Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/24—After-treatment of workpieces or articles
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
  • C23C14/14—Metallic material, boron or silicon
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F5/006—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of flat products, e.g. sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
  • B22F7/002—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of porous nature
  • B22F7/004—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of porous nature comprising at least one non-porous part
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
  • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
  • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
  • B22F7/08—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools with one or more parts not made from powder
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
  • C23C14/14—Metallic material, boron or silicon
  • C23C14/16—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon
  • C23C14/165—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon by cathodic sputtering
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
  • C23C14/3414—Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/58—After-treatment
  • C23C14/5806—Thermal treatment
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/4401—Means for minimising impurities, e.g. dust, moisture or residual gas, in the reaction chamber
  • C23C16/4404—Coatings or surface treatment on the inside of the reaction chamber or on parts thereof
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C24/00—Coating starting from inorganic powder
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C24/00—Coating starting from inorganic powder
  • C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
  • C23C24/082—Coating starting from inorganic powder by application of heat or pressure and heat without intermediate formation of a liquid in the layer
  • C23C24/085—Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
  • C23C24/087—Coating with metal alloys or metal elements only
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
  • H01J1/02—Main electrodes
  • H01J1/13—Solid thermionic cathodes
  • H01J1/14—Solid thermionic cathodes characterised by the material
  • H01J1/142—Solid thermionic cathodes characterised by the material with alkaline-earth metal oxides, or such oxides used in conjunction with reducing agents, as an emissive material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J61/00—Gas-discharge or vapour-discharge lamps
  • H01J61/02—Details
  • H01J61/04—Electrodes; Screens; Shields
  • H01J61/06—Main electrodes
  • H01J61/073—Main electrodes for high-pressure discharge lamps
  • H01J61/0735—Main electrodes for high-pressure discharge lamps characterised by the material of the electrode
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
  • H01J9/02—Manufacture of electrodes or electrode systems
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
  • H01J9/02—Manufacture of electrodes or electrode systems
  • H01J9/04—Manufacture of electrodes or electrode systems of thermionic cathodes
  • H01J9/042—Manufacture, activation of the emissive part
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/24—After-treatment of workpieces or articles
  • B22F2003/241—Chemical after-treatment on the surface
  • B22F2003/242—Coating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

• the invention relates to a high-temperature component made from a refractory metal or a refractory metal alloy having the features of the preamble of claim 1 and a method for producing a high-temperature component.
• the heat generated in the component is emitted to the environment by thermal radiation.
• the emitted energy is proportional to the thermal emissivity of the radiating surface. This value indicates how much radiation a body emits in relation to an ideal black body. The higher the thermal emissivity of a surface, the more thermal radiation power a body can emit via this surface.
• thermal radiant power since the emission and absorptivity of a body are proportional, a body with a high degree of thermal emissivity also absorbs more radiant power than a body with a lower degree of thermal emissivity.
• WO2014023414 (A1), in which a heating conductor with a porous sintered coating made of tungsten applied by means of a slurry process is described. Due to the porous sintered coating made of tungsten, the thermal emissivity in the wavelength range 1700-2500 nm can be improved to approx. 0.34; in comparison, the thermal emissivity of a smooth tungsten surface at room temperature is around 0.16 in this wavelength range.
• EP1019948 (B1) describes an anode of a high-pressure gas discharge lamp which is provided with a metallic coating with a dendritic structure.
• the needle-shaped crystallites of the dendritic structure also increase the surface area of the anode.
• a thermal emissivity of up to 0.8 can be achieved.
• dendritic structures are very complex and expensive to produce.
• a general disadvantage of the aforementioned coating solutions with structures in the lower ⁇ m range is the degradation of the coatings with increasing service life. Particularly at operating temperatures >1500°C, the surface area is constantly reduced due to the sintering process and the associated reduction in the degree of thermal emission. Approaches in which the surface is structured on a scale of several 100 ⁇ m, for example by means of a laser, so that sintering processes can be avoided, are very cost-intensive.
• WO2018204943 (A2) describes a high-temperature component made from a refractory metal with a coating that contains tantalum nitride and/or zirconium nitride and tungsten with a tungsten content of between 0 and 98% by weight. (weight percent). A thermal emissivity of up to 0.8 can be achieved.
• DE102009021235 (B4) discloses an electrode for a discharge lamp with a coating in which tungsten particles are embedded in a ceramic matrix layer.
• Both of the aforementioned coatings have in common that they are not suitable for thermally highly stressed components such as heating conductors that are used in coating systems, in particular MOCVD systems (Metal-Organic Chemical Vapor Deposition) and are exposed to temperatures >2000° C. during operation .
• MOCVD systems Metal-Organic Chemical Vapor Deposition
• US 2002/0079842 (A1) describes an electrode for a high-pressure gas discharge lamp that is coated with rhenium. Rhenium has a higher thermal emissivity compared to tungsten, but it is very expensive. Tungsten can be added to the applied rhenium for cost reasons. The thermal emissivity of the resulting mixture decreases by adding tungsten compared to pure rhenium.
• the object of the present invention is to further develop high-temperature components and to provide a method for producing the same.
• the high-temperature component should be characterized by a high degree of thermal emission and be suitable for operating temperatures around or higher than 2000°C.
• the applications considered in this application are applications with operating temperatures of typically 1000-2500°C or above. This includes, in particular, applications in lighting technology (e.g. electrodes in high-pressure discharge lamps), furnace technology (e.g. heating conductors, furnace installations, charging devices, crucibles) and medical technology (e.g. rotary X-ray anodes).
• lighting technology e.g. electrodes in high-pressure discharge lamps
• furnace technology e.g. heating conductors, furnace installations, charging devices, crucibles
• medical technology e.g. rotary X-ray anodes
• Refractory metals or refractory metal alloys are generally used for the high-temperature applications mentioned.
• refractory metals are the metals of group 4 (titanium, zirconium and hafnium), group 5 (vanadium, niobium, tantalum) and group 6 (chromium, molybdenum, tungsten) of the periodic table and rhenium Roger that.
• Refractory metal alloys are alloys with at least 50 at. % (atomic percent) of the element in question. Among other things, these materials have excellent dimensional stability at high operating temperatures.
• the high-temperature component is based on refractory metal or a refractory metal alloy.
• the high-temperature component consists essentially, i.e. at least 50 at.%, preferably more than 95 at.%, of refractory metal.
• the high-temperature component particularly preferably consists entirely of refractory metal or refractory metal alloy and the usual impurities. Attachments can be attached to the actual high-temperature component.
• the high-temperature component can be part of a composite component, for example.
• a material that is particularly preferred for the high-temperature component due to its heat resistance is tungsten or a tungsten alloy.
• a generic high-temperature component has a coating to increase the thermal emissivity.
• the coating can be applied to the entire component or only to parts of it.
• the coating for increasing the thermal emissivity essentially consists of tungsten and rhenium, the proportion of rhenium being at least 55% by weight and the proportion of tungsten being at least 10% by weight (limit values included).
• the proportion of rhenium is between 55 wt.% and 90 wt.%, remainder Tungsten;
• the proportion of rhenium is preferably between 60% by weight and 85% by weight, and the proportion of rhenium is particularly preferably between 65 and 80% by weight.
• Essentially here means that the main components are tungsten and rhenium.
• the coating may contain small amounts of other components and common impurities. Oxides, nitrides or carbides, as well as metals such as molybdenum, iron, copper, tantalum and niobium can be present as impurities.
• the proportion of the main components tungsten and rhenium is preferably more than 95% by weight, in particular more than 98% by weight.
• tungsten and rhenium are at least partially present in the coating in the form of a cubic ReBW phase, ie the coating has a cubic ReBW phase of at least 35 wt.%, in particular at least 40 wt.%, particularly preferably at least 50 wt. %, very particularly preferably at least 70% by weight.
• ReBW is an intermetallic phase with a cubic crystal system and, apart from the lattice constant, is equivalent to the cubic Reo.75Wo.25 phase.
• the ReßW phase is also understood to mean the cubic Reo.7sWo.25 phase.
• phase diagram The various phases in the tungsten-rhenium binary phase diagram can be seen in FIG. Phases in which the material is in solid solution form are bracketed, phases without brackets are intermetallic phases. In contrast to mixed crystals, these show lattice structures that differ from those of the constituent metals and in which there is a mixed bond between the individual metal atoms consisting of a metallic bond component and lower atomic bond or ionic bond components.
• the Rez ⁇ N phase (or Reo.7sWo.25 phase) is denoted by c in the phase diagram.
• the thermal emissivity of tungsten with a smooth surface is at Room temperature in the wavelength range 1700-2500 nm approx. 0.16, the corresponding thermal emissivity of rhenium is approx. 0.18.
• the person skilled in the art would therefore expect - see also US200200779842 (A1) - that the degree of thermal emission decreases with a decreasing proportion of rhenium. Surprisingly, however, this is not the case.
• a representative sample is taken from the coating, ground to a powder and the powder obtained is analyzed by means of XRD (from English X-ray diffraction, X-ray diffractometry).
• the degree of thermal emission which is due to the material properties of the coating, can also be increased by measures to enlarge the microscopic surface.
• the coating is preferably porous.
• Porous here means that the coating has a considerable proportion of pores, for example more than 5%.
• the proportion of pores is understood to mean the area proportion of the pores in a total cross-sectional area and it is determined using a representative sectional area of a coating sample. Due to the pores present in the volume of the coating, the surface of the Coating enlarged compared to the purely geometric surface, which also increases the thermal emission level.
• a porous coating can be produced, for example, by means of powder metallurgy methods.
• the surface of the high-temperature component to which the coating is applied can already be enlarged compared to the purely geometric surface.
• the surface of the high-temperature component is structured below the coating and is therefore enlarged.
• the structuring can be done by a mechanical, chemical or thermal process.
• the coating itself is not necessarily porous.
• the pretreatment of the surface of the high-temperature component is of particular interest for PVD (physical vapor deposition) coating processes.
• the coating is designed as a sintered layer.
• a sintered layer is understood to mean a layer that is obtained by a powder-metallurgical coating process.
• a slurry coating is mentioned as an example of a powder-metallurgical coating process.
• the layer application is consolidated by sintering.
• a sinter layer is usually porous and has a rough surface.
• the coating can also be in the form of a PVD layer.
• the coating is produced on the surface of the high-temperature component using a suitable sputtering target in a physical vapor deposition process.
• a PVD layer is usually smooth and dense, i.e. it has no pores.
• the surface of the high-temperature component can be structured before coating using a mechanical, chemical or thermal process.
• a sintered layer preferably has a thickness between 2 ⁇ m and 300 ⁇ m, more preferably between 3 ⁇ m and 100 ⁇ m, particularly preferably between 5 ⁇ m and 50 ⁇ m.
• the thickness can also be significantly lower. Typical thicknesses of PVD layers are between 10 nm and 4 pm.
• the thickness of the coating is not critical to performance.
• the coating is preferably formed on the top side of the high-temperature component. This means that the coating forms the outermost layer on the surface of the high-temperature component. When the high-temperature component is used, this layer is intended to take part in heat transfer by means of radiation.
• the high-temperature component is designed as a heating conductor.
• heating conductors mean metallic resistance heaters, such as are used in heat treatment systems. Heating conductors can be formed from sheet metal, bar stock, twisted wire, bundled wire or wire mesh. In the case of flat heating conductors, ie heating conductors whose basic shape comes from sheet metal, it may be desirable to provide the coating only on that side of the heating conductor which faces the interior of a furnace during operation of the heating conductor.
• the coating When used on a heating conductor, the coating has the effect that this can provide a specified heating output at a lower temperature due to the improved heat radiation.
• a lower operating temperature of the heating conductor is advantageous with regard to the service life, since creeping of the material can be reduced as a result, for example.
• heating conductors that are used in coating systems, in particular MOCVD systems, is particularly interesting. Due to the high operating temperatures of > 2000°C, there is a risk of the heating conductor material evaporating and the associated risk of possible contamination during the coating process. After the current In the prior art, these heating conductors are made either from tungsten or from rhenium, with the heating conductors that are subjected to the highest thermal loads being made from rhenium. Both materials have a low vapor pressure at high temperatures, but differ in their thermo-mechanical properties. For this reason, the more expensive rhenium is preferred to the less expensive tungsten for certain applications.
• the coating according to the invention allows the degree of thermal emission of a tungsten heating conductor to be increased and the surface temperature to be reduced to such an extent that the field of application can be significantly expanded.
• a heating element made of tungsten coated with rhenium and tungsten according to the present invention is an economically very attractive alternative to a heating element which is made entirely of rhenium and is correspondingly expensive. Due to the comparatively high degree of thermal emission, it can be operated at a comparatively lower temperature for a given heating output.
• the invention allows, in certain applications, a substitution of a tungsten heating conductor by a heating conductor based on molybdenum and coated with rhenium and tungsten according to the present invention.
• the high-temperature component is designed as an electrode of a high-pressure discharge lamp, in particular as an anode of a high-pressure discharge lamp. Due to the coating of the electrode according to the invention, in particular the anode, this can radiate more heat during operation, which leads to a reduced component temperature and has an advantageous effect on the service life. According to another embodiment, the
• High-temperature component designed as a crucible.
• Crucibles made of refractory metal are used, for example, to melt aluminum oxide in the production of sapphire single crystals.
• the crucibles are placed in a high-temperature furnace and heated by heating conductors using radiant heat.
• the heat transfer takes place mainly via the lateral surfaces of the crucible, which absorb the radiant heat and pass it on to the material to be melted.
• a larger proportion of the heat given off by the heating conductors couples into the crucible.
• the thermal emissivity of the coating is preferably e>0.6, measured at room temperature and for a wavelength range between 1700-2500 nm, as explained in more detail below.
• the invention also relates to a method for producing a high-temperature component.
• the method for producing a high-temperature component comprises the steps:
• the base body is understood to mean the high-temperature component or the semi-finished product from which the component is made before coating.
• process variant i) and ii) are based on a PVD process
• process variant iii) is based on a powder-metallurgical process.
• a surface of the base body of the high-temperature component is preferably first pretreated in such a way that the surface is enlarged compared to the geometric surface.
• This "roughening" can be caused by material removal at the Surface done, for example, by the surface is structured by a mechanical method, eg (sand) blasting, chemical (eg etching or pickling) or thermal method (eg laser structuring).
• the surface area can also be increased by a slurry coating.
• powdery components are slurried in a liquid.
• Components here the base body of a high-temperature component
• the resulting suspension which generally also contains binders, by dipping, spraying or brushing or the like. After drying, the coating is usually sintered.
• the coating formed in this way is usually porous and rough. It forms a favorable base for a subsequent coating.
• the slurry coating can be based on tungsten powder, for example.
• tungsten and rhenium are applied to the base body—which may have an enlarged surface—by means of physical vapor deposition.
• Target material containing tungsten and rhenium and having the appropriate composition can be used as the source, with the desired ReBW phase already being present in sufficient quantity in the target material.
• the preferred rhenium content in the layer can be set by suitably selecting the target composition.
• two or more target materials can alternatively be used, one predominantly or exclusively consisting only of ReBW Phase consists and to set the desired tungsten-rhenium concentration one or more additional target materials made of tungsten and / or rhenium with appropriate tungsten-rhenium composition are provided.
• the target material preferably has the cubic ReBW phase to an extent of at least 35% by weight. More preferably, the proportion of ReBW phase is at least 40% by weight, particularly preferably at least 50% by weight, very particularly preferably at least 70% by weight. As a result, the PVD coating has a rhenium content of between 55% by weight and 90% by weight, the remainder being tungsten, with the proportion of ReBW phase being at least 35% by weight.
• This process variant i) (PVD coating with ReBW phase) can be advantageous if warping of components with narrow component tolerances is to be avoided.
• the PVD coating takes place at comparatively low temperatures and does not require any heat treatment of the coating.
• Process variant ii) is also a PVD coating process and differs from variant i) in that a ReBW phase is not necessarily present in the target material, but rather the ReBW phase is only formed later by heat treatment in the sputtered layer.
• the base body coated by a physical vapor deposition process is subjected to annealing at a heat treatment temperature which is in the phase field of the ReBW phase.
• the heat treatment temperature is at least 500°C, technologically preferably at least 1000°C, more preferably above 1800°C.
• the duration of the heat treatment depends on the heat treatment temperature.
• the stipulation in the selection of the heat treatment parameters is to set a content of ReBW phase in the coating of at least 35% by weight by means of the heat treatment.
• the heat treatment should result in a content of ReßW phase in the coating of at least 40% by weight, particularly preferably of at least 50% by weight, very particularly preferably at least 70% by weight.
• An inert atmosphere is provided by inert gases such as nitrogen or argon at a pressure of about 1 bar, and a reducing atmosphere by hydrogen, for example.
• a high vacuum is understood to mean a vacuum with a pressure of 10 3 -10 8 mbar.
• the coated base body is preferably slowly cooled from the heat treatment temperature to approx. 800° C. and from approx. 800° C. rapidly cooled to room temperature.
• the slow cooling to a temperature below the heat treatment temperature but still in the phase field of the ReBW phase can be technologically advantageous in order to protect the heat treatment system used.
• the Rez ⁇ N phase which is metastable at room temperature, is kinetically stabilized by the rapid cooling.
• slow cooling means cooling on a time scale of a few hours, corresponding to cooling rates between 1 K/min and 10 K/min, typically below 10 K/min.
• rapid cooling means quenching at cooling rates in the range of typically 20 to 150 K/min, preferably greater than 25 K/min, more preferably greater than 50 K/min, particularly preferably greater than 100 K/min.
• Process variant ii) has the advantage over process variant i) that no target material containing ReßW is required (however, of course, a target material that already contains Rez ⁇ N has to be used).
• the disadvantage is the additionally required heat treatment step at comparatively high temperatures.
• the base body is initially coated with a powder mixture containing rhenium and tungsten (molar ratio of tungsten to rhenium around 1:3) using a powder metallurgical process and then - analogously to process variant ii) - the heat treatment (i.e. Annealing to form the ReßW phase, rapid cooling to stabilize the ReßW phase).
• Rhenium or tungsten-containing means here that the powder contains rhenium or tungsten in metallic form.
• the powder mixture can also contain other components such as binders.
• the powder metallurgical process can in particular be a slurry process.
• the heat treatment consolidates the layer applied by powder metallurgy and due to the comparatively long process time of approx process times of 3-10 hours used with these metals would be in a mixed crystal form, converted to the intermetallic ReBW phase.
• the coated base body is optionally cooled slowly to 800° C. and then rapidly cooled to room temperature.
• the parameters of the heat treatment and cooling correspond to the parameters in process variant ii).
• the ReßW phase which is metastable at room temperature, is kinetically stabilized by the rapid cooling.
• FIGS. 2a-2d scanning electron micrographs of surfaces coated according to the invention in cross section (fracture surfaces) (FIGS. 2a and 2c) and in plan view (FIGS. 2b and 2d),
• Fig. 4a, 4b X-ray diffractograms (XRD) of a layer according to the invention and a conventionally produced layer
• Fig. 5 schematically a high-pressure discharge lamp as
• FIG. 6 shows a heating conductor as an exemplary embodiment
• base bodies made of tungsten were coated with slurries of different powder mixtures.
• tungsten or rhenium powder was first weighed into a binder of 2% by weight ethyl cellulose in ethanol to a total solids content of 50%. It was stirred in using a Netzsch Multimaster at 1500 rpm for 15 minutes.
• weight percentages given here relate to the weight of the solid components rhenium and tungsten and also correspond to the weight percentages in the layer, since the organic components volatilize during the heat treatment.
• the dried layer was then subjected to a heat treatment (annealing).
• Organic components e.g. binders
• binders e.g. binders
• Each heat treatment was performed at 1800°C for 20 hours under an argon (Ar) atmosphere.
• the coated base body is slowly cooled step by step over a period of 10 hours to 800°C (corresponding to an average cooling rate of 1.67 K/min) and from approx. 800°C to room temperature within 20 minutes (corresponding to an average cooling rate of around 40 K/min).
• the thermal emissivity of the layers was measured using a Solar 410 Reflectometer from Surface Optics Corporation at room temperature and for a wavelength range between 1700-2500 nm, since this infrared wavelength range is particularly relevant for assessing the thermal radiation of a body.
• Sample #1 a porous tungsten coating obtained with 100% tungsten slurry has a thermal emissivity of 0.34
• Sample #2 a porous rhenium coating obtained with 100% rhenium slurry has a thermal emissivity of 0.36
• Sample No. 3 is a coating of tantalum nitride that has been produced in accordance with the applicant's WO2018204943. This has a comparatively high thermal emissivity of 0.89, but it can only be used for temperatures up to a maximum of 1500°C.
• Sample #4 exhibits an 80% rhenium, 20% tungsten coating prepared as described above for comparison purposes with a heat treatment at 1600°C for 6 hours.
• this sample primarily has tungsten/rhenium mixed crystals and only a very small proportion of the Rez ⁇ N phase. It has a thermal emissivity of 0.35.
• Sample #5 is an 80% rhenium, 20% tungsten coating prepared according to the instructions previously described (heat treatment at 1800°C for 20 hours). The proportion of ReBW phase is about 90% by weight. The thermal emissivity was determined to be 0.66.
• Figures 2a to 2d show scanning electron micrographs of Sample No. 5.
• Figures 2a and 2b are an image magnified 1000 times
• Figures 2c and 2d are an image magnified 3000 times.
• Figure 2a and Figure 2c shows a fracture surface normal to the surface of the sample
• Figures 2b and 2d are a plan view of the surface, ie the viewing direction is normal to the coated surface.
• the substrate 2 made of tungsten sheet material can be seen at the fracture surfaces in the lower part of the figure.
• the porous coating 3 can be seen above it.
• the porosity increases the microscopic surface area and contributes to a further increase in the thermal emissivity.
• FIG. 3 shows a diagram of the measured thermal emissivities epsilon (s) for the test series mentioned at the outset with different rhenium contents.
• the rhenium content is plotted on the abscissa, and the measured thermal emissivity epsilon (s) is plotted on the ordinate.
• the points in the diagram denote the respective measured values.
• the dashed line sth (theoretical epsilon) marks the thermal emissivity values that would be expected if one were to linearly interpolate the thermal emissivity from 100 wt.% tungsten to 100 wt.% rhenium.
• the measured values for the thermal emissivity surprisingly do not run along this straight line sth, but lie above it, in some cases very clearly above it.
• Table 2 shows the results of a detailed quantitative phase analysis for samples with a rhenium content of 70% by weight (sample I) and 80% by weight (sample II).
• sample I rhenium content of 70% by weight
• sample II 80% by weight
• part of the coating of the respective sample was scraped off, ground to a powder and analyzed by XRD.
• measured values for samples (sample 1a and sample 11a) which have been produced in a conventional manner ie with a heat treatment duration of 6 hours
• (W) and (Re) are both mixed crystal phases ((W) is a tungsten crystal with rhenium dissolved in it, analogously (Re) is a rhenium crystal with tungsten dissolved in it).
• Wo.sReo.s is an intermetallic phase and is also referred to as the s-phase in the phase diagram. The quantities given for the phases are in wt.%.
• Heat treatment duration as is typically used in the powder metallurgical processing of tungsten and rhenium.
• the proportion of ReßW is around 90 wt% in both samples, Sample I (70 wt% rhenium) and Sample II (80 wt% rhenium), while the proportion of Rez ⁇ N in the corresponding, conventionally prepared samples is 21.8 wt.% (Sample la) or 27.8 wt.% (Sample lla).
• a significantly higher thermal emission coefficient is also associated with the high proportion of ReßW.
• FIGS. 4a and 4b show X-ray diffractograms (XRD) of sample II (FIG. 4a) and sample IIa (FIG. 4b).
• XRD X-ray diffractograms
• intensity values are given as a function of the deflection angle 2Theta (range from 30 to 65 2Theta) and the measured reflections (peak values) of the phases present assigned.
• the proportion of ReBW predominates.
• Table 3 demonstrates the temperature resistance of the samples of the invention. Shown is the thermal emissivity reading as a function of the temperature at which the sample was heat stressed. The samples were annealed at this temperature for a period of one hour. Table 3: Temperature resistance
• the material withstands the high thermal stress, but the porous layer begins to sinter a little. Nevertheless, a high thermal emissivity is maintained even at this high temperature.
• the coating according to the invention thus withstands loads of 2000° C. and above and can therefore be used for heating filaments in MOCVD
• An alternative variant for producing the coating is based on physical vapor deposition.
• a tungsten plate was first coated with a conventional 100% tungsten slurry layer. This serves to increase the surface area.
• An approx. 4 ⁇ m thick layer with Re3W phase was sputtered onto this layer by means of a target which has approx. 98% Re3W phase.
• the resulting layer had approximately 75% wt.% rhenium. Since a part of
• a high-pressure discharge lamp 6 is shown schematically.
• a discharge arc is formed between the electrodes—a cathode 5 and an anode 4—during operation.
• the anode 4 is the high-temperature component 1 and is provided with a coating 3 according to the invention.
• the coating 3 allows the anode 4 to emit a higher thermal radiation output, which reduces its temperature and increases its service life.
• the cathode 5 or both the anode 4 and the cathode 5 can be provided with the coating 3 .
• the coating 3 according to the invention can also be used for other lamp types to increase a thermal emission level.
• FIG. 6 shows a heating conductor 7 made of a refractory metal in an exemplary arrangement as a floor heater of a high-temperature furnace.
• the heating conductor 7 is heated by direct current passage and heats the interior of the high-temperature furnace by emitting radiant heat.
• the heating conductor 7 forms the high-temperature component 1 and is provided with a coating 3 according to the invention to increase the degree of thermal emission.
• the coating 3 causes the latter to be able to provide a specified heat output at a lower temperature. This reduces creeping of the heating conductor 7 and increases the service life.
• FIG. 7 schematically shows a crucible 8 made of refractory metal.
• Crucibles made of refractory metal are used, for example, to melt aluminum oxide in the production of sapphire single crystals.
• the crucibles are placed in a high-temperature furnace and covered by heating conductors heated by radiant heat. The heat transfer takes place mainly via the outer surface of the crucible, which absorbs the radiant heat and passes it on to the material to be melted.
• the crucible 8 forms the high-temperature component 1 and is provided with a coating 3 according to the invention to increase a thermal
• the coating 3 when applied to a crucible 8 has the effect that a larger proportion of the heat given off by heating conductors is coupled into the crucible 8 . As a result, the crucible 8 reacts more quickly to heat input from heating conductors.
• the application of the coating 3 is in no way limited to the examples shown here.
• the coating 3 is generally advantageous for high-temperature components on which heat transfer is to take place by means of radiation.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Composite Materials (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Physical Vapour Deposition (AREA)
• Powder Metallurgy (AREA)
• Other Surface Treatments For Metallic Materials (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=78077496

Family Applications (1)

Country Status (6)

Citations (7)

Family Cites Families (7)

• 2020
  • 2020-07-31 AT ATGM50153/2020U patent/AT17391U1/de unknown
• 2021
  • 2021-07-20 EP EP21754894.0A patent/EP4188625A1/de active Pending
  • 2021-07-20 JP JP2023505418A patent/JP7749657B2/ja active Active
  • 2021-07-20 CN CN202180048289.2A patent/CN115776920B/zh active Active
  • 2021-07-20 WO PCT/AT2021/060254 patent/WO2022020869A1/de not_active Ceased
  • 2021-07-20 US US18/007,173 patent/US12227829B2/en active Active

Patent Citations (7)

Also Published As

Similar Documents

Legal Events