JPH01144525A - Manufacture of ceramic-based superconductive wire - Google Patents

Abstract

PURPOSE:To obtain a wire material of excellent flexibility and stability by covering the outer side of a ceramic fiber with a mixed solution of a ceramic superconductive material, sintering the material and covering them with a stabi lizing member of metal or alloy. CONSTITUTION:An application device 3 and a baking oven 4 are arranged between a reel out bobbin 1 wound with ceramic fiber W and a winding bobbin 2 so that the fiber W is routed via the guide reels 5-8. Then, octylic acid yttrium, octylic acid barium, and naphthenic acid copper are uniformly mixed and held in an application tub 3b for Y-Ba-Cu-O-based ceramic. The SiC-based fiber is then passed through the device 3 and the oven 4 for six times to form a primary sintered layer on the fiber W. The wire material is then heated at a high temperature for a long time to form a sintered layer, on the outer circumference of which is deposited copper by evaporation. This makes it pos sible to obtain long-sized, stabilized wire material having excellent flexibility and a high specified current density.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a superconducting wire, and particularly to a method for manufacturing a ceramic superconducting wire.

(Conventional Technology) In recent years, especially since last fall, the development of ceramic superconductors has been progressing at a rapid pace all over the world.

This superconductor is Nb1G, which has the highest conventional critical temperature.
It greatly exceeds 23K of e, and is Ba-La-Cu-
0 series ceramics (critical temperature 35K), La-8r-
Cu-0 ceramics (superconductivity starting temperature 37 or higher)
, La-Ca-Cu-0 ceramics, Y-Ba-C
In addition to u-Q ceramics (zero resistance temperature of 93K), ceramics that exhibit a critical temperature of 233 or more than 300 have been reported this year.

In this way, it is possible that ceramic superconducting materials can be used at critical temperatures higher than the liquid nitrogen temperature or at room temperature.
In this case, there is no need to use expensive liquid helium, which is extremely advantageous economically, and when used in a superconducting generator or the like, the structure is simple and the efficiency of the heat engine is improved.

However, since ceramics are hard and brittle,
Unlike the Nb-Ti and Nbz Sn superconducting wires that are currently in practical use, it cannot be bent or coiled, and overcoming this point is the first step toward practical use.

Currently, there are two methods for manufacturing wire rods: 1) A method of heat-treating amorphous tape or wire in an oxygen atmosphere; 2) A method of filling raw material powder inside a 0 alloy tube (for example, Cu-Ni alloy) and pulling both ends to produce wire or tape. 2) A method of filling a copper alloy tube with ceramics, subjecting it to heat treatment, rolling, etc., and forming it into a wire or tape shape, etc. have been proposed.

However, method (2) above requires extremely rapid cooling and can only yield extremely thin wire or thin film tape, which is problematic as a method for obtaining practical wires. It is difficult to continuously manufacture long wire rods using this method, and in method (2) above, the fixed length of the wire rod is limited by the outer diameter of the initial copper alloy tube, and the processing process is difficult. ! There is a problem with it being complicated. In this case, it is desirable that the heat treatment for producing the ceramic superconductor be performed after forming, that is, near the final wire diameter, from the perspective of improving superconducting properties, but since it is covered with a copper alloy tube, oxygen is supplied inside after forming. This is extremely difficult and practically impossible.

(Problems to be Solved by the Invention) The present invention was made to solve the above-mentioned difficulties, and it is possible to easily manufacture a long wire rod without requiring rapid cooling to make it amorphous. It is an object of the present invention to provide a method for producing a ceramic superconducting wire, which can be heat-treated in an oxidizing atmosphere in the form of a long wire, and which can produce a practical wire with a high critical current density. That purpose.

[Structure of the Invention] (Means for Solving the Problems) The method for manufacturing a ceramic superconducting wire of the present invention includes (a) adding a metal salt or a metal salt containing a constituent element of a ceramic superconducting material excluding oxygen to the outer periphery of a ceramic fiber; a step of depositing a mixed solution of the metal salt dispersed in a solvent; (b) a step of sintering the deposited material; and (c) a stable layer made of a metal or an alloy thereof on the outer periphery of the sintered layer. The method is characterized by comprising a step of covering the chemical material.

The above ceramic fiber is made of silicon carbide (SiC
) type or oxide type can be used.

These fibers are continuous filaments, with a diameter of 1000 to 1300
It has high heat resistance of ℃ or more and tensile strength of 200 to 250 ka/- or more, and its average diameter is, for example, 10 to 1
There is one as small as 3 μlφ, and of course one with a larger diameter can also be used. Examples of the former SiC fiber include Tyranno fiber (trade name of 5i-Ti-C-0 fiber manufactured by Ube Industries, Ltd.) and Nicalon (
Examples of the latter oxide fiber include SiC fiber (product name of Nippon Carbon Co., Ltd.), and examples of the latter oxide fiber include Safil (trade name of
Other Si02 fibers such as Stries PLC-ICI Al2O3 fiber (trade name) can also be used.

It is preferable that the above-mentioned fiber has a volume resistivity of 106 Ωcm or less. 4. If the volume resistivity is within the above range, when the temperature of the superconducting wire rises above the critical temperature, current will easily flow within the fiber. If the zero volume resistivity is high, the terminal voltage will rise when the temperature exceeds the critical temperature, making it difficult to break down. If the volume resistivity is small, loss will occur less, which is advantageous.

Examples of ceramic superconducting materials include YBa2
There are Cu30x (x < 14: perovskite) and those to which F, etc. are added, and in this case, the constituent elements of the superconducting material excluding oxygen are Y, Ba, and Cu.

Examples of metal salts containing the above constituent elements include fatty acids.

In addition to metal salts other than alkali salts such as resin acids and naphthenic acids, that is, metal soaps, nitrates and oxalates can also be used.

The former metal soap is either in a normal liquid state and coats the outer periphery of the ceramic fiber, or it is made of xylene.

It is uniformly dispersed in a solvent such as toluene or naphtha, and then applied. On the other hand, the latter metal salt is usually used as a mixed solution uniformly dispersed in a solvent.

The atomic ratio of each constituent element in the liquid material coated on the outer periphery of the ceramic fiber is blended so as to match the atomic ratio of the components constituting the ceramic superconducting material.

The generation of a sintered layer of ceramic superconducting material is carried out at a temperature of 700 to 100 while adjusting oxidation in an oxygen stream or under oxygen pressure.
The properties are improved by heating to 0°C.

A stabilizing material is coated on the outside of this sintered layer, and as this stabilizing material, for example, silver, copper, aluminum, or an alloy thereof is plated or vapor-deposited in a concentration of, for example, 0.1 to 1.
It can be applied to a thickness of 0 μm, and an insulating coating is usually applied on the outside. Organic or inorganic materials are used as the insulating coating, and the former organic insulating coating includes UV-curable urethane resin and PVF enamel, while the latter inorganic insulating coating includes alumina, polyborosiloxane resin, and the like.

(Function) In the method of the present invention, a metal salt containing constituent elements of the ceramic superconducting material excluding oxygen or a mixed solution of such metal salts is deposited on the outside of the ceramic fiber, and then sintered. It is possible to easily produce long wire rods, and since the fiber is made of ceramics, the difference in thermal expansion with the superconducting material is small, and the adhesion is also good.

That is, by achieving the above-mentioned good adhesion and eliminating the need for processing ceramics, it is possible to manufacture long wire rods. Further, by using a liquid metal salt or a mixed solution containing a metal salt, a method similar to the manufacturing process of enamelled wire can be adopted.

(Example) Examples of the present invention will be described below.

The figure schematically shows an apparatus for manufacturing a ceramic superconducting wire according to the present invention, in which a coating device 3 and a baking furnace 4 are installed between a delivery bobbin 1 on which ceramic fiber W is wound and a winding bobbin 2. The fibers W pass through the coating device 3 and the baking furnace 4 a predetermined number of times via the guide reels 5 to 8, so that the liquid metal salt or metal contained in the coating tank 3b is coated via the coating roll 3a. A mixed solution containing salt is applied and baked in multiple layers.

Note that 9 is a drawing die.

Example 1 100g of yttrium octylate (Y content 8wt%).

Barium octylate (Ba content 8wt%) 310 (l) and copper naphthenate (Cu content 5wt%) 3429 were uniformly mixed and housed in the coating tank 3b.The ceramic fiber W was a SiC fiber (Nicalon; Nippon Carbon Co., Ltd. (trade name)) was passed through the above-mentioned coating device and the baking furnace 4 with a furnace length 51 and a furnace temperature of 300 to 400°C six times to form a primary sintered layer with a thickness of 7 μm on the ceramic fiber W. The wire thus obtained was then heated at 950°C for 2 hours to form a sintered layer.The thickness of this sintered layer was 1.8 μm.The outer periphery of this sintered layer was The critical temperature (Tc) was found to be 85K by twisting together 1000 wires with copper deposited on them and measuring their properties.
, the critical current density (Jc) is (0,5~1.0) x 1
0' Aid (at77K).

In the above embodiment, a large number of these fibers were twisted together after copper was vapor-deposited, but copper may be vapor-deposited after these fibers were twisted together.

Example 2 The same ceramic fiber as in Example 1 was used, and magnesium naphthenate (M() 3
vt%) twice and baked, and then sintered at 800°C to form a magnesium oxide layer.

Superconducting wires were produced in the same manner as in Example 1 except that the sintering conditions were 900°C for 4 hours, and 1000 of these
As a result of collectively twisting books and measuring their properties, Tc = 87
, Jc = (1~2)x10'88j (at77K
)Met.

In this case, compared to Example 1, the JC increased because of Belovsky! - This is thought to be due to differences in crystal growth.

Example 3 Yttri nitrate, rum (Y(N(h) a ・XlI2
0; Y content 27 wt%), 329 g of barium nitrate (B
523 g of a(No 3 ) 2 ; Ba content 52.5 wtX) and nitric acid @ (Cu(No 3 ) 2-3
A mixed solution prepared by dissolving 6259 (H20HCu content: 26.3 wt%) in an oxalic acid aqueous solution and adjusting the pH to 7 was applied to coating tank 3b.
Between this coating tank and the baking furnace 4, a pH of 8.
A tank containing automatically adjusted dilute ammonia water was placed in No.
After precipitating a solid substance containing Y, Ba, and cu on the iC-based fiber, the baking process was repeated six times to form a film with a thickness of 7.3 μl on the fiber. 10 of these
After 00 pieces were twisted together, they were sintered at 850°C for 2 hours.

The film thickness of the sintered layer at this time was 3.1 μl''C.Furthermore, as a result of measuring the characteristics of the wire with A(+ deposited on the outside of this sintered layer), Tc = 86K, Jc = (0, 5
~1) x 10' AIcd (at77K).

[Effects of the Invention] As described above, according to the method for manufacturing a ceramic superconducting wire of the present invention, by forming a sintered layer of a ceramic superconducting material on the outside of a ceramic fiber, long mechanical and electrical It is possible to easily produce a wire rod that is stable in terms of properties, and also to obtain a superconducting wire with a high current density.

Since the superconducting wire manufactured according to the present invention has excellent flexibility, a plurality of these wires can be used to easily form an assembled wire, a stranded wire, or a braided wire, and the wire obtained in this way can be used to form a coil. After winding, it can be impregnated with enamel varnish to create a superconducting magnet.

[Brief explanation of the drawing]

The figure is a schematic diagram showing an embodiment of an apparatus used in the method of manufacturing a ceramic superconducting wire of the present invention. 3... Coating device 4... Baking furnace W... Ceramic fiber L...
...Liquid metal salt or mixed solution containing metal salt Applicant: Showa Cable and Wire Co., Ltd. Representative Patent attorney: Satoshi Suyama - (1 other person)

Claims (6)

[Claims] (1) (a) A step of coating the outer periphery of the ceramic fiber with a metal salt containing constituent elements of the ceramic superconducting material excluding oxygen or a mixed solution of the metal salt dispersed in a solvent; A method for manufacturing a ceramic superconducting wire, comprising the steps of: sintering a deposited material; and (c) coating the outer periphery of the sintered layer with a stabilizing material made of a metal or an alloy thereof. (2) The method for manufacturing a ceramic superconducting wire according to claim 1, wherein the ceramic fiber is a silicon carbide fiber or an oxide fiber. (3) The method for manufacturing a ceramic superconducting wire according to claim 1 or 2, wherein the superconducting material is a Y-Ba-Cu-O ceramic. (4) The first claim is that the metal salt is a metal soap.
A method for manufacturing a ceramic superconducting wire according to any one of Items 1 to 3. (5) The method for producing a ceramic superconducting wire according to any one of claims 1 to 3, wherein the metal salt is a nitrate or an oxalate. (6) Ceramic fiber has a volume resistivity of 10
The method for manufacturing a ceramic superconducting wire according to claim 2, wherein the ceramic superconducting wire has a resistance of ^5 Ωcm or less.