JPS63310707A - Production of oxide superconducting powder - Google Patents

Abstract

PURPOSE:To obtain a uniform superconducting powder having high purity and a compsn. coincident with a stoichiometric compsn. by heating a soln. of compds. of elements constituting an oxide superconductor in a solvent and allowing the compd. to react by melting in atomized condition. CONSTITUTION:A soln. L of compds. of elements constituting a superconductor dissolved in a solvent such as ethanol, ether, etc. is charged to a vessel 2. Inert gas such as Ar, etc. is blown into an atomizing pipe 1 from an end of the pipe 1, and the soln. L is discharged in atomized condition and ejected from a tip end of the pipe 1. The atomized soln. is heated at 800-1,100 deg.C by the hot flame generated before the pipe 1, and the powder of an oxide superconductor is formed by allowing the elements contained in the mist for constituting the superconductor to cause a reaction. Suitable soln. L is a soln. contg. a compd. constituted of an element A, element B, Cu, and O, which constitutes an A-B-Cu- O type superconductor (wherein A is Y, Sc, Ce, etc.; B is Ba, Sr, Mg, etc.).

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a method for producing superconducting powder used in the production of superconducting wires and superconducting coils. The present invention relates to a method of manufacturing superconducting powder.

"Prior Art" Conventionally, the method described below has been implemented as a method for manufacturing a superconductor.

One method is a coprecipitation method in which a precipitate is obtained by converting an acetic acid solution or a nitric acid solution containing constituent elements of a superconductor into nitrates, and then drying this precipitate to obtain a precursor of a superconducting powder.

Another method is a powder mixing method in which multiple types of compound powders such as carbonates and oxides of the elements constituting the superconductor are mixed and heated to react with each element to obtain superconducting powder. .

Still another method is the CVD method (chemical vapor deposition method), the MBE method (molecular beam epitaxial method), or
This is a method of forming a thin film superconductor on the surface of a desired base material by a thin film forming method such as MOCVD (Metai Organic CVD).

"Problems to be Solved by the Invention" However, the superconducting powder precursor obtained by the coprecipitation method tends to have a composition that deviates from the stoichiometric composition.
There was a problem in that it was not possible to obtain a perfect superconducting powder with the desired composition. In addition, in the powder mixing method, it is difficult to mix various powders completely uniformly, and because moisture in the air gets mixed in during the mixing process, the superconducting powder obtained after heat treatment is partially may contain superconducting powders with different composition ratios, resulting in a problem of lack of uniformity. Furthermore, the thin film forming method has the problem that it takes a long time to form the film, making it unsuitable for large-scale production of long products such as superconducting coils and superconducting wires.

The present invention was made in view of the above problem, and an object of the present invention is to provide a method for producing a superconducting powder that has a composition that conforms to chemical bond theory, is uniform, and has high purity.

"Means for Solving the Problems" In order to solve the above problems, the present invention dissolves compounds of each element constituting an oxide superconductor in a solvent to obtain a solution, and also forms a mist of this solution. This is to avoid heating and melting reactions in the oxidized state. Further, when performing the heat melting reaction, it is preferable to feed the atomized solution together with a carrier gas into the heat melting reaction section.

"Operation" A superconductor is obtained by atomizing a solution containing the elements constituting the superconductor and causing a heating reaction. Here, the solution is turned into a fine atomized state and melted into a fine state, so that the reaction proceeds uniformly and a superconductor with a uniform composition is produced.

The present invention will be explained in more detail below.

FIG. 1 shows an example of a device used to carry out the present invention. This device includes a container 2 provided in a part of a spray tube 1 by penetrating the peripheral wall of the spray tube I, and a container 2 at the bottom of the container 2. This is a configuration in which the formed through hole 3 is located inside the spray tube l. Then, by introducing a gas such as Ar from one end of the spray pipe l, the liquid stored in the container 2 is atomized and blown out from the through hole 3 of the container, and then blown out from the other end of the spray pipe l. is now possible.

To manufacture a superconductor using the apparatus having the above configuration, a solution containing elements constituting the superconductor is placed in the container 2.

Here, the above-mentioned solution refers to A-B-Cu-0 (however, A
is the periodic table 11 of Y, Sc, La, Ce, Nd, etc.
This is a solution in which a compound of element B, element B, copper, and oxygen, which constitutes a superconductor of the system (indicates a group a element, and B represents an element of group Ua of the periodic table such as Ba, Sr, Mg, and Ca), is dissolved. .

This solution is a nitric acid aqueous solution in which element He, element B, and copper are dissolved, and specific examples of nitrates of these elements include Y (N O3) 3. E r(N O3)! ,
S r(NOs)t, B a(N O3)! , Cu
(N 03)t, etc. Further, as the solution, a solution in which the element is dissolved in ethanol, ether, acetone, etc. can also be used.

If a solution containing the above elements B, B, copper, and oxygen dissolved in a predetermined composition ratio is stored in the container 2 shown in Fig. 1, and an inert gas such as Ar is blown into it from one end of the spray tube l. For example, the solution can be discharged as a mist from the bottom of the container 2, and the mist solution can be discharged from the tip of the spray tube l.

The mist-like solution discharged in this way is heated to 800-1100°C with a heating flame generated at the tip of the spray tube l, and the superconductor constituent elements contained in the mist are reacted to form oxide-based superconducting powder. Generate. Since the atomized solution is heated and melted in an extremely fine mist state, it is sufficiently heated and melted so that the component elements react with each other, and a highly pure superconductor is efficiently produced.

The superconducting powder produced by the above operations is produced by heating an extremely fine mist solution, and in order to completely react in the presence of a sufficient amount of oxygen, it is an excellent superconducting powder with a high critical current. Become. Furthermore, if carrier gas is continuously fed into the spray pipe 1, a predetermined amount of the solution can be continuously atomized, so that continuous production of superconducting powder can be easily carried out. Furthermore, if the flow rate of the carrier gas is quantitatively adjusted, a predetermined amount of superconducting powder can be produced by atomizing a predetermined amount of solution.

Note that the means for heating and melting the atomized solution may be any heating method other than the method using the flame described above.

That is, for example, it is possible to react by heating the metal tube while spraying the atomized solution as described above inside the metal tube.

In order to manufacture a superconducting wire using the superconducting powder manufactured in this way, the superconducting powder is press-molded and filled into a metal tube, and the diameter is reduced.
It can be produced by heating at 1100°C for about 1 to 10 hours.

FIG. 2 shows another example of an apparatus for atomizing and spraying the liquid solution. The liquid contained in the container 12 can be atomized by the ultrasonic oscillator 13 and sprayed to the outside of the container 12.

A solution can also be atomized by using the apparatus shown in FIG. 2, and a superconducting powder can be produced by heating and melting the atomized solution.

“Example 1” 1 mol of Y(N O3)3 and 2.5 mol of S r(N
O3)! A solution is prepared by dissolving 4 moles of Cu(N 03)2 in 10 kg of pure water. Furthermore, this solution is heated to 5°C and atomized using an ultrasonic atomizer.

This atomized solution is mixed with a carrier gas of Ar gas, and then introduced into a CO+OT flame for oxidation reaction to obtain a lump. Since this mass was a porous mass, the peripheral portion was removed to obtain a cylindrical mass with a diameter of 2On+m and a length of 30n+m.

The composition of this cylindrical lump was YSrtCusOx, and the superconductor was obtained by firing this lump at a temperature of about too much°C. The critical temperature Tc of this superconductor was 90K.

"Example 2" 1 mol (7) Y (N O3)3 and 2 mol (D
S r(N O3)t and 3 moles of Cu(NO3)t
was dissolved in 10 kg of pure water and atomized using an ultrasonic atomizer at a temperature of 60°C. Also, the inner diameter is 20
6 mm, outer diameter 30 mm, length 1000 mm steel pipe
Rotate with Orpm. Then, the atomized solution was introduced into the steel pipe using a carrier gas of Ar, and the flow rate was set to I.
It was delivered together with oxygen gas set at Q/cm. When this steel tube was heated to 1100° C. with a heating element made of nichrome wire, approximately 550 g of superconductor having a composition of Y + S rxc u30 x was generated inside the steel tube. A superconducting wire obtained by rolling this superconductor together with a steel pipe and firing at about 1000°C exhibited a critical temperature Tc of 92K.

"Effects of the Invention" As explained above, the present invention uses a solution obtained by dissolving a compound of elements constituting a superconductor in a solvent, atomizes the solution, and causes a heating melting reaction. Each of the atomized particles can be sufficiently heated and reacted, and all of the liquid can be reacted efficiently to produce a uniform and highly pure superconductor. Further, by continuously atomizing the solution and heating and melting it, there is an effect that superconducting powder can be continuously manufactured.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one example of an apparatus used to carry out the present invention, and FIG. 2 is a schematic diagram showing another example of the apparatus used to carry out the present invention. L...Solution, L...Spray pipe, 2...
... Container, 10 ... Spray device.

Claims (2)

[Claims] (1) A method for producing oxide superconducting powder, which comprises dissolving a compound of each element constituting the oxide superconductor in a solvent to obtain a solution, and subjecting the solution to a heat-melting reaction in an atomized state. . (2) Production of the oxide superconducting powder according to claim 1, characterized in that during the heating and melting reaction, the atomized solution is quantitatively fed into the heating and melting reaction section using a carrier gas. Method.