JPH05290655A - Manufacturing method of Nb3Sn superconducting wire - Google Patents

Abstract

(57) [Summary] [Purpose] Nb ₃ S with good quality and excellent superconducting properties.
An n superconducting wire manufacturing method is provided. [Structure] A Nb-made pipe 6 and a Cu-made pipe 14 are sequentially compounded on the outer periphery of a composite billet A in which Cu and Sn raw material powders are densely packed in a Cu-made pipe 4 to form a composite billet B. A large number of composite materials 5 obtained by stretching
In the manufacturing method of the Nb ₃ Sn superconducting wire, which is formed by filling the u-made pipe 24 into the metal composite billet 8 and subjecting the metal composite wire rod obtained by stretching the metal composite billet 8 to heat treatment, the Cu-made pipe 4 The Sn powder 3 in which Cu is plated on the Cu and Sn raw material powders to be filled therein is used. [Effect] Since the Sn powder 3 plated with Cu is used as the raw material powder filled in the Cu pipe 4, the surface of the raw material powder is homogenized, and the fluidity between the raw material powders is improved, so that the composite billets A and B and the metal composite are formed. The workability of the billet 8 is improved, and an Nb ₃ Sn superconducting wire having excellent quality and superconducting properties can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently producing Nb ₃ Sn superconducting wire which has good quality and excellent superconducting properties.

[0002]

2. Description of the Related Art A compound superconductor represented by the chemical formula of A ₃ B such as Nb ₃ Sn, V ₃ Ga, Nb ₃ Al is called an A 15 type compound superconductor, and its application research together with Nb-Ti alloy superconductor has been studied. It is being strongly promoted, and its practical application to magnetic levitation trains, high-energy particle accelerators, nuclear magnetic resonance imaging devices for medical diagnosis, etc. is rapidly expanding. by the way,
Since the compound superconductor described above is hard and brittle, it cannot be directly processed into a wire like an alloy material. Therefore, for example, a Cu-Sn alloy (bronze) pipe is filled with an Nb metal material to form a composite. A billet is formed, and this composite billet is drawn to form a composite wire rod having a desired shape. After that, the composite wire rod is subjected to a predetermined heat treatment to heat Sn in the Cu-Sn alloy pipe material to an Nb metal material. It is manufactured by a bronze method or the like in which the Nb ₃ Sn superconductor phase is diffused to react and generate. However, in the above-mentioned bronze method, the Cu-Sn alloy, which is the exterior of the composite billet, has a large work hardening amount, and therefore, it is necessary to perform intermediate annealing many times during the drawing process, resulting in poor productivity.

[0003]

From the above,
A metal composite billet made of a metal material having good workability such as Cu, Nb, and Sn is produced, and the metal composite billet is drawn into a wire rod having a desired shape without annealing in the middle, and the wire rod is subjected to the final step in the above step. Nb ₃ S
An internal diffusion method has been proposed in which an n-superconductor phase is generated by reaction. In this internal diffusion method, the raw material Sn is made into powder, Cu powder is mixed with this powder, and this mixed raw material powder is made into Cu.
It is filled into a pipe to form a composite billet, and an Nb pipe and a Cu pipe are sequentially composited on the outer periphery of the composite billet, and a large number of composite wire rods obtained by drawing and processing are filled in the Cu pipe to form a metal. This is a method of producing a Nb ₃ Sn superconducting wire by forming a composite billet, drawing the metal composite billet to form a metal composite wire, and subjecting the metal composite wire to a predetermined heat treatment. In addition, the Sn powder filled in the Cu pipe is
The powder is mixed in such a manner that the Sn powder Sn and the Nb pipe Nb react with the Nb ₃ Sn superconductor phase in the final heat treatment, and the Cu powder dispersed in the Sn powder has a catalytic action. This is because it accelerates the reaction rate. However, in this internal diffusion method, in the drawing step, the deformability of the raw material powder of the Cu powder and the Sn powder inside is low, the bellows-like entanglement occurs in the processed wire, and the target thin wire cannot be processed. Even if the superconducting wire can be processed, there is a problem that the superconducting wire is inferior in superconducting property.

[0004]

The present invention has conducted intensive studies in view of the above situation, and the deformability of the raw material powder layer obtained by mixing Cu powder and Sn powder is low because the flowability of Cu powder and Sn powder is low. It was discovered that this is due to differences in sex, and further research was conducted to complete the present invention. That is, in the present invention, a Nb-made pipe and a Cu-made pipe are sequentially compounded on the outer periphery of a composite billet A in which a Cu-made pipe is filled with Cu and Sn raw material powders to form a composite billet B, and this composite billet B is drawn. Nb ₃ Sn superconducting wire in which a large number of composite wire rods obtained by applying the above are filled into a Cu pipe to form a metal composite billet, and the metal composite wire rod obtained by stretching the metal composite billet is subjected to a predetermined heat treatment. In the method for producing Nb ₃ Sn superconducting wire, the Sn-plated Cu powder is used as the raw material powder for Cu and Sn to be filled in the Cu pipe.

In the method of the present invention, the Sn powder is plated with Cu by an electroless plating method such as chemical plating or immersion plating, or an arbitrary method such as a vacuum deposition method. Further, it is preferable that the ratio of Cu to be plated on the Sn powder is 5 to 70 wt%, particularly 5 to 50 wt%, because good workability can be maintained. In the method of the present invention, in order to fill the Sn-plated Cu powder into the Cu pipe, a method is generally used in which the powder is tapped and then compression-molded by swaging. The Cu-plated Sn powder may be compressed and then filled into the Cu pipe. However, when a plurality of the compression-molded bodies are filled, when the composite billet is stretched, the boundary portion of the compression-molded body is It is not preferable because the composite wire or the like may be twisted or broken in a discontinuous state.

The present invention will be specifically described below with reference to the drawings. 1A to 1E are process explanatory views showing an example of a method of producing a metal composite billet used in the present invention. Cu is plated on Sn powder 1 to form Cu plating layer 2 on Sn powder 1.
Cu-plated Sn powder 3 coated with is prepared (Fig. A),
This Cu-plated Sn powder 3 is filled into a Cu pipe 4 to form a composite billet A (Fig. B), and the composite billet A is swaged to increase the packing density of the Cu-plated Sn powder 3 into a composite material 5. The Nb-made pipe 6 and the Cu-made pipe 14 are sequentially coated to form a composite billet B (Fig. C). The composite billet B is sequentially subjected to swaging, drawing and drawing to form a hexagonal wire 7 ( (Fig. 2) Next, this hexagonal wire 7
Is densely packed in a Cu pipe 24 to produce a metal composite billet 8 (Fig. E).

In the method of the present invention, the Cu-plated Sn powder is not directly put into the Nb-made pipe, but the Cu-made pipe is interposed. In the heat treatment in the final step, the Cu-made pipe plays a catalytic action and Nb ₃ This is for promoting reaction generation of the Sn superconductor phase. The method of the present invention is a super-multicore superconducting method in which a large number of metal composite wire rods obtained by drawing a metal composite billet are filled in a Cu tube again to form a metal composite billet, and the drawing process is performed a desired number of times. It can also be applied to the production of wires.

[0008]

According to the method of the present invention, the Nb-made pipe and the C-made pipe are provided on the outer periphery of the composite billet A in which the Cu and Sn raw material powders are filled in the Cu-made pipe.
u pipes are sequentially compounded to form a composite billet B, and a large number of composite wire rods obtained by subjecting the composite billet B to a drawing process are filled into a Cu pipe to form a metal composite billet, and the metal composite billet is drawn. In a method for producing a Nb ₃ Sn superconducting wire by subjecting a metal composite wire obtained by processing to a predetermined heat treatment, Cu and Sn filled in a Cu pipe are used.
Since the Cu-plated Sn powder is used as the raw material powder, the surface of the raw material powder is homogenized, and as a result, the deformability of the raw material powder layer is made uniform and the workability of the composite billet and the metal composite billet is improved, and the quality and superconductivity are improved. Nb ₃ S with excellent characteristics
n superconducting wire is obtained.

[0009]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 An Sn powder having an average particle size of 10 μm was plated with Cu by an electroless plating method to prepare a Cu-plated Sn powder, which was then used for the inner diameter.
After filling a pure Cu pipe having a diameter of 27 mmφ and an outer diameter of 30 mmφ, both ends of the Cu pipe were vacuum-sealed at 0.001 Torr by electron beam welding to produce a composite billet A. Next, this composite billet A was swaged to form a 10 mmφ composite material in which the Cu-plated Sn powder layer inside was densified, and an Nb pipe with an inside diameter of 10.1 mmφ and an outside diameter of 14 mmφ and an inside diameter of 14.1 was formed on the outer periphery of this composite material. A hexagonal wire rod with a hexagonal cross section of 1.9 mm on the opposite side is formed by compounding a Cu pipe with mmφ and an outer diameter of 18 mmφ to form a composite billet B, which is then swaged to 8 mmφ, and then drawn and drawn. I said. Next, 37 hexagonal wire rods were filled in a pure Cu pipe having an inner shape of 14 mmφ and an outer diameter of 18 mmφ, and both ends of the pure Cu pipe were subjected to electron beam welding.
Vacuum-sealed at 0.001 Torr to produce a metal composite billet, and then this metal composite billet was subjected to swaging and drawing processes in order to form a 0.5 mmφ metal composite wire. In a gas atmosphere
After heat treatment at 750 ° C. for 200 hours, Sn of Sn powder plated with Cu and Nb of Nb tube are reacted to generate a superconductor phase of Nb ₃ Sn in a Cu matrix, and Nb ₃ An Sn superconducting wire was manufactured. Sn powder C
The u plating thickness was variously changed.

Comparative Example 1 An average particle size of 10 μ was placed in a pure Cu circular tube having an inner diameter of 27 mm and an outer diameter of 30 mm.
A 0.5 mmφ Nb ₃ Sn superconducting wire was manufactured by the same method as in Example 1 except that a composite billet A was prepared by tapping and filling a mixed powder of Cu powder and Sn powder of m. Comparative Example 2 In Comparative Example 1, a mixed powder of Cu powder and Sn powder having an average particle diameter of 10 μm was press-compressed into a pure Cu cylindrical tube having an inner diameter of 27 mm and an outer diameter of 30 mm to obtain a green compact having a diameter of 27 mm. A 0.5 mmφ Nb ₃ Sn superconducting wire was manufactured by the same method as in Comparative Example 1 except that five compacts were densely packed so that there was no gap between them. The critical current density (Jc) of each Nb ₃ Sn superconducting wire thus obtained was measured in liquid He (4.2 K) under various magnetic fields. The results are shown in Table 1.

[0011]

[Table 1]

As is clear from Table 1, the method products of the present invention (Nos. 1 to 5) obtained high Jc values even under a high magnetic field. The ratio of Cu in the Cu-plated Sn powder is 10-30wt
The highest value was shown in%. In the case of more than 50 wt% (No. 5), Jc was slightly lowered. On the other hand, No. 6 of the comparative example product uses a mixed powder of Cu and Sn as the raw material powder, so the deformability of the raw material powder is reduced, and the hexagonal wire, that is, the filament, inside the Jc
Has dropped considerably. In No. 7, since the compression molded product of the above-mentioned mixed powder was used as the raw material powder, the metal composite billet was discontinuously deformed at the joints of the compression molded product, and the processed wire rod was twisted, resulting in 2 to 4 mmφ. There were many disconnections. Although the multi-core Nb ₃ Sn superconducting wire having 37 cores has been described above, in the method of the present invention, the multi-core Nb ₃ Sn superconducting wire is repeatedly filled with a large number of the above-mentioned metal composite wire rods in a Cu pipe and stretched. Even when applied to the manufacture of superconducting wires, N with the same high quality and high superconducting characteristics
A b ₃ Sn superconducting wire is obtained.

[0013]

As described above, according to the method of the present invention, an Nb ₃ Sn superconducting wire having good quality and excellent superconducting properties can be efficiently produced, and has a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing an embodiment of a method for producing a metal composite billet used in the present invention.

[Explanation of symbols]

 1 Sn powder 2 Cu plating layer 3 Cu plating Sn powder 4,14,24 Cu pipe 5 Composite material 6 Nb pipe 7 Hexagonal wire 8 Metal composite billet A, B composite billet

Claims (1)

[Claims] 1. A composite billet B in which a Cu-made tube is filled with raw material powders of Cu and Sn and a Nb-made tube and a Cu-made tube are sequentially combined on the outer periphery of the composite billet A to form a composite billet B.
Nb _{3 in} which a large number of composite wire rods obtained by subjecting the metal composite wire rods obtained by subjecting the metal composite wire rods to a metal composite billet are obtained by subjecting the metal composite billet to a stretch treatment. In the method for manufacturing an Sn superconducting wire, the raw material powder of Cu and Sn to be filled in the Cu pipe is C
Nb characterized by using Sn powder plated with u
₃ Sn superconducting wire manufacturing method.