JPH01204313A - Manufacture of superconductive hollow cable made of oxide - Google Patents

Abstract

PURPOSE:To make it possible to obtain a superconductive hollow cable made of oxide capable of being stacked in layers without applying any bending strain to tape wire material and having a high current density and a lager current capacity by setting a superconductive tape wire material made of oxide and having a high critical density given preset curvature in the tape thickness-direction in a rolling processing stage, in the circumferential direction and the radial direction of an air core cable. CONSTITUTION:After oxide superconductive powder is filled in a metal pipe and a surface reducing process such as wire-drawing is carried out, a rolling process is applied to give a preset curvature in a tape thickness-direction. Then, plurality of superconductive tape wire material 1 made of oxide having a preset curvature obtained by heat treatment are set by soldering etc., to increase the appropriate area in the circumferential direction and the radial direction of a cable cross-section so that an air core cable 2 may be constructed. Or, normally conductive metal pipe 3 of an excellent heat conductivity is employed in the most inside layer of the air core cable, and on the base of this normally conductive metal pipe 3, superconductive tape wire material 1 may be set and stratified. Thus, a superconductive hollow cable 2 made of oxide and having a high current density and a large current capacity can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oxide superconducting hollow cable, and particularly to a method for manufacturing an internally cooled cable with high current density and large current capacity.

[Conventional technology]

The recently discovered oxide superconductor has a critical temperature Tc of approximately 90°C, and is attracting attention because its property of zero electrical resistivity can be utilized by using liquid nitrogen as a cooling medium. A method of lengthening an oxide superconductor to make a wire rod has been described in the Japanese Journal of Applied Physics Vol. 26, No. 5 (1987), pages L865 to L866.
f Applied Physics VoQ26. N
CL5 (1987) spp, L865-L86
As described in 6), a method is known in which a metal pipe is packed with oxide superconducting powder, the area is reduced to a desired size by wire drawing, etc., and then heat treated to obtain a wire-like wire. Alternatively, after drawing the wire in the above-mentioned process, it is formed into a tape shape by rolling and then heat-treated to obtain a tape wire, and other methods such as a coating method, a thermal spraying method, etc. are known to obtain a thick film-shaped wire.

BACKGROUND ART It is generally known that one method of using superconducting wires in power transmission cables is to form the center of the conductor into an air-core shape and use the hollow portion as a flow path for a cooling medium. By the way, since power transmission cables transport large currents, they must have a large cross-sectional area.

[Problem to be solved by the invention]

When making a hollow power transmission cable using oxide superconducting wire, thick-film wires produced by coating or thermal spraying methods are disadvantageous because they require many layers of layers, in that the cross-sectional area of the cable must be increased as mentioned above. be. Furthermore, power transmission cables have limitations such as diameter size and weight, and it is also necessary to increase the cable's transfer current density, which requires a wire material with a high critical current density. In terms of critical current density,
In the case of oxide superconducting wires, tape wires are superior to wires in terms of crystal orientation, oxygen diffusivity during heat treatment, etc. However, since oxide superconducting wire has extremely poor mechanical properties such as strain resistance, in order to obtain a hollow power transmission cable by laminating multiple oxide superconducting tape wires, it is necessary to wind them in a spiral shape around a hollow cylinder. Either they can be stacked together, or they can be stacked straight in the longitudinal direction of a hollow cylinder, but in either case, conventional tape wires suffer from bending strain, which can easily cause cracks inside the wire and impair superconducting properties. was there.

The above-mentioned conventional technology does not consider increasing the current capacity of the oxide superconducting wire, and there is a particular problem in making the oxide superconducting wire into a hollow cable.

An object of the present invention is to provide a method for manufacturing an oxide superconducting hollow cable with high current density and large current capacity.

[Means to solve the problem]

The above purpose was achieved by packing the oxide superconducting powder into a metal pipe and subjecting it to surface reduction processing such as wire drawing, then rolling it so that it had a predetermined curvature in the tape thickness direction, and then heat-treating it. Soldering of a plurality of oxide superconducting tape wires having a predetermined curvature in the circumferential direction and radial direction with respect to the cross section of the cable is achieved by joining them to form a large area so as to form an air-core cable.

Alternatively, a normal conducting metal pipe with excellent thermal conductivity may be used as the innermost layer of the air-core cable, and oxide superconducting tape wires may be bonded and laminated based on this normal conducting metal pipe.

Furthermore, a tape-shaped normal conducting metal having excellent thermal conductivity may be interposed between the oxide superconducting tape wires.

[Effect]

By joining oxide superconducting tape wire with high critical current density, which has been given a predetermined curvature in the thickness direction of the tape during the rolling process, in the circumferential direction and radial direction to the cross section of the air-core cable. , it is possible to laminate the tape wire without applying bending strain.

〔Example〕

Examples of the present invention will be described below.

First Embodiment Two embodiments are shown in FIG. Wall thickness 1mm
, a work-hardened copper pipe with an outer diameter of 201Tf11,
4.5m thick covered with 0.5mm thick silver sheath material
An oxide superconducting tape wire having an average radius of curvature of 12.25 mm at the center in the thickness direction is soldered to a copper pipe so as to divide the pipe into four parts, and then an average radius of curvature of 16 mm is soldered onto the copper pipe in the same manner. An oxide superconducting hollow cable was fabricated by soldering .25+@ oxide superconducting tape. According to this embodiment, liquid nitrogen is poured into the hollow part, and 17
A current of 000A could be transferred. This current value is 90% of the total critical current of the oxide superconducting tape wire used in this example.

Second Embodiment Two embodiments are shown in FIG. A copper pipe similar to that used in the first embodiment was provided with a plurality of holes each having a diameter of 6 m as shown in FIG. 3, and the first layer of oxide superconducting tape wire was soldered to the copper pipe. This first layer was configured to have grooves in four locations in the circumferential direction with respect to the cross section of the cable. The second layer of oxide superconducting tape wire was laminated on the first layer via a 0.1 mm thick copper tape.

After laminating up to the fourth layer in the same manner, the fifth layer was laminated so as to completely surround the cable so that there were no grooves. In addition, the copper tape between the fourth layer and the fifth layer,
The fifth layer of oxide superconducting tape wire was laminated with the layers up to the fourth layer shifted by 45° in the cable circumferential direction. According to this example, it was possible to increase the cooling efficiency for the outer layer, and by flowing liquid nitrogen into the hollow part, it was possible to transfer current up to 98% of the total critical current of each oxide superconducting tape wire.

〔Effect of the invention〕

According to the present invention, oxide superconducting tape wires with a high critical current density can be laminated without bending strain, that is, without causing a decrease in the critical current density. A superconducting hollow cable is obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an oxide superconducting hollow cable according to a first embodiment of the present invention, FIG. 2 is a perspective view of an oxide superconducting tape wire having a curvature in the thickness direction shown in FIG. 1, and FIG. The figure is a perspective view of the copper pipe used in the second embodiment of the present invention, Figure 4 is a cross-sectional view of the oxide superconducting hollow cable of the second embodiment, and Figure 5 is a conventional oxide superconducting tape wire. FIG. DESCRIPTION OF SYMBOLS 1... Oxide superconducting tape wire, 2... Oxide superconducting hollow cable, 3... Copper pipe, 4... Cooling channel, 5... Oxide superconductor, 6... Normal conductivity Metal sheath, 7...Normal conductive metal tape.

Claims (1)

[Claims] 1. An oxide superconducting hollow cable obtained by laminating oxide superconducting tapes made of a normal conducting metal and an oxide superconductor, characterized in that oxide superconducting tapes having a predetermined curvature in the tape thickness direction are laminated. Method for manufacturing oxide superconducting hollow cable.