JPH05211012A - Oxide superconducting conductor and method for manufacturing the same - Google Patents

Abstract

(57) [Summary] [Structure] An oxidation-resistant metal layer 13 made of an oxidation-resistant metal is provided on the oxide superconductor 12, and T is formed on the oxidation-resistant metal layer.
An intermediate oxide layer 14 containing an oxide of at least one metal element selected from i, Zr, Hf, V, Nb, Ta, Cr, Mo, and W is provided, and an external layer is provided on the intermediate oxide layer. An oxide superconducting conductor comprising a protective metal layer 15. [Effect] Even if the constituent elements of the oxide superconductor are diffused during the heat treatment, the diffusion is stopped by the intermediate oxide layer, so that the composition change of the oxide superconductor can be minimized and high Jc can be achieved.
The oxide superconducting conductor of is obtained. Further, since the intermediate oxide layer prevents the diffusion of the element from the oxide superconductor, the insulating material on the outer protective metal sheath is not contaminated by the diffusing element and the insulation performance is not deteriorated.

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 coated with a metal, which is used in superconducting application fields 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 toward the practical application of wire oxides or coils of oxide superconductors. ing.

FIG. 2 shows a superconducting tape wire which is an example of a conventionally known superconducting conductor obtained by coating an oxide superconductor with a metal. This superconducting tape wire 1 is Y
-Ba-Cu-O system, Bi-Sr-Ca-Cu-O system,
Tl-Ba-Ca-Cu-O-based oxide superconductor 2
Is covered with an external metal layer 3. When the superconducting tape wire 1 is used as a laminated wire or coil, an insulating material such as silica tape is provided on the outer metal layer 3. To make this superconducting tape wire 1,
Fine particles of oxide superconducting precursor prepared by powder method or liquid phase synthesis method were prepared, and these fine particles were filled in a metal sheath and subjected to expansion / contraction diameter processing such as roll processing or swaging processing. It is produced by heating a tape wire in an oxygen atmosphere.

[0004]

However, the superconducting conductor formed by coating the oxide superconductor 2 with the outer metal layer 3 like the above-mentioned superconducting tape wire 1 is subjected to heat treatment. , The element of the oxide superconductor 2 diffuses in the outer metal layer 3 and the composition of the oxide superconductor 2 is partially changed. There is a problem that the current density (Jc) becomes worse.

Since the constituent elements of the oxide superconductor diffuse through the outer metal layer 3, this outer metal layer 3
There is a problem in that the insulation of the superconducting conductor is difficult because it reacts with the insulating material provided on the upper side and the insulation performance of this insulating material deteriorates. The present invention has been made in view of the above circumstances, while preventing the deterioration of the superconducting characteristics by preventing the diffusion phenomenon of the oxide superconductor in the superconducting conductor, it is possible to prevent the deterioration of the insulating performance of the insulating material of the superconducting conductor. It is intended to be provided.

[0006]

In order to solve the above problems, the present invention provides an oxidation resistant metal layer made of an oxidation resistant metal on an oxide superconductor, and the Ti, Z
An intermediate oxide layer containing an oxide of at least one metal element selected from r, Hf, V, Nb, Ta, Cr, Mo and W is provided, and an external protective metal layer is provided on the intermediate oxide layer. An oxide superconducting conductor is provided.

Further, the present invention provides a method for producing an oxide superconducting conductor as described above, wherein an oxide resistant metal, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo,
An intermediate metal material containing at least one selected from W and an external protective metal are sequentially laminated and integrated to form an aggregate, and then the aggregate is heated in an oxygen-containing atmosphere,
There is provided a method for producing an oxide superconducting conductor, which comprises the step of oxidizing an intermediate metal material in the assembly with oxygen that has permeated an external protective metal, and forming an intermediate oxide layer in that portion.

[0008]

In the oxide superconductor of the present invention, an oxidation resistant metal layer made of an oxidation resistant metal is provided on the oxide superconductor, and Ti, Zr, Hf, V, Nb, Ta is formed on the oxidation resistant metal layer. , C
Since an intermediate oxide layer containing an oxide of at least one metal element selected from r, Mo and W is provided, and an external protective metal layer is provided on the intermediate oxide layer, it is possible that Even if the constituent elements of the oxide superconductor diffuse,
The diffusion is stopped at the intermediate oxide layer.

[0009]

EXAMPLE FIG. 1 shows an example of an oxide superconductor according to the present invention. In this example, the present invention is applied to a superconducting tape wire. The superconducting tape wire 11 shown in FIG.
An oxidation resistant metal layer 13 made of g is provided, and Ti, Zr, Hf, V, Nb, Ta, Cr, and
An intermediate oxide layer 14 containing an oxide of at least one metal element selected from Mo and W is provided, and an outer protective metal sheath 15 is provided on the intermediate oxide layer 14.

As the above oxide superconductor 12, YB
a-Cu-O system, Bi-Sr-Ca-Cu-O system, Tl
An oxide superconductor such as -Ba-Ca-Cu-O system is used. Further, as the external protective metal sheath 15,
A metal material having high mechanical strength and good workability such as stainless steel or copper alloy is preferably used.

The oxidation-resistant metal layer 13 is provided in direct contact with the oxide superconductor 12 as a sheath material for filling the powder or sintered oxide superconductor. The oxidation-resistant metal layer 13 uses an Ag sheath that does not react with the oxide superconductor during heat treatment during the production of the tape wire 11 and has a high conductivity. Also, such Ag
By using a sheath, in a Bi-based oxide superconductor or the like, the orientation of the superconductor particles becomes good, and the effect of obtaining high characteristics can be obtained.

The intermediate oxide layer 14 also acts as a diffusion barrier that prevents constituent elements of the oxide superconductor from passing through the oxidation resistant metal layer 13 and diffusing to the outside. The material of the intermediate oxide layer 14 is Ti, Z, which is a metal that produces a dense oxide having a good insulating property by being oxidized.
of at least one metal selected from r, Hf, V, Nb, Ta, Cr, Mo, W (elements of IVB group, VB group, VIB group of the periodic table) or alloys containing them as a main component Oxides are used, of which Ta is particularly preferred. The thickness of the intermediate oxide layer 14 varies depending on the oxide material used, but is preferably 100 μm or more. The intermediate oxide layer 14 can be formed by providing a metal layer of Ta or the like on the oxidation resistant metal layer 13, integrating the metal layer, and oxidizing the metal layer.

The external protective metal sheath 15 is used to improve the strength of the superconducting tape wire rod 11 and to prevent the metal layer such as Ta (metal layer serving as an intermediate oxide) from being seized during the processing of the tape wire rod. It is used to prevent the failure of the. On this outer protective metal sheath 15,
An insulating layer made of insulating material such as silica tape is provided,
A plurality of superconducting tape wire materials 11 are laminated or wound in a coil shape to be used for a superconducting cable or a superconducting coil.

In this superconducting tape wire 11, an oxidation resistant metal layer 13 made of Ag is provided on an oxide superconductor 12, and Ti, Zr, Hf, V, N is deposited on the oxidation resistant metal layer 13.
A structure in which an intermediate oxide layer 14 containing an oxide of at least one metal element selected from b, Ta, Cr, Mo, and W is provided, and an outer protective metal layer 15 is provided on the intermediate oxide layer 14. Therefore, during the heat treatment in the production of the tape wire, the constituent element of the oxide superconductor 12 is the oxidation resistant metal layer 13
Even though the oxide superconductor 12 diffuses through the intermediate oxide layer 14, the diffusion is stopped at the intermediate oxide layer 14, so that the oxide superconductor 12 due to the diffusion
It is possible to minimize the composition change of
The wire of c is obtained.

Next, as an example of the method for producing an oxide superconductor according to the present invention, the production of the superconducting tape wire rod 11 shown in FIG. 1 will be described as an example. As a starting material for the oxide superconductor used in the present invention, a powder of a superconductor or a precursor thereof obtained by a powder method, a chemical liquid phase synthesis method, or the like, or a molded body obtained by molding and calcining the superconductor is used.

This starting material is used as the oxidation resistant metal layer 13 A
While filling the g tube, cover the Ag tube with a pipe made of a metal that becomes an intermediate oxide such as Ta or wrap a metal tape such as Ta to form an intermediate metal layer, and further make stainless steel on the intermediate oxide. A sheath is covered to form an aggregate. Then, this aggregate is roll processed,
A drawing process such as a rotary swaging process is carried out to draw a tape of a desired size and reduce its diameter to obtain a tape wire.

Next, the tape wire thus obtained is heat-treated in an oxygen-containing atmosphere to form the oxide superconductor 12.
At this time, a stainless steel sheath (external protective metal sheath 1
Oxygen permeates the intermediate metal layer through 5) and is oxidized to form an intermediate oxide layer 14 made of an oxide of the metal,
Even if the constituent elements of the oxide superconductor 12 are diffused by the intermediate oxide layer 14 during the heat treatment, the diffusion is stopped by the intermediate oxide layer 14 and the composition change of the oxide superconductor 12 is minimized. You can Further, since the intermediate oxide layer 14 blocks the diffusion of the element from the oxide superconductor 12, even if the insulating material such as silica tape is wound around the outer protective metal sheath 15, the insulating material will not be removed. The insulating performance is not deteriorated by being contaminated by the diffusing element.

(Experimental Example) Bi: Pb: Sr: Ca: Cu = 1.7: 0.3: 2: fine powder of bismuth oxide, lead oxide, strontium carbonate, calcium carbonate and copper oxide.
The mixture powder is mixed and pulverized to a 2: 3 (molar ratio) to obtain a mixed powder, and the obtained mixed powder is fired at 600 ° C. to 800 ° C. in the air to be pulverized, and further shaped into a rod to prepare a starting material. did. This starting material was inserted into a cylindrical Ag sheath having a thickness of 2.5 mm and an outer diameter of 10 mm, and the thickness of 10 mm was applied to the outer surface of the Ag sheath.
mm Ta pipe, and then put it into a stainless steel pipe with a thickness of 10 mm and an outer diameter of 50 mm, and draw and reduce the diameter with a rotary swaging device to obtain a tape width of 20 mm and a tape thickness of 0.5 mm. It was a tape wire. Wrap an insulating silica tape around this tape wire in the air,
Heat treatment was performed at 840 ° C for 200 hours to obtain a superconducting tape wire. When the obtained superconducting tape wire was examined, diffusion of constituent elements of the oxide superconductor was not found on the surfaces of the stainless steel and the Ag layer. No evidence of reaction was found on the silica tape wound around the surface. Further, as a result of measuring the critical current density (Jc) of this superconducting tape wire, Jc = 3 × 10 ⁴ A / cm ² (77K, 0T), which showed high characteristics.

Further, instead of the Ta tape, Ti, Z
Similarly, a superconducting tape wire rod was produced by using each tape member of r, Hf, V, Nb, Cr, Mo, and W. As a result, it was found that even when each of these metal tapes was used, an intermediate oxide layer similar to Ta was formed, and this intermediate oxide layer could prevent the diffusion of the constituent elements of the oxide superconductor. Also,
Regarding the Jc of these superconducting tape wires, Jc = 1 to
It was about 3 × 10 ⁴ A / cm ² .

On the other hand, for comparison, the Ag sheath is filled with the above-mentioned starting material and directly subjected to rotary swaging to produce a superconducting tape wire having the structure shown in FIG. 2, and a silica tape is wound around the surface of the superconducting tape wire. Was heat-treated to prepare a superconducting tape wire. In the obtained superconducting tape wire, the element diffused into the silica tape permeated and some alteration was observed. Moreover, as a result of measuring Jc, Jc = 1 × 10
^{It was 4} A / cm ² (77K, 0T).

[0021]

As described above, according to the present invention,
An oxidation resistant metal layer made of an oxidation resistant metal is provided on the oxide superconductor, and Ti, Zr, Hf, V,
An intermediate oxide layer containing an oxide of at least one metal element selected from Nb, Ta, Cr, Mo and W is provided, and an external protective metal layer is provided on the intermediate oxide layer. Therefore, even if the constituent elements of the oxide superconductor are diffused during the heat treatment, the diffusion is stopped in the intermediate oxide layer, so that the composition change of the oxide superconductor can be minimized and the superconducting characteristics are excellent. An oxide superconducting conductor is obtained. In addition, since the intermediate oxide layer prevents the diffusion of elements from the oxide superconductor, even if heat treatment is performed with an insulating material such as silica tape wrapped around the external protective metal sheath, the insulating material will diffuse. The insulation performance does not deteriorate due to elemental contamination.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a superconducting tape wire which is an example of an oxide superconductor according to the present invention.

FIG. 2 is a cross-sectional view showing a conventional superconducting tape.

[Explanation of symbols]

11 ... Superconducting tape wire (oxide superconducting conductor), 12 ...
Oxide superconductor, 13 ... Oxidation resistant metal layer, 14 ... Intermediate oxide layer, 15 ... External protective metal sheath.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Tadakata 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Electric Wire Co., Ltd.

Claims (2)

[Claims] 1. An oxidation resistant metal layer made of an oxidation resistant metal is provided on an oxide superconductor, and Ti, Z is formed on the oxidation resistant metal layer.
An intermediate oxide layer containing an oxide of at least one metal element selected from r, Hf, V, Nb, Ta, Cr, Mo and W is provided, and an external protective metal layer is provided on the intermediate oxide layer. An oxide superconducting conductor characterized by being provided. 2. A method for producing an oxide superconducting conductor in which an oxide superconducting material is coated with a metal material, wherein an oxidation resistant metal and Ti, Zr, Hf, V, N are provided on the oxide superconducting material.
b, Ta, Cr, Mo, W, an intermediate metal material containing at least one selected from the group and an external protective metal are sequentially laminated and integrated to form an aggregate, and then the aggregate is placed in an oxygen-containing atmosphere. By heating the intermediate metal material in the assembly,
A method for producing an oxide superconducting conductor, which comprises a step of oxidizing an external protective metal with oxygen that has permeated, and forming an intermediate oxide layer in that portion.