JPS6113508A - Method of producing low copper ratio nb3sn superconductive wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for manufacturing a Nb, Sn superconducting wire with a low copper ratio.

(Technical background of the invention and its problems) Nb, Sn superconducting wires exhibiting good superconducting properties in high magnetic fields are generally manufactured by heat treating a ternary composite wire containing Nb5Sn and O. This is 1
This is because the direct reaction between Nb and 8N, which requires a high temperature of 000°C or higher, is reduced to about 600°C by using O as a diffusion path.

An internal diffusion method is known as a method for manufacturing such Nb5Sn superconducting wires.

In the internal diffusion method, O and O placed through a barrier are used.
A bronze method in which Nb is placed in a u-8n alloy matrix, and a pipe structure method in which an 8n or Sn-based alloy is placed in a Nb vibe placed in a Cu matrix via O (Japanese Patent Laid-Open No. 52-16997) There is a public notice), but
The former method requires a lot of intermediate annealing to work harden the bronze and has the disadvantage of complicating the process. This has advantages such as a high critical current density in the copper part of the valve.

In recent years, there has been a strong demand for miniaturization of superconducting equipment, and with this, there has been an urgent need to develop wire rods with a high current density (over all critical current density), that is, a low copper ratio.

In this case, although the pipe construction method has the above-mentioned advantages, compared to the bronze method, the copper ratio (
area ratio of the stabilized steel part to the part other than the stabilized copper)
It has the disadvantage that it is difficult to make it small.

In general, the minimum value of this copper ratio depends on the structure of the wire, but in the case of the pipe structure method for ultra-fine multi-core wires, the minimum value of the copper ratio is approximately 0.9 to 1.0.
On the other hand, in the case of bronze method, it is 0.2 to 0.3.

(Objective of the Invention) The present invention was made to solve the above-mentioned problems.
The object is to provide a method for easily manufacturing superconducting wires.

(Summary of the Invention) The method for manufacturing a low copper ratio Nhl Sn superconducting wire of the present invention includes (a) sequentially disposing a Cu-based metal layer, a Nb-based metal layer, and an O layer on the outer periphery of an Sn-based metal; (b) chemically removing the outermost layer of the wire; (c) a plurality of wire rods from which the Cu layer has been removed; It is characterized by the steps of filling books into a Cu tube, and then subjecting them to cold working and heat treatment.

In the present invention, it is preferable that the cold working for manufacturing the multi-filament wire is performed by hydrostatic extrusion, and in this case, the extrusion ratio is set to 4 or more in order to thoroughly bond the Nb in the outermost layer of the wire incorporated in the Cu tube. There is a need to.

Furthermore, since the outermost O layer is chemically removed during the manufacturing of the sindal wire, by arranging it as thin as possible, the process is simplified, and problems such as lubrication when the outermost layer is made of Nb can be avoided. can be avoided.

(Embodiment of the Invention) FIG. 1 is an enlarged cross-sectional view showing an embodiment of the Nb, Sn superconducting wire manufactured according to the present invention. S
It has a structure in which an Ou-Sn alloy 3 is arranged within the nu layer.

A multifilamentary wire having such a structure is manufactured according to the following steps.

Figure 2 shows the manufacturing process of single wire.
As shown in a), a Cu tube 5, an N
After the b-tube 6 and the Cu-tube 7 are coated in sequence, they are subjected to swaging and wire drawing to produce a wire rod 8 having a hexagonal cross section as shown in the same figure. The outermost layer of the Cu tube 7 of this wire is dissolved and removed with acid to obtain a single wire 9 shown in FIG. 3(C).

A large number of single wires 9 obtained in this way are
As shown in the figure, after filling Ou' 110, which becomes a stabilizing steel, and filling the gap between the Cu tube 10 and the single wire 9 with a filler 11 made of carbon-free copper, both ends of the Cu tube 10 are It is sealed using an electron beam and then subjected to isostatic extrusion. Furthermore, the extruded wire is subjected to wire drawing processing as required, and then heat treated at a temperature of 600 to 800°C to obtain a superconducting wire. ◎The cross section of part 1 of Figure 3 after heat treatment is shown in an enlarged view. Figure 1 shows this.

Specific exception diameter: 9.1 mm, inner diameter: 8. Nb in Cu tube of I Mφ
A tube, a Cu tube, and an 8n rod were sequentially inserted and cold worked to produce a wire rod having a hexagonal cross section with a distance between parallel surfaces of 2.26111111.

This wire was immersed in nitric acid to remove the outermost Cu portion, and 931 single wires were obtained, with an outer diameter of 80 mm and an inner diameter of 71 mm.
After filling into a Cu tube of mφ, the billet with both ends sealed was subjected to hydrostatic extrusion processing and extruded to an outer diameter of 38 mm. Next, wire drawing is performed to reduce the outer diameter to 1. After manufacturing the OMφ wire rod, it was heat-treated at 725° C. for 96 hours. The copper ratio of the obtained superconducting wire is 0.3 (filament diameter is 28 μ!!
1), the critical current density (over all) is 12〒 and 3
It was 85 A/-.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view showing one embodiment of the Nb38n superconducting wire manufactured according to the present invention, and FIGS. 2(a) to (C) show an example of the manufacturing process of the single wire used in the present invention. FIG. 3 is a cross-sectional view showing the filling state of a single wire in a Cu tube. 1-----m-----Nb3Sn layer 2----
−−−−−−−−− Nb matrix 3 −−−−−
-1--------Q u -8n alloy 4 ---
---------- Sn rod 5, 7.10-Ot
+ tube 6----------- N b tube 9 ---
-1-------- Single line Figure 1 Figure 3 Figure 2

Claims (1)

[Claims] (a) A process of sequentially arranging a Cu-based metal layer, a Nb-based metal layer, and a Cu layer on the outer periphery of a Sn-based metal, and manufacturing a wire rod having a hexagonal cross section by subjecting the layer to cross-section reduction processing. (b) chemically removing the outermost Cu layer of the wire; (c) filling a plurality of wires from which the Cu layer has been removed into a Cu tube, and then subjecting them to cold working and heat treatment. A method for producing a low copper ratio Nb_3Sn superconducting wire, comprising the steps of: