JPH03237073A - Joining method for ceramics superconductive material - Google Patents

Abstract

PURPOSE:To join the ceramics superconductive materials without deteriorating the superconductive characteristics by interposing the specified amorphous substance between the ceramics superconductive materials to be joined and heat-treating them. CONSTITUTION:In the case of joining the superconductive materials 1 consisting of a ceramics superconductor with each other, amorphous substance 2 described hereunder is interposed between the superconductive materials 1 and the prescribed heat treatment is performed for these. The amorphous substance 2 has composition wherein at least a metallic component is same as the above- mentioned ceramics superconductor and its melting temp. is lower than the ceramics superconductor. The amorphous substance 2 is produced by melting substance for a raw material capable of being formed into the ceramics superconductor, quenching and coagulating this. As the quenching and coagulating method, various methods such as a single roll method, a twin roll method, a piston anvil method, a rotational submerged spinning method and an atomization method are utilized. Further as the shape, an arbitrary shape such as a sheet shape, a fibrous shape and a powdery shape is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for joining ceramic superconducting materials.

[Conventional technology and its issues]

In recent years, Y-Ba-Cu-0, which exhibits superconductivity at liquid nitrogen temperature, has been developed.
Ceramic superconductors such as the B1-3r-Ca-Cu-0 series and the B1-3r-Ca-Cu-0 series have been discovered, and research on their practical application is progressing in various fields.

By the way, as a method of joining these ceramic superconducting materials, for example, a method of interposing a plate 3 as a joining medium in FIG. 3A2 has been used.

However, according to this method, since solder is a normal conductor,
There was a problem in that the resistance of the connection part increased and high superconducting properties could not be obtained as a whole of the ceramic superconductor.

For this reason, a method has been proposed in which ceramic superconducting materials are pressed together and heated and melted to join them, but this method causes compositional fluctuations in the ceramic superconductor and deteriorates its superconducting properties. There was a problem.

[Means to solve problems]

The present invention has been made in view of this situation, and as a result of intensive research, it has been found that the amorphous material of the Cerax superconductor composition has a melting temperature (melting point) of up to 100% higher than that of a crystalline material exhibiting superconductivity.
If this amorphous material is used as a bonding medium instead of solder, the bonding temperature can be lowered so that the Cera4Tx superconductor will not deteriorate, and this amorphous material will crystallize after welding and become a superconductor. After discovering that, the present invention was completed by further research.

That is, the present invention': In a method for joining superconducting materials made of ceramic superconductors, the superconducting materials have at least the same composition of metal components as the ceramic superconductor and a melting temperature of the ceramic superconductor. This is a method for joining ceramic superconducting materials, which is characterized by interposing a lower amorphous material and subjecting it to a predetermined heat treatment.

In the method of the present invention, the composition of the amorphous substance may be the same as that of the ceramic superconductor constituting the ceramic superconducting material to be bonded, or at least the metal component may have the same composition. It crystallizes and becomes a superconductor. or,
The above-mentioned amorphous material is produced by melting a raw material that can be made into a ceramic superconductor and rapidly solidifying it. Rapid solidification methods include the single roll method, twin roll method, piston anvil method, and rotating liquid method. Various methods such as the intermediate spinning method and the atomization method are used, and any shape such as sheet, fiber, powder, etc. can be used.

In the method of the present invention, when an amorphous substance is interposed between the ceramic superconducting materials and the materials are heat-treated and bonded, it is preferable to heat-treat the superconducting materials while pressing them together, as this improves bonding strength and the like.

[Effect]

In the method of the present invention, an amorphous substance having the same composition as the superconducting material and having a lower melting point than the superconducting material is interposed between the ceramic superconducting materials, and the amorphous substance melts and the superconducting material does not melt. Since the ceramic superconducting material is bonded by heating to a high temperature, the heating during bonding will not deteriorate the ceramic superconducting material, and since the amorphous material becomes a superconductor after bonding, the resistance of the bonded portion will not increase.

〔Example〕

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

Example 1 Bi2O3, SrCO3, CaCO3, and CuO are blended and mixed in a molar ratio of 2:2':1:2, and then calcined in the atmosphere, then pulverized and classified, and calcined. It was made into powder. Next, this calcined powder is 5x5x50m
It is compacted into a bar with a diameter of
The material was heated and sintered at 840°C (just below 50°C) for 30 hours to form a ceramic superelectric 4-bar material.

On the other hand, as an amorphous substance for bonding the ceramic superelectric four-bar material, the pre-sintered powder was heated and melted at 200°C, and then rapidly solidified by a twin roll method to produce a sheet with a thickness of 30 μm. did.

Then, two of the ceramic superconducting rod materials are prepared, and as shown in FIG. 1, the sheet 2 is placed between the superconducting rod materials 1
was placed in between and heated to 800°C to join the superconducting rod materials together. For joining, various pressing forces were applied between the bars.

Example 2 The same pre-calcined powder as produced in Example 1 was heated to 1200°C.
The average particle size is 10 by the atomization method.
The same method as in Example 1 was used except that the powder was made into a powder of μm in size, then compacted into a plate of 0.2 mm to form a plate, and this was interposed between the ceramic superconducting bars. Tux superconducting rod materials were joined together.

In Examples 1 and 2, it was confirmed by X-ray diffraction that the sheet and powder were amorphous.

The melting points of both were 780°C.

Comparative Example Work Two pieces of the ceramic superconducting rod materials produced in Example 1 were brought together, and the abutted portions were heated at 860° C. for 2 hours in the atmosphere while being pressed from both sides to join the superconducting rod materials.

Comparative Example 2 Ceramic superconducting rod materials were soldered together in the shape shown in FIG. 1 using In-3n solder.

The critical current density (Jc) of each of the thus obtained joined bodies of four ceramic superconductor materials was measured in two ways: a part including the joint and a part not including the joint. In addition, the bonding strength of the portion including the bonded portion was measured by a tensile test.

Jc was measured in liquid nitrogen (77K) without a magnetic field. The results are shown in Table 1.

As is clear from Table 1, the products manufactured by the method of the present invention (Nos. 1 to 6)
) showed that the part containing the joint had almost the same high Jc value as the part not containing the joint. In addition, the strength of the joint was high enough to be practically acceptable.

In the above cases, pressure is applied during bonding in general.
c and bonding strength both showed high values.

In contrast, those bonded directly without using a bonding medium (No.
In case 7), not only the joint but also the entire superconducting rod material exceeded the melting point, resulting in compositional fluctuations and an overall decrease in Jc.In addition, in the case where solder was used as the joining medium (No. 8), solder was always used. Since it is a conductor, the IC of the joint has decreased.

1. We have explained the joint structure shown in Figure 1, but as shown in Figure 2 A to C, it is possible to make the joint surface oblique (Figure A) or fit it (Figure 2). It is also possible to increase the bonding strength by increasing the area, or to cover and reinforce the bonded portion with a highly conductive metal material or solder (see figure).

Furthermore, the method of the present invention can be applied to any ceramic superconductor such as the Bi-based superconductor used in the above embodiments, as well as the aforementioned Y-based or Tl-Ba-CaCu-0 based superconductors.

〔effect〕

As described above, according to the method of the present invention, ceramic superconducting materials can be bonded together without impairing superconducting properties such as Jc, resulting in significant industrial effects.

[Brief explanation of drawings]

1 and 2A to 2C are cross-sectional views showing embodiments of the joining method of the present invention, and FIG. 3A and 3B are cross-sectional views showing a conventional joining method. 1-Nana Ugonox superconducting rod material, 2-Amorphous sheet, 3-111 solder.

Claims (1)

[Claims] In a method for joining superconducting materials made of ceramic superconductors, an amorphous substance having at least the same composition of metal components as the ceramic superconductor and having a melting temperature lower than that of the ceramic superconductor is interposed between the superconducting materials. 1. A method for joining ceramic superconducting materials, the method comprising: applying a prescribed heat treatment to the ceramic superconducting materials;