JP2006339041A - Manufacturing method of nb3sn superconductive wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a superconductive wire wherein the composite manufacturing method of the Nb3Sn superconductive wire is stabilized so that breaking of composite wire can be effectively prevented, its material cost can be reduced, and its assembling method can be simplified. <P>SOLUTION: In this manufacturing method of the Nb3Sn superconductive wire in which the periphery of a composite wire formed by assembling and bundling a plurality of composite module wires comprising a superconductive composite material containing three kinds of material of Nb or Nb based alloy, Cu or Cu based alloy, and Sn or Sn based alloy compounded in them are surrounded by a Sn diffusion preventing barrier material, a stabilizing material is then disposed around it to assemble a composit structural body, and after that, drawing process is applied to it, a thin copper tube made of Cu or a Cu based alloy material is interposed between the composite wire and the Sn diffusion preventing barrier material to assemble the composite structural body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a Nb3Sn compound superconducting wire used for, for example, a coil for a superconducting magnet.

A conventional method for producing a Nb3Sn superconducting wire is generally a method in which an Nb composite billet is processed into a composite wire having a predetermined shape and then subjected to a predetermined heat treatment to form an Nb3Sn phase. The method using a welded Ta tube manufactured by welding a Ta strip for preventing Sn diffusion to the outer periphery of the Nb wire and forming a butt portion of the rounded edge with a forming roll, and a Cu strip on the Ta strip. Manufactured by using a tube rolled into a cylindrical shape with a forming roll and incorporating a barrier material for diffusion prevention into the outer periphery of the composite module wire, and by drilling a hole in a Ta bar. There is a method of incorporating a seamless Ta tube into the outer periphery of the composite module wire as a barrier material for preventing Sn diffusion. (For example, see Patent Document 1)

Japanese Patent Laid-Open No. 10-69823 (FIG. 2)

Thus, according to the conventional method for manufacturing a Nb3Sn superconducting wire, for example, a Ta strip rolled with a forming roll and welded at its edge is incorporated into a composite billet as a barrier for Sn diffusion prevention. The plastic working during extrusion or drawing, the hardness of the welded portion of this Ta tube is high, and distortion due to welding is very unstable, so there is a problem that plastic deformation during processing becomes large and breaks. is there.
In addition, regarding a method of using a tube obtained by laminating a Cu strip on a Ta strip and forming a clad plate into a cylindrical shape with a molding roll as a barrier material for Sn diffusion prevention, There was a defect that air and impurities were involved between Ta and Cu strips.
In addition, in the distraction process after the composite, the inner edge of the roll-shaped tube moves freely while being constricted in a spiral shape at the same time as the distraction process. The edge is caught in the aligned groove of the composite module wire, and several composite module wire rods are pushed away and the composite wires cross each other. There are drawbacks.
Further, since the clad plate is a tube formed in a roll shape and rounded into a cylindrical shape, a Cu portion is formed at a place where the edge ends overlap, so the performance as a barrier material for preventing Sn diffusion is reduced and Sn diffusion treatment is performed. There is a drawback that Sn leakage occurs and there is a problem in that the Nb3Sn superconducting characteristics are deteriorated.
In addition, the seamless Ta tube manufactured by drawing or the like has a high cost for processing the seamless tube and is not suitable for mass production, and the material cost is nearly 40% of the entire Nb3Sn superconducting wire. There was a problem.

  The present invention has been made to solve the above-described problems, and stabilizes the composite manufacturing method of the Nb3Sn superconducting wire so as to effectively prevent the disconnection of the composite wire, thereby reducing the cost of the material and simplifying the assembly method. It aims at providing the manufacturing method of the Nb3Sn superconducting wire which can be formed.

  The present invention surrounds the periphery of a superconducting composite material including three types of materials of Nb or Nb-based alloy, Cu or Cu-based alloy, and Sn or Sn-based alloy composited therein, with a barrier material for preventing Sn diffusion, Furthermore, in the manufacturing method of the Nb3Sn superconducting wire in which a stabilizing member is arranged around these and the composite structure is assembled and then stretched, a Cu or Cu-based alloy is interposed between the composite wire and the Sn diffusion preventing barrier material. The structure is assembled by interposing a thin-walled copper tube made of a material.

  According to the manufacturing method of the Nb3Sn superconducting wire of the present invention, it is possible to effectively prevent the disconnection of the Nb3Sn composite wire, improve the yield and improve the superconducting performance, reduce the material cost and simplify the assembling method. Can be planned.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-section of a composite structure 5 constituting an Nb3Sn superconducting wire, and includes three types of materials: Nb or Nb-based alloy, Cu or Cu-based alloy, and Sn or Sn-based alloy compounded inside these Sn diffusion in which a thin copper tube 2 made of Cu or a Cu-based alloy material is arranged around a composite wire obtained by combining a plurality of composite module wires 1 made of a superconducting composite material, and a Ta plate is molded into a roll shape on the outside. The barrier material 3 for prevention is arrange | positioned, and also the stabilization copper pipe 4 is arrange | positioned on the outer periphery.

FIG. 2 is a perspective view of the composite structure 5 constituting the Nb3Sn superconducting wire, showing the composite method. The composite module wire 1 is bundled in 61 modules, and the outer diameter of the superconducting module wire is the entire composite structure 5. A composite wire having a cross-sectional area ratio of 45% is formed, and this composite wire is further combined into a thin copper tube 2 having a thickness of 1.6% for the composite body 5 to stabilize it. A composite structure 5 is obtained by incorporating the Sn diffusion preventing barrier material 3 formed by rolling a pure Ta plate into a roll inside the copper tube 4.
As described above, the Nb3Sn superconducting wire in which the thin copper tube 2 is arranged inside the Sn diffusion preventing barrier material 3 and the stabilized copper tube material 4 is arranged outside is configured, so that the clearance of the entire composite structure 5 is as much as possible. Can be small.

  And this composite structure 5 is closely_contact | adhered by cold drawing, and a Nb3Sn superconducting wire is obtained. In this case, the edge portion of the Sn diffusion prevention barrier material 3 in a state of being rounded by a forming roll is squeezed inward as a behavior in a drawing process after the Sn diffusion prevention barrier material 3 is made into the composite structure 5. However, since the inner edge of the thin copper tube 2 is present, there is no contact with the composite module wire 1 and it is processed while sliding on the outer diameter side of the thin copper tube 2. It is possible to prevent the composite wire from collapsing and the buckling breakage due to the cause of being caught in one alignment groove.

  In addition, the said thin-walled copper tube 2 is obtained by the drawing method which manufactured the material which pierced the pure copper rod, and used the draw bench. For example, a pure copper material having an outer diameter of 50 mm, an inner diameter of 30 mm, and a length of 1 m is manufactured and repeatedly stretched a plurality of times by a drawing die and a plug, but the copper material is used to achieve a thickness below the copper tube thickness limit that can be produced by industrial drawing. A thin copper tube 2 having a thickness of 0.3 mm or less was obtained by fine adjustment of the drawing speed of the steel sheet and multistage drawing with a die and a plug.

FIG. 3 is a diagram showing the processing history of the Nb3Sn superconducting wire obtained by the method of the present invention and the conventional method. According to the present invention, the final wire diameter, which is the target wire diameter, is the composite structure 5 in which the thickness of the thin copper tube 2 disposed inside the Sn diffusion barrier material 3 is 1.6% or less in cross-sectional area ratio with respect to the composite structure Nb3Sn superconducting wire A obtained by drawing to a diameter of 0.8 mm and drawing. A composite structure in which a conventional copper clad Ta diffusion barrier produced by sandwiching a copper plate above and below a Ta plate and rolled into a tubular shape with a forming roll is packed with a composite module wire 1 equivalent to the above is used as the target wire diameter. The Nb3Sn superconducting wire B was processed to the same level.
FIG. 4 shows the results of measurement of critical current density and hysteresis loss after the Nb3Sn superconducting wires A and B were subjected to Nb3Sn heat treatment in an inert gas atmosphere at a temperature of 650 ° C. for 240 hours. .
As can be seen from the results of FIGS. 3 and 4, the Nb3Sn superconducting wire according to the manufacturing method of the present invention exhibits excellent workability without disconnection or damage to the diffusion barrier material Ta in the drawing process, and has an excellent critical current density and It is clear that hysteresis loss is exhibited.
Therefore, in order to obtain such a superconducting Nb3Sn superconducting wire, it is preferable to suppress the thickness of the thin copper tube 2 to 1.6% or less with respect to the cross-sectional area ratio of the composite structure 5.

Further, FIG. 5 shows that the thickness of the thin-walled copper tube 2 disposed inside the Sn diffusion barrier material 3 by the manufacturing method of the present invention has a cross-sectional area ratio with respect to the composite structure 5 in the range of 1.3 to 1.6%. The result of having measured the field current density of the Nb3Sn superconducting wire about the case where it sets, and the case where the said cross-sectional area ratio is set to the range of 2.0-3.8% for comparison with this is shown.
This result also shows that it is preferable to suppress the thickness of the thin copper tube 2 to 1.6% or less with respect to the cross-sectional area ratio of the composite structure 5 in order to obtain an Nb3Sn superconducting wire having excellent superconducting characteristics.

It is sectional drawing of the composite structure which shows Embodiment 1 of this invention. It is a perspective view of the composite structure which shows Embodiment 1 of this invention. It is a figure which compares and shows the process log | history of the Nb3Sn superconducting wire obtained by this invention method and the conventional method. It is a figure which compares and shows the critical current density and the hysteresis loss data in the strong magnetic field of the Nb3Sn superconducting wire obtained by this invention method and the conventional method. It is a figure which compares and shows the data of the critical current density at the time of changing the thickness cross-sectional area ratio of the thin copper tube with respect to a composite structure by this invention method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Composite module wire 2 Thin copper tube 3 Barrier material for Sn diffusion prevention 4 Stabilized copper tube material 5 Composite structure

Claims (3)

Around a composite wire that is focused by combining a plurality of composite module wires made of a superconducting composite material including three types of materials of Nb or Nb-based alloy, Cu or Cu-based alloy, and Sn or Sn-based alloy composited inside these. In a method for manufacturing a Nb3Sn superconducting wire, which is surrounded by a barrier material for preventing Sn diffusion, and further, a stabilizing member is arranged around these parts, a composite structure is assembled, and then this is stretched.
A method of manufacturing an Nb3Sn superconducting wire, wherein the composite structure is assembled by interposing a thin copper tube made of Cu or a Cu-based alloy material between the composite wire and the Sn diffusion preventing barrier material. .   The method for producing a Nb3Sn superconducting wire, wherein the thin copper tube is set to a thickness corresponding to a cross-sectional area ratio of 1.6% or less with respect to the entire composite structure.   The method for producing a Nb3Sn superconducting wire, wherein the thin-walled copper tube is produced by producing a material in which a hole is made in a pure copper rod and drawing it using a draw bench.

Images