JPH0534289B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing a superconducting material in which a film made of a superconducting substance is formed on the surface of a base material. [Prior Art] Superconducting materials have already been put to practical use in the form of superconducting magnets in high-energy particle accelerators, MRI-CT for medical diagnosis, and physical property research equipment. Such superconducting materials have a wide range of applications, such as power generators, energy storage and conversion,
Linear motor cars, magnetic separation equipment for resource recovery,
Applications of superconducting materials to nuclear fusion reactors, power transmission cables, magnetic shielding materials, etc. are expected, and superconducting materials using the Josephson effect are also expected to be used in ultra-high-speed computers, infrared detectors, and low-noise amplifiers and mixers. Applications of the device are expected. The magnitude of the industrial and social impact when these are fully put into practical use is immeasurable. A typical superconducting material developed so far is Nb-Ti alloy, which is currently widely used as a wire for generating magnetic fields up to 9T.
The Tc (critical temperature at which a superconducting state exists) of the Nb-Ti alloy is 9K. Compound-based superconducting materials have been developed as superconducting materials with Tc much higher than this Nb-Ti alloy, and currently Nb ₃ Sn (Tc: 18K) and V ₃ Ga
(Tc: 15K) has been made into wire rod and is in practical use. Furthermore, according to Nb ₃ Ge, a Tc of 23K has been obtained. As described above, efforts have been made for many years to obtain high Tc superconducting materials, but Tc23K is currently a major barrier to conventional alloy-based and compound-based superconducting materials. That is, Tc
Cooling superconducting materials below 23K requires expensive liquid helium, which hinders their widespread application. Regarding superconducting materials that can significantly break down this Tc barrier, in 1986 Muller of the IBM Zurich Research Institute
Since they announced that signs of superconductivity were observed in Ba-La-Cu-O-based composite oxides, the race to develop composite oxide superconducting materials has accelerated.
In other words, in 1986, the Tc of superconducting materials was 40K, but at the beginning of the following year (1987), Y-
A complex oxide superconducting material containing Ba-Cu-O based Cu _x O _y groups has been developed, and its Tc has reached approximately 93K. Furthermore, the development of superconducting materials has continued vigorously since then, and recently, the development of superconducting materials that exhibit superconducting phenomena at room temperature has been reported, although there are problems with safety and the like. As mentioned above, with the development of a composite oxide superconducting material containing Cu _x O _y groups that can be used at liquid nitrogen temperature (77K), there are expectations for the practical application of superconducting materials in the above-mentioned application fields. The level has been raised further. In order to put superconducting materials into practical use, what is necessary is the development of processing techniques such as forming superconducting materials into wires and films. Among these processing techniques, methods of forming a composite oxide superconducting film on the surface of a base material using sputtering method and electron beam evaporation method have been attempted, and recently Formation of coatings by laser vapor deposition or plasma spraying has been investigated. [Problems to be Solved by the Invention] However, when a film of a composite oxide superconducting material containing Cu _x O _y groups is formed on the surface of a base material by laser vapor deposition or plasma spraying, laser As-deposited or plasma-sprayed,
There is a problem in that the amount of oxygen in the film components is insufficient, making it impossible to form a film having desired superconducting properties. Therefore, a film of a composite oxide superconducting material containing Cu _x O _y groups is formed on the surface of the base material by laser evaporation method or plasma spraying method, and the resulting laser evaporated as-deposited film or plasma The as-sprayed superconducting material is heated to a predetermined temperature in an oxygen-containing atmosphere, held at that temperature for a predetermined time, and then cooled at a predetermined rate. Attempts have been made to impart superconducting properties to these materials. However, the above-mentioned heating and
In order to perform heat treatment consisting of holding and cooling, it takes a long time and requires large-scale equipment, which poses a problem of poor processing efficiency. Therefore, the object of the present invention is to
When producing a superconducting material in which a film of a composite oxide superconducting material containing Cu _x O _y groups is formed, the oxygen deficient in the film components is efficiently replenished, and thus the film has excellent superconducting properties. An object of the present invention is to provide a method for manufacturing a superconducting material. [Means for solving the problem] This invention forms a film of a composite oxide superconducting material containing Cu _x O _y groups on the surface of a base material, and then
The film is characterized in that by spraying excited oxygen gas toward the film of the superconducting material obtained in this way, oxygen is supplied to the film components, thus imparting excellent superconducting properties to the film. It is something. The superconducting material in this invention, for example,
It is prepared using a laser vapor deposition apparatus as shown in the figure or a plasma spray apparatus as shown in FIG. The laser evaporation apparatus shown in FIG.
, a vapor deposition source 5 provided in a vacuum container 4, and a laser generator (not shown) for emitting a laser a toward the vapor deposition source 5. 6 is a heater for heating the base material 2; Cu _x as vapor deposition source 5
A composite oxide sintered body containing an O _y group is used, and a base material 2 is placed above a vapor deposition source 5 . Next, the pressure inside the vacuum container 4 is reduced to a predetermined degree of vacuum, and the laser a
is irradiated onto the vapor deposition source 5 to cause particles evaporated from the vapor deposition source 5 to adhere to the surface of the base material 2 heated by the heater 6 . Thus, Cu _x on the surface of the base material 2
A superconducting material 1 on which a film 3 of a composite oxide superconducting material containing an O _y group is formed is prepared. The plasma spraying apparatus shown in FIG.
and a thermal spray nozzle 7 provided in the vacuum vessel 4,
Tungsten electrode 8 provided on thermal spray nozzle 7
and a power source 9 connected between the thermal spray nozzle 7 and the tungsten electrode 8. Vacuum container 4
The base material 2 is disposed inside facing the thermal spray nozzle 7.
Next, the pressure inside the vacuum container 4 is reduced to a predetermined degree of vacuum,
A working gas such as argon or helium and powder of a composite oxide superconducting material containing a Cu _x O _y group are supplied into the thermal spray nozzle 7 , and the power source 9 is activated to cause the thermal spray nozzle 7 to reach the tungsten electrode 8 . Generates a plasma jet towards the enemy. In this way, a superconducting material 1 is prepared in which a film 3 of a composite oxide superconducting material containing Cu _x O _y groups is formed on the surface of the base material 2 . Next, the superconducting material 1 prepared as described above is placed in a container 10 in an oxygen-containing atmosphere as shown in FIG.
to be contained within. The container 10 is provided with an injector 11 for spraying excited oxygen gas toward the coating 3 of the superconducting material 1. The injector 11 includes a stainless steel conduit 13 with an oxygen supply tube 12 attached to its base end, and a quartz excitation tube 15 continuous with the conduit 13 and around which a high-frequency coil 14 is wound.
It is made up of. Oxygen blown into the injector 11 through the oxygen supply pipe 12 is excited by the high frequency coil 14 in the excitation pipe 15 and then
is sprayed towards. In this way, the oxygen emitted from the injector 11 penetrates into the coating 3 of the superconducting material 1, and as a result,
Oxygen lacking in the components of the film 3 is replenished, and a superconducting material is manufactured in which a film 3 of a composite oxide superconducting material containing Cu _x O _y groups with excellent superconducting properties is formed on the surface of the base material 2. . When the superconducting material 1 has a certain area or more, oxygen gas is injected while moving the injector 11 toward the coating 3. By doing so, oxygen is uniformly supplied over the entire surface of the coating 3 of the superconducting material 1. Next, examples of the present invention will be explained. [Example] As a composite oxide sintered body as a vapor deposition source, Y _1.2
Diameter 20mm, thickness with a composition of Ba _0.6 CuO _x
A 10 mm disc-shaped composite oxide sintered body was used, and a rectangular shape made of yttrium-stabilized zirconia (YSZ) with a side length of 15 mm and a thickness of 1 mm was used as the base material for the evaporation target. Using a plate, a film of superconducting material was formed on the surface of the base material using the laser vapor deposition apparatus shown in FIG. 2 under the following conditions. (a) Vacuum degree of vacuum container: 10 ^-2 Torr (oxygen atmosphere) (b) Heating temperature of base material: 700℃ (c) Type of laser beam: Carbon dioxide laser (d) Laser beam output: 300W (e) Laser beam irradiation time: 5 minutes In this way, a superconducting material was prepared in which a 2 μm thick film having a composition of Y _0.3 Ba _0.6 Cu ₁ O _x was formed on the surface of the base material. Next, excited oxygen gas was blown onto this superconducting material using the apparatus shown in FIG. 1 under the following conditions to replenish oxygen into the film components, thereby producing a superconducting material of the present invention. (a) Atmosphere inside the container: O ₂ : 80%, Ar: 20% (b) Pressure inside the container: atmospheric pressure (c) Flow rate of oxygen gas from the injector: 5/min (d) High frequency of the excitation tube Coil output: 2kw The Tc (superconducting critical temperature) and
Jc (critical current density) at 77K was investigated by four-terminal resistance measurement method. The results are shown in Table 1.

〔Effect of the invention〕

As described above, according to the present invention, when producing a superconducting material in which a film of a composite oxide superconducting material containing Cu _x O _y groups is formed on the surface of a base material, there is Oxygen is efficiently replenished in a low-temperature state without cracking or melting the film, thus producing an industrially useful effect that allows the production of a superconducting material having a film with excellent superconducting properties.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of supplying oxygen to the film components of a superconducting material by the method of the present invention, and FIG. FIG. 3 is a schematic sectional view showing a laser vapor deposition apparatus, and FIG. 3 is a schematic sectional view showing a plasma spraying apparatus for producing a superconducting material. In the drawings, 1... superconducting material, 2... base material, 3... film,
4... Vacuum container, 5... Evaporation source, 6... Heater,
7... Thermal spray nozzle, 8... Tungsten electrode, 9
...Power source, 10...Container, 11...Injector, 12
... Oxygen supply pipe, 13 ... Conduit, 14 ... High frequency coil, 15 ... Excitation tube.

Claims (1)

[Claims] 1 Forming a film of a composite oxide superconducting material containing Cu _x O _y groups on the surface of the base material, and then spraying excited oxygen gas toward the film of the superconducting material thus obtained. A method for producing a superconducting material, characterized in that oxygen is replenished into the coating components, thereby imparting excellent superconducting properties to the coating.