JPH01169820A - Manufacture of oxide superconductive wire - Google Patents

Abstract

PURPOSE:To provide an oxide superconductive wire with great critical current density by supplying a molten oxide to become superconductor to between two metal tapes to be supplied to between a pair of rolls rotating. CONSTITUTION:Two metal tapes 2A, 2B running are supplied to between a pair of rolls 1A, 1B rotating, and a molten oxide 4 to become superconductor is supplied to between these metal tapes 2A, 2B, followed by rapid cooling and solidification to provide an oxide superconductive wire. Different sizes (width and thickness) can be given to the wire by controlling the supply amount of molten oxide, speed of metal tapes and rolls, and the spacing of rolls. The wire 6 thus obtained is equipped with an enhanced density, and an oxide type superconductive wire having a great critical current density can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for producing an oxide-based superconducting wire, and in particular a thin plate having a high density and a high value of critical current density (J,). The present invention relates to a method for manufacturing an oxide-based superconducting wire body.

[Conventional technology and its problems]

Oxide-based superconductors made of alkaline earth metals, rare earth elements, copper, and oxygen have high critical temperatures (T), and are expected to be used for this purpose. However, oxide-based superconductors are generally processed into linear shapes. However, in order to make a wire, a metal tube made of silver, silver alloy, copper alloy, etc. is filled with oxide powder material that will become a superconductor, and then the wire is drawn, swaged, grooved roll, or flat rolled. The wires or thin plates were cold-worked into wires or thin plates to obtain wires of desired dimensions, and then heat-treated to produce oxide-based superconducting wires.

Other methods have also been attempted, such as kneading the oxide powder and binder and then forming it into a wire rod through extrusion processing, or coating it on the outer periphery of the core material and then performing heat treatment including removal of the binder. It is being

[Problem that the invention seeks to solve]

However, in these methods, since oxide powder is used as the material that becomes the superconductor, even if processing is performed with a high area reduction rate, the density of the superconducting wire after heat treatment is not the same as its true density. There was a problem that a value close to the density could not be obtained, and therefore the critical current density (Jc) was low.

[Means for solving problems]

The present invention has been made as a result of intensive studies in view of the above points, and its purpose is to provide a method for manufacturing an oxide-based superconducting wire having high density and a high critical current density (JC) value. It is to provide.

That is, in the present invention, two rotating rolls are moved between a pair of rotating rolls.
At the same time as supplying two metal tapes, a melt of an oxide which becomes a superconductor is supplied between the two metal tapes,
This is a method for manufacturing an oxide-based superconducting wire, which is characterized by cold solidification.

In the present invention, as a method for obtaining a melted oxide that becomes a superconductor, a powder material of the oxide that becomes a superconductor may be melted using a crucible, or the oxide may be formed into a rod and the rod may be melted. It may also be obtained by heating the tip locally to melt it.

In the former, the material of the crucible for melting the oxide powder material is, for example, pure metal such as W, Mo, etc.
, those made of oxides such as MgO and other ceramics,
It reacts with the molten oxide that becomes the superconductor and changes the properties of the oxide, or the reaction with the molten oxide is so severe that it cannot withstand multiple uses. platinum, iridium or alloys thereof (e.g. PL
-Rd, etc.) are particularly preferable because they do not have this tendency. Also, if the holding temperature of the oxide melt is less than 1200°C, the solution becomes extremely viscous and has poor moldability.
If the temperature exceeds 00°C, the reaction with the crucible material will be significant and the life of the crucible will be shortened, so the temperature of the melt should be set at 1200°C.
It is desirable to keep the temperature within the range of ~1500°C.

As a heat source for melting the oxide powder material filled in the crucible, high frequency induction heating, electric furnace, infrared heating, etc. can be used as appropriate.

In the latter method, in which the oxide is made into a rod and the tip of the rod is locally heated and melted, the heating temperature is 12
If the temperature is below 00°C, the resulting melt will be an extremely viscous solution with poor moldability, and if it exceeds 1,600°C, the amount of oxygen vacancies in the oxide will be too large, causing the resulting filament to Even if heat treatment is performed in an oxygen atmosphere, it is difficult to supply the amount of oxygen necessary to develop a superconducting state, or it takes an extremely long time. It is desirable that the temperature be within the range of 1200 to 1600°C.

In addition, as a means for locally heating the tip of the oxide rod body, for example, heating by laser, high frequency, infrared rays, etc. can be used, and as the tip of the rod melts and falls, It is desirable to take measures such as moving the rod downward or moving the heating source such as a laser upward.

Examples of the metal tape used in the method of the present invention include Ag,
Preferably, the material is Ag alloy, Cu alloy, 5tJS, Ni, or the like.

Furthermore, in the method of the present invention, it is possible to obtain filaments of various dimensions (width and thickness) by controlling the amount of molten oxide supplied, the speed of the metal tape and rolls, the gap between the rolls, etc. be. By appropriately heat-treating the filament thus obtained, an oxide-based superconducting filament is manufactured.

In this case, the strips can be heat-treated after being slit in the length direction, or a plurality of strips can be laminated and heat-treated.

Next, embodiments of the present invention will be specifically described using the drawings. FIG. 1 is an explanatory diagram showing an example of the method of the present invention,
A and IB are rolls, 2A and 2B are metal tapes, 3 is a crucible, 4 is a melted oxide that becomes a superconductor, 5 is a heater, 6 is a formed filament, 7A and 7B are metal tape supply devices (Uncoiler, etc.). In this method, two running metal tapes 2A, 2B are supplied between a pair of rotating rolls IA, IB, and a superconducting material molten in a crucible 3 is placed between the two metal tapes 2A, 2B. This is a method of obtaining a continuous filament 6 in which metal tapes 2A and 2B are composited on both sides of the oxide by supplying a melt 4 of the oxide that becomes the body and rapidly solidifying it.

FIG. 2 is an explanatory diagram showing another example of the method of the present invention,
is an oxide rod that becomes a superconductor, 9 is a laser, and 10
is Chuck. In this method, the tip of an oxide rod 8 held by a chuck 10 is locally heated by a laser 9 or the like, and the molten liquid is heated by a laser beam 9, as in the case of FIG.
This is a method in which the metal tapes are supplied between the metal tapes 2A and 2B and rapidly solidified to form the filament 6.

Here, the oxide rod 8 that becomes the superconductor is manufactured using raw material powder, for example, in the case of Y-Ba-Cu-0 system, Y2O1,
BaC0 and CuO powders, and La-3r-Cu-
In the case of 0 series, L a , 0. , S “COl and CuO
The mixed powder is mixed to have the desired composition and compacted into a rod shape, or the mixed powder is pre-sintered in air or oxygen atmosphere, and then ground in a ball mill. It is best to make it by compacting the powder. Alternatively, such a powder may be melted, cooled and solidified to form a rod-shaped oxide rod.

[Effect]

In the method of the present invention, the oxide powder material or rod that becomes the superconductor is once melted, and then it is supplied between two running metal tapes and rapidly solidified to form a filament. The density of the resulting filament is improved, and an oxide-based superconducting filament having a large critical current density (J) can be obtained.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. By the method shown in FIGS. 1 and 2, a continuous filament 6 was obtained in which metal tapes 2A and 2B were composited on both sides of an oxide that would become a super T1 conductor. The oxide used as the superconductor was Y-B.
a -Cu-0 system, with Y2O1 and Ba as raw materials
cOz, CuO powder was mixed with Y:Ba:Cu in 1:2:3' (
This mixture is then pre-sintered at 900°C for 10 hours in an oxygen atmosphere, and pulverized in a ball mill. In the method shown in Figure 1, the powder is melted as it is. Ta. In the case of the method shown in FIG. 2, the powder obtained by the above method was compacted into a rod shape of 10 mmφ, and then this rod was sintered at 900° C. for 1 hr (Jij) in the atmosphere. In the case of the method shown in FIG. 2, the oxide rod 8 was moved downward by the chuck 10 as the tip of the oxide rod 8 melted and fell.

Regarding the above method, the method and melting temperature of the oxide,
The manufacturing conditions such as the material of the metal tape and the material of the crucible in the case of the method shown in FIG. 1 are summarized in Table 1. Further, the obtained filament 6 was subjected to heat treatment for 900'CX10 hr in an oxygen atmosphere to obtain an oxide superconducting filament. Regarding the obtained striatum, the thickness of the striatum, the thickness and density of the superconductor layer in the striatum (ratio to true density, %), critical temperature (Tc), liquid nitrogen temperature ( critical N at 77°K)
, vL density (Jc), and other superconducting properties were measured.

The results obtained are summarized in Table 2.

For comparison, the Y2O3, B a CO3, and CuO powders were weighed and mixed so that Y:Ba:Cu=1:2:3 (mole ratio), and this was heated at 900°C x 10 in an oxygen atmosphere.
After pre-sintering for several hours, the resulting oxide powder was crushed in a ball mill and filled into an Ag pipe with an inner diameter of 6 mm, followed by cold wire drawing to obtain a 0°6 mm composite wire. Subsequently, the composite wire was heat treated at 900°C for 10 hours in an oxygen atmosphere to produce an oxide superconducting wire. Various properties of the oxide superconducting wire thus obtained were measured. The obtained results are also listed in Tables 1 and 2 as Comparative Example 11.

As is clear from Table 2, all of the height measurements 1 to 8 of the present invention manufactured by the method of the present invention have a high density and a critical current density (
An oxide-based superconducting wire body with a large JC) has been obtained.

- In the method shown in Fig. 1, the temperature of the oxide melt was too low in comparison height measurement 9, in which the melt could not be continuously supplied from the crucible, and the temperature of the melt was too high. In Comparative Height Measurement 10, the melt reacted with the crucible and the crucible was damaged, and a filament could not be obtained.

In addition, in Comparative Height Measurement 11, in which wire rods were manufactured using the conventional method, 86
2 showed superconductivity, but because the density of the superconductor was low, the critical current density (Jc) value was significantly lower than in Invention Measurements 1 to 8.

〔Effect of the invention〕

According to the method of the present invention, it is possible to obtain an oxide-based superconducting wire having a large critical current density (JC), which brings about significant industrial effects.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are explanatory diagrams showing an example of the method for manufacturing an oxide-based superconducting wire according to the present invention. l A, I B - one roll, 2A12B - metal tape, 3 - crucible, 4 - oxide melt, 5 - heater,
6-.-striatal body, 7A, 7B-metal tape supply device, 8
- oxide rod, 9- laser, 10- chuck.

Claims (3)

[Claims] (1) Two running metal tapes are supplied between a pair of rotating rolls, and a molten oxide that becomes a superconductor is supplied between the two metal tapes and rapidly solidified. A method for producing a featured oxide-based superconducting wire. (2) A crucible made of platinum, iridium, or an alloy thereof is used to melt the oxide that becomes the superconductor, and the temperature of the molten oxide is within the range of 1200 to 1500°C. A method for producing an oxide-based superconducting wire according to claim 1. (3) The melt of the oxide that will become a superconductor will locally touch the tip of the oxide rod that will become a superconductor at a temperature of 1200 to 160
2. The method for producing an oxide superconducting wire according to claim 1, wherein the molten material is obtained by heating and melting the material within a temperature range of 0.degree.