EP0073814B1 - Fil en alliage pour composants de lampes et lampes le comprenant - Google Patents

Fil en alliage pour composants de lampes et lampes le comprenant Download PDF

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Publication number
EP0073814B1
EP0073814B1 EP82901088A EP82901088A EP0073814B1 EP 0073814 B1 EP0073814 B1 EP 0073814B1 EP 82901088 A EP82901088 A EP 82901088A EP 82901088 A EP82901088 A EP 82901088A EP 0073814 B1 EP0073814 B1 EP 0073814B1
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EP
European Patent Office
Prior art keywords
filament
lamp
incandescent lamp
tungsten
alloy wire
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
EP82901088A
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German (de)
English (en)
Other versions
EP0073814A4 (fr
EP0073814A1 (fr
Inventor
Raman L. Daga
Thomas J. Patrician
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.)
Osram Sylvania Inc
Original Assignee
GTE Products Corp
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Filing date
Publication date
Application filed by GTE Products Corp filed Critical GTE Products Corp
Publication of EP0073814A1 publication Critical patent/EP0073814A1/fr
Publication of EP0073814A4 publication Critical patent/EP0073814A4/fr
Application granted granted Critical
Publication of EP0073814B1 publication Critical patent/EP0073814B1/fr
Expired legal-status Critical Current

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Classifications

    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J7/00—Details not provided for in the preceding groups and common to two or more basic types of discharge tubes or lamps
    • H01J7/14—Means for obtaining or maintaining the desired pressure within the vessel
    • H01J7/18—Means for absorbing or adsorbing gas, e.g. by gettering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01K—ELECTRIC INCANDESCENT LAMPS
    • H01K1/00—Details
    • H01K1/18—Mountings or supports for the incandescent body

Definitions

  • the present invention relates to alloy wire, lamp components made therefrom and lamps incorporating the components.
  • U.S. patent 1,602,526 to Gero describes the doping of tungsten oxide powders with potassium to promote a recrystallized structure having elongated interlocking crystals.
  • U.S. patent 3,236,699 to Pugh et al relates to a tungsten alloy doped with potassium and silicon in the form of a filament having good ductile properties and sag resistance in the recrystallized state.
  • U.S. patent 3,748,519 to Martin et al relates to supports for tungsten filaments and gettering.
  • An alloy disclosed therein includes 92.5 percent tantalum and 0.5 tungsten.
  • U.S. patent 1,508,241 to Pacz describes a non-sag filament which uses oxides of tantalum or niobium as dopants in place of sodium potassium silicates to produce a non-sag filament.
  • U.S.-patent 3 346 761 to Ackermann describes a tungsten wire into whose surface layer tantalum is diffused serving as a getter.
  • the alloy wire composition of the present invention has metallurgical properties which permit its use as various components in various types of lamps.
  • the metallurgical properties vary depending on the method of manufacture and use.
  • the alloy wire may be used as a non-sag filament, a vibration resistant filament, a filament support or gettering means.
  • an alloy wire consisting of a single phase solid solution of tungsten and 0.2 to 6 percent by weight tantalum, said alloy including grain controlling additives uniformly distributed therein, said additives consisting of from 30 to 200 parts per million potassium and less than 100 parts per million silicon.
  • a filament for an incandescent lamp an incandescent lamp and method for making the alloy wire.
  • the stability of the fine grain structure at temperatures up to at least 2200 degrees centigrade make it suitable for use in incandescent lamps requiring a vibration resistance filament.
  • the recrystallized structure having elongated grains is suitable for use in high temperature lamps requiring a sag resistance filament. Due to the inclusion of tantalum the alloy of the present invention has properties which make it suitable for use as a gettering component in lamps, such as tungsten- halogen lamps.
  • the alloy of the present invention consists of tungsten and from 0.2 to 6 percent by weight tantalum. More preferably tantalum is present in an amount from about 1 to about 4 percent by weight based on total weight of the alloy.
  • the alloy is intentionally doped with grain controlling additive to promote the formation of a favorable grain structure.
  • the additives are preferably present in amounts less than about 300 parts per million and consist essentially of from about 20 to about 200 parts per million potassium and less than about 100 parts per million silicon. Silicon is present primarily to aid in the retention of potassium during processing. It has been found that potassium is more preferably present in an amount from about 30 to about 100 parts per million based on the weight of the final alloy composition.
  • impurities may deleteriously affect the desired properties of the final alloy. It is desirable to maintain the impurities at amounts less than about 100 parts per million and preferably less than about 50 parts per million by weight based on the total weight of the alloy. Typical impurities include aluminum, calcium, copper, iron, chromium, magnesium, manganese, nickel, tin, sodium and molybdenum. Impurities may be present despite all efforts to achieve high purity alloy material. It is most preferred that each of the impurities be less than about 5 parts per million.
  • the amount of minor ingredients including additives and impurities is based on the total weight of the alloy and is dependent on the metal source used, the temperature and time of sintering and other process steps.
  • the amount of dopant employed in the presintered powder is at least equal to the amount desired in the final product and possibly up to 10 times the amount.
  • the alloys of the present invention are prepared by powder metallurgical techniques wherein component powders are intimately mixed to an extent to assure the homogeneity of the final alloy.
  • the powder mix is compacted to form an ingot and the ingot is sintered under conditions which result in the formation of a single phase solid solution of tungsten and tantalum.
  • the sintered ingots are mechanically worked and further reduced in size by rolling, swaging, drawing and annealing to obtain a wire alloy having the desired metallurgical structure.
  • the alloy wire has a fine grain structure stable at a temperature of about 2300 centigrade.
  • the fine grain structure is recrystallized to a grain structure having large grains extending in the longitudinal direction of the wire. A temperature of greater than about 2500 degrees centigrade is needed to promote the recrystallization to the desirable large grain structure.
  • the alloy wire of the present invention retains the fine grain structure at higher temperatures.
  • Figure 2 illustrates the grain structure when conventional doped tungsten wire is annealed at 2300C to form large elongated grains.
  • Figure 3 the same anneal at 2300C does not result in the formation of a large grain structure but instead retains a fine grain structure.
  • the number of grains across the cross section of the wire is very large. Retention of the fine grain structure at high temperatures is useful for lamp filaments requiring a vibration resistant structure.
  • the fine grain structure of the alloy wire of the present invention may be recrystallized to a large grain structure similar to the structure shown in Figure 2.
  • the grain growth proceeds primarily in the longitudinal direction of the wire and results in coarse, interlocked grains and irregular grain boundaries which form, on the average, very small angles with the surfaces of the wire.
  • This grain structure is effective in preventing sag in lamp filaments which is primarily offsetting of grains due to slip in grain boundaries forming large angles with the wire surfaces.
  • the alloy of the present invention is ideally suited for sag resistant filaments for electronic lamps and tubes which are operated at temperatures above which recrystallization occurs.
  • tantalum in addition to the beneficial metallurgical properties, permits its use as lamp components which are operated at a suitable temperature to enhance the gettering properties of tantalum. It is known that tantalum reacts with oxygen; hydrogen and halides at high temperatures. It is theorized that the resulting compounds formed by tantalum gettering may further stabilize the alloy wire grain structure due to the formation of dispersed tantalum compounds which inhibit changes in grain structure.
  • the alloy of the present invention possesses suitable ductility, tensile strength and electrical resistivity that contribute to the suitability for use as a component in a lamp.
  • FIG. 1 is illustrative of an incandescent lamp and lamp components utilized therewith.
  • the lamp has a hermetically sealed light transmitting envelope 2.
  • a coiled filament 6 is supported within the envelope 2 by a pair of lead-in wire 10 extending through the envelope 2 and sealed into the flat pinch 4.
  • the filament 6 which spans the inner ends of the lead-in wires 10 is clamped at positions 14 and 16.
  • Lead-in wires 10 have terminal portions 22 which protrude endwise from the outer end of the lamp. Outwardly of the flat pinch 4, the terminal portions 22 of the lead-in wires 10 are bend back to form double-legged contact members 24.
  • a filament support is shown at 26.
  • the fine grain structure of the present invention which is stable at filament temperatures up to 2200 degrees centigrade is particularly desirable when used as the filament component 8.
  • the envelope 2 is filled with an inert gas, such as argon, nitrogen, krypton or mixture thereof, and a halogen additive such as bromine, for example, in the form of hydrogen bromine.
  • an inert gas such as argon, nitrogen, krypton or mixture thereof
  • a halogen additive such as bromine, for example, in the form of hydrogen bromine.
  • the total pressure of the admixed halogen and inert fill gas may range from 2 to about 7 atmospheres, at room temperatures, depending on the fill gas composition, voltage, lumen and life ratings for which the lamp is designed.
  • the filament may be a coiled filament or a coiled coil filament which is operated at relatively high temperatures and which is desirably sag resistant.
  • the elongated large grain alloy structure of the present invention is suitable for use in lamps of the halogen type and in lamps of the arc discharge type. When used as a filament in a halogen lamp, the alloy wire of the present invention is operated at temperatures above the temperatures at which the gettering properties of the alloy are most favorably utilized.
  • the gettering properties of the alloy of the present invention are utilized most effectively when the alloy is used as a lower temperature component of the lamp such as the lead-in wires 10 or filament support 26.
  • the alloy of the present invention prior to coiling into filament typically has a tensile strength of from about 200 to 300 kilograms per square millimeter. More preferably, the tensile strength is greater than about 210 kilograms per square millimeter and most preferably greater than about 250 kilograms per square millimeter.
  • the relatively high tensile strength contributes to the use of the alloy for applications relating to halogen lamps and contributes to the workability of the alloy material permitting the formation of wire.
  • the coefficient of expansion of the alloy of the present invention as measured at about 20°C is from about 4.3 to about 4.5x10- 6 cm./cm. °C and more preferably the coefficient of expansion is from about 4.3 to about 4.4x10- 6 cm./cm. °C.
  • the alloy typically has an electrical resistivity of about 5.5 to about 6.0 microhm -cm. at 0°C.
  • the electrical resistivity is less than about 5.7 microhm -cm. and more preferably less than about 5.6 microhm -cm.
  • the lead wire preferably has a circular cross section with a diameter of from about 0.25 millimeters to about 0.81 millimeters.
  • the wire size depends to some extent on the power rating of the lamp with larger diameters being preferred for higher wattage lamps.
  • substantially pure tungsten powder doped with grain controlling additives consisting essentially of potassium and silicon is mixed with substantially pure tantalum powder, the resulting powder mix is compacted to form an ingot which is sintered in a hydrogen atmosphere for a sufficient period of time and at a sufficient temperature to form a solid phase solution of tungsten and tantaium.
  • the resulting ingot is mechanically worked into an alloy wire.
  • the dopants are preferably added to tungsten oxide prior to reduction to the tungsten powder.
  • the dopants may be in any convenient form of potassium, aluminum and silicon such as silicon dioxide, alumina and potassium chloride. Potassium silicate is a preferred dopant since it serves as a source for both potassium and silicon.
  • the percent by weight of aluminum in the doping compounds as expressed in terms of equivalent aluminum trioxide is preferably about 0.04% by weight of tungsten oxide.
  • the percent by weight of potassium in the doping compounds, as expressed in terms of equivalent potassium oxide is preferably about 0.3% by weight of tungsten oxide.
  • the percent by weight of silicon in the doping compounds, as expressed in terms of equivalent silicon dioxide is preferably about 0.4% by weight of tungsten oxide.
  • Pure tantalum powder milled to obtain a fine particle size on the order of a Fisher Sub-Sieve Size of from about 5.0 microns to about 14.0 pm is mixed with the doped tungsten powder to produce powder blends having from about 0.2 to about 6 percent by weight tantalum.
  • the blending operation is performed so as to yield a very uniformly blended doped tungsten-tantalum powder.
  • the resulting doped tungsten-tantalum is presintered in an inert atmosphere at about 1300°C.
  • the ingot is next; sintered in an inert gas or hydrogen atmosphere by direct electric current resistance heating.
  • the sintering is performed by a stepwise increase in current until a final temperature of about 2900°C is achieved.
  • the final temperature is held for a sufficient period of time, typically on thdsorder of about 15 minutes to achieve a single phase solution of tungsten and tantalum and densification of ingot. It has been found that alloys of the present invention which have been sintered to at least about 90 percent, and more preferably to at least about 95 percent of their theoretical density (as calculated by the rule of mixtures) are sufficiently sintered to yield the solid solution.
  • the resulting ingot is mechanically worked by known methods using multiple swaging steps which successively reduce the cross-sectional area and intermediate annealing steps which improve mechanical workability.
  • Annealing steps are preferably performed in a hydrogen atmosphere.
  • the material is further reduced by drawing, through a series of successive reductions.
  • About 400 grams of commercially pure tantalum powder, KBI, Lot W1110, particle size of about 7.2 pm and about 19.6 kilograms of the doped tungsten powder are mixed in a blender for about one hour.
  • a portion of the resulting mixture was compacted at a pressure of about 30,000 psi (2000 bar) to form an ingot.
  • the compacted ingot was presintered at a temperature of about 1300°C in a vacuum at a pressure of about 1.3x10- 2 pascals in a furnace.
  • the ingot or rod was direct resistance sintered at 2700 to 2900°C for 15 minutes.
  • the resulting density is about 17.6 g/cm 3 .
  • the ingot was swaged to a diameter of about 3 mm at temperture of 1600°C to 1300°C and annealed at about 2200°C at various intermediate sizes.
  • Wire drawing from 3.3 mm diameter resulted in a size reduction to lamp wire sizes varying between 0.5 mm to 0.01 mm and was carried out at temperatures from 1000°C to 500°C in several drawing steps.
  • the tensile strength of the wire at 0.5 mm was 2370 N/mm 2 .
  • Wire drawn to substantial smaller sizes for use as filament material will have tensile strength ranging from 2200 to 4000 N/mm 2 depending on the size and the proximity of that size to an in-process anneal. Filament wires as small as 0.01 mm are common.

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  • Discharge Lamp (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Powder Metallurgy (AREA)

Claims (28)

1. Un fil en alliage comprenant essentiellement une solution solide en phase unique de tungstène et entre 0,2 et 6% environ en poids de tantale, le dit alliage incluant des additifs de contrôle des grains uniformément répartis à l'intérieur, les dits additifs comprenant entre 30 et 200 parts par million de potassium et moins de 100 parts par million de silicium.
2. Un fil en alliage selon la revendication 1 caractérisé en ce qu'il comprend une structure en grains fins stable à une température de 2300°C environ.
3. Un fil en alliage selon la revendication 2 caractérisé en ce qu'il comprend entre 2 et 4% en poids environ de tantale.
4. Un fil en alliage selon la revendication 1 caractérisé. en ce que la structure en grains comprend des grains importants s'étendant dans le sens longitudinal du fil.
5. Un fil en alliage selon la revendication 4 caractérisé en ce que la dite structure en grains est réalisée par recristallisation d'une structure en grains fins à une température supérieure à 2500°C environ.
6. Un filament pour lampes à incandescence consistant essentiellement en une solution solide en phase unique de tungstène et entre 0,5 et 6% en poids environ de tantale, le dit filament incluant des additifs de contrôle des grains uniformément distribués à l'intérieur, les dits additifs comprenant entre 30 et 200 parts par million en poids de potassium et moins de 100 parts par million en poids de silicium.
7. Un filament selon la revendication 6 présentant une structure en grains fins résistant aux vibrations, la dite structure en grains étant stable aux températures de fonctionnement du filament jusqu'à au moins 2200°C.
8. Un filament selon la revendication 7 caractérisé en ce qu'il présente une section de forme substantiellement circulaire et un diamètre comprise entre 0,01 et 0,5 millimêtre environ.
9. Un filament selon la revendication 8 caractérisé en ce qu'il affecte la forme d'une bobine.
10. Un filament selon la revendication 6 caractérisé en ce qu'il comprend une structure en grains résistant à la pliure comportant des grains importants s'étendant dans le sens longitudinal du fil.
11. Un filament selon la revendication 10 caractérisé en ce que la structure en grains résistant à la pliure est obtenue par recristallisation d'une structure en grains fins à une température supérieure à 2500°C environ.
12. Un filament selon la revendication 11 caractérisé en ce qu'il présente une section de forme substantiellement circulaire et une diamètre compris entre 0,01 et 0,5 millimêtre environ.
13. Un filament selon la revendication 12 caractérisé en ce qu'il affecte la forme d'une bobine.
14. Un filament selon la revendication 12 caractérisé en ce qu'il affecte la forme d'une bobine bobinée.
15. Une lampe à incandescence comprenant une ampoule transparente, un filament à l'intérieur de la dite ampoule, et des entrées de courant reliées au dit filament et scellées dans la dite ampoule, la dite lampe à incandenscence incluant un composanttel qu'un fil en alliage consistant en une solution solide en phase unique de tungstène et entre 0,2 et 6% en poids environ de tantale, le dit alliage comprenant des additifs de contrôle des grains uniformément distribués à l'intérieur, les dits additifs consistant entre 30 et 200 parts par million de potassium et moins de 100 parts par million de silicium.
16. Une lampe à incandescence selon la revendication 15 caractérisée en ce que le dit composant présente une structure en grains fins résistant aux vibrations, la dite structure en grains étant stable jusqu'à une température supérieure à au moins 2200°C.
17. Une lampe à incandescence selon la revendication 16 caractérisée en ce que les dites entrées de courant font partie du dit composant.
18. Une lampe à incandescence selon la revendication 17 caractérisée en ce que le dit filament fait partie du dit composant.
19. Une lampe à incandescence selon la revendication 17 caractérisée en ce que la dite lampe est une lampe à halogène.
20. Une lampe à incandescence selon la revendication 15 caractérisée en ce que la dite lampe est une lampe à halogène.
21. Une lampe à incandescence selon la revendication 20 caractérisée en ce que le dit filament fait partie du dit composant et présente une structure en grains résistant à la pliure comprenant des grains importants s'étendant dans le sens longitudinal du fil.
22. Une lampe à incandescence selon la revendication 21 caractérisée en ce que la dite structure en grains résistant à la pliure est obtenue par recristallisation d'une structure en grains fins à une température supérieure à 2500°C environ.
23. Une lampe à incandescence selon la revendication 22 caractérisée en ce que le dit filament affecte la forme d'une bobine bobinée.
24. Une lampe à incandescence selon la revendication 20 caractérisée en ce que la dite lampe comprend un moyen formant getter et faisant partie du dit composant.
25. Une lampe à incandescence selon la revendication 24 caractérisée en ce qu'au moins l'une des entrées de courant comporte le dit moyen formant getter.
26. Une lampe à incandescence selon la revendication 24 caractérisée en ce qu'un support de filament est inclus dans le dit moyen formant getter.
27. Procédé pour réaliser un fil en alliage tungstène-tantale caractérisé en ce qu'il comporte les étapes suivantes:
- mélange d'une poudre de tungstène substantiellement pure, dopée au moyen d'additifs de contrôle des grains comprenant du potassium et du silicium et une poudre de tantale substantiellement pure,
-compactage de la poudre pour former un lingot,
frittage du lingot sous hydrogène ou sous vide pendant un temps suffisant pour former une solution en phase solide de tungstène et de tantale, et
- transformation mécanique du lingot résultant en un fil en alliage.
28. Procédé pour réaliser un fil en alliage de tungstène et de tantale selon la revendication 27 caractérisé en ce que l'on mélange suffisamment de poudre de tantale pour obtenir un fil en alliage consistant essentiellent de tungstène et entre 0,2 et 6% en poids de tantale.
EP82901088A 1981-03-09 1982-03-01 Fil en alliage pour composants de lampes et lampes le comprenant Expired EP0073814B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US24195981A 1981-03-09 1981-03-09
US241959 1981-03-09

Publications (3)

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EP0073814A1 EP0073814A1 (fr) 1983-03-16
EP0073814A4 EP0073814A4 (fr) 1983-07-04
EP0073814B1 true EP0073814B1 (fr) 1986-01-08

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EP82901088A Expired EP0073814B1 (fr) 1981-03-09 1982-03-01 Fil en alliage pour composants de lampes et lampes le comprenant

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EP (1) EP0073814B1 (fr)
JP (1) JPS58500328A (fr)
CA (1) CA1184967A (fr)
DE (1) DE3268352D1 (fr)
WO (1) WO1982003138A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5148080A (en) * 1990-01-16 1992-09-15 Hilux Development Incandescent lamp filament incorporating hafnium

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1508241A (en) * 1917-02-20 1924-09-09 Gen Electric Metal and its manufacture
US1602526A (en) * 1922-09-15 1926-10-12 Westinghouse Lamp Co Control of crystal development in refractory metals
US3236699A (en) * 1963-05-09 1966-02-22 Gen Electric Tungsten-rhenium alloys
US3748519A (en) * 1971-10-06 1973-07-24 Westinghouse Electric Corp Tubular heat lamp having integral gettering means

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1854970A (en) * 1930-05-20 1932-04-19 Gen Electric Electric lamp and the illuminating body used therein
US2225239A (en) * 1936-08-14 1940-12-17 Spaeth Charles Filament
US3069584A (en) * 1959-07-29 1962-12-18 Jack W Frazer Method of making tungsten filaments
US3210589A (en) * 1960-04-28 1965-10-05 Westinghouse Electric Corp Electric incandescent lamp having filament of partially recrystallized fibrous structure
US3346761A (en) * 1965-07-02 1967-10-10 Gen Electric Incandescent lamp with a tungsten filament with tantalum imbedded in the surface to act as a gettering agent
US4020383A (en) * 1975-12-31 1977-04-26 Gte Sylvania Incorporated Method of pulsing incandescent lamp filaments
US4296352A (en) * 1979-12-19 1981-10-20 General Electric Company Incandescent lamp

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1508241A (en) * 1917-02-20 1924-09-09 Gen Electric Metal and its manufacture
US1602526A (en) * 1922-09-15 1926-10-12 Westinghouse Lamp Co Control of crystal development in refractory metals
US3236699A (en) * 1963-05-09 1966-02-22 Gen Electric Tungsten-rhenium alloys
US3748519A (en) * 1971-10-06 1973-07-24 Westinghouse Electric Corp Tubular heat lamp having integral gettering means

Also Published As

Publication number Publication date
EP0073814A4 (fr) 1983-07-04
CA1184967A (fr) 1985-04-02
EP0073814A1 (fr) 1983-03-16
JPS58500328A (ja) 1983-03-03
WO1982003138A1 (fr) 1982-09-16
DE3268352D1 (en) 1986-02-20

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