JPH01212747A - Production of thin superconducting composite strip - Google Patents

Abstract

PURPOSE:To easily and inexpensively produce a thin superconducting composite strip by melting an alloy and supplying the metal thereof continuously in the form of a thin film on a substrate consisting of the other metal, then heating the entire part to form a diffused superconducting layer. CONSTITUTION:>=2 Kinds of alloy elements such as Nb-Zr-Ti system are housed in a high-frequency induction furnace 1 and are heated to melt. The molten metal 3 obtd. in such a manner is supplied continuously from a nozzle 2 onto the substrate consisting of a thin strip 4 which is formed of the other metal such as Cu, is un-coiled from a coil 5 and moves at a high speed. The molten metal 3 forms the thin film 3A on the surface of the thin Cu strip 4. The thin film 3A is rapidly solidified to obtain the thin composite strip 4A. The thin composite strip 4A is thereafter subjected to a heating treatment over the entire part to form the diffused superconducting layer between the above-mentioned thin-film like alloy layer and the substrate metal. The above-mentioned heating treatment is otherwise executed in an oxidative atmosphere by which the diffused oxide superconductor layer is obtd. The thin superconducting composite strip having the multielement alloy of a nonequil. phase is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining a thin film of a multi-component alloy superconductor or a multi-component alloy oxide superconductor.

Positive IJL superconducting materials can be used as high-performance energy-related materials such as superconducting magnets, superconducting power transmission, and m-conducting power storage, or as Josephson devices with the characteristics of high speed, high sensitivity, high precision, and low power consumption. It is being put into practical use as an electronics-related material, mainly in A superconducting material is a completely diamagnetic material that, when a metal is cooled to a low temperature, suddenly has zero electrical resistance to direct current, and that it expels magnetic flux from inside and magnetizes in the opposite direction to the external magnetic field. Refers to a substance that becomes a state.

The temperature at which electrical resistance becomes zero is the superconducting critical temperature (Tc)
The Tc of superconducting materials discovered in the past is
For example, pb...7.2K (K is absolute temperature).

Nb...9.3K, Nb3Ga...20.3
1(, Nb3 Ale, +tGe-, ai...41K
, Ba-t, a-Cu-o...35K, S
r -La-Cu-o-...s4K, 8a2V
C+1301...90 or more. The boiling points of helium, hydrogen, neon, nitrogen, and oxygen used to achieve superconductivity are helium...4.1, respectively.
Hydrogen...20.28, Neon...27.102K
, Nitrogen...77.35 K, M element...90.1
High Tc ternary alloy superconductor 44Fl, such as the Nb-Zr-Ti system, does not require the use of helium, which requires a huge amount of incidental equipment such as a liquefier and cooling system when using superconducting materials. , Ba-Ln-Cu-0 system, 5r-Ln
The use of high Tc oxide superconducting materials such as -Cu-0 series and Ba-Y-Cu-0 (note: l-n indicates lanthanide-based elements) is economically extremely advantageous.

By the way, even if a high TC value of a superconducting material is confirmed, it does not mean that the superconducting material will be put into practical use immediately, and it will be possible to form it into usable forms such as wire rods and A-band. Must. Most of the superconducting materials currently in use are bulk wire rods, but the demand for thin strips is increasing.
In the present invention, widely used sputtering method, vapor deposition method, C
Instead of using the VO method, we decided to obtain a ribbon of a non-equilibrium phase multi-component alloy superconducting material or multi-component alloy oxide superconducting material by a melting method.

The purpose of the present invention is to produce 11
The objective is to obtain a thin strip of a multi-component alloy superconducting material or a multi-component alloy oxide superconducting material, which is an equilibrium phase, by a simple and inexpensive melting method.

The purpose of this is to continuously supply molten metal made by melting two or more alloying elements in the form of a thin film onto a substrate made of other metals, rapidly solidify it, and then This is achieved by heating the material to form a superconductor diffusion layer between the thin film alloy layer and the substrate metal.

When two or more alloying elements are slowly cooled and solidified from a molten state, segregation may occur and a material with a uniform structure may not be obtained. Therefore, in the present invention, a molten metal obtained by melting two or more total elements is supplied in the form of a thin film onto a metal substrate and rapidly solidified. An alloy thin film with a uniform and defined composition can be obtained by rapid cooling and solidification treatment, and if the alloy thin film is heat-treated together with a metal substrate, which is another metal, the target composition as a superconducting material can be diffused between the metal substrate and the film. A layer is formed. At that time, if heating is performed in an inert gas atmosphere, a diffusion layer of a multi-component alloy can be obtained, and if heating is performed in an oxidizing atmosphere, an expanded a layer of a multi-component alloy oxide can be obtained. Further, in order to achieve the target composition of the diffusion layer, the heating temperature, heating time, or heating atmosphere may be selected depending on the combination of alloying elements. An example of a multi-component alloy superconducting material is Nb-Zr-Ti, and an example of a multi-component alloy oxide superconducting material is Ba-Zr-Ti.
Ln-Cu-0 series.

5r-Ln-Cu-0 system, 5r-Ca-Ln-Cu-
There is a 0 series.

To form a thin film of molten metal on a metal substrate, it is sufficient to use a long ribbon as the metal substrate, and continuously supply molten metal onto the top surface of the ribbon through a nozzle while moving it at high speed. The thickness of the thin film can be controlled by balancing the supply speed of the metal substrate with the moving speed of the metal substrate. Also,
At this time, if the metal substrate is heated, the molten metal has good wettability to the metal substrate and spreads into a thin film, so if the molten metal is a high melting point metal, the quenching effect is large.

Then, by heating the laminate consisting of the alloy thin film and the gold a substrate to form an expanded rlIm between the metal substrate and the thin film, the desired superconducting composite is produced as a three-layer composite material integrated with the metal substrate. You can get thin strips.

Length-JLJ ■Ba-Ln-Cu-0 based oxide superconducting material (e.g., Ba
In order to obtain (xLa2-xCu04-y), Ba and Ln at a specified ratio are charged into a high frequency induction furnace 1 and melted.

Ba-Ln is a non-equilibrium phase, and its melting point is 1000℃
~1300°C. In the high frequency induction furnace 1, the molten metal 3
(Ba-Ln) is well stirred by magnetic force (Fig. 1).

■ Prepare a coil 5 of copper ribbon 4, which is a third metal, and open the nozzle 2 installed at the bottom of the high-frequency induction furnace 1 while unwinding it at high speed. 3 is ejected (Figure 1). The molten metal 3 spreads into a 719 film shape on the copper ribbon 4 and rapidly solidifies, and the Ba layered on the copper ribbon 4
-Ln thin film 3A is obtained.

■Composite ribbon 4A consisting of Ba-Ln thin film 3A and copper ribbon 4
8 by heating to a temperature of 900°C to 970°C in an oxygen atmosphere.
Hold for ~24 hours. Through this heat treatment, Ba-1,
Ba-1-n-Cu along the interface between the n-thin film product and the copper ribbon 4
-0 diffusion layer 6 is formed, and a composite ribbon 4B having a three-layer structure is obtained.

The features of this embodiment are as follows.

■Ba-1,n, which is difficult to alloy, is supplied as molten metal 3 onto the copper ribbon 4 and rapidly solidified, so Ba-L with a uniform composition
n thin film 3A can be obtained.

(2) The Ba-Ln thin film 3^ can be easily formed by spouting the molten gold R3 through the nozzle 2 onto the copper ribbon 4 moving at high speed. Further, the film thickness can be easily controlled by taking into account the amount of narrowing of the nozzle 2 and the moving speed of the copper ribbon 4.

■The specified copper content and oxygen content in the Ba-Ln-Cu-0 compound can be controlled by the heating temperature and heating time of the composite ribbon 4A, and the superconducting material ribbon with the target composition can be controlled. It is possible to obtain it easily.

■ The obtained composite ribbon 4B with a three-layer structure is used as it is, but during use, when the diffusion layer 6, which is a superconducting material, becomes normal conductive due to magnetic flux jump, the copper ribbon, which is a matrix, becomes a normal conductor. The current is bypassed through the copper ribbon 4, and the heat generated at this time is also effectively dissipated by the copper ribbon 4.

As is clear from the above explanation, according to the present invention, the following effects can be obtained.

■Even if it contains alloying elements that are difficult to alloy with each other,
A thin strip of a multi-component alloy superconducting material or a multi-component alloy oxide superconducting material can be easily and inexpensively obtained by a melting method.

(2) If a gold till plate is made into a long ribbon and molten metal is supplied to the upper surface of the plate while moving it at high speed, it is possible to easily form an alloy ribbon by solidifying the molten metal.

■If a copper ribbon is used as a metal substrate, a composite ribbon with a three-layer structure consisting of an alloy layer of copper ribbon and a superconductor diffusion layer will be used as a superconductor. Even if it becomes normal conductivity due to magnetic flux jump, the current is bypassed to the matrix of the copper ribbon, and the heat generated at this time is also dissipated by the copper ribbon.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing an embodiment of the method of the present invention, and Figure 2 is a composite ribbon with a two-layer structure obtained by the method shown in Figure 1, which is heat-treated to form a superconducting material diffusion layer between the two layers. Three layers II
FIG. 4 is a cross-sectional view of a four-piece composite ribbon. DESCRIPTION OF SYMBOLS 1... High frequency induction furnace, 2... Nozzle, 3... Molten metal, 4... Copper ribbon, 5... Coil, 6... Diffusion layer.

Claims (3)

[Claims] (1) Molten metal made by melting two or more alloying elements is continuously supplied in the form of a thin film onto a substrate made of another metal, rapidly solidified, and the whole is heated to form the thin film alloy layer. A method for producing a superconducting composite ribbon characterized by forming a superconductor diffusion layer between a substrate metal. (2) The method for producing a superconducting composite ribbon according to claim 1, wherein the substrate is a copper ribbon that moves at high speed. (3) The superconductor according to claim 1, wherein the heating is performed in an oxidizing atmosphere to obtain an oxide superconductor diffusion layer between the thin film alloy layer and the substrate metal. Method for producing conductive composite ribbon.