JPH0395806A - Superconductive conductor, its manufacture and superconducting coil formed by using the same superconductive conductor - Google Patents

Abstract

PURPOSE:To obtain a superconductive conductor having high critical current density which can be efficiently manufactured by a method wherein the superconductive conductor layer is composed of a two-dimensional superconductor and a plane perpendicular to a C axis high in a critical magnetic field is placed in parallel to an electrifying direction of the superconductive conductor. CONSTITUTION:A superconductive conductor is a tape-like superconductive conductor with a cross section of a straight angle with a superconductor layer 3 buried in a metal matrix 1, wherein a widthwise direction of the cross section of the superconductor layer 2 is placed in parallel to a widthwise plane of the superconductive conductor, ratio l/d of widthwise length l to thickness (d) of the superconductor layer 2 is within a range of 10 to 10<4>, the superconductor layer 2 is composed of a twodimensional superconductor whose critical magnetic field is larger in a direction perpendicular to a C axis than in a direction parallel to the C axis, and an angle made by a perpendicular line on the widthwise plane of the tape-like superconductive conductor and the C axis on a widthwise part of the superconductor layer 2 is 15 deg. or smaller. Thus a direction perpendicular to the C axis with a high critical magnetic field of the superconductor layer is aligned with a direction for applying the magnetic field so as to obtain high critical current density or high magnetic field generation.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a composite superconductor obtained by embedding a compound superconductor such as a ceramic superconductor in a metal matrix, a method for manufacturing the same, and a method using the superconductor. This article is about superconducting coils that have taken shape.

．． [Prior art and its problems] NbTi, NbsSn, Nb. Intermetallic compounds such as ACV and Ga, and metals such as Nb and Pb are used in superconducting magnetographs, magnetic shields, coaxial cables, cavities, etc. using cryogenic refrigerants such as liquid He. However, these metal materials are limited in terms of resources and use He for cooling, resulting in high costs and limited applications.

In response to these problems, in recent years, materials with a high temperature (T,) that can become superconducting using inexpensive cooling media have been discovered, and research on their practical application is actively progressing in various fields. Therefore, the above high T,
The substance is Lag-xBa.T, of 30-45K. cu
04 and La2-xsr. cuoa, or T, is ~95K
Y (Dy..Er,Ho)BagCu. O, -δ,
Or Bizs rtCaCu with Tc of 80-110K
．． 08, B of B its rgcat Cu30+o
i-Sr-Ca-Cu-0 system, or T, is 90-125
K's Tj! ．． Ba. CaCu. ○s, T12BazC
azCus○1. , T I B az C az
Cu? ○、． , etc., and these oxide superconductors are produced by, for example, kneading the above-mentioned super t4 powder with an organic binder to form a paste, and The super t-conductor powder is shaped by direct extrusion or screen printing, or
It is made by filling a pipe or the like and stretching it to form a conductor of a desired shape. Furthermore, prototype coils using these conductors have been manufactured, and various studies are being conducted to put them into practical use.

By the way, ceramic superconductors such as those described above have strong crystal anisotropy, and for example, regarding the critical magnetic field, the critical magnetic field in the direction perpendicular to the C axis is 5 to 50 times larger than the critical magnetic field in the parallel direction, so it is so-called two-dimensional. It is a superconductor. The JC of a superconductor having this superconductor as a component or the magnetic field generated by a solenoid coil or the like using this superconductor is greatly influenced by the crystal orientation of the superconductor.

However, in conventional superconductors, the arrangement of the superconductor layers constituting the superconductor is random with respect to crystal orientation, and therefore such superconductors have a low specific field current density (J,). There was a problem that a high generated magnetic field could not be obtained with a coil using a conductor. [Means for Solving the Problems] The present invention was made as a result of intensive research in view of the above situation, and its purpose is to efficiently manufacture a high J superconductor and the superconductor. The object of the present invention is to provide a method and a superconducting coil capable of generating a high magnetic field.

That is, the invention of claim 1 is a tape-shaped superconductor having a rectangular cross section in which a superconductor layer is embedded in a metal matrix, and the above-mentioned super TH. The conductor layer is arranged such that the width direction of its cross section is parallel to the wide surface of the tape-shaped superconductor, and the width direction length i of the superconductor layer parallel to the wide surface of the tape-shaped superconductor and the superconductor layer. The ratio 1/d to the thickness d is in the range of 10-104, and the superconductor layer is made of a two-dimensional superconductor whose critical magnetic field is larger in the direction perpendicular to the C-axis than in the direction parallel to the C-axis. , a superconductor characterized in that the angle between the perpendicular to the wide surface of the tape-shaped superconductor and the C axis of the widthwise portion of the superconductor layer is 156 or less.

Generally, when a superconductor is used by being wound into a coil, a magnetic field is applied to the superconductor from the lateral direction. The superconductor of the present invention has a rectangular tape-like shape, and the width direction of the superconductor layer constituting the tape-like conductor is arranged parallel to the wide surface of the tape-like conductor. and by orienting the C-axis of the width direction portion of the superconductor layer in the perpendicular direction of the wide surface of the tape-shaped conductor,
The direction perpendicular to the C-axis in which the critical magnetic field of the superconductor layer is high is made to coincide with the direction in which the magnetic field is applied, so that a high J or generated magnetic field can be obtained.

In the above, the reason why the angle between the perpendicular to the wide surface of the superconductor and the C-axis of the superconductor surrounding the conductor was limited to 156 or less is that if it exceeds 15'', the angle is perpendicular to the C-axis of the superconductor layer. The difference between the magnetic field application direction and the direction J
, or because the generated magnetic field decreases significantly.

In this invention, the ratio l/d of the width direction length l of the superconductor layer parallel to the wide surface of the superconductor and the thickness d of the superconductor layer in the cross section of the tape-shaped superconductor is limited to 10-104. The reason is that if the above-mentioned limit value is exceeded, it becomes difficult to keep the angle between the perpendicular to the wide surface of the superconductor and the C-axis of the superconductor layer within 15 degrees, and as a result, Jc and the generated magnetic field strength decrease. This is also because it becomes unstable.

The superconductor of the present invention has a superconductor layer 2 embedded in a tape-shaped metal matrix 1 having a rectangular cross section, as shown in the cross-sectional view of FIG. 1A, for example. The width direction of 2 is arranged parallel to the wide surface of the tape-shaped metal matrix 1, and the length 1 in the width direction parallel to the wide surface of the tape-shaped metal matrix 1 of the superconductor layer and the thickness of the superconductor layer. The ratio N/d is in the range of 10 to 104. The superconductor shown in Figure B has a structure in which the end face of the superconductor layer 2 is exposed from the side surface of the metal matrix 1. Body layer 2 is embedded.

In this invention, the above-mentioned oxide superconductor is applied to the superconductor layer constituting the superconductor, and these superconductors are two-dimensional superconductors as described above, and the critical magnetic field ( trcz) is parallel to the critical magnetic field (Hc
x/), which is 5 to 50 times larger than T in liquid He.
{Includes cases where the ct exceeds the IOT.

In this invention, the metal matrix includes Ag1Au,
Metals with excellent heat conductivity such as Cu and Affi are used, and depending on the purpose, the above metals are reinforced with other metal materials. The invention according to claim 3 is a coil formed using the superconductor according to claim 1, wherein the superconductor according to claim 1 is wound so that its wide surface is parallel to the direction of the generated magnetic field. It is characterized by the fact that

After the superconductor has been insulated, it can exhibit its properties to the best of its ability by winding it in a spring so that its wide side faces upward and downward.

The coil of the present invention can also be manufactured by the Wind & React method in which a tape-shaped body before heat treatment is wound into a coil and then heat treated. In this case, a heat-resistant insulating material is used as the insulating material.

The coil of this invention can be reinforced with SUS, Hastelloy alloy, carbon fiber, etc., or solidified with epoxy resin, etc., so as to withstand the Lawrence force during use.

Since the coil of the present invention has a flat cross-section, it is suitable for use as a solenoid or pancake-shaped coil because it is easy to manufacture.

The invention according to claim 2 is a method for manufacturing the superconductor according to claim 1, which comprises alternately laminating a superconducting substance of a superconductor or its precursor and a metal material, and stretching this laminate to form a tape having a rectangular cross section. This method is characterized in that it is made into a tape-shaped wire rod, and then this tape-shaped wire rod is subjected to a heat treatment.

As the oxide superconductor used in the method of this invention, various types of oxide superconductors as described above are widely used, and in addition, raw materials that can be used as oxide superconductors which are precursor substances of the above-mentioned oxide superconductors. Intermediates from substances to oxide superconductors can be used, such as mixtures or co-precipitated mixtures of oxide superconductor structural elements, oxygen-deficient composite oxides, or alloys of the above structural elements. These precursor substances react to form an oxide superconductor when heated in an oxygen-containing atmosphere.

The laminate used in the method of the present invention is as shown in cross-sectional views in FIGS. 2A-2. That is, the laminate shown in Figure A is one in which the gaps between tubular metal materials 3 arranged concentrically are filled with a superconducting substance 4, which is a superconductor or its precursor.
The laminate shown in FIG. 2B is a tubular metal material 3 filled with a composite formed by spirally winding a band-shaped metal material 5 and a superconducting substance 4. The laminate shown in FIG. 3C is one in which plate-shaped metal materials 6 and superconducting substances 4 are alternately laminated and filled in a tubular metal material 3. The laminate shown in FIG. 2 is a composite laminate in which four individual laminates as described above are fitted into a frame of the metal material 7.

The laminate or composite laminate is extruded, rolled, drawn, swaged, or otherwise processed into a tape-shaped body with a rectangular cross section, and then this tape-shaped body is heated in an oxygen-containing atmosphere. The superconductor is reacted and sintered to produce a superconductor. The heating temperature in the above heat treatment is preferably at least the recrystallization temperature or higher, and in some cases, a temperature at which partial melting occurs to improve crystal conformation. In addition, it is preferable to use an oxygen atmosphere as the heating atmosphere because this will accelerate the reaction to the superconductor. It is preferable to make slits in the metal layer on the surface of the tape-shaped body prior to the above-mentioned heat treatment, since oxygen can be sufficiently supplied to the superconductor layer.

[Effect]

The superconductor of the present invention has a superconductor layer consisting of a two-dimensional superconductor in which the critical magnetic field is large in the direction perpendicular to the C-axis and small in the direction parallel to the C-axis in a tape-shaped metal matrix with a rectangular cross section. The superconducting conductor is embedded with the direction parallel to the wide side of the metal matrix placed parallel to the wide side of the metal matrix, so the superconducting coil that is coil-amplified with the wide side of the conductor in the vertical direction will be able to apply the magnetic field that is generated during use. In contrast to the direction perpendicular to the C axis of the superconductor layer, a high J as a superconductor and a high generated magnetic field as a coil can be obtained. Moreover, since this Pa'WL conductor can be manufactured by ordinary drawing and heat treatment methods, it is easy to manufacture and has high productivity.

[Examples] The present invention will be explained in detail below using examples. Example I BfzOs, Pb○, SrCo3, CaCOs, Cub
．． The atomic ratio of Bi:Pb:Sr:Ca:Cu is 1.9
: 0.2: 2 : 1.1:2.2, and this mixed powder was heated to 860°C in the air.
゜C3H calcined material is crushed and classified to produce B i. s r. Ca Cu. O. A calcined powder was prepared.

Then, 10 voj 2% of methyl cellulose and 8 vof % of butyl cellosolve were blended with the above calcined powder as binders, and after kneading this with a roll, a tape-shaped green sheet of 0.9 m+a' was produced by the doctor blade method. Next, the above green sheet was overlapped with a 0.9 m' Ag sheet, and this was rolled into a sushi-like shape with the Ag sheet facing outward to form a bar with a diameter of 15 m. Next, this specimen was heated to 150°C to remove volatile components such as binder, and then heated to 800°C IH in the atmosphere and cooled. Next, this was filled into an Ag pipe with an inner diameter of 15 mm and a wall thickness of 2 am, and after the pipe was vacuum-sealed, HIP treatment was performed at 500°CIOOO atmospheric pressure. After that, the Ag pipe filled with the sushi roll and subjected to HIP treatment was swaged in 5 steps. This material was rolled to 0.5mm' and further rolled to 8mm.
A board material was made by cutting the material to a width of 1nI+.

The plate material was then heated in the atmosphere to 900°C for 0.25H to partially melt the oxide superconductor layer, and then heated to 860°C.
After heating at 860'C for 8H, cooling slowly until 860'C.
A plate-shaped oxide superconductor was manufactured by performing a series of heat treatments (maintaining at 20'C for 6H and cooling).

Example 2 A plate-shaped oxide superconductor was manufactured in the same manner as in Example 1, except that the thickness of the plate material obtained by rolling the material was 0.09 mm'.

Example 3 The thickness of the plate material obtained by rolling the material was 2. 0 mm'
A plate-shaped oxide superconductor was manufactured by the same method as in Example 1 except that the following steps were taken.

Example 4 The material diameter after swaging was set to 9.0 m + nφ, and this material was rolled and slit to 0.08 mm'
A plate-shaped oxide superconductor was manufactured in the same manner as in Example 1, except that a temporary material of 5" was used.

Comparative Example 1 In Example 1, the 5.0ms+φ material was wire drawn to 0
A linear oxide superconductor was manufactured in the same manner as in Example 1, except that the wire rod had a diameter of 5 mm.

Comparative Example 2 In Example 1, the swaging of the Ag vibrator was
A plate-shaped oxide superconductor was manufactured in the same manner as in Example 1, except that the 15 nm+φ material was rolled to form a plate material of 0.02 mIfi' x 23m+a'.

Comparative Example 3 In Example 1, the thickness of the green sheet was 4.2 t.
rm, and the thickness of the Ag sheet 1. which is overlapped with the above green sheet is 1.rm. A material with a diameter of 2.0 mm was produced in the same manner as in Example I, except that the material was rolled into a tape shape with a width of 3 rrm, and then this tape-like body was produced in the same manner as in Example I. A plate-shaped oxide superconductor was created.

The Jc and C-axis orientations of each of the oxide superconductors thus obtained were examined. The results are shown in Table 1.

In addition, J is liquid N, medium (77K) and liquid He (4.2
K) respectively O. Measurements were made by applying a magnetic field of 15T or 15T perpendicular to the longitudinal direction of the oxide superconductor and parallel to the wide surface. Further, the C-axis orientation was examined by X-ray diffraction.

As is clear from Table 1, the products produced by the method of the present invention had a high Jc value.

On the other hand, in Comparative Example 1, the direction perpendicular to the C-axis of the superconductor layer was not parallel to the direction of application of the magnetic field because the oxide superconductor was nine-wire, and in Comparative Example 2, l/d was Since the limit value of the present invention was exceeded, the angle between the perpendicular to the wide surface of the oxide superconductor and the C axis of the width direction portion of the superconductor layer did not fall within 15°C, and Comparative Example 3 In addition, 1/d was less than the limit value of the present invention, and the C-axis orientation of the oxide superconductor layer itself was insufficient, resulting in a low Jc value in all cases.

Example 5 Using the oxide superconductor produced in Example 1, J,
The effect of the applied direction of the magnetic field on the magnetic field was investigated.

The direction in which the magnetic field is applied is to place the oxide superconductor so that its wide side faces up and down, and to apply the magnetic field in the right lateral direction (0°) of the conductor.
, passing through the vertical direction (90') of the wide surface in the left horizontal direction (
180") in steps of 5 to 30 degrees. J was measured at 4.2 K with a magnetic field of 1T applied. The results are shown in Table 2.

As is clear from Table 2, J, has an angle of 0° or 18
The closer the angle is to 0°, that is, the more parallel the direction of the applied magnetic field is to the wide surface of the oxide superconductor, the higher the value is, and when the angle exceeds 15'' or is less than 165°, the value of Je decreases dramatically. This is because the direction perpendicular to the C axis, in which the fact of the oxide superconductor layer has a high value, is arranged parallel to the wide surface of the oxide superconductor. This means that it is necessary to make the angle between the C axis of the layer and the perpendicular to the wide surface of the oxide superconductor 151 or less in order to obtain a high Jc.

Example 6 The 0.09as' plate material obtained by rolling the material in Example 2 was made of alumina fiber as an insulating material and 0.09-1 as a reinforcing material.
This laminated body was wound around an SUS cylinder coated with Altanina and had an outer diameter of 30 mm to form a pancake with an outer diameter of 65 mm.
Next, this pancake was heat-treated under the same conditions as in Example 2, and then the pancake was impregnated with an epoxy resin and solidified to form an oxide superconducting coil.

Comparative Example 4 An oxide superconducting coil was manufactured in the same manner as in Example 5, except that a wire of 0.5 mm diameter obtained by drawing the material in Comparative Example 1 was used instead of the plate material. did. The Sli (8 mg+) and the number of winding layers in row 1 were the same as in Example 5.

The generated magnetic field was measured for each oxide superconducting coil obtained in this way. The generated magnetic field is applied to each coil in 4.2 K liquid He or 7
Measurements were made by placing them at the center of a 5.5T or 0.09T superconducting solenoid coil in liquid N2 at 7K. The results are shown in Table 3. Third table: Magnetic field strength excluding external magnetic field.

As is clear from Table 3, the product of the present invention (Example 6) had a large amount of current flow, and as a result, the generated magnetic field had a high value. On the other hand, in the comparative product (Comparative Example 4), since the coil conductor was made of nine wires, the direction perpendicular to the C axis of the superconductor layer was not parallel to the direction of the generated magnetic field, resulting in a low value of the generated magnetic field. [Effects] As described above, in the superconductor of the present invention, the superconductor layer is made of a two-dimensional superconductor, and the superconductor layer has a surface perpendicular to the C-axis with a high critical magnetic field that is energized by the superconductor. Since it is arranged parallel to the direction, Jc has a high value,
Therefore, a coil formed using this conductor can generate a high magnetic field.

Further, the above-mentioned superconductor can be efficiently manufactured by applying a normal drawing method, and has a remarkable industrial effect.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an embodiment of the superconductor of the present invention, Figure 2 is a sectional view showing an embodiment of the superconductor of the present invention;
The figure is a sectional view showing an example of a laminate used in manufacturing the superconductor of the present invention. DESCRIPTION OF SYMBOLS 1... Metal matrix, 2... Oxide superconductor layer, 3.5, 6.7... Metal material, 4... Superconducting substance. 4 Figure 1

Claims (3)

[Claims] (1) A tape-shaped superconductor with a rectangular cross section in which a superconductor layer is embedded in a metal matrix, wherein the width direction of the cross section of the superconductor layer is parallel to the wide surface of the tape-shaped superconductor. and the ratio l/d of the width direction length l parallel to the wide surface of the tape-shaped superconductor of the superconductor layer to the thickness d of the superconductor layer is in the range of 10 to 10^4, The superconductor layer is made of a two-dimensional superconductor whose critical magnetic field is larger in the direction perpendicular to the C-axis than in the direction parallel to the C-axis,
A superconductor characterized in that the angle between the perpendicular to the wide surface of the tape-shaped superconductor and the C axis of the widthwise portion of the superconductor layer is 15° or less. (2) Superconducting substances and metal materials of superconductors or their precursors are alternately laminated, this laminate is stretched into a tape-shaped wire with a rectangular cross section, and then this tape-shaped wire is subjected to heat treatment. Characteristic method for producing superconducting conductors. (3) A superconducting coil characterized in that the superconductor according to claim 1 is wound so that its wide surface is parallel to the direction of the generated magnetic field.