JPH0717992B2 - Nb (bottom 3) Method for manufacturing Sn multicore superconducting wire - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing a superconducting wire, and more particularly to a method for manufacturing a Nb ₃ Sn multicore superconducting wire having a multicore structure by an internal diffusion method.

[Technical Background of the Invention] Conventionally, as a method for producing a Nb ₃ Sn superconducting wire having a multi-core structure, an internal diffusion method is known. In this method, Sn serving as a diffusion source and a large number of Nb wires are arranged in a Cu matrix, and Nb is applied by performing a two-step heat treatment after processing.
A Nb ₃ Sn layer is formed on the outer circumference or the entire line. Usually, stabilized Cu is arranged around the above Cu matrix through a diffusion barrier.

The above heat treatment is (1) heat treatment at less than 500 ° C for diffusing Sn in the Cu matrix (first-stage heat treatment)
And (2) 500 ° C or higher, normally 700 ° C, for Nb ₃ Sn formation
It is performed by the heat treatment before and after (heat treatment of the second stage),
Especially, the first stage heat treatment is usually performed from the temperature just above the melting point of Sn.
The heat treatment is performed stepwise within a temperature range below the reaction temperature for Nb ₃ Sn formation, and the heat treatment time is several days to ten and several days, depending on the diameter and arrangement of the Nb filaments. The reason why such a long-time heat treatment is required is that the heat treatment temperature is low and that the Sn diffusion path is limited to the Cu matrix in the Nb filament gaps that are close to each other.

[Problems of the Background Art] The internal diffusivity described above has an advantage that it is not necessary to perform intermediate annealing during processing, but it takes a long time to perform the diffusion heat treatment of Sn in the first step, and Sn is sufficiently homogeneous. If not,
In the heat treatment of the second stage, the formation of Nb ₃ Sn becomes insufficient, and there is a drawback that the superconducting property is deteriorated.

[Object of the Invention] The present invention has been made in order to solve the above-mentioned problems, and shortens the heat treatment time of the first step by dividing the Nb filament group into a plurality of Cu serving as Sn diffusion passages. At the same time, the purpose is to improve the superconducting properties after the second stage heat treatment.

[Summary of the Invention] The present invention assembles a plurality of composite wires in which a large number of Nb filaments are arranged in a Cu matrix on the outer periphery of a Sn or Sn alloy rod, and stabilizes them through a diffusion barrier. In a method for producing a superconducting wire by subjecting a composite housed therein to cross-section reduction processing, and then subjecting it to Sn diffusion heat treatment and Nb ₃ Sn formation heat treatment, the composite wire comprises a diffusion barrier and a Sn or Sn alloy rod. It is characterized in that the space between and is arranged in a space divided into a plurality by Cu.

The composite wire in the present invention is obtained by processing a Cu-coated Nb rod into a regular hexagonal cross section, accommodating a large number of the rods in a Cu tube, and further processing into a regular hexagonal cross section.

On the other hand, Sn or Sn alloy rods can use Cu-coated rods, and by having the same cross-sectional shape as the above composite wire, the Cu pipe in the state where multiple composite wires are closely attached to the outer periphery of any assembly. Can be filled inside.

[Embodiment of the Invention] An embodiment of the present invention will be described below.

[Example] FIG. 1 is a partial sectional view of a composite 1 used in the present invention, FIG. 2 is a sectional view of a composite wire 2 incorporated in the composite 1, and FIG. 3 is incorporated in the composite 1. 1 is a sectional view of a Cu-coated Sn rod 3, and a composite 1 was manufactured by the method described below.

As shown in Fig. 2, 931 Nb filaments 2b are arranged in a Cu matrix 2a, the copper ratio is 1.0, and the distance between parallel planes is 2.13 mm.
The composite wire 2 having a regular hexagonal cross section and the Sn rod 3a having the same cross-sectional shape as the composite wire 2 as shown in FIG.
A Cu-coated Sn rod 3 of 15 wt% Sn composition coated with Cu3b was manufactured by cold working. Furthermore, it has the same cross-sectional shape as the composite wire 2.
A Cu wire 4 is manufactured separately, and 174 of the composite wire 2 are arranged so as to be divided into 6 parts by the Cu wire 4 on the outer periphery where 127 of the Cu-coated Sn rods 3 are gathered. Then, the composite 1 was formed by accommodating it in a Cu pipe 6 having an outer diameter of 58 mmφ and an inner diameter of 46 mmφ.

This composite 1 is subjected to cross-section reduction processing such as swaging and wire drawing to obtain an outer diameter of 1.0 mmφ and a filament diameter of 0.9 μm.
φ, the number of filaments is 1443,000, after making it into a wire rod, 300 ℃ ×
3 days and 450 ℃ × 5 days Sn diffusion heat treatment,
Then, the Nb ₃ Sn superconducting wire having a multi-core structure was manufactured by subjecting Nb ₃ Sn to a heat treatment at 700 ° C for 60 hours. The critical current value of this superconducting wire was 60A at 9T.

[Comparative Example] Cu wire 4 arranged in the pipe of composite 1 in the example
Was replaced with a composite wire 2, and a composite body 7 shown in FIG. 4 having a structure in which a Cu diffusion path was not provided was subjected to the same processing method as in the example to obtain an outer diameter of 1.0 mmφ, a filament diameter of 0.9 μmφ, and a number of filaments of 16.095. After obtaining ten thousand wires, Sn diffusion heat treatment at 300 ℃ for 5 days and 45 ℃ for 10 days, then 700 ℃
A superconducting wire having a multi-core structure was manufactured by performing a heat treatment for Nb ₃ Sn formation for 60 hours. The critical current value of this superconducting wire is 46A at 9T.
Met.

[Effects of the Invention] As described above, according to the method for manufacturing a Nb ₃ Sn superconducting wire of the present invention, the Sn diffusion path made of Cu is provided in the wire having the final wire diameter before the heat treatment. , Sn diffusion heat treatment time can be greatly shortened, workability is excellent, and superconducting properties after heat treatment are improved.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a composite body used in the method of the present invention, and FIGS. 2 and 3 are sectional views of a composite wire and a Cu-coated Sn rod incorporated in the composite body, respectively. [FIG. 4] is a partial cross-sectional view of a composite body in a comparative example. 1, 7 ... Composite 2 ... Composite wire 3 ... Cu-coated Sn rod 4 ... Cu wire 5 ... Ta pipe 6 ... Cu pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuo Aoki Inventor No. 1-1 Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa 2-1-1, Showa Electric Cable Co., Ltd. (72) Tomoyuki Kumano 2 Sakae Oda, Kawasaki-ku, Kawasaki, Kanagawa No. 1-1 No. 1 Showa Electric Cable Co., Ltd.

Claims (4)

[Claims] 1. A plurality of composite wires in which a large number of Nb filaments are arranged in a Cu matrix are gathered around the outer circumference of a Sn or Sn alloy rod, and these are housed in a stabilized Cu tube through a diffusion barrier. In the method for producing a superconducting wire by subjecting a composite to a cross-section reduction process, and then subjecting it to a diffusion heat treatment of Sn and a heat treatment of Nb ₃ Sn generation, the composite wire comprises a diffusion barrier and a Sn or Sn alloy rod. Nb ₃ Sn characterized by being arranged in a space divided into multiple parts by Cu
Manufacturing method of multifilamentary superconducting wire. 2. The method for producing an Nb ₃ Sn multicore superconducting wire according to claim 1, wherein the Sn or Sn alloy rod is a Cu-coated rod. 3. Nb ₃ S according to claim 1 or 2, wherein a plurality of Sn or Sn alloy rods are assembled.
n Multi-core superconducting wire manufacturing method. 4. The method for producing an Nb ₃ Sn multi-core superconducting wire according to claim 1, wherein the diffusion barrier is made of Nb or Ta.