EP1805785A2

EP1805785A2 - Incandescent lamp having an illuminant that contains a high-temperature resistant metal compound

Info

Publication number: EP1805785A2
Application number: EP05803936A
Authority: EP
Inventors: Axel Bunk; Matthias Damm; Georg Rosenbauer
Original assignee: Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
Current assignee: Osram GmbH
Priority date: 2004-10-26
Filing date: 2005-10-18
Publication date: 2007-07-11
Anticipated expiration: 2025-10-18
Also published as: DE102004052044A1; WO2006045273A2; US20090045742A1; WO2006045273A3; CN101048850A; EP1805785B1; CN101048850B; ATE490547T1; JP4571981B2; CA2584458A1; DE502005010636D1; US7911121B2; JP2008518409A

Abstract

The invention relates to an incandescent lamp (1) which is provided with an illuminant (7) which is inserted in a bulb (2) together with a filling in a vacuum-tight manner, the illuminant (7) comprising a metal carbide that has a melting point above that of tungsten. The bulb also comprises a source and a sink for a material of which the illuminant is depleted during use.

Description

Incandescent lamp with a luminous body, which contains a hochtempera¬ turbeständige metal compound

Technical area

The invention is based on an incandescent lamp with a luminous body which contains a highly temperature-resistant metal compound, according to the preamble of claim 1. These are, in particular, incandescent lamps with a carbide-containing luminous body, in particular the invention relates to halogen incandescent lamps which are ei - Have a luminous body of TaC, or the luminous body contains TaC as Bestand¬ part or coating.

State of the art

Many writings disclose an incandescent lamp with a luminous element which contains a highly temperature-resistant metal compound. A hitherto unsolved problem is the severely limited lifetime. A possibility presented in WO-A 01/15206 is to connect the luminous element with a separate frame for mounting.

A common method of solving the problem of preventing vaporization of filament material is by using circular processes. In this case, the filling gas, a further chemical substance is added, which reacts in colder areas with the evaporated material to a relatively volatile compound, which does not deposit on the bulb wall. This compound is transported in the direction of the concentration gradient, namely high concentration near the bulb wall, low concentration near the filament, in the direction of the luminous body. At the high temperatures near the filament it decomposes with decomposition into the material of the filament and zu¬ given chemical substance; the material of the filament is again attached to this. Examples:

(a) Tungsten-halogen cycle process

The evaporating from the tungsten filament connects at lower temperatures near the bulb wall to form tungsten halides which are volatile at temperatures above about 200 ⁰ C and is not deposited on the benwand Kol¬. As a result, a failure of tungsten on the piston wall is prevented. The tungsten halide compounds are transported back by diffusion and possibly also convection to the hot filament, where they decompose. The freed tungsten is again attached to the filament. However, the tungsten i.allg. not transported back to the same place from which it has evaporated but deposited at a location of different temperature, ie the cycle is not regenerative. An exception is the fluorine cycle.

(b) Carbon-hydrogen cycle in TaC lamps

The gaseous carbon formed upon decomposition of the TaC is transported in the direction of the piston wall, where it reacts with hydrogen to form hydrocarbons such as methane. These hydrocarbons are transported back to the hot filament, where they decompose again. The carbon is released again and can attach to the filament. However, the hydrocarbons already decompose below 1000 K at low temperatures, so that the recycling of carbon does not take place in a targeted manner to the hottest points of the luminous element.

If, as in the last-described example, the evaporation from the luminous body is relatively strong and the compound carrying the cyclic process is stable only at very low temperatures, such as the hydrocarbons in the last example, the luminous body will be rapidly destroyed, because it will rapidly adhere to the evaporating material such as carbon in the last example depleted. Overall, the carbon is relatively quickly from the hei¬ ßesten points of the filament to the colder places of the filament or the outlets transported to the luminous body, which can also cause problems, for example by Windungsschluss. Only a very small proportion of the transported back carbon reaches the hottest point of the helix (very low degree of regeneration). In addition, the back reaction of the carbon with the hydrogen to hydrocarbons proceeds in any case only with a relatively large excess of hydrogen sufficiently fast, so that a blackening of the piston is avoided.

In summary, in such cases as in the case of the TaC lamp, the use of a cyclic process in which:

(a) first of all, the material evaporates or is transported off the filament relatively quickly, and

(B) secondly, the evaporated material enters into a chemical compound only at very low temperatures, not sufficient for many applications, because because of the only very low return of material to the points from which it was removed, the filament is destroyed quickly.

As a way of solving the problem, WO-A 03/075315 describes the generation of the luminous element from a depot. From the depot continuously evaporates a chemical substance, which supplies the luminous body that substance to which it is depleted again. For example, it describes how a TaC luminous body is regenerated from a polymer impregnated with an organic compound (eg acetone). In the process, the gas phase is permanently supplied with a chemical compound, which also contains carbon. In this case, carbon is provided continuously, which can replace the evaporated by the filament carbon again. The disadvantage here is that the composition of the gas phase and also of the luminous element changes continuously due to the permanently supplied chemical compound; a lamp operation under stable conditions is hardly possible. The concentration of carbon in the gas phase is constantly increased, which eventually leads to the deposition of carbon in inappropriate places such as the ends of the luminous body or finally the bulb wall. An enrichment of carbon in the luminous body is not desirable because it changes the properties of the filament continuously. An enrichment of hydrogen in the gas phase leads by increasing the heat conduction to an increasing cooling of the filament.

In summary, stable operation of a lamp with a chemical compound continuously evaporating from a depot is not possible, because the composition of the gas phase and possibly also of the luminous element itself changes continuously.

Another possibility is described in WO Patent 03/075315 the mutual Re¬ generation of two alternately operated luminous body. In this case, carbon continuously evaporates from an "active" filament operated at high temperatures (above 3000 K) and is transported to a second "inactive" filament operated at relatively low temperatures (around or below 2000 K), where it is separates or attaches. If the "active" luminous body is depleted of carbon, it is switched over, the previously "inactive" filament is operated at high temperature, and the previously "active" filament is kept at a low temperature, thereby becoming the now "inactive" filament Regenerated by the "active" carbon-evaporating filament, which is disadvantageous in that two luminous bodies are required, between which it is necessary to constantly switch over.

Presentation of the invention

It is an object of the present invention, an incandescent lamp with a luminous body, which contains a high-temperature-resistant metal compound, and in particular a carbide-containing luminous body, or a metal, according to the preamble of

Claim 1, which allows a long service life and the sample The impoverishment of the filament on a evaporating component is overcome.

These objects are achieved by the characterizing features of claim 1. Particularly advantageous embodiments can be found in the dependent claims.

The term high temperature resistant metal compound means compounds whose melting point is near the melting point of tungsten, sometimes even higher. The material of the luminous body is preferably TaC or Ta ₂ C. However, carbides of Hf, Nb or Zr and, moreover, alloys of these carbides are suitable. Further, nitrides or borides of such metals. Common to these compounds is the property that a luminous body made of this material becomes depleted in operation on at least one element. However, the principle described below is equally applicable to filaments of metals. The term metal compound used below is therefore not to be understood as limiting, but by way of example. The statements made therein are analogously applicable to metals.

If a luminous element is operated at high temperatures, depending on the nature of the material of the luminous element, the material or components of the material evaporate. The evaporated material or its constituents are replaced by e.g. Convection, diffusion or thermal diffusion removed and deposit elsewhere in the lamp, e.g. on the piston wall or frame parts. As a result of the evaporation of the material or its constituents, the light-emitting body is destroyed. Due to the material which separates on the bulb wall, the transmission of the light is greatly reduced.

Examples:

(a) The tungsten evaporating from a tungsten filament is transported to the bulb wall in a conventional incandescent lamp and deposits there. (b) A tantalum carbide luminous body operated at high temperatures decomposes to form the brittle subcarbide Ta ₂ C which melts at lower temperatures relative to TaC and of gaseous carbon which is transported to the bulb wall and separates there.

The task consists in minimizing or reversing evaporation by means of suitable measures.

In order to avoid a depletion of the filament on the evaporating component, such a concentration of the evaporating component is adjusted from the outside that in the ideal case evaporation and sublimation keep the equilibrium and the filament is thus neither depleted nor enriched in the component in question. The adjustment of the required concentration over the luminous element is to be realized by a continuous transport of a substance containing the component in question from a source into a sink. Due to the continuous deposition of the material supplied from the source, a change in the composition of the gas phase is avoided and an operation of the luminous element under constant conditions is made possible.

In one possible design form of a lamp with TaC filament be¬ the source of a solid, or liquid, hydrocarbon, which is introduced into the lamp so that above the source Mate¬ rial builds up a certain vapor pressure of gaseous hydrocarbon. This hydrocarbon is transported by diffusion or convection into the inside of the lamella, where it decomposes near the luminescent body at higher temperatures. The luminous body is thus in a carbon-enriched atmosphere; a decomposition of the filament is thereby prevented. Ideally, the luminous body does not emit carbon to the environment, nor is carbon enriched in it. In other words, the luminous body has an equilibrium between carbon deposition and carbon evaporation. At lower temperatures near the bulb wall, the carbon reacts again Back to hydrogen hydrocarbons. At a wire attached at a suitable temperature, for example from one of the materials iron, nickel, cobalt, platinum or molybdenum of sufficiently large surface area, the hydrocarbon decomposes with the deposition of solid carbon (soot). This process corresponds approximately to the cracking of hydrocarbons known from industrial chemistry on suitable catalysts, in which case the deposition of carbon on the catalyst is desired, in contrast to the reaction regime in plants of the chemical industry. Overall, therefore, carbon continuously exits from one source and is re-deposited in a sink. The filament of the lamp is thus neither enriched in carbon, nor depleted of carbon; In addition, the carbon concentration in the gas phase is kept constant.

The hydrogen can preferably be used analogously. As a hydrogen sink, the permeable quartz piston wall acts at high temperatures. At lower temperatures, the resulting hydrogen can be trapped by iodine (reaction to hydrogen iodide); The resulting hydrogen iodide is not critical in terms of its effect on the maintenance of the lamp, because it does not interfere with the chemistry of the metal carbide nor changes the physical properties of the filling gas (in particular the thermal conductivity). Another way of attaching the released hydrogen (i.e., a sink to hydrogen) is to use metals such as e.g. Zirconium or hafnium or niobium or tantalum, which "getter" hydrogen at suitable temperatures.

It should be pointed out again that the existence of a sink is important to the functionality of the lamp. In the absence of sinks for carbon and hydrogen, either the gas phase or the luminous body would accumulate on the respective element; the result would be a change in the operating data of the lamp.

In particular, the transport processes described in the last paragraphs can still be superimposed by one or more cycle processes. If, for example, carbon in a lamp with a luminous body of TaC is constantly transported from a source to a sink, in some cases in the form of hydrocarbons, then a tantalum-halogen cyclic process can be superimposed on this transport process by adding a halogen-containing compound which prevents the tantalum evaporated by the luminous body from depositing on the bulb wall and at least partially transports it back to the luminous body, as described, for example, in the still unpublished application DE-A-103 56 651.1. These are expressly referred to. Furthermore, it is conceivable for a TaC lamp to superimpose a carbon cycle process on the described permanent transport of carbon from a source into a sink, for example a CH, C-halogen, CS or CN cycle process as in the application DE-Az 103 56 651.1 described be¬.

The sinking metals may be e.g. in the form of wires or plates welded to the frame or the power supply, or wound as a coating coil directly around the power supply, or e.g. in the form of wires to be squeezed directly. Particularly when using catalytically active metals as sinks, it is essential that the surface of these metals be sufficiently large, since the surface is continuously covered with carbon ("poisoning" of the catalyst) in order to obtain the effectiveness of the catalyst the coating of helical outlets or power supply lines with metals serving as drain is a further embodiment.

In another embodiment, elemental carbon is used as the source of carbon. This can be present, for example, in the form of carbon pressings, graphite fibers or carbon black deposited on a substrate, diamine in the form of DLC or graphite. The carbon is held at a "middle" temperature, which must be just so high that the resulting vapor pressure of the carbon at the location of the hot luminous body leads to a carbon partial pressure which is approximately equal to the carbon Equilibrium vapor pressure over the tantalum carbide corresponds. Thus keep the luminous body of tantalum carbide carbon deposition and carbon evaporation equilibrium; a Dekarburierung the filament is avoided. If the carbon reaches the piston wall in colder regions, it reacts with hydrogen or else with halogens to form (optionally halogenated) hydrocarbons; This prevents the deposition of the carbon on the piston wall. The decomposition of the hydrocarbon then takes place on a catalyst, in which case the carbon deposits on the surface of the catalyst and the hydrogen is liberated again. In this case, there is no need for a sink for the hydrogen or, if appropriate, the halogen, which in fact only prevent the deposition of the carbon on the piston wall and transport the carbon bound in the form of hydrocarbon to the catalyst. The hydrogen or optionally the halogen thus serves only as a means of transport to transport the carbon and is not consumed. Overall, in this case, carbon is transported from the carbon source (carbon compact, graphite fibers, diamond such as DLC, graphite layers, carbon black, etc.) to the carbon sink (for example wire made of nickel, iron, molybdenum), where it settles which separates.

In one embodiment of the carbon source, the carbon is deposited on single turns of the metal carbide filament designed as a helix. Preferably, the carbon deposition takes place on the outer turns of the coil at lower temperatures than in the middle of the filament. Since the vapor pressure over pure carbon is greater than the carbon vapor pressure over tantalum carbide, the source of pure carbon is attached at lower temperatures than in the hot helical center. This is intended to set the carbon equilibrium vapor pressure above the middle of the hot filament as far as possible and to ensure that no gradient of the carbon partial pressure driving the carbon transport is produced via the filament. The last-mentioned procedure is also of use for circumventing problems with regard to the relatively low impact strength of the tantalum carbide during transport of the lamps to the customer. One option for circumventing this problem is to complete the carburization only after the lamps have been transported to the customer during the firing process, and initially to leave at least one tantalum core in the luminous body made of TaC. In order to then complete the carburization at the customer, it is necessary to supply large amounts of carbon to the incompletely fully carburized luminous body when the lamp is burnt in. If one stores these large amounts of carbon in the form of gaseous hydrocarbons in the gas atmosphere or in the form of continuously evaporating solid hydrocarbons, then very large amounts of hydrogen are liberated in the carburization reaction, which then have a negative effect on efficiency because of the increase in thermal conductivity affect the lamp. Since the reaction with the hydrocarbon also does not proceed completely, the large amounts of released carbon which must be supported in the gas phase also present a problem. This problem can be circumvented in the manner described by not yet fully permitting - Carburized luminescent body is in a continuous stream of carbon emanating from a carbon source of electricity. The carbon, which is not related to carburization, reacts with hydrogen to form hydrocarbons, whereby the deposition of the carbon on the piston wall is prevented. The hydrocarbon eventually decomposes back to a catalyst, depositing the unneeded carbon and liberating the hydrogen. It comes with a relatively small amount of hydrogen, because it is not consumed, but only serves to transport the carbon to the carbon sink. In particular, the amount of hydrogen remains constant and does not permanently increase during carburization. If the permeability of the hydrogen is no longer negligible at high piston temperatures, in particular in the case of a quartz glass flask, the hydrogen can be replaced by the hydrogen Use of iodine near the bulb wall again as iodine hydrogen ab¬ catch and stabilized.

Another way to realize a carbon source is to use a tantalum carbide coated carbon fiber. At the high operating temperatures, the carbon diffuses through the tantalum carbide layer; a depletion of the tantalum carbide layer of carbon is thus avoided. However, the carbon released thereby into the gas space leads to a rapid blackening of the piston wall if no countermeasures are taken. By trapping the carbon with hydrogen, blackening of the bulb can be prevented if the bulb temperatures are not too high. However, very large amounts of hydrogen are needed to "trap" the carbon as completely as possible before it is deposited on the bulb wall, which can be avoided by holding the hydrocarbon at a catalyst maintained at a suitable temperature, eg a nickel wire. Iron, etc. In this process, the carbon deposits on the nickel wire, while the hydrogen is released again and is available for reaction with further carbon, so that the hydrogen merely serves as a "vehicle" for transporting carbon from the luminous body by formation Catch of hydrocarbon and to carbon sink (eg wire nickel, molybdenum, ...) to transport. Overall, no hydrogen is consumed in this transport mechanism, ie it is possible with a relatively small amount of hydrogen. If an alternative cyclic process were to be implemented, it would be necessary to use very large amounts of hydrogen in order to trap the carbon transported in large concentrations by the luminous body by forming hydrocarbons or to build up such a high concentration of hydrocarbons near the piston wall. that the return transport of carbon to Leucht¬ body exactly compensates for the removal. Using such large amounts of hydrogen would greatly reduce the efficiency of the lamp. AIs further possibility of the design of a source, it is advisable to coat the filament with the material to which it is depleted and which is to be fed back from a source, and then again a layer of the actual filament material from the outside on this layer applied. If a luminous element eg consists of a metal carbide such as tantalum carbide or hafnium carbide, a layer of carbon is deposited on the surface of the filament of metal carbide. On this layer of carbon, a layer of a metal carbide is then applied again. If carbon from the outer metal carbide layer evaporates during lamp operation, then carbon immediately diffuses from the inside of the enclosed carbon layer and prevents the outer metal carbide layer from becoming poor in carbon. In this regard, the functioning of those of a metal carbide-coated carbon fiber is quite similar. In this procedure, however, it is advantageous that in the manufacture of the luminous element, it is possible to make extensive use of process technology established in halogen lamp construction. The application of the carbon coating takes place, for example, according to a CVD method in the column lamp, for example by decomposition of Me¬ than (1 bar pressure) at a temperature of about 2,500 K on the luminous body. The deposition of the metal carbide outer layer is carried out in the CVD process, for example, by simultaneous thermal decomposition of metal halides such as tantalum halide and methane; Of course, it is also possible to use other metal compounds or hydrocarbons as precursor. By setting suitable stoichiometric ratios of the starting compounds, the metal carbide can then be deposited directly on the surface of the luminous body, eg according to TaCl ₅ + CH ₄ + x H ₂ -> TaC + 5 HCl + (x - V ₂ ) H ₂ . The hydrogen serves to avoid precipitation of soot. It is also possible to deposit only the metal on the carbon surface of the luminous element and then bring it to reaction (ie carburization) in an atmosphere containing, for example, methane, carburizing from the outer carbon-containing atmosphere and from the inside from the carbon layer starts. A disadvantage of this method, however, is that the change in volume occurring during the conversion of the metal into metal carbide causes relatively high layer stresses. Therefore, a simultaneous deposition of the metal and the carbon in the stoichiometric ratio is advantageous.

In the latter embodiment, the materials of the inner material (e.g., wire) of metal carbide and the outer layer of metal carbide need not necessarily be identical. For example, For example, the inner wire may be tantalum carbide, while the outer layer applied to the carbon layer may be hafnium carbide or HfC-4TaC alloy. HfC or the alloy HfC-4TaC has lower vapor pressures than pure tantalum carbide. However, since hafnium is significantly more expensive than tantalum, the amount of hafnium used can be significantly reduced in this way.

As another source of carbon, sintered carbonaceous materials are contemplated, e.g. in US 3,405,328. There, it is described how metal carbides, such as those produced by sintering processes at high temperatures and high pressures in autoclaves, are used. Tantalum carbide can be made with dissolved carbon forth. These materials, which are intended to serve as the filament material, then contain significantly more carbon than can be expected according to the stoichiometry of the TaC. The patent also describes the use of mixtures of various carbides in order to increase the impact strength of the filament.

Other options for carbon sinks include metals such as WoFram, tantalum, zirconium, etc., which form carbides at suitable temperatures. The operating temperature of these metals depends in particular on the flow of carbon coming from the luminous element; are common in the region between 1800 and 2500 ⁰ C ⁰ C. Preferably, hydrogen is employed in the use of these metals temperatures to the carbon cloth to prevent them from depositing on the bulb wall and to the carbon transport material sink. If the hydrogen were to be dispensed with, carbon transported by the luminous body would precipitate on the bulb wall if it does not accidentally strike the carbide-forming metal on its way from the luminous body. With additional use of hydrogen, the carbon first reacts with the hydrogen to form a hydrocarbon, such as methane, which then decomposes back to the carbide-forming metal to transfer the carbon to the carbide-forming metal and release the hydrogen.

Other possible catalysts for the decomposition of hydrocarbons are aluminum, molybdenum or magnesium silicates.

Another possibility for use as carbon source is the use of tantalum carbide or other carbides. If, for example, a rod of tantalum carbide, which is not flowed through by the current, is brought to a temperature corresponding to the luminous body, the appropriate equilibrium vapor pressure on carbon occurs above the tantalum carbide, in which vaporization or deposition of carbon no longer takes place on the luminous body , This can be achieved, for example, by introducing a bar of tantalum carbide inside the axis of a spiral of tantalum carbide (analogous to a coil with internal feedback, as used for IRC lamps, but with the metal carbide lamps The winding of the current-carrying TaC wire coil must not touch the non-live rod made of TaC in order to avoid a short-circuit. The rod must be at virtually the same temperature as the adjacent turns. In no case may it be significantly colder than the adjacent windings, ie the heat dissipation along the rod must be limited, for example by selecting a sufficiently small diameter. Above the rod, an equilibrium vapor pressure of carbon is established. The carbon becomes in the radially outward concentration gradient at the current carrying TaC Wendeln transported over to the piston wall. The individual turns of the TaC helix are therefore in a constant flow of carbon, the carbon partial pressure corresponding to the equilibrium pressure across the vanes. The carbon transported to the outside reacts again near the piston wall with hydrogen to form hydrocarbons, which then decompose on a suitable catalyst as described above while separating carbon and releasing hydrogen. Overall, therefore, carbon from the rod located on the axis of TaC is transported past the turns of the TaC helix to the carbon sink, with the carbon partial pressure corresponding approximately to the carbon equilibrium pressure at the individual windings and thus stabilizing the turns made of TaC become. In other words, the carbon which evaporates from the individual turns of the TaC helix and is transported outwards is replaced from the inside by the carbon which evaporates from the TaC rod. The advantage of using a rod made of TaC over the use of a rod, for example of pure carbon, is that at the same temperature the carbon vapor pressure over pure carbon is orders of magnitude higher than that over tantalum carbide, thus one would be unnecessary in this case generate strong carbon transport and sometimes even deposit carbon on the TaC helix. The advantage of using a TaC rod on the helix axis, the temperature profile of which as closely as possible corresponds to that of the helix, is that then the carbon equilibrium pressures, which prevent decomposition of the luminous body, are automatically adjusted at the individual windings of the TaC helix.

In addition to the carbon itself and carbon-hydrogen compounds, compounds of carbon with other elements are also suitable as a source of carbon.

Advantageously, for example, carbon and fluorine-containing polymers can be used, as obtained, for example, in the polymerization of tetrafluoroethylene C ₂ F _4. disposal (eg polytetrafluoroethylene PTFE ₁ brand name "Teflon" from the company. DUPONT). In the decomposition of these compounds are formed in the Gas¬ phase compounds such as CF _4, C ₂ F _4, etc. which only at high temperatures close to the illuminant The advantage here is that the carbon is released particularly or practically exclusively at points of high temperature, so that the carbon is transported in a targeted manner to sites of high luminous body temperature Here, relatively low fluxes of carbon or relatively low partial pressures of gaseous CF compounds are used, and the liberated fluorine reacts on the wall to form gaseous SiF ₄ , which then barely intervenes in the reaction process and does not react like hydrogen. because of increased heat conduction negative impact on the effi¬ ciency of the lamp kt. The carbon released can again - unless it is consumed in the wall reaction with CO formation - first bound by means of a transport partner such as chlorine in colder areas and then decomposed on a hot metal wire, the carbon is deposited again and the chlorine is released (carbon sink). Since two F atoms release an O atom in the wall reaction and a C atom in polytetrafluoroethylene in about two F atoms, the carbon is largely converted into CO by the oxygen released in the wall reaction.

The present invention is particularly suitable for low-voltage lamps with a voltage of at most 50 V, because the necessary light body can be made relatively solid and for the wires preferably a diameter between 50 microns and 300 microns, especially at most 150 microns for general lighting purposes with maximum Power of 100 W, exhibit. Thick wires up to 300 μm are used in particular for photo-optical applications up to a power of 1000 W. The invention is particularly preferably used for lamps squeezed on one side, since here the luminous element can be kept relatively short, which also reduces the susceptibility to breakage. But the application to double-sided squeezed lamps and lamps for mains voltage operation is possible. The term rod as used herein means a means formed as a solid rod or, in particular, a thin wire.

The described concept can be applied in a variety of ways to special chemical transport systems. In a specific embodiment, it is used for a design of a carbon-sulfur cycle. As described in DE Az 10358262.2 CS decomposes only at temperatures well above 3000 K, the degree of dissociation of CS increases strongly with increasing temperature. Thus, the CS cycle is suitable for transporting the carbon back to the hottest point along the helix, thus slowing down or preventing the formation of "hot spots." When using this CS system, it should now be borne in mind that the the carbon transporting in the high-temperature range CS at temperatures below about 2200 K dispropor¬ tioned according to 2 CS -> CS ₂ + C, wherein carbon is deposited on the frame or at the Wen¬ delabgängen.On the other hand CS ₂ by diffusion or by When the flow is transported back to places of higher temperature, it decomposes into CS and sulfur at T> 2200 K. The sulfur acts as a decarburizing agent on the metal carbide luminous element, and it is therefore advantageous to have the luminous body or its outlets in the range above 2200 To cover K with a carbon layer, the sulfur atoms liberated in this temperature range then react with the carbon f to CS, decarburization of the metal carbide filament is avoided. Over the life of this carbon coating is slowly consumed. On the other hand, carbon is liberated and deposited at lower temperatures below about 2200 K during the disproportionation of the CS. In summary, therefore, the CS system transports the carbon from places of higher temperature with T> 2200K to places of lower temperature with T <2200 K. Without the reservoir of carbon for T> 2200 K (source) or the deposition of carbon at T <2200 K (sink), it is difficult to achieve stationary operating conditions.

The methodology described here can also be applied to incandescent bodies of materials other than metal carbides, borides or nitrides. As an example, an application to pure metals such as tungsten is described below. In order to produce a life-prolonging regenerative cycle in which "hot spots" on the luminous body are annealed, in the literature the fluoride Circular process described, cf. eg (a) J. Schröder, Kino-Technik no. 2, 1965, (b) Dittmer, Klopfer, Rees, Schroder, J. CS. Chem. Comm, 1973. The regenerative effect of the fluorine cycle process is based on the fact that tungsten fluorides decompose only at temperatures above approximately 2500 K, with the tungsten preferably being redeposited at the hottest points. A major difficulty in using fluorine is that fluorine reacts on the bulb wall to form silicium tetrafluoride SiF ₄ , with additional oxygen being released. The fluorine bound in the SiF ₄ is no longer available for further reaction in the halogen cycle. Therefore, several possibilities for passivation of the piston wall are mentioned in the literature, cf. eg Schröder, PHILIPS Techn. Rundschau 1963/64, p. 359 on the use of Al ₂ O ₃ . Another possibility arises when using the concept discussed here. High molecular compounds of carbon and fluorine, such as polytetrafluoroethylene, are used as fluorine source for this purpose. These compounds decompose slowly at higher temperatures, forming low molecular weight carbon and fluorine containing species in the gas phase. The liberated fluorine reacts on tungsten surfaces in the temperature range between about 1600K and 2400K to form tungsten fluorides. Frame parts or filament outlets made of tungsten present at appropriate temperatures are therefore preferably made thickened in order to be able to provide sufficiently large WoIfram for the cyclic process. The tungsten fluorides thus formed are transported to higher temperature sites where they preferentially decompose at higher temperature sites. Thus, tungsten is deliberately transported back to the hottest places of the filament. When fluorine or fluorine-containing compounds strike the glass wall of the bulb, fluorine reacts to form SiF ₄ and is therefore not available for further participation in chemical transport reactions. The wall reaction also releases oxygen. Since in the polytetrafluoroethylene two fluorine atoms have one carbon atom and in the wall reaction two fluorine atoms each release an oxygen atom, stoichiometrically the oxygen released in the wall reaction can be completely closed by the carbon CO be gotten. Since liberated carbon is usually otherwise bound, for example in the form of carbides, the gettering of the oxygen by the carbon is usually not complete. If necessary, therefore, other getters such as phosphorus must be used. The tungsten fluorides formed at the tungsten reservoir do not become convective or diffuse completely transported in the direction of the luminous element or not fully implemented there; a part is transported in the direction of the piston wall. There, the tungsten fluorides decompose at least in part, releasing fluorine, which reacts with the wall in the manner described, and tungsten. In order to avoid blackening of the lamp bulb, the simultaneous use of bromine is recommended. As a result, tungsten (oxy) bromides can be formed and the bulb wall is kept clean. The tungsten oxybromides decompose at temperatures far below those of the filament. That is, the tungsten bound in them is mainly deposited on the frame or the spiral outlets. This superimposed W-Br (-O) cycle process is thus not regenerative, it only serves to keep the lamp bulb clear.

The basic principle described here - the continuous transport of a substance from a source into a sink - can also be applied to the means of transport, which is used to keep the piston clear and to return material to the filament. Here, the situation may arise that either the transport agent is continuously removed by reaction or absorption with parts of the frame or the piston wall of the gas phase (sink), or that it is continuously introduced by desorption or chemical reaction in the gas phase (source). In order to achieve stationary conditions in the gas phase, it is therefore advisable in such a case, in addition, when a sink occurs a source and additionally introduce a sink in the lamp when a source occurs. As a first example, the continuous transport of hydrogen from a source to a sink is treated. The source of hydrogen may be hydrogen stored in the luminous element (metal carbide), hydrogen taken up in the supply lines or getters (possibly bound as metal hydride, eg tantalum hydride). During the carburization, hydrogen can be enriched in the lamp by the hydrogen partial pressure and the temperature distribution in the luminous element and the supply lines. In lamp operation, other temperature distributions prevail than when carburizing. Typically, the lamp temperature in lamp operation is about 3300 K - 3600 K higher than when carburizing (2800 K - 3100 K); In addition, higher hydrogen partial pressures can be set during carburization. Therefore, when carburizing at a suitable temperature located parts of the frame, for example, tantalum or niobium can absorb hydrogen. Later in lamp operation, these frame parts are at a higher temperature an atmosphere that contains less hydrogen and therefore release hydrogen (source). Parts of the frame located at a significantly lower temperature absorb this hydrogen (sink). For example, in the case of lamps with TaC luminous bodies with integral filament outlets (similar to FIG. 1), the filament outlets during carburizing are not carburized; Thus, tantalum is available in a wide range of tempera- tures, so that in any case there are places that can act as source or sink. Furthermore, quartz glass can serve as a source of hydrogen, which is possible via the setting of a suitable content of OH groups in the glass (via the vacuum annealing of the quartz glass). The filling gas introduced later must take this material rearrangement into account. If necessary, other compounds or metals which are used as hydrogen storage such as zirconium, can be used as sources of hydrogen. These components are attached to the frame or the spiral outlets in such a way that, given the temperatures which occur, hydrogen is released comparatively slowly over relatively long times.

The second example relates to the use of sulfur in a lamp with a metal carbide luminous element and an integral design of filaments and filaments, ie filaments and filament outlets are manufactured integrally from a tantalum wire and then the filament is carburized. When carburizing the helical outlets are not completely mitcarburiert, ie here you will find tantalum or Tantalsubcarbid Ta2C. In this range of lower temperatures, sulfur present in the lamp is converted to the very stable compound tantalum sulfide and the sulfur is thus removed from the gas phase (sink). The the. Gas phase deprived sulfur must be constantly replenished (source) to maintain a CS cycle process. This can be done, for example, by permanent evaporation of CH3CSCH3 from a reservoir impregnated therewith (eg made of rubber). For lamps with extremely low piston temperatures below about 100 ⁰ C elemental sulfur can serve as a source of temperatures even at low Tem¬ has a significant vapor pressure and melts slightly above 100 ⁰ C. The use of higher melting high molecular weight mercaptans as sulfur source is also possible. Brief description of the drawings

In the following, the invention with reference to several embodiments will be erläu¬ tert. Show it:

Figure 1 shows an incandescent lamp with carbide filament according to a Ausführungs¬ example; FIG. 2 shows an incandescent lamp with a carbide luminous element according to a second exemplary embodiment;

Figure 3 to 5 an incandescent lamp with carbide filament according to other Ausfüh¬ insurance examples.

Preferred embodiment of the invention

FIG. 1 shows a bulb 1 pinched on one side with a bulb made of quartz glass 2, a pinch seal 3, and internal current leads 10 which connect foils 4 in the pinch seal to a luminous element 7. The filament 7 is a simple coiled, axially arranged wire of TaC, the ends 14 are uncoiled and projecting transversely to the lamp axis. The outer leads 5 are attached to the outside of the foils 4.

The design described here can also be applied, for example, to lamps with luminous bodies of other metal carbides, e.g. Hafnium carbide, zirconium carbide, niobium carbide. The use of alloys of different carbides is possible. In addition, the use of borides or nitrides, in particular of rhenium nitride or osmium boride, is possible.

In general, the lamp preferably uses a luminous body made of tantalum carbide, which preferably consists of a single-coiled wire. Zirconium carbide, hafnium carbide, or an alloy of different carbides, such as, for example, light-emitting material, which is preferably a coiled wire, is also suitable. in US-A 3,405,328.

The piston is typically made of quartz glass or hard glass with a piston diameter between 5 mm and 35 mm, preferably between 8 mm and 15 mm. The filling is mainly inert gas, in particular noble gas such as Ar, Kr or Xe, possibly with the addition of small amounts (up to 15 mol%) of nitrogen. This is typically a hydrocarbon, hydrogen and a halogen additive.

An addition of halogen is expedient, irrespective of possible carbon-halogen cycle processes or transport processes, in order to reduce the metals evaporated from the metal carbide filament to the precipitate on the bulb wall and, if possible, to transport it back to the filament. This is a metal-halide cycle such as e.g. described in the application DE-Az 103 56 651.1. In particular, the following factor is important: The more the evaporation of carbon from the luminous body can be suppressed, the lower the evaporation of the metallic component, see, for example, US Pat. YES. Coffmann, G.M. Kibler, T.R. Riethof, A.A. Watts: WADD-TR-60-646 Part I (1960).

Concrete embodiments which illustrate the essence of the invention in more detail are set forth below.

(a) Embodiment examples of lamp with TaC luminous body and solid hydrocarbon source

Of the aliphatic hydrocarbons are usually due to the otherwise low melting point only high molecular weight compounds in question (eg, the melting point of C ₅₆ Hn ₄ is just below 100 ° C, which is too little for most applications, unless the use of liquid compounds is possible). Suitable are aromatic hydrocarbons such as, for example, anthracene (melting point 216 ⁰ C), naphthacene (melting point 355 ° C), coronene (melting point 440 ⁰ C), which also have the advantage that considerably per carbon atom less hydrogen in the lamp is registered. For example, the vapor pressure of anthracene is just below the melting point by 50 mbar, at 145 ⁰ C, slightly above 1 mbar. By localizing the source in a range of suitable temperature, it is possible to set a suitable vapor pressure. The vapor pressure of the hydrocarbon has to be adjusted approximately in such a way that the molar concentration of carbon atoms that occurs after its complete decomposition on the TaC luminous body is of the order of the equilibrium concentration of C atoms above the luminous body; the exact value depends on details (eg distance of the C source to the luminous body and to the sink, rate of decay of the hydrocarbons at the sink, etc.). When anthracene is used as the source of carbon, the suitable temperature for the source is in the range between 12O ⁰ C and 150 ⁰ C, when the distance between the luminous body located at eg 3400 K and the source is approx. 3 cm is and the deposition of carbon by Zerset¬ wetting of the hydrocarbons at a at about 400 ⁰ C - 800 ⁰ C hot Ni carried ckeldraht. The cold filling pressure in such a lamp is in the range around 1 bar; the inert gas (eg argon, krypton) preferably contains 2 mbar - 20 mbar hydrogen H ₂ , 0.5 mbar CH ₂ Br ₂ and 2 mbar - 20 mbar iodine. The bromine is intended to prevent the deposition of tantalum on the flask (see DE-A 103 56 651.1), and the iodine is intended to bind the hydrogen released in the course of the evaporation and decomposition of the anthracene in the form of HJ. HJ here represents a sink for the released hydrogen.

Figure 1 shows schematically an example of a possible design of the source and sink for a single-pinched lamp. The source 6 uses as source material a solid hydrocarbon 8 deposited on the end of a wire rod 9, often called a middle holder, of tungsten. The rod 9 is supported by being connected to an additional sheet 11 in the center of the pinch seal 3. For ease of insertion, this can have an outer wire attachment 12, which typically consists of molybdenum.

The sink 13 is realized by coating coils 15 on one or both Stromzu¬ guides 10. These coils consist for example of nickel wire. This can be located in the inner volume, near the pinch, or even protrude into the pinch, as shown on the right helix 15. In this embodiment, have both source and sink at relatively low temperatures, normally, ben betrie¬ below about 500 ⁰ C, such as those found near the bulb wall. With regard to Ein¬ bring the use of the power supply lines 10 near the pinch 3 is the easiest. Alternatively, the source at one Stromzu¬ leadership 10 and the sink could be attached to the other power supply 10.

The end of the middle holder 9 is coated here with the serving as source material hydrocarbon. Although this embodiment is simple to manufacture, it must be accepted that the transport from the source into the sink takes place mainly at the luminous body 7. However, since a certain amount of time is required for the decomposition of the hydrocarbon on the catalyst, which is formed here by the sink of nickel wire, in the stationary state in the entire gas phase, even outside the direct path from the source to the sink , an increased concentration of hydrocarbon or carbon.

An advantage for the operation is therefore the use of an arrangement as in FIG. 2, where the source 16 consists of a holder 18 made of tungsten which is crimped in the pump tip 17, at whose end facing the filament 7 the source material 19 is seated, namely a hydrocarbon which was precipitated as a solid.

The sink is here realized by the lower part 21 of the current supply 22, which is close to the pinch. This part 21 consists of molybdenum, which serves as Kata¬ analyzer in the decomposition of hydrocarbons. The upper part 20 of the power supply is integrally formed by the carbide of the filament. The lower parts 21 protrude into the pinch.

In this geometric arrangement, the luminous element 7 is in the material flow, which forms from the source 16 to the sink 21. In FIG. 2, the lower part of the inner power supply 22 is made of molybdenum, which is known as molybdenum Catalyst in the decomposition of hydrocarbons and thus acts as a sink.

(B) Embodiment of a lamp with a luminous body of TaC and with a carbon source

The luminous body 23 consisting of TaC, see FIG. 3, is operated at a temperature between 3300 K and 3600 K. To generate a suitable carbon partial pressure at the location of the TaC luminous body, the carbon source 24 is maintained in the temperature range between 2700 K and 3000 K. Hydrogen is added to the inert gas (krypton, argon) in such a way that the partial pressure of the hydrogen is in the range preferably between 2 mbar H ₂ and 20 mbar H to avoid the deposition of the carbon on the piston wall and the transport of the carbon to the sink ₂ lies. In this case, no hydrogen is released from the source, so that no sink for hydrogen is needed. The carbon source is at such a high temperature that there is no direct reaction with the hydrogen. As a sink for the decomposition of the hydrocarbon is, for example, again at 400 ⁰ C - 800 ⁰ C operated wires or plates of nickel or iron or molybdenum, or at temperatures around 500 ⁰ C be¬ exaggerated aluminosilicate.

FIG. 3 shows a possible geometry for such a lamp. C deposits in the "upper" region of the current feeds 25 near the transition region to the helix 23, where comparatively high temperatures already exist, act as the carbon source 24. Depending on the embodiment of the helix with regard to the helix temperature profiles, carbon deposition can also take place The current supply is here an integral departure from the helix 23. Instead of the C deposits, C fibers can also be wound around the outlet, the depression 26 here being a coating helix of iron coated with platinum It is close to the bruise, so it is appropriate at very high temperatures. (c) Example of a geometry with a source located on the helical axis

An example of a source arranged on the axis of the luminous element is shown in FIG. Here is an existing TaC rod 27 in the lamp axis, which is also the axis of the lamp. The rod 27 has approximately the same temperature profile in the region of the helix 28 as the helix itself. The helix is wound to such an extent that the rod 27 fits snugly into its axis. The depression is again formed by coating helices 26, as in FIG. 3. They consist of molybdenum. The rod 27 is supported by a middle holder 9 similar to FIG. In particular, it can extend into a pump seat 29, see dashed embodiment. As a result, he is better locked.

(d) Example of use with a double-ended bulb

FIG. 5 shows a possible arrangement for a double-sided squeezed lamp 30. Here, one can advantageously arrange the source 31 and the sink 32 on the different sides of the luminous element 33 so that the luminous element 33 is in the transport stream from the source due to the geometric arrangement 31 to the sink 32 is located. The bruises are designated 39.

The source 31 is a carbon deposit (soot) or a carbon fiber wound around the power supply 34. The sink 32 is the part of a power supply, which is made of molybdenum and is arranged away from the luminous body 33. This part is connected via a weld point 35 to the outlet 36 of the luminous body made of TaC.

Advantageously, the entire temperature spectrum is available on both sides of the luminous element 33 in the axial direction, so that, for example, the C source at relatively high temperatures in the vicinity of the filament and the sink at lower temperatures farther away from the filament on the other side can be arranged. In the example shown in FIG. 5, the molybdenum outflow acts as a sink. As the filament material is a metal or a metal compound is suitable, the melting point in the vicinity of the melting point of tungsten, preferably at least 3000 ⁰ C, and more preferably above that of tungsten. Besides tungsten, rhenium, osmium and tantalum are particularly suitable.

Claims

claims

1. Incandescent lamp with a luminous body, which contains a high-temperature-resistant metal compound (7) and with power supply lines (10) which hold the Leucht¬ body (7), wherein the filament is introduced together with a filling in a piston (2) vacuum-tight, wherein the material of the filament is a metal or a metal compound, in particular a metal carbide, comprising, des¬ sen melting point near the melting point of tungsten, preferably at least 3000 ⁰ C and particularly preferably above that of tungsten, is located, characterized in that the luminous body contains a material which, due to chemical decomposition and / or vaporization, becomes depleted during operation on at least one chemical element, and that in the piston a

Source is provided and a sink for this element, wherein the source provides the element at which the luminous body is depleted and wherein at the sink, the element which the luminous body continuously emitted during the lifetime Dauer¬, is deposited, so that it is a total of one continuous flow of the element described comes from the source to the sink, wherein the concentration of the element in question, apart from on running processes, is substantially stationary at each location in the lamp, the luminous body in stationary operation with the au¬ of Shen through the Interaction of source and sink imprinted partial atmosphere from the constantly transported in him element in the

Balance is such that a depletion of the filament is prevented at the element in question.

2. Incandescent lamp according to claim 1, characterized in that the luminous body is surrounded by a piston made of glass, in particular quartz glass or hard glass, or ceramic, in particular Al ₂ O ₃ .

3. Incandescent lamp according to claim 1, characterized in that the filling at least one base gas in the form of an inert gas, in particular noble gas and / or nitrogen used.

4. Incandescent lamp according to claim 1, characterized in that the metal connection is a metal carbide, such as e.g. Tantalum carbide, zirconium carbide or hafnium carbide or alloys of various metal carbides is.

5. Incandescent lamp according to claim 4, characterized in that the source consists of a solid or liquid hydrocarbon or halogenated Kohlen¬ hydrogen, which is operated in the temperature range between 100 ⁰ C and 400 ⁰ C, and which releases carbon in the decomposition.

6. An incandescent lamp according to claim 4, characterized in that the source of Koh lenstoff, in particular of carbon black or graphite fibers or fabrics or carbon lenstoffpresslingen exists, wherein the transport of the carbon to Sen¬ ke by additionally introduced material, as part of Filling, from the group hydrogen and / or halogen takes place, this material reacts in colder areas with the carbon to hydrocarbons or halo¬ genierten hydrocarbons, said hydrocarbon decomposes again at the sink with deposition of the carbon and release of the transport.

7. Incandescent lamp according to claim 4, characterized in that the source of ei¬ nem coated with the corresponding metal carbide graphite body, in particular graphite fiber, wherein the transport of the carbon to the sink by additionally introduced material, as part of the Fül¬ ment, from the Group of hydrogen and / or halogen takes place, this material reacts in colder areas with the carbon to hydrocarbons or halogenated hydrocarbons, said Kohlenwas¬ hydrogen decomposes again at the sink with deposition of the carbon and release of the transport means.

8. Incandescent lamp according to claim 4, characterized in that the source consists of ei¬ nem carbon-containing sintered material, wherein the transport of the carbon to the sink by additionally introduced material, as Component of the filling, from the group hydrogen and / or halogen er¬ follows, which reacts in colder areas with the carbon to hydrocarbons or halogenated hydrocarbons, said hydrocarbon decomposes again at the sink with deposition of the carbon and release of the transport ,

9. Incandescent lamp according to claim 4, characterized in that as the source of the carbon, a rod fixed in the vicinity of the filament, in particular an axially arranged rod, of the same metal carbide as the Leucht¬ body is used, the longitudinal temperature profile of that of the same Metal carbide existing luminous body corresponds, and hydrogen and optionally halogen, is used as means for transporting the carbon to the sink.

10. An incandescent lamp according to claim 1, characterized in that as a source of carbon, a rod attached in the vicinity of the axis of the filament of a second metal carbide whose vapor pressure at a given temperature is higher than that of the metal carbide of the filament to the losses by thermal conduction along the wire fixed in the axis of the helix, and hydrogen, and optionally halogen, is used as a means of transporting the carbon to the well.

11. Incandescent lamp according to one of claims 5 to 10, characterized in that the depression for the carbon consists of a catalytically active metal, in particular nickel or iron or molybdenum or cobalt or platinum, be¬ at which the, if necessary halogenated, hydrocarbons with removal of carbon and release of hydrogen and, if necessary,

Decompose halogen.

12. Incandescent lamp according to one of claims 5 to 10, characterized in that the depression for the carbon consists of a carbide-forming metal, in particular of iron or molybdenum or tungsten or tantalum or Ni ob, to which the hydrocarbons to form Metallkarbi - decompose and release hydrogen.

13. Incandescent lamp according to one of claims 5 to 10, characterized in that the sink for the carbon consists of aluminum, magnesium or molybdenum di-silicates.

14. Incandescent lamp according to one of claims 11 to 13, characterized in that the filling contains iodine, wherein the released hydrogen is bound by Re¬ action with iodine to hydrogen iodide, so that the iodine has the Funktion tion of a gaseous sink for the hydrogen ,

15. Incandescent lamp according to one of claims 11 to 13, characterized in that the released hydrogen escapes through the hot quartz piston wall, so that the sink for the hydrogen is provided by the permeation of the hot piston wall.

16. Incandescent lamp according to one of claims 11 to 13, characterized in that in the piston is introduced to a hydrogen-affine metal, wherein the released hydrogen from the affine to hydrogen metal, in particular zirconium or hafnium or niobium or tantalum, bound or " is "being pounded.

17. Incandescent lamp according to claim 4, characterized in that the source is a fluorinated, in particular perforated, hydrocarbon, in particular PTFE is used, which supplies at high temperatures as decomposition products perfluorinated carbon compounds.

18. Incandescent lamp according to claim 17, characterized in that the carbon is transported by means of halogen, preferably chlorine, to the sink, which consists of ei¬ nem catalytically active metal or a carbide-forming metal, in particular nickel, iron, molybdenum, cobalt, platinum, tungsten or tantalum.

19. Incandescent lamp according to one of the preceding claims, characterized gekenn¬ characterized in that the filling gas additionally contains a halogen-containing compound, and optionally hydrogen, sulfur or a cyanide-containing compound to the metal and optionally the carbon, at the deposition on the piston wall to prevent and as completely as possible to transport the filament back.

20. Incandescent lamp according to claim 4, characterized in that the luminous body is coated with the material to which it is depleted and which is to be supplied from a source again, and forms a first layer and then a second layer of the actual filament material of outside on this first

Layer is applied.

21. An incandescent lamp according to claim 4, characterized in that the source of a first coated with carbon in a first layer and then coated with metal carbide in a second layer body of the same or another metal carbide, wherein the transport of the carbon to the sink by additionally introduced material, as part of the filling, from the group of hydrogen and / or halogen takes place, said material in colder areas with the carbon to hydrocarbons or halogenated hydrocarbons rea¬ giert, said hydrocarbon at the sink with deposition of the carbon and Release of the transport again decomposed.

22. An incandescent lamp according to claim 21, wherein the outer second layer is an alloy of different metal carbides, preferably an alloy of tantalum carbide and hafnium carbide.

23. An incandescent lamp according to claim 4, wherein the source of pure carbon or a carbon-containing compound ge according to one of the preceding claims ge forms, while the sink by release of carbon on the frame, which is chemically indifferent here in a limited temperature range by a Gas phase reaction system is realized.

24. An incandescent lamp according to claims 4 and 23, characterized in that the carbon-sulfur system is used for recycling the carbon to the luminous element, and on the frame at a position in operation temperatures above 2150 K, preferably above about 2200th K, particularly preferably above 2250 K, a carbon coating is applied as the source, and that, moreover, the sink due to the disproportionation reaction in the CS system at temperatures below 2250, preferably below about 2200 K, particularly preferably below 2150 K, is realized.

25. Incandescent lamp according to claims 1 to 3, wherein the luminous body consists of a metal.

26. An incandescent lamp according to claim 25, characterized in that the luminous body consists of tungsten, and a high molecular weight compound containing carbon and fluorine slowly decomposes over the life of the lamp, wherein fluorine is released, which at one in the temperature range between 1600 K and 2400 K. attached tungsten reservoir reacts to tungsten fluorides and thus has the function of a source which transports tungsten preferably to the hottest places on the luminous body, and wherein the fluorine from the not converted to the filament tungsten fluorides on the piston wall to gaseous SiF ₄ or the tungsten reacts is deposited by a superimposed bromine cycle on colder parts of the frame and thus has the function of a sink for tungsten and fluorine.

27. An incandescent lamp having a luminous element made of a metal or a high-temperature-resistant metal compound, surrounded by a piston made of quartz glass, hard glass or ceramic, the piston containing a filling which contains at least one inert gas. contains gas and a chemical transport means, wherein inert gas and / or nitrogen are used as inert gas, characterized in that the chemical transport, which is used for clearing the piston or for returning the material to the luminous body, continuously exits from a source and in a Sink is bound, which adjusts after a start-up phase statio¬ nary concentration in the gas phase.

28. Incandescent lamp according to claim 27, wherein the luminous body is made of a metal carbide and a carbon-hydrogen cyclic process is used to keep the piston wall free, characterized in that the hydrogen constantly consists of hotter places of tantalum or niobium or zirconium Frame itself or the luminous body exits and is bound to colder parts of the also consisting of said metals parts of the frame again, or diffused at higher temperatures through a piston wall made of quartz back to the outside.

29. Incandescent lamp according to claim 27, wherein the luminous body is made of a metal carbide and a carbon-hydrogen cyclic process is used to keep the piston wall free, characterized in that the hydrogen exits from the hot bulb wall made of quartz with an increased OH content and at colder parts of tantalum, niobium or zirconium parts of the frame.

30. The incandescent lamp as claimed in claim 27, wherein the luminous body is made of a metal carbide and the carbon-sulfur transport system is used to return the carbon to the incandescent body, characterized in that, on the one hand, the sulfur is preferentially precipitated at the colder places On the other hand, however, it is permanently supplied by the evaporation of pure sulfur, sulfur-containing organic substances, such as CH ₃ CSCH ₃ or mercaptans, to permanent parts of the frame or filament outlets.