JPH11273469A - Superconductive precursor composite wire and manufacture of superconductive composite wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxide superconductive composite wire having a low AC loss at a low cost by providing a metal layer such as an Au layer around a filament made of a precursor material for a superconductor, and arranging Ag or its alloy on its outside. SOLUTION: This superconductive precursor composite wire is provided with a layer of at least one kind of metal selected from Au, Pt, Pd, hand Rh around a filament, and Ag or an Ag alloy is arranged on its outside. The metal such as Au forms a high-resistance alloy between it and Ag by a heat treatment. When the composite wire is heat-treated for generating a superconductive material, a high-resistance layer of an Ag-Au alloy is formed around the filament, and an AC loss can be reduced by this high-resistance layer. These metals are used in the pure metal state easily available when a composite billet is assembled, thus the raw material cost can be reduced, and the manufacturing process is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a superconducting precursor composite wire capable of obtaining an oxide superconducting composite wire having reduced AC loss, and to a method for producing an oxide superconducting composite wire.

[0002]

2. Description of the Related Art An oxide superconducting wire, for example, a Bi-based superconducting wire or a Y-based superconducting wire is made of Ag or a superconducting material in order to secure oxygen permeability, workability, and orientation of the superconducting material necessary for producing the superconducting material. In general, it is manufactured by a powder-in-tube method in which a raw material powder of a superconducting substance is sealed in a sheath made of an Ag alloy, the surface is reduced, and rolling is performed.

When a superconducting wire manufactured by such a method is used in alternating current, if the electric resistance of the matrix portion is small, the filaments are electromagnetically coupled to each other to form a closed circuit, thereby shielding the fluctuating magnetic field. Joule loss (a type of AC loss) occurs due to the flowing current. As a method of reducing this Joule loss, Ag which is a sheath material is used.
Alternatively, there is a method in which elements such as Au, Pd, and Pt are added to an Ag alloy to increase electric resistance and reduce AC loss.

There are mainly two reasons for using precious metals such as Au, Pd, and Pt. One is that these noble metals hardly react with Bi-based and Y-based superconducting materials and do not adversely affect the superconducting properties. Another reason is that the Ag-Au alloy and Ag-Pd alloy formed as a result of adding these noble metals are excellent in workability, and a normal powder-in-tube method can be applied.

[0005]

However, Ag-Au alloys and the like are expensive because of low demand, and if they are used for the whole matrix, the whole obtained wire becomes expensive.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a superconducting precursor composite wire capable of inexpensively producing an oxide superconducting composite wire with reduced AC loss. Aim.

Another object of the present invention is to provide a method for manufacturing an oxide superconducting composite wire which enables low-cost production of an oxide superconducting composite wire with reduced AC loss. In order to solve the above-mentioned problems, the present invention provides an Au layer around a filament made of a precursor that can be a superconductor,
At least one metal layer selected from the group consisting of a Pt layer, a Pd layer, an Ir layer, and a Rh layer is provided, and Ag is provided outside the metal layer.
Alternatively, the present invention provides a superconducting precursor composite wire in which an Ag alloy is disposed.

Further, the present invention provides an Ag or Ag alloy layer around a filament made of a precursor which can be a superconductor, and an Au layer, a Pt layer, a Pd layer, an Ir layer outside the layer.
A superconducting precursor composite wire comprising at least one metal layer selected from the group consisting of a layer and a Rh layer.

The metal layer may be formed by a pipe, but may be formed by winding a foil, or by vapor deposition, coating, dipping, or the like. Further, the present invention relates to a method for forming Ag or Ag around a filament made of a precursor which can be a superconductor.
A plurality of alloy layers provided with an alloy layer are assembled, and a group consisting of a metal body made of Au, a metal body made of Pt, a metal body made of Pd, a metal body made of Ir, and a metal body made of Rh is included in the group of the collected filaments. A superconducting precursor composite wire, wherein at least one metal body selected from the group consisting of:

The metal body is preferably located at the center, but may be distributed at a plurality of locations. Furthermore,
The present invention heat-treats the above-described superconducting precursor composite wire to convert the precursor into a superconductor and diffuse at least one metal selected from the group consisting of Au, Pt, Pd, Ir and Rh. Thus, a method for manufacturing a superconducting composite wire, wherein a high-resistance alloy layer is formed, is provided.

The superconducting precursor composite wire according to the present invention has the following three embodiments. (1) A structure in which at least one metal layer selected from the group consisting of Au, Pt, Pd, Ir, and Rh is provided around a filament, and Ag or an Ag alloy is arranged outside the layer.

(2) Ag or A around the filament
g alloy layer, Au, Pt, Pd, Ir outside
And at least one metal layer selected from the group consisting of Rh.

(3) Au, Pt, Pd, and the like are included in a plurality of filament groups provided with a layer of Ag or an Ag alloy around them.
A structure in which at least one metal body selected from the group consisting of Ir and Rh is arranged.

In the case of the above structures (1) and (2), the thickness of the metal layer is preferably 0.05 to 5%, more preferably 0.05 to 3% with respect to the equivalent filament diameter.
It is good.

When the thickness of the metal layer is within the above range, the thickness of the high-resistance layer obtained after the heat treatment is sufficient to cut off the electromagnetic coupling between the filaments, and the cost is suppressed. I can do it.

Here, the equivalent filament diameter is the diameter of the circle assuming that the filament is a perfect circle. Usually, since a filament has a complicated shape due to processing, an equivalent filament diameter is obtained by similar calculation in consideration of the degree of processing from the stage of preparation.

In the case of the above structure (3), the equivalent diameter of the metal body is preferably determined to be 1 to 20% by weight of the total matrix weight excluding the filament portion of the superconducting wire, and preferably 1 to 10%. % Is more preferred.

When the equivalent diameter of the metal body is within the above range, the high-resistance layer obtained after the heat treatment is sufficient to cut off the electromagnetic coupling between the filaments, and it is possible to suppress an increase in cost. .

Here, the equivalent diameter is the diameter of the circle assuming that the metal body is a perfect circle. The metal layer and the metal body may be made of a single kind of metal, or may be made of a laminate of a plurality of kinds of metals.

Au, Pt, Pd, I used in the present invention
Any metal selected from the group consisting of r and Rh is a metal that forms a high-resistance alloy with Ag by heat treatment. For example, Au itself has low resistance, but forms a high-resistance Au-Ag alloy by heat treatment.

The superconducting precursor composite wire of the present invention described above is subjected to a heat treatment for producing a superconducting substance. At this time, Au or Ag diffuses, and as a result, an Ag—Au alloy Is formed. AC loss can be reduced by the high resistance layer formed in this manner.

According to the present invention, a metal selected from the group consisting of Au, Pt, Pd, Ir and Rh for forming a high resistance layer is a pure metal which is easily available at the time of assembling the composite billet. Since it is used, the raw material cost can be reduced and the manufacturing process can be simplified as compared with the case where a precious metal is alloyed for the entire matrix. Also, compared to the case where the whole matrix is made of an Ag-Au alloy, the amount of Au or the like used can be reduced, and in this regard, inexpensive manufacturing is possible.

In the case of the above (2), when the superconducting precursor composite wire is further made of Ag or an Ag alloy burette to form a wire, the Ag or Ag alloy is formed on both the inner and outer surfaces of a metal layer such as Au. Au—Ag
Are formed at both interfaces. Therefore, it is possible to produce a superconducting composite wire having a large amount of a high-resistance alloy layer surrounding the superconducting filament, a small AC loss, and to quickly diffuse Au and the like.

Further, in the case of the above (3), a linear or rod-shaped metal body can be used, so that there is an advantage that manufacture is easy. Next, another invention of the present application relates to assembling a plurality of filaments made of a precursor that can be a superconductor and having a layer of Ag or an Ag alloy provided around a filament, and including Au, Pt,
A superconducting precursor composite wire characterized in that at least one metal body made of an alloy containing at least one selected from the group consisting of Pd, Ir and Rh is arranged.

As alloys, Au, Pt, Pd, Ir and Rh may be alloyed with each other, or alloys of them with Ag may be used. This superconducting precursor composite wire is also heat-treated to convert the precursor into a superconductor and to diffuse at least one selected from the group consisting of Au, Pt, Pd, Ir and Rh, to obtain a high-resistance By forming the alloy layer, a superconducting composite wire with low AC loss can be manufactured.

Also in the present invention, the whole matrix is A
Compared with the case of forming with an alloy such as g-Au, the usage amount of Au or the like can be reduced, and the cost can be reduced. However, it takes time to alloy Au, Pt, and the like. But,
It is easy to manufacture because a linear or rod-shaped metal body can be used.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments will be described below as embodiments of the present invention. Example _{1 Bi2223 (Bi 2 Sr 2 Ca} 2 Cu 3 O 10) of the oxide superconducting material powder consisting of, diameter 15 mm, length 500m
The superconducting core was wrapped in a 0.1 mm-thick Au sheath and pressed into a rod shape of m. This is 16m inside diameter
m, an outer diameter of 20 mm, and a length of 550 mm were inserted into a pure silver pipe, and the diameter was reduced to 2 mm to obtain a composite multifilamentary strand. Plural wires of this composite multifilamentary wire are
Fits into a pure silver pipe with an outer diameter of 20mm and a length of 550mm,
Furthermore, diameter reduction processing and rolling are performed, thickness 0.2 mm, width 3 mm
To obtain a cross-sectional structure shown in FIG.

In FIG. 1, an oxide superconducting raw material powder 1 is wrapped in an Au sheath 2 and further accommodated in a pure silver pipe 3 to form a composite multifilamentary wire 4. 4 are housed in a pure silver pipe 5 to form a superconducting precursor composite wire.

Thereafter, the superconducting precursor composite wire having the cross-sectional structure shown in FIG. 1 was subjected to a superconducting heat treatment at 825 ° C. to produce a superconducting wire having a critical current density of 20 kA / cm ² . At this time, the Au atoms in the Au sheath 2 are
Of Ag—Au having a thickness of 1 μm
An alloy layer was formed.

The AC loss of the superconducting wire thus obtained was 4.3 J / m ^{3 as} measured by a magnetization method with an externally applied magnetic field of 10 mT. Further, the raw material cost was able to be reduced by about 50% as compared with the case where the Ag-10% Au alloy pipe was used in place of the pure silver pipe, and was manufactured in Comparative Example 2 described later.

Example 2 An oxide superconducting raw material powder made of Bi2223 (Bi ₂ Sr ₂ Ca ₂ Cu ₃ O ₁₀ ) was used to prepare a powder having a diameter of 15 mm and a length of 500 m.
The superconducting core was obtained by pressing the powder into a rod shape of m. This was inserted into a pure silver pipe having an inner diameter of 16 mm, an outer diameter of 20 mm, and a length of 550 mm, and was reduced in diameter until the diameter became 2 mm to obtain a composite multifilamentary element wire. The outside of the composite multifilamentary wire is set at 0.
A plurality of 1 mm thick Au sheaths wound around
AgM with inner diameter 16mm, outer diameter 20mm, length 550mm
g Fitted to a pipe, reduced in diameter, and rolled to a thickness of 0.2
2 mm and a width of 3 mm to obtain a cross-sectional structure shown in FIG.

In FIG. 2, the oxide superconducting raw material powder 11
Is wrapped in a sterling silver pipe 13 and further an Au sheath 12
To form a composite multifilamentary element wire 14. A plurality of the composite multifilamentary elementary wires 14 are accommodated in a pure silver pipe 15 to constitute a superconducting precursor composite wire.

Thereafter, the superconducting precursor composite wire having the cross-sectional structure shown in FIG. 2 was subjected to a superconducting heat treatment at 825 ° C. to produce a superconducting wire having a critical current density of 20 kA / cm ² . At this time, Au atoms in the Au sheath 12 diffuse into Ag of the pure silver pipe 13 and into Ag of the pure silver pipe 15,
Ag-Au alloy layers each having a thickness of 1 μm were formed.

The AC loss of the superconducting wire thus obtained was measured by a magnetizing method at an externally applied magnetic field of 10 mT and found to be 4.3 J / m ³ . Example 3 Bi-2223-based oxide superconductor material powder consisting of _{(Bi 2 Sr 2 Ca 2 Cu} 3 O 10), diameter 15 mm, length 500m
The superconducting core was obtained by pressing the powder into a rod shape of m. This was inserted into a pure silver pipe having an inner diameter of 16 mm, an outer diameter of 20 mm, and a length of 550 mm, and was reduced in diameter until the diameter became 2 mm to obtain a composite multifilamentary element wire. A plurality of strands of this composite multifilamentary wire are
A pure silver pipe having an inner diameter of 16 mm, an outer diameter of 20 mm, and a length of 550 mm was fitted. At that time, a Pt wire having a diameter of 1 mm was arranged at the center, diameter reduction processing and rolling were performed, and the thickness was 0.2 mm and the width was 3 mm.
mm, and the cross-sectional structure shown in FIG. 3 was obtained.

In FIG. 3, the oxide superconducting raw material powder 21
Is wrapped in a pure silver pipe 23 to form a composite multifilamentary wire 24, and a plurality of the composite multifilamentary wires 24 are housed in a pure silver pipe 25 in a state where a Pt wire 26 is arranged at the center. Thus, a superconducting precursor composite wire is formed.

Thereafter, the superconducting precursor composite wire having the cross-sectional structure shown in FIG. 3 was subjected to a superconducting heat treatment at 825 ° C. to produce a superconducting wire having a critical current density of 20 kA / cm ² . At this time, Pt atoms of the Pt wire 22 around the composite multifilamentary wire 24 diffuse into Ag of the pure silver pipe 23 and have a thickness of 0.5 μm.
An Ag-Pt alloy layer having a thickness of m was formed.

The AC loss of the superconducting wire thus obtained was measured by a magnetizing method with an externally applied magnetic field of 10 mT and found to be 5.1 J / m ³ . Comparative Example 1 Bi2223 oxide superconducting raw material powder was φ15 mm × L5
A superconducting core was obtained by pressing a bar having a diameter of 00 mm.
This is converted to an inner diameter of 16 mm, an outer diameter of 20 mm, and a length of 550 mm.
And then reduced in diameter to φ2 mm to obtain a composite multifilamentary strand. This is 16mm inside diameter, 20m outside diameter
It was fitted into a pure silver pipe having a length of 550 mm and a diameter of 550 mm, reduced in diameter and rolled, and processed into a tape shape having a thickness of 0.2 mm and a width of 3 mm. Thereafter, a superconducting heat treatment was performed at 825 ° C. to produce a superconducting wire having a critical current density of 20 kA / cm ² .

The AC loss of this wire was measured by a magnetization method with an externally applied magnetic field of 10 mT, and was found to be 36 J / m ³ . Comparative Example 2 In Comparative Example 1, Ag-10% was used instead of the pure silver pipe.
An Au alloy pipe was used.

The AC loss of this wire was measured by a magnetizing method at an externally applied magnetic field of 10 mT and found to be 4.0 J / m ³ . Example 4 A superconducting wire similar to that of Example 3 was produced except that a Pt-Ag alloy wire was used instead of the Pt wire. The AC loss of the superconducting wire thus obtained was measured by a magnetizing method with an externally applied magnetic field of 10 mT, and a value lower than Comparative Examples 1 and 2 was obtained.

[0040]

As described in detail above, according to the superconducting precursor composite wire of the present invention, metals other than Ag, such as Au, diffuse into Ag during the heat treatment for producing a superconducting material. Since a high-resistance layer such as an Ag-Au alloy is formed around the filament, the AC loss can be reduced by the high-resistance layer.

According to the superconducting precursor composite wire and the method for producing a superconducting composite wire of the present invention, a metal selected from the group consisting of Au, Pt, Pd, Ir and Rh for forming a high-resistance layer comprises: Since the fitting is performed in a pure metal state that is easily available at the time of assembling the composite billet, the cost of raw materials can be reduced and the manufacturing process can be simplified as compared with the case of using a precious metal alloy. Furthermore, the amount of expensive noble metal such as Au can be reduced as compared with the case where the entire matrix is made of an alloy, and as a result, inexpensive production becomes possible.

Even in the case of using a metal body made of an alloy such as Au, compared with the case where the whole matrix is alloyed,
There is an advantage that it can be manufactured at low cost. Furthermore, in the case of using a metal body, a linear object that can be easily handled can be used, and there is an advantage that it is easy to manufacture.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a superconducting precursor composite wire according to Example 1.

FIG. 2 is a cross-sectional view showing a superconducting precursor composite wire according to Example 2.

FIG. 3 is a sectional view showing a superconducting precursor composite wire according to a third embodiment.

[Explanation of symbols]

 1,11,21 ... oxide superconducting raw material powder 2,12 ... Au sheath 3,5,13,15,23,25 ... pure silver pipe 4,14,24 ... element wire for composite multi-core wire 26 ... Pt wire

Claims (5)

[Claims] At least one metal layer selected from the group consisting of an Au layer, a Pt layer, a Pd layer, an Ir layer, and a Rh layer is provided around a filament made of a precursor that can become a superconductor, and outside the filament, A superconducting precursor composite wire, comprising Ag or an Ag alloy. 2. A layer made of an Ag or Ag alloy is provided around a filament made of a precursor that can become a superconductor, and an outer layer thereof is selected from the group consisting of an Au layer, a Pt layer, a Pd layer, an Ir layer, and a Rh layer. A superconducting precursor composite wire comprising at least one metal layer. 3. A plurality of filaments comprising a precursor made of a superconductor and having a layer of Ag or an Ag alloy provided around the filaments, and a metal body made of Au, made of Pt, A superconducting precursor composite wire comprising at least one metal member selected from the group consisting of a metal member, a Pd metal member, an Ir metal member, and a Rh metal member. 4. A plurality of filaments made of a precursor or a superconductor and having a layer of Ag or an Ag alloy provided around the filaments, and Au, Pt, Pd, Ir A superconducting precursor composite wire comprising at least one metal body made of an alloy containing at least one selected from the group consisting of Rh and Rh. 5. The superconducting precursor composite wire according to claim 1, wherein said precursor is converted into a superconductor and said Au, Pt, Pd,
A method for manufacturing a superconducting composite wire, comprising diffusing at least one selected from the group consisting of Ir and Rh to form a high-resistance alloy layer.