JPH05101722A - Manufacture of multi-conductor ceramics superconductor - Google Patents

Abstract

PURPOSE:To obtain a long size multi-conductor ceramics supirconductor, which can be applied to a magnet or the like, by winding multiple compound sheets made of the ceramics raw material and a metal member spirally, and covering it with metal, and performing reduction processing and heat treatment. CONSTITUTION:Ceramics raw material as the raw material of a superconductor is filled in a metal pipe, and reduction processing is performed, and finally, rolling is performed to form a compound tape. Next, this tape wire material 3 or 4 is wound around of a metal pipe or a round bar 5 spirally so that they are not overlapped with each other and that a clearance is not generated, and it is inserted into the metal pipe again to form a compound billet. Reduction processing such as extracting, swaging, rolling is performed to the billet to obtain a multi-conductor ceramics superconductor. Since the superconductor is arranged spirally inside thereof and covered with metal, a break of a conductor part and disconnection of the whole is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a multi-core ceramics superconducting conductor applicable mainly to magnets and the like, and in particular, ceramics superconducting conductors are arranged inside a metal in a filament shape and in a spiral shape. The present invention relates to a method for producing a long multicore ceramics superconducting conductor having a structure.

[0002]

2. Description of the Related Art Tc such as Y system, Bi system, Tl system, etc.
Is known to exceed the liquid nitrogen temperature, and molding into various shapes has been studied for the purpose of application and utilization of such ceramic superconductor. For example, when manufacturing a wire rod, a metal sheath method is generally used. This is to fill a metal pipe with a ceramic raw material to be a superconductor to form a composite billet, and then reduce the cross-section of the composite billet to finish it into a composite wire with a desired shape and size. To do.

The wire rod obtained by the metal sheath method has a round cross section, an elliptical cross section, a square cross section, a tape-like cross section, or a multi-core wire rod formed by bundling a plurality of these, and further a metal. Various prototypes of multilayer wire rods and the like in which ceramics superconductors are arranged in a concentric cylindrical shape or in a spiral shape have been examined. As the cross-section reduction processing, conventional plastic working methods such as extrusion, rolling, drawing and swaging are applied as they are, depending on the shape of the wire to be obtained.

Materials of the metal to be composited include thermal conductivity,
Materials with excellent electrical conductivity, such as Ag, Ag alloys, C
Although u and Cu alloys can be applied, Ag and Ag alloys are often used in terms of oxygen permeability and oxidation resistance.

FIG. 4 shows an example of a multicore ceramic superconducting conductor. In FIG. 4, (a) is a multi-core wire having a round cross section in which a ceramics superconductor 2 is arranged in a concentric cylinder in a multi-core shape inside a metal 1, and (b) is a rectangular shape similarly arranged. Each of the wires is shown. On the other hand, when such a multicore ceramics superconducting conductor is used as an AC wire, for example, it is necessary to have a twisted structure for reducing the loss.

In the case of producing such twisted multifilamentary wire, conventionally, for example, a composite wire as shown in FIG. 5 has been prepared in advance, and a plurality of these are bundled and reinserted in the metal pipe. A general method is to make a billet, subject this billet to a cross-section reduction process, then add a twisting process, and further heat-treat.

[0007]

However, when a multifilamentary wire is manufactured by the method as described above, since the mechanical strength of the composite wire is small, the internal ceramic superconductor portion is discontinued by twisting (twisting). However, there is a defect that the entire wire is broken. In addition, there is a problem that it is difficult to twist an extremely long wire.

An object of the present invention is to provide a method for producing a long multicore ceramics superconducting conductor which can be applied to magnets and the like, in which there is no breakage of the wire due to twisting and the ceramics superconducting is not interrupted. ..

[0009]

The present invention was obtained as a result of various experiments for improving the above-mentioned drawbacks, and has a single-core shape or a multi-core shape composed of a composite of a ceramic raw material to be a superconductor and a metal member. A plurality of core-shaped composite sheets are spirally wound around a metal rod or pipe so that they do not overlap each other and no voids are formed, and the outside is coated with a metal as necessary. Then, there is provided a method for producing a multi-core ceramics superconducting conductor, which is characterized by performing cross-section reduction processing and heat treatment.

In the method of the present invention, first, a composite sheet of a ceramic raw material to be a superconductor and a metal is prepared. As the method, a conventional metal sheath method can be applied. For example, a ceramic raw material to be a superconductor is filled in a metal pipe, subjected to cross-section reduction processing, and finally subjected to rolling processing to obtain a composite tape. In this case, when a tape wire having a relatively narrow width is manufactured, a billet having a round cross section is formed, and when a tape wire having a wide width is manufactured, the billet shown in FIG.
A square billet as shown in can be used. Further, as shown in FIG. 1B, a multi-core type billet can be used. Such a composite billet is subjected to cross-section reduction processing to produce a tape-shaped composite wire as shown in FIG.
The width and thickness of the tape wire can be variously determined according to the size of the multifilament wire to be obtained.

The tape-shaped composite wire 3 shown in FIG. 2 (a) is a single core type obtained by using the single core type billet shown in FIG. 1 (a), and the tape type composite wire shown in FIG. 2 (b). The composite wire 4 is
It is a multi-core type obtained by using the multi-core type billet shown in FIG.

Next, as shown in FIG. 3, these tape wires are spirally wound around the metal pipe or the round bar 5. The winding is performed by spirally winding so that the tape wire rods 3 or 4 do not overlap each other and no void is formed. This is because the cross-sectional shape of the ceramic is not deteriorated or discontinued even by the subsequent processing. After wrapping in a spiral like this,
It is again inserted into the metal pipe to form a composite billet.

FIG. 3 (a) is an example in which the tape-shaped composite wire 3 shown in FIG. 2 (a) is wound, and FIG. 3 (b) is shown in FIG. 2 (b).
Examples of winding the tape-shaped composite wire 4 shown in FIG.

The winding pitch is not limited and can be selected as appropriate. Further, in the configuration shown in FIG. 3, one layer is wound without being overlapped, but the present invention is not limited to this, and if it is configured in multiple layers, higher Ic can be achieved, and the size of the ceramic superconductor filament can be increased. To be small,
And it is possible to increase the number. Further, the winding direction is not limited to one direction, and the winding directions may be changed from each other.

As the tape-shaped composite wire rods 3 and 4 to be wound, it is possible to use only one type shown in FIG. The shape of the metal pipe or the rod 5 may be a round shape or a square cross section.

The composite billet obtained as described above is subjected to cross-section reduction processing to finish into a multi-core, multi-layer composite wire rod having a desired shape and size. In this case, as a method of cross-section reduction processing, it is desirable to use processing such as extrusion, swaging, rolling, etc., which mainly uses compressive force. Here, it is also possible to perform cross-section reduction processing without using a metal pipe. The cross-sectional shape of the obtained wire may be round, square, or the like.

Finally, the wire rod thus obtained is heat-treated to obtain a multicore ceramics superconducting conductor. In this heat treatment, it is possible to form the wire into a coil shape in advance and then perform the heat treatment, or to form the wire into a coil shape after the heat treatment.

In the case of the method of the present invention described above, the multicore ceramics superconducting conductor obtained is twisted because the superconducting conductors are spirally arranged inside.
It becomes the structure that was removed. Further, since the composite body having a structure covered with metal is plastically processed, it is possible to manufacture a long wire rod without interruption of the superconductor portion or disconnection of the whole.

[0019]

EXAMPLES The present invention will be described in more detail below with reference to examples.

(Example 1) Bi ₂ O ₃ , PbO, SrC
Bi: Pb: Sr: Ca: Cu = 1.6: 0.4: in molar ratios of primary raw material powders such as O ₃ , CaCuO ₃ , and CuO.
The mixture was mixed and mixed so as to be 2: 2: 3, and the mixture was calcined in the air at 800 ° C. for 100 hours, and then further pulverized to prepare a calcined powder.

This calcined powder is CIP molded to have an outer diameter of 15 m.
Finished into a cylindrical body with a size of about m. This molded body was inserted into an Ag pipe having an outer diameter of 25 mm and an inner diameter of 15 mm to obtain a composite billet. This composite billet was swaged and rolled to obtain a single core tape wire having a width of 5 mm and a thickness of 0.5 mm.

The tape wire thus obtained was spirally wound around an Ag pipe having an outer diameter of 30 mm and an inner diameter of 20 mm. In this case, the number of sheets per layer is 18, and the winding pitch is 3
It was 0 mm, and was wound so that the tape wire rods would not wrap each other and voids would not occur. The number of layers was 20, and they were all wound in the same direction.

This was further inserted into an Ag pipe having an outer diameter of 60 mm and an inner diameter of 51 mm to obtain a composite billet again. This composite billet was swaged to an outer diameter of 3 mm, and finished into a round wire rod. This round wire is
Heat treatment was performed at 830 ° C. for 200 hours to obtain a multilayer ceramic superconducting conductor.

The Ic of the obtained multi-layer wire material at a liquid nitrogen temperature and 0 magnetic field was measured, and a high Ic of 59 A was obtained. Further, the shapes of the longitudinal section and the transverse section of this multilayer wire rod were excellent.

(Example 2) The calcined powder obtained in Example 1 was filled in a square billet as shown in Fig. 1 (b) and then rolled to obtain a width of 3 mm and a thickness of 0.5 mm. This is a multi-core tape wire rod. The dimension of the ceramic inside the multi-core tape wire is 3 mm in width, and the number of cores is 6.

The multifilamentary tape wire thus obtained has an outer diameter of 30 m.
m and an inner diameter of 20 mm were spirally wound on a pipe made of Ag. The winding pitch was 60 mm, and the winding was performed so as not to wrap each other and voids. The number of layers was 30, and all layers were wound in the same direction.

This was further inserted into an Ag pipe having an outer diameter of 70 mm and an inner diameter of 63 mm to obtain a composite billet again. This composite billet was swaged to an outer diameter of 5 mm and then rolled to form a square wire rod of 2 mm × 3 mm. This rectangular wire rod was heated in air at 830 ° C for 2
Heat treatment was performed for 00 hours to obtain a multilayer ceramic superconducting conductor.

The Ic at a liquid nitrogen temperature and a 0 magnetic field of the obtained multilayer wire was measured, and a high Ic of 79 A was obtained. Further, the shapes of the longitudinal section and the transverse section of this multilayer wire rod were excellent.

(Comparative Example) Using the calcined powder obtained in Example 1, a round wire having an outer diameter of 5 mmφ and an outer diameter of ceramics of 3 mmφ was produced. After bundling 50 of these, the outer diameter is 50
The composite billet was obtained by inserting it into an Ag pipe having an mmφ and an inner diameter of 40 mmφ. This composite billet was swaged to an outer diameter of 3 mmφ and finished into a round wire rod. This round wire rod was twisted to have a pitch of 30 mm. The obtained wire was heat-treated in air at 830 ° C. for 200 hours to obtain a multilayer ceramic superconducting conductor.

The liquid nitrogen temperature of the obtained multilayer wire is
As a result of measuring Ic at 0 magnetic field, it was 14 (A), which was extremely inferior to the multilayer wire rod obtained by the method of the present invention. After the measurement, the vertical cross section of the sample was observed under a microscope, and it was found that the ceramic superconductor was partially discontinued.

[0031]

As described in detail above, according to the method of the present invention, it is possible to easily obtain a multicore ceramics superconducting conductor having an excellent cross-sectional shape and high Ic characteristics. The multi-core ceramics superconducting conductor obtained by the method of the present invention can be mainly applied as a ceramics superconducting conductor for magnets.

[Brief description of drawings]

FIG. 1 is a view showing single-core and multi-core square billets used in the method of the present invention.

FIG. 2 is a view showing a tape-shaped composite wire which is an intermediate product of the method of the present invention.

FIG. 3 is a view in which the tape-shaped composite wire rod shown in FIG. 2 is spirally wound on a metal pipe or a round bar.

FIG. 4 is a diagram showing an example of a conventional multicore ceramics superconducting conductor.

FIG. 5 is a view showing a composite wire rod for obtaining a conventional multicore ceramics superconducting conductor.

[Explanation of symbols]

3 ... Single-core tape-shaped composite wire rod, 4 ... Multi-core tape-shaped composite wire rod.

Claims (1)

[Claims] 1. A metal rod or pipe on which a plurality of composite sheets made of a composite of a ceramic raw material to be a superconductor and a metal member do not overlap with each other and do not form voids. A method for producing a multicore ceramics superconducting conductor, which comprises spirally winding a wire around the core, coating the outside with a metal as necessary, and then subjecting it to cross-section reduction processing and heat treatment.