JPH0534291B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a superconducting material.

[Prior art and its problems]

Superconducting materials are already used in high-energy particle accelerators,
In MRI-CT physical property research equipment for medical diagnosis, etc.
It has been put into practical use in the form of superconducting magnets. Applications include generators, energy storage and conversion, linear motor cars, magnetic separation devices for resource recovery, nuclear fusion reactors, power transmission cables, magnetic shielding materials, etc.
Furthermore, superconducting elements using the Josephson effect are expected to be applied to ultra-high-speed computers, infrared detectors, low-noise amplifiers, etc., and if these are put into full-scale practical use, they will have significant industrial and social impact. The magnitude of the impact is still difficult to measure.

A typical superconducting material developed so far is Nb-Ti alloy, which is currently 9T
It is widely used as a wire for generating magnetic fields. The Tc (critical temperature at which a superconducting state exists) of the Nb-Ti alloy is 9K. In addition, compound-based superconducting materials have been developed as materials with Tc much higher than Nb-Ti alloys, and currently Nb ₃ Sn (Tc: 18K) V ₃
Ga (Te: 15K) has been made into wire and put into practical use. Furthermore, a Tc of 23K has been obtained with Nb ₃ Ge.

As described above, efforts have been made for many years to obtain high Tc superconducting materials, but Tc 23K has become a major barrier in conventional alloy-based and compound-based superconducting materials. Cooling superconducting materials with Tc below 23 K requires expensive liquid helium, which hinders their widespread application. As a material to break down this Tc wall,
In 1986, Mr. Mu¨ller of IBM Zurich et al.
Since the announcement that signs of superconductivity were observed in -La-Cu-O-based oxides, the race to develop oxide-based superconducting materials has accelerated. In 1986, the Tc was 40K, but in early 1987, Y-Ba-Cu-O superconducting materials were developed that exceeded the liquid nitrogen temperature of 77K, and the Tc reached approximately 93K. moreover,
Since then, vigorous development has continued, and the development of superconducting materials that exhibit superconductivity at room temperature has been reported, although there are currently safety issues. The discovery of high-temperature superconducting materials that can be used at liquid nitrogen temperatures has raised expectations for the aforementioned application fields, and superconducting materials with high Jc (critical current density) values can be easily manufactured. No method has yet been proposed.

Therefore, an object of the present invention is to provide a method by which a superconducting material having a high Jc value can be easily produced.

[Means for solving problems]

This invention involves thermally spraying particles made of a composite oxide superconducting material containing Cu _x O _y groups onto the surface of a base material.
A superconducting film is formed on the surface, and a rolling force is applied to the thus obtained superconducting material while heating it, and in this way, among the crystal planes of the particles of the superconducting film, the crystal planes having excellent electrical conductivity are , is characterized in that it is aligned parallel to the surface of the superconducting film.

Next, a method for manufacturing a superconducting material according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of a plasma spraying apparatus for forming a superconducting film on the surface of a base material, and FIG.
FIG. 1 is a front view showing one embodiment of the method of the present invention.

This invention first involves spraying onto the surface of a base material 1 made of Cu or the like using a plasma spraying apparatus shown in FIG.
A powder made of a composite oxide superconducting material containing Cu _x O _y groups is thermally sprayed. The plasma spraying equipment is a vacuum vessel 2
and a thermal spray nozzle 3 provided in the vacuum container 2,
It consists of an electrode 4 provided within the thermal spray nozzle 3 and a power source 5 connected between the thermal spray nozzle 3 and the electrode 4.

The base material 1 is installed in a vacuum vessel 2 facing the thermal spray nozzle 3, the pressure inside the vacuum vessel 2 is reduced, and a working gas such as argon or helium is supplied into the rear end of the thermal spray nozzle 3. Inside the tip, Cu _x O _y
A powder made of a composite oxide superconducting material containing a group of 100% is supplied, and a power source 5 is activated to generate a plasma arc between the thermal spray nozzle 3 and the electrode 4. As a result, a superconducting film 6 made of a composite oxide superconducting material containing Cu _x O _y groups is formed on the surface of the base material 1 .

Next, in this way, the base material 1 and the superconducting film 6
Once the superconducting material 7 is obtained, as shown in FIG. 2, a rolling force is applied to the superconducting material 7 by a rolling roll 8 while heating the superconducting material 7. As a result, the superconducting film 6, which was randomly convoluted before applying the rolling force, that is, in the as-sprayed state,
The specific crystal planes of the particles are aligned parallel to the superconducting film 6. That is, as shown in FIG. 3, the ab crystal plane, which has much better electrical conductivity than other planes, is aligned parallel to the plane of the superconducting film 6. This is said to have imparted orientation to the particles. As a result, the value of Jc of the superconducting film 7 increases.

〔Example〕

Next, embodiments of the invention will be described.

Using the plasma spraying equipment shown in Figure 1, Ni
Base material 1 made of base alloy (thickness 1.0 mm, length 20 mm, width
30 mm), a superconducting film 6 made of Y _0.3 Ba _0.7 Cu ₁ O _3-y and having a thickness of 150 μm was formed. That is, the first
In the vacuum vessel 2 of the plasma spraying apparatus shown in the figure,
A plate-shaped substrate 1 made of Cu is installed, and a mixed gas of argon gas and helium gas (Ar:
20/min, He: 40/min) into the rear end of the thermal spray nozzle 3, and 25 KW of power is supplied from the plasma power source 5 between the thermal spray nozzle 3 and the electrode 4 to In the front end, from grain size 10
Particles of superconducting material consisting of Y _0.3 Ba _0.7 Cu ₁ O _3-y with a diameter of 100 μm are supplied, and the atmospheric pressure inside the vacuum vessel 2 is set to 80 μm.
Apply a reduced pressure to millibar and deposit a thickness on the surface of substrate 1.
A superconducting film 6 of 150 μm was formed.

While heating the superconducting material 7 obtained in this way to 800°C, as shown in FIG.
The superconducting material 7 was compressed by the following steps until the thickness of the superconducting film 7 became 75 μm. Next, the superconducting material 7 was heated to a temperature of 930° C. for 30 minutes.

The superconducting material thus produced was subjected to X-ray diffraction to examine the orientation of particles in the superconducting film. As a result, the peak of the crystal plane 003 of the particles of the superconducting film is different from that of other crystal planes 001,
The peaks of these crystal planes were much higher than those of 002, 004, and 005, whereas in the superconducting material produced by the method of the present invention, the peaks of these crystal planes were almost the same. This means that particle orientation has occurred in the superconducting film, that is, the a-b crystal planes of the particles of the superconducting film, which have excellent electrical conductivity, are aligned parallel to the plane of the superconducting material.

Next, the Tc and Jc of the superconducting material produced by the method of this invention were investigated. As a result, the value of Jc of the superconducting material of the present invention was 8000 A/cm ² , whereas the value of Jc of the comparative superconducting material, which did not apply any reduction to the superconducting material, was 150 A/cm ² . value is,
Both were 90.5K.

〔Effect of the invention〕

As explained above, according to the present invention, by applying pressure to the superconducting film, the direction of the ab crystal plane of the particles of the superconducting film, which has excellent electrical conductivity, can be changed.
Since it is aligned parallel to the surface of the superconducting film, the value of Jc increases significantly.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a plasma spraying apparatus, FIG. 2 is a front view showing an embodiment of the method of the present invention,
FIG. 3 is an explanatory diagram showing crystal planes of particles of a superconducting film. In the drawings, 1... Base material, 2... Vacuum container, 3... Thermal spray nozzle, 4... Electrode, 5... Power source, 6... Superconducting film, 7... Superconducting material, 8... Rolling down roll.

Claims (1)

[Claims] 1. On the surface of a base material, a powder made of a composite oxide superconducting material containing a Cu _x O _y group is thermally sprayed to form a superconducting film on the surface, and the superconducting material thus obtained is heated. A method for producing a superconducting material, which comprises applying a rolling force to the superconducting material, thereby aligning crystal planes with excellent electrical conductivity among the crystal planes of the particles of the superconducting film parallel to the plane of the superconducting film.