JPH0143409B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a compound superconducting wire in which a multicore compound superconductor layer is formed.

Conventionally, as a manufacturing method for compound superconducting wires, for example, the so-called bronze method shown in FIGS. 1 to 3 has been used, and here, the case of manufacturing a Nb ₃ Sn compound superconductor will be described.

() After plating the surface of rectangular rod-shaped Nb1 with Sn2 as shown in Figure 1A, this composite 3 is subjected to diffusion heat treatment to coat the surface with Nb ₃ Sn as shown in Figure 1B.
A method of forming a compound superconductor layer 4 and further plating or bonding a stabilizing metal 5 as shown in FIG.

() As shown in Fig. 2A, a composite 3 in which multiple Nb1 particles are embedded in a Cu-Sn alloy rod 6 is constructed as shown in Fig. 2B.
As shown in the figure, diffusion heat treatment is applied to the area around Nb1.
A method of forming a Nb ₃ Sn compound superconductor layer 4.

() As shown in Fig. 3A, a composite body 3 in which a plurality of Nb 1 are embedded in a Cu-Sn alloy rod 6 and a stabilizing metal 5 is provided on the outside via a partition material 7 such as Nb or Ta is subjected to diffusion heat treatment. As shown in Figure B, Nb
1. A method of forming a Nb ₃ Sn compound superconductor layer 4 around the Nb 3 Sn compound superconductor layer 4.

However, in the method shown in Figure 1, the base material
A single Nb ₃ Sn compound superconductor layer 4 on the surface of Nb1
As a result, a current distribution occurs in the width direction, and there is anisotropy with respect to the direction of the applied magnetic field, making it impossible to create a highly homogeneous magnet. Furthermore, since this compound superconducting wire 8 is a so-called single core wire, it cannot satisfy essential stabilization conditions, and an easy-to-use magnet cannot be obtained.

Furthermore, the bronze method shown in FIGS. 2 and 3 has a complicated structure, so that filament breakage is likely to occur. In addition, because the amount of Sn in the Cu-Sn alloy is limited, the Nb ₃ Sn compound superconductor layer 4 that is generated is not sufficient, and the Cu-Sn alloy that ultimately remains does not affect the characteristics of the superelectric wire 8. Critical current value (I _c )
There is a problem that the value becomes low. Particularly, as shown in Fig. 3, there is a risk that the partition wall material 7 will be broken during processing, and if it is subjected to diffusion heat treatment in this state, it will become a defective material, and the partition wall material 7 is irrelevant to the properties. , the characteristics deteriorated accordingly, and there were also drawbacks such as the inability to supply Sn2 from the outside.

As a result of conducting various studies in view of the above points, the present invention has been developed by dividing the compound superconductor layer formed on the surface of a single base material into a plurality of layers to form a multicore structure. We have discovered a method for manufacturing a compound superconducting wire that achieves essential stability and uniformity of current distribution, improves critical current, and has excellent workability.

That is, in the method of the present invention, a plurality of slits are formed along the longitudinal direction at predetermined intervals along the circumferential direction on the surface of a rod-shaped metal having a high melting point among the elements forming the compound superconductor. After fitting the partition material consisting of a non-contributing metal strip into the slit, it is inserted into a metal tube containing the other element with a lower melting point that forms a compound superconductor, and then after sealing both ends of this composite, a reduction The method is characterized in that the surface is processed into a desired shape, and then heat treated to form compound superconductor layers isolated in a multicore manner by the partition material.

The present invention will be explained in detail below with reference to the drawings.

FIG. 4 shows one method of the present invention for manufacturing a Nb ₃ Sn compound superconducting wire.

As shown in Figure 4A, among the elements that form the Nb ₃ Sn compound superconductor, Nb1, which has a high melting point and has a round bar shape,
is prepared, and a plurality of slits 9 are formed along the longitudinal direction at predetermined intervals along the circumferential direction of this surface.

Next, as shown in Figure B, each slit 9 is
A partition wall material 10 consisting of strips is inserted. This partition wall material 1
0 indicates a metal strip that does not contribute to superconductivity, that is, an element that does not form a superconducting alloy or compound with other constituent elements through diffusion heat treatment, or an element that does not form a superconducting compound under the conditions in which it is used. It is an alloy or compound that does not exhibit superconducting properties, and is not limited to the above-mentioned Ta strip, but may also be something like Ni strip.

As shown in FIG. 4C, the Nb1 in which the partition wall material 10 is fitted is made of Cu--Nb1, which contains Sn, which has a low melting point among the elements forming the _Nb3Sn compound superconductor.
Insert into Sn alloy tube 11. Next, this Cu−Sn
Both ends of the alloy tube 11 are covered with lids made of the same or different metals having approximately the same coefficient of thermal expansion, and are welded and sealed in a vacuum to form the composite body 3.

Next, this composite body 3 is compressed to form the shape D in the same figure.
As shown in FIG. 1, Nb1 and Cu-Sn alloy tube 11 are brought into close contact to prevent oxidation of the interface during heating.

Next, this composite body 3 is extruded and subjected to area reduction processing such as wire drawing to form a tape shape, rectangular shape, or round wire. In this case, area reduction processing is performed while appropriately performing intermediate annealing.

In addition, if the amount of Sn is insufficient, the surface of the composite body 3 which has been subjected to surface reduction processing may be plated with pure Sn as necessary.
The amount of Sn in the Cu-Sn alloy may be increased.

When the composite 3 is formed into a tape shape in this way, this composite 3 is then subjected to a diffusion heat treatment to form a superconducting Nb ₃ Sn compound between the Nb 1 and the Cu-Sn alloy 11a, as shown in Figure E. A body layer 4 is formed. In addition, if necessary, the surface may be further coated with a stabilizing metal such as Cu.
The Nb ₃ Sn compound superconducting wire 8 as shown in FIG. F is manufactured by bonding and bonding by plating or soldering.

The Nb ₃ Sn compound superconducting wire 8 thus obtained was formed as shown in the enlarged view in FIG.
The Nb ₃ Sn compound superconductor layer 4 is separated into a plurality of layers by a partition material 10 made of Ta strips. Although a reaction product 12 is formed on the surface of the partition wall material 10, this is harmless and does not contribute to superconductivity.

Therefore, since the compound superconductor layer 4 is formed in a multicore shape, essential stability can be obtained, and since the current distribution in the width direction can be made uniform, there is no anisotropy with respect to the magnetic field. When manufacturing, products with stable characteristics can be obtained. Furthermore, since the partition wall material 10 is provided perpendicularly to the compound superconductor layer 4 at intervals, surface loss can be reduced by several percent compared to the conventional method shown in FIG.
As a result, the critical current density can be improved, and Sn can be supplied from the outside, so the generated
The number of Nb ₃ Sn compound superconductor layers 4 can be increased, and as a result, the characteristics can be improved.

In addition, although Nb, which is the base material, is a single substance, a series of surface reduction processes are performed to form the Nb ₃ Sn compound superconductor layer 4.
Since it is possible to use multiple filaments, there is no breakage of the filament or tearing of the partition material 10, and the workability is extremely excellent compared to the conventional bronze method.

Note that the present invention is not limited to the method for manufacturing Nb ₃ Sn compound superconducting wires, but can also be applied to manufacturing compound superconducting wires formed by thermal diffusion between solid phases such as V ₃ Ga and Nb ₃ Al. Can be done. In addition,
When manufacturing a V ₃ Ga compound superconducting wire, V is used as a rod-shaped metal with a high melting point, and a Cu-Ga alloy tube, for example, is used as a metal tube containing an element with a low melting point. In addition, when manufacturing Nb ₃ Al compound superconducting wire, Nb is used as a rod-shaped metal with a high melting point, and metal tubes containing elements with a low melting point are made of, for example, Cu-Al.
Use alloy tubes, etc.

Next, specific examples of the present invention will be described.

As shown in Figure 4A, 47 slits 9 with a depth of 3 mm and a width of 1 mm are formed along the longitudinal direction at intervals of 10 mm on the surface of pure Nb1 with a diameter of 150 mm. A partition wall material 10 made of Ta strips was fitted and formed as shown in Figure B. Next, as shown in Fig.
-13.5% by weight Sn alloy tube 11, both ends of which were covered with Cu-13.5% by weight Sn alloy plates, and these were welded in a vacuum to seal the inside. Next, this composite 3 was heated at 700°C for 1 hour, and then extruded to an outer diameter of 25 mm to make the inside of the composite 3 adhere tightly.After that, intermediate annealing was performed every time the area reduction rate was 65%.
It was processed into a tape shape with a thickness of 100μ and a width of 5mm.

Next, the surface of this tape-shaped composite 3 was plated with dull Sn in an inert atmosphere and immediately subjected to diffusion heat treatment to increase the Sn content of the Cu-Sn alloy 11a in the surface layer. This was then subjected to diffusion heat treatment at 650°C for 80 hours to form Cu-Sn alloy 11a as shown in Figure E.
A multicore Nb ₃ Sn compound superconductor layer 4 isolated by a partition material 10 was formed at the interface with Nb1. Furthermore
F
A Nb ₃ Sn compound superconducting wire 8 as shown in FIG.

The current capacity of the compound superconducting wire 8 thus obtained was measured to be 12T (Tesler).
The current is 200A, and the variation in measurement of several samples is within ±5%. Also, the superconducting magnet created using this magnet has less anisotropy with respect to the magnetic field, so it has a higher homogenization of the magnetic field than conventional magnets. We were able to achieve this goal.

As explained above, according to the method for manufacturing a compound superconducting wire according to the present invention, the compound superconductor layer is divided into a plurality of layers by the partition material and formed into a multicore shape, thereby essentially stabilizing the superconducting properties and improving the current distribution. It is possible to achieve uniformity of the metal and obtain a high critical current, and it is also possible to form a multi-core shape by a series of surface reduction pressurization, so it has remarkable advantages such as superior workability compared to the conventional bronze method. It has a great effect.

[Brief explanation of drawings]

1 to 3 show the conventional method, and FIGS. 1A to 3C are cross-sectional views sequentially shown according to the steps of manufacturing a single-core compound superconducting wire, and FIGS. Figure B is a cross-sectional view showing the process of manufacturing a bronze-type compound superconducting wire, and Figures 3A and 3B are cross-sectional views showing the process of manufacturing a bronze-type compound superconducting wire provided with a stabilizing metal. cross-sectional view,
4A to 4F are cross-sectional views sequentially shown in steps of manufacturing a compound superconducting wire according to the method of the present invention, and FIG. 5 is a cross-sectional view showing an enlarged main part of FIG. 4F. 1...Nb, 2...Sn, 3...complex, 4...
Compound superconductor layer, 5... Stabilizing metal, 8... Compound superconducting wire, 9... Slit, 10... Partition material, 11... Cu-Sn alloy tube, 11a... Cu-Sn
alloy.

Claims (1)

[Scope of Claims] 1 A plurality of longitudinal slits are formed at predetermined intervals along the circumferential direction on the surface of a rod-shaped metal having a high melting point among the elements forming a compound superconductor, and superconducting action is achieved. After fitting a partition material made of a metal strip that does not contribute to A method for manufacturing a compound superconducting wire, which comprises reducing the area to a desired shape, and then heat-treating it to form a compound superconductor layer separated in a multicore manner by the partition material. 2. The method for producing a compound superconducting wire according to claim 1, which comprises heat-treating the composite material and then plating or bonding a stabilizing metal onto the surface of the composite material.