JPH04292809A - Multicore superconductive wire - Google Patents

Abstract

PURPOSE:To provide a multicore superconductive wire with resistance to deterioration of superconductive properties even in the case bending stress is applied. CONSTITUTION:A multicore superconductive wire is a wire composed of a plurality of superconductive parts consisting of oxide superconductive materials and put in a stabilizing material and is prepared by a method wherein a metal sheath to become the stabilizing material is filled with raw materials to become the superconductive parts, the resulting body is formed into a wire, and the collective body of the wires are bundled in a metal sheath to give a superconductive wire, and the final cross-section surface area of the superconductive parts is <=10% of the whole cross-section surface area of the wire.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a multicore superconducting wire using an oxide high-temperature superconducting material.

0002

2. Description of the Related Art In recent years, ceramic-based, ie, oxide-based superconductors have attracted attention as superconducting materials exhibiting higher critical temperatures. Among them, yttrium is 90K,
The bismuth type has a high critical temperature of about 110K, and the thallium type has a high critical temperature of about 120K, and their practical use is expected.

[0003] These high-temperature superconducting materials are considered to be applied to cables, busbars, power leads, coils, etc., and efforts are being made to increase the length of superconducting wires. Furthermore, similar to conventional metal-based and compound-based superconductors, the production of multifilamentary wires for these high-temperature superconductors is also being considered.

0004

[Problems to be Solved by the Invention] However, when a multicore superconducting wire using an oxide high-temperature superconducting material is applied to cables, coils, etc., there is a problem in that sufficient bending properties cannot be obtained.

An object of the present invention is to provide a multicore superconducting wire made of an oxide superconducting material having excellent bending properties.

[0006]

[Means for Solving the Problems] The multicore superconducting wire of the present invention is a multicore superconducting wire in which a plurality of superconducting parts made of an oxide superconducting material are arranged in a stabilizing material, and the raw material for the superconducting parts is This is a superconducting wire made by filling a metal sheath that serves as a stabilizing material and forming a wire rod, and then bundling this wire rod assembly in a metal sheath to form a wire rod, and the thickness of each superconductor part is equal to the total thickness of the wire rod. It is characterized by having a thickness of 10% or less.

The multicore superconducting wire of the present invention can be produced by, for example, coating powder of an oxide high-temperature superconductor or powder of a precursor with a metal sheath such as silver, making a round wire by wire drawing, and then manufacturing a large number of them. This can be obtained by gathering the material, covering it with a metal sheath such as silver, and wire-drawing it. If necessary, the wire may then be processed into a tape by compression processing such as rolling, or heat treated and sintered in the form of a round wire.

[0008]

Effects of the Invention Superconducting cables and coils, particularly superconducting cables, are subjected to bending stress during various processes and during installation. In the multicore superconducting wire of the present invention, a plurality of superconducting portions are arranged in a stabilizing material, and the thickness of each superconducting portion is 10% or less of the thickness of the entire wire. Therefore, even when subjected to bending stress, there is little deterioration in superconducting properties.

In the present invention, the reason why the thickness of each superconductor portion is set to 10% or less is that if it exceeds 10%, desired bending characteristics cannot be obtained. In this invention, more preferably, the thickness of each superconductor portion is 5% or less. By setting it to 5% or less, the bending characteristics can be further improved.

In the multicore superconducting wire of the present invention, metal-coated oxide superconductor wires serving as strands are assembled only once to form a multicore superconducting wire. Therefore, the distance between the superconductor parts is substantially uniform within the wire, and a good critical current density can be obtained.

[0011] The number of wire rods to be bundled as an aggregate is as follows:
In order to manufacture the oxide superconductor with normal dimensions and without making the proportion of oxide superconductor too small compared to the metal coating, 3.
0 or more is required.

Furthermore, the multicore superconducting wire according to the present invention is
In various steps, strain is controlled, preferably 0.3
% or less (strain=thickness of wire/bending diameter) is preferably used in processes such as winding and unwinding.

[0013] If the cyclic strain is controlled to a value of 0.3% or less, deterioration of superconducting properties can be prevented.

The multicore superconducting wire of the present invention is, for example, in the form of a tape-like wire, and after heat treatment, it is fed out, wound onto a reel or drum, and used as a cable or coil. It is preferable that the strain is 0.3% or less during winding and when used for various purposes.

The multicore superconducting wire of the present invention is preferably coated with metal from the viewpoint of stability. As for the type of metal, a metal with a low specific resistance that does not react with the high-temperature superconductor, has good workability, and functions as a stabilizing material is preferable; for example, silver and silver alloys are used.

[0016] These metallization layers may also be used as intermediate layers. When used as an intermediate layer,
Another metal such as copper, aluminum or an alloy thereof is further coated thereon.

[0017] As the high-temperature superconductor, for example, yttrium-based, bismuth-based, and thallium-based ones are used. Bismuth-based high-temperature superconductors are preferred because they have a low critical temperature, critical current density, low toxicity, and do not require rare earth elements.

In the multicore superconducting wire of the present invention, the thickness of each superconductor portion is 10% or less of the thickness of the entire wire. Therefore, the superconductor portion can be uniformly processed into fine filaments. For example, the superconductor portion can be made into a fine filament of 50 to several μm or less. Therefore, a multicore superconducting wire with excellent bending properties can be obtained.

Furthermore, in this invention, since the process of bundling the wire rod assembly in the metal sheath and forming the wire rod is performed only once, the distance between the superconducting parts is uniform inside the superconducting wire, and the distance between the superconducting parts is uniform. It can be processed into

[0020]

[Example] Example 1 Bi:Pb:Sr:Ca:Cu=1.84:0.36:
Oxides or carbonates were mixed to have a composition of 0.99:2.18:3.00. By heat treating this mixed powder, 85% of 2212 phase and 2223 phase as superconducting phase were obtained.
A powder having a phase content of 15% and consisting of a non-superconducting layer mainly composed of (Ca,Sr)2PbO4 and Ca2CuO3 was prepared. This powder was subjected to degassing treatment at 700° C. for 12 hours in a reduced pressure atmosphere of 10 torr.

[0021] These powders have an outer diameter of 12 mm and an inner diameter of 9 m.
The wire was covered with a silver pipe of 1.3 mm in diameter and wire-drawn to a diameter of 1.3 mm. 60 of these wires are further divided into outer diameter 16.5mm and inner diameter 1
It was placed in a 3.5 mm silver pipe and wire-drawn to a diameter of 1.0 mm. Thereafter, it was rolled to a thickness of 0.17 mm.

[0022] This wire rod was heat treated at 845°C for 55 hours and then rolled at a workability of 15%. The obtained tape-shaped wire rod was wound around a cylinder with an outer diameter of 50 mm, and heated at 840°C for 50 minutes.
Heat treatment was performed for 0 hours.

[0023] After this, it is paid out from this cylinder and has a diameter of 50 m.
It was wrapped around a Teflon pipe with a pitch of 80 mm. After repeating the bending in this state and with a radius of 100 mm 200 times, the critical current density was measured under liquid nitrogen. The critical current densities under liquid nitrogen are all stable; 14,
600 to 15,700 A/cm2. Thus, the wire rod of this example showed good characteristics even after sintering and subsequent bending.

Example 2 Bi:Pb:Sr:Ca:Cu=1.80:0.38:
Oxides or carbonates were mixed to have a composition of 2.00:1.97:3.00. This mixed powder was heat-treated to form a superconducting layer with 88% 2212 phase,
2223 phase is 12%, (Ca,Sr)2PbO
A powder consisting of a non-superconducting layer of Ca2CuO3 and Ca2CuO3 was prepared. This powder was subjected to degassing treatment at 700° C. for 18 hours in a reduced pressure atmosphere of 7 torr.

[0025] This powder was processed into wire rods in the same process as in Example 1, and 90 wire rods were assembled to produce a multifilamentary wire. This multifilamentary wire is drawn to a diameter of 2mm and then 0.25mm.
It was rolled to a thickness of . This wire rod was heat treated at 845° C. for 45 hours, and then rolled at a workability of 22%. This tape-shaped wire rod was heat-treated at 840° C. for 50 hours.

The obtained wire rod was bent 20 times with a radius of curvature of 50 mm and then returned to a straight shape. Then, the critical current density was measured under liquid nitrogen. Both before and after bending, a critical current density of 12,000 to 13,500 A/cm2 was obtained under liquid nitrogen.

Claims (1)

[Claims] 1. A multicore superconducting wire in which a plurality of superconductor parts made of an oxide superconducting material are arranged in a stabilizing material, in which a raw material for the superconducting parts is filled into a metal sheath serving as the stabilizing material to form a wire. A multicore superconducting wire, which is a superconducting wire obtained by bundling an assembly of wire rods into a wire rod in a metal sheath, and wherein the thickness of each of the superconductor parts is 10% or less of the thickness of the entire wire rod.