JPS6015090B2 - Compound superconducting wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stable compound-based superconducting wire without AC loss.

Most of the compound-based ultrafine multicore superconducting wires are made by compound-processing the constituent elements of the target compound superconducting material into the desired size and shape in the form of an easily processable alloy or single metal, and then heat-treating the material to cause the constituent elements to react with each other. It is obtained by producing a compound superconducting material.

To explain concretely by taking NCSn ultrafine multicore superconducting wire as an example, a composite wire is created by embedding a large number of Nb or Nb alloy pongee wires in a Cu-Sn alloy matrix, and then a final heat treatment is performed to form Nb or Nq alloy fine wires. An Nb3Sn layer, which is a reaction product of Nb and Sn in the matrix, is formed on the green surface. Similarly, in the case of the V30a ultrafine multifilament wire, the reaction between the Cu-Ga alloy matrix and the V pongee wire is carried out. Since an alloy with high electrical resistance is used in the matrix, there is a risk that the wire will burn out if the superconductor is quenched, that is, transferred from the superconductor to the normal conductor for some reason. As a protection method against this, a method using a high-purity stabilizing metal and a metal sequestration with low reactivity with it has been proposed. As shown in Fig. 1 using Nb and n as an example, a partition wall 3 made of Ta, Nb, etc. is provided between the Cu-Sn alloy 2 and the stabilizing high-purity Cu 4, and the heat treatment prevents the purity of 4 from decreasing. This is the way to do it. Although this method is effective for stabilization, when this wire is used in a pulsed magnetic field, it causes eddy current loss, which is undesirable. An object of the present invention is to provide a compound-based superconducting wire that is free from AC loss and is stable. According to the present invention, the purpose is to partially change the wall thickness of the partition wall in the circumferential direction, and to diffuse one of the components of the superconducting compound into the high-purity metal through the thin wall portion. This can be achieved by partially changing the high-purity metal into an alloy with high electrical resistance, and dividing the high-purity metal by the alloy portion and the partition wall. The first-stage composite, in which the target superconducting compound is produced by final heat treatment, is manufactured as follows.

In other words, it is a composite in which one of the constituent materials of a superconducting compound is embedded as a thin wire in an alloy containing other constituent materials, and a thick discontinuous partition wall is provided around this alloy to continuously surround it. A large number of these unit composites are individually buried in a stabilizing material made of high-purity metal, and the area-reduced composite is prepared before heat treatment, and the final heat treatment is performed to generate a superconducting compound. Through this heat treatment, the components in the alloy containing the constituent materials of the superconducting compound diffuse, forming superconducting compounds on the surface of the woven wire made of the constituent materials of the compound, and at the same time, diffusing to the partition wall side, forming thin parts of the partition wall. After passing through diffusion, it also diffuses into high-purity metals for stabilization and partially forms an alloy.

On the other hand, in the thick part of the partition wall, the components in the alloy cannot diffuse through the partition wall and reach the high-purity metal, so the high-purity metal facing the thick partition wall is not alloyed and becomes a high-purity metal. The metal is finely divided by the partition wall and the alloy part, that is, the high electrical resistance part. By further stabilizing the wire with such a high-purity metal and dividing the high-purity metal, it is possible to provide a wire that can eliminate loss in an alternating current magnetic field. Although the Nb3Sn compound superconducting material is used in the specific explanation of the present invention, the present invention is not limited to this, and V80a,
It can also be applied to N Hiroja, Nb3M, etc. FIGS. 1 and 2 show an example of a conventional compound superconducting wire, using N-based Sn as an example. In Fig. 1, 1 is an N curtain, 2 is a Cu-Sn alloy provided to surround the Nb wire, and 3 is a partition wall to prevent reaction between the Cu-Sn alloy and high-purity Cu4 for stabilization. .

After forming this shape and reducing the area, heat treatment is performed to react Sn and Nb in the Cu-Sn alloy to form Nb.
A compound layer of NCSn is generated on the wire surface.

At this time, the partition wall 3 prevents Sn from diffusing and contaminating the stabilizing high-purity Cu4. FIG. 2 shows another row of Nb3Sn compound superconducting wires in which a large number of Nb thin wires 1 are embedded as a matrix of Cu--Sn alloy 2.

Furthermore, the stabilizing high-purity Cu4 is surrounded by the partition wall 3 and buried therein. In this case as well, the final heat treatment results in Nb pongee wire 1
An NQSn layer is formed on the surface of the high purity Cu4, and the high purity Cu4 is not contaminated. In the secondary example shown in Figure 1, high-purity C for stabilization is used.
Although u is sufficient in quantity, it has the drawback of high eddy current loss when used in an alternating magnetic field. On the other hand, in the example shown in FIG. 2, the high purity Cu is divided, so the AC loss is small, but there are concerns about stability. The structure of the line village according to the present invention is shown in FIG.
As shown by taking an n-compound superconducting wire as an example, a Cu-Sn alloy 2 is surrounded by an Nb wire 1, and further Nb and T are continuously surrounded by a Cu-Sn alloy 2.
It consists of partition walls 3 having discontinuous thickness in the circumferential direction and stabilizing high-purity Cu4. After reducing the area to a predetermined wire diameter with this structure, if a final heat treatment is performed to form a Sn compound, Nb and Sn in the Cu-Sn alloy 2 will react to form Nb as shown in Figure 4. While a Sn compound layer is generated on the surface of the N-balance line 1, Sn in the Cu-Sn alloy 2 also reacts with the partition wall 3. For example, when the partition wall is Ta, Ta3Sn,
In the case of Nb, Nb3Sn is produced, but in the thinner parts of the partition wall 3, after the above reaction, Sn in the Cu-Sn alloy 2 further diffuses into the stabilized Cu4 to form a Cu-Sn diffusion layer 6. . This Cu--Sn diffusion layer 6 works to electrically divide the stabilized high-purity Cu 4 together with the partition wall 3, and can eliminate AC loss due to eddy current loss. Note that the partition wall 3 is made of Nb during the final heat treatment to form a compound layer.
The purpose can be achieved by configuring the wire 1 to have discontinuities in thickness in the circumferential direction, such as thicker parts and thinner parts than the thickness of the compound layer 5 to be generated on the surface of the wire 1. I can do it. To show an example of the method of manufacturing a wire rod according to the present invention, first, a CuSn alloy 2 is coated around an Nb wire 1 as shown in FIG. A composite material 9 is prepared which is entirely coated with high-purity Cu7. This composite material 9 has high purity C
This can be easily obtained by composite processing of a U-pipe, a partition wall material with discontinuous wall thickness, a Cu-Sn alloy pipe, and a Nb wire. Next, a large number of composite materials 9 in Fig. 5 are
It is inserted into the pipe 8, and the surface is machined to a predetermined line depression using a normal method, with an intermediate inscription added if necessary. By this processing, the high purity Cu around 9 and the pipe 8
The high-purity Cu adheres as if it were a body of Cu,
It can be shaped as shown in Figure 3. An example of manufacturing the wire of the present invention has been given, but in short, the present invention provides partition walls with discontinuous wall thickness in the circumferential direction, and in the final heat treatment, stabilization is achieved by the diffusion layer diffused from the discontinuous part of the partition wall and the partition wall. The purpose is to electrically divide high-purity metal to eliminate AC loss, and it goes without saying that it is not limited to the NGSn mentioned in the example. The partition wall with discontinuous wall thickness may or may not be made of the same material as 1 in Fig. 3, that is, one of the constituent materials of the target superconducting compound, but if it is made of the same material, the partition wall and the compound may be made of the same material. There is an advantage that a compound is generated on the surface in contact with other constituent materials, and the current capacity of the entire wire can be increased.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a compound superconducting wire according to the conventional method, FIG. 3 is a cross-sectional view of the wire according to the present invention before final heat treatment, FIG. 4 is a cross-sectional view after heat treatment, and FIGS. 5 and 6 The figure is a sectional view showing an example of the method for manufacturing the wire rod of the present invention. 1: Nb, 2: Cu-Sn alloy, 3: Partition wall, 4: High purity Cu for stabilization, 5: N wide Sn layer, 6: Cu-Sn diffusion layer, 7: High purity °C, 8: High purity Pipe, 9: Composite material. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1 A constituent material of a superconducting compound arranged so as to produce a superconducting compound by final heat treatment, a partition wall arranged so as to surround this constituent material and having a wall thickness varying in the circumferential direction, and a partition wall arranged so as to surround this partition wall. a stabilizing metal, the stabilizing metal being a product of the stabilizing metal and one of the constituents of the superconducting compound diffused into the stabilizing metal through the thin wall portion of the partition wall by a final heat treatment. A compound superconducting wire characterized by being divided by high electrical resistance parts.