JPH01241706A - Manufacture of oxide superconductor - Google Patents

Abstract

PURPOSE:To obtain a superconductor wire of a high mechanical strength and excellent superconductivity by making only the part made with powder of B3Cu5Oy melt and diffusion-react with a formed body portion made of a compositional ratio of A2B1Cu1O5. CONSTITUTION:An oxide layer 3 made of A2B1Cu1O5 is compress-formed around a bar-shaped core body 2 made of a metal such as Ni. After forming an oxide layer 4 made of the compositional ratio of B3Cu5Oy on the outer circumferential surface of the layer 3 and filling into a metallic pipe, wire drawing process is performed to obtain a wire material 1. The wire material 1 is then heated at a temperature higher than the melting point of the B3Cu5Oy and lower than the melting point of the A2B1Cu1O5. As a result, only the external layer made of B3Cu5Oy melts and the molten substance diffusion-reacts with the inner layer 3 to form a superconductor layer 6. By further gradually cooling the formed substance, a superconductor wire 7 is obtained. (A is an element of the group IIIa and B is an element of the group IIa.) This makes it possible to manufacture a superconductor wire of an excellent superconductivity and a high mechanical strength.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for producing an oxide-based superconducting wire that can be used, for example, in magnet coils for nuclear magnetic resonance imaging devices, particle accelerators, and the like.

"Conventional technology" Recently, the critical temperature at which the normal conductive state transitions to the superconducting state (
Various oxide-based superconducting materials are being discovered that exhibit a high value of 1rc) higher than the liquid nitrogen temperature.

In order to manufacture a superconducting wire made of such an oxide-based superconducting material, for example, in the case of a superconducting wire comprising a Y-na-Cu-0-based superconductor, Y,03 powder and I3 powder are used.
a A mixed powder of COs powder and CuO powder is filled into a metal pipe made of copper, silver, etc., and then diameter reduction processing and heat treatment are performed sequentially to sinter the mixed powder to make it a superconductor. It is known how to obtain the line.

"Problems to be Solved by the Invention" However, the above method for manufacturing a superconducting wire has the following disadvantages.

In the superconducting wire obtained by this manufacturing method, the superconductor made from mixed powder is produced by sintering, which is a solid phase reaction, so there are many fine pores inside the superconductor. It does not have a high degree of consolidation,
Therefore, there are problems in that high values such as critical current density cannot be obtained especially for superconductors, and mechanical properties are also inferior.

This invention was made in view of the above circumstances, and its purpose is to enable the production of a high-density superconductor close to the theoretical density with zero porosity, thereby exhibiting excellent superconducting properties, Another object of the present invention is to provide a method that makes it possible to manufacture a superconducting wire having high mechanical strength.

"Means for Solving the Problem" In the present invention, in manufacturing a superconducting wire including an oxide superconductor represented by the general formula A-13-Cu-0, an oxide having a composition ratio of AtBtCu+Os is used. A layer is compressed and formed on the outer periphery of a rod-shaped core to form a rod-shaped molded body, and then a layer of oxide having a composition ratio of 113Cu5Oy is formed on the outer peripheral surface of this molded body, and the entire body is used as a precursor. ,
This precursor is then filled into a metal pipe to form a composite,
Next, this composite is wire-drawn to make a wire rod, and then the melting point of n3Cus-Oy is higher than the melting point of n3Cus-Oy.
The solution to the above problem was to produce an oxide-based super 21X conducting wire by heating the wire to a temperature 1 mm lower than the maximum point of CII r Os.

Hereinafter, the method for manufacturing an oxide-based superconducting wire according to the present invention will be explained in detail with reference to the drawings. The example explained here is
The present invention can be applied to Y + Bat C1130X (where x
−7−δ, 0≦δ≦5. ) is applied to a method for manufacturing a superconducting wire equipped with an oxide-based superconductor represented by the composition ratio.

First, oxide powder having a composition ratio of Y*na+10 g of Cu is pressed onto the outer periphery of a small-diameter cylindrical core to form a cylindrical molded body. Here, in order to produce an oxide powder having a composition ratio of Ytna+Cu+Os, Yt-032Ba
Mix raw material powders of CO3 and Cuo at a molar ratio of 1:l:l, and heat this in the air at about 800-950°C for 6-30°C.
After being calcined for about 1 m and slowly cooled, it is crushed to a particle size of 0.1
The powder is made into a powder of about 4 μm. Further, as the core, a metal rod (metal wire) of Ni, Au, Ag, PL, etc. having a melting point of about 950° C. or more is used. Furthermore, in this case, the method for producing the molded body is to prepare the powder into a paste by appropriately adding water or a binder such as organic cellulose to the powder, and apply this to the core to a predetermined thickness. Preferably, a method is employed in which the material is adhered as described above and then compression molded by a hydrostatic pressing method such as a rubber press method.

Next, 111ascusOY was applied on the outer peripheral surface of this molded body.
(However, 5≦y≦15.) An oxide powder having a composition ratio of 5≦y≦15 is applied to form an oxide layer, and the whole is used as a precursor. Here, to produce an oxide powder with a composition ratio of n az Cus Oy, 2BaCO5°CuO
The raw material powders are mixed at a molar ratio of 3:5, and this is calcined in the air at about 800 to 950°C for about 6 to 30 hours, slowly cooled, and then crushed to a particle size of 0.1 to 950°C. Align to about 4μ kan,
Make into powder. Further, as a method for applying this powder to the above molded body, water or a binder such as organic cellulose is appropriately added to the powder in advance, and the powder is thereby prepared into a paste state and is adhered to the above molded body. etc. should be suitably adopted.

Next, this precursor is filled into a metal pipe (combined).The metal pipe is made of a metal such as silver, platinum, palladium, etc., which has a melting point of about 950°C or higher and has oxygen permeability. Although it is preferably used, metals such as copper or alloys such as stainless steel can also be used.

Next, this composite is subjected to a wire drawing process to obtain a TL material as shown in FIG. Here, in FIG. 1, the symbol l is a wire rod, and this wire rod 1 has a core wire 2 made of the above-mentioned core,
The above Y * r3 a + covering the outer periphery of this core wire 2
An inner layer 3 having a composition ratio of Cu 10@, and an outer layer 4 having a composition ratio of n as Cus Oy, which further covers this inner layer 3.
and a metal layer 5 formed by rolling the metal vibrator. In this case, as the wire drawing process, techniques such as wire drawing, rolling using a grooved mouth, and forging are employed.

After that, the melting point of Ymna+Cu+Os (950 to 970°C) is higher than the melting point of nasCu5Oy (about 904°C).
degree) at a lower temperature, that is, at a temperature of about 905 to 950°C! heat up. Then, in the wire l, only the outer layer 54 made of IB as Cus Oy melts, and this melt melts into the inner layer 3 which is simply sintered without being melted.
They diffuse and react with each other, and as shown in Figure 2, Y,
A superconducting layer 6 having a composition ratio of n atc L130 K is produced. Furthermore, by slowly cooling this, a superconducting wire 7 having a superconducting layer 6 is obtained.

In the method for manufacturing such an oxide-based superconducting wire, n
a3 Only the outer layer 4 made of Cus Oy is melted and sealed with U, thereby causing a mutual diffusion reaction with the inner layer 3 to form Y+Ba.
Since the superconductor 56 having a composition ratio of tCusOx is generated, the density of the superconductor in the obtained superconducting layer 6 becomes high and approaches the theoretical density with zero porosity. Moreover, the obtained superconducting IQ7 has sufficiently high mechanical strength because the core wire 2 made of the core body is inserted therethrough.

In addition, in the above example, the present invention is defined as Y+natC□-O
Although an example has been shown in which the present invention is applied to the production of a superconducting wire having a superconductor represented by the composition ratio of The present invention can be applied to manufacturing a superconducting wire having a superconductor having a composition ratio of

Further, although a cylindrical molded body was produced, it may also be formed into a prismatic shape, for example.

"Examples" The present invention will be explained in more detail below using Examples.

First, powders of Y*Os, 11aCOs, and Cuo were mixed at a molar ratio of I:I:I to prepare a mixed powder. Then, this was heated at 950℃ for 24 hours in the atmosphere.
After being calcined for an hour and slowly cooled, it is crushed to a particle size of 0.1 to 1μ.
The powder was prepared into a powder, and organic cellulose was added to the powder to prepare a paste. Then, using a previously prepared cylindrical nickel rod with an outer diameter of 1 mm and a length of 10 cz as a core, the powder prepared into a paste was applied and adhered to the outer circumferential surface of the rod to a thickness of about 7 RJ1, and then a rubber press method was applied. The molded product was molded into a cylindrical shape with an outer diameter of 6R11. In this case, as the above raw material powder, Y!
Os has a purity of 99°99%, and BaCOs
And CuO of 99.9% was used.

Next, [3aCOs (purity 99.9%) and Cu-
0 (purity 99.9%) were mixed at a ratio of 3=5 (mole ratio) to produce a mixed powder. Then, this is calcined in the air at 900℃ for 24 hours, slowly cooled, and then crushed to make a powder with a particle size of 0.1 to 1μ, and organic cellulose is added to this powder to make a paste. This was coated onto the outer circumferential surface of the molded article to a thickness of about 0.5 JIJI, and the adhesion was tightened to 0° to obtain a precursor.

Next, at this time, the outer diameter of the frame was 12 x m and the inner diameter was 8 xx.

A silver pipe with a length of 13 CI is filled into a composite body, and this composite body is then wire-drawn to have an outer diameter of 2.4 x m and a length of 3.25 mm. A wire rod of w was obtained.

Thereafter, this tIa material was continuously heated at a temperature of 920'C to melt only the outer layer part which was applied in the form of a paste, and caused a mutual diffusion reaction with the molded body part to cause Y1
A superconducting layer having a composition ratio of 0a*cusox was produced, and this was further slowly cooled to obtain a superconducting wire.

When we investigated the superconducting properties of the superconductor in the superconducting wire obtained in this way, we found that the critical current density (J
c) showed a value of about 3800 A/cm''.

"Effects of the Invention" As explained above, the method for manufacturing an oxide-based superconducting wire of the present invention melts only the portion consisting of rl 3CusOy powder, thereby A I B r Cu +
Since the superconductor layer having a composition ratio of Ar[3*Cu5OX is produced by a mutual diffusion reaction with the molded body part having a composition ratio of Os, it is different from that produced by sintering, which is a solid phase reaction in the conventional method. It is possible to generate a superconductor layer in a short time compared to , and the density of the superconductor in the obtained superconductor layer can be made sufficiently high to be close to the theoretical density of Kukotei zero, Therefore, it is possible to fabricate superconducting wires with excellent superconducting properties such as critical current density. Furthermore, the obtained superconducting wire has a sufficiently high mechanical strength because the core wire made of the core body is inserted therethrough.

[Brief explanation of the drawing]

Figures 1 and 2 are for explaining a specific example of the method for manufacturing a superconducting wire of the present invention. Figure 1 shows a schematic diagram of the formation of the wire, and Figure 2 shows a schematic diagram of the structure of the superconducting wire. be. ! ...Wire, 2...Core wire, 3...
...Inner layer, 4...Outer layer, 5...Metal layer, 6...Superconducting layer, 7...Superconducting wire.

Claims (1)

[Claims] General formula A-B-Cu-O (where A is Y, Sc, La
, Yb, Er, Ho, Dy, etc., represents one or more elements of group IIIa of the periodic table, and B represents Sr, Ba,
Indicates one or more elements of group IIa elements of the periodic table, such as Ca. A_2B_1Cu
A layer of oxide having a composition ratio of _1O_5 is compressed and formed on the outer periphery of a rod-shaped metal core to form a rod-shaped molded body, and then,
A layer of oxide having a composition ratio of B_3-Cu_5Oy (5≦y≦15) is formed on the outer peripheral surface of this molded body, and the entire body is used as a precursor, and this precursor is then placed inside a metal pipe. The above B_3Cu_5O
A method for manufacturing an oxide superconducting wire, characterized in that the wire is heated at a temperature higher than the melting point of y and lower than the melting point of A_2B_1Cu_1O_5.