JPH0589729A - Method for manufacturing high-strength ceramic superconductor - Google Patents

Abstract

(57) [Summary] [Objective] To provide a method for easily producing a high-strength ceramic superconductor having excellent superconducting properties. [Constitution] On the Ag coating layer 3 of the ceramic superconducting body 1 having a structure in which the ceramic superconducting layer 2 is coated with an Ag material, a metal powder 4 which reacts with Ag to be alloyed is continuously mounted in the longitudinal direction. Then, the Ag powder 4 placed on the Ag coating layer 3 is heated to form an alloy zone 7 continuous in the longitudinal direction at a predetermined position in the circumferential direction of the Ag coating layer 3. [Effect] Since the Ag coating layer 3 of the ceramic superconductor 1 is continuously alloyed and strengthened in the longitudinal direction, damage to the superconductor layer 2 due to handling or the like is prevented. Further, since alloying is performed in the final step, the drawing process of the composite billet can be easily performed. Moreover, since the alloying of the Ag coating layer 3 is local, good quench resistance is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for easily producing a high-strength ceramic superconductor having excellent superconducting properties.

[0002]

2. Description of the Related Art In recent years, Y- which exhibits superconductivity at liquid nitrogen temperature
Ba-Cu-O system, Bi- (Pb) -Sr-Ca-Cu
Ceramic superconductors such as -O type and Tl-Ba-Ca-Cu-O type have been found, and researches for practical use have been advanced in various fields. By the way, since these ceramics superconductors are fragile, in order to process them into a wire or the like, for example, a metal pipe such as Ag or Cu having a high workability is filled with a raw material capable of forming a ceramics superconductor to form a composite billet. A composite processing method is used in which a composite billet is produced and then drawn to form a wire material having a desired shape, and then the wire material is subjected to a predetermined heat treatment to react the above-mentioned raw material with a superconductor. .. The shape of the ceramic superconducting body manufactured by this composite processing method is circular, elliptical,
It is processed into an arbitrary shape such as a square or tape. And, for example, a required number of the above-mentioned tape-shaped ceramics superconducting bodies are laminated in parallel, concentrically or spirally, or a plurality of ceramics superconducting bodies having a circular cross section are assembled, and then these laminated bodies are laminated. Alternatively, the aggregate is separately filled into a metal pipe prepared separately to form a multi-layer or multi-core composite billet, and the multi-layer or multi-core composite billet is subjected to the same drawing and heat treatment as described above to obtain a multi-layer or multi-core ceramic. A superconductor is manufactured. The above-mentioned ceramics superconductor is used as a pancake type magnet coil by winding it in a spiral shape or as a conductor for a cable by twisting a plurality of coils.

[0003]

However, in the above-mentioned ceramic superconducting body, the metal coating layer is usually composed of a soft pure metal such as Ag and the heat treatment is performed at a high temperature. The resulting ceramic superconductor has a problem that the strength is low and the internal ceramic superconductor layer is cracked during handling, resulting in deterioration of superconducting properties. For this reason, a high-strength Ag alloy was used as the coating material, but in this case, the drawability deteriorates, and the electrical and thermal conductivities decrease, so the quenching resistance during use deteriorates. There was a problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made as a result of intensive studies in view of such circumstances, and an object thereof is to easily manufacture a high-strength ceramic superconducting body having excellent superconducting properties. To provide a way to do. That is, the present invention is to provide a desired number of ceramics superconductor layers on the metal coating layer of the ceramics superconducting body having a structure in which they are collectively coated with a metal material, and a powder or fine wire of a metal to be alloyed with the coating metal is linear in the longitudinal direction. The metal powder or fine wire on the metal coating layer is locally heated to form a high-strength alloy zone continuous in the longitudinal direction in the metal coating layer. It is what

The method of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a process explanatory view showing an embodiment of the method of the present invention. Reference numeral 1 is a ceramic superconductor in which the ceramic superconductor layer 2 is coated with an Ag material. The ceramics superconducting body 1 is made to run at a predetermined speed, and A is coated on the surface of the Ag coating layer 3 of the running ceramics superconducting body 1.
The metal powder 4 which reacts with g to be alloyed is continuously fed from the powder feeder 5 in the longitudinal direction and placed, and then the metal powder 4 placed on the Ag coating layer 3 is placed in front. The metal powder 4 and the surface of the Ag coating layer 3 thereunder are heated by being heated by the laser beam heater 6. This molten region is solidified immediately after leaving the beam of the laser beam heater 6, and an alloy zone 7 is continuously formed in a predetermined portion of the Ag coating layer 3 in the longitudinal direction of the ceramic superconductor 1.

In the method of the present invention, the shape of the metal powder or the fine metal wire to be placed on the ceramic superconducting body is spherical, lump, flat, etc. for the former, and round wire, rectangular wire, etc. for the latter. Can be applied. Further, the finer the particle size or wire diameter of the powder or fine wire is, the more quickly the alloying reaction by heating is performed, which is preferable. The particle size or wire diameter is several to
It is preferably several hundred μm. Any heating method can be applied to the method for heating the metal powder or the fine wire placed on the metal coating layer, but the laser beam heating method is preferable because the local heating can be performed well. Also, as powder or fine wire metal material,
For example, when Ag is used as the coating metal, a metal material such as Al or Ni that forms a high strength alloy with Ag is preferable. Further, instead of the metal such as Al or Ni, an alloy, for example, an alloy having a low melting point based on Ag may be used.

In the method of the present invention, the metal powder or fine wire and the metal coating layer of the ceramic superconductor are most preferably melted and rapidly solidified to form an alloy. Here, it does not matter if the metal powder or the fine wire is thermally diffused in the liquid phase or the solid phase to form an alloy. Also, the placement of metal powder or fine wire and its alloying are
As described with reference to FIG. 1, it is preferable to make the ceramics superconducting body run and continuously to achieve high productivity. In the method of the present invention, the ceramic superconducting body that forms the alloy zone is formed into a composite billet by filling a metal pipe with a raw material (hereinafter abbreviated as raw material) that can be a ceramic superconductor. The composite billet is stretched to form a wire material, and the wire material is subjected to a predetermined heat treatment.

Therefore, the above-mentioned Y-based material, B-based material, and
Starting with i-based and Tl-based ceramics superconductors, an intermediate until reacting with the ceramics superconductor by heat treatment in an oxygen-containing atmosphere, for example, a mixture of constituent elements of the ceramics superconductor, or a coprecipitation mixture, Alternatively, an oxygen-deficient complex oxide in which a predetermined amount of primary raw material powders of oxides or carbonates of the above-mentioned constituent elements are mixed and mixed to form a mixed raw material, and the mixed raw material is calcined is used. In addition, a raw material obtained by melting the mixed raw material, rapidly cooling and solidifying the raw material, and then crushing the raw material is also used. For the metal pipe filled with the raw material, a metal material having high electric and thermal conductivity such as Ag and Cu and having an excellent function as a stabilizing material is used. Particularly, Ag has excellent oxygen permeability. Therefore, the superconducting properties of the obtained ceramic superconducting body are improved, which is preferable. In addition, to fill the metal pipe with the raw material,
In addition to the method of tap-filling the raw material as it is, a method of previously molding the raw material into a predetermined shape by the CIP method or the like and further heating and sintering the molded body to fill the material are applied. It is preferable to process the raw material into a molded body or a sintered body and then to fill the ceramic superconducting body with increased density and improved characteristics such as Jc.

In the method of the present invention, for the stretching process applied to the composite billet, any method such as extrusion, drawing, swaging, rolling, forging, and uniaxial press compression can be applied, but the rolling process or the pressing process is superconducting. The density of the body layer can be further increased. The heat treatment applied to the wire material obtained by drawing the composite billet is performed in order to react the above-mentioned raw material with the ceramics superconductor, and the heating temperature is usually, for example, in the case of Bi-based ceramics superconductor. The temperature range is 820 to 885 ° C. This heat treatment may be performed after the drawing process, that is, in the state of the wire material, but it is preferable to perform the heat treatment after forming the wire material into a magnet coil or the like because cracks and the like are less likely to occur.

[0010]

In the method of the present invention, the ceramic superconductor is
Since the metal coating layer is continuously alloyed and strengthened in the longitudinal direction, it is difficult to deform by bending or the like, and the superconductor layer is not damaged during handling. Further, in the method of the present invention, since alloying is performed in the final step, the drawing process of the composite billet is facilitated, and a predetermined portion in the circumferential direction of the metal coating layer is locally alloyed, so that a large coating layer is formed. The part is in a pure metal state with good electrical and thermal conductivity, and the resulting high-strength ceramic superconductor maintains good quench resistance.

[0011]

EXAMPLES The present invention will be described in detail below with reference to examples. Example _{1 Bi 2 O 3, SrCO 3} , CaCO 3, of CuO or the like primary raw material powder of each Bi: Sr: Ca: 2 in Cu atomic ratio: 2: 1: 2 were mixed so that, this mixture After the powder was calcined in the air at 820 ° C. for 50 hours, the calcined body was crushed to obtain a calcined powder having an average particle size of about 5 μm. Next, this calcined powder is CIP-molded to form a bar material having an outer diameter of 18 mmφ,
A g-alloy round pipe was filled to prepare a composite billet. Next, this composite billet was swaged to form a wire having an outer diameter of 5 mm, and this wire was rolled to form a tape-shaped wire having a width of 5 mm and a thickness of 0.2 mm. Next, this wire material is heated to 850 ° C x 50 in an oxygen stream.
The ceramics superconducting body was produced by performing heat treatment for a period of time. After that, Ag of this ceramic superconducting body
An alloy zone was formed on the coating layer by the procedure described in FIG. That is, 2 m of the Al powder 4 having an average particle size of 10 μm is formed on the Ag coating layer 3 on one surface of the running ceramics superconductor 1.
It was placed continuously in a width of m. Loading amount is 1 per 1m length
It was set to g. A laser beam is applied to the placed Al powder 4 to locally rapidly heat and melt the Al powder 4 and the Ag coating layer 3 therebelow, and then solidified to form Ag-on the Ag coating layer 3. An Al alloy zone 7 was formed to manufacture a high strength ceramic superconductor. Example 2 On the Ag coating layers on both surfaces of the ceramic superconducting body produced in Example 1, Ag-was carried out by the same method as in Example 1.
An Al alloy zone was formed.

Example 3 Bi ₂ O ₃ , PbO, SrCO ₃ , CaCO ₃ , CuO
Primary raw material powders such as Bi: Pb: Sr: Ca:
Cu was mixed so that the atomic ratio was 1.6: 0.4: 2: 2: 3, and the mixed powder was calcined in the air at 800 ° C. for 50 hours, and then the calcined body was crushed. Average particle size is about 5
It was calcined powder of μm. Next, the calcined powder was CIP-molded to form a bar material having an outer diameter of 18 mmφ
A composite billet was produced by filling a round pipe made of Ag alloy having a diameter of mmφ and an inner diameter of 18 mmφ. Next, this composite billet was swaged to form a bar with an outer diameter of 5 mmφ, and this bar was rolled to have a width of 5 mm and a thickness of 0.2 mm.
No tape-shaped wire material of
A ceramic superconducting body was produced by heat treatment at 0 ° C. for 50 hours. Then, in the same manner as in Example 1, an Ag-Ni alloy zone was formed on the Ag coating layer of this ceramic superconductor. That is, a lump Ni powder having an average particle diameter of 100 μm was continuously placed in a width of 2 mm on the Ag coating layer on one surface of the running ceramics superconductor. The loading amount was 2 g per 1 m in length. A laser beam is applied to the placed Ni powder to locally rapidly heat and melt the Ni powder and the Ag coating layer under the Ni powder, and then solidified to form Ag-Ni on one surface of the ceramic superconducting body.
An alloy layer was formed to manufacture a high strength ceramic superconductor. For each of the high-strength ceramic superconductors thus obtained and the ceramic superconductor obtained by applying a tensile load of 1 kg to the superconductor, the critical current density (Jc ) Was measured. For comparison, the same measurement was performed on the ceramic superconductor before forming the alloy layer on the coating layer of the ceramic superconductor. The results are shown in Table 1. In addition, on the Ag coating layer of the obtained high-strength ceramic superconductor, the width of the cross section is 2.3 to 2.6 mm, and the depth is 0.08 to.
An alloy layer was formed in a region of 0.11 mm with a substantially uniform concentration.

[0013]

[Table 1]

As is clear from Table 1, in the method products of the present invention (Nos. 1 to 3), the decrease in Jc was slight after forming the alloy zone and after stretching. The one in which the Al-Ni alloy zone was formed only on one side (No. 1) was Jc by the alloy zone formation.
The amount of decrease in Jc was slight, but the amount of decrease in Jc due to pulling was slightly increased. The alloy zone formed on both sides (No. 2) showed a large decrease in Jc due to the formation of the alloy zone, but a small decrease due to tension. No. In No. 3, the alloy zone was formed only on one surface, but the amount of decrease due to the tensile was small. It is considered that this is because the strength of the Al-Ni alloy layer is particularly high. On the other hand, the comparative examples (Nos. 4 and 5) had a large decrease in Jc due to the tension. This is because the alloy zone was not formed in the ceramic superconductor, and thus the ceramic superconductor layer was cracked by the tension. In addition, Ag-1% is added to the metal material of the metal pipe filled with the raw material.
A ceramic superconducting body was produced by the same method as in Example 1 except that an Al alloy was used, and the same measurement as in Example 1 was carried out. Jc before and after tensile was 18300 and
It was 18250 A / cm ² which was slightly lower than the product of the method of the present invention (Nos. 1 and 2), and the number of times of annealing during the stretching of the composite billet had to be increased by about 2 times as compared with the method of the present invention. Also, the product of the method of the present invention was used as a conductor of a magnet coil, but it was found that it could be sufficiently used without being deformed by the electromagnetic force applied to the magnet. Although the ceramic superconductor having one ceramic superconductor layer has been described in the above embodiments, it is needless to say that the same effect can be obtained by applying the method of the present invention to a multilayer or multi-core ceramic superconductor.

[0015]

As described above, according to the method of the present invention, it is possible to easily manufacture a high-strength ceramic superconducting body having excellent superconducting properties, and to exert a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing an embodiment of the method of the present invention.

[Explanation of symbols]

 1 ceramics superconductor 2 ceramics superconductor layer 3 Ag coating layer 4 metal powder 5 powder feeder 6 laser beam heater 7 alloy zone

Claims (1)

[Claims] 1. A powder or fine wire of a metal alloyable with the coating metal is linearly formed in the longitudinal direction on the metal coating layer of the ceramic superconductor having a structure in which a desired number of ceramic superconductor layers are collectively coated with a metal material. Of the high-strength ceramic superconductor characterized in that the metal powder or fine wire on the metal coating layer is locally heated to form a high-strength alloy zone continuous in the longitudinal direction in the metal coating layer. Production method.