JPH0597410A - Production of multilayered multi-core ceramic superconductor - Google Patents

Abstract

PURPOSE:To produce a multilayered multi-core ceramic superconductor having high Ic characteristics and an excellent cross-sectional shape. CONSTITUTION:A combined body 6 consisting of powdery starting material for a ceramic superconductor and a metal is rolled down by repeating a first rolling process 7 in which rolling is carried out from opposite two directions while imparting flowability to the starting material and a second rolling process 8 in which rolling is carried out from opposite two directions perpendicular to the above-mentioned two directions while imparting flowability to the starting material. These processes 7, 8 are repeated at least once or more.

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-layered, multi-core ceramics superconducting conductor applicable to magnets, cables, etc., and particularly to the production of a multi-layer, multi-cores ceramics superconductor having an excellent cross-sectional shape and superconducting properties. Regarding the method.

[0002]

2. Description of the Related Art YBaCuO system, Bi (Pb) SrCa
Ceramic superconductors such as CuO type and TlBaCaCuO type in which Tc exceeds the liquid nitrogen temperature are known, and for the purpose of applying such ceramic superconductors,
Molding into various shapes has been studied. For example,
A metal sheath method is generally used when producing a wire. This is to fill a metal pipe with a raw material of ceramics to be a superconductor, and then subject it to a cross-section reduction processing to obtain a composite wire having a desired shape and dimension, and then heat-treat it to obtain a ceramics superconducting conductor.

The shape of the wire obtained by the metal sheath method is a round, elliptical, quadrangular, tape-shaped cross section, or a multi-core wire having a shape in which a plurality of these are bundled, and further, the inside of metal. In addition, various prototypes of multi-layer wire rods having a structure in which ceramics superconductors are arranged in a concentric cylindrical shape or in a spiral shape have been studied. As the cross-section reduction processing, conventional plastic working techniques such as extrusion, rolling, swaging, and drawing are applied as they are, depending on the shape of the obtained wire.

As the material of the metal, a material having excellent thermal conductivity and electrical conductivity, for example, Ag, Ag alloy, Cu, Cu alloy or the like can be applied, but Ag and Ag alloys are used in view of oxygen permeability. There are many.

FIG. 4 is a sectional view showing an example of a multi-layer wire. In FIG. 4, (a) shows a structure in which the ceramics superconductor 2 is arranged in a concentric cylindrical shape inside the metal 1 with a round cross section, and (b) shows a structure in which the cross section is rectangular and has a spiral shape. Show. Applying such a multilayer wire to a conductor such as a coil has been studied.

Conventionally, as a method of manufacturing a multilayer wire rod as shown in FIG. 4 (a), one or both of the inner surface and the outer surface of a metal pipe is coated with a raw material of ceramics to be a superconductor, or is sprayed. A composite billet is formed by attaching them by a method to form a composite billet having different outer diameters, and then subjecting the billet to cross-section reduction processing and heat treatment. Further, in the case of producing a multilayer wire rod as shown in FIG. 4B, an Ag sheath tape-like wire rod produced by attaching a ceramic raw material to be a superconductor to one side or both sides of a metal tape or by an ordinary method. Using
Attempts have been made to subject a composite billet obtained by spirally winding it onto a metal round bar or pipe to subject it to cross-section reduction processing and heat treatment. A multifilamentary wire can also be manufactured by a method substantially similar to those of these multilayer wires.

For example, when a Bi-based ceramic superconductor is used, the crystal orientation is made by compression processing to improve the characteristics. The shape of the conductor used for the coil may be round, but it is preferable to use a rectangular wire rod having excellent dimensional accuracy. This is because when the solenoid coil is manufactured, the winding can be performed in an aligned manner, and the space factor can be increased.

[0008]

DISCLOSURE OF THE INVENTION For example, in the case of producing a multilayer wire rod as shown in FIG. 4 (b) by subjecting a composite billed formed by winding a tape-shaped wire rod in a spiral shape to a cross-section reduction process, The ceramic superconductor on the contact surface can be improved in Jc by the crystal orientation, but the ceramic superconductor on the surface perpendicular to it has no compressive force.
There is a problem that it does not contribute to the increase of c.

An object of the present invention is to provide a method for producing a multi-layer, multi-core ceramics superconducting conductor having high Ic characteristics and an excellent sectional shape.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, in which a composite of a ceramic superconductor raw material powder raw material and a metal is subjected to cross-section reduction processing to obtain a desired shape and size. A method for manufacturing a multi-layered, multi-core ceramics superconducting conductor, which comprises forming a composite wire and then performing heat treatment, wherein the cross-section reduction processing is performed in two opposite directions while imparting fluidity to the ceramics superconductor raw material powder. From the first rolling step of performing rolling processing from 1 to 2, while imparting fluidity to the ceramic superconductor raw material powder.
Provided is a method for producing a multi-layer, multi-core ceramics superconducting conductor, characterized in that a second rolling step in which rolling is performed from two opposite directions perpendicular to the direction is repeated at least once.

In the method of the present invention, first, a multi-layer or multi-core composite billet is produced. As the method, for example, the known means described above can be applied.
For example, as shown in FIG. 4A, the ceramic raw material 1 to be a superconductor is applied to one or both of the inner surface and the outer surface of the metal pipe 2 by a method such as coating or thermal spraying, and those having different outer diameters are attached. In the case where the composite billet is formed by concentric cores or when a multilayer wire material as shown in FIG. 4B is produced, the ceramic raw material 1 to be a superconductor is attached to one or both surfaces of the metal tape 2, or Alternatively, it is also possible to use an Ag sheath tape-shaped wire produced by a usual method and spirally wind this on a metal round bar or pipe.

A composite billet for producing a multi-core wire can be produced in substantially the same manner. The shape of these composite billets may be rectangular as well as circular in cross section.

Alternatively, a square billet 4 having a plurality of voids 3 as shown in FIG. 5 may be used. In addition, tape wire is made in advance, and after stacking multiple sheets,
It is also possible to insert it again into the rectangular pipe 5 as shown in FIG. 6 to form a composite billet.

Next, the composite billet obtained as described above is subjected to cross-section reduction processing. The method is performed as follows, for example. That is, as shown in FIG. 1, the first rolling roll 7 is disposed on the two opposing surfaces of the composite billet 6, and the first rolling roll 7 is disposed downstream of the first rolling roller 7 on the other two opposing surfaces at right angles to the opposing two surfaces. Two rolling rolls 8 are arranged, pressure is applied to each of the two opposing surfaces, and rolling is sequentially performed. At that time, rolling is performed while imparting fluidity to the ceramic superconductor raw material powder in the composite billet. Usually, these steps are repeated multiple times.

To impart fluidity to the ceramic superconductor raw material, for example, a vibration plate is attached to the shaft of the composite billet 6 or the rolling rolls 7 and 8, and a vibrator is attached to them.
By adding vibration.

The vibration is not limited to the vibrator, but can be applied by using an ultrasonic transducer. In addition, imparting fluidity to the ceramic raw material is not limited to imparting mechanical vibration, and may be performed by another method.

Before the rolling process described above, the composite billet 6 may be swaged in advance. Further, the Ic characteristic is further improved by repeating such rolling and heat treatment a plurality of times.

Finally, a ceramics superconducting conductor can be obtained by performing heat treatment under predetermined conditions. The temperature of this heat treatment is usually 830 to 880 ° C.

According to the method of the present invention described above, a compressive force is applied to the entire surface of the ceramic superconductor, so that crystal orientation becomes possible, and as a result, Jc is improved,
It contributes to the increase of Ic. There is no restriction on the shape of the wire, and any of multi-core, multi-layer, etc. may be used.

Further, in the method of the present invention, for example, as shown in FIG.
As shown in, it is also possible to perform the cross-section reduction processing while sequentially performing the compression processing using four flat plates. Further, it is also possible to perform them at the same time, for example, using a four-direction roll as shown in FIG.

[0021]

EXAMPLES The present invention will be described more specifically below based on examples.

(Example 1) Bi ₂ O ₃ , PbO, SrC
Each primary raw material powder such as O ₃ , CaCO ₃ , and CuO is added to B
i: Pb: Sr: Ca: Cu = 1.6: 0.4: 2:
After mixing and mixing so as to have a molar ratio of 2: 3, calcination is performed in the air at 800 ° C. for 50 hours, and the obtained calcined body is further pulverized to prepare calcined powder with an average particle size of about 5 μm. did. This was filled in a rectangular Ag pipe and rolled to produce an Ag sheath tape-shaped wire having a width of 100 mm and a thickness of 0.5 mm.

The tape-shaped wire thus obtained was used for A having an outer diameter of 10 mmφ.
A 23-layer spiral bar was wound around a g-made round bar, and this was further inserted into an Ag pipe having an outer diameter of 50 mmφ and an inner diameter of 40 mmφ to obtain a composite billet. The resulting composite billet has an outer diameter of 5 mmφ
After performing swaging until it becomes, a compression process was performed by applying a vibration to the compression jig by a vibrator as shown in FIG. 1 to obtain a 3 mm × 4 mm square wire rod.

Next, after heat-treating at 830 ° C. for 50 hours in the atmosphere, compression processing is performed again by the method shown in FIG.
A 2 mm × 3 mm square wire rod was obtained. This was heat-treated in the atmosphere at 830 ° C. for 50 hours in the same manner as described above to obtain a multilayer ceramic superconducting conductor.

The obtained ceramics superconducting conductor was measured for Ic in liquid nitrogen at 0 magnetic field.
The excellent characteristics of 35 (A) were obtained.

As a result of obtaining the orientation rate of the ceramics superconductor near the center, it was 82 (%). The cross-sectional shape was relatively excellent.

(Example 2) The calcined powder obtained in Example 1 was applied to the hole 1 of the square multicore Ag pipe 9 as shown in FIG.
It is filled in 0 and rolled, and the width is 100 mm and the thickness is 0.
A 5 mm Ag sheath tape-shaped wire was prepared. The raw material of the ceramic superconductor in the inside is 5 mm in width and 15 cores.
Place the obtained tape wire on an Ag round bar with an outer diameter of 10 mmφ.
It was wound in a three-layer spiral shape, and this was further inserted into an Ag pipe having an outer diameter of 50 mmφ and an inner diameter of 40 mmφ to obtain a composite billet.

The composite billet thus obtained was swaged to an outer diameter of 5 mmφ and then compressed by a method shown in FIG. 1 while applying vibration to the compression jig with a vibrator to obtain 3 mm × 4 mm. It was a square wire rod.

Next, the rectangular wire rod thus obtained was placed in the air at 830
After heat treatment at 50 ° C. for 50 hours, compression processing was performed again by the method shown in FIG. 1 to obtain a square wire rod of 2 mm × 3 mm. This was heat-treated in the atmosphere at 830 ° C. for 50 hours in the same manner as described above to obtain a multilayer ceramic superconducting conductor.

With respect to the obtained ceramics superconducting conductor, Ic was measured in liquid nitrogen at 0 magnetic field.
The excellent characteristics of 29 (A) were obtained.

As a result of obtaining the orientation rate of the ceramics superconductor near the center, it was 83 (%). The cross-sectional shape was relatively excellent.

(Example 3) The calcined powder obtained in Example 1 was machined in advance to have an outer diameter of 11 mmφ and an inner diameter of 8 mmφ.
Was filled in an Ag pipe to prepare a composite billet. This was rolled to a thickness of 0.5 mm and a width of 12 mm. After laminating 10 pieces of the obtained tape-shaped wire,
The composite billet was constructed again by inserting it into an Ag rectangular pipe having outer dimensions of 14.5 mm × 7.5 mm and inner dimensions of 12.5 mm × 5.5 mm as shown in FIG.

The produced composite billet was rolled by using a four-direction roll as shown in FIG. 2 while applying vibration to each roll by a vibrator to finish it into 4 mm × 2 mm. This was heat-treated in air at 830 ° C. for 200 hours to obtain a multilayer ceramic superconducting conductor.

The obtained ceramic superconducting conductor was measured for Ic in liquid nitrogen at 0 magnetic field.
Excellent characteristics of 30 (A) were obtained. Also in this case, the orientation rate of the ceramics superconductor near the center was as high as 83 (%), and the cross-sectional shape was relatively excellent.

Comparative Example 1 The composite billet obtained in Example 1 was swaged to an outer diameter of 3 mmφ and then rolled normally to obtain a 3 mm × 4 mm square wire rod. Then, after heat treatment at 830 ° C. for 50 hours in the atmosphere, a square wire rod of 2 mm × 4.2 mm was obtained. This was heat-treated at 830 ° C. for 50 hours in the same atmosphere as described above to obtain a multilayer ceramic superconducting conductor.

The obtained ceramic superconducting conductor was measured for Ic in liquid nitrogen at 0 magnetic field. 1
2 (A), which was extremely inferior to the method of the present invention. The orientation ratio of the superconductor near the center is 56.
(%) Was low. The cross-sectional shape was inferior to the product of the present invention.

(Comparative Example 2) The composite billet produced in Example 3 was subjected to a usual rolling process to a size of 3 mm x 8 mm.
This was heat-treated in air at 830 ° C. for 200 hours to obtain a multilayer ceramic superconducting conductor.

The obtained ceramic superconducting conductor was measured for Ic in liquid nitrogen at 0 magnetic field. 1
6 (A), which was extremely inferior to the method of the present invention. The orientation ratio of the superconductor near the center is 52
(%) Was low. The cross-sectional shape was inferior to the product of the present invention.

[0039]

As described in detail above, according to the method of the present invention, it is possible to easily obtain a conductor having an excellent sectional shape. In addition, the crystal orientation of the ceramic superconductor becomes possible, and as a result, a high Ic multilayer ceramic superconductor can be obtained. The ceramic superconducting conductor obtained by the method of the present invention can be variously applied as a conductor for magnets, cables and the like.

[Brief description of drawings]

FIG. 1 is a diagram showing a step of reducing the cross section of a composite billet in the method of the present invention.

FIG. 2 is a view showing a four-direction roll for simultaneously reducing the cross section of the composite billet in four directions in the method of the present invention.

FIG. 3 is a diagram showing a square multi-core Ag pipe for obtaining a billet in Example 2.

FIG. 4 is a cross-sectional view showing an example of a multilayer wire rod.

FIG. 5 is a view showing a square composite billet.

FIG. 6 is a view showing a square pipe for obtaining a square composite billet.

[Explanation of symbols]

1 ... Ceramic superconductor raw material powder, 2 ... Metal pipe,
Metal tape, 3 ... Void, 4 ... Square composite billet, 5 ... Square pipe, 6 ... Composite billet, 7 ... First rolling roll,
8 ... Second rolling roll.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // H01B 12/10 ZAA 8936-5G (72) Inventor Naoki Uno 2-6 Marunouchi, Chiyoda-ku, Tokyo No. 1 inside Furukawa Electric Co., Ltd.

Claims (1)

[Claims] 1. A method for producing a multi-layered, multi-core ceramics superconducting conductor, which comprises subjecting a composite of a ceramics superconductor raw material powder and a metal to a cross-section reduction processing to obtain a composite wire rod having a desired shape and size, and then performing heat treatment. In the step of reducing the cross-section, the ceramic superconductor raw material powder is provided with fluidity while the first rolling step is performed in which rolling is performed from two opposing directions, and the ceramic superconductor raw material powder is provided with fluidity. In addition, the method for producing a multi-layer, multi-core ceramics superconducting conductor, characterized in that the second rolling step of rolling from two opposite directions perpendicular to the two opposite directions is repeated at least once. ..