JPH05211013A - Oxide superconductor and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide excellent insulation performance even after heat treatment by covering an oxide superconductor with a lamination layer composed of a metal sheath and a specific metal oxide. CONSTITUTION:An oxide superconductor 4 is covered with a sheath 5 of Ag and the like to form a long tape. An insulating member 3 of thickness 100mum or more covers the tape, and is an oxide including one element among Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W. The insulating member 3 and a superconductive tape wire rod 2 are superposed on each other and wound to make a superconductive coil. At the time of heat treatment, reaction between a component element of the oxide superconductor 4 in the wire rod 2 and the insulating member 3 is not caused, and therefore an insulation characteristic of the insulating member 3 is not deteriorated. Since diffusion of the component element of the superconductor 4 is prevented by the insulating member 3, a high performance coil whose critical current density is particularly high can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide superconducting conductor used in superconducting applications such as superconducting magnets, superconducting power transmission, superconducting energy storage, superconducting elements and medical equipment.

[0002]

2. Description of the Related Art In recent years, oxide superconductors having a critical temperature (Tc) higher than the liquid nitrogen temperature (about 77K) have been used, for example, Y-Ba-Cu-O system and Bi-Sr-Ca-Cu-O system.
Oxide superconductors such as those based on Tl-Ba-Ca-Cu-O system have been discovered. In order to apply these oxide superconductors to various superconducting devices such as electric power transportation, superconducting magnets, and superconducting devices, various researches have been conducted for practical application such as wire rods or coiling of oxide superconductors. There is.

Conventionally, various methods have been proposed for converting such an oxide superconductor into a wire rod, and an example thereof will be described. A solid phase method in which the constituent element compounds of the oxide superconductor are mixed and fired. Alternatively, fine particles of an oxide superconductor precursor are prepared by a liquid-phase synthesis method that produces a mixture of constituent elements in a liquid phase, and the fine particles are filled in a metal sheath such as silver, and the expanded and contracted diameter A wire rod is formed by processing, and the obtained wire rod is heat-treated in an oxygen atmosphere to produce an oxide superconducting wire rod.

Further, in the case of producing a superconducting cable wire made by bundling a plurality of superconducting wires, a superconducting tape laminated body in which a plurality of superconducting tape wires are laminated, or a superconducting coil obtained by winding the superconducting tape wires in a coil shape. Is
A plurality of wires or tapes before heat treatment are aggregated via an insulating material or wound into a coil and heat treated. As a method of coating the insulating material on the superconducting conductor, a method of winding a silica tape around the conductor surface or a method of coating ceramics such as alumina on the conductor surface can be used.

[0005]

However, when heat treating a wire or the like in which an oxide superconductor or its precursor is coated with a metal sheath, a phenomenon occurs in which constituent elements of the oxide superconductor diffuse through the metal sheath. When the silica tape is wound around the surface of the superconducting conductor for insulation, there is a problem that the diffused oxide or the like melts into the silica tape and reacts with the silica tape to deteriorate the insulation performance of the silica tape. Also,
Since the constituent elements diffuse to the outside, there is also a problem that the composition of the oxide superconductor partially changes and the superconducting characteristics deteriorate. In addition, when the surface of the superconducting conductor is coated with alumina or the like to be an insulating material, the coating layer is fragile, so that there is a problem that it peels off when bending is performed.

The present invention has been made in view of the above circumstances, and an oxide provided with an insulating material which does not react with an element diffusing from an oxide superconductor through a metal sheath and can obtain excellent insulating performance even after heat treatment. The purpose is to provide superconducting conductors.

[0007]

According to a first aspect of the present invention, as a means for solving the above problems, an oxide superconducting conductor obtained by coating an oxide superconductor with a metal sheath and coating the metal sheath with an insulating material. Where the insulating material is T
Provided is an oxide superconducting conductor comprising a metal oxide containing at least one metal element selected from i, Zr, Hf, V, Nb, Ta, Cr, Mo and W.

According to the second aspect of the present invention, there is provided an oxide superconducting conductor comprising a plurality of superconducting wire rods, each of which is formed by coating an oxide superconducting body with a metal sheath, by interposing an insulating material or winding the superconducting wire into a coil. , Ti, Zr, Hf, V,
An oxide superconducting conductor comprising a metal oxide containing at least one metal element selected from Nb, Ta, Cr, Mo and W.

The present invention also provides, as a method for producing the oxide superconducting conductor, a wire formed by coating the oxide superconductor or its precursor with a metal sheath, Ti, Zr, Hf, V, Nb, T.
at least 1 selected from a, Cr, Mo, W
It is possible to form an insulating material by assembling or winding in a coil shape through a metal material containing a certain kind of metal element, and heat-treating these aggregates or coils in an oxygen-containing atmosphere to oxidize the metal material. A method for producing a characteristic oxide superconducting conductor is provided.

[0010]

[Function] Ti, Zr, Hf, V, Nb, Ta, Cr, M
The metal oxides of o and W have excellent insulation performance and chemical stability. Since the oxide superconducting conductor according to the present invention uses these metal oxides as an insulating material, it does not react with the constituent elements of the oxide superconducting material that diffuse through the metal sheath during heat treatment, and has good insulating characteristics. To maintain. Further, the diffusion of the constituent elements of the oxide superconductor is prevented by the insulating material, and the diffusion of the constituent elements is suppressed.

Further, by applying this insulating material to an oxide superconducting conductor formed by assembling a plurality of superconducting wire rods or winding them in a coil shape through the insulating material, the oxide superconducting structure is formed through a metal sheath during heat treatment. The diffusion of elements is blocked by the insulating material, and good insulation is maintained between each superconducting wire.

Further, in the method for producing an oxide superconductor according to the present invention, the wire material obtained by coating the oxide superconductor or its precursor with a metal sheath is Ti, Zr, Hf, V, Nb, Ta, C.
r, Mo, W are aggregated or wound into a coil via a metal material containing at least one metal element selected from the group consisting of r, Mo and W, and these aggregates or coils are heat treated in an oxygen-containing atmosphere, and Since the insulating material is formed by oxidizing the metal material, it is possible to interpose the metal material between the wire materials by a simple method such as bonding tape-shaped metal materials.

[0013]

EXAMPLE FIG. 1 shows a superconducting coil which is an example of an oxide superconducting conductor according to the present invention. This superconducting coil 1 is formed by winding a large number of superconducting tape wires 2 and an insulating material 3 in a superposed state.

This superconducting tape wire 2 is made of Y-Ba-C.
u-O system, Bi-Sr-Ca-Cu-O system, Tl-Ba
An oxide superconductor 4 such as -Ca-Cu-O system is covered with a metal sheath 5 made of Ag or Ag alloy having good conductivity to form a long tape. By using such a silver sheath, in a Bi-based oxide superconductor or the like, the effect that the orientation of the superconductor particles becomes good and high characteristics are obtained can be obtained.

The insulating material 3 is made of Ti, Zr, Hf, V,
It is made of a metal oxide containing at least one metal element selected from Nb, Ta, Cr, Mo and W. These Ti, Zr, Hf, V, Nb, Ta, Cr,
The metal oxides of Mo and W have excellent insulation performance and chemical stability. The insulating material 3 may have a thickness of 100 μm or more.

This superconducting coil 1 is formed by winding a large number of insulating materials 3 made of the above-mentioned metal oxide having excellent insulation performance and chemical stability in a state of being superposed on the superconducting tape wire material 2, and thus is made into a coil. When heat treatment is performed later, the constituent elements of the oxide superconductor that diffuse from the oxide superconductor 4 in the superconducting tape wire 2 through the metal sheath 5 do not react with the insulating material 3, and the insulating property of the insulating material 3 does not occur. Does not deteriorate, resulting in good insulation. In addition, the insulating material 3 prevents diffusion of the constituent elements from the oxide superconductor 4,
Since the diffusion of the constituent elements can be suppressed, the coil has high superconducting characteristics, particularly high characteristics with a high critical current density (Jc).

Next, a method of manufacturing the superconducting coil 1 will be described with reference to FIGS. In order to manufacture this superconducting coil 1, first, the tape wire 6 shown in FIG.
And Ti, Zr, Hf, V, Nb, Ta, Cr, Mo,
A metal tape material 7 made of one type of W is prepared. The metal tape material 7 serves as a material for forming the insulating material 3 by being oxidized, and each of the above metals is preferably used, and a tape material made of an alloy of these metals or an alloy containing another metal is also used. It can also be used.

As an example of the method for producing the tape wire 6 shown in FIG. 3, the Y-Ba-Cu-O system and the Bi-Sr-Ca-Cu-O system obtained by the solid phase method, the chemical liquid phase synthesis method or the like are used.
, A Tl-Ba-Ca-Cu-O-based oxide superconductor, a precursor material 8 composed of a precursor powder thereof or a sintered body of the powder, is filled in an Ag tube, which is subjected to roll processing and rotary swaging. The tape wire 6 having the starting material 8 covered with the Ag sheath 9 is manufactured by performing a drawing process such as a zing process and a process of drawing and reducing the diameter into a tape having a desired size.

Next, the tape wire material 6 and the metal tape material 7 are overlapped with each other and further wound around the surface of the cylindrical body 10 many times to form a coil. Next, the formed coil is heat-treated in an oxygen atmosphere to cause a solid-phase reaction between the elements in the starting material 8 to generate the oxide superconductor 4, and
The metal tape material 7 is oxidized to generate the insulating material 3 made of a dense oxide. The temperature and time of this heat treatment and the conditions of the annealing treatment are appropriately set according to the type of oxide superconductor to be used. For example, in the case of manufacturing a Y—Ba—Cu—O based superconductor, 800 to 950 is used. 1 ~ at about ℃
After firing for several tens of hours, it is preferable to anneal at 500 ° C to 600 ° C.

By this heat treatment, the oxide superconductor 4 is generated, and the insulating material 3 made of a dense oxide is formed between the superconducting tape wire rods 2 to produce the superconducting coil 1 shown in FIG. During this heat treatment, the metal tape material 7 is rapidly oxidized to form the insulating material 3, so that the constituent elements (oxides) diffused from the starting material 8 or the oxide superconductor 4 through the metal sheath 5 during the heat treatment. In that case, the diffusion is almost completely blocked by the insulating material 3.

Therefore, according to the method of manufacturing the superconducting coil 1, the structure of the oxide superconductor which diffuses from the oxide superconductor 4 in the superconducting tape wire 2 through the metal sheath 5 when heat-treated after coiling. Since the element and the insulating material 3 do not react with each other and the insulating characteristic of the insulating material 3 does not deteriorate, the superconducting coil 1 having good insulating property can be obtained.
Further, since the insulating material 3 can prevent the diffusion of the constituent elements from the oxide superconductor 4 and suppress the diffusion of the constituent elements, the superconducting coil having high superconducting characteristics, particularly high critical current density (Jc), can be obtained. Is obtained.

In this manufacturing method, Ti, Zr, Hf, V, Nb, Ta and C are used as means for forming the insulating material 3.
Since the metal tape material 7 made of one of r, Mo, and W is laminated on the tape wire material 6 and wound in a coil, and the insulating material 3 is heat-treated and oxidized in an oxygen atmosphere to form the insulating material 3, it is easy to handle. Therefore, the insulating material 3 can be formed by a simple operation.

In the above embodiment, an example in which the present invention is applied to a superconducting coil has been shown, but the present invention is not limited to this embodiment. For example, a laminated material in which a plurality of superconducting tapes are laminated or a superconducting tape is used. It can be applied to various superconducting conductors such as a superconducting multi-wire in which a large number of wires are bundled or a superconducting film material.

(Experimental Example) Bi: Pb: Sr: Ca: Cu = 1.7: 0.3: 2: fine powders of bismuth oxide, lead oxide, strontium carbonate, calcium carbonate and copper oxide.
The mixture powder was mixed and pulverized to a 2: 3 (molar ratio) to obtain a mixed powder, and the obtained mixed powder was fired at 600 to 800 ° C. in the air to be pulverized, and further shaped into a rod to prepare a starting material. ..
This starting material was inserted into a cylindrical Ag sheath and stretched and reduced in diameter by a rotary swaging device to obtain a tape wire having a tape width of 4 mm and a tape thickness of 0.1 mm. On the other hand, prepare a Ta tape with the same width as this tape wire and a thickness of 0.1 mm.
Wrapped around. Next, this coil is placed in the atmosphere at 840 ° C. 2
It heat-processed for 00 hours and produced the superconducting coil. The obtained superconducting coil has a critical temperature (Tc) of 105 K or higher and a critical current density (Jc) of 2 × 10 ⁴ A / cm ² (77 K, 0).
T) and excellent performance.

Further, instead of the Ta tape, Ti, Z
A superconducting coil was similarly prepared using each of the metal tapes of r, Hf, V, Nb, Cr, Mo and W, and Jc of each superconducting coil was measured. As a result, Jc is all 1 × 10 ⁴ A /
It was not less than cm ² (77K, 0T).

On the other hand, for comparison, a silica tape is wrapped around the above tape wire, and this is wound around a columnar body to form a coil, which is then similarly heat treated to manufacture a superconducting coil.
As a result of measuring the Jc, Jc = 3 × 10 ² A / cm ² (7
It was about 7K, 0T).

[0027]

As described above, according to the present invention,
Ti, Zr, H with excellent insulation performance and chemical stability
By using an insulating material composed of metal oxides of f, V, Nb, Ta, Cr, Mo and W, it diffuses from the oxide superconductor through the metal sheath during heat treatment in the oxide superconducting conductor manufacturing process. Since the constituent elements of the oxide superconductor and the insulating material do not react with each other and the insulating characteristics of the insulating material do not deteriorate, the insulating property of the superconducting conductor is improved. Also,
Since the diffusion of the constituent elements from the oxide superconductor can be prevented by the insulating material and the diffusion of the constituent elements can be suppressed to the minimum, the superconducting characteristics of the oxide superconductor, particularly the critical current density (Jc), are improved. be able to. Further, as a means for forming this insulating material, Ti, Zr, Hf, V, Nb, T
After a metal material made of one of a, Cr, Mo, and W is added to a superconducting wire or the like, it is heat treated in an oxygen-containing atmosphere to oxidize the metal material to form an insulating material. It is easy and the insulating material can be formed by a simple operation.

[Brief description of drawings]

1A and 1B show a superconducting coil which is an embodiment of an oxide superconducting conductor according to the present invention, where FIG. 1A is a perspective view of the coil and FIG. 1B is an enlarged view of a coil cross section.

FIG. 2 is a perspective view for explaining a method of manufacturing the coil of FIG.

3 is a cross-sectional view of a tape wire used in the method for manufacturing the coil shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Superconducting coil, 2 ... Superconducting tape wire, 3 ... Insulator, 4 ... Oxide superconductor, 5 ... Metal sheath, 6 ... Tape wire, 7 ... Metal tape, 8 ... Starting material, 9 ... Ag sheath, 10 … Cylindrical body

Front page continuation (72) Inventor Nobuyuki Tekata 1-5-1, Kiba, Koto-ku, Tokyo Within Fujikura Electric Line Co., Ltd. Within the corporation

Claims (3)

[Claims] 1. An oxide superconducting conductor comprising an oxide superconductor covered with a metal sheath and the metal sheath covered with an insulating material, wherein the insulating material is Ti, Zr, Hf,
An oxide superconducting conductor comprising a metal oxide containing at least one metal element selected from V, Nb, Ta, Cr, Mo and W. 2. An oxide superconducting conductor comprising a plurality of superconducting wire rods comprising an oxide superconductor coated with a metal sheath, the insulating superconductor being assembled or wound in a coil shape, wherein the insulating material is Ti, Zr or Hf. , V, Nb, Ta, Cr, Mo,
An oxide superconducting conductor comprising a metal oxide containing at least one metal element selected from W. 3. A wire made by coating an oxide superconductor or its precursor with a metal sheath is used as Ti, Zr, Hf, V, Nb, T.
at least 1 selected from a, Cr, Mo, W
It is possible to form an insulating material by assembling or winding in a coil shape through a metal material containing a certain kind of metal element, and heat-treating these aggregates or coils in an oxygen-containing atmosphere to oxidize the metal material. A method for producing a characteristic oxide superconducting conductor.