JPS62243745A - Manufacture of superconductive electric wire containing dispersed fiber - Google Patents

Abstract

PURPOSE:To obtain a superconductive electric wire having a structure in which little strain is produced by mechanical stress by putting plated composite electric wires in a pipe, drawing down the pipe to the desired diameter and subjecting it to diffusion heat treatment. CONSTITUTION:An in situ rod 20 contg. many Nb fibers 21 dispersed and arranged closely in a matrix 22 is prepd. The rod 20 is drawn down under process annealing to form an in situ wire 20' and an Sn layer 23 is formed on the surface of the wire 20' by tinning to form a tinned composite wire 24. Several such wires 24 are assembled and put in a Cu pipe 25. This pipe 25 is covered with an Nb or Ta pipe 26 as a diffusion barrier and the pipe 26 is covered with a stabilizing pipe 27 of Cu or Al to form a composite pipe 28. This pipe 28 is drawn down and the resulting superconductive rough wire 29 is subjected to diffusion treatment to obtain a superconductive wire T.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for manufacturing a fiber-dispersed superconducting wire used in toroidal magnets for nuclear fusion reactors, magnets for particle accelerators, magnets for superconducting generators, and the like.

"Prior art" When a Cu-Nb-8na base alloy with a predetermined composition is melted,
It is possible to obtain an ingot which has a structure in which Nb dendrites are dispersed within a copper alloy matrix and which has high workability. If this ingot is subjected to strong processing such as wire drawing, it is possible to obtain in-situ rods in which a large number of Nb fibers are closely arranged and dispersed within the copper alloy base. -situ) method. Then, by subjecting the in-situ rod to diffusion heat treatment, the internal Sn and Nb are reacted to form a Nb*Sn superconducting intermetallic compound, thereby producing a fiber-dispersed superconducting wire portion.

By the way, the superconducting wire configured as described above has a small current capacity when used alone and requires a separate stabilizing material. A plaid type superconducting wire is produced by processing the wire as shown, attaching a stabilizing material, and making it plaid.

That is, in order to manufacture the plaid superconducting wire B shown in FIG. 2(E) using the in-situ rod I shown in FIG. 2(A), first, the in-situ rod I shown in FIG.
As shown in FIG. 2C, an in-situ wire 2 is produced by reducing the diameter to a desired diameter, and a Sn plating layer 3 is further formed on the outer surface of the in-situ wire 2 to produce a plated composite wire 4 shown in FIG. 2(C). Next, this plated composite wire 4 is subjected to diffusion heat treatment to generate a fibrous Nb, Snm conductive intermetallic compound inside the in-situ rod 1, thereby producing a fiber-dispersed Nb+Sn superconducting wire 5. Then, a plurality of superconducting wires 5 are arranged around stabilizing rods 6 made of Cu or AI, which serve as stabilizing materials, and fixed with solder to produce plaid-type superconducting wire B shown in FIG. 2(E). be.

On the other hand, conventionally, as shown in FIG.
Create a composite line IO by combining inside
As shown in FIG. 3, an in-situ rod 14 is arranged around a core material 13 made of Sn, and these are combined into a stabilizing material 11. A superconducting wire 16 is known in which the superconducting wire 16 is made of a composite material inside the 15th wire.

"Problems to be Solved by the Invention" However, when manufacturing a plaid superconducting wire having the structure shown in FIG. Because it is necessary to assemble the wires, fix them with solder, and form them into plaid, each superconducting wire 5 is subjected to mechanical stress during the plaiding process, causing strain in each superconducting wire 5, and this strain deteriorates the superconducting properties of each superconducting wire 5. There was a problem.

In addition, when superconducting wires 5 are arranged around the stabilizing rod 6 to form a plaid, there is a limit to the increase in capacity because there is a limit to the number of superconducting wires 5 that can be arranged around the stabilizing rod 6. There was such a problem.

By the way, when performing diffusion heat treatment on the plated composite wire 4 shown in FIG. 2(C), it is necessary to prevent the Sn plating layer 3 from melting down. For this reason, conventionally, during the diffusion heat treatment, S
Heat treatment is performed at a low temperature until Sn in the n-plated layer 3 diffuses into the ino-situ wire 2, and then Nb5S is applied at a high temperature.
It is necessary to perform diffusion heat treatment for n generation, which poses a problem that the heat treatment time becomes long.

On the other hand, the superconducting wire 12.16 with the structure shown in FIGS. 3 and 4
In this case, the core material 8 made of Sn is larger than the cross-sectional area of the wire.
．． Since the cross-sectional area ratio of 10 is large and voids are likely to be formed on the surface of the core material 8゜13 during diffusion heat treatment for producing superconducting intermetallic compounds, there is a problem that properties tend to deteriorate due to external forces during later machining. there were.

The present invention has been made in view of the above problem, and when manufacturing multi-core superconducting wires using in-situ rods, it is possible to prevent deterioration of superconducting properties that conventionally occurs due to mechanical stress during diameter reduction, and The purpose of the present invention is to provide a method for manufacturing a fiber-dispersed superconducting wire that can manufacture a superconducting wire with high capacity, shorten the processing time for diffusion heat treatment, and not create internal voids during the diffusion heat treatment. do.

"Means for Solving the Problems" In order to solve the above-mentioned problems, the present invention provides 2F! which constitutes a superconducting intermetallic compound! An in-situ rod is prepared in which ultrafine fibers made of at least one of the above metal elements are formed inside a base, and two or more metal elements constituting the intermetallic compound are coated on the surface of the in-situ rod. A plated composite wire is produced by forming a plated layer consisting of the remaining elements, and then a plurality of the plated composite wires are assembled to prevent diffusion of the elements constituting the superconducting intermetallic compound. After being inserted into a tube made of elements,
A stabilizing pipe is placed on the outside of this tubular body, and a diameter reduction process is performed to produce a superconducting strand of the desired diameter.Then, this superconducting strand is subjected to diffusion heat treatment to remove the elements constituting the plating layer. It diffuses and reacts with the elements constituting the ultrafine filaments to generate a superconducting intermetallic compound.

``Operation'' Because diffusion heat treatment is performed after inserting multiple plated composite wires inside the tube, diffusion heat treatment can be performed without performing low-temperature heat treatment to prevent melting of the plating layer.
In addition to shortening the heat treatment time, the Nb
In order to generate 5Sn, it is possible to increase the number of cores without applying strain due to mechanical stress to the superconducting wire, maintain good workability when reducing the diameter, and increase the number of plated composite wires that can be housed in the tube. It is possible to easily manufacture large-capacity superconducting wires by increasing the

"Example" Figures 1 (A) to (G) show an example of the present invention applied to the production of Nb3Sn superconducting wire.
By performing the processing shown in ~(G), the fiber-dispersed Nb5Sn superconducting wire T shown in FIG. 1(G) can be manufactured.

l) In order to manufacture the fiber-dispersed N bq S n super 7u conducting wire T, first, the in-situ rod 20 shown in FIG. 1(A) is manufactured. To manufacture this in-situ rod 20, a copper alloy base or a Cu-Nb-Sn ternary alloy or Cu-Sn alloy ingot having a structure in which Nb dendrites are dispersed in the copper base is melted, and a wire is attached to the ingot. It is manufactured by subjecting Nb dendrites to close contact in the form of fibers through drawing processing. This in-situ rod 20 has a large number of Nb fibers #C21 closely connected to the base 22.
This structure is well known in the art.

Next, while subjecting the in-situ rod 20 to an intermediate annealing treatment, the diameter is reduced to form an in-duration wire of 20° as shown in FIG. Then, a plated composite wire 24 shown in FIG. 1(C) was manufactured.

Next, the plated composite wire 24 is pulled together and then made of Cu-Sn alloy containing a low concentration of Sn or C
1 (D) as shown in FIG. Covering 1. Further, the tube body 26 is covered with a stabilizing pipe 27 made of Cu or A1 to produce a composite wire 28.

Next, the composite wire 28 is subjected to diameter reduction processing to produce a superconducting wire 29 shown in FIG. 1(F) having approximately the same diameter as the superconducting wire T to be manufactured.

In each of the diameter reduction steps described above, processing is performed in a state in which no Nb-Sn superconducting intermetallic compound is generated inside, and since the in-situ rod l has originally good workability, wire breakage etc. The diameter can be reduced without causing any trouble.

Then, the superconducting wire 29 is subjected to diffusion heat treatment (50%
The Nb fibers 21 and S
Sn in the n-plated layer 23 is reacted to generate N bi S n, thereby producing a fiber-dispersed Nb5Sn superconducting wire 'r shown in FIG. 1(G).

By carrying out the method explained above, fiber-dispersed Nt)+
When manufacturing Sn multicore superconducting wire T, plated composite wire 24
Since the Sn plating layer 23 is inserted into the pipe 25, there is no need to prevent the Sn plating layer 23 from melting during the diffusion heat treatment. In this respect, in the conventional method, in order to prevent the Sn plating layer from melting, it is necessary to diffuse the Sn plating layer inside the base by heating it at a low temperature for a long time before the diffusion heat treatment. However, in this example, the low-temperature heat treatment is no longer necessary, so the heat treatment time can be shortened. Let's change. In addition, since the amount of Sn contained in the superconducting wire T can be controlled by adjusting the thickness of the Sn plating layer 23, it is possible to manufacture a superconducting wire 'r containing a desired amount of Sn. .

In addition, in manufacturing the fiber-dispersed Nb*Sn superconducting IT, a large number of plated composite wires 24 are arranged inside the pipe 25, and after the diameter is reduced, diffusion heat treatment is performed, so that unlike the conventional plaiding method, Second, the number of plated composite wires 24 to be inserted into the pipe 25 can be arbitrarily selected, so that there is no need to perform machining after the superconducting intermetallic compound is formed and deterioration of the superconducting properties occurs. By inserting a large number of plated composite wires 24 into the wire 25, a large capacity superconducting wire can be manufactured. on the other hand,
Since the cross-sectional area of the Sn plating layer 24 formed on the outer periphery of the in-situ wire 2 is smaller than the cross-sectional area of the superconducting wire T, voids will not be generated by the diffusion heat treatment, and the deterioration of superconducting properties due to voids will be prevented. Does not occur.

By the way, in the above embodiment, an example in which the present invention was applied to the production of Nb5Sn superconducting wire was explained, but V+G
Of course, the present invention may be applied to other compound-based superconducting wires such as a. In addition, ■.

When producing a Ga superconducting wire, an in-situ rod is produced from a Cu-V-Sn ternary alloy ingot or a Cu-V alloy ingot, and then a composite rod and further a composite wire are sequentially produced using the in-situ rod. A plated composite wire is produced by applying Ga plating to the wire, and if necessary, a large number of plated composite wires are assembled and subjected to diffusion heat treatment to form V s Ga
It is possible to manufacture superconducting wires.

[Production Example IJ An in-situ rod with an outer diameter of 20 mm containing 30 wt% Nb is manufactured by an arc melting method, the surface layer is cut to remove impurities, and an in-situ rod with a diameter of 17 mm (1 = 17 mm) is manufactured. A pure Cu pipe with an outer diameter of 20 mm and an inner diameter of 18 mm was placed on the in-situ rod, and extrusion and wire drawing were performed to obtain a composite wire with a diameter II.

Next, this composite wire was electroplated with a S of 30μ thick.
A plated composite wire was produced by forming n plating layers. Next, 91 of the plated composite wires were assembled and inserted into a pipe having an outer diameter of 13 mm and an inner diameter of 12 mm and containing Sn6wL%, and an Nb pipe with an outer diameter of 15 mm and an inner diameter of 14 IllIIl to serve as a diffusion barrier was placed outside of the pipe. Then, a composite wire was produced by inserting it into a Cu pipe with an outer diameter of 20 mm and an inner fM l G mm, which served as a stabilizing material, and a diameter reduction process was performed on this composite wire to produce a superconducting wire with a diameter of 1fflI+1. did. Next, this superconducting strand is subjected to diffusion heat treatment in which it is heated to 550°C for 100 hours, and the Sn in the Sn plating layer is diffused into the inside of the in-situ rod to react with the Nb fibers inside the in-situ rod, forming an NbaSn superconducting intermetallic compound. Nb*Sn superconducting wire was produced.

The Nb, Sn superconducting wire manufactured as described above was subjected to an external magnetic field of 10 T (Tesla), a temperature of 4.2 K, and a critical current of 200 A.
In this case, a critical current density of 1000 A/im'' could be obtained, showing good characteristics.

"Effects of the Invention" As explained above, according to the present invention, the following effects are achieved.

(1) After inserting the plated composite wire into the tube, it is reduced in diameter until it reaches the desired diameter, and in order to be subjected to diffusion heat treatment later, in the diameter reduction process before diffusion heat treatment, Nb5Sn is added inside.
Processing can be performed without the generation of superconducting intermetallic compounds, and since in-situ rods inherently have good workability, diameter reduction processing can be performed without causing problems such as wire breakage, and mechanical A superconducting wire with a structure free from stress-induced distortion can be manufactured.

(2) Since any number of plated composite wires can be inserted into the tube, there is an effect that a large-capacity superconducting wire can be easily manufactured by increasing the number of plated composite wires to be inserted.

(3) In order to insert the plated composite wire inside the pipe, heat,
Melting of the Sn plating layer can be prevented from falling off during processing. Therefore, according to the method of the present invention, it becomes possible to omit the heat treatment at a low temperature that was conventionally performed to prevent dissolution of Sn before the diffusion heat treatment for Nb and Sn production, and the heat treatment time Let's make it shorter.

(4) The Sn compounded inside the superconducting wire is in the form of a plating layer, and the proportion of Sn to the cross-sectional area of the superconducting wire is small, so there is no possibility of voids occurring during diffusion heat treatment, and there is no risk of deterioration of mechanical properties due to voids. will not occur.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figures 1 (A) to (F') show an example of the method of the present invention. B) is a cross-sectional view showing the in-situ wire, Figure 1 (C) is a cross-sectional view showing the plated composite wire, and Figure 1 (D
) is a cross-sectional view showing the state in which the in-situ wires are assembled and inserted into the inside of the pipe, FIG. figure(
F) is a cross-sectional view of a superconducting wire, FIG. 1 CG) is a cross-sectional view of a superconducting wire, and FIGS. is a cross-sectional view of the in-situ rod, Figure 2 (B) is a cross-sectional view of the in-situ wire, Figure 2 (C) is a cross-sectional view of the plated composite wire, and Figure 2 (D) is a cross-sectional view of the superconducting wire. , FIG. 2(E) is a cross-sectional view of a plaid superconducting wire, FIG. 3 is a cross-sectional view showing one structure example of a conventional superconducting wire, and FIG. 4 is a cross-sectional view showing another structure example of a conventional superconducting wire. FIG. 'r...Superconducting wire, 20...In-situ rod, 21...
・Nb fiber, 22... Base, 25...
・・Pipe body, 26・・・・Pipe, 27°
゛... Stabilization pipe, 29... Superconducting wire. ↓ (G) ■/T Fig. 2 (8) 0-2 ↓ ↓ (D) ■-5 ↓ Fig. 8

Claims (1)

[Claims] An in-situ rod is prepared in which ultrafine fibers made of at least one element among two or more metal elements constituting the superconducting intermetallic compound are formed inside a base, and the intermetallic compound is formed on the surface of the in-situ rod. A plated composite wire is produced by forming a plated layer consisting of the remaining element among the two or more metal elements constituting the superconducting intermetallic compound, and then a plurality of the plated composite wires are assembled, and these are combined with the superconducting intermetallic compound. After inserting the superconducting wire into a tube made of an element that prevents the diffusion of the elements constituting the tube, a stabilizing pipe is placed on the outside of the tube, and a diameter reduction process is performed to produce a superconducting wire of the desired diameter. A fiber-dispersed superconducting wire characterized in that the superconducting wire is then subjected to diffusion heat treatment to diffuse the elements constituting the plating layer and react with the elements constituting the ultrafine fibers to generate a superconducting intermetallic compound. manufacturing method.