with a tantalum or tantalum-alloy metallic coiled filament supported therein;
  • FIG. 3 is an elevational view of FIG. 1;
  • FIG. 4 is a plan view of an alternative graphite support member wherein plural grooves are provided in a surface thereof to support a plural-coil filament;
  • FIG. 5 is an isometric view, partly broken away, showing a plurality of support members in heating position in a carbon crucible, wherein the support members are stacked for heating in accordance with the present method.
  • the filament of the present invention will normally have a coiled configuration since the best applications for high brighteners light sources are those which require the light to be concentrated.
  • filament coil 10 such as shown in FIGS. 2 and 3.
  • the coil 10 is preferably formed of an alloy of tantalum and 10% tungsten by weight.
  • the coil 10 could be formed of tantalum metal or other refractory tantalum-containing alloys which contain a major percentage of tantalum. In this regard, see the alloys referred to in US. Pattent 3,219,493, dated Nov. 23, 1965.
  • the coil 10 is placed into a carbon supporting member 12 which preferably is formed of graphite.
  • the filament is positioned within a groove 14 which is provided in the top surface of the graphite supporting member.
  • the supported filament 10 and graphite support member 12 are placed into a carbon crucible and the filament heated under nonreactive conditions to a relatively low temperature in order to relieve the winding stresses which are introduced into the filament during coiling.
  • the stress-relieving temperature may be varied considerably depending upon the Wire dimensions, but for a lO-rnil diameter wire, which wire size will be considered in detail hereinafter, the filament is stress relieved by heating to a temperature of about 1500 C. for about 15 minutes in either a vacuum or an inert gas atmosphere, such as argon.
  • the supported filament 10 and the supporting memer 12 are heated in a carbon crucible in an atmosphere consisting essentially of carbon as the only reactive constitutent at a predetermined temperature which is below the eutectic melting temperature of tantalum-carbon (2800 C.), but which is sufficient to cause carbon to diffuse into the filament in total amount less than that required to form stoichiometric tantalum carbide.
  • Suflicient carbon is diffused into the filament during the initial heating, however, to exceed that carbon content required to form a tantalum-carbon eutectic and also to raise the filament melting temperature to substantially more than the eutectic melting temperature.
  • the lO-mil wire is heated in an argon atmosphere to a temperature of from 2600" C. to 265G C. for a period of about 30 minutes. It should be understood that these initial heating conditions can be varied considerably depending upon the wire dimensions and the time available to diffuse carbon into the coil, which of course is a commercial consideration.
  • tantalum-carbon eutectic when carbon is diffused into tantalum, a small amount of diffused carbon will cause the resulting material to exhibit a eutectic melting point at approximately 2800 C.
  • a preformed tantalum filament is bein carbided, gross distortion will occur if incipient melting or any melting occurs. Apparently the melting creates a structure which makes the resulting tantalum carbide extremely brittle.
  • carbon is initially difiuscd into the tantalum or tantalum-alloy filament at a temperature which is slightly below this eutectic melting temperature and the initial heating and resulting carbon diffusion into the filament is continued until carbon is present in the filament in suflicient amount that the melting point of the resulting tantalum-carbon filament is substantially more than the eutectic melting temperature.
  • the initially heated and partially carbided filament has a melting temperature greater than 3,100 C.
  • the support member 12 and supported filament 10 are rapidly heated to a final heating temperature in excess of the melting temperature of the eutectic, but less than the melting temperature of the now partially carbided filament, and this final heating temperature is maintained for a predetermined period of time which is sufiicient to cause additional carbon to diffuse into the filament to form a stoichiometric tantalum carbide.
  • the final heating temperature is at least 3,000 C.
  • a IO-mil partially carbided filament is heated in the final heating step at a temperature of 3100 C. for a period of 30 minutes, which is sufiicient to form a stoichiometric tantalum-tungsten carbide.
  • the initial and final heating steps are conducted in the atmosphere consisting essentially of carbon as the only reactive element, preferably with an inert gas surrounding atmosphere, argon being preferred.
  • the completely carbided filament is cooled under non-reactive conditions, such as an argon atmosphere or vacuum, to a temperature 'at which the filament will not oxidize.
  • non-reactive conditions such as an argon atmosphere or vacuum
  • the foregoing 10 mil filament is cooled under the nonreactive conditions to a temperature less than about 100
  • FIG. 5 there is shown a fourbarrel coiled filament 16 wherein the individual filamentary coils 18 are placed into plural grooves 20 provided in a graphite supporting member 22.
  • the uncoiled connecting sections 24 of the filament 18 project slightly from the edge portions of the graphite support 22.
  • the support member 22 is particularly adapted to be nestled or stacked for production runs so that many filaments can be heat treated at the same time.
  • FIG. 5 There is also shown in FIG. the carbon crucible 26, partly broken away, in which the support members 22 are stacked.
  • the crucible 26 is placed into a conventional, electrically or induction-heated furnace which has a controlled argon atmosphere and the carbiding steps can be completed in one sequential operation. Any other inert atmosphere or even a vacuum could be maintained in the furnace during the heating steps.
  • the stress relief, initial heating step and final heating step are sequentially performed with no cooling between each step.
  • the specific schedule as outlined hereinbefore can be varied considerably depending on the size of the wire being carbided. While the stress relief step is very desirable, it can be dispensed with if desired.
  • Filaments which have been carbided in accordance with the present method are extremely strong and distortion free, as well as relatively elastic. Such filaments have been operated in projection lamps for a period of 30 hours at a true temperature of 3700 K. This is in contrast to the usual projection lamp which operates at a true temperature of about 3225 K.
  • the preferred mode for mounting the filament in a projection lamp or other incandescent source is disclosed in copending application Ser. No. 535,- 835, filed concurrently herewith, entitled Tantalum Carbide or Tantalum-Alloy Carbide Filament Mounting and Method by the present inventor and owned by the present assignee.
  • present filaments are in conjunction with projection lamps, it should be understood that the present filaments can be used in conjunction with any type of high-intensity light source,
  • said initial heating temperature is less than 2800 C., and said final heating temperatureis more than 3000 C.
  • said filament is formed prior to initial heating as a plurality of coils each connected by an uncoiled filamentary member, and said carbon support member is a graphite block having plural open grooves provided in a surface thereof to receive said plural coil of said filament.
  • said filament prior to said initial heating is formed into its desired final configuration which is that of a coil, said coil is placed into an open groove provided in a surface of a graphite member, and said graphite member and said coil are then heated under non-reactive conditions to a temperature of about 1500 C. for about fifteen minutes to stress relieve said filament coil.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Carbon And Carbon Compounds (AREA)
US535815A 1965-03-02 1966-03-21 Method for producing tantalum carbide and tantalum-alloy carbide filaments Expired - Lifetime US3411959A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US436567A US3411969A (en) 1965-03-02 1965-03-02 Method and apparatus for heat sealing cartons
US535815A US3411959A (en) 1966-03-21 1966-03-21 Method for producing tantalum carbide and tantalum-alloy carbide filaments
GB5324/67A GB1116617A (en) 1966-03-21 1967-02-03 Method for producing tantalum carbide and tantalumalloy carbide filaments
NL6702320A NL6702320A (pm) 1966-03-21 1967-02-16
DE19671558712 DE1558712A1 (de) 1966-03-21 1967-02-21 Verfahren zur Herstellung von Heizfadenmaterialien
BE695874D BE695874A (pm) 1966-03-21 1967-03-21
FR99699A FR1516586A (fr) 1966-03-21 1967-03-21 Fabrication de filaments en carbure de tantale

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US535815A US3411959A (en) 1966-03-21 1966-03-21 Method for producing tantalum carbide and tantalum-alloy carbide filaments

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US3411959A true US3411959A (en) 1968-11-19

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US535815A Expired - Lifetime US3411959A (en) 1965-03-02 1966-03-21 Method for producing tantalum carbide and tantalum-alloy carbide filaments

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US (1) US3411959A (pm)
BE (1) BE695874A (pm)
DE (1) DE1558712A1 (pm)
GB (1) GB1116617A (pm)
NL (1) NL6702320A (pm)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3523044A (en) * 1968-01-18 1970-08-04 Westinghouse Electric Corp Method of carbiding tantalum or tantalum alloy and filament
US3523207A (en) * 1968-01-18 1970-08-04 Westinghouse Electric Corp Incandescent lamp with tantalum carbide filament and nitrogen gas atmosphere
US3650850A (en) * 1970-04-07 1972-03-21 Richard Corth Method of making an undistorted coiled-coil tantalum carbide filament
US4275025A (en) * 1977-05-02 1981-06-23 Ppg Industries, Inc. Refractory metal diboride articles by cold pressing and sintering

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7440346B2 (ja) * 2020-06-01 2024-02-28 株式会社アルバック 通電加熱線の製造方法および製造装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2410060A (en) * 1942-03-11 1946-10-29 Standard Telephones Cables Ltd Method of producing vacuum tube electrodes
US3113893A (en) * 1960-10-14 1963-12-10 Sylvania Electric Prod Incandescent filament
US3219493A (en) * 1962-02-05 1965-11-23 Polaroid Corp Method of making electric lamps
US3266948A (en) * 1963-10-10 1966-08-16 Joseph C Mcguire Carbide deposition on tantalum

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2410060A (en) * 1942-03-11 1946-10-29 Standard Telephones Cables Ltd Method of producing vacuum tube electrodes
US3113893A (en) * 1960-10-14 1963-12-10 Sylvania Electric Prod Incandescent filament
US3219493A (en) * 1962-02-05 1965-11-23 Polaroid Corp Method of making electric lamps
US3266948A (en) * 1963-10-10 1966-08-16 Joseph C Mcguire Carbide deposition on tantalum

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3523044A (en) * 1968-01-18 1970-08-04 Westinghouse Electric Corp Method of carbiding tantalum or tantalum alloy and filament
US3523207A (en) * 1968-01-18 1970-08-04 Westinghouse Electric Corp Incandescent lamp with tantalum carbide filament and nitrogen gas atmosphere
US3650850A (en) * 1970-04-07 1972-03-21 Richard Corth Method of making an undistorted coiled-coil tantalum carbide filament
US4275025A (en) * 1977-05-02 1981-06-23 Ppg Industries, Inc. Refractory metal diboride articles by cold pressing and sintering

Also Published As

Publication number Publication date
GB1116617A (en) 1968-06-06
BE695874A (pm) 1967-09-01
NL6702320A (pm) 1967-09-22
DE1558712A1 (de) 1970-04-23

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Owner name: NORTH AMERICAN PHILIPS ELECTRIC CORP.

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:WESTINGHOUSE ELECTRIC CORPORATION;REEL/FRAME:004113/0393

Effective date: 19830316