JPS63318017A - Electroconductive wire - Google Patents

Abstract

PURPOSE:To provide a long wire having good superconductive characteristics by including a plurality of elements consisting of ceramic core covered with superconductive material of oxide type. CONSTITUTION:Thin and flexible ceramic whisker, ribbon, or wire 1 is covered with a superconductive material 2 of oxide type, and they are collected to provide an electroconductive wire 3 in the form of thick wire or band. As material to this electroconductive wire formed by covering the ceramics with superconductive material of oxide type is flexible, twining of them together does not impair the superconductive characteristics even though pressure is applied. Thereby, wire- or band-shaped electroconductive wire with good superconductive characteristics is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrically conductive wire using a superconducting material, and in particular, to a long wire of an oxide-based superconducting material exhibiting a high critical temperature, if possible. This invention relates to the structure of the tightening wire.

[Conventional technology]

Recently, (MxLal-X)2CLI04 (M=Ba.

Sr, Ca), YO, 4Bao, g CuOa −y
It has been revealed that oxide materials such as oxide materials exhibit high superconducting critical temperatures (TC) of 30 or more than 90. For these materials, see, e.g., Japanese, Journal of, Applied.

Physics 26 (1987) pp. 517-518 (Japan, J., Appl. Phys.
.

26 (1987) pp, L517-518).

[Problem that the invention seeks to solve]

Since the oxide material with high Tc is hard and brittle,
The problem is that it is difficult to process it into electrically conductive wire. Conventionally, to solve this problem, the inside of a metallic pipe made of copper or silver was filled with powdered oxide-based superconducting material, and the material was rolled or drawn to create a wire. Ta. However, stress and heat are applied to the oxide-based superconducting material during the rolling and processing processes, resulting in deterioration of the superconducting properties, and in severe cases, the superconducting properties may no longer be exhibited. Furthermore, the above-mentioned method has the problem that it is difficult to produce a long superconducting wire, and the processing cost for producing the wire becomes high.

An object of the present invention is to solve the above-mentioned problems and provide a long wire exhibiting good superconducting properties.

[Means for solving problems]

In order to achieve the above object, the present invention collects a plurality of small and flexible ceramic whiskers,
It is characterized in that it is made into a thick wire-like or band-like electrically conductive wire material by a method such as twisting.

The ceramic materials used here include alumina (Af1203), zirconia (zrOs+), 2-quartz (
Oxides such as SiO2), titania (Ti203), magnesia (MgO), and stearidite (MgO
・SiO□), spinel (MgO-AQ, 203), mullite (3'A Q 203・2S10□), cordierite (
Mixed oxides such as 2Mg0.2AQ 203.5SiO□) are suitable. In addition to those mentioned above, metal oxides that can withstand heating in an oxidizing atmosphere of 900° C. or higher are also suitable for the purpose of the present invention.

Furthermore, depending on the purpose, it is also possible to coat the surface of a wire made from a collection of oxide-based superconducting materials with a metal such as copper or aluminum.

As oxide-based superconducting materials, Y-Ba-Cu -0,
L a -S r -B a-〇, Gd-Ba-Cu-
A material consisting of a rare earth or alkaline earth metal such as 0, copper, and oxygen is possible, but the composition is not limited to the above composition as long as it is an oxide-based material.

Methods for coating a ceramic core wire with oxide-based superconducting materials include vapor phase growth and vapor deposition.

The constituent metal elements or constituent oxides of the oxide-based superconducting material can be coated by sputtering or the like. Alternatively, the ceramic core wire may be coated by preparing a solution containing the constituent elements and dipping the ceramic core wire in the solution. After coating, the coating material can be imparted with superconducting properties by subjecting it to appropriate oxidation treatment or heat treatment.

The ceramic core wire was used here because the superconducting properties of the oxide-based superconducting material do not deteriorate. If a core wire made of metal or the like is used, a reaction or the like occurs with the oxide-based superconducting material, destroying the superconducting properties. Further, as the ceramic core wire, a material having a coefficient of thermal expansion close to that of the oxide-based superconducting material deposited thereon is desirable. If the difference in coefficient of thermal expansion is large, stress and strain are likely to be applied to the oxide-based superconducting material, resulting in deterioration of superconducting properties.

A particularly desirable range of thermal expansion coefficient for the ceramic core wire is 5 to 20 x 10-67°C.

[Effect]

Therefore, even if pressure is applied by twisting a plurality of these together, the superconducting properties will not be impaired, and a wire-shaped or band-shaped electrically conductive wire with good superconducting properties can be obtained.

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 Alumina (80203) fiber, zirconia (ZrO□) fiber, silica alumina (S]-02 with a diameter of 2 to 6 μm
A Q 20 a) Fiber, asbestos (MgO/SiO2)
was used as the core wire of the ceramic material. These fibers were sequentially placed in a high-frequency sputtering device, and the raw material of the oxide-based superconducting material was deposited to a thickness of about 2 μm using the following procedure. A Y-B a -'Cu oxide with a diameter of 5 inches prepared by a sintering method was used as a sputtering target.

'Y-Ba-Cu oxide was coated on the ceramic core wire while introducing Ar+3wt%0□ gas at 5×10=Torr. During sputtering, care was taken to constantly vibrate and rotate the ceramic core to ensure that the Y--Ba--Cu oxide was deposited on the ceramic core at a uniform thickness. After taking out the ceramic core wire coated with Y--Ba--Cu oxide from the sputtering device, it was placed in an electric furnace to produce a square in an oxidizing atmosphere. In FIG. 1(a), 1 is a ceramic core wire;
2 is a Y-Ba-Cu oxide-based superconducting material,
Compositional analysis results 'Y o, 4B ao, e ClO2-y (0≦y
≦1.5). This material is twisted together as shown in Figure 1 (b
) was prepared. The diameter of the wire is approximately 1+n
It is m. It was confirmed that these wires are flexible and can be bent and processed in the same way as ordinary twisted copper wire. The superconducting critical temperature (Tc) and critical current density (JC) of these wires at 4.2K were measured, and the results shown in Table 1 were obtained.

Table 1 Example 2 Ceramic core material: whiskers or short fibers of alumina (An2o3)-zirconia (ZrO2) and quartz (S) with a thickness of 1 to 6 μm
0□), titania (T i , ○2.), magnesia (
MgO), stearadite (MgO・SjO□), spinel (MgO-, In, □03).

Mullite (3AQ203.2Sj02) and cordierite (2Mgo.2AQ203.5Sj○2) were used. Sequentially exposed to 'Y, Ba and Cu vapors in a vacuum evaporation apparatus, the surface of each ceramic core material is exposed to Y-Ba.
A metal film of -Cu of 1 μm was deposited. These materials were placed in an electric furnace and compression molded at 800 to 980°C in an oxidizing atmosphere into a strip with a width of 5 mm and a thickness of 0.5 mm using mold rollers, and then the surface was formed into a 0.2 mm thick copper plate. An electrically conductive wire having a cross-sectional structure shown in FIG. 2 was prepared. Tc of this wire, J at 4.2K. was measured, and the results shown in Table 2 were obtained. All of these electrically conductive wires were flexible and could be bent in the same way as conventionally used copper wires.

Table 2 It goes without saying that the thickness of the coating of the oxide-based superconducting material should be such that the material of the electrically conductive wire does not lose its flexibility.

〔Effect of the invention〕

As described above, according to the present invention, an electrically conductive wire with high flexibility can be provided using an excellent superconducting material having a high critical temperature of 8 degrees. This electrically conductive wire can be used with bending properties similar to conventionally used copper wire, etc., and is a concrete material that expands the applications of oxide-based superconducting materials that exhibit excellent superconducting properties. effective.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are schematic diagrams of an electrically conductive wire material and an electrically conductive wire obtained by twisting the materials in Example 1 of the present invention, respectively, and FIG. 2 is a schematic diagram of an electrically conductive wire material in Example 2 of the present invention. It is a sectional view of a wire. 1... Ceramic core wire, 2... Oxide-based superconducting material,
3... Electrically conductive wire, 4... Short fibrous oxide superconducting material, 5... Copper plate.

Claims (1)

[Claims] 1. An electrically conductive wire material comprising a plurality of ceramic core materials coated with an oxide-based superconducting material.