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WO1999038819A1 - Procede pour produire des poudres oxydiques a faible teneur en carbone et en hydrogene, leur utilisation, ainsi que systemes d'oxydes mixtes pour supraconducteurs a haute temperature, et supraconducteurs a haute temperature - Google Patents

Procede pour produire des poudres oxydiques a faible teneur en carbone et en hydrogene, leur utilisation, ainsi que systemes d'oxydes mixtes pour supraconducteurs a haute temperature, et supraconducteurs a haute temperature Download PDF

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Publication number
WO1999038819A1
WO1999038819A1 PCT/EP1999/000565 EP9900565W WO9938819A1 WO 1999038819 A1 WO1999038819 A1 WO 1999038819A1 EP 9900565 W EP9900565 W EP 9900565W WO 9938819 A1 WO9938819 A1 WO 9938819A1
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Prior art keywords
acid
ppmw
powder
reactor
temperature
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PCT/EP1999/000565
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German (de)
English (en)
Inventor
Joachim Bock
Michael BÄCKER
Dieter Sachse
Horst Hahn
Günther RIEDEL
Thomas Diehl
Original Assignee
Aventis Research & Technologies Gmbh & Co. Kg
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Priority claimed from DE19803447A external-priority patent/DE19803447A1/de
Priority claimed from DE19837548A external-priority patent/DE19837548A1/de
Application filed by Aventis Research & Technologies Gmbh & Co. Kg filed Critical Aventis Research & Technologies Gmbh & Co. Kg
Priority to AU24250/99A priority Critical patent/AU2425099A/en
Publication of WO1999038819A1 publication Critical patent/WO1999038819A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G29/00—Compounds of bismuth
    • C01G29/006—Compounds containing bismuth, with or without oxygen or hydrogen, and containing two or more other elements
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/01—Manufacture or treatment
    • H10N60/0268—Manufacture or treatment of devices comprising copper oxide
    • H10N60/0772—Processes including the use of non-gaseous precursors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/01—Manufacture or treatment
    • H10N60/0268—Manufacture or treatment of devices comprising copper oxide
    • H10N60/0801—Manufacture or treatment of filaments or composite wires
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/10—Solid density
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity

Definitions

  • the invention relates to a method for producing oxidic powders, in particular for caicinizing oxide precursors to form oxidic powders, and the use of these powders for the production of moldings and high-temperature superconductors.
  • the invention further relates to mixed oxides in the form of
  • Powders or moldings with a very low carbon content or with a very low hydrogen content which are suitable for the production of high-temperature superconductors, and corresponding high-temperature superconductors, in particular in the form of strips, wires or solid parts.
  • inorganic powdery material with high chemical purity, homogeneity, phase purity, defined phase composition and grain size is synthesized.
  • This material contains mixed oxides, which besides
  • Oxygen predominantly contain one or more alkaline earth metals, copper and one or more elements from the group bismuth, lead, yttrium, lanthanum, lanthanides and thallium and optionally further oxides.
  • This oxidic powder can either be solid with superconducting parts
  • Annealing to solid parts takes place in further thermal processes, in which the properties of the powder particles are also modified. In these processes, no volatile constituents may be released from the material that lead to bubble production. For this reason, for example, the residual carbon content of the powders and moldings should be as low as possible.
  • the low carbon content and, if possible, the low hydrogen content should be achieved during the production of the oxidic powder.
  • the oxidic powder for further processing into the end products should have a small grain size and high reactivity for the conversion into the desired superconducting phase, which takes place during the thermal treatment.
  • the oxidic powder used based on Bi, Pb, Sr, Ca cuprates with the so-called (Bi, Pb) -2212 phase should easily convert to the (Bi, Pb) -2223 phase during the thermal treatment.
  • a conventional method is that oxide precursors in chamber or
  • Tube furnaces can be caicinised as fillings in several steps. This method requires long treatments at high temperatures.
  • EP-A-0 369 117 describes a spray pyrolytic process in which a metal nitrate solution is sprayed into a calcination zone where it is brought into contact with a hot gas stream.
  • oxidic ceramic powders are also obtained by a spray pyrolytic process of metal nitrate solutions by pyrolyzing the nitrates in the presence of organic substances serving as fuel. Both methods are quite complex in terms of equipment. In addition, the resulting nitrous gases require special measures for reasons of occupational safety and environmental protection.
  • EP-A-0 573 804 describes oxide-ceramic superconductor materials with a carbon content in the range from 200 to 800 ppmw. This carbon content should be able to be set by prematurely stopping sales fires or in an additional annealing or melting treatment with a higher CO 2 content than air. Above all, there will be an additional multi-level sales fire recommended, the material should even be shredded between the individual stages, which is a very complex process.
  • the object of the present invention was to create a cost-effective method for caicinizing powdery, homogenized oxide precursors, in which oxidic powders with a low residual carbon content and / or a low residual hydrogen content are obtained at the lowest possible temperatures and short reaction times.
  • the object is achieved in that the powder particles of the oxide precursor are largely separated, are fed to an essentially vertical, tubular reactor, pass the reactor from top to bottom in countercurrent to a gas and are thermally decomposed in the process.
  • the object is achieved with a process for producing oxidic powders with a carbon content of ⁇ 200 ppmw and with a hydrogen content of ⁇ 150 ppmw with a composition which can result in a high-temperature superconductor from the powdery treatment
  • Oxide precursors which can be further processed into shaped bodies and possibly also into high-temperature sintered bodies, in which the powder particles of the oxide precursor are largely separated, are fed to an essentially vertical, tubular reactor, pass the reactor from top to bottom in countercurrent to a gas and be thermally decomposed in the process. 5
  • the object is achieved with a method for producing oxidic powders with a carbon content of ⁇ 200 ppmw and with a hydrogen content of ⁇ 150 ppmw with a composition which can result in a high-temperature superconductor during further treatment, and optionally to give moldings and possibly also high-temperature superconductors
  • Sintered bodies can be processed further, the oxidic powders or the moldings produced therefrom being treated with an acid which is added as an acid, in particular is added to the furnace atmosphere, or which is added as a thermally decomposable salt, the added or / and that in the thermal decomposition of the salt released acid to remove carbon or / and
  • the superconductor material with these carbon and hydrogen contents is preferably in the equilibrium state.
  • the oxide precursor is a mixture of compounds of several elements, selected from the group Mg, Ca, Sr, Ba, Sc, Y, La, lanthanides, Zr, Pt, Ag, Cu, Hg, Al, Tl, Pb, Bi and Nd, which can be present as acetates, carbonates, citrates, hydroxides, lactates, nitrates, oxalates, tatrates or mixtures thereof. If nitrates are used, they are only present in small proportions in mixtures.
  • a mixture of compounds of the elements Bi, EA and Cu is particularly preferred; (Bi, Pb), EA and Cu; Y, EA and Cu; (Y, SE), EA and Cu; Tl, EA and Cu; (Tl.Pb), EA and Cu; Ti, (Y, EA) and Cu; or Hg, EA and Cu, where EA means alkaline earth metal, in particular Ba, Ca, and / or Sr and SE rare earth metals. Oxalates, hydroxides and acetates or mixtures thereof are particularly preferred
  • Element groups used as an oxide precursor used as an oxide precursor.
  • the powdery, homogenized oxide precursor is preferably a coprecipitate powder.
  • This powder can be obtained, for example, by starting from a nitrate solution of the metals and by adding oxalic acid or a corresponding other acid to precipitate the metal salts which 6 then be spray dried into the coprecipitate powder.
  • the powdery, homogenized oxide precursor can also be produced in the dry state by mixing the corresponding salts and / or hydroxides.
  • the powdery oxide precursor preferably has a residual moisture content of ⁇ 1.5%.
  • the powder particles are largely separated so that they are fed to the reactor in fine distribution. This separation can take place, for example, in that the powder particles pass through a vibrating sieve. The separation can also be carried out by swirling in the gas stream.
  • a vibrating sieve it can be particularly useful to provide a stirring blade in the sieve at a small distance (for example 1 to 5 mm) from the sieve bottom to produce a mixing movement which ensures uniform metering into the reactor and prevents clogging of the sieve .
  • Mesh size of the sieve can be in the range from 20 to 400 ⁇ m, preferably in the range from 40 to 200 ⁇ m and in particular in the range from 63 to 125 ⁇ m.
  • the choice of the mesh size of the sieve depends on the desired particle size that is to be fed to the reactor, which will be discussed in more detail below.
  • this is achieved with the relatively short holding times and low temperatures just mentioned by using a negative pressure of 0.01-10 mbar, preferably 0.1-1 mbar.
  • the reactor is preferably tubular and arranged essentially vertically. Essentially vertical means that even small slopes, i.e. small angles to the normal are possible. However, it is particularly preferred to be vertical.
  • the reactor is preferably heated indirectly by means of an electric heater in the form of a plurality of fiber-insulated heating modules which surround the outside of the tube and each have separate temperature control devices.
  • the reactor is preferably made of a heat-resistant material, for example quartz glass, ceramic or metal.
  • the ratio of the heated length to the inside diameter of the reactor is generally in the range from 10 to 50: 1, preferably in the range from 15: 1 to 30: 1 and in particular in the range from 20: 1 to 30: 1.
  • the length of the reactor can be between 0.2 to about 10 m, preferably between 1 to 5 m.
  • the inside diameter of the reactor should not be too large.
  • an inner diameter is chosen to be not substantially more than 100 mm, preferably not more than 80 mm.
  • An increase in throughput is preferably achieved by using several tubular reactors which are arranged in the form of a bundle within the same heating system.
  • the number of reactors is limited by the fact that, based on their cross section, 8th
  • the same temperature should be present.
  • the temperature difference across the cross section should not be greater than + 1-2 K if possible, because otherwise the powder will not be homogeneously caicinated and different carbon contents can occur in the reaction product.
  • the powder particles of the oxide precursor are fed to the tubular reactor from above, in which they sink downward in countercurrent to a gas.
  • gases used can be nitrogen, oxygen, argon, their mixtures, air or a more oxygen-rich mixture with an N 2 / O 2 ratio of up to 10:90.
  • the gas preferably has an N 2 / O 2 -
  • Oxygen can also be used preferably.
  • the gas contains a sufficiently high proportion of oxygen towards the end of the calcination.
  • An oxygen partial pressure of the gas conducted in countercurrent to the reaction mixture, increasing from top to bottom in the tubular reactor, is therefore particularly preferred.
  • it is favorable to supply an oxygen-rich nitrogen-oxygen mixture or oxygen at the lower end of the tubular reactor and a mixture with a lower oxygen content, in particular air or nitrogen, in the central region of the reactor.
  • the gaseous decomposition products in particular CO 2
  • the amount of gas supplied should be selected in relation to the reactor diameter so that the resulting gas velocity, on the one hand, allows the gases which are produced in the decomposition reaction to be rapidly removed upward from the reactor 9
  • oxidic superconductor materials with particularly low carbon contents is also possible after a single pass through the preferably tubular reactor, if the subsequent post-calcination in pure oxygen e.g. in the range of about 12 h at 800 ° C, the phase setting e.g. in the range of about 3 h at 780 ° C and the final annealing of the compacts made from this powder e.g. in the range of about 5 h at 740 ° C. in a nitrogen atmosphere with an oxygen content of 0.1-3%, preferably 1%.
  • the repeated annealing of the moldings has the advantage that carbon accumulation that occurs through handling or mechanical reworking of the molded parts is compensated for again. This means that the carbon content can be reduced to values ⁇ 100 ppm (50-80 ppm), that if properly packaged in synthetic air or another dry air
  • the thermal decomposition of the oxide precursor takes place in the reactor at normal pressure and temperatures in the range from 400 ° C. to 900 ° C., preferably in the range from 550 ° C. to 900 ° C. and in particular in the range from 650 ° C. to 900 ° C.
  • the heated area of the reactor can be a zone with a uniform temperature, especially if the calcined powder particles are subjected to a post-calcination.
  • the calcination is generally carried out at a temperature in the range from 550 ° C to 900 ° C, preferably 550 ° C to 830 ° C.
  • Post-calcination can be carried out continuously in a rotary kiln, in a fluidized bed 10 or in batch operation as a bed in open containers in a gas stream in order to form the superconducting mixed oxide phases at temperatures above 77 K.
  • the heated zone in the reactor can be shorter and air or oxygen-enriched air can be supplied to the reactor as gas in order to achieve economical operation.
  • agglomeration is desirable in order to achieve continuous transport or fluidizability. The agglomeration is advantageously achieved in that the
  • Powder particles of the oxide precursor are separated through a coarser sieve before they are fed to the reactor.
  • mesh sizes of the sieve are selected which are in the range from 200 to 400 ⁇ m.
  • a sieve with a small mesh size is preferably used in the method according to the invention.
  • the heated area of the reactor has two or more zones with different temperatures.
  • a lower temperature is selected for the upper or uppermost zone of the reactor, which the powder particles pass first, than for the lower or the lowest zone.
  • the temperature in the upper part of the tubular reactor can range from 400 ° C to 700 ° C and the temperature in the lower part of the reactor can range from 750 ° C to 900 ° C.
  • oxide precursors are used which decompose in an exothermic reaction even at relatively low temperatures.
  • the decomposition reaction of bismuth oxalate begins at 236 ° C.
  • the first heating zone through which the powder particles pass is therefore comparatively low at around 650 ° C 11 set. Overheating due to the heat released during oxalate decomposition is avoided, which would lead to undesired sintering of the powder particles into large and hard agglomerates.
  • the lower or lowest heating zone is set to a higher temperature in order to lower the carbon content in the powder particles and to initiate the formation of superconducting mixed oxide phases, which, however, usually only takes place to a sufficient extent in the subsequent thermal treatment.
  • the powder particles of the oxide precursor fed to the reactor preferably have a size of ⁇ 20 ⁇ m, in particular ⁇ 15 ⁇ m and particularly preferably ⁇ 10 ⁇ m (measured with laser light diffraction, Mastersizer from Malvern Instruments GmbH). This also applies if the heated area of the reactor is a zone with a uniform temperature, unless, as stated above, post-calcination in the rotary kiln or in the fluidized bed is provided.
  • the small particle size and the use of oxygen as a gas greatly reduce the carbon content without significantly extending the heated reactor area. This allows the conventional
  • the upper zone with a lower temperature it is possible for the upper zone with a lower temperature to be a lower-oxygen gas or nitrogen and the lower zone for an oxygen-rich one
  • the inventive method works continuously and has the advantage that with short treatment times of a few seconds, a decomposition of the
  • the agglomerates of the oxidic powder have a small average grain size, and the proportion of agglomerates> 40 ⁇ m, which is 20 to 30% in conventional processes, and the proportion of hard agglomerates are very small.
  • Another advantage of the method according to the invention is the higher reactivity of the oxidic powder produced for the conversion into the superconducting target phase, for example (Bi, Pb) -2223.
  • the carbon content of the oxidic powder is reduced to ⁇ 0.5% or even ⁇ 0.1% in one pass.
  • the thermal phase adjustment process can follow immediately, which is preferably carried out on moldings to which the oxidic powder is pressed.
  • the process according to the invention also has the advantage that metallic impurities on Fe, Cr and Ni, which negatively influence the superconducting properties, are avoided.
  • a shaped body can be produced from the oxidic powder, optionally without an additional grinding process, for example by isostatic pressing, and can be further processed in various ways by thermal treatment. Subsequent sintering can be used to produce a solid superconducting part, or the material for the production of superconducting wires and tapes can be obtained through a special annealing process with a defined oxygen partial pressure. can be used.
  • a homogeneous mixture of oxalates for example of the elements Bi, Pb, Sr, Ca and
  • the formation of the superconducting phase (Bi, Pb) -2212 with a critical temperature of 92 K can then already begin.
  • this phase is mainly obtained only in subsequent thermal steps, for example those described above
  • Post-calcination processes and thermal treatments such as sintering and special tempering processes.
  • the recalcination process can be omitted if the process is preferred.
  • the formation of the superconducting phase (Bi, Pb) -2223 with a critical temperature of 1 10 K represents the target phase in the solid part and wire production. It is only formed during the sintering to the solid part or the thermomechanical treatment of the wire production.
  • Moldings are treated with an acid which is added as an acid, in particular is added to the furnace atmosphere, or which is added as a thermally decomposable salt, the acid added or / and released during the thermal decomposition of the salt to remove carbon and / or hydrogen contributes.
  • an acid which is added as an acid, in particular is added to the furnace atmosphere, or which is added as a thermally decomposable salt, the acid added or / and released during the thermal decomposition of the salt to remove carbon and / or hydrogen contributes.
  • the oxidic powders or the moldings produced therefrom can be treated with organic acids or / and mineral acids which have a greater acid strength than carbonic acid, in particular with formic acid, acetic acid, sulfuric acid and / or nitric acid. This procedure can be used
  • the oxidic powders or the shaped bodies produced therefrom can be treated with an acid, which is a thermally decomposable salts of acids which are relatively large Have acid strength as carbonic acid, are added, in particular ammonium, ammonium hydrogen or metal hydrogen salts or in particular salts of formic acid, acetic acid, sulfuric acid or nitric acid, with the metallic or semimetallic elements present in the superconducting material being preferred as the metal. Due to the thermal decomposition, this process requires a minimum temperature of usually 150 ° C and is particularly suitable for moldings.
  • the acid can be added in solid, liquid, dissolved or gaseous form or the salt in solid, dissolved or liquid form.
  • the chemical reaction with the acid can in principle take place at room temperature or at low to very high temperatures, in particular when heating to a higher temperature, it being possible for the chemical reaction to be essentially completed before the end temperature is reached.
  • Preferred is the addition in the form of a gaseous acid when acting on a powder, in particular in the form of a powder bed, preferably at 50 to 200 ° C, or the addition in the form of a thermally decomposable salt in solid form when acting on one
  • Shaped body preferably at 150 to 500 ° C. 15
  • an alkaline earth metal sulfate can be formed in the powder or shaped body if sulfate is present, the alkaline earth metal sulfate being homogeneously finely dispersed in the powder or in the shaped body.
  • the particles of this sulfate, in particular sulfates of Ba, Ca or / and Sr, are not decomposed even during the later sintering and / or thermal aftertreatment and act as
  • Crystallization nuclei as structure-modifying components that have a positive influence on microstructure formation, and possibly as pinning components.
  • the present invention also relates to a mixed oxide, in particular in the form of a powder or a shaped body, with a carbon content ⁇ 200 ppmw, in particular ⁇ 150 ppmw, particularly preferably ⁇ 100 ppmw or with a hydrogen content ⁇ 150 ppmw, in particular ⁇ 100 ppmw preferably ⁇ 60 ppmw or ⁇ 50 ppmw.
  • a mixed oxide in particular in the form of a powder or a shaped body, with a carbon content ⁇ 200 ppmw, in particular ⁇ 150 ppmw, particularly preferably ⁇ 100 ppmw or with a hydrogen content ⁇ 150 ppmw, in particular ⁇ 100 ppmw preferably ⁇ 60 ppmw or ⁇ 50 ppmw.
  • Such mixed oxides are either after two passes through the reactor with two or more temperature zones and oxygen as a gas at least in the lower region of the
  • Mixed oxide means both the powder and the powder formed into a shaped body.
  • the thermal treatment comprises annealing the powder or the shaped body at, for example, 770 ° C. in a stream of nitrogen, optionally mixed with oxygen, for three hours.
  • the present invention furthermore relates to a high-temperature superconductor with a carbon content of ⁇ 100 ppmw, in particular ⁇ 80 ppmw, particularly preferably ⁇ 50 ppmw or else a high-temperature superconductor with a hydrogen content ⁇ 100 ppmw, in particular ⁇ 60 ppmw, particularly preferably ⁇ 40 ppmw.
  • a high-temperature superconductor with a carbon content of ⁇ 100 ppmw in particular ⁇ 80 ppmw, particularly preferably ⁇ 50 ppmw or else a high-temperature superconductor with a hydrogen content ⁇ 100 ppmw, in particular ⁇ 60 ppmw, particularly preferably ⁇ 40 ppmw.
  • Such low levels of carbon or hydrogen have been sought after for many years in high-temperature superconductor materials and have been
  • Hydrogen is lower than with the mixed oxides used, since any thermal treatment leads to a reduction as long as these traces are in the form of easily decomposable compounds.
  • the compounds of these elements which are difficult to decompose in the usual temperature range up to about 800 ° C or up to about 850 ° C under the selected atmospheric conditions, e.g. However, strontium carbonate can only be removed with acids using a chemical process.
  • the oxidic powders or molded articles produced therefrom by the process according to the invention are for the manufacture of high-temperature superconducting wires, strips, rods, tubes, hollow and solid bodies, in particular for the manufacture of high-voltage cables, power lines, transformers, windings, magnets, power supplies, electric motors , Energy storage, current limiters or magnetic bearings can be used.
  • the figure shows a schematic illustration of the tubular reactor and the associated device parts for the process according to the invention.
  • the oxide precursor is from the storage container 1 via a powder flap 2 and
  • the sieve 5 is with 17
  • a stirrer 6 for which a motor 7 is provided.
  • the impeller of the stirrer 6 is located a short distance above the sieve bottom 8.
  • the sieve 5 is set in vibration by a pneumatic vibrator 9.
  • the powder particles of the oxide precursor are separated as they pass through the sieve 5. They fall evenly distributed over the reactor cross section into the open tubular reactor 10. In its simplest embodiment, this has a zone heated by an electric heater 11 for which control electronics 12 are provided. Gas is supplied to the reactor 10 from below via lines 13 and 14. The line 13 is provided for the oxygen supply and the line 14 for the nitrogen supply. Any ratio of oxygen to nitrogen in the gas supplied to the reactor 10 can be set via control electronics 15, which act on the valves 16 and 17.
  • the powder particles sink in the reactor in countercurrent to the gas introduced from below and are thermally decomposed in the heated zone of the reactor.
  • the oxidic powder falls into the collecting container 18 arranged under the reactor 10.
  • the speed of the gas flow can also be regulated via the valves 16 and 17. It is preferably set so that no powder or a maximum of 1% of the powder is discharged upwards.
  • the top part of the reactor 10 can be funnel-shaped (not shown in the figure), preferably by a factor of 1.5 to 3. This reduces the gas velocity in this area.
  • the exhaust gas flow which is predominantly passed to the side of the screen, can be passed through a Memtic particle filter, not shown, in order to separate out emerging powder particles.
  • this filter can be omitted if the exhaust gas is cleaned in a wet scrubber. This is particularly recommended if the
  • Reactor is operated in combination with a spray dryer in which a 18th
  • Suspension with wet homogenized oxide precursors is spray dried and this is already equipped with a wet washer.
  • the exhaust gas stream from the reactor can then be fed to the latter.
  • a wet washer is particularly recommended for lead-containing oxide precursors.
  • the product was placed on a sieve with a mesh size of 150 ⁇ m vibrating by means of a pneumatic vibrator and introduced into the reactor in an amount of 300 g / h by additional stirring of the feed material.
  • Reactor material quartz glass Reactor geometry: heated length: 1, 50 m,
  • Second heating zone temperature 650 ° C
  • Residual carbon content of the calcine after one reactor run 2.8% (measured by means of thermal oxidation and infrared detector: device from Elementar High TOC).
  • Contaminant content of the calcine 80 ppmw Fe, 20 ppmw Ni, 30 ppmw Cr (measured by ICP / OES). This did not represent an increase in the content of Fe, Ni and Cr, taking into account the loss of ignition during the calcination, compared to the starting products.
  • the sum of the metallic impurities also remained constant, taking into account the loss of ignition during the calcination.
  • the mean agglomerate grain size was 20 ⁇ m (dispersion in silicone oil with 60 s ultrasound treatment; laser granulometer, device type CILAS 715).
  • the carbon content was further reduced by annealing in the powder bed for 12 hours at 800 ° C. in an oxygen stream.
  • the powder was sieved ⁇ 40 ⁇ m and pressed at a pressure of 2000 bar.
  • the compacts were annealed for 120 hours at 825 ° C. in a tube furnace in a gas stream (250 l / h) consisting of nitrogen and 1% oxygen, the conversion to the (Bi, Pb) -2223 phase being carried out.
  • cylinders with a diameter of 15 mm and a length of 100 mm were produced from the powder sieved ⁇ 40 ⁇ m using isostatic pressing at 2000 bar using the dry die process. These were used to produce a phase composition of approximately 85% orthorhombic (Bi, Pb) -2212 phase as well as (Sr, Ca) cuprates and
  • Method for producing a mono- and / or multifilament strip conductor with a silver sheath and powder core can be processed further.
  • Example 2 The procedure was as in Example 1, but with the following differences:
  • the product was placed on a sieve with a mesh size of 125 ⁇ m, which vibrated by means of a pneumatic oscillator, and was introduced into the reactor in an amount of 200 g / h with additional stirring of the feed material.
  • the residual carbon content after one reactor run was 0.6%.
  • the metallic impurities corresponded to those of Example 1.
  • the average agglomerate grain size was 3 ⁇ m (dispersion in silicone oil at 60 seconds
  • Example 1 wherein the carbon content after the oxygen annealing step was 0.05%.
  • the carbon content of the sintered bodies was 0.004% and that of the shaped bodies for the wire production was 0.008%.
  • Example 2 The powder of Example 2 was placed on a sieve vibrating by means of a pneumatic vibrator with a mesh size of 50 ⁇ m and introduced into the reactor in an amount of 100 g / h with additional stirring of the feed material.
  • the residual carbon content after a reactor run was 0.08%, the metallic impurities corresponded to those of Example 1.
  • the average agglomerate grain size was 8 ⁇ m (dispersion in silicone oil with 60 s ultrasound treatment; laser granulometer, device type GLAS 715). These agglomerates, like the powders produced in Example 1, were easily destructible. Hard agglomerates were not contained in this powder. 22
  • the oxygen annealing step described in Examples 1 and 2 could be dispensed with, and the powder could be pressed to the shaped body after sieving on a 40 ⁇ m sieve.
  • this powder was significantly improved compared to the material conventionally processed in the powder filling, so that a mold with a diameter of 15 mm and a length of 120 mm could be filled uniformly without additional aids such as pressing aids or vibration. As in the case of sample preparation according to Examples 1 and 2, this prevented the eaicinated powders from absorbing moisture from the ambient atmosphere before processing.
  • the carbon content of the sintered bodies was 0.006% and that of the shaped bodies for the wire production was 0.012%.
  • Example 4 400 g of an oxide powder according to Example 2 eaicinated in a vertical reactor were placed in a silver boat in the middle of a gas-tight horizontal tube furnace.
  • 50 ml of conc. Nitric acid submitted.
  • the tube furnace was then heated to 150 ° C. with a flowing nitrogen atmosphere (20 l / min).
  • the nitric acid slowly evaporated and was passed from the inert gas stream over the powder, where the reaction of the residual hydroxides and carbonates to the corresponding nitrates took place.
  • the tube furnace was slowly heated to the annealing temperature of 800 ° C. and held at this temperature for 60 h, during which the nitrates formed were decomposed to form metal oxides and nitrogen oxides.
  • the powder had a residual carbon content of 50 ppmw and a residual hydrogen content of 40 ppmw.
  • Example 5 The spray-dried powder mixture from Example 1 was used in Ag glow boats
  • the residual carbon content after calcination was 3.5%, the metallic impurities correspond to example 1.
  • the average agglomerate grain size was 30 ⁇ m (dispersion in silicone oil with 60 s ultrasonic treatment:
  • Comparative Example 1 The spray-dried powder mixture from Example 1 was used in Ag glow boats
  • the residual carbon content after the calcination was 3.5%, the metallic impurities corresponded to example 1.
  • the average agglomerate grain size was 30 ⁇ m (dispersion in silicone oil with 60 s ultrasound treatment:
  • the carbon content was further reduced by annealing in the powder bed for 18 hours at 800 ° C. in an oxygen stream.
  • the carbon content was reduced to 0.1%.
  • the powder was sieved to a particle size ⁇ 40 ⁇ m and pressed at a pressure of 2000 bar.
  • the compacts were at 120 h 25th
  • Step temperature T c 1 10 ° C;
  • Shaped body production for wires Since the powders had to be ground before pressing because of the hard agglomerates that were too large for the wire production, the flowability was significantly poorer than that of the powders of Examples 1 to 3.
  • the powder which was dry-ground using a vibrating mill and sieved again to a particle size of ⁇ 40 ⁇ m, was used for isostatic pressing
  • Cylinder with a diameter of 15 mm and a length of 100 mm manufactured by the dry matrix process were annealed for three hours at 770 ° C. in nitrogen with a proportion of 1% oxygen to produce a phase composition of approximately 85% orthorhombic (Bi, Pb) -2212 phase and (Sr, Ca) cuprates and CuO.
  • the carbon content was reduced to 0.035
  • the residual carbon content was then 75 ppmw.

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  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
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  • Inorganic Chemistry (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Abstract

L'invention concerne un procédé pour produire des poudres oxydiques présentant une teneur en carbone < 200 ppmw, une teneur en hydrogène < 150 ppmw et une composition pouvant donner un supraconducteur à haute température après traitement ultérieur. Ces poudres oxydiques sont constituées de précurseurs d'oxydes pulvérulents pouvant être transformés en corps moulés et éventuellement également en corps frittés supraconducteurs à haute température. Les particules de poudre du précurseur d'oxyde sont amplement dispersées, acheminées à un réacteur tubulaire sensiblement vertical, passent à travers ce dernier de haut en bas à l'encontre du flux d'un gaz et sont thermiquement décomposées au cours de ce processus. En variante, la poudre oxydique ou bien les corps moulés réalisés à partir de celle-ci sont traités avec un acide qui est ajouté sous forme d'acide, notamment à l'atmosphère protectrice, ou bien sous forme de sel décomposable thermiquement. L'acide ajouté et/ou l'acide libéré lors de la décomposition thermique du sel contribuent à l'élimination du carbone et/ou de l'hydrogène. L'invention concerne également les systèmes d'oxydes mixtes et les supraconducteurs à haute température correspondants.
PCT/EP1999/000565 1998-01-30 1999-01-28 Procede pour produire des poudres oxydiques a faible teneur en carbone et en hydrogene, leur utilisation, ainsi que systemes d'oxydes mixtes pour supraconducteurs a haute temperature, et supraconducteurs a haute temperature WO1999038819A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU24250/99A AU2425099A (en) 1998-01-30 1999-01-28 Method for producing oxidic powders with a low carbon and hydrogen content and their use as well as mixed oxides for high-temperature superconductors and high-temperature superconductors

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE19803447A DE19803447A1 (de) 1998-01-30 1998-01-30 Verfahren zur Herstellung von Precursormaterial für die Produktion von Hochtemperatursupraleiter-Drähten
DE19803447.4 1998-01-30
DE19837548.4 1998-08-19
DE19837548A DE19837548A1 (de) 1998-08-19 1998-08-19 Verfahren zum Calcinieren von Oxidvorprodukten zu oxidischen Pulvern, deren Verwendung sowie Mischoxide für Hochtemperatursupraleiter und Hochtemperatursupraleiter

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WO1999038819A1 true WO1999038819A1 (fr) 1999-08-05

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002072471A3 (fr) * 2001-03-13 2003-10-02 Merck Patent Gmbh Procede de production de poudres d'oxyde metallique multicomposants dans un reacteur pulse
EP1035592A3 (fr) * 1999-03-05 2004-12-01 International Superconductivity Technology Center Supraconducteur d'oxyde et procédé de fabrication
CN104713755A (zh) * 2015-01-12 2015-06-17 苏州赛力菲陶纤有限公司 一种复丝拉伸试验样品制备装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991006510A1 (fr) * 1989-11-07 1991-05-16 Pierluigi Villa Procede de preparation de supraconducteurs du type a oxyde et precurseurs obtenus a cet effet
WO1992006037A1 (fr) * 1990-10-01 1992-04-16 Sri International Nitrates ou oxydes inorganiques exempts de carbonate et procede de production
EP0611737A1 (fr) * 1993-02-17 1994-08-24 Hoechst Aktiengesellschaft Procédé de préparation d'un matériau précurseur de supraconducteur à haute température pour la méthode "oxide-powder-in-tube" (OPIT)

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991006510A1 (fr) * 1989-11-07 1991-05-16 Pierluigi Villa Procede de preparation de supraconducteurs du type a oxyde et precurseurs obtenus a cet effet
WO1992006037A1 (fr) * 1990-10-01 1992-04-16 Sri International Nitrates ou oxydes inorganiques exempts de carbonate et procede de production
EP0611737A1 (fr) * 1993-02-17 1994-08-24 Hoechst Aktiengesellschaft Procédé de préparation d'un matériau précurseur de supraconducteur à haute température pour la méthode "oxide-powder-in-tube" (OPIT)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1035592A3 (fr) * 1999-03-05 2004-12-01 International Superconductivity Technology Center Supraconducteur d'oxyde et procédé de fabrication
WO2002072471A3 (fr) * 2001-03-13 2003-10-02 Merck Patent Gmbh Procede de production de poudres d'oxyde metallique multicomposants dans un reacteur pulse
US7358212B2 (en) 2001-03-13 2008-04-15 Merck Patent Gmbh Method for producing multinary metal oxide powders in a pulsed reactor
CN104713755A (zh) * 2015-01-12 2015-06-17 苏州赛力菲陶纤有限公司 一种复丝拉伸试验样品制备装置

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