WO2007063008A2 - Lampe a incandescence halogene comportant un corps luminescent contenant du carbure - Google Patents

Lampe a incandescence halogene comportant un corps luminescent contenant du carbure Download PDF

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Publication number
WO2007063008A2
WO2007063008A2 PCT/EP2006/068738 EP2006068738W WO2007063008A2 WO 2007063008 A2 WO2007063008 A2 WO 2007063008A2 EP 2006068738 W EP2006068738 W EP 2006068738W WO 2007063008 A2 WO2007063008 A2 WO 2007063008A2
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WO
WIPO (PCT)
Prior art keywords
filament
incandescent lamp
metal
carbon
luminous body
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.)
Ceased
Application number
PCT/EP2006/068738
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German (de)
English (en)
Other versions
WO2007063008A3 (fr
Inventor
Axel Bunk
Matthias Damm
Georg Rosenbauer
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 GmbH
Original Assignee
Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
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 Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH filed Critical Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
Publication of WO2007063008A2 publication Critical patent/WO2007063008A2/fr
Publication of WO2007063008A3 publication Critical patent/WO2007063008A3/fr
Anticipated expiration legal-status Critical
Ceased 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
    • H01K1/10—Bodies of metal or carbon combined with other substance
    • 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

Definitions

  • the invention relates to a halogen incandescent lamp with carbide-containing luminous body according to the preamble of claim 1. Such lamps are suited for general lighting ⁇ and used for photo-optical purposes.
  • Incandescent and incandescent halogen lamps have the advantage over discharge lamps that they contain no highly toxic substances such as mercury and can be switched quickly. In contrast to discharge lamps and LEDs, they can do without complex ballasts.
  • the main disadvantage of halogen incandescent lamps or incandescent lamps is their lower efficiency compared to LEDs and discharge lamps.
  • incandescent bodies of refractory ceramics such as tantalum carbide. See, for example, Becker, Ewest: “The Physical and Radiation Properties of Tantalum Carbide", Journal of Technical Physics, No. 5, pp. 148-150 and No. 6, pp. 216-220 (1930))
  • Increasing Efficiency arises from the fact that the filament of metal tallcarbid because of the comparison with the pure metals, much higher melting point at a higher temperature Betrie ⁇ can ben: melting point of TaC is 388O 0 C against ⁇ about 341O 0 C for tungsten.
  • the emission coefficient of the carbides in the visible Be ⁇ rich greater than in the infrared spectral range compared with tungsten the emission coefficient of the carbides in the visible Be ⁇ rich greater than in the infrared spectral range.
  • tantalum carbide is a better "selective radiator" than tungsten.
  • a problem with the operation of tantalum carbide lamps at high temperatures is the decarburization; This leads to the formation of subcarbides with a higher specific resistance and a lower melting point and thus to the rapid destruction of the luminous body.
  • a particular problem here is that the carbon vapor pressure over the tantalum carbide is relatively large. Operating temperature at the same loading ⁇ the evaporation rate in g cm "2 s" 1 of the carbon on tantalum carbide by more than a large ⁇ jackowskiowski greater than that of tungsten on a tungsten surface. For details regarding the vapor ⁇ fung speeds of various refractory carbides see L.
  • the rapid decarburization of a Tantalkar ⁇ bid - to prevent filament is to operate it in an externally so strong angereicher- th with carbon atmosphere that a depletion of the luminous body at carbon is avoided.
  • the luminous body is operated in an atmosphere in which the carbon vapor pressure corresponds approximately to the equilibrium vapor pressure of the carbon over the tantalum carbide. This is achieved by permanently transporting carbon from a source to a sink.
  • the object of the present invention is to increase the lifetime of a generic lamp and to reduce the bulb blackening.
  • the invention is based on the idea of making changes to the base material in such a way that the melting point is increased and the vapor pressure is lowered. In any case, these measures have the effect of increasing the service life or reducing the density of the piston. It has been shown that the melting point of the carbides TaC, HfC and ZrC increases when this material easy to coals ⁇ be impoverished and thus stoichiometric carbides. For example, while the melting point of the nearly stoichiometric tantalum carbide TaC 0 , 98 is in the range between 383O 0 C and 388O 0 C, the melting point of TaC 0 , 8 at about 4000 0 C is determined.
  • Analog can be found for the melting point of the near stoichiometric HFCO, 97 a range of 3700 0 C - 376O 0 C, while the melting point of HfC 0, 9 is determined to 382O 0 C.
  • An increase in the melting point ⁇ is also connected to a lowering of the carbon material ⁇ vapor pressure.
  • Metallic carbide filaments are usually produced by carburization of the respective metals, cf.
  • G. Hörz "carburizing and decarburization of niobium and tantalum", metal 27, Issue 7 (July 1973), pages 680-687.
  • Herge ⁇ can be made lamps with luminous bodies of stoichiometric metal carbides eg by incomplete carburization
  • care must be taken to ensure that the carbon content in the respective lamps is balanced by homogenization at a lower temperature before use at full operating temperature, otherwise the wire on the outside may possibly be present when using wires even with coal fabric supersaturated metal carbide, while in the middle of the wire still a "soul" from the lower melting subcarbide Ta 2 C or even more areas of the phases of Ta 2 C or Ta are, see, for example, Okoli, R. Haubner, B. Lux, "Carburization of tungsten and tantalum filaments during low pressure diamond deposition", Surface and Coatings Technology, Al_ (1991), 585-599.
  • the homogenization is preferably carried out at temperatures at which on the one hand the carbon evaporation no On the other hand, however, the rate of diffusion of carbon in TaC or Ta 2 C or Ta is already sufficiently high.
  • the surface of the filament by chemical Abtragspro ⁇ processes to "smooth out". Therefore, it is advantageous for the generation ⁇ supply of light fittings of metal carbides with a un- terstöchiometrischen content of carbon the Leuchtkör- During decarburization, concentration differences are built up, ie the luminous element (eg the filament) depletes of carbon on the outside Before homogenizing the luminous body, it should therefore be homogenised, ie by diffusion of the carbon from the inside to the outside to concentration differences compensated ⁇ the.
  • This homogenization should preferably temperatures at tempera ⁇ be made from 2300 K and 3000 K, that is at temperatures at which the evaporation of tantalum and carbon yet sufficiently slow, on the other hand the diffusion of carbon is already sufficiently fast (goal: the shortest possible process time).
  • the temperature should preferably be in such a temperature range as that
  • An example of such a chemical reaction system is the system tantalum-carbide-oxygen.
  • the oxygen acts strongly decarburating on the metal carbide, for example: 2 TaC + 1 / 2O 2 -> Ta 2 C + CO
  • the concentration of the decarburization agent should preferably be chosen so small that the rate of decarburization alone by the number of atoms per unit time occurring on the surface atoms or molecules of this substance, for example, oxygen atoms, possibly from the Zer ⁇ case of a precursor have arisen - is determined.
  • a layer of tantalum is formed on the outside of the luminous element, which in turn envelops layers of tantalum subcarbides, which in turn comprise the tantalum carbide ,
  • a luminous wire then consists of a tantalum carbide core, which is covered by a tantalum subcarbide shell (or possibly two phases of tantalum subcarbide). The tantalum subcarbide is surrounded by a shell of tantalum.
  • the boundary conditions should preferably during the decarburization be adjusted so that the determined for all Stel ⁇ len almost the same partial pressure of the oxygen atoms at the surface of the luminous body, the rate of decarburization. That is, the degree of decarburization should be determined by the product Zpt, which is only comparatively slightly dependent on the temperature (Z: burst number, p: partial pressure of the oxygen or of the substance causing the decarburization, t: time).
  • the rate of decarburization doubles when the partial pressure of the oxygen or the oxygen-containing substance is doubled. It must be ensured that the sauerstoffhalti ⁇ ge precursor, is when it encounters the luminous body, already disintegrated over wide temperature ranges, because their case again the precursor leads to ⁇ the kinetics of decay to the hotter unavoidable preferred decarburization points.
  • the procedure for incomplete carburizing is preferably designed so that
  • the reaction time of the gas mixture used for the carburization is shortened compared with the complete carburization so that the degree of carburization in the tantalum carbide is within the stated target range.
  • the carbon content in the gas used for carburization (advantageously CH 4 / H 2 mixture, but possible also other hydrocarbon - hydrogen - inert gas mixtures) is reduced.
  • the temperature of the wire to be carburized is lowered, (advantageously from typically 2900 K - 3100 K to about 2600 K - 2800 K).
  • the lowering of the luminous body temperature can take place on the one hand via a lower power input but also with the same power supply via an increased heat dissipation via the carbonization gas.
  • the increased hydrogen content in the metal carbide (eg tantalum carbide) resulting from incomplete carburization can lead to an increased release of hydrogen during lamp operation.
  • This hydrogen emission in the operation of lamps leads to a reduction of the blackening and to an increase of the service life in lamp operation.
  • the carbon which evaporates from the luminous body reacts by means of the hydrogen dissolved out at higher temperatures near the piston wall to give hydrocarbons (in particular methane ), which is then split again at relatively high temperatures and thus forms the carbon-hydrogen cyclic process already mentioned.
  • Incomplete carburization also has a positive effect on increasing the pressure of the hydrogen-rich carburizing medium (from approx. Typically 1 mbar to approx. 1000 mbar).
  • Due to the higher thermal conductivity - due to the higher pressure - in the hydrogen-rich carburising gas (for example, CH 4 / H 2 mixture) is a higher glass ⁇ temperature in the carburized lamp in front, which is preferably of favoring the hydrogen diffusion into the existing lamp bulb ( made of quartz glass) leads.
  • the hydrogen from the filling gas necessary for the CH cyclic process becomes too fast in the quartz glass later during lamp operation. is sorbed.
  • the glass and the metalli ⁇ rule components may also be welded catalysts such as described in DE 10 2004 059 174 1) due the higher hydrogen partial pressure also dissolve more hydrogen or bind as Me ⁇ tallhydrid.
  • These highly hydrogen-loaded metals then absorb less hydrogen during lamp operation or possibly even release hydrogen and thus contribute to stabilizing or slightly increasing the hydrogen content during lamp operation and thus delaying or preventing the onset of bulb blackening.
  • the hydrogen partial pressure during carburization is closer to the later hydrogen partial pressure in the closed lamp during lamp operation.
  • sulfur can also be used for decarburization, for example in the form of hydrogen sulphide H 2 S, carbon disulfide CS 2 or else mercaptans.
  • H 2 S hydrogen sulphide
  • CS 2 carbon disulfide
  • mercaptans mercaptans
  • H 2 S -> S + H 2 2 TaC + S -> Ta 2 C + CS A decomposition of CS only occurs at temperatures significantly above 3000 K. Again, there is no Reakti ⁇ on tantalum sulfides, at least at the considered high temperatures in the luminous body above 2200K. Tantalum sulfides are formed on the colder spiral outlets.
  • Analog can in principle also use hydrogen to Ent ⁇ carbonisation. Hydrogen significantly react with carbon to form gaseous hydrocarbons at temperatures below 1000 K, ie at temperatures at which the reaction stops at the surface because the carbon speed can not be supplied from the inside because of the much too low Diffusionsge ⁇ .
  • a brief transient heating of the filament at temperatures ranging from 2400 K to 3000 K the carbon is again Diffu ⁇ sion from the interior to the surface allows. After that, decarburization then takes place again at a lower temperature. That is, by alternately operating the filament at low temperatures well below 1000 K and higher temperatures in the range between 2400 K and 3000 K alternately decarburization on the surface of the filament and a subsequent delivery of carbon from the inside are performed.
  • the degree of decarburization can be determined in a simple and destructive manner , for example by measuring the specific electrical resistance of partially decarburized coils in comparison to fully carburized coils, cf. eg JRCooper and RL Hansler, "Variation of Electrical Resistivity of cu bic tantalum carbide with composition", Journal of Chemical Physics 3_9, 248-249 (1963) or G. Santoro, "Varia ⁇ tion of Some Properties of Tantalum Carbide with Carbon Content ", TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME, vol. 227, 1361-1368 (1963).
  • the use of more complex methods - eg spectroscopic methods - possibly after chemical reactions - is also possible, cf. eg the most recently cited reference or the abovementioned article by Hörz.
  • FIG 1 shows an incandescent lamp with carbide filament according to an embodiment.
  • FIG. 1 shows an incandescent lamp 1 with a bulb of quartz glass 2, a pinch 3, and internal power supply lines 6, the foils 4 in the pinch seal 3 connect with a luminous element 7.
  • the luminous element is a simply wound, axially arranged wire made of TaC, whose uncoiled ends 14 are continued transversely to the lamp axis.
  • the outer leads 5 are attached to the outside of the foils 4.
  • the inner diameter of the piston is 5 mm.
  • the coil ends 14 are then bent parallel to the lamp axis and form the inner power supply lines 6 as an integral extension.
  • the current supply lines 6 are provided with a coating coil or with a coating 8, for example of carbon, rhenium, osmium or tantalum boride, over at least part of their entire length, in order to increase the mechanical stability at the pinch edge.
  • tantalum carbide filament lamp which consists of tantalum carbide filament lamp schematically shown in Figure 1, the basic design largely corresponds to a low-voltage halogen incandescent lamp available on the market, by Carburie- tion of a tantalum wire (diameter 125 micrometers) threaded ⁇ oped helical (6 turns) emerged.
  • the TaC filament was heated in the stud lamp by applying an external voltage to about 3000 K.
  • an inert gas such as krypton in the pressure range between 10 mbar and 30 mbar and an addition of N 2 O in the concentration range between 50 ppm and 200 ppm is selected.
  • the lamp has a power consumption of approx. 13 V when operated at approx. W, wherein the color temperature is characteristic ⁇ around 3500 K.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Resistance Heating (AREA)

Abstract

L'invention concerne une lampe à incandescence halogène comportant un corps luminescent contenant du carbure et des conduites d'alimentation électrique maintenant le corps luminescent. Un corps luminescent et une charge sont introduits ensemble de façon étanche au vide dans un piston, le corps luminescent présentant un carbure métallique dont le point de fusion est supérieur à celui du tungstène, la teneur en carbone du carbure métallique étant inférieure à celle obtenue après carburation complète, une carburation complète se traduisant par la formation de carbures métalliques dont le nombre d'atomes de métal et d'atomes de carbone se trouvent en relation stoechiométrique entière l'un par rapport à l'autre.
PCT/EP2006/068738 2005-11-30 2006-11-22 Lampe a incandescence halogene comportant un corps luminescent contenant du carbure Ceased WO2007063008A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102005057084.4 2005-11-30
DE200510057084 DE102005057084A1 (de) 2005-11-30 2005-11-30 Halogenglühlampe mit carbidhaltigem Leuchtkörper

Publications (2)

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WO2007063008A2 true WO2007063008A2 (fr) 2007-06-07
WO2007063008A3 WO2007063008A3 (fr) 2007-10-11

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7722421B2 (en) 2006-03-31 2010-05-25 General Electric Company High temperature ceramic composite for selective emission
US7851985B2 (en) 2006-03-31 2010-12-14 General Electric Company Article incorporating a high temperature ceramic composite for selective emission
US8044567B2 (en) 2006-03-31 2011-10-25 General Electric Company Light source incorporating a high temperature ceramic composite and gas phase for selective emission

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3113893A (en) * 1960-10-14 1963-12-10 Sylvania Electric Prod Incandescent filament
ES281314A1 (es) * 1961-11-29 1963-03-16 Lampes Sa Mejoras introducidas en la fabricación de lámparas incandescentes
BE625922A (fr) * 1961-12-13
NL6513874A (fr) * 1965-10-27 1967-04-28
US3441777A (en) * 1966-06-01 1969-04-29 Gen Telephone & Elect Elements for incandescent devices
US3523207A (en) * 1968-01-18 1970-08-04 Westinghouse Electric Corp Incandescent lamp with tantalum carbide filament and nitrogen gas atmosphere
DE10358262A1 (de) * 2003-12-01 2005-09-01 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Glühlampe mit Kohlenstoff-Kreisprozess

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7722421B2 (en) 2006-03-31 2010-05-25 General Electric Company High temperature ceramic composite for selective emission
US7851985B2 (en) 2006-03-31 2010-12-14 General Electric Company Article incorporating a high temperature ceramic composite for selective emission
US8044567B2 (en) 2006-03-31 2011-10-25 General Electric Company Light source incorporating a high temperature ceramic composite and gas phase for selective emission

Also Published As

Publication number Publication date
WO2007063008A3 (fr) 2007-10-11
DE102005057084A1 (de) 2007-05-31

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