JPH0950721A - Manufacture of superconducting cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a superconducting cable which permits great degrees of freedom in selecting materials that can be used as a material for forming reinforcing and stabilizing layers and moreover enables cost reduction. SOLUTION: A manufacturing method wherein a reinforcing layer 4 is equipped on the circumference of a core part 2 comprizing an alloy grouped superconductor or a core part 2 equipped with a material capable of becoming a superconductor by heat treatment, and furthermore a stabilizing layer 5 is equipped on the circumference thereof. A plurality of columnar bodies 43 comprizing a reinforcing material chosen among a Cu-Nb alloy, a Cu-Al alloy, and a Cu-Ag alloy are provided juxtaposedly on the circumference of the core part 2 along the direction of the length of the core part 2, and diameter reduction processing is conducted after a covering tube 44 comprizing a stabilizing material is put outside the columnar bodies 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength superconducting magnet used for a medical MRI magnet, a fusion reactor toroidal magnet, a particle accelerator magnet, a superconducting generator magnet, a magnetic levitation train magnet, and the like. A method of manufacturing a wire.

[0002]

2. Description of the Related Art Generally, a superconducting wire has a structure in which an appendage made of a stabilizing material is provided on the outer periphery of a core made of a superconductor. As a kind of such superconducting wire, an internally reinforced stable Nb ₃ Sn-based superconducting wire is known. FIG.
It shows an example of an Nb ₃ Sn based superconducting wire of internal reinforcing and stabilizing type. This internal reinforcing and stabilizing Nb ₃ Sn based superconducting wire 1
Is a core portion 2 in which a myriad of extremely fine Nb ₃ Sn superconducting filaments are arranged inside a base made of Cu-Sn alloy.
A reinforcing layer 4 made of Cu-Nb or the like is provided on the outer periphery of the diffusion prevention layer 3 and Cu or Al is further provided on the outer periphery thereof.
A stabilizing layer 5 made of, for example, is provided. Internally reinforced and stabilized Nb ₃ Sn-based superconducting wire 1 having such a structure
In comparison with a superconducting wire having a structure not having a reinforcing layer, is not required to be reinforced from the outside, and thus has been suitably used for producing a compact superconducting magnet.

Next, such internal reinforcement stabilizing type Nb ₃
A general method for manufacturing the Sn-based superconducting wire 1 will be described with reference to FIG. First, a rod-shaped core material 10 made of Nb as shown in FIG. 6 (A) is covered with a tube body 11 made of Cu—Sn alloy, and the whole is reduced in diameter as shown in FIG. 6 (B). The complex 14 is obtained. Next, as shown in FIG. 6 (C), a plurality of the composite bodies 14 are assembled to form a Cu—Sn alloy tube body 15.
6 and then further reduced in diameter, and the primary strand 1 shown in FIG.
Get 6. Next, as shown in FIG. 6 (E), a plurality of primary wires 16 are assembled into a tubular body 1 made of a Cu—Sn alloy.
7 and further reduce the diameter to produce a secondary wire 18 as shown in FIG. 6 (F).

Next, a plurality of the secondary wires 18 are assembled and inserted into a Cu pipe 20 as shown in FIG. 6 (G), and then the diffusion prevention layer 3 should be formed outside the pipe 20. The diffusion preventive tube 22 made of Ta or Nb is covered, and then Cu- which is to be the reinforcing layer 4 is provided outside the diffusion preventive tube 22.
A pipe-shaped reinforcing pipe 23 made of Nb or the like is covered, and then a covering pipe 24 made of Cu or the like to be the stabilizing layer 5 is covered on the outside of the reinforcing pipe 23, and the whole is further reduced to a diameter to finally obtain it. After diameter, by performing diffusion heat treatment,
To produce an Nb ₃ Sn superconducting filament by reacting an Nb ultrafine filament inside the secondary wire 18 with Sn to produce an internal reinforcing and stabilizing Nb ₃ Sn superconducting wire 1 as shown in FIG. You can

[0005]

However, in the conventional method for manufacturing the superconducting wire, since it is necessary to use the pipe-shaped reinforcing pipe 23 as the material for forming the reinforcing layer 4, it is necessary to form the reinforcing layer 4. Even if the metal has good mechanical characteristics, it is difficult to make a pipe having poor machinability and workability into a pipe, so that the degree of freedom in selecting a material that can be used as the material for forming the reinforcing layer 4 was small. . Also,
Even if the metal has good machinability and workability, there is a problem in that it takes a high cost to manufacture the reinforcing tube 23 by processing the pipe, and as a result, the cost of the superconducting wire also increases.

The present invention has been made in view of the above circumstances, and provides a method of manufacturing a superconducting wire which has a high degree of freedom in selecting a material that can be used as a reinforcing layer forming material and which can reduce the cost. Especially.

[0007]

According to a first aspect of the present invention, a reinforcing layer is provided on the outer periphery of a core portion made of an alloy-based superconductor or a core portion made of a material that becomes a superconductor by heat treatment. Further, in the method for manufacturing a superconducting wire in which a stabilizing layer is provided on the outer periphery, in the outer periphery of the core portion, a Cu-Nb alloy, a Cu-Al alloy, and a Cu-Ag alloy are provided along the longitudinal direction of the core portion.
Manufacture of a superconducting wire comprising a step of additionally providing a plurality of columnar bodies made of a reinforcing material selected from alloys, covering the outer side of the columnar bodies with a covering tube made of a stabilizing material, and then performing a diameter reduction process. The method was used as a means for solving the above problems. Further, in the invention according to claim 2, in the method for producing a superconducting wire according to claim 1, a diffusion prevention layer is formed between the core part and a plurality of columnar bodies attached to the outer periphery of the core part. A method of manufacturing a superconducting wire including steps is used as a means for solving the above problems.

[0008]

1 and 2 show an example in which the present invention is applied to a method of manufacturing an Nb ₃ Sn superconducting wire of internal reinforcing and stabilizing type. To manufacture a superconducting wire, first, Figure 1
As shown in (A), Cu is added to the core material 30 made of Nb rod.
A —Sn alloy tube 31 is covered, and the diameter is reduced to a desired diameter by a diameter reduction process such as swaging or drawing to produce a composite 34 shown in FIG. The core material 30
It is preferable to use Nb or Nb to which Ti is added. When Ti is added, the critical current characteristics in a high magnetic field are improved as compared with the case where Ti is not added.
The tubular body 31 is not limited to a single tubular body as shown in the drawing, but a tubular body having a shape in which a plurality of through holes are formed is used, and the core material 30 is provided in each of the plurality of through holes. It can also be inserted to form a composite.

Next, a plurality of the composites 34 are assembled and housed in a Cu--Sn alloy tube 35 as shown in FIG. 1C to reduce the diameter, and the primary strand shown in FIG. As shown in FIG. 1 (E), a plurality of primary wires 36 are assembled and inserted into a tubular body 37 made of a Cu—Sn alloy. A secondary strand (secondary assembly line) 38 as shown in F) is produced. This secondary strand 3
The internal structure of No. 8 has a structure in which a large number of ultrafine filaments made of Nb are dispersed inside a matrix made of Cu—Sn alloy. A plurality of secondary wires 38 may be collected, inserted into a Cu-Sn alloy tube, and subjected to a diameter reducing treatment a plurality of times to prepare a composite. In addition,
When the Sn concentration of the Cu—Sn alloy used for forming the secondary strand 38 is low, a Sn plating layer may be formed on the outer periphery of the Cu—Sn alloy and used in the following steps.

Next, a plurality of the secondary wires 38 are assembled and inserted into a Cu pipe 40 as shown in FIG. 1 (G), and Ta or Ta which is to be a diffusion prevention layer is formed on the outer periphery of the Cu pipe 40. A diffusion prevention tube 42 made of Nb is covered. Although a plurality of secondary strands 38 are assembled and inserted into the Cu pipe 40 here, the diffusion barrier 42 is covered, but the secondary strands (secondary strands) may be selected depending on the target superconducting wire. ) 38
Alternatively, the diffusion prevention tube 42 may be directly covered on the outer circumference of, and used in the following steps. Then, as shown in FIG.
A plurality of columnar bodies 43 made of a reinforcing material to be a reinforcing layer are additionally provided along the longitudinal direction of the diffusion prevention tube 42 on the outer periphery of the column, and then a stabilizing layer to be a stabilizing layer is provided outside the columnar bodies 43. A covering tube 44 made of a material is covered, and then the whole is reduced in diameter to a diameter to finally obtain a strand.

The reinforcing material forming the columnar body 43 is C
A metal selected from u-Nb alloy, Cu-Al alloy, Cu-Ag alloy and the like is used. When a Cu—Nb alloy is used as the columnar body 43, the columnar body 43 has a structure in which a large number of Nb filaments are dispersed and arranged inside a Cu metal matrix. The columnar body 43 is manufactured by utilizing the property that both elements of Cu and Nb hardly form a solid solution with each other. When the Cu—Nb alloy is cast from the molten metal, it is contained in the Cu matrix. An ingot in which Nb dendrites are formed can be obtained, and the Nb dendrites can be stretched and processed into a filament by cold drawing the ingot, thereby forming a Cu matrix. A structure in which Nb filaments are dispersed and arranged inside is obtained. This Nb filament is C
Although they are dispersed and arranged in the matrix of u, the Nb filaments reinforce the matrix of Cu, so that the columnar body 43 has a higher yield strength than that made of Cu. Furthermore, N
Since b hardly forms a solid solution in Cu, the conductivity of the columnar body 43 does not decrease, and the conductivity of the columnar body 43 is sufficiently high. Further, as the stabilizing material forming the covering tube 44, a metal selected from Cu, Al, etc. is used.

Then, the above-mentioned strand is subjected to a diffusion heat treatment by heating it at 500 to 700 ° C. for several tens to several hundreds of hours, whereby an internal reinforcement stabilizing type N which is almost the same as that shown in FIG.
The b ₃ Sn based superconducting wire 1 can be manufactured. Doing diffusion heat treatment as described above, Nb ₃ Sn superconductor Nb ₃ Sn superconducting filaments ultrafine inside of the base consisting of the Cu-Sn alloy are arranged structure.

The internal reinforcing and stabilizing type Nb ₃ Sn superconducting wire 1 produced in this way is composed of a core portion 2 in which a myriad of Nb ₃ Sn superconducting filaments are arranged inside a base made of Cu-Sn alloy. From the diffusion preventing layer 3 provided on the outer periphery of the core portion 2, the reinforcing layer 4 provided on the outer periphery of the diffusion preventing layer 3, and the stabilizing layer 5 further provided on the outer periphery of the reinforcing layer 4. It is configured. Since the reinforcing layer 4 is formed on the outer periphery of the core 2, the internal reinforcing and stabilizing Nb ₃ Sn-based superconducting wire 1 having such a structure has excellent mechanical strength,
Further, since the diffusion preventing layer 3 is formed on the outer periphery of the core portion 2, Sn does not diffuse to the stabilizing layer 5 which is the outermost layer, and the stabilizing layer 5 is prevented from being contaminated by the diffusion of Sn.

In the method of manufacturing the Nb ₃ Sn superconducting wire of the internal reinforcement stabilizing type of this example, Nb ₃ S is formed by heat treatment.
n A plurality of columnar bodies 43 made of a reinforcing material are provided along the longitudinal direction of the core portion 2 provided on the outer periphery of the core portion 2 having a material to be a superconductor, and stabilized outside the columnar bodies 43. By including a step of performing a diameter reduction process after covering the covering pipe 44 made of a material, it is not necessary to use a pipe-shaped reinforcing pipe as the reinforcing layer 4 forming material. As long as the metal has good mechanical properties and can be formed into a columnar shape, it can be used even if it has poor machinability and workability, so that the degree of freedom in selecting a material that can be used as the material for forming the reinforcing layer 4 increases. Further, since a columnar body may be used as the material for forming the reinforcing layer 4, there is no need to process the material into a pipe shape, so that the cost of the Nb ₃ Sn-based superconducting wire can be reduced. In the above example, Nb ₃ S
Although an example in which the method for manufacturing a superconducting wire of the present invention is applied to the method for manufacturing an n-based superconducting wire has been described, the manufacturing method of the present invention is applied to Nb ₃ Sn, Nb ₃ Ga, Nb ₃ Ge, Nb ₃ Al, V
Needless to say, it may be applied to a method of manufacturing a superconducting wire such as ₃ Ga or Nb-Ti.

[0015]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to only these Examples. (Example 1) An Nb-1.2 wt% Ti rod having a diameter of 14 mm and an outer diameter of 25 m made of a Cu-13 wt% Sn alloy
m, insert into a tube with an inner diameter of 15 mm, reduce the diameter to 1.0
A 0 mm composite was obtained. Next, 91 of the composites were collected and inserted into a tube body made of Cu-8 wt% Sn alloy and having an outer diameter of 12 mm and an inner diameter of 11 mm, and the diameter was reduced to 1.1.
A 4 mm primary strand was obtained. Then, the primary strand is
Main assembly, outer diameter 13m made of Cu-8wt% Sn alloy
A secondary assembly line having a diameter of 11 mm was produced by inserting the tube into a tube having an inner diameter of 12 mm and an inner diameter of 12 mm and performing a diameter reduction process.

Next, a diffusion prevention tube made of Ta is covered on the outside of the secondary assembly line obtained in this manner, and then the outer circumference of the diffusion prevention tube is 2.45 mm along the longitudinal direction of the diffusion prevention tube. 18 columnar bodies made of Cu-20 wt% Nb are additionally provided, and the outer diameter is 19 m outside the columnar bodies.
m, an inner diameter of 18 mm was covered with Cu, and the entire diameter was reduced to 0.8 mm, and then diffusion heat treatment was performed by heating at 675 ° C. for 10 days.
A (Nb, Ti) ₃ Sn superconducting wire was obtained. The core portion of the superconducting wire thus obtained had a structure in which 8,281 (Nb, Ti) ₃ Sn superconducting filaments having a diameter of 3.4 μm were arranged inside a base made of a Cu—Sn alloy. .

(Example 2) An Nb rod having a diameter of 14 mm was made of a Cu-6 wt% Sn alloy and had an outer diameter of 25 mm and an inner diameter of 1
The composite was inserted into a 5 mm tube and reduced in diameter to obtain a composite having a diameter of 1.0 mm. Next, 91 of these composites were collected, and Cu-6w
It was inserted into a tube body having an outer diameter of 12 mm and an inner diameter of 11 mm made of a t% Sn alloy and subjected to a diameter reduction process to obtain a primary wire having a diameter of 1.7 mm. Then, gather 33 of these primary strands, and
Outer diameter 13 mm, inner diameter 12 made of u-6 wt% Sn alloy
It was inserted into a tubular body having a diameter of 10 mm and subjected to a diameter reduction process to produce a secondary assembly line having a diameter of 11 mm.

Then, a diffusion prevention tube made of Ta is covered on the outside of the secondary assembly line obtained in this way, and then the outer circumference of the diffusion prevention tube is extended along the longitudinal direction of the diffusion prevention tube.
Eighteen columnar bodies made of Cu-15 wt% Nb having a diameter of 2.4 mm are additionally provided, and an outer diameter of 19 m is provided outside these columnar bodies.
After covering with a coating tube made of Cu having an inner diameter of 18 mm and an inner diameter of 18 mm, the entire diameter was reduced to 0.5 mm, and then diffusion heat treatment was performed in the same manner as in Example 1 to obtain Cu-Nb / N.
A b ₃ Sn superconducting wire was obtained. The core portion of the superconducting wire obtained here has a diameter of 1.6 μ inside the base made of Cu—Sn alloy.
It had a structure in which 3,025 Nb ₃ Sn superconducting filaments of m were arranged.

(Comparative Example 1) A secondary assembly line was produced in the same manner as in Example 1. Then, a diffusion preventive tube made of Ta is covered on the outside of the secondary assembly line, and then Cu-20 wt having an outer diameter of 17 mm and an inner diameter of 12 mm is provided on the outer side of the diffusion preventive tube.
% Nb, and the outer surface of the reinforcing tube was covered with a coating tube made of Cu having an outer diameter of 19 mm and an inner diameter of 18 mm, and the entire diameter was reduced to 0.8 mm. By performing diffusion heat treatment in the same manner as
-Nb / was obtained (Nb, Ti) a ₃ Sn based superconducting wire. The core portion of the superconducting wire thus obtained has a diameter of 3.4 μm (Nb, Ti) ₃ inside a matrix made of Cu—Sn alloy.
The structure was such that 8,281 Sn superconducting filaments were arranged.

(Comparative Example 2) A secondary assembly line was produced in the same manner as in Example 1. Then, a diffusion prevention tube made of Ta was covered on the outside of the secondary assembly line, and a coating tube made of Cu having an inner diameter of 12 mm was further covered on the outside of the diffusion prevention tube to reduce the entire diameter to 0.8 mm. Thereafter, a diffusion heat treatment is performed in the same manner as in Example 1 above, so that Cu / (Nb, T
i) ₃ Sn superconducting wire was obtained. The core portion of the superconducting wire thus obtained has a structure in which 8,281 (Nb, Ti) ₃ Sn superconducting filaments having a diameter of 3.4 μm are arranged inside a matrix made of Cu—Sn alloy. there were.

(Comparative Example 3) A secondary assembly line was prepared in the same manner as in Example 2. Next, a diffusion prevention tube made of Ta is covered on the outside of the secondary assembly line, and then Cu-15 wt having an outer diameter of 17 mm and an inner diameter of 12 mm is provided on the outer side of the diffusion prevention tube.
% Nb, a reinforcing tube was covered, and further, a covering tube made of Cu having an outer diameter of 19 mm and an inner diameter of 18 mm was covered on the outer side of the reinforcing tube, and then the whole was reduced to a diameter of 0.5 mm. By performing diffusion heat treatment in the same manner as
It was obtained -Nb / Nb ₃ Sn superconducting wire. The core portion of the superconducting wire thus obtained has a structure in which 3,025 (Nb, Ti) ₃ Sn superconducting filaments having a diameter of 1.6 μm are arranged inside a matrix made of a Cu—Sn alloy. there were.

(Comparative Example 4) A secondary assembly line was prepared in the same manner as in Example 2. Then, a diffusion prevention tube made of Ta is covered on the outside of the secondary assembly line, and a cladding tube made of Cu having an inner diameter of 12 mm is covered on the outside of the diffusion prevention tube, and then the whole is reduced to a diameter of 0.5 mm. After calibrating, said Example 1
By performing diffusion heat treatment in the same manner as described above, Cu / Nb
₃ Sn superconducting wire was obtained. The core portion of the superconducting wire obtained in this manner has 3,02 Nb ₃ Sn superconducting filaments with a diameter of 1.6 μm inside the matrix made of Cu—Sn alloy.
It had a structure in which 5 pieces were arranged.

Next, in order to examine the superconducting properties of the superconducting wires of Examples 1 and 2 and Comparative Examples 1 to 4 manufactured as described above, the critical current density was measured in a magnetic field of 8 to 23T. . FIG. 3 shows the result. Further, in order to examine the mechanical properties of the superconducting wires of Examples 1 and 2 and Comparative Examples 1 to 4, room temperature and liquid nitrogen temperature (7
7K), 0.2 at liquid helium temperature (4.2K)
The% yield strength was measured. FIG. 4 shows the result.

As is clear from the results shown in FIGS. 3 to 4, the superconducting wires obtained in Examples 1 and 2 have the same degree as the superconducting wires of Comparative Examples 1 and 3 manufactured by the conventional manufacturing method. It can be seen that it has superconducting properties and further has mechanical properties comparable to those of the superconducting wires of Comparative Examples 1 and 3. Further, in the manufacturing methods of Examples 1 and 2, since it is not necessary to use a reinforcing pipe processed into a pipe shape as the reinforcing layer forming material, the superconducting wire can be easily manufactured. Therefore, Examples 1 to 1
According to the manufacturing method of No. 2, it was found that the superconducting wire can be easily manufactured without impairing the mechanical characteristics and the superconducting characteristics.

[0025]

As described above, the method of manufacturing a superconducting wire according to the present invention is characterized in that the core part made of an alloy-based superconductor or the core part provided with a material to be a superconductor by heat treatment has
Cu-Nb alloy, Cu-Al along the longitudinal direction of the core
Alloy, Cu-Ag alloy, a plurality of columnar bodies made of a reinforcing material are additionally provided, and a coating pipe made of a stabilizing material is covered on the outside of the columnar bodies, and then a diameter reducing process is performed. It is not necessary to use a reinforcing pipe that has been processed into a pipe shape as the reinforcing layer forming material, as long as the material for forming the reinforcing layer can be formed into a columnar shape with a metal having good mechanical properties, machinability and workability can be improved. It can be used even if it is bad. Further, since a columnar body may be used as the reinforcing layer forming material, the step of processing into a pipe shape is eliminated. Therefore, according to the present invention, there is an advantage that it is possible to provide a method for manufacturing a superconducting wire, which has a high degree of freedom in selecting a material that can be used as a material for forming a reinforcing layer and can reduce the cost.

[Brief description of drawings]

1A to 1G are cross-sectional views showing an example of a method for manufacturing a superconducting wire of the present invention in the order of steps.

FIG. 2 is a cross-sectional view showing an example of a method for manufacturing a superconducting wire of the present invention.

FIG. 3 is a graph showing the relationship between the magnetic field and the critical current density in each compound-based superconducting wire.

FIG. 4 is a graph showing the relationship between the temperature and 0.2% proof stress of each compound-based superconducting wire.

FIG. 5 is an enlarged cross-sectional view showing an example of an internal reinforcement stabilizing Nb ₃ Sn based superconducting wire.

6A to 6G are cross-sectional views showing, in the order of steps, a method for manufacturing a conventional internal reinforcement stabilizing Nb ₃ Sn based superconducting wire.

[Explanation of symbols]

1 ... Superconducting wire, 2 ... Core part, 3 ... Diffusion prevention layer, 4 ... Reinforcing layer, 5 ... Stabilizing layer, 42 ... Diffusion prevention tube, 43 ... Column Body, 44 ... cladding tube.

Front page continuation (72) Inventor Takashi Saito 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Ltd.

Claims (2)

[Claims] 1. A method of manufacturing a superconducting wire, wherein a reinforcing layer is provided on an outer periphery of a core portion made of an alloy-based superconductor or a core portion provided with a material to be a superconductor by heat treatment, and a stabilizing layer is further provided on the outer periphery. , Cu-Nb alloy, Cu-Al alloy, C on the outer periphery of the core along the longitudinal direction of the core.
A step of providing a plurality of columnar bodies made of a reinforcing material selected from among u-Ag alloys, covering the outer side of the columnar bodies with a coating tube made of a stabilizing material, and then performing a diameter reduction process. And a method for manufacturing a superconducting wire. 2. The method of manufacturing a superconducting wire according to claim 1, further comprising the step of forming a diffusion prevention layer between the core portion and a plurality of columnar bodies attached to the outer periphery of the core portion. Manufacturing method of superconducting wire.