JP2012003983A - Manufacturing method of oxide superconducting thin film wire rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a long oxide superconducting thin film wire rod with steady superconducting characteristics by an MOD method capable of forming an oxide superconducting thin film with uniform characteristics from one end to the other end.SOLUTION: A manufacturing method of an oxide superconducting thin film wire rod by forming an oxide superconducting thin film by a coating thermal decomposition method with an atmosphere furnace using a metal organic compound as a raw material comprises: a coating film making step in which a coating film is made by coating on an oriented metallic substrate with the solution of the metal organic compound; a calcination heat treatment step in which a calcined film is made by thermal decomposition and removal of an organic constituent contained in the metal organic compound of the coating film; and a sintering heat treatment step in which the oxide superconducting thin film is made by crystallization of the calcined film. In the calcination heat treatment step, heating is applied in the atmosphere furnace in which an oxidation catalyst is disposed at an exhaust port.

Description

  The present invention relates to a method for manufacturing an oxide superconducting thin film wire, and more particularly to a method for manufacturing an oxide superconducting thin film wire focusing on a calcining heat treatment method in a coating pyrolysis method.

  Since the discovery of high-temperature superconductors that have superconductivity at the temperature of liquid nitrogen, development of high-temperature superconducting wires aimed at application to power devices such as cables, current limiters, and magnets has been actively conducted. Among them, an oxide superconducting thin film wire obtained by thinning an oxide superconductor has attracted attention.

One method for producing an oxide superconducting thin film wire is a coating pyrolysis method (Metal Organic Deposition, abbreviated as MOD method) (Patent Document 1). In this method, a metal organic compound solution is applied to a substrate to prepare a coating film (coating film manufacturing process), and then the metal organic compound is heat-treated (calcined) at, for example, around 500 ° C. to remove the organic component of the metal organic compound. Crystallization is achieved by thermally decomposing (calcination heat treatment step) and heat-treating (main firing) the obtained pyrolyzate (MOD calcined film) at a higher temperature (for example, around 800 ° C.) (main heat treatment step). To produce an oxide superconducting thin film made of an oxide superconductor represented by, for example, REBa ₂ Cu ₃ O _7-X (RE: rare earth element), and is a vapor phase method mainly produced in vacuum Compared with (evaporation method, sputtering method, pulsed laser deposition method, etc.), the manufacturing facility is simple, and it is easy to cope with a large area and a complicated shape.

JP 2007-165153 A

  However, when a long oxide superconducting thin film wire is manufactured using the conventional MOD method, an oxide superconducting thin film having uniform characteristics from the beginning to the end of the oxide superconducting thin film wire is not formed, and the superconducting characteristics vary. It may have occurred and was a problem.

  Therefore, the present invention is capable of forming an oxide superconducting thin film having uniform characteristics from the start to the end in the production of a long oxide superconducting thin film wire using the MOD method. It is an object of the present invention to provide a method for producing an oxide superconducting thin film wire capable of producing an oxide superconducting thin film wire having the following.

  As a result of intensive studies, the present inventor has found that the above-mentioned problems can be solved by the inventions of the following claims, and has completed the present invention. Hereinafter, the invention of each claim will be described.

The invention described in claim 1
Using a metal organic compound as a raw material, an oxide superconducting thin film wire is produced by forming an oxide superconducting thin film by a coating pyrolysis method using an atmospheric furnace, and a method for producing an oxide superconducting thin film wire,
A coating film production step of producing a coating film by applying a solution of the metal organic compound on an oriented metal substrate;
A calcining heat treatment step for producing a calcined film by thermally decomposing and removing an organic component contained in the metal organic compound of the coating film;
A calcination heat treatment step of crystallizing the calcined film to produce an oxide superconducting thin film,
The method for producing an oxide superconducting thin film wire, wherein the calcining heat treatment step is a heat treatment step of heating in an atmosphere furnace in which an oxidation catalyst is disposed at an exhaust port.

  The present inventor has conducted various experiments and studies on the cause of variation in superconducting characteristics in a long oxide superconducting thin film wire. As a result, it has been found that the conventional MOD method has a problem in the calcination heat treatment step.

This will be described with reference to FIG. FIG. 2 is a diagram showing an outline of a calcination heat treatment step in the conventional MOD method. As shown in FIG. 2, a long oriented metal substrate 1 having a coating film of a raw material solution formed on the surface thereof is inserted in an atmosphere furnace 2 (electric furnace) in the longitudinal direction as indicated by an arrow 10, Transported at speed. Since the atmosphere furnace 2 is heated to a calcining heat treatment temperature (about 500 ° C.) in an atmosphere of a mixed gas 4 of nitrogen and oxygen introduced from the gas inlet 8, the solvent and the metal organic compound in the coating film The organic component contained in is volatilized and thermally decomposed in the furnace and desorbed from the coating film. The desorbed solvent and organic components are decomposed into gas (water H ₂ O and carbon dioxide CO ₂ ) by heat and sent to the exhaust port 3 as indicated by an arrow 7, and from the exhaust port 3 as indicated by an arrow 9. To the outside.

  However, at this time, a part of the desorbed solvent or organic component is not decomposed and may be deposited and deposited as a deposit 6 on the connection portion of the exhaust port 3. Depending on the degree, the exhaust port 3 is clogged. There is a fear. As a result, since the atmosphere in the atmosphere furnace 2 is contaminated and the atmosphere state changes, the characteristics of the calcined film to be formed change, and it becomes difficult to form a calcined film with uniform characteristics.

  In addition, the deposit 6 may drop and adhere to the oriented metal substrate 1 from the exhaust port 3, which adversely affects the formation of a calcined film having uniform characteristics.

  For this reason, it is necessary to clean the part contaminated by the deposit 6, resulting in a decrease in productivity.

  And when this calcination heat treatment is performed using such a calcined film, an oxide superconducting thin film having uniform characteristics cannot be formed, and the superconducting characteristics vary.

  Therefore, in the invention of this claim, the calcination heat treatment is performed using an atmospheric furnace in which an oxidation catalyst is disposed at the exhaust port. For this reason, the desorbed solvent and organic components are completely oxidized and decomposed into water and carbon dioxide, so that the exhaust port 3 is not clogged and the atmosphere in the atmosphere furnace 2 is not polluted. Moreover, the deposit does not fall on the oriented metal substrate. As a result, the calcining heat treatment can be performed in a stable atmosphere, and a calcined film having uniform characteristics is formed over a long length from the start end to the end, and in the subsequent main annealing heat treatment, uniform characteristics from the start end to the end. An oxide superconducting thin film is formed. Moreover, productivity is improved because it is not necessary to remove deposits and to clean contaminated parts generated in the atmosphere furnace.

The invention described in claim 2
The method for producing an oxide superconducting thin film wire according to claim 1, wherein the oxidation catalyst is a platinum catalyst.

  The oxidation catalyst is not particularly limited as long as it is a catalyst capable of oxidatively decomposing a solvent and organic components that are effectively desorbed in the temperature range of the calcining heat treatment. Can be mentioned. Among these, a platinum catalyst is preferable because it is excellent in heat resistance and catalytic activity.

The invention according to claim 3
_{3. The} method for producing an oxide superconducting thin film wire according to claim 1, wherein the oxide superconducting thin film wire is a YBa ₂ Cu ₃ O _7-X oxide superconducting thin film wire. 4.

In the production of a YBa ₂ Cu ₃ O _7-X oxide superconducting thin film wire, the above-described effects are remarkably exhibited.

  According to the present invention, in the production of a long oxide superconducting thin film wire using the MOD method, it is possible to form an oxide superconducting thin film having uniform characteristics from the start to the end, and to provide a long and stable superconducting characteristic. An oxide superconducting thin film wire can be produced.

It is a figure which shows the outline | summary of the calcination heat treatment process in the manufacturing method of the oxide superconducting thin film wire of embodiment of this invention. It is a figure which shows the outline | summary of the calcination heat treatment process in the conventional MOD method.

  Hereinafter, the present invention will be described based on embodiments.

1. Manufacturing Method of Oxide Superconducting Thin Film Wire (1) Atmospheric Furnace Used in Manufacturing Method of Oxide Superconducting Thin Film Wire FIG. 1 is an outline of a calcination heat treatment step in the manufacturing method of an oxide superconducting thin film wire according to an embodiment of the present invention. FIG. As shown in FIG. 1, a long oriented metal substrate 1 having a coating film of a raw material solution made of a metal organic compound on its surface is placed longitudinally in an atmosphere furnace 2 (electric furnace) as indicated by an arrow 10. It is inserted and transported at a predetermined speed.

  The atmosphere furnace 2 has a cylindrical shape with a diameter of 10 to 20 cm and a length of 4 m, and includes a cylindrical exhaust port 3 and a gas inlet port 8 made of SUS. In the present embodiment, a platinum catalyst 5 (platinum carrying filter) is further arranged near the inlet of the exhaust port 3. The oriented metal substrate 1 is heated to a heat treatment temperature (about 500 ° C.) in an atmosphere of a mixed gas 4 of nitrogen and oxygen introduced from the gas inlet 8.

  At this time, the desorbed solvent and the decomposed gas obtained by decomposing the organic components, and the solvent and organic components that cannot be decomposed are sent to the exhaust port 3 as shown by the arrow 7. And organic components are not completely deposited and deposited on the connection part of the exhaust port 3, but are completely oxidized and decomposed by the platinum catalyst 5 into water and carbon dioxide. As shown by the arrow 9, it is discharged to the outside.

  As a result, the atmosphere in the atmosphere furnace 2 is not polluted, and deposits do not fall on the oriented metal substrate, so that a calcined film having uniform characteristics can be formed from the start to the end. Is done. Then, by subjecting the calcined film to a main annealing heat treatment, an oxide superconducting thin film having uniform characteristics from the start to the end is formed, and a long oxide superconducting thin film wire having no variation in superconducting characteristics can be obtained.

2. Example (1) Preparation of MOD Solution Starting from each acetylacetonate salt of Y, Ba, and Cu, synthesis was performed at a ratio (molar ratio) of Y: Ba: Cu = 1: 2: 3, and alcohol was used as a solvent. A MOD solution was prepared. The total cation concentration of Y ³⁺ , Ba ²⁺ and Cu ²⁺ in the MOD solution was 1 mol / L.

(2) Production of coating film By providing an intermediate layer (total thickness: 1 to 2 μm) of CeO ₂ , YSZ and CeO _{2 in} order on the surface of an oriented metal substrate having a thickness of 100 μm × width 3 cm × length 200 m, An oriented metal substrate was produced. A MOD solution was applied on the oriented metal substrate and then dried to prepare a coating film having a thickness of 1.8 μm.

(3) Calcining heat treatment A cylindrical shape having a diameter of 20 cm and a length of 4 m, and using an atmosphere furnace provided with a SUS cylindrical exhaust port and a gas inlet, N ₂ and O ₂ are contained in the atmosphere furnace. While supplying a mixed gas (N ₂ : O ₂ = 3: 1), the mixture was heated at 500 ° C. for 2 hours to produce a calcined film having a thickness of 0.4 μm. Note that a platinum catalyst having an outer diameter of 3 mm and a length of 100 mm was disposed at the exhaust port, and the amount of exhaust gas discharged from the exhaust port of the atmosphere furnace was set to 10 L / min.

(4) Main calcination heat treatment The produced calcined film was further heated at 800 ° C. for 1.5 hours to produce a Y ₁ Ba ₂ Cu ₃ O _7-δ oxide superconducting thin film having a thickness of 300 nm. An oxide superconducting thin film wire was obtained.

(Comparative example)
A long oxide superconducting thin film wire was obtained in the same manner as in the example except that the oxidation catalyst was not disposed in the atmospheric furnace.

(Observation in atmosphere furnace and calcined film)
In the examples and comparative examples, after the formation of the calcined film was completed, the inside of the atmosphere furnace was observed to confirm the presence or absence of abnormality, and the state of the produced calcined film was observed.

  As a result, in the case of the example, no abnormality was observed in the atmosphere furnace including the periphery of the exhaust port, and a uniform calcined film was formed. On the other hand, in the case of the comparative example, it was confirmed that deposits adhered to the periphery of the exhaust port and the exhaust port was narrowed. Then, when this deposit was analyzed, it was found to be an organic component desorbed from the raw material solution. Also, abnormalities were observed in some places on the surface of the calcined film, which was not uniform.

  As described above, the effect of arranging the platinum catalyst in the atmosphere furnace was confirmed.

(Measurement of Ic)
When Ic of each obtained oxide superconducting thin film wire was measured, it was 10 A / cm in the case of the comparative example, and 60 A / cm in the case of the example, which was superior in superconducting characteristics as compared with the case of the comparative example. It was found that an oxide superconducting thin film wire can be obtained.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to said embodiment. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1 Oriented metal substrate 2 Atmosphere furnace 3 Exhaust port 4 Mixed gas 5 Platinum catalyst 6 Deposit 7 Arrow which shows flow of organic components, etc. 8 Gas inlet 9 Arrow which shows the exhaust direction of carbon dioxide etc. 10 The conveyance direction of oriented metal substrate Showing arrow

Claims (3)

Using a metal organic compound as a raw material, an oxide superconducting thin film wire is produced by forming an oxide superconducting thin film by a coating pyrolysis method using an atmospheric furnace, and a method for producing an oxide superconducting thin film wire,
A coating film production step of producing a coating film by applying a solution of the metal organic compound on an oriented metal substrate;
A calcining heat treatment step for producing a calcined film by thermally decomposing and removing an organic component contained in the metal organic compound of the coating film;
A calcination heat treatment step of crystallizing the calcined film to produce an oxide superconducting thin film,
The method for producing an oxide superconducting thin film wire, wherein the calcining heat treatment step is a heat treatment step of heating in an atmosphere furnace in which an oxidation catalyst is disposed at an exhaust port.   The method for producing an oxide superconducting thin film wire according to claim 1, wherein the oxidation catalyst is a platinum catalyst. _{3. The} method for producing an oxide superconducting thin film wire according to claim 1, wherein the oxide superconducting thin film wire is a YBa ₂ Cu ₃ O _7-X oxide superconducting thin film wire.

Images