JP3033606B2 - Manufacturing method of oxide superconducting wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an oxide superconducting wire.

[0002]

2. Description of the Related Art As a conventional method for manufacturing an oxide superconducting wire, as shown in FIG. 4A, a silver sheath 40 is filled with an oxide superconductor material 41 to form a silver sheath composite. A method of subjecting the silver sheath composite to surface reduction processing and performing a heat treatment on the raw material for oxide superconductor to form an oxide superconductor, as shown in FIG. 4 (b). A dispersion of silver members 42 in a linear body 4
3 and heat-treating the raw material for an oxide superconductor into an oxide superconductor, and FIG.
As shown in FIG. 7, a plurality of holes 45 having a predetermined size formed in a silver rod 44 are filled with an oxide superconductor raw material 41, and the rod 44 is subjected to surface reduction processing. There is a method of performing heat treatment for forming a body material into an oxide superconductor.

[0003]

Since the above-mentioned composite of silver and a raw material for an oxide superconductor has poor workability, the raw material portion for the oxide superconductor is separated in a step such as surface reduction. As a result, disconnection of the oxide superconducting wire is caused. Therefore, the critical current density of the oxide superconducting wire manufactured by such a method is lower than the critical current density of a superconducting wire made of a single crystal or a unidirectionally solidified material. This also reduces the current capacity of the oxide superconducting wire, that is, the current value.

[0004] Further, since the raw material for an oxide superconductor generates a gas when it becomes an oxide superconductor by a heating step such as sintering, so-called swelling of the wire occurs in the heat treatment step after the wire is formed. The outer diameter of the oxide superconducting wire fluctuates. Conventionally, in order to prevent this, a metal such as Ag having excellent oxygen permeability is dispersed in advance in the raw material for oxide superconductor, but simply dispersing such a metal in the raw material for oxide superconductor. Can not sufficiently prevent swelling of the wire in the heat treatment process after the wire is made,
In addition, the superconducting properties of the oxide superconducting wire are reduced.

The present invention has been made in view of the above circumstances, and has as its object to provide a method of manufacturing an oxide superconducting wire capable of easily obtaining an oxide superconducting wire exhibiting excellent superconducting characteristics. .

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a metal sheath
In the oxide subjected to a reduction process superconductor material into the metal sheath composite filled, a method of manufacturing an oxide superconducting wire subjected to a heat treatment for forming an oxide superconductor material in an oxide superconductor to the said metal A wire made of Ag or an Ag alloy is continuously arranged in the longitudinal direction inside the sheath composite , and the metal sheath composite obtained by reducing the surface of the metal is used as a metal.
Subject to the heat treatment while being covered with a metal sheath.
And a method for producing an oxide superconducting wire.

Here, as a raw material for the oxide superconductor to be used, any of Bi-based, Y-based, Tl-based and the like can be used. In addition, you may mix metal powders, such as Ag, with these oxide superconductor raw materials as needed.

As a method of continuously arranging a wire made of Ag or an Ag alloy inside a linear body made of a raw material for an oxide superconductor in the longitudinal direction, as shown in FIG.
The raw material 10 for oxide superconductor is formed into a linear body 1 by compression molding or the like.
1, a hole 12 having a desired size is formed therein, and a wire 13 made of Ag or an Ag alloy is inserted into the hole 12 ;
Next, a method of inserting the linear body 11 into a metal sheath (not shown), as shown in FIG. 1B, filling a metal sheath 14 with a raw material 15 for an oxide superconductor. A metal sheath composite 16 is formed, and thereafter, a hole 12 having a desired size is formed in a portion of the raw material 15 for an oxide superconductor.
Alternatively, a method of inserting the Ag alloy wire 13 or the like can be used. In this case, as shown in FIG. 1C, if at least one wire 13 is continuously arranged in the longitudinal direction at the portion of the oxide superconductor material 15, the other oxide superconductor material 15 may be used. Short Ag or Ag alloy 17 may be dispersed in the portion. As a material of the metal sheath, Ag or an Ag alloy having excellent oxygen permeability can be used.

As the surface reduction processing, conventional processing means such as extrusion, rolling, drawing, and swaging are used according to the shape of a linear body, a tape-like body, or the like. Therefore, the cross-sectional shape of the oxide superconducting wire can be made any shape such as a circle, an ellipse, a polygon, a rectangle, or a tape shape by the surface reduction processing. The heat treatment temperature for forming the oxide superconductor raw material into an oxide superconductor is selected according to the type of the oxide superconductor raw material.

The cross-sectional shape of the wire made of Ag or an Ag alloy is not particularly limited, and Ag shown in FIG. 2A and FIG.
Alternatively, the Ag alloy wire rod 22 may have a tape shape continuous in the longitudinal direction.

The distance between wires made of Ag or Ag alloy (ds in FIG. 3A) is preferably 5 to 500 μm. This is because if the distance between Ag or Ag alloy wires is less than 5 μm, the superconductor portion will be removed due to workability problems, and if the distance between wires exceeds 500 μm, the superconducting phase will not be oriented and Jc will decrease. is there.

[0012]

The method of manufacturing an oxide superconducting wire according to the present invention is characterized in that a wire made of Ag or an Ag alloy is continuously arranged in a longitudinal direction inside a linear body made of a raw material for an oxide superconductor. .

For this reason, the wire made of Ag or Ag alloy improves the workability of the entire oxide superconducting wire, thereby preventing the oxide superconducting wire from breaking during the surface-reduction processing, and obtaining the obtained wire. Demonstrates excellent superconducting properties. Furthermore, the wire made of Ag or Ag alloy contained therein suppresses swelling of the linear body during the heat treatment. Therefore, the target oxide superconducting wire can be manufactured without causing a change in the wire diameter.

Further, since the wire made of Ag or Ag alloy enhances the orientation of the oxide superconductor in the oxide superconducting wire, the superconducting properties of the obtained oxide superconducting wire in a high magnetic field can be prevented from deteriorating.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. Examples 1 to 6

First, a raw material powder for a Bi-based oxide superconductor having a composition ratio of Bi: Sr: Ca: Cu of 2: 2: 1: 2 and an Ag powder having a particle size of about 5 μm are respectively 9: 1. And mixed thoroughly. This mixed powder is made to have an outer diameter of 80.
mm, 6 columns of 100mm in length and filled and preformed,
These temporary compacts were subjected to a hydrostatic pressure compression treatment of 180 MPa to obtain six compacts.

Next, these molded articles have a diameter of 11.4.
Seven holes each having a length of 1 mm were formed so that the distance between them was 11.4 mm. A rod made of Ag having a diameter of 11.3 mm was inserted into each of the seven holes.
These molded articles were inserted into Ag pipes having an outer diameter of 100 mm and an inner diameter of 81 mm, respectively, and the ends were sealed. One of these
Six extruded billets were produced by applying a 50 MPa isostatic pressing treatment. Next, these extruded billets were subjected to isostatic pressing at room temperature to produce six linear bodies having an outer diameter of 25 mmφ.

Thereafter, each of these linear bodies was subjected to surface reduction processing in a swage to obtain six wires 30 having a cross section as shown in FIG. Subsequently, these wire rods are supplied to rolling mills having different grooves, and the opposite sides L shown in FIG. 3B are 3 mm (Example 1), 2 mm (Example 2), 1 mm (Example 3), 0. 5 mm (Example 4), 0.
Rectangular wires 32 of 2 mm (Example 5) and 0.1 mm (Example 6) were produced.

A 100 mm sample of each rectangular wire was sampled, and each sample was subjected to a heat treatment at 900 ° C. for 10 minutes, followed by a heat treatment at 840 ° C. for 50 hours. A superconducting wire was obtained. Examples 7 to 10

In the same manner as in Example 1, four molded articles were obtained. Next, a plurality of 10 mm × 2 mm continuous holes in the longitudinal direction were formed in these molded articles, and a 10 mm × 2 mm A was formed therein.
g Tape was inserted. Then, in the same manner as in Example 1,
Four wires having cross sections as shown in FIG. 2A were obtained. Subsequently, these wire rods were supplied to rolling mills having different grooves, and the opposite sides were each 1 mm (Example 7), 0.5 mm
mm (Example 8), 0.2 mm (Example 9), and 0.1
mm (Example 10) was prepared and subjected to the same heat treatment as in Example 1 to obtain oxide superconducting wires of Examples 7 to 10. Comparative Examples 1-3

The composition ratio of Bi: Sr: Ca: Cu is 2:
2: 1: 2 Bi-based oxide superconductor raw material powder;
Ag powder having a particle size of about 5 μm was mixed with 8: 2 and 6: 4, respectively.
(Ie, Ag powder addition rate is 20%, 40%)
Mixed powder obtained by mixing and thoroughly mixing (Comparative Example 1,
2) Only the raw material powder for Bi-based oxide superconductor (Comparative Example 3) was filled into three Ag pipes each having an outer diameter of 80 mm and a length of 100 mm to produce three extruded billets. Then, a rectangular wire having a width of 2 mm was prepared and subjected to the same heat treatment as in Example 1 to obtain oxide superconducting wires of Comparative Examples 1 to 3.

With respect to the oxide superconducting wires of Examples 1 to 10 and Comparative Examples 1 to 3, critical current density (Jc) and critical current (Ic) at 77 K, 0 T and 1 T, wire diameter before and after heat treatment, and oxide superconductivity The orientation ratio of the body was examined.
The results are shown in Table 1 below. Further, for the wires of Examples 1 to 10, the distance between Ag wires was also examined, and the results are also shown in Table 1 below.

[0023]

[Table 1]

As is evident from Table 1, the oxide superconducting wires (Examples 1 to 10) obtained by the method of the present invention exhibit excellent superconducting properties, and the fluctuation of the wire diameter before and after the heat treatment. Did not. Further, when the opposite side exceeds 2 mm and when the opposite side is less than 0.1 mm, the critical current density decreases. As the orientation ratio of the oxide superconductor increases, the rate of decrease in critical current density in a high magnetic field decreases. Further, it was confirmed that there was no disconnection in any of the oxide superconducting wires.

On the other hand, the oxide superconducting wires obtained by the conventional method (Comparative Examples 1 to 3) have poor superconducting characteristics,
It was confirmed that the wire diameter fluctuated before and after the heat treatment, and that the oxide superconductor was broken inside the wire.

[0026]

As described above, the method for producing an oxide superconducting wire according to the present invention can easily obtain an oxide superconducting wire exhibiting excellent superconducting properties such as a high critical current density and a high current density in a high magnetic field. Can

[Brief description of the drawings]

FIGS. 1A to 1C are explanatory diagrams showing an embodiment of the method of the present invention.

FIGS. 2A and 2B are explanatory views showing another embodiment of the method of the present invention.

FIGS. 3A and 3B are diagrams for explaining a rectangular wire in the method of the present invention.

FIGS. 4A to 4C are views for explaining a conventional method for manufacturing an oxide superconducting wire.

[Explanation of symbols]

10, 15, 20: raw material for oxide superconductor, 11: linear body, 12: hole, 13, 22: wire, 14: metal sheath,
16: metal sheath composite, 17: Ag member, 30: wire, 32: rectangular wire.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01B 13/00 565 H01B 12/00-12/16

Claims (1)

(57) [Claims] An oxide superconductor in which a metal sheath composite in which a metal sheath is filled with an oxide superconductor raw material is subjected to a surface reduction process, and a heat treatment for forming the oxide superconductor raw material into an oxide superconductor is performed. In the method for manufacturing a wire rod, a wire rod made of Ag or an Ag alloy is continuously arranged in the longitudinal direction inside the metal sheath composite, and a metal sheath composite obtained by reducing the surface of the metal sheath composite is covered with a metal sheath. A method for producing an oxide superconducting wire, which is subjected to the heat treatment as it is.