JPS63307620A - Manufacture of superconductive conductor - Google Patents

Abstract

PURPOSE:To manufacture a long superconductive conductor of oxide type with high critical temp. easily with simple processes, by coating a specific paste on a base, and subjecting it to heat treatment. CONSTITUTION:Either hydrophilic or hydro-pholic binder is mixed with at least either a raw material powder of a superconductive material of oxide type or a powder superconductive material of oxide type, to provide a substrate in the form of paste 3. This paste substance 3 is coated on a base 4, which is subjected to heat treatment. This base 4 is in the form of tape, wire, filament, fiber or strip made of either metal or non-metal. This enables simple and easy manufacture of long superconductive conductor with high critical temp.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for manufacturing a superconducting conductor used in superconducting equipment such as magnets for nuclear magnetic resonance apparatuses and magnets for particle accelerators.

"Prior Art" Recently, various oxide-based superconducting materials have been developed as new superconducting materials different from conventional intermetallic compound-based superconducting materials and alloy-based superconducting materials. This type of superconducting material has an extremely high critical temperature (Tc) at which it transitions from a normal conductive state to a superconducting state, and can maintain its superconducting state by cooling with liquid nitrogen, so it has a variety of applications. A lot of research and development is being carried out.

Conventionally, as a method for manufacturing superconducting wires using this type of superconducting material, oxide-based superconducting material powder or superconducting material is placed inside a metal pipe made of copper, silver, platinum, gold, stainless steel, etc. A method is known in which the material is filled with raw material powder and then subjected to diameter reduction processing and heat treatment as necessary.

"Problems to be Solved by the Invention" By the way, the oxide-based superconducting materials mentioned above are extremely brittle and have poor workability, so in the process of filling the metal pipe with powder to reduce its diameter, However, in order to prevent internal defects such as cracks, it is necessary to carefully consider the processing rate, annealing conditions, heating temperature, etc., and the process becomes complicated. In addition, in a superconducting wire manufactured by generating a superconductor inside a metal pipe, current flows mainly around the outer peripheral surface of the superconductor.
Since no current tends to flow through the superconductor at the center, there is a problem in that the superconducting material at the center is wasted.

This invention □ was made in view of the above-mentioned problems, and aims to provide a method for easily producing a long oxide-based superconducting conductor having an extremely high critical temperature through simple steps.

"Means for Solving the Problems" The method for producing a superconducting conductor of the present invention includes adding a hydrophilic binder or a hydrophobic raw binder to at least one of the raw material powder of the oxide superconducting material and the powder of the oxide superconducting material. A paste-like substance is prepared by mixing the above, and then this paste-like substance is applied to a base material, and furthermore, this base material is subjected to heat treatment.

Here, the base material is a tape, wire, filament, fiber, strip, etc. made of metal or non-metal.

"Example" Hereinafter, an example in which the present invention is applied to a method for manufacturing a Y-B a-Cu-0 based superconducting wire will be described.

In order to manufacture a Y-B a-Cu-0 based superconducting conductor by carrying out the method of the present invention, first, Y, 0. Powder and BaCO
4 powder and CuO powder as Y:Ba:Cu=1:2
: Mix at a ratio of 3:3 and bake. This firing is performed under conditions of heating at 900-1000°C for 1-24 hours, but if necessary, heating at 500-1000°C may be performed before this heat treatment.
Temporary baking may be performed by heating at 1 to 24 hours.

Next, the fired body is ground in a grinding device such as a mortar or a ball mill to obtain powder.

Next, one or more binders selected from the hydrophilic binders shown below or one or more binders selected from the hydrophobic binders shown below are mixed into the powder. to create a paste-like substance.

The hydrophilic binders mixed here are starch, combustible starch, α
A water-soluble or water-swellable binder such as starch, dextrin, alginic acid, sodium alginate, gum arabic, gum tragacanth, gum gatchi, casein, casein soda, glucose, gelatin, impure gelatin, wheat flour, soybean protein, hepton, molasses, Na-carboxymethylcellulose, methylcellulose, -s, methylethylcellulose, cellulose acetate, sodium lignin sulfonate,
A water-soluble or water-swollen binder such as calcium lignin sulfonate, Na-carboxymethyl starch, hydroxyethyl starch, starch phosphate sodium, glycerin, pulp waste liquid, polyvinyl alcohol, polyvinyl methyl ether, and sodium polyacrylate; These include solvent-soluble and water-soluble organic compounds such as hydroxypropylcellulose, hydroxypropylmethylcellulose, polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, vinylpyrrolidone-vinyl acetate copolymer, tannic acid, and urea. In addition, hydrophobic binders include natural products such as shalac, rosin emulsion, animal and vegetable oils, liquid paraffin, wax emulsions (carnauba wax, carbo wax, ground wax, etc.), ceresin, heavy oil, machine oil, spindle oil, etc. These include ethyl cellulose, acetyl cellulose, ester gum, polyvinyl acetate, chroman resin, petroleum resin, phenolic resin, and ethyl silicate.

Next, the paste-like substance is applied to a tape made of a normal conductor by brushing, spraying, or the like. After this coating operation is completed, the normal conductor and the pasty substance are heated at 900 to 1000°C for 1 to 24 hours to sinter. At this time, the binder disappears due to heat and only the superconducting layer remains on the normal conductor, making it possible to obtain a tape-shaped superconducting conductor.

If a superconducting conductor is manufactured through the above steps, the superconducting conductor can be easily manufactured without filling a metal pipe with powder or performing diameter reduction processing. Further, by adjusting the thickness of the paste material applied to the normal conductor, a superconducting conductor having an α superconducting layer having a desired thickness can be manufactured.

According to the method explained above, it is possible to continuously produce a long tape-shaped superconducting conductor, and the obtained superconducting tape exhibits an extremely high critical temperature, which is higher than the conventional cooling conditions for superconductors. It can be used under extremely advantageous conditions. A superconducting magnet can be obtained by winding this superconducting tape around a winding drum, thereby simplifying the cooling equipment attached to the superconducting magnet, and
A superconducting magnet with low operating cost can be created.

On the other hand, FIG. 1 shows an example of a coating device used in the manufacturing method of the present invention.

This coating device is composed of a container 1 and a coating device 2 disposed inside this container 1.

The container 1 is a container with an inclined side surface and a widened opening, and stores the paste-like substance 3 therein.

A coating device 2 is arranged inside this container l. This coating device 2 has a stainless steel tape 4 (
a roller 5 that pulls in the base material), and a roller 6 that sends out the stainless steel tape 4 drawn into the roller 5 to the outside of the container 1.
It consists of.

When manufacturing a superconducting conductor using a manufacturing apparatus having such a configuration, a paste-like substance 3 similar to the above-mentioned paste-like substance is filled into a container l as shown in FIG. After doing this, the coating device 2 is operated to rotate the rollers 5 and 6. In this way, roller 5
pulls the stainless steel tape 4 into the container i and passes it through the paste-like substance 3, and then the roller 6 sends the stainless steel tape 4 out of the container l. In this case, the drawing speed and feeding speed of the stainless steel tape 4 are l
It is preferably 0 cI/min to 500 cm/min or less, and the passage time for the stainless steel tape 4 to pass through the paste material 3 is preferably about 30 seconds to 600 seconds.

Then, if necessary, the stainless steel tape 4 is passed through the pasty substance 3 as described above one or more times, so that the surface of the stainless steel tape 4 is coated with the paste substance 3 to a thickness of 1 μm. ~500μ! Laminate the following thin films. After this, the stainless steel tape 4 is heated at a relatively low temperature to decompose and eliminate the binder from the paste material 3 applied to its surface.

After this, apply this stainless steel tape 4 to 800~11
Heat treatment is performed at 00° C. for about 1 to 100 hours. This heat treatment is performed in an oxidizing atmosphere such as the air, and optionally in an oxygen atmosphere. In this way,
Y oxide, Ba oxide, and copper oxide on the surface of this stainless steel tape 4 react, and a superconducting oxide is generated on this surface.

By carrying out the method described above, a long superconducting conductor can be obtained, and the same effects as in the embodiments described above can be obtained.

In addition, in this method for manufacturing a superconducting conductor, raw material powder of oxide-based superconducting material is mixed with the binder, but oxide-based superconducting material powder may also be mixed. A mixture of superconducting material powder and raw material powder of oxide-based superconducting material may be mixed.

Furthermore, in this superconducting conductor manufacturing method, the stainless steel tape 4 is used as the base material, but a metal material other than stainless steel or a non-metallic material such as glass fiber may also be used, and the shape may be a tape, wire, It may be filament, fiber, or strip.

"Effects of the Invention" According to the method for producing a superconducting conductor of the present invention, at least one of the raw material powder of the oxide-based superconducting material and the oxide-based superconducting material powder is mixed with a hydrophilic or hydrophobic binder. A superconducting conductor is formed by creating a paste-like material, then applying this paste-like material to a base material, and then subjecting this base material to heat treatment. Conductors can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a coating device used in the manufacturing method of the present invention. 3...Paste-like substance, 4...Base material (stainless steel tape).

Claims (1)

[Claims] A paste-like substance is created by mixing a hydrophilic binder or a hydrophobic binder with at least one of the raw material powder of the oxide-based superconducting material and the oxide-based superconducting material powder, and then this paste-like substance is used as a base material. 1. A method for producing a superconducting conductor, which comprises coating the base material, and then subjecting the base material to heat treatment.