JP2951423B2 - Manufacturing method of ceramic superconducting conductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cable, a magnet,
The present invention relates to a method for manufacturing a ceramic superconducting conductor that can be used for a current lead or the like.

[0002]

2. Description of the Related Art In recent years, Y-Ba-Cu-O, Bi-S
Ceramic superconductors of Tc exceeding liquid nitrogen temperature, such as r-Ca-Cu-O and Tl-Ba-Ca-Cu, are known. It has been studied to mold such ceramic superconducting conductors into various shapes for the purpose of application and application in various fields. For example, there is a method of molding into a linear body. In that case, conventionally, a metal sheathing method is generally used. This is a method in which a ceramic material to be a superconductor is filled in a metal pipe, which is reduced in diameter and processed to a desired shape and dimensions, and then subjected to a predetermined heat treatment to make the ceramic material a ceramic superconductor. is there. The linear body may have a round, elliptical, or polygonal cross section, or a multi-core shape formed by bundling a plurality of these, or a ceramic superconductor in a metal having a concentric cylindrical or spiral shape. Prototyping of a multi-layered one provided in a shape is being studied. As the method of the diameter reduction processing, extrusion, rolling, and swaging are performed according to the shape of the obtained linear body.
Conventional plastic working methods such as jing and drawing are applied as they are. As the metal, a material having excellent heat conductivity and electric conductivity, for example, Ag, Ag alloy, Cu, Cu alloy, etc. can be used. In many cases, Ag and Ag alloy are used in terms of oxygen permeability.

In recent years, it has been studied to use such a tape multi-core ceramic superconductor for a cable as shown in FIG. The cable shown in FIG. 5 has a plurality of tape multi-core ceramic superconductors B arranged around a metal rod or pipe A. In this case, a tape multi-core ceramic superconductor B having a high Jc is desired. However, in order to obtain a ceramic superconductor having a high Jc, the crystal orientation of the ceramic superconductor is required. It is necessary to make the thickness of the superconductor as thin as possible. Conventionally, a relatively high superconducting property has been obtained with a rolled tape-shaped conductor, but the Jc value is 10 ⁴ (A / cm).
² ) The extent was the limit. In order to improve the superconducting characteristics, the present applicant has previously filed a method for manufacturing a ceramic superconducting conductor as shown in FIG. 8 (Japanese Patent Application No. 64-1099). However, in the method of manufacturing a ceramic superconductor shown in FIG. 8, a rod-shaped composite D of a ceramic raw material and a metal to be a superconductor is applied from its thickness direction (vertical direction in the figure) as shown in FIGS. This is a method in which the pressure is applied by the pressing dies E and F, and the pressure is sequentially and continuously applied in the longitudinal direction of the rod-shaped composite D as shown in FIG.

[0004]

However, in the method of manufacturing a ceramic superconducting conductor shown in FIG. 8, the rod-shaped composite D is pressed in the direction of its thickness by pressing dies E and F. Since both side surfaces in the width direction of D are open, the pressurized rod-shaped composite D locally spreads in the width direction as shown in FIG. 7, and the shape of the obtained tape-shaped superconductor G is obtained. However, there is a problem that the tape width is difficult to be constant as shown in FIG. Tapes with uneven tape width
For example, the tape-shaped superconductor G may be used as a tape multi-core ceramic superconductor B of a cable H as shown in FIG. 5 or may be spirally wound as shown in FIG. If it is used, there is a problem that the winding becomes difficult and the shape is deteriorated, or the tape-shaped superconducting conductors G are overlapped with each other and the superconductivity is deteriorated by the stress.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a ceramic superconducting conductor having a shape which can be used for a cable as shown in FIG. 5 or a magnet as shown in FIG. To provide.

[0006]

The present invention has been developed as a result of repeated experiments in order to solve the above-mentioned problems. As shown in FIG. 1, the method for manufacturing a ceramic superconducting conductor of the present invention is to adjust the arbitrary length of a composite 3 of a ceramic raw material 1 and a metal 2 to become a superconductor in a thickness direction while restraining a lateral side of the composite. It is characterized by applying pressure, sequentially and continuously applying the pressure in the longitudinal direction of the composite 3, and then heat-treating the composite 3 to turn the ceramic raw material 1 into a superconductor.

In the method for manufacturing a ceramic superconductor according to the present invention, first, a ceramic raw material 1 to be a superconductor is prepared. As a method for obtaining the raw material 1, conventional means can be applied as it is. For example, it can be obtained by blending and mixing primary raw material powders such as oxides and carbonates containing the elements constituting the superconductor so as to have a desired composition, calcining, and further pulverizing. Alternatively, it can be obtained by heating and melting the above-mentioned raw material powder, quenching it, and pulverizing it.
The calcined powder (ceramic raw material to be a superconductor) 1 thus obtained is filled into a metal pipe to form a composite billet (composite) 3. In this case, the calcined powder may be filled as it is, or may be molded into a desired shape by powder compaction, CIP molding or the like and then inserted. It is possible. in this case,
The raw material 1 may be configured to have a multi-core shape or a multilayer shape. The size of the complex 3 can be determined as appropriate. For example, when the size of the composite 3 is large, the composite 3 is subjected to plastic working, finished to a predetermined size, and then molded using the pressing jig 5 so as to have a desired size.
Next, the composite body 3 produced as described above is subjected to plastic working. For example, as shown in FIG. 1, compression molding is performed using, for example, a pressing jig 5 of a press type. In this case, after molding the composite 3 for an arbitrary length, the composite 3 is sequentially and continuously pressure-molded in the length direction. The speed of the compression molding can be appropriately selected.

The pressurizing jig 5 has a pressurizing portion 6 formed by recessing a part thereof. The width a of the pressurizing section 6 is determined by the obtained table.
The width is almost the same as the width of the wire. Pressing part 6 of pressing jig 5
Is determined according to the thickness of the obtained tape-shaped wire. When pressure is applied by the pressing jig 5, both sides in the width direction of the composite 3 are restrained by both side surfaces 7 and 8 of the pressing portion 6 in the width direction, so that the composite 3 is pressed in its thickness direction. However, it does not protrude in the width direction of the composite 3. The illustrated embodiment is an example in which the shape of the obtained ceramic superconductor is a tape-shaped linear body, but the shape of the ceramic superconductor obtained by the method for manufacturing a ceramic superconductor of the present invention is not limited to this. Instead, for example, it may be a vertically long ellipse as shown in FIG. 2, a horizontally long ellipse as shown in FIG. 3, or a polygon as shown in FIG. In the present invention, the tape-shaped linear body obtained as described above is heat-treated, and the ceramic raw material 1 in the composite 3 is used as a superconducting conductor. In the above description, the compression processing and the heat treatment are performed only once. However, in the present invention, the compression processing and the heat treatment as shown in FIG. When the heat treatment is further performed after the formation, the superconducting properties are further improved.

[0009]

The tape-shaped ceramic superconductor obtained by the manufacturing method of the present invention has a uniform width. Therefore, as shown in FIG. 5, a metal round bar, a pipe or the like (metal core) is used. In this case, it is possible to form a cable or a magnet having an excellent shape and superconducting characteristics without causing the ceramic superconducting conductors to overlap with each other and without overlapping the ceramic superconducting conductors. Further, in the case of spirally winding as shown in FIG. 6, since the bending strain applied to the ceramic superconductor becomes small, the superconducting characteristics do not deteriorate.

[0010]

Embodiment 1 Bi ₂ O ₃ , SrCO ₃ , CaCO ₃ , C
After mixing and mixing the primary raw material powders such as uO in a molar ratio of 2212, the mixture is calcined at 820 ° C. for 20 hours in an oxygen stream, and further pulverized to obtain a calcined powder having an average particle size of about 5 μm (with ceramic superconductor). Raw material). This is CI
P molded into a round bar with an outer diameter of about 15 mmφ, and A which has been machined in advance and has an outer diameter of 25 mmφ and an inner diameter of 15 mmφ
g Inserted into a pipe to form a composite billet. This composite billet was swaged to an outer diameter of 3 mmφ, and further rolled to finish into a tape-shaped wire rod having a thickness of 1.5 mm and a width of 4 mm. This tape-shaped wire was pressed continuously in the longitudinal direction by a pressing jig as shown in FIG. 1 to finish a tape-shaped wire having a thickness of 0.2 mm and a width of about 7 mm. . The obtained tape-shaped wire is placed in an oxygen stream at 850 ° C.
X50h heat treatment was performed to obtain a ceramic superconducting conductor. As a result of measuring the Jc of this ceramic superconductor in an O magnetic field in liquid nitrogen, it was found that the Jc was 14500 (A / cm).
² ) Excellent characteristics were obtained. The obtained tape-shaped ceramic superconducting conductor was coated with an outer diameter of 5 mmφ as shown in FIG.
A coil was formed by winding 25 turns around the metal core material A. When the generated magnetic field of the coil at the liquid helium temperature was measured, excellent characteristics of 1980 (G) were obtained.

[0011]

Embodiment 2 Bi ₂ O ₃ , PbO, SrCO ₃ , CaC
o ₃ , CuO primary raw material powder in molar ratio of 1.6: 0.4:
After mixing and mixing at a ratio of 2: 2: 3, the mixture was calcined at 800 ° C. for 20 hours in an oxygen stream, and further pulverized to produce calcined particles having an average particle size of about 5 μm. This was subjected to CIP molding to form a round bar having an outer diameter of about 15 mmφ, and was inserted into a previously machined Ag pipe having an outer diameter of 25 mmφ and an inner diameter of 15 mmφ to obtain a composite billet. This was swaged to an outer diameter of 3 mmφ, and further rolled to a thickness of 1.5 mm.
It was finished into a tape-shaped wire rod having a width of about 4 mm. The tape-shaped wire rod was continuously and continuously pressed in a desired length in the longitudinal direction by the pressing jig shown in FIG. 1 to finish a tape having a thickness of 0.5 mm and a width of about 5 mm. The obtained tape-shaped wire was heat-treated at 840 ° C. for 50 hours in an oxygen stream to obtain a ceramic superconductor. This ceramic superconducting conductor is referred to as a sample A for the convenience of the description below. This is again pressed continuously in the longitudinal direction by a desired length in the pressing jig shown in FIG. 1 to obtain a thickness of 0.3 mm and a width of about 5.5 m.
m in the shape of a tape. The obtained tape-shaped wire was heat-treated at 840 ° C. for 50 hours in an oxygen stream to obtain a ceramic superconductor. This ceramic superconducting conductor is referred to as a sample B for the convenience of the description below. Further, pressure is applied in the same manner as the previous time using the pressing jig shown in FIG.
m and a tape-shaped wire rod having a width of about 6 mm. The obtained tape-shaped wire was heat-treated at 840 ° C. for 50 hours in an oxygen stream to obtain a ceramic superconductor. This ceramic superconducting conductor is referred to as a sample C for the convenience of the description below. This was further pressed by the pressing jig shown in FIG. 1 in the same manner as the previous time to finish a tape-shaped wire rod having a thickness of 0.1 mm and a width of about 6.5 mm. The obtained tape-shaped wire was heat-treated at 840 ° C. for 50 hours in an oxygen stream to obtain a ceramic superconductor. This ceramic superconducting conductor is referred to as a sample D for the convenience of the description below. Jc of the tape-shaped wires of Samples A to D thus obtained in liquid nitrogen was measured in an O magnetic field. The results are as shown in the following table. As is clear from the above table, it was confirmed that the characteristics were further improved by repeatedly performing the press working and the heat treatment.

[0012]

EXAMPLE 3 Using the sample C obtained in Example 2, a cable having an outer diameter of 35 mm as shown in FIG. As a result of measuring the superconducting characteristics of this cable at the temperature of liquid nitrogen, Ic = 120 (A) and Jc = 12400.
Excellent characteristics (A / cm ² ) were obtained.

[0013]

Comparative Example 1 Thickness after rolling obtained in Example 1
A 5 mm tape-shaped wire having a width of about 4 mm was pressed by the method shown in FIG. 1 to finish it to a thickness of 0.2 mm and a width of about 7 mm.
The obtained tape-shaped wire is placed in an oxygen stream at 850 ° C. × 50.
h heat treatment to obtain a ceramic superconducting conductor. As a result of measuring the Jc of this ceramic superconducting conductor in liquid nitrogen in an O magnetic field, it was 14000 (A / cm ² ), but the width was 6.5 to 7.3 mm as shown in FIG. Shape.

[0014]

Comparative Example 2 Thickness obtained by rolling in Example 2.
A 5 mm tape-shaped wire having a width of about 4 mm was pressed by the method shown in FIG. 1 to finish it to a thickness of 0.2 mm and a width of about 7 mm.
The obtained wire was heat-treated at 850 ° C. for 50 hours in an oxygen stream to obtain a ceramic superconductor. As a result of measuring the Jc of the ceramic superconducting conductor in liquid nitrogen in an O magnetic field, it was 12000 (A / cm ² ), but the width was 6.4 to 7.4 mm as shown in FIG. Shape. Further, a cable as shown in FIG. 5 was prototyped by using this, and its characteristics were evaluated.
5 (A) and Jc = 8500 (A / cm ² ), which were inferior to those according to the production method of the present invention.
This is the result of the tape-shaped ceramic superconductors slightly overlapping each other.

[0015]

According to the manufacturing method of the present invention, a ceramic superconducting conductor having excellent shape and superconducting properties and applicable to cables, magnets and the like can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a method for manufacturing a ceramic superconductor of the present invention.

FIG. 2 shows a second example of a pressing jig used in the manufacturing method of the present invention.
The front view which shows an example.

FIG. 3 shows a third example of a pressing jig used in the manufacturing method of the present invention.
FIG.

FIG. 4 shows a fourth example of a pressing jig used in the manufacturing method of the present invention.
FIG.

FIG. 5 is a perspective view of a cable using a ceramic superconducting conductor manufactured by the manufacturing method of the present invention.

FIG. 6 is a perspective view of a spiral magnet using a ceramic superconducting conductor manufactured by the manufacturing method of the present invention.

FIG. 7 is a plan view of a tape-shaped ceramic superconducting conductor manufactured by the conventional manufacturing method shown in FIG.

8 (a), 8 (b), 8 (c) and 8 (d) are explanatory views of a conventional method for manufacturing a ceramic superconductor.

[Explanation of symbols]

 Reference Signs List 1 ceramic raw material 2 metal 3 composite

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Naoki Uno 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (56) References JP-A-2-183918 (JP, A) JP-A-Hei 2-199721 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01B 13/00 H01B 12/04 H01B 12/10

Claims (1)

(57) [Claims] 1. A ceramic superconductor which forms a ceramic superconductor by forming a ceramic superconductor into a ceramic superconductor after subjecting a composite 3 of a ceramic raw material 1 and a metal 2 to be a superconductor to a desired shape and then reducing the diameter of the composite 3 to a desired shape. In the method for producing a conductor, the composite 3 is pressed in the thickness direction while restraining an arbitrary length of the composite 3 to have a desired width, and after the processing is sequentially performed in the length direction of the composite 3, A method for producing a ceramic superconducting conductor, comprising heat-treating the composite 3 to make the ceramic raw material 1 a superconductor.