JPS63308810A - Superconductor which can be taken up by winding and manufacture of the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a superconductor, particularly in the rollable manner, for electrical cables and conductors, consisting of an inner superconducting core and an outer metal sleeve, and a method of manufacturing the same.

It is already known how to make superconductors of the type described at the beginning of the flexible properties by first applying a superconducting layer on a continuous metal support by spraying the metal in the form of a plasma. It is being The laminated support body is then covered with a longitudinally running metal strip, the slit tube thus formed is then welded longitudinally, and finally the outer diameter of the minimally superconducting layer is welded. The diameter is reduced (see DE 21088635). In this case, the intermetallic mixture Nb3Sn, which has a relatively low transition temperature, is used as the superconducting layer. Therefore, conductors made based on this compound have high equipment and cooling costs and have not been valued for their economic versatility compared to conventional energy transfer systems.

During that time, superconducting compounds that can reach superconductivity of 100 and more have become known, but these compounds have not yet been approved for their technical use.

Based on these known techniques, the problem underlying the present invention is to solve the problem of high transition temperature (sprung temperature).
The object of the present invention is to provide a superconductor which can be manufactured in an economically acceptable manner by a continuous manufacturing method and can be wound.

The above object is achieved according to the invention in that the core consists of pulverulent or granular particles of mixed oxides or contains mainly such mixed oxides.

Mixed oxides such as those mentioned above - also referred to in the literature as ceramic materials - are used in corresponding purity and treated to give them a superconductivity of 100 or more. This high transition temperature allows the use of liquid nitrogen as the coolant itself, and allows for significant improvements in economy over the previously required helium-cooling. Confinement of the mixed oxide within a metal sleeve ensures the production of superconductors in almost unlimited length.

The sleeve itself, which is made of copper material, for example, also serves as a mechanical support in the connection or connection position, and can also be used as a normal conductor in the event of a failure, for example in the coolant supply.

In carrying out the invention, it is advantageous to compress the particles forming the mixed oxide core into a consistently continuous continuum. This shaping allows for a uniform geometry and compactness of the core, which contributes to reduced electrical resistance in the essentially superconducting state. The monolithic structure of the continuum of mixed oxide particles is particularly advantageous for the production and for the mechanical stability of the superconductor. This can be done, for example, by adding a suitable binder to the mixed oxide or by placing the particles, for example on a support.
This can also be achieved, for example, by arranging it on the heart continuum.

Furthermore, it has proven advantageous when carrying out the invention if the mixed oxides, that is to say the so-called ceramic materials, contain copper, lead or bismuth. As another composition of the superconductor according to the present invention, at least one of the elements of Groups I and II of the periodic table is important. Research has confirmed that strontium (Sr) and barium (Ba), especially strontium (Sr) and barium (Ba) among group II elements of the periodic table, and combinations with group II elements, such as yttrium (Y) and lanthanum (La), already exhibit high transition temperatures. There is.

The use of mixed oxides as superconductors that actually have high transition temperatures is important for the present invention. The invention therefore consists in constructing a suitable method for making such a conductor, which can advantageously be made to any length and can be wound. For example, a longitudinally extending metal strip is formed into a tubular sleeve, and the mixed oxide particles are placed inside the metal strip. Subsequently, the edges of the metal strip are tightly and tightly closed, for example by welding or brazing, and the cross section of the tube thus formed is reduced in diameter.
do. In this case, it is advantageous to reduce the diameter of this cross section to such an extent that the powdery or granular particles of the mixed oxide are mechanically compressed during the reduction. It is advantageous to heat-treat the mixed oxide before, during or after coating the particles into the superconducting electrical conductor.

Another embodiment of the production of the superconductor according to the invention is to continuously compress the mixed oxide particles by pressing or extrusion into a continuum, which is then continuously formed into a tube. The edges of the metal strips are welded together. The dense sleeve is then reduced in diameter and formed into a continuous body, with the compacted continuous body being subjected to a temperature treatment before, during or after the coating. However, unlike this method, it is also possible to compress the continuous body and press-form the periphery seamlessly with a metal sleeve using a press, and otherwise perform the same method.

Another advantageous embodiment according to the invention for producing the superconductor is to press or extrude the particles of the mixed oxide into a continuous body and to subsequently subject this continuous body to a temperature treatment. The continuous body treated in this way is subsequently formed into a powder or granules, which powder or granules are loaded into the metal strip during the shaping of the metal strip into a tube. After welding the edges, the tube body is reduced in diameter and compressed again into a continuous body. This method provides favorable conditions for forming uniform geometries of superconductors made of ceramic materials (mixed oxides) and thus also for obtaining high transition temperatures. In this way, the process is further optimized by treating the mixed oxide in a milling step, with one or more simultaneous heat treatments, until it passes into the continuum form.

In this case, the temperature treatment before, during or after coating the superconducting continuum is in the temperature range between 850°C and 1650°C, in particular at 100°C.
℃ and 1500℃. If a heat treatment is carried out during or after the coating, a material with a correspondingly high melting temperature is selected as the sleeve surrounding the superconducting core.

In carrying out the invention, it is advantageous for the sleeve to consist of a metal or metal alloy that is permeable to oxygen. This configuration is useful when the mixed oxide has to be subjected to a temperature treatment step in the presence of oxygen for the purpose of obtaining superconducting potential, and when the mixed oxide is already exposed to the outside in a metal sleeve for manufacturing technology reasons. This is important when the data must be encapsulated. For example, it is suitable for the invention to use silver or silver alloys.

In this case, the production involves, for example, shaping a longitudinally running eyeband into a tubular sleeve and applying particles of the mixed oxide on the inner surface of this eyeband.

Subsequently, the edges of the ribbon are tightly and tightly closed, for example by welding or brazing, and the diameter of the tube thus formed is reduced. In this case, it is advantageous to carry out the cross-sectional diameter reduction to such an extent that the powdered or granular particles of the mixed oxide are mechanically compressed during the diameter reduction. It is advantageous to subject the mixed oxide to a temperature treatment before, during or after coating the particles with the superconducting electrical conductor. This temperature treatment, for example, an annealing step at 900° C., is performed in an oxygen atmosphere. This oxygen atmosphere ensures that the sleeve made of silver used according to the invention, for example, ensures oxygen diffusion with respect to the compressed mixed oxide particles.

According to another embodiment of the production of the superconductor according to the invention, the mixed oxide particles are continuously compressed by pressing or extrusion into a continuum, which continuum is subsequently continuously formed into a tube. The edges of the strips are welded together.

This closed metal sleeve is reduced in diameter and formed into a continuous body, with temperature treatment of this continuous body under the action of oxygen before, during or after coating the compressed continuous body. It will be done.

In contrast to this method, it is also possible, according to the invention, to compress the continuous body and then press around it with an oxygen-permeable metal sleeve to form it seamlessly, and the other process steps to be carried out in the same way. If the particles of the mixed oxide are formed into a continuous body by pressing or extrusion and subsequently subjected to temperature treatment, the treated continuous body is subsequently formed into a powder or granules, which powders or granules can be shaped into eyelids, for example. It is loaded into the tube while the body is being formed into a tube, and after welding the edges of the eyeband, the tube is again reduced in diameter and compressed into a continuous body.

The present invention will be explained with reference to FIGS. 1 and 2 attached below.

From a strip storage 2, which is supported on a winding table l, metal strips 3, for example eye strips, are fed via a deflection device 4 to a machine 5, optionally in the form of a strip cleaning station. In the area of this machine, the metal strip 3 is formed into a tubular shape 6 by means of forming tools (not shown) which are known per se, for example offset rollers or rolls. Mixed oxide 8 in powder form is loaded into this tube 6, which is still open at the top, by means of a feeding device 7. This powder is, for example, La-5r-
Cu-0+Ba-Pb-B i -0, Ba-La-C
It is produced by processing a continuous body formed by pressing and heat treatment from a mixed oxide based on u-0, Y-Ba-Cu-0 or similar materials into powder form. Further, while passing through the machine 5, the edge of the strip of the tube body 6 is tightly welded by a welding device 9, and while the tube body 6 passes through the diameter adjusting tool 10, its cross section is first reduced in diameter. The cross-section of the tube 6 filled with or containing the mixed oxide 8 in one or more stages is then calibrated by another diameter adjusting device 11.
The diameter of the particles of mixed oxide 8 present therein is reduced until they are sufficiently compressed. In some cases, this is followed by
A heat treatment, for example in the form of an annealing step, is carried out again.

As a result of this method, FIG. 2 shows a cross-section of a superconductor according to the invention, enlarged compared to FIG. 1. In this superconductor, a core of mixed oxide 8 is closely covered by a metal tube 6.

In this case, the tube body 6 is made of silver or is closely surrounded by another oxygen-permeable material or a corresponding alloy.

[Brief explanation of the drawing]

FIG. 1 is an overall view of an apparatus for producing a superconductor according to the present invention, and FIG. 2 is an enlarged sectional view of the superconductor itself according to the present invention. The symbols in the figure are as follows: 1... Winding table, 2... Strip storage section, 3... Metal strip, 4... Turning device, 5... Machine, 6...
Pipe body, 7... Feeding device, 8... Mixed oxide, 9...
・Welding equipment, 10.11...caliber adjustment tool

Claims (1)

[Claims] 1. Superconductors for electrical cables and conductors consisting of an inner superconducting core and an outer metal sleeve, especially in the form of a rollable material, in which the core is a mixed oxide powder. The above-mentioned superconductor is characterized in that it consists of shaped or granular particles, or that it mainly contains such mixed oxides. 2. The superconductor of claim 1, wherein the particles forming the mixed oxide core are compacted as a coherent continuum. 3. The superconductor according to claim 2, wherein the continuum of mixed oxide particles has a monolithic structure. 4. The superconductor according to claim 1, wherein the mixed oxide contains at least one of the following elements: copper, lead, or bismuth. 5. The superconductor according to any one of claims 1 to 3, wherein the mixed oxide contains at least one element of Groups II and/or III of the Periodic Table. 6. Superconductor according to claim 3, in which a lanthanide, in particular lanthanum itself, is used, consisting of a mixed oxide with an element of group III of the periodic table. 7. The superconductor according to any one of claims 1 to 6, wherein the sleeve is made of an oxygen permeable metal or alloy. 8. The superconductor according to claim 7, wherein the sleeve is made of silver or a silver alloy. 9. A method for making superconductors in which a longitudinally running metal strip, optionally made of an oxygen-permeable metal, is formed into a tubular sleeve, and a mixed oxide layer is coated on the inner surface of the metal strip. A method for producing a superconductor, characterized in that the particles are piled up and the edges of the metal strip are subsequently closed tightly and the cross section of the tube thus formed is reduced. 10. The method according to claim 9, wherein mechanical compaction of the mixed oxide powder or granular particles is carried out together with the cross-sectional reduction. 11. Process according to claim 9, characterized in that before, during or after coating the mixed oxide particles, the particles are subjected to a temperature treatment, optionally under the action of oxygen. 12. Particles of mixed oxide are first compression-molded continuously into a continuous body by pressing or extrusion molding, and this continuous body is then covered with a thin, longitudinally continuous metal strip formed into a tube. , the edges of this metal strip are welded together, and finally the dense sleeve is reduced in diameter and formed into a continuous body,
12. The method as claimed in claim 9, wherein the compacted continuous body is subjected to a temperature treatment, optionally under the action of oxygen, before, during or after the coating. 13. The mixed oxide particles are first continuously compressed into a continuous body by pressing or extrusion, and this continuous body is subsequently pressed and seamlessly surrounded by a dense metal sleeve, in this case overmolding. 13. The method as claimed in claim 9, further comprising carrying out a temperature treatment of the compressed continuum before, during or after , optionally under the action of oxygen. 14. The method according to claim 12 or 13, wherein the continuous body made by pressing or extrusion molding is formed into an integral structure. 15. A method according to any one of claims 12 to 14, characterized in that the mixed oxide particles are arranged on a core continuum. 16. Forming the particles of the mixed oxide into a continuous body by pressing or extrusion, subjecting this continuous body to temperature treatment, optionally under the action of oxygen, and subsequently converting it into powder or granule form;
Claim 9: The powder or granules are loaded into a metal strip while the metal strip is being formed to form a tube, and after welding the edges of the strip, the tube is compressed and reduced in diameter to form a continuous body. from 1
The method described in any one of 5. 17. Process according to claim 16, characterized in that the mixed oxide is subjected to a grinding step with one or more temperature treatments, optionally simultaneously, until it is transformed into a continuum shape. 18. Process according to any one of claims 9 to 17, characterized in that the temperature treatment is carried out in a temperature range between 850°C and 1650°C, in particular at a temperature between 1000°C and 1500°C.