JPH03250508A - Manufacture of ceramic superconductor - Google Patents

Abstract

PURPOSE:To obtain a ceramic superconductor having a good superconducting characteristic with ease by performing rolling work of drawing processes under prescribed conditions while ultrasonic vibration is applied to a roller. CONSTITUTION:A composite material is made up by filling a metal container with raw material which is formed as desired by drawing including rolling work, and then, this wire rod is heat-treated as prescribed to get a ceramics superconductor. The then rolling work is performed while ultrasonic vibration is applied to a roller 2 by an ultrasonic vibrator 4 under such a condition that 5000t>=D (where t: thickness in mm of the wire rod before rolling, D: diameter in mm of each of rollers 2, 3) is satisfied. As a starting material, a mixture made up by mixing Bi2O3, SrCO3, CaCO3 and CuO at an atomic ratio of 2:2:1:2 is baked and ground, and thereafter, put in an Ag pipe to be swaged to make a round wire of 5mmphi; thereafter, the round wire is rolled under ultrasonic vibration to make a tape-like rod wire with a thickness of 0.1mm, and then heat treated so that a ceramics superconductor with good superconducting characteristics can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a ceramic superconductor suitable as a conductor for cables, magnets, magnetic shields, current leads, and the like.

[Conventional technology]

In recent years, ceramic superconductors such as Y-BaCu-0 series and B1-3r-Ca-Cu-0 series that exhibit superconductivity at liquid nitrogen temperatures have been discovered, and research on their practical application is progressing in various fields.

By the way, these ceramic superconductors are brittle, so in order to process them into wire rods, etc., a composite material is created by filling a metal pipe, such as Ag or Cu, which has high workability, with a raw material that can be made into a ceramic superconductor. A method is used in which the composite material is then stretched to form a wire rod of a desired shape, and then this wire rod is subjected to a predetermined heat treatment to cause the raw material to react with the superconductor.

[Problem to be solved by the invention]

However, when the above-mentioned composite material is stretched, the metal layer of the composite material and the raw material layer have significantly different deformation resistances, so that the plastic deformation is not uniform, and as shown in FIG.
As shown in the horizontal and vertical cross-sectional views, the thickness of the raw material layer 6 inside the metal layer 5 changes in a bellows shape, and the ceramic superconductor layer obtained by heat-treating this changes in density and crystal orientation. There was a problem in that the superconductivity was poor, and therefore it was impossible to obtain a product with excellent superconducting properties.

[Means and effects for solving the problem] The present invention has been developed by conducting extensive research in view of the above circumstances, and by applying ultrasonic vibration to the rolling roll during rolling under predetermined conditions, a layer of raw material material can be made uniform. It was discovered that the material could be processed to a certain thickness, and after further research, the present invention was completed.

That is, in the present invention, a metal container is filled with a raw material that can be made into a ceramic superconductor to form a composite material, and then the composite material is stretched into a wire rod in a desired shape by rolling processing, and then the wire rod is In the method of manufacturing a ceramic superconductor by subjecting the wire to a predetermined heat treatment, the rolling process of the elongating process is performed using the following formula: 5000 t≧D (where t is the thickness of the wire before rolling, and D is the rolling roll diameter mm
1 ton of ceramics characterized by rolling while applying ultrasonic vibration to the rolling roll under conditions satisfying )
This is a method for producing a series of bodies.

The present invention will be specifically explained below with reference to the drawings.

FIG. 1 is a side sectional view showing one embodiment of the method of the present invention. In the figure, reference numeral 1 indicates a wire having a thickness of t+w as a material to be rolled, 2.3 indicates a rolling roll having a diameter of D+am, and an ultrasonic vibrator 4 is attached to the side surface of the roll 2. The ultrasonic vibrator may be applied to the rolling surface of the roll, or may be applied to both the upper and lower rolls.

As mentioned above, the raw material layer 6 inside the metal layer 5 of the wire rod 1 is uniformly processed by applying ultrasonic vibration to the rolling roll during rolling. The raw material is transferred to the rolling roll 2 by the action of ultrasonic vibration.
．． This is because the vicinity of the rolling point 3 can be quantitatively and smoothly moved forward.

In addition, in the method of the present invention, the rolling conditions when applying ultrasonic vibration are limited to satisfy the following formula: 5000 t≧D (where t is the thickness of the wire before rolling, and D is the diameter of the rolling roll). The reason for this is that the diameter of the rolling roll is equal to the wire thickness t before rolling.
When the value exceeds 5000 times, the contact length l between the rolling roll and the rolling wire increases, and the internal raw material layer cannot be quantitatively moved in front of the rolling roll even if ultrasonic vibration is applied. It is for this purpose.

In addition to the various types of ceramic superconductors mentioned above being widely used as raw materials in the method of the present invention,
Intermediates until synthesized into a ceramic superconductor that reacts with a ceramic superconductor by heat-treating an oxygen-containing substance in an atmosphere, such as a mixture or coprecipitation mixture of ceramic superconductor constituent elements or an oxygen-deficient composite oxide or An alloy of the above-mentioned constituent elements can be used.

In addition, the material of the metal container filled with the above raw materials includes Ag.
, Au, Cu, Ir, Pd, PL, or their alloys, among others, Ag or Ag alloys have good oxygen permeability, so oxygen is sufficiently supplied to the ceramic superconductor during the heat treatment process, resulting in a high Jc. In addition to being able to obtain a superconductor having a high thermal conductivity, the obtained wire has excellent quench resistance and is suitable for improving the conductivity.

In the method of the present invention, methods for stretching a composite material in which a metal container is filled with a raw material include rolling,
Any method such as extrusion, drawing, swaging, forging, -axial press compression, etc. can be applied.

〔Example〕

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

B 1zoz , 5rCO= , CaC as starting materials
0=, CuO is used and mixed so that the atomic ratio of Bi:Sr:Ca:Cu is 2:l12.Then, this mixture is calcined in the atmosphere, and it is crushed and classified. Then, the calcined powder was made into a calcined powder with an outer diameter of 20 mm.
A composite billet was prepared by filling an Ag pipe with an inner diameter of 15 mm and an inner diameter of 15 mm.

Next, the above composite billet is swaged to form a round wire of 5 mφ, which is further rolled using a rolling mill with a roll diameter of 100 ann to form a plate-shaped wire rod of thickness 0.5+++a+, and then this wire rod is Tape-shaped wire rods with a thickness of 0.1 m were prepared by varying the roll diameter and the ultrasonic vibration application conditions.

The above rolling bus schedule from 0.5■ to 0.1m is 0.4.0.32.0.26.0.20.0.
160.13.0.10m.

Further, the ultrasonic vibration was applied by applying a vibrator to the bearing portion on the side surface of the rolling roll as shown in FIG.

Each of the tape-shaped wire rods thus obtained is heat-treated in the atmosphere at 845°C for 30 hours to react the raw material to a superconductor and sinter it to form a ceramic superconductor. For the body, the critical current density (Jc
) was measured by a four-probe method under a thermal magnetic field in liquid nitrogen (77K). The results are shown in Table 1. Note that J is measured using a sample with a length of over 300+am, and the voltage terminal spacing is 30
Measurements were taken over a length of 300I11 for gon.

As is clear from Table 1, products manufactured using the method of the present invention (N01-6)
The J value was high and the variation was small.

In particular, the performance improved as the number of times ultrasonic vibrations were applied was greater, and as the ultrasonic vibrations were applied to both rolls instead of just one roll.

On the other hand, the comparative method products (Nos. 7 to 11) had low J values and large variations.

°Figure 2 shows the degree of variation of the comparison method product, taking No. 7 as an example, and comparing it with the invention method product (Na 1.2). For the method product, Jc fluctuates by one order of magnitude every 30+++m.

This is because ultrasonic vibration was applied to samples 7 to 10, but the relationship between wire thickness t and roll diameter in the final rolling bath did not satisfy the rolling conditions of the method of the present invention. This is because the internal superconductor layer was not processed uniformly because no ultrasonic vibration was applied at all, and the density and crystal orientation were significantly reduced in some places. When the structure of the comparison method product was observed, it was confirmed that the ceramic superconductor layer had changed into a bellows-like shape as shown in FIG.

〔effect〕

As described above, according to the method of the present invention, a ceramic superconductor having excellent superconducting properties such as Jc can be easily manufactured, and it has a remarkable industrial effect.

[Brief explanation of drawings]

FIG. 1 is a side sectional explanatory view showing one aspect of the rolling process of the method of the present invention, FIG. 2 is a diagram showing the state of variation in Jc of ceramic superconductors produced in Examples, and FIG. The two figures are lateral and joint cross-sectional views, respectively, of a conventional ceramic superconductor. ■...Wire rod, 2.3...Rolling roll, 4...
Ultrasonic vibrator, 5... Metal layer, 6... Raw material layer.

Claims (1)

[Claims] A metal container is filled with a raw material that can be used as a ceramic superconductor to make a composite material, and then the composite material is stretched into a wire rod of a desired shape by rolling processing, and then the wire rod is subjected to a predetermined heat treatment. In the method for manufacturing a ceramic superconductor, the rolling process of the elongation process is performed according to the following formula: 5000t≧D (where t is the wire thickness before rolling, mm, and D is the diameter of the rolling roll, mm.) 1. A method for manufacturing a ceramic superconductor, the method comprising rolling a ceramic superconductor while applying ultrasonic vibration to a rolling roll under conditions that satisfy the following.