JPH0589730A - Manufacture of multilayer ceramic superconductive conductor - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a multilayer ceramic superconductive conductor with small dispersion and excellent superconductive characteristic. CONSTITUTION:A required number of tape materials 3 having the structure of covering a raw material layer 1 which can form a ceramic superconductor with a metal material are laminated with hard metallic tapes 4 being interposed between adjacent tape materials 3, and the resulting laminated body 5 is inserted to a metallic pipe 6 to form a multilayered composite billet 7. The multilayer composite billet 7 is repeatedly subjected to processes of drawing and heating treatment a desired times to manufacture a multilayer ceramic superconductive conductor. When the multilayer composite billet 7 is drawn, the compressing force by drawing is uniformly and sufficiently added to the tape materials 3 through the hard metallic tapes 4, so that the internal ceramic superconductor layer has an uniform form and satisfactory crystal orienting property. Thus, a ceramic superconductive conductor 8 with small dispersion and excellent superconductive characteristic can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a multilayer ceramic superconducting body which has excellent superconducting properties and is suitable as a conductor for magnets and cables.

[0002]

2. Description of the Related Art In recent years, Y- which exhibits superconductivity at liquid nitrogen temperature
Ba-Cu-O system, Bi- (Pb) -Sr-Ca-Cu
Ceramic superconductors such as -O type and Tl-Ba-Ca-Cu-O type have been found, and researches for practical use have been advanced in various fields. By the way, since these ceramics superconductors are fragile, in order to process them into a wire or the like, for example, a raw material (hereinafter abbreviated as raw material) which can be made into a ceramics superconductor can be formed on a metal pipe such as Ag or Cu which has high workability. Yes.)
To prepare a composite billet, and then draw and process this composite billet to form a wire material having a desired shape, and then subject this wire material to a predetermined heat treatment to react the raw material with a superconductor. The processing method is used. In this composite processing method, the wire material has a circular cross section, an elliptical cross section,
It is processed into an arbitrary shape such as a square or tape. Then, for example, the tape-shaped wire material is laminated in a plurality of layers in parallel, concentrically or spirally, and then these laminated bodies are filled in a separately prepared pipe made of Ag to obtain a multilayer composite. A billet is formed, and these multi-layer composite billets are subjected to the drawing process and the heat treatment in the same manner as described above to produce a multi-layer ceramic superconducting body.

[0003]

However, in the above-mentioned multilayer ceramic superconducting body, since a material such as soft Ag is used as the metal material to be coated, a sufficient compressive force is applied to the raw material layer during stretching. In the resulting multilayer ceramic superconductor, as shown in FIG. 2, the ceramic superconductor layer 8 has a poor shape and is poor in crystal orientation.
Therefore, there has been a problem that the superconducting characteristics have low values with large variations. This means that in order to obtain high performance, it is necessary to repeat the steps of stretching and heat treatment B
There has been a particularly serious problem in the production of i-based ceramics superconductors.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of intensive studies in view of the above circumstances, and an object of the present invention is to produce a multilayer ceramic superconducting body with small variations and excellent superconducting properties. To provide a method. That is, according to the present invention, a required number of tape-shaped raw materials having a structure in which a raw material layer that can be a ceramics superconductor is coated with a metal material are laminated, and this laminated body is inserted into a metal pipe to form a multilayer composite billet. In the method for producing a multilayer ceramic superconducting body in which the multilayer composite billet is repeatedly subjected to a drawing process and a heat treatment process as many times as desired, a required number of tape-shaped materials are hard metal tapes between adjacent tape-shaped materials. It is characterized in that they are laminated and integrated by interposing.

According to the method of the present invention, a required number of tape-shaped materials each having a raw material layer coated with a metal material are laminated with a hard metal tape interposed between adjacent tape-shaped materials, and the laminated body is made of metal. Inserted in a pipe to form a composite billet, and when the composite billet was stretched, the compressive force by the stretching process was applied uniformly and sufficiently to the raw material layer through the hard metal tape. It is a thing. Thus, in the obtained multilayer ceramic superconducting body, the ceramic superconducting layer has a uniform shape and is rich in crystal orientation, and therefore, the superconducting property has a high value with little variation. In the method of the present invention, the hard metal tape is preferably a hard and excellent oxygen-permeable metal material, for example, an Ag alloy in which Ag contains at least one alloy element such as Pd, Rh, Pt, and Ir. Is.

The multilayer ceramic superconducting body of the present invention is
For example, a raw material is filled in a metal pipe to form a composite billet, and the composite billet is repeatedly subjected to a stretching process and a heat treatment process a desired number of times to form a tape-shaped raw material, and then shown in FIGS. As described above, a plurality of tape-shaped raw materials 3 (Fig. A) in which the above-mentioned raw material layer 1 is covered with the metal coating layer 2 are stacked, and a hard metal tape 4 is interposed between the adjacent tape-shaped raw materials 3. Then, the laminated body 5 is inserted into a rectangular metal pipe 6 to produce a multi-layer composite billet 7 (Fig. C). Then, the multi-layer composite billet 7 is stretched and heat-treated. The steps are repeated a desired number of times to manufacture a multilayer ceramic superconducting body 9 in which a required number of ceramic superconducting layers 8 are laminated (FIG. 2). In the above, the composite billet is produced by inserting a required number of tape-shaped materials into a rectangular metal pipe, and then inserting a hard metal tape into the gap between the tape-shaped materials to interpose it. You can also

In the method of the present invention, the raw materials include the above-mentioned Y-based, Bi-based, Tl-based ceramics superconductors, and intermediates that react with the ceramics superconductor by heat treatment in an oxygen-containing atmosphere, For example, a mixture of constituent elements of a ceramics superconductor, or a coprecipitation mixture, or primary raw material powders of oxides or carbonates of the above constituent elements are mixed in predetermined amounts to form a mixed raw material, and the mixed raw material is calcinated. Oxygen-deficient complex oxides are used. Further, in order to fill the raw material into the metal pipe, in addition to the method of directly filling the raw material, the raw material is preliminarily molded into a predetermined shape by the CIP method or the like, or the molded body is further heated and sintered. A filling method is used. When the raw material is processed into a compact or a sintered body and then filled, the density of the obtained ceramic superconducting body is increased, and the characteristics such as Jc are further improved. In the method of the present invention, the stretching process applied to the above-mentioned multilayer composite billet, extrusion, drawing, swaging, rolling, forging, can be applied any processing method such as press compression, but the rolling method or press compression method. It is preferable because the density of the superconductor layer can be further increased. The heat treatment applied to the composite billet is carried out in order to react the raw material with the ceramic superconductor, and the heating temperature is usually 820 to 820 in the case of Bi-based ceramic superconductor.
The temperature range is 885 ° C. The final heat treatment is
It is preferable to form the drawn material after forming it into a magnet coil or the like, because the ceramic superconductor layer inside is unlikely to be cracked or the like.

[0008]

In the method of the present invention, a required number of tape-shaped materials each having a raw material layer coated with a metal material are laminated with a hard metal tape interposed between adjacent tape-shaped materials, and the laminate is formed. Is inserted into a metal pipe to produce a multi-layer composite billet, and the multi-layer composite billet is subjected to repeated stretching and heat treatment steps a desired number of times to produce a multi-layer ceramic superconducting body. In doing so, the compressive force due to the stretching process is applied uniformly and sufficiently to the raw material layer through the hard metal tape, thus,
The ceramic superconducting layer of the obtained multilayer ceramic superconducting body has a uniform shape and is rich in crystal orientation, and the superconducting characteristics have small variations and high values.

[0009]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 Bi ₂ O ₃ , PbO, SrCO ₃ , CaCO ₃ , CuO
Primary raw material powders such as Bi: Pb: Sr: Ca:
Cu was mixed so that the atomic ratio was 1.6: 0.4: 2: 2: 3, and the mixed powder was calcined in the air at 800 ° C. for 50 hours, and then the calcined body was crushed. Average particle size is about 5
It was calcined powder of μm. This calcined powder is then 25m in outer diameter
A round bill pipe made of Ag with mφ and an inner diameter of 20 mmφ was filled to prepare a composite billet. Next, this composite billet is swaged and rolled to have a width of 7 mm and a thickness of 1 mm.
Of the tape-shaped material, and then 6 pieces of the tape-shaped material are heat-treated in the atmosphere at 830 ° C. for 50 hours, and then a 0.2 mm-thick Ag alloy hard tape is placed between the tape-shaped materials. A with an outer diameter of 9 mm and an inner diameter of 7 mm
The multi-layer composite billet was produced by inserting it into a square pipe made of g. Next, this multilayer composite billet is rolled to 4 m.
No m-square line material, then 83 in the air
Heat treatment was performed at 0 ° C. for 50 hours to form a multilayer ceramic superconducting body A, and the multilayer ceramic superconducting body A was further rolled to form a 3 mm square wire material. A multilayer ceramic superconducting body B was manufactured by performing heat treatment for a period of time. The Ag alloy hard tape interposed between the tape-shaped materials has an alloy concentration of 1,
3,5% Ag-Pd alloy, Ag-Rh alloy, Ag-P
Either Ag alloy of t alloy and Ag-Ir alloy was used. Comparative Example 1 A multilayer ceramic superconductor was manufactured by the same method as in Example 1, except that a soft Ag tape was used instead of the hard Ag alloy tape between the tape-shaped wire rods. .. Each of the multilayer ceramic superconductors obtained in this way was tested in liquid nitrogen (77
K), the critical current (Ic) was measured under 0 magnetic field. Regarding the ceramic superconductor B, after measuring Ic, the crystal orientation of the ceramic superconductor layer was investigated by the X-ray diffraction method. Further, the shape of the ceramic superconductor layer was observed.
The results are shown in Table 1.

[0010]

[Table 1]

As is clear from Table 1, the method products of the present invention (Nos. 1 to 14) are rich in crystal orientation and have a good shape of the superconductor layer, and thus have a high Ic and a small variation. It was Regarding the influence of the strength of the Ag alloy, that is, the alloy concentration, the one having the alloy concentration of 3% (No. 2, 5, 8, 11) had the highest Ic. Those with low alloy concentration (No.1,4,7,10) do not have sufficiently high crystal orientation, and those with high alloy concentration (No.3,6,9,1)
In 2), the electrical and thermal conductivity of the metal matrix was lowered and the quenching resistance was deteriorated, and in each case, Ic was somewhat lowered. In addition, the drawing process and the heat treatment process were additionally performed once.
The ceramic superconducting material of square mm has improved Ic as compared with that of 4 mm square. Almost no increase in variation was observed. On the other hand, the comparative example product (No. 15) had a low Ic and a large variation. This is because the compressive force was not sufficiently applied to the raw material layer inside the composite billet during the stretching process, and the crystal orientation decreased. In addition, although the Ic of the 3 mm square one was improved as compared with the 4 mm square one, the variation was large. This is because the ceramic superconductor layer undergoes uneven deformation due to the increased processing amount. Although the case where the composite billet in which the tape-shaped materials are laminated in parallel is used has been described above, the same effect can be obtained even when the method of the present invention is applied to the composite billet in which the tape-shaped materials are concentrically or spirally laminated. It is a thing.

[0012]

As described above, according to the method of the present invention, it is possible to obtain a multilayer ceramic superconducting body having excellent superconducting characteristics with a small variation, and to exert a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing an example of a method of producing a multilayer composite billet used in the present invention.

FIG. 2 is a cross-sectional view of a multilayer ceramic superconductor manufactured by a conventional method.

[Explanation of symbols]

 1 Raw Material Layer 2 Metal Covering Layer 3 Tape Material 4 Hard Metal Tape 5 Laminate 6 Metal Pipe 7 Multilayer Composite Billet 8 Ceramics Superconductor Layer 9 Multilayer Ceramics Superconductor

Claims (1)

[Claims] 1. A multilayer composite billet is manufactured by laminating a required number of tape-shaped raw materials having a structure in which a raw material layer that can be a ceramics superconductor is covered with a metallic material, and inserting the laminated body into a metallic pipe. Then, in the method for producing a multilayer ceramic superconducting body in which the steps of stretching and heat treatment are repeatedly performed on this multilayer composite billet a desired number of times, a required number of tape-shaped materials are formed by applying a hard metal tape between adjacent tape-shaped materials. A method of manufacturing a multilayer ceramic superconductor characterized by interposing and interposing a laminate.