JPH08190824A - Method for manufacturing compound-based superconducting wire and coil - Google Patents

Abstract

(57) [Summary] [Objective] By joining, a long compound-based superconducting wire and coil having excellent electrical and mechanical properties are manufactured. [Structure] According to the jelly roll method, the bronze method, or the like, a plurality of wire rods in which a metal as a raw material of a compound-based superconductor and a stabilizing metal are combined are prepared. Next, the wires 11a and 11b are overlapped with each other by a length L along the longitudinal direction. The length L is 30 times or more the wire diameter d of the wire.
Then, the overlapped portions are twisted together. The twisting pitch P is 15 times or less the wire diameter d. The wire material joined by such twisting is heat-treated to generate a compound superconductor.

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 compound-based superconducting wire and coil, and more particularly to a method for producing a wire and coil for a superconducting magnet in applications such as analytical NMR, nuclear fusion and power storage. .

[0002]

2. Description of the Related Art Since a compound type superconducting material is poor in workability, it is difficult to directly process it into a fine wire like an alloy type superconducting material such as Nb-Ti. Therefore, as a method of obtaining a compound-based superconducting wire, generally, after compounding a plurality of kinds of metals that are raw materials of the compound superconducting material and copper for stabilization, wire drawing is performed to obtain a fine wire, which is finally obtained. The method of heat treatment is adopted.

However, since these composite materials also have poor workability, it is difficult to obtain a long wire by only drawing. Therefore, a method of obtaining a required length by connecting the wire rods has been considered.

There is a method of welding, for example, for connecting the wires. However, in the method of applying heat such as welding,
The heat reacts with the composite material, and a compound is produced at the time of bonding. The joint portion where the compound is formed has low mechanical strength, and it is difficult to perform twisting or coil winding in the next step. Even if twisting or coil winding could be performed, in the final heat treatment for producing the compound superconductor, the force applied to release the strain applied to the wire in the twisting and coil winding process causes Is likely to break.

On the other hand, as a joining method which does not apply heat, a so-called cold joint is known in which the end cross sections of the composite wire to be connected are mechanically pressure-bonded to each other. In the transition of the current in the parts connected by this method, a large resistance is generated due to the long distance through the normal conducting part. Further, since the joint portion formed by the cold joint is poor in strength against bending and twisting, the joint portion is broken in the next step of twisted wire, coil winding, or final heat treatment, as in the joining method in which heat is applied.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the conventional problems described above and provide a method for producing a long compound superconducting wire and coil having excellent electrical and mechanical properties. To do.

[0007]

A method for producing a compound-based superconducting wire according to the present invention comprises a first solid consisting of a metal selected from the group consisting of specific metal elements X and X alloys.
A second solid made of a metal selected from the group consisting of metals Y and Y alloys, which can contact the first solid and combine with X to form a compound superconductor, and the first and second solids. A step of preparing a plurality of strands made of a matrix metal for stabilizing the covering, a step of connecting two or more strands to obtain a long wire, and the obtained long wire,
A step of performing a heat treatment to generate a compound superconductor by the reaction of X and Y. In such a step, the present invention connects two or more strands, so that the strands to be spliced over a length of 30 times or more the outer diameter of the strands are overlapped, and the overlapped portion is It is characterized in that the strands are twisted together at a pitch of 15 times or less the outer diameter of the strands.

A method for producing a compound-based superconducting coil according to the present invention comprises a step of preparing a plurality of the above-mentioned strands, a step of connecting two or more strands to obtain a long wire, and the obtained long wire. The method includes a step of winding a wire to form a coil, and a step of subjecting the obtained coil to a heat treatment to generate a compound-based superconductor by a reaction of X and Y. In the above steps, since the present invention connects two or more strands, the strands to be spliced over a length of 30 times or more the outer diameter of the strands are overlapped, and the overlapped portion is It is characterized in that the strands are twisted together at a pitch not more than 15 times the length of the strands.

In the present invention, the metal element X can be Nb or V, and the metal element Y can be Sn, Al or Ga, and Nb ₃ Sn, Nb ₃ Al can be used as a compound superconductor.
Alternatively, a wire or coil containing a V ₃ Ga-based superconductor can be manufactured. Copper or a copper alloy is preferably used as a matrix for stabilization.

In the present invention, an element wire composed of X or X alloy, Y or Y alloy and a matrix metal for stabilization can be prepared by a so-called jelly roll method, a bronze method or the like.

[0011]

In the present invention, for example, FIG.
According to the jelly roll method as shown in (a), a first sheet 1 made of X or an X alloy and a second sheet 2 made of Y or a Y alloy are wound around a stabilizer 3 (jelly). Rolled). The obtained material is inserted into a stabilizer pipe and subjected to wire drawing. In the wire drawing process, the obtained wire rod can be formed into a hexagonal shape as necessary (FIG. 1 (b)). The wire rod obtained by wire drawing is cut to obtain a plurality of segments as necessary.

The obtained segments are bundled as shown in FIG. 1 (c) and filled in a pipe made of, for example, a stabilizing material. The assembled wire rod is subjected to wire drawing.
After wire drawing, the wire obtained has a plurality of X / Y filaments 20 in a matrix 10 as shown in FIG.

In the present invention, for example, the wire rods obtained by the above steps are connected together. When joining,
As shown in FIG. 2A, the wires 11a and 11b are
The length L is overlapped along the longitudinal direction. L is 30 times or more the wire diameter (outer diameter) d of the wire. Then, FIG.
As shown in (b), the overlapped portions are twisted together. The twisting pitch P is 15 times or less the wire diameter d. By performing twisting according to such dimensions, the strength of the joint portion against bending, twisting, pulling, etc. becomes strong, and the joint portion can sufficiently withstand the twisted wire, coil winding, heat treatment, etc. performed in the next step. it can. on the other hand,
When the length L is 30 times or less of the wire diameter d or the pitch P is 15 times or more of the wire diameter d, the strength of the connection portion against bending, twisting, pulling, etc. decreases, and twisted wires, coil winding, heat treatment, etc. Causes separation of the joints. In particular, when the length L of the connecting portion is 30 times or less of the wire diameter d, the critical current characteristics of the obtained superconducting wire material are significantly deteriorated due to the remarkable resistance of the normal conducting portion in the transition of current. . After joining the wires, diffusion joining is performed at the joining portion by heat treatment for forming the compound superconductor. According to the present invention, generation of resistance is suppressed at the junction, and current transition can be performed quickly.

Among the compound superconductors, Nb ₃ Sn type, N type
When producing b ₃ Al-based or V ₃ Ga-based superconductors, a high temperature of 600 ° C. or higher is used for producing these superconductors. Due to this high temperature, the fusion of the matrix of the joint portion, particularly copper, is sufficiently performed, and excellent electrical characteristics are obtained.

When forming a coil, the wire material joined according to the present invention is wound and then heat treated for reaction.

As described above, the joining according to the present invention makes it possible to form a long compound-based superconducting wire or coil having excellent electrical and mechanical properties.

[0017]

【Example】

Example 1 The outer diameter (d) was 0.9 mmφ according to the jelly roll method.
A Cu / Nb / Al composite multifilamentary wire was manufactured. Next, Table 1
The test was conducted under the conditions shown in.

In Example 1 and Comparative Examples 1-2 to 6, the obtained wire rods were joined. On the other hand, in Comparative Example 1-1, the wire rods were not joined. Example 1 according to the invention
In joining, the length of the joined portion (corresponding to L in FIG. 2A) is 30 mm (33 times the outer diameter of the wire), and the twist pitch (corresponding to P in FIG. 2B) is 10 mm (wire Outer diameter of 11
Times). On the other hand, in the joining of Comparative Examples 1-2 to 5, Table 1
As shown in, the length of the joint portion is 10 mm to 30 mm,
Bonding was performed by changing the twist pitch within the range of 10 mm to 20 mm. In Comparative Examples 1-6, cold joint was performed according to the conventional method.

Each of the obtained wire rods was wound into a coil of 40 mmφ and then heat treated at 800 ° C. to form Nb ₃ Al.
Was generated. About the obtained coil, by the 4-terminal method,
The voltage generated during energization was read. And 0.1 μV / c
The critical current value was measured with reference to the point where an electric field of 1 μV / cm was generated. Table 1 shows the measurement results.

Example 2 According to the bronze method, Cu having an outer diameter (d) of 0.9 mmφ
A / Nb / CuSn composite multifilamentary wire was produced. Next, a test was conducted under the conditions shown in Table 1.

In Example 2 and Comparative Examples 2 to 2-6, the obtained wire rods were joined. On the other hand, in Comparative Example 2-1, the wires were not joined. In the joining of Example 2 according to the present invention, the length of the joined portion (corresponding to L) is 30 mm (wire rod outer diameter is 33 times), and the twist pitch (corresponding to P) is 10 mm.
(11 times the outer diameter of the wire). On the other hand, Comparative Examples 2 to 2-5
As shown in Table 1, the length of the joint is 10
mm to 30 mm, and the twist pitch was changed within the range of 10 mm to 20 mm, and the joining was performed. In Comparative Examples 2-6, cold joint was performed according to the conventional method.

Each of the obtained wires was wound into a coil of 40 mmφ and then heat-treated at 650 ° C. to obtain Nb ₃ Sn.
Was generated. About the obtained coil, by the 4-terminal method,
The voltage generated during energization was read. And 0.1 μV / c
The critical current value was measured with reference to the point where an electric field of 1 μV / cm was generated. Table 1 shows the measurement results.

[0023]

[Table 1]

From the above results, it has been clarified that when the bonding is carried out according to the present invention, a long wire having superconducting characteristics substantially equal to those of the wire not bonded can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view showing a process for producing a compound-based superconducting wire.

FIG. 2 is a schematic view showing a process for joining wires according to the present invention.

[Explanation of symbols]

 11a, 11b strands

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Claims (4)

[Claims] 1. A first solid made of a metal selected from the group consisting of specific metal elements X and X alloys, and the first solid.
A second solid made of a metal selected from the group consisting of metals Y and Y alloys, which is capable of forming a compound-based superconductor by being combined with X to form a compound superconductor, and the first and second solids.
The step of preparing a plurality of strands made of a matrix metal for stabilizing and covering the solid, a step of connecting two or more strands to obtain a long wire, and the obtained long wire. And a step of producing a compound-based superconductor by the reaction of X and Y by heat treatment, and for connecting two or more of the strands, a length of 30 times or more the outer diameter of the strands. For the part where the strands to be joined are overlapped and overlapped,
A method for producing a compound-based superconducting wire, characterized in that the strands are twisted together at a pitch of 15 times or less the outer diameter of the strand. 2. The X is Nb or V, the Y is Sn, Al or Ga, and Nb ₃ Sn, Nb ₃ Al or V ₃ Ga based superconductor is produced as a compound superconductor. Item 2. A method for producing a compound-based superconducting wire according to Item 1. 3. A first solid made of a metal selected from the group consisting of specific metal elements X and X alloys, and the first solid.
A second solid made of a metal selected from the group consisting of metal elements Y and Y alloys capable of forming a compound-based superconductor by being combined with X to form a compound-based superconductor, and the first and second solids. A step of preparing a plurality of strands made of a matrix metal for stabilization covering a solid; a step of connecting two or more strands to obtain a long wire; and the obtained long wire. In order to connect two or more of the strands, the method includes a step of winding and forming a coil, and a step of subjecting the obtained coil to a heat treatment to generate a compound-based superconductor by the reaction of the X and Y. , The wires that are to be joined together over a length of 30 times or more the outer diameter of the wires, and the overlapped portion,
A method for producing a compound-based superconducting coil, characterized in that the strands are twisted together at a pitch that is 15 times or less the length of the strands. 4. The X is Nb or V, the Y is Sn, Al or Ga, and Nb ₃ Sn, Nb ₃ Al or V ₃ Ga based superconductor is produced as a compound superconductor. Item 3. A method for manufacturing a compound-based superconducting coil according to Item 3.