JPH0494014A - Ceramic superconductive conductor - Google Patents

Abstract

PURPOSE:To provide a ceramic superconductive conductor of an excellent mechanical strength and superconductive property by compounding a reinforcement layer consisting of a high strength of material selected from a group of a fiber-reinforced Ag alloy, a particle dispersed reinforced Ag alloy, and a heatproof high strength Ag alloy, to a ceramics superconductor layer through an interposition layer consisting of a precious metal or a precious metal alloy. CONSTITUTION:This ceramic superconductive conductor is a round wire-form substance made by compounding an interposition layer 2 around a ceramic superconductor layer 1 with a circular section, and furthermore, a reinforcement layer 3 on the peripheral surface, forming layers respectively. As the interposition layer 2, a ceramic surerconductor and a precious metal of inactive Ag, Au, Pt, and the like, or a precious metal alloy such as Ag-Ir, Ag-Pd, and Ag-Au are used. And as the reinforcement layer, a compound metal made by dispersing a particle form, a short fiber form, or a long fiber form of ceramics such as SiC, TiC, ZrC, ZrO2, Al2O3, and MgO in an Ag matrix is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ceramic superconductor having excellent mechanical and electrical properties and suitable for use in magnets, cables, FT style leads, etc.

(Prior art) In recent years, B 1-3r-Ca-Cu-0 system, Y −, B a
Ceramic superconductors such as Cu-0 series and Tl-Ba-Ca-Cu-0 series, whose critical temperature (Tc) exceeds the temperature of liquid nitrogen, have been discovered, and applied research in various fields is actively progressing. .

By the way, these ceramic superconductors are brittle, so in order to process them into linear objects, etc., a metal pipe is filled with a raw material that can be made into a ceramic superconductor (hereinafter abbreviated as raw material), and this is stretched. This is done using a method that

In addition, other manufacturing methods include kneading the raw material with a binder to form a paste, and applying this onto metal or layering it alternately with metal tape to form a composite. Furthermore, there is a method of stretching this.

In addition, extrusion, swaging, drawing, rolling, etc. are applied as the above-mentioned stretching method, and the stretched material can have a cross-sectional shape of circle, ellipse, polygon, tape, etc., or can be made into a multifilamentary wire or multilayer by bundling multiple pieces of these. A method of processing it into wires, etc., is being prototyped.

Then, the wire rod is finally heat-treated at high temperature in an oxygen-containing atmosphere to transform the raw material into a ceramic superlative! It is made into a ceramic superconductor by reacting with a conductor.

Incidentally, Ag is used as a composite metal material based on the raw material.

Ag alloy, Cu, Cu alloy, etc. are used, among which A
Since Ag alloy has excellent oxygen permeability, oxygen is sufficiently supplied to the internal raw materials, and the critical current density (Jc) of the resulting ceramic superelectric 44 body is improved, so it is preferable.

[Problem to be solved by the invention]

However, since such ceramic superconductor 44 bodies are manufactured by heat treatment at high temperatures as described above, the metal material such as Ag composited into the ceramic superconductor layer becomes extremely soft, and as a result, the ceramic superconductor layer When a small amount of tension is applied during coiling or the like, cracks occur in the internal ceramic superconductor layer, resulting in a significant deterioration in the superconducting properties of the wire.

For this reason, it has been proposed to use heat-resistant high-strength metal materials such as Fe, SUS, and Ni or composite materials such as fiber-reinforced metals as the metal material to be composited with the ceramic superconductor layer. The material or composite material reacts with the ceramic superconductor layer during the heat treatment to alter the quality of the superconductor layer, and as a result, the superconducting properties such as Jc of the superconductor decrease to about 20,000 to 30,000 A/cd. Another problem arose:

[Means to solve problems]

The present invention was made as a result of intensive research in view of the above situation, and its purpose is to provide a ceramic superconductor 44 having excellent mechanical strength and superconducting properties.

That is, in the ceramic superconductor 44 of the present invention, an intervening layer made of a noble metal or a noble metal alloy is composited around a ceramic superconductor layer, and a fiber-reinforced Ag or Ag
Alloy, particle dispersion strengthened Ag or Ag alloy, heat resistant high strength A
It is characterized by a composite reinforcing layer made of any high-strength material selected from the group of g-alloys.

The ceramic superelectric 44 body of the present invention will be specifically explained below with reference to the drawings.

FIG. 1 shows circular cross-sections of 44 embodiments of the ceramic superelectric body of the present invention. In the figure, l is a ceramic superconductor layer, 2 is an intervening layer, and 3 is a reinforcing layer.

The ceramic superconductor 44 body shown in FIG. In addition, the 44 ceramic superelectric bodies shown in the lower part are
The structure is the same as that shown in Figure A, except that the external shape is tape-like. Furthermore, Fig. C shows a structure in which a plurality of ceramic superconductor layers 1 are embedded in an intervening layer 2 in a mutually independent state, and a reinforcing layer 3 is further provided concentrically around the outer periphery of the intervening layer 2. . Further, in Fig. 2, a plurality of pipe-shaped ceramic superconductors 1.1' with different diameters are concentrically composited with intervening layers 2, 2' interposed therebetween, and a reinforcing layer 3 is further provided on the outermost periphery. 44 ceramic superelectric bodies are shown.

In the present invention, in addition to the various types of ceramic superconductors mentioned above being widely applied as raw materials, intermediates used until synthesis into the ceramic superconductor, which is a precursor of the ceramic superconductor, such as ceramics, etc. Mixtures of superconductor constituent elements, coprecipitated mixtures, oxygen-deficient composite oxides, alloys of the above constituent elements, etc. can be used, and these precursors react to the ceramic superconductor by heat treatment in an oxygen-containing atmosphere. It is something.

In the present invention, the intervening layer includes noble metals such as Ag, Au, and Pt that are non-reactive with the ceramic superconductor, or Ag-1r,
Noble metal alloys such as Ag-Pd and Ag-Au are applied.

Also, the reinforcing layer is Ag-Ni.

Heat resistant high strength Ag alloy such as Ag-Mo, SiC, TiC, ZrC, ZrO in Ag matrix.

A1. A composite material in which particulate, short fiber, or long fiber ceramics such as Os, MgO, etc. are dispersed is applied. This composite material can be produced using a molten metal forging method in which molten Ag is injected into a reinforcing fiber preform and pressurized, or a melt stirring solidification method in which particulate or fibrous ceramics are dispersed and solidified in molten Ag, or Ag-Affi alloy powder and Ag The mixed powder with powder is compression molded into a predetermined shape, and this compression molded body is heat-treated in an oxygen-containing atmosphere to internally oxidize Al to form Ag.
It is produced by any method such as a powder metallurgy method using an Al z Os-based particle dispersion strengthened alloy.

The method for manufacturing the ceramic conductor of the present invention will be specifically described below.

First, a composite material such as a fiber-reinforced Ag alloy is produced as described above, and this is made into a pipe shape by machining such as boring, and then a cylindrical body made of precious metal is fitted into the pipe to form a composite material. A composite billet is produced by filling the composite pipe with a raw material, and after hot extrusion, the composite billet is processed into a wire rod of a predetermined shape by ordinary stretching methods such as swaging, rolling, and drawing. Furthermore, this wire is heat-treated at a high temperature of 800 to 900°C in an oxygen-containing atmosphere to react and sinter the raw material into a ceramic superconductor, supply oxygen to the sintered body, adjust the crystal structure, etc. Thus, 44 ceramic superelectric bodies were manufactured.

The 44 ceramic superelectric bodies obtained as described above are collected by converging multiple wires in the case of round or square wires, or by winding them into a spiral shape in the case of tape or sheet shapes. It is also possible to cover the outer periphery of the body or spiral body with a high-strength material such as a noble metal material or a fiber-reinforced Ag alloy, and further perform stretching or heat treatment if necessary to form a ceramic superelectric body.

In addition to the above, the raw material is made into a green sheet using the doctor blade method, this is overlapped with a precious metal sheet and rolled up so that the precious metal sheet is on the outside, and this spiral body is placed inside a pipe made of high strength material such as fiber-reinforced Ag alloy. It is also possible to manufacture a composite billet by filling the billet into a composite billet.

[Effect]

The ceramic superconductor 44 of the present invention has a ceramic superconductor layer with an intervening layer made of a noble metal or a noble metal alloy. Since the reinforcing layer made of such high-strength material is composite, it will not become soft even when heated at high temperatures, and therefore the internal ceramic superconductor layer will not be cranked by the tension applied when coiling the wire. There's no way I'll go in.

Furthermore, since an intervening layer made of a noble metal or noble metal alloy that is non-reactive with the ceramic superconductor is provided between the reinforcing layer made of the high-strength material and the ceramic superconductor layer, the reinforcing layer made of the high-strength material and the ceramic superconductor There is no possibility that the ceramic or carbon superconductor layer will change in quality due to contact with the body layer and reaction.

〔Example) The present invention will be explained in detail below using examples.

Example 1 A120. A preform made of short fibers was set in a container with an inner diameter of 251 mm, and molten Ag heated to 1100°C was poured into the container and solidified under pressure to form a fiber-reinforced Ag ingot. Machined to outer diameter 2
A hollow billet with a diameter of 5w and an inner diameter of 16 m1+ was made, and an Ag pipe with an outer diameter of 15.81 mm and an inner diameter of 12 mm was fitted into this hollow billet to form a composite pipe, and then pre-sintered powder of Bi-based ceramic superconductor was placed inside this composite pipe. A composite billet was prepared by filling the billet with After that, this composite billet was sequentially subjected to swaging processing and rolling processing to obtain 5×0,
A 2 mm tape-shaped composite wire was prepared, and then this tape-shaped composite wire was subjected to heat treatment at 850'CX50Hr in the atmosphere to produce 44 ceramic superelectric bodies.

In addition, the pre-sintered powder of Bi-based ceramic superconductor is B 1z
03.5rCOs, CaC0:+, Cu0(7) powder with Bi:Sr:Ca:Cu atomic ratio of 2=21
: After mixing the mixture to give a ratio of 80% in the air,
The material was prepared by heating at 0° C. for 20 hours, pulverizing and classifying it.

Example 2 In Example 1, Ag was used as the material for forming the reinforcing layer and the intervening layer.
44 ceramic superelectric bodies were manufactured in the same manner as in Example 1, except that an Ag-Pd alloy was used instead.

Example 3 Ceramic superelectric 44 was produced in the same manner as in Example 1, except that a composite billet made in the same manner as in Example 1 was swaged and then drawn into a composite wire of 1.2 s-φ.
manufactured a body.

Example 4 Seven 1.21φ composite wire rods prepared in Example 3 were bundled into 7 frozen bundles, and this bundle was made into a bundle with an outer diameter of 61mm. A ceramic 2x superconducting conductor was heated in the same manner as in Example 1, except that it was filled into an Ag pipe with an inner diameter of 4 ms, and then drawn into a wire rod with an outer diameter of 2 mm. manufactured a body.

Example 5 Seven holes of 2 mIIφ were bored at equal intervals in a Pt billet with an outer diameter of 12 mm, and the pre-sintered powder of the Bi-based ceramic superconductor produced in Example 1 was filled into the holes to form a composite. This composite was then treated with the same fiber reinforcement A as used in Example 1.
The composite billet was inserted into a hollow billet made of aluminum with an outer diameter of 18 mm and an inner diameter of 12.5 mm, and this was drawn into a composite wire rod of 1.5 ms + φ. Thereafter, this composite wire was heat treated in the same manner as in Example 1 to produce a ceramic superconductor.

Example 6 Example! The pre-sintered powder of the Bi-based ceramic superconductor produced in the above was kneaded with a binder to form a paste, which was then formed into a green sheet with a thickness of 0.51 by the doctor blade method. Then, the obtained green sheet was
A mm-thick Au sheet is overlapped with the 51φ Ag round rod and wound in a spiral shape with the Au sheet facing outward, and then this spiral body is wrapped with the same fiber-reinforced A as used in Example 1.
A composite billet was prepared by filling a hollow billet manufactured by G. G with an outer diameter of 20 mm and an inner diameter of 15 mm. Next, this was sequentially subjected to swaging processing and drawing processing to obtain a composite wire of 2 mm diameter, and then subjected to heat treatment in the same manner as in Example 1 to produce a ceramic superconductor.

Comparative Examples 1 to 2 In Examples 1 and 3, the pre-sintered powder of Bi-based ceramic superconductor was directly filled into the fiber-reinforced Ag hollow billet without intervening an Ag pipe. Ceramic superconductors were manufactured by the same method as in Example 1 and Example 3.

Comparative Example 3 Same method as in Example 5 except that in Example 5, a composite formed by filling the calcined powder was inserted into a hollow Ag billet with an outer diameter of 1 B+am and an inner diameter of 12.5 mm to form a composite billet. A ceramic superconductor was manufactured using the following method.

Comparative Example 4 In Example 6, the green sheet and Au sheet were
The spiral body wound around the round body has an outer diameter of 2゜1 and an inner diameter of 15+.
A ceramic superconductor was produced by the same method as in Example 6, except that a composite billet was produced by filling a +s Ag hollow billet.

Each ceramic superconductor obtained in this way was formed into a coil with a diameter of 100+uW, and liquid nitrogen (7
7K), Jc was measured in the absence of a magnetic field. The results are shown in Table 1 along with the main manufacturing conditions.

As is clear from Table 1, the products of the present invention (Nal~6) all had higher Jc values than the comparative products (+!17~10).

In particular, when Ag is used in the metal matrix of the intervening layer and the reinforcing layer and rolled into a rectangular shape (failure 1), oxygen is sufficiently supplied during heat treatment, and the ceramic superconductor layer becomes dense, resulting in a high Jc value. showed that. Also, the material with multi-core material and increased processing rate (N114) also showed a high Jc. In addition, when PT or Au is used in the intervening layer (N[15,6), the oxygen supply during heat treatment is insufficient, resulting in a slight decrease in Jc, and in particular, Nα6 has a low Jc due to the residual binder. became.

On the other hand, the comparative products Nl117 and NcL8 did not have an intervening layer between the ceramic superconductor layer and the reinforcing layer, so
The ceramic superconductor layer is Al in the reinforcing layer.

It reacts with Nl119 and NCLIO.
Because no reinforcing layer was provided, cracks occurred in the ceramic superconductor layer due to the tension during coiling, resulting in extremely low Jc values in both cases.

〔effect〕

As described above, the ceramic superconductor of the present invention has excellent mechanical strength and superconducting properties such as Jc, and has remarkable industrial effects.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of the ceramic superconductor of the present invention. 1.1'... Ceramic superconductor layer, 2.2'
...Intervening layer, 3...Reinforcement layer.

Claims (1)

[Claims] An intervening layer made of a noble metal or a noble metal alloy is composited around the ceramic superconductor layer, and further surrounded by fiber-reinforced Ag or Ag alloy, particle dispersion-strengthened Ag or Ag alloy,
A ceramic superconductor comprising a composite reinforcing layer made of any high-strength material selected from the group of heat-resistant, high-strength Ag alloys.