JPH01321031A - Manufacture of oxide superconducting wire - Google Patents

Abstract

PURPOSE:To efficiently obtain oxide superconducting wire excellent in quality by dissolving compound containing constitutive elements of oxide superconductor, then, powdering the solution, attaching the powder to linear substrate, heating, sintering and annealing it. CONSTITUTION:A prescribed quantity of the compound containing each of constitutive elements of oxide superconductor is dissolved in solvent and atomized in a supersonic nebulizer 2 to carry the atomized substance 3 to DMA 5, to select and supply the atomized substance 3 into a reactor 6. The atomized substance 3 is heated in the reactor 6, reacts on oxide superconductor powder, is charged by a link pole 7 for generating an electric field and attached onto the silver wire 8 which is sent out of an uncoiler 14 and charged to a dust collecting pole. This silver wire 8 is passed through the die 10 arranged in a preliminary sintering furnace 9 to smoothen the surface 10, to sinter a powder layer in reserve, then, to be heated, sintered and annealed in sequence in a heating/sintering furnace 11 and an annealing furnace 12 and to obtain an oxide superconducting wire and to be taken up on an uncoiler 15.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing an oxide superconducting wire.

[Conventional technology]

In recent years, oxide superconductors made of oxygen and elements such as alkaline earth metals, rare earth elements, copper, bismuth, and thallium have been discovered.

These oxide superconductors are liquid N! Because it becomes superconducting at temperatures above that temperature, it is much more economical than conventional metal superconductors that exhibit superconductivity at liquid He temperatures, and its use in various fields is being considered.

By the way, the above-mentioned oxide superconductors are brittle and cannot be processed plastically like metal materials. Powder metallurgy is mainly used to process them into wire rods, etc. For example, by converting calcined raw material powder into a paste A method is used in which the coating material is coated on a linear substrate, dried, and then heated and sintered in an oxygen-containing atmosphere.

[Problem to be solved by the invention]

In the powder metallurgy method described above, the method of applying a pasty calcined powder onto a linear substrate requires a long time for drying, and the resulting oxide superconductor layer is porous. There is a problem in that the surface has fine irregularities, and if it is bent during use, cracks will occur, making it impossible to obtain high superconducting properties.

[Means to solve the problem]

The present invention was devised in view of this situation, and an object of the present invention is to provide a method for efficiently manufacturing an oxide superconducting wire with excellent characteristics.

That is, in the present invention, a predetermined amount of a compound containing each of the constituent elements of an oxide superconductor is dissolved in a solvent, and this solution is atomized and supplied to a reactor heated to a predetermined temperature to cause a reaction. While converting the shaped body into oxide superconductor powder,
The oxide superconductor powder generated by creating an electric field inside the reactor is charged, and this charged powder is deposited on a charged linear substrate on a collecting electrode, and then this oxide superconductor powder is deposited. The linear substrate is pre-sintered, passed through a die heated to a predetermined temperature to smooth the surface layer, and then heated and sintered and annealed in an oxygen-containing atmosphere.

In the present invention, examples of compounds containing each of the constituent elements of the oxide superconductor include YBa, C+g0? −6(δ
To illustrate the superconductor of L50.1 to 0.3),
These include acetates, nitrates, halides, or organometallic compounds of Y, Ba, and Cu, respectively.

In the present invention, the method for atomizing the above compound is as follows:
For example, a method may be used in which each of the above compounds is dissolved in a solvent such as water and atomized using an ultrasonic nebulizer or the like.

As a method of continuously supplying the above-mentioned atomized material to the reactor, it is possible to continuously supply the atomized material to the reactor using air, 0! It is preferable to transport the material on a carrier gas such as the like, since the supply amount can be easily controlled.

In the present invention, methods such as electric resistance heating, high frequency induction heating, and burner heating are particularly suitable as heating methods for causing the atomized material to undergo a thermal reaction with the oxide superconductor powder.

In the present invention, as a method for charging the produced oxide superconductor powder, in addition to the electric field charging method, a diffusion charging method can also be applied.

In the present invention, the oxide superconductor powder produced by heating in a reaction furnace includes, for example, Y-Ba-Cu-○-based oxide superconductors such as YBa, Cu, 0. It is a composite oxide represented by the chemical formula, and the above oxide superconductor also contains a composite oxide with an oxygen-deficient composition. In addition, when heat treatment is applied, the superconducting properties are further improved.

In the present invention, a metal or an alloy such as Ag, Ni, or SUS is used for the linear substrate, and this linear substrate is charged as a dust collection electrode to electrostatically adhere the charged oxide superconductor powder. .

The surface layer of the oxide superconductor powder thus deposited on the linear substrate is highly uneven, and this adhered layer is passed through a die heated to a predetermined temperature to smooth the surface and form it into a predetermined shape.

The oxide superconductor powder layer with a smooth surface deposited on the linear substrate is successively heated and sintered in an oxygen-containing atmosphere, and then annealed to form an oxide superconductor wire.

[Effect]

The oxide superconductor raw material is dissolved in a solvent to form a solution, and this solution is atomized and heated to generate a fine oxide superconductor powder.The generated powder is then charged in an electric field, and this charge is Since the powder is electrostatically deposited onto the linear substrate charged with the dust collecting electrode, the generated powder is deposited on the substrate at a high yield, at high speed, and with high density.

In addition, the oxide superconductor powder layer deposited on the linear substrate is
Since it passes through a die heated to a predetermined temperature, the surface becomes smooth and the occurrence of cranks due to bending etc. is prevented.

Furthermore, the oxide superconductor powder with the smoothed surface is heated and sintered and annealed in an oxygen-containing atmosphere to successively bond the powders, supply oxygen, and adjust the crystal structure. Material superconducting wires can be manufactured efficiently.

〔Example〕

The present invention will be explained in detail below using examples.

FIG. 1 is an explanatory diagram of essential parts showing an example of an oxide superconducting wire manufacturing apparatus for carrying out the method of the present invention.

The above device includes an ultrasonic nebulizer 2 for atomizing the raw material solution 1, and a carrier gas control MFC (Mass-Flow-Control) for transporting the atomized material 3.
ler) 4. DMA for particle size selection of the atomized material 3 (D
ifferenLial-Mobili ty-^na
lyzer) 5. Reaction furnace 6 for heating and reacting the selected atomized material 3 to oxide superconductor powder, Link-shaped electrode 7 for generating an electric field for charging the powder, and the charged oxide as described above. A pre-sintering furnace 9 for adhering superconductor powder to a linear substrate 8 serving as a dust collecting electrode and pre-sintering it; and a pre-sintering furnace 9 for smoothing the surface layer of the oxide superconductor powder on the linear substrate 8. 1, a heating sintering furnace 11 and an annealing furnace 12 for heating, sintering and annealing the oxide superconductor powder layer after passing through the dice 10.

In the above, the link-shaped electrode 7 has a structure that allows it to move vertically within the reactor 6, and its position can be controlled depending on the type or amount of oxide superconductor.

Example 1 Y (CHsCOO)s・4H20, B as a starting material
a (CHsCOO)z ・HzO and Cu (CH
3C00)!・Using HtO, convert the above starting material into Y:B
a:Cu was weighed to have an atomic ratio of 1:2:3 and dissolved in water to prepare an aqueous solution with a composition of YBa2Cu3 of 0.03 mol/j2i11 degrees.

The above aqueous solution was set in the ultrasonic nebulizer 2 of the oxide superconducting wire manufacturing apparatus shown in Fig.
atomization at a speed of in, and then this atomized material 3 is
The atomized material 3 was transported to the DMA 5 on an Ot air flow flowing in at a flow rate of 4ffi/T@in, and the atomized material 3 with a particle size of 4 or less was selected by the DMA 5 and supplied into the reactor 6.

The atomized material 3 is heated in the reactor 6 and reacts with the oxide superconductor powder, and is charged by the link-shaped electrode 7 for generating an electric field, and sent out from the uncoiler 14 to form a loam that is charged to the dust collection electrode. 0゜2 traveling at a speed of /H
It was attached onto a 1φ silver wire 8.

In the above, the link-shaped electrode 7 for generating an electric field has a DC20
kv to generate an electric field strength of 8 kv/cm,
The silver wire 8 was grounded via a rotating reel 13.

Then, the silver wire 8 to which the oxide superconductor powder is attached is passed through a die 10 placed in a pre-sintering furnace 9 to smooth the surface of the powder layer, and to pre-sinter the powder layer.
Next, a heating sintering furnace 1 is placed below the preliminary sintering furnace 9.
1 and annealing furnace 12 to sequentially perform heating sintering and annealing to obtain YBazCuzOt-δ (δ = 0.1 to 0.
The oxide superconducting wire of 3) was prepared and wound around the coiler 15. .

In the above, the reaction temperature is 1,000'C1 pre-sintering temperature is 650°C, the die temperature is 600''C1 sintering temperature is set to 900°C, and the annealing is 900°C.
The cooling was performed at a cooling rate of 2''C/min from to room temperature, and the die 10 hole diameter was 2901IgAφ and the entrance diameter was 310-φ.

Example 2 "t'B i (C, H, O,)' 7 as a starting material
H,01Sr (ChHqOb)t ・3HzO1Ca
(C6H90b)t ・5 HzO and Cu (CbH
The above starting material was converted to Bi using qOh)z ・2HzO.
:Sr:Ca:Cu was weighed so that it was 1=1:1:2 and dissolved in a solvent of 50% ethanol and 50% water to prepare a solution of 0.1 mol 1lfa with the composition B15rCaCu. did. Silver wire running speed 15 cra/H1
The reaction rate was 950°C, the pre-sintering temperature was 600°C, the die temperature was 550°C, the sintering temperature was 880°C, and the annealing was 88°C.
An oxide superconducting wire was produced by the same method as in Example I, except that cooling was performed from 0°C to room temperature at a cooling rate of 2°C/++in, the die hole diameter was 275-φ, and the entrance diameter was 2901 rmφ.

Comparative Example 1 Example 1 except that no dice were used in Example 1.
Oxide superconducting wires were manufactured using the same method as described above.

Conventional Example 1 A paste-like pre-sintered powder having a composition of YBa and CuzO was applied to a thickness of 40 μm on a silver wire of 0.2 msφ, and this was heated and sintered at 900°C for 20 hours in an oxygen stream, and then sintered at 900°C.
An oxide superconducting wire was manufactured by slowly cooling the wire from the temperature to room temperature at a rate of 2°C/sin.

The relative density of the oxide superconductor layer of each of the oxide superconductor wires thus obtained was measured. Further, a repeated bending test with a bending curvature of 100R was performed 1°,000 times, and the JC before and after the test was measured. The results are shown in Table 1 along with the main manufacturing conditions.

As is clear from Table 1, the method of the present invention (Example 1.2
) is the comparative method product (Comparative Example 1) or the conventional method product (Conventional Example 1)
), the relative density and Jc of the oxide superconductor layer are higher.

The reason why the Jc of the comparative product after the repeated bending test was extremely low is because the comparative method product was not passed through a die, so the surface layer had severe irregularities, and fine racks were generated from the uneven parts due to repeated bending.

Comparing the products produced by the method of the present invention and those produced by the comparative method, the effect of passing through the die not only smoothes the surface of the oxide superconductor layer, but also contributes to the densification of the superconductor layer or the rearrangement of the crystals. , it can be seen that it contributes to improvement.

Products made using the conventional method have a low J because the oxide superconductor layer is porous, and are brittle, so they break when subjected to repeated bending tests.

[Effect] As described above, according to the method of the present invention, the density is high < J,
Since long oxide superconducting wires with excellent properties can be manufactured continuously and efficiently, this method has a significant industrial effect.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of essential parts showing an example of an oxide superconducting wire manufacturing apparatus for carrying out the method of the present invention. 1... Solution, 3... Atomized body, 6... Reactor,
7... Link-shaped electrode, 8... Linear base, 9.
...Preliminary sintering furnace, 10...Dice, 11...
- Heating sintering furnace, 12... annealing furnace.

Claims (1)

[Claims] A predetermined amount of a compound containing each of the constituent elements of an oxide superconductor is dissolved in a solvent, and this solution is atomized and supplied to a reactor heated to a predetermined temperature to react, and the atomized material is converted into an oxide. The oxide superconductor powder produced by creating a superconductor powder by creating an electric field inside the reactor is electrically charged, and this charged powder is deposited on a charged linear substrate on a collecting electrode, and then this The linear substrate to which the oxide superconductor powder is attached is pre-sintered, passed through a die heated to a predetermined temperature to smooth the surface layer, and then heated and sintered and annealed in an oxygen-containing atmosphere. A method for producing an oxide superconducting wire.