JPH04269407A - Manufacture of ceramic superconductive conductor - Google Patents

Abstract

PURPOSE:To provide manufacture of a ceramic superconductive conductor in a shape usable for a magnet and a cable and moreover excellent in superconductive characteristic. CONSTITUTION:A complex 3 consisting of a ceramics raw material 1 to servo as a superconductor and a metal 2 is subjected to press processing while its optional length is restrained to become a desired width, and this processing is progressively performed along the length direction of the complex 3 followed by performing heat treatment of the same complex 3 in order to make aforesaid ceramic raw material 1 a superconductor.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to cables, magnets,
The present invention relates to a method of manufacturing a ceramic superconducting conductor that can be used as a current lead or the like.

0002

[Prior Art] In recent years, Y-Ba-Cu-O system, Bi-S
Ceramic superconductors with Tc exceeding the liquid nitrogen temperature are known, such as r-Ca-Cu-O type and Tl-Ba-Ca-Cu type. Molding of such ceramic superconducting conductors into various shapes is being considered for use and application in various fields. One such method is, for example, a method of molding it into a linear body. In that case, a metal sheath method has conventionally been generally used. This involves filling a metal pipe with a ceramic raw material that will become a superconductor, reducing the diameter of the pipe to the desired shape and dimensions, and then subjecting it to a prescribed heat treatment to turn the ceramic raw material into a ceramic superconductor. be. The shape of the linear body may be round, oval, or polygonal in cross section, or a multi-core shape made by bundling multiple of these, and even a concentric cylindrical or spiral shape with ceramic superconductor inside the metal. Prototypes of multi-layered structures are being considered. As the diameter reduction method, conventional plastic working methods such as extrusion, rolling, swaging, and drawing are directly applied depending on the shape of the linear body to be obtained. As the metal, materials with excellent thermal conductivity and electrical conductivity, such as Ag, Ag alloy, Cu, and Cu alloy, can be used, but Ag and Ag alloy are often used because of their oxygen permeability.

Recently, the use of such a tape multicore ceramic superconductor in a cable as shown in FIG. 5 has been studied. The cable shown in FIG. 5 has a plurality of tape multicore ceramic superconductors B arranged around a metal rod or pipe A. In this case, a tape multicore ceramic superconductor B with a high Jc is desired, but in order to obtain a ceramic superconductor with a high Jc, crystal orientation of the ceramic superconductor is required, and to achieve this, It is necessary to make the thickness of the superconductor as thin as possible. Conventionally, relatively high superconducting properties have been obtained with rolled tape-shaped conductors, but the Jc value is 104 (A/c
m2) was the limit. In order to improve its superconducting properties, the applicant of the present application previously applied for a method for manufacturing a ceramic superconductor as shown in Figure 8 (Japanese Patent Application No. 1099-1982).
did. However, in the method for manufacturing the ceramic superconductor shown in FIG. 8, the rod-shaped composite D of ceramic raw material and metal that becomes the superconductor is processed from the thickness direction (vertical direction in the figure) as shown in FIGS. 8a to 8c. Pressure is applied using pressure molds E and F, and the following is done.
In this method, pressure is applied sequentially and continuously in the longitudinal direction of the rod-shaped composite D as shown in FIG. 8d.

0004

[Problems to be Solved by the Invention] However, in the method for manufacturing a ceramic superconducting conductor shown in FIG. Since both sides of D in the width direction are open,
The pressurized rod-shaped composite D expands locally in the width direction as shown in FIG. 7, and the resulting tape-shaped superconducting conductor G
As shown in FIG. 7, there was a problem in that it was difficult to keep the tape width constant. This tape-shaped superconducting conductor G with non-uniform tape width is, for example, connected to a cable H as shown in FIG.
The tape can be used as a multicore ceramic superconductor B, or it can be wound spirally to form a magnet I as shown in Figure 6.
When used for this purpose, there are problems in that it becomes difficult to wind in alignment and the shape deteriorates, and that the tape-shaped superconducting conductors G overlap each other and the superconducting properties deteriorate due to stress.

[0005]

[Object of the Invention] The object of the present invention is to provide a method for manufacturing a ceramic superconducting conductor that has a shape that can be used for cables as shown in Fig. 5 and magnets as shown in Fig. 6, and that has excellent superconducting properties. It is about providing.

[0006]

[Means for Solving the Problems] The present invention was developed as a result of various experiments in order to improve the above-mentioned problems. The method for manufacturing the ceramic superconducting conductor of the present invention is shown in FIG.
As shown in the figure, a given length of a composite 3 of a ceramic raw material 1 and a metal 2 that will become a superconductor is pressurized in the thickness direction while restraining the sides in the width direction, and this pressure is applied to the length of the composite 3. The present invention is characterized in that the composite body 3 is subjected to a heat treatment to convert the ceramic raw material 1 into a superconductor.

In the method for manufacturing a ceramic superconducting conductor of the present invention, a ceramic raw material 1 that will become a superconducting material is first prepared. As a method for obtaining the raw material 1, conventional means can be applied as is. For example, it can be obtained by blending and mixing primary raw material powders such as oxides, carbonates, etc. containing elements constituting the superconductor to a desired composition, calcining the mixture, and then pulverizing it. Alternatively, it can be obtained by heating and melting the raw material powder as described above, rapidly cooling it, and pulverizing it. The thus obtained calcined powder (ceramic raw material to become a superconductor) 1 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 it may be molded into a desired shape by compaction molding, CIP molding, etc. and then inserted, or it may be sintered and then inserted to form the composite body 3. It is possible. in this case,
The raw material 1 can also be configured to have a multi-core shape or a multi-layered shape. The size of the complex 3 can be determined as appropriate. For example, if the composite body 3 is large in size, it is plastically worked to a predetermined size and then molded using a pressing jig 5 to obtain the 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 the composite body 3 is molded to an arbitrary length, the composite body 3 is press-molded sequentially and continuously in the length direction. The speed of this compression molding can be selected as appropriate.

[0008] The pressurizing jig 5 has a portion thereof recessed to form a pressurizing portion 6. The width a of this pressure part 6 is the width of the obtained tape.
The width should be approximately the same as the width of the loop-shaped wire. Pressure section 6 of pressurization jig 5
The depth b is determined depending on the thickness of the tape-shaped wire to be obtained. When pressurized by this pressurizing jig 5, both sides of the composite 3 in the width direction are restrained by both sides 7 and 8 in the width direction of the pressurizing part 6, so that the composite 3 is pressurized in its thickness direction. However, it does not protrude in the width direction of the composite body 3. The illustrated embodiment is an example in which the shape of the ceramic superconductor obtained is a tape-like linear body, but the shape of the ceramic superconductor obtained by the method of manufacturing a ceramic superconductor of the present invention is limited to this. For example, the shape may be a vertically long ellipse as shown in FIG. 2, a horizontally long ellipse as shown in FIG. 3, a polygon as shown in FIG. 4, or the like. In the present invention, the tape-like linear body obtained as described above is heat treated to make the ceramic raw material 1 in the composite body 3 into a superconducting conductor. The above explanation is for the case where compression processing and heat treatment are performed only once, but in the present invention, compression processing and heat treatment are repeated two or more times as shown in FIG. If the material is further heat-treated after being made into a shape, the superconducting properties will be further improved.

[0009]

[Function] Since the tape-shaped ceramic superconducting conductor obtained by the manufacturing method of the present invention has a uniform width, it can be used as a metal round bar, pipe, etc. (metal core material) A as shown in FIG. By winding the ceramic superconducting conductors, it becomes possible to wind them in an aligned manner, and the ceramic superconducting conductors do not overlap with each other, resulting in a cable or magnet having an excellent shape and superconducting properties. Furthermore, when spirally wound as shown in FIG. 6, the bending strain applied to the ceramic superconductor becomes small, so that the superconducting properties do not deteriorate.

0010

[Example 1] Bi2 O3, SrCO3, CaCO
3. After blending and mixing primary raw material powders such as CuO to a molar ratio of 2212, heat at 820°C in an oxygen stream.
It was calcined for 20 hours and further crushed to produce calcined powder (raw material for ceramic superconductor) with an average particle size of about 5 μm. This is CIP molded into a round bar with an outer diameter of about 15 mmφ, which is pre-machined to an outer diameter of 25 mmφ and an inner diameter of 15 m.
It was inserted into a mφ Ag pipe to form a composite billet. This composite billet was swaged to an outer diameter of 3 mm, and then rolled to a tape with a thickness of 1.5 mm and a width of 4 mm.
Finished in a loop-shaped wire rod. This tape-shaped wire rod was sequentially and continuously pressed in the longitudinal direction using a pressure jig as shown in Figure 1, and finished into a tape-shaped wire rod with a thickness of 0.2 mm and a width of about 7 mm. . The obtained tape-shaped wire was heated in an oxygen stream for 8
A ceramic superconducting conductor was obtained by heat treatment at 50°C for 50 hours. About this ceramic superconductor In liquid nitrogen,
As a result of measuring Jc in the O magnetic field, it was 14500 (A/
cm2) excellent properties were obtained. The obtained tape-shaped ceramic superconductor has an outer diameter of 5 as shown in FIG.
A coil was constructed by winding 25 turns around a metal core material A having a diameter of mm. When the magnetic field generated by this coil at liquid helium temperature was measured, excellent characteristics of 1980 (G) were obtained.

[0011]

[Example 2] Bi2 O3, PbO, SrCO3,
The molar ratio of primary raw material powder of CaCo3 and CuO is 1.6:
After blending and mixing in a ratio of 0.4:2:2:3,
The mixture was calcined at 800° C. for 20 hours in an oxygen stream and further crushed to produce calcined grains with an average particle size of about 5 μm. This was CIP-molded into a round bar with an outer diameter of about 15 mmφ, and inserted into a previously machined Ag pipe with an outer diameter of 25 mmφ and an inner diameter of 15 mmφ to form a composite billet. This has an outer diameter of 3m
It was swaged to mφ and further rolled to a tape-shaped wire with a thickness of 1.5 mm and a width of about 4 mm. This tape-shaped wire rod was press-worked sequentially and continuously in desired lengths in the longitudinal direction using the pressing jig shown in Fig. 1, and the thickness was 0.5 mm.
It was finished into a tape shape with a width of about 5 mm. The obtained tea
The wire rod was heat-treated at 840° C. for 50 hours in an oxygen stream to obtain a ceramic superconducting conductor. This ceramic superconducting conductor will be referred to as sample A for convenience of explanation later. This was again successively pressed in the desired length in the longitudinal direction using the pressing jig shown in Figure 1, and the thickness was 0.3 mm and the width was approximately 5 mm.
．． It was finished into a 5mm tape-shaped wire. The obtained tape-shaped wire was heat-treated at 840° C. for 50 hours in an oxygen stream to obtain a ceramic superconducting conductor. This ceramic superconducting conductor will be referred to as sample B for convenience of explanation later. Further, pressure was applied in the same manner as before using the pressure jig shown in Fig. 1 until the thickness was 0.
It was finished into a tape-shaped wire with a diameter of 2 mm and 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 superconducting conductor. This ceramic superconducting conductor will be referred to as sample C for convenience of explanation later. This was further pressurized using the pressure jig shown in Figure 1 in the same manner as before, and a tape with a thickness of 0.1 mm and a width of about 6.5 mm was obtained.
Finished in a loop-shaped wire rod. The obtained tape-shaped wire rod was heat-treated at 840° C. for 50 hours in an oxygen stream to obtain a ceramic superconducting conductor. This ceramic superconductor will be referred to as sample D for convenience of explanation later. Jc in the O magnetic field was measured for the tape-shaped wire rods of Samples A to D thus obtained in liquid nitrogen. The results are shown in the table below. As is clear from the table above, it was found that the properties were further improved by repeatedly performing the press working and heat treatment.

0012

[Example 3] Using Sample C obtained in Example 2, a cable having an outer diameter of 35 mm as shown in FIG. 5 was fabricated. As a result of measuring the superconducting properties of this cable at liquid nitrogen temperature, Ic = 120 (A), Jc = 12400 (
Excellent characteristics of A/cm2) were obtained.

[0013]

[Comparative Example 1] Thickness after rolling obtained in Example 1: 1.
A tape-shaped wire rod of 5 mm in diameter and about 4 mm in width was pressed by the method shown in FIG. 1 to have a thickness of 0.2 mm and a width of about 7 mm. The obtained tape-shaped wire rod was heated at 850°C x 50°C in an oxygen stream.
h heat treatment to obtain a ceramic superconducting conductor. The Jc of this ceramic superconductor was measured in liquid nitrogen in an O magnetic field and was found to be 14,000 (A/cm2), but the width was 6.5 to 7.3 mm as shown in Figure 2.
It had a wavy shape.

[0014]

[Comparative Example 2] Thickness obtained by rolling in Example 2: 1.
A tape-shaped wire rod of 5 mm in diameter and about 4 mm in width was pressed by the method shown in FIG. 1 to have a thickness of 0.2 mm and a width of about 7 mm. The obtained wire rod was heat-treated at 850° C. for 50 hours in an oxygen stream to obtain a ceramic superconducting conductor. The Jc of this ceramic superconducting conductor in an O magnetic field in liquid nitrogen was measured to be 12000 (A/cm2).
As shown in FIG. 2, it had a wavy shape with a width of 6.4 to 7.4 mm. In addition, we made a prototype cable as shown in Fig. 5 using this, and evaluated its characteristics, and found that Ic=
85 (A), Jc=8500 (A/cm2),
It was inferior to that produced by the production method of the present invention. This is the result of the tape-shaped ceramic superconducting conductors slightly overlapping each other.

[0015]

According to the manufacturing method of the present invention, a ceramic superconducting conductor can be obtained which has excellent shape and superconducting properties and can be applied to cables, magnets, etc.

[Brief explanation of the drawing]

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

[Fig. 2] A second pressurizing jig used in the manufacturing method of the present invention.
FIG. 3 is a front view showing an example.

FIG. 3: The third pressurizing jig used in the manufacturing method of the present invention.
FIG.

FIG. 4 A fourth pressurizing jig used in the manufacturing method of the present invention.
FIG.

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

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

7 is a plan view of a tape-shaped ceramic superconductor manufactured by the conventional manufacturing method shown in FIG. 8. FIG.

FIGS. 8a, b, c, and d are explanatory diagrams of a conventional method for manufacturing a ceramic superconducting conductor.

[Explanation of symbols]

1 Ceramic raw materials 2 Metal 3 Complex

Claims (1)

[Claims] 1. A ceramic superconductor in which a composite body 3 of a ceramic raw material 1 and a metal 2 to be a superconductor is reduced in diameter to a desired shape, and then the composite body 3 is heat treated to make the ceramic raw material 1 a ceramic superconductor. In the method for manufacturing a conductor, an arbitrary length of the composite body 3 is compressed in the thickness direction while being constrained to a desired width, and after this process is sequentially performed in the length direction of the composite body 3, A method for producing a ceramic superconductor, characterized in that the composite 3 is heat-treated to make the ceramic raw material 1 a superconductor.