JPH013099A - Method for manufacturing superconducting materials - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing superconducting materials.

The superconducting material produced by the method of the present invention can be used in magnetic levitation trains, medical diagnostic tomography ffl imaging devices (nuclear magnetic resonance CT, π
It is used as a superconducting magnet material for meson irradiation therapy bags (j4), nuclear fusion reactors, power storage, electric rotating machines (motors, generators), and superconducting base materials for Josephson elements.

(Prior art) Examples of superconducting materials include metal elements, alloys of stiff metals, intermetallic compounds, organic materials, and ceramics.Recently, La-5r-Cu oxides, Y-Ba-Cc+
Boiling point of liquid nitrogen for ceramics such as J5 oxide (
Basic research is progressing on so-called high-temperature superconducting materials that exhibit superconducting properties even at temperatures higher than 77K.

On the other hand, research is progressing on the practical application of these materials.
Superconducting wires, strips, and plates used in electromagnets and other devices are being prototyped. Superconducting materials such as intermetallic compounds and ceramics are extremely hard and brittle, so it is difficult to turn the superconducting materials themselves into wires. Therefore, industrially, it is necessary to use a powder material mixed in a proportion corresponding to the composition of a superconducting material, fill it into a tubular body, etc. to form a wire rod, and then heat-treat it to generate a superconducting material. often.

(Problems to be Solved by the Invention) However, there are the following problems in producing a superconducting substance using a powder material.

In the conventional technology of filling a powder material into a tubular body or the like and subjecting it to heat treatment to generate a superconducting material, the reaction site of the superconducting material is limited to the contact area between the powder materials. It requires a long heat treatment to produce it, and there is also the problem that unreacted substances tend to remain.

In addition, it is technically extremely difficult to uniformly stir and mix powder materials due to differences in specific gravity and particle size distribution of the materials, and due to the non-uniformity of this material, the wire material manufactured has poor superconductivity. The problem arises that the superconductivity is poor or even that the superconductivity is not exhibited.

Therefore, the present invention seeks to provide a method for manufacturing wires, plates, and other superconducting materials exhibiting excellent superconducting properties.

(Means for Solving the Problems) The present invention uses a high energy density heat source to melt and solidify a mixed powder material to improve its uniformity and completely proceed with the reaction, thereby producing a superconducting material with excellent properties. The present invention provides a method for manufacturing.

The method for producing a superconducting material according to the present invention includes amorphousizing a granular material blended with a ceramic superconducting material composition by melting and solidifying it using a high energy density heat source.
Next, the amorphous material is subjected to crystal formation heat treatment.

As the powder material, a material is selected depending on the components of the superconducting material to be produced. For example, if the conductive material is Y −
In the case of a 11a-Cu-based oxide, a powder mixture of Y2O3°11aCO3, CuO is used. The powder material is preferably calcined in advance to remove CO2 and impurities.

Here, high-density energy heat sources mean electron beams, laser beams, and plasma heat sources. In order to apply a high-density energy heat source to a granular material, the granular material is filled in a tubular body or spread on a plate and irradiated with a high-density energy flow.

As the material for the tubular body used here, a material with a melting point higher than the melting temperature of the powder material mixed in the superconducting composition is selected, so that the tubular body does not melt when irradiated with a high-density energy heat source, and the powder material inside melts. I'll do what I do.

To make the material amorphous, it is heated to, for example, 1200° C. and then rapidly cooled at a cooling rate of about 2° C./sec. In addition, the crystal formation heat treatment is performed by heating to, for example, 950°C, and
Hold for several hours and slowly cool. It is not necessary for all of the raw material to be amorphous when this mixed powder and granular material is made amorphous.

In the heat treatment for producing crystals exhibiting superconductivity, the heat source is not particularly limited, and may be, for example, a conduction heating furnace or a combustion gas furnace. Further, the crystal formation heat treatment can be performed by providing a continuous online heat treatment device, or by performing batch processing using a separately prepared heat treatment device after melting and solidifying treatment using a high energy density heat source.

Preceding crystallization heat treatment, the wire material is subjected to cold treatment as necessary.
Warm or hot working is also possible.

(Function) According to the present invention, the mixed powder and granular material is once melted and then solidified, so even if the mixed powder and granular material has some degree of non-uniformity, the uniformity and properties of the material are maintained. It increases dramatically. Furthermore, if the powder material is made amorphous by utilizing the rapid solidification process that is a characteristic of high-density energy heat sources,
It is also possible to avoid local segregation during solidification, further improving the uniformity of the material. In addition, for materials that have been melted and solidified to form a continuum, the reaction area during heat treatment to produce superconducting substances is much larger than that when using powdered materials, and the reaction can occur over the entire material area in a short time. Completely complete. Further, since the amorphous portion is a metastable phase, a superconducting material that is a stable phase can be formed in a shorter time by heat treatment. Therefore, according to the present invention using a high-density energy heat source, a superconducting material with far superior properties can be obtained in a much shorter time than superconducting materials obtained by conventional methods. Furthermore, if the mixed powder material filled in a tubular body or spread on a plate is continuously melted and solidified using a high energy density heat source, a continuous amorphous layer is formed, resulting in the formation of a long It becomes possible to manufacture superconducting wires that exhibit uniformly excellent superconducting properties over the entire area and superconducting substrates that have uniform superconducting properties.

(Example 1) A mixed powder of Y2O3, BaCO3, (:uO) blended in an atomic ratio of Y:Ba:Cu = 1:2:3 was placed in a stainless steel cylindrical container with an outer diameter of 25 mm and a wall thickness of 5 mm. After filling the inside of the wire and welding and sealing both ends, the outer diameter was reduced by cold drawing to obtain a wire rod with an outer diameter of 3 m01.A part of the wire rod was melted and solidified using a high energy density heat source according to the present invention. jyts L/, which was made amorphous and then subjected to crystal formation heat treatment in a tube furnace.On the other hand, as a comparative material, a wire rod that had been subjected to the conventional jet heat treatment in a tube furnace was prepared using some other materials. .

Using an electron beam as a high-energy density heat source and using the conditions shown in Table 1, the superconducting material in the stainless steel container was transformed into a homogeneous amorphous state by continuously feeding wire into the electron beam stream. did. In addition, the heat treatment conditions using the tube furnace are as follows: The heating temperature is 95% for both the present invention and the conventional method.
The superconducting properties of the wire were investigated at 0°C for various holding times. The results are shown in Table 2.

As is clear from Table 1 and Table 2, the sample according to the present invention exhibits perfect superconducting properties at liquid nitrogen temperature (77K) even during short heat treatment times, and the effect of melting and solidification treatment using a high energy density heat source is It's clearly visible. On the other hand, with conventional methods, excellent superconducting properties cannot be obtained even by long-term heat treatment.

In this way, the melting and solidification process using a high-energy density heat source dramatically increases the homogenization of the material and the production rate of superconducting materials compared to conventional methods, making it possible to produce superconducting wire with excellent properties in a short heating time. can.

(Example 71!i Example 2) The same mixed powder as in Example 1 was uniformly sprinkled to a thickness of 100 um on a copper plate with a wall thickness of 3+ nm, a width of 10 mm, and a length of 20 mm. This powder layer was irradiated with a laser beam under the conditions shown in Table 3 to undergo melting and solidification treatment.

The mixed powder layer on the copper plate in Table 3 is once melted in the rapid heating and rapid cooling process by a laser beam, and then becomes amorphous. Thereafter, crystal formation heat treatment was performed at 950° C. for 1 hour in a tube furnace. The melted and solidified layer produced by the laser beam reaches the critical temperature of superconductivity of 90 degrees, which is critical? 5 flow density 382
It exhibited excellent superconducting properties of 0 A/cm2.

(Effects of the Invention) According to the present invention, the material is homogenized by melting and solidifying treatment using a high energy density heat source, and the critical temperature and critical current density can be improved. Additionally, the production rate of superconducting materials is dramatically increased compared to conventional methods, and superconducting materials can be produced with short heating times. As a result, a superconducting material exhibiting excellent properties can be provided at a low cost.

Claims (1)

[Claims] Production of a superconducting material characterized by making at least a part of a powder material blended into a ceramic superconducting material composition amorphous by melting and solidifying using a high energy density heat source, and then subjecting the amorphous-containing material to crystallization heat treatment. Method.