JPS63279514A - Superconductor wire rod, its manufacture and superconductive coil - Google Patents

Abstract

PURPOSE:To obtain a superconductor wire rod with large current density by filling the perovskite type oxide superconductor powder into a flat metal tube, with C faces of crystals oriented in parallel with the flat face of the metal tube. CONSTITUTION:The perovskite type oxide superconductor powder with the diameter/thickness ratio of 3-5 is filled into a metal tube with a circular cross section, and this metal tube is roll-machined until its width/thickness ratio is made to at least 2/1. The perovskite type oxide superconductor powder is filled so that C faces of crystals are oriented in parallel with the flat face of the metal tube, and a superconductor wire rod is wound so that the flat face is made parallel with the magnetic flux generated by the superconductor wire rod when it is excited. Since the C faces of crystals are oriented along the flat face of the superconductor wire rod, the superconductive current is liable to flow in the face direction of the superconductor wire rod, the critical current density of the superconductor wire rod in this direction is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Industrial Application Field) The present invention relates to a superconductor wire using perovskite-type oxide superconductor powder, a method for manufacturing the same, and a superconducting coil.

(Prior Art) In recent years, it has been announced that layered perovskite-type oxides based on Ba-La-Cu-0 may have a high critical temperature, and since then, research on oxide superconductors has been carried out in various places. Tiru (Z, Phys, B Condensed Mat
ter 64°189-193 (1986)). Among them, defective perovskite type (ABa2Cu3O7-5 type) with oxygen defects represented by Y-Ba-Cu-0 system.
(A is Y, Yb, Ha, fly, Eu.

The oxide superconductor of elements selected from Er, D+a and Lu) has a critical temperature of ■. It is attracting attention as a very promising material because it shows a high temperature of 90 or higher, which is higher than liquid nitrogen (Phys, Rev. Lett, vol. 58 N
o, 9, 908-910).

However, since this superconductor is a crystalline oxide and is obtained as a sintered body or powder, it is difficult to process it into a long object. Therefore, simply increasing the length of the superconductor powder causes the crystals to be arranged in random directions, making it impossible to obtain the desired critical current density.

Furthermore, in this superconductor, the value of the critical magnetic field in the magnetic field perpendicular to the zero plane of the crystal is significantly smaller than the value of the critical magnetic field in the magnetic field parallel to this, so the length of the superconductor increases while the orientation of the crystal remains random. However, when a superconducting coil is formed using a superconducting coil, there is a problem in that it is not possible to generate the originally large magnetic field.

(Problems to be Solved by the Invention) In this way, the Be.1 Busuite type superconductor is a sintered powder, and since superconducting current flows along the zero plane of the crystal, it is possible to It was difficult to obtain the desired critical current density.

In addition, in this superconductor, the value of the critical magnetic field in the magnetic field perpendicular to the zero plane of the crystal is significantly smaller than the value of the critical magnetic field in the magnetic field parallel to this, so the length of the crystal grows while the orientation direction of the crystal is random. However, when a superconducting coil is formed using a superconducting coil, there is a problem in that it is not possible to generate the originally large magnetic field.

The present invention was made to solve these conventional difficulties, and an object of the present invention is to provide a superconductor wire with a high current density using perovskite superconductor powder, a method for manufacturing the same, and a superconducting coil.

[Structure of the Invention] (Means for Solving the Problems) That is, the superconductor wire of the present invention has 1,
It is characterized by being filled with perovskite-type oxide superconductor powder with the 0-plane of the crystal oriented in the length direction of the metal tube, and the manufacturing method is such that the diameter-to-thickness ratio is 3 to 3. The perovskite-type oxide superconductor powder of No. 5 is filled into a metal tube having a circular cross section, and the metal tube is rolled so that the width to thickness ratio is at least 2/1, and The superconducting coil of the present invention includes a superconducting wire formed by filling a flat metal tube with perovskite-type oxide superconductor powder with the 0-plane of the crystal oriented parallel to the flat surface of the metal tube. The superconductor wire is characterized in that the flat plane is wound so as to be parallel to the magnetic flux generated by energizing the superconductor wire.

The oxide superconductor containing a rare earth element and having a perovskite structure needs only to be able to realize a Hi conduction state, and is based on the ^Ba2Cu3O7-δ system (δ represents an oxygen defect and is usually 1 or less, and ^ is Y, Wb, Ho). , Dy, Eu
.

Defect perovskite type with oxygen defects such as [r, Tm, Lu; part of Ba can be replaced with sr etc.), 5
The oxide is an oxide having a perovskite structure in a broad sense, such as a layered berovskite type such as r-La-CU-0 type. Rare earth elements are also broadly defined to include SC, Y, and lanthanum elements. A typical system is Y-Ba-Cu-
In addition to 0 series, 5c-Ba-Cu-0 series, 5r-La-
Examples include Cu-0 type, and systems in which Sr is replaced with Ba and Ca.

The oxide superconductor of the present invention can be obtained, for example, by the manufacturing method shown below. Y, Ba, Cu and O
Constituent elements of the Busuyrite type oxide superconductor are thoroughly combined. In this case, each raw material is Y2O3゜Bad, CuO
Oxides such as the following can be used. In addition to these oxides, carbonates, nitrates, and
Compounds such as oxalates and hydroxides may also be used. The elements constituting the perovskite-type oxide superconductor are basically mixed so as to have a stoichiometric composition, but there may be a slight deviation depending on the manufacturing conditions and the like. For example, Y
-Ba-Cu-0 system: 2m of Ba per 1mol of V
ol, Cu 3m.

1 is the standard composition, but in practice YO16~1.4m0
1%, Ba 1.5-3. Omo1%, cu2.0~
A deviation of about 4.0101% is not a problem.

Previous) Wood raw materials are mixed, calcined, crushed, reconstituted into the desired shape, and fired. Calcining is not necessarily necessary. The firing/calcination is preferably carried out at about 800 to 940''C in an oxygen-containing atmosphere where sufficient oxygen can be supplied.

Also, the ratio of the diameter in the surface direction to the thickness in the C-axis direction is 3 to 5.
The diameter (long axis of C) is suitably about 1 to 5 μm.

The metal tube used for the superconductor wire of the present invention is AOv
In particular, metal tubes such as Ag and Pd do not oxidize even at high temperatures, so by annealing them in oxygen or an oxygen-containing atmosphere after flattening, the above-mentioned perovskite-type superconducting tubes can be made. The value of δ can be reduced by introducing oxygen into the oxygen vacancies in the body powder.

Further, the perovskite-type oxide superconductor powder in the present invention does not need to be 100% oriented, and it is effective if the orientation rate is at least about 10%.

In addition, the orientation rate in the present invention is determined by removing the coating metal of the obtained wire, measuring the diffraction intensity of the internal oxide superconductor using X-ray diffraction, and from the change in the diffraction intensity from the zero plane. It is.

To manufacture the superconductor wire of the present invention, first, BaCO3
, Y20, , CuO, and other perovskite-type oxide superconductor raw materials are mixed in a stoichiometric composition with respect to the above-mentioned general formula, pulverized, and dried. It is baked at a temperature of ~1000°C for several hours to three days to react and crystallize.

Next, this fired product is pulverized using a ball mill, a ball mill, a sand grinder, or other known means. At this time, the perovskite-type oxide superconductor powder is divided from the cleavage plane and becomes fine powder. The pulverization is carried out until the average particle diameter (maximum axial length for C improvement) is approximately 1 to 5 μm and the diameter to thickness ratio is 3 to 5. If necessary, divide the pulverized powder into portions within the above range.
C may be used.

Thereafter, this perovskite-type oxide superconductor powder was placed in a metal tube made of Nb, Ag, Pd, Cu, stainless steel, etc., with an outer diameter of about 20 mm and an inner diameter of about 15 mm, and was pressurized using a press, swaging machine, etc. Rolling is performed until the width-to-thickness ratio is 271 or more and the filling rate is 60% or more.

In this rolling process, the superconductor powder is oriented to an orientation rate of 70% or more.

Furthermore, in the case of manufacturing a long superconductor, the following method can be adopted, for example.

■ After compacting the metal tube filled with superconductor powder using a swaging machine, etc., it is passed through multiple sets of roller dies or regular dies so that it is deformed into an elliptical shape with a large major axis to minor axis ratio. and the short axis is 1710 or less,
Preferably, the surface is reduced to 1/20, and finally it is formed flat using a cylindrical row.

■ After compacting the metal tube filled with superconductor powder using a swaging machine, etc., it is cold drawn and has an outer diameter of 1.
The surface is reduced to 710 or less, preferably 1720 or less, and finally it is flattened using a cylindrical roller.

In addition, in these methods, annealing may be performed in the middle as necessary.

After forming the wire to the final wire diameter in this manner, it is annealed at 800 to 940° C. for about one day in an air or oxygen-containing atmosphere. This annealing in air or oxygen-containing atmosphere results in
Oxygen is introduced into the oxygen vacancies in the perovskite superconductor, reducing the value of δ and further improving the current density of the superconductor wire.

Of the two methods described above, in method (2), since the carbon of the superconductor powder starts to be oriented in the direction of the flat surface from a relatively low filling rate, a higher orientation rate can be obtained.

The flat superconductor wire produced in this way is made of perovskite-type oxide superconductor powder during the wire drawing process.
Since the planes are also oriented in the longitudinal direction of the wire, the critical current capacity of the wire as a whole is greatly improved.

The superconductor wire of the present invention may be used as it is by being formed into a coil, but a large number of them may be arranged in a tube made of a stabilizing material, and then subjected to swaging processing, cold drawing processing, etc. It is also possible to form the crystal into a flat shape in which the crystal C is parallel to the flat surface and use it as a multi-wire material.

In order to form this superconductor wire into a coil, it is sufficient to form the superconductor wire into an arbitrary coil shape so that the oblique plane is parallel to the magnetic flux generated by energizing the superconductor wire H.

(Function) In the superconductor wire of the present invention, since the C of the crystal in which the superconducting current flows in the perovskite-type oxide superconductor powder filled in the metal tube is oriented along the flat surface of the superconductor wire. , the superconducting current flows more easily in the plane direction of the superconductor wire, and the critical current density of the superconductor wire in this direction is improved.

Furthermore, in the method for manufacturing a superconductor wire of the present invention, during rolling of a metal tube, perovskite superconductor powder having a diameter-to-thickness ratio of 3 to 5 is oriented so that its zero plane is parallel to the rolling direction. , therefore, just by considering its diameter-to-length ratio and the degree of rolling of the instep, the forming and E'i1
Orientation of superconductor powder can sometimes be performed.

Furthermore, in the superconducting coil of the present invention, the zero plane of the oxide superconductor crystal is oriented in the direction of the magnetic field produced by itself, so the critical magnetic field is improved, and the electromagnetic force is perpendicular to the flat plane of the superconductor wire. comes into play.

(Example) Next, examples of the present invention will be described.

Example BaC03 powder 2Illo1%, Y2O3 powder 0. sm
1% of CuO powder and 3 mo1% of CuO powder were mixed thoroughly and fired at 900°C in the air for 48 hours to cause a reaction.This powder raw material was then fired in oxygen at 800°C for 24 hours to cause a reaction, thereby adding oxygen to the oxygen vacancies. After introduction, it was crushed using a ball mill and classified to obtain particles with an average particle size of 2 μm and a diameter-to-thickness ratio of 3 to 5.
Perovskite-type superconductor powder was obtained.

Next, the oxide superconductor powder was mixed with an outer diameter of 20 ml and an inner diameter of 15 ml.
One end of n1 length 100 mm is placed in a sealed Ag tube,
After sealing the other end, the cross section is made with a long diameter of 2'Wl using a roller die and a die in which the ratio of the major axis to the minor axis increases sequentially.
The area was cold-reduced until it became an elliptical shape with a short axis of 1 inch, and finally it was formed into a root shape with a thickness of 0.5 mm and a width of 3 nm using a cylindrical roll, and then heated at 900°C in oxygen for 12 hours. Time annealing was performed.

The superconductor wire obtained in this way was cut in the length direction and the flattening force of the wire and the orientation rate of the superconductor powder in the direction were measured, and the orientation rate was 70% in the width direction and 75% in the length direction. Met. Further, the filling rate of superconductor powder in the coating was 85%. Also, when we measured its superconducting properties, we found that its critical temperature was 87, and its critical current density was 77.
When measured under the condition of 0 field, it was 1000 A/-.

In addition, this superconductor wire was formed into a coil with an outer diameter of 3 Ou and a length of 50 nm so that the flat surface was parallel to the generated magnetic flux, and after annealing in oxygen at 900°C for 12 hours, the critical magnetic field was measured. It turned out to be 5■.

On the other hand, the critical temperature of the superconductor block obtained by compression molding the superconductor powder used in the example to have a porosity equal to the filling rate of the superconductor wire in the example and heat-treating it at 900°C for 12 hours was 93. , 77, its critical current density was measured to be 200 A/m. Furthermore, a superconductor coil having the same shape as that of the example was fabricated using the superconductor powder and AQ powder used in the example, and a superconductor wire with a circular cross section having the same cross-sectional area as that of the example, and its critical magnetic field When measured, it was 0.5■.

[Effects of the Invention 1] As is clear from the above examples, the superconductor wire of the present invention has a structure in which the zero face of the crystal through which the superelectric S current flows in the perovskite-type oxide superconductor powder filled in the metal tube. Since it is oriented along the flat surface of the superconductor wire, the superconducting current tends to flow in the plane direction of the superconductor wire, and a high critical current density in this direction can be obtained.

In addition, in the method for manufacturing a superconductor wire of the present invention, during rolling of a metal tube, the perovskite superconductor powder is oriented so that its zero plane is parallel to the rolling direction, and therefore the diameter to length ratio is simply By simply considering the degree of rolling in the rolling process, the superconductor powder can be oriented simultaneously with forming.

Further, in the superconducting coil of the present invention, since the zero plane of the oxide superconductor crystal is oriented along the direction of the magnetic field produced by itself, a high critical magnetic field can be obtained.

Claims (1)

[Claims] (1) A flat metal tube is filled with perovskite-type oxide superconductor powder with the C-plane of the crystal oriented parallel to the flat surface of the metal tube. superconductor wire material. (2) The superconductor wire according to claim 1, wherein the perovskite-type oxide superconductor powder has a diameter-to-thickness ratio of 3 to 5. (3) The superconductor wire according to claim 1 or 2, wherein the oxide superconductor powder is a perovskite-type oxide superconductor containing a rare earth element. (4) The oxide superconductor powder is ABa_2Cu_3
O_7_-_δ-based oxide superconductor (A is Y, Yb,
4. The superconductor wire according to claim 3, wherein the superconductor wire is an element selected from Ho, Dy, Eu, Er, Tm, and Lu. (5) The oxide superconductor powder is Y-Ba-Cu-O
5. The superconductor wire according to claim 4, which is a superconductor wire. (6) Claims 1 to 5, characterized in that the diameter of the oxide superconductor powder is 1 to 5 μm.
The superconductor wire according to any one of the above items. (7) The orientation rate of the oxide superconductor powder is at least 70
%, the superconductor wire according to any one of claims 1 to 6. (8) The filling rate of the oxide superconductor powder is at least 60
%, the superconductor wire according to any one of claims 1 to 7. (9) The width-to-thickness ratio of the flat metal tube is at least 2/1.
A superconductor wire according to any one of claims 1 to 8, characterized in that: (10) Filling a metal tube with a circular cross section with perovskite-type oxide superconductor powder having a diameter-to-thickness ratio of 3 to 5,
A method for manufacturing a superconductor wire, which comprises rolling the metal tube so that the width to thickness ratio is at least 2/1. (11) The method for manufacturing a superconductor wire according to claim 10, wherein rolling of the metal tube having a circular cross section is performed together with area reduction processing. (12) The method for producing a superconductor wire according to claim 10 or 11, wherein the oxide superconductor powder is a perovskite-type oxide superconductor containing a rare earth element. (13) The oxide superconductor powder is ABa_2Cu_
3O_7_-_δ-based oxide superconductor (A is Y, Yb
, Ho, Dy, Lu, Er, Tm, and Lu. ) The method for manufacturing a superconductor wire according to any one of claims 10 to 12. (14) The oxide superconductor powder is Y-Ba-Cu
The method for producing a superconductor wire according to any one of claims 10 to 13, characterized in that the superconductor wire is -O-based. (15) The diameter of the oxide superconductor powder is 1 to 5 μm
A method for manufacturing a superconductor wire according to any one of claims 10 to 14. (16) A superconductor wire obtained by filling a flat metal tube with perovskite-type oxide superconductor powder with the C-plane of the crystal oriented parallel to the flat surface of the metal tube. A superconducting coil characterized in that the superconducting wire is wound in parallel with the magnetic flux generated by energizing the superconducting wire. (17) The superconducting coil according to claim 16, wherein the perovskite-type oxide superconductor powder has a diameter-to-thickness ratio of 3 to 5. (18) The superconducting coil according to claim 16 or 17, wherein the oxide superconductor powder is a perovskite-type oxide superconductor containing a rare earth element. (19) The oxide superconductor powder is ABa_2Cu_
3O_7_-_δ-based oxide superconductor (A is Y, Yb
, Ho, Dy, Eu, Er, Tm, and Lu)
The superconducting coil according to any one of Items 6 to 18. (20) The oxide superconductor powder is Y-Ba-Cu-
The superconducting coil according to any one of claims 16 to 19, characterized in that it is O-based. (21) The diameter of the oxide superconductor powder is 1 to 5 μm
A superconducting coil according to any one of claims 16 to 20, characterized in that: (22) The orientation rate of the oxide superconductor powder is at least 7
22. The superconducting coil according to any one of claims 16 to 21, wherein the superconducting coil is 0%. (23) The filling rate of the oxide superconductor powder is at least 6
The superconducting coil according to any one of claims 16 to 22, wherein the superconducting coil is 0%. (24) The width-to-thickness ratio of the flat metal tube is at least 2/
1. The superconducting coil according to any one of claims 16 to 23, characterized in that: