JPH01144523A - Manufacture of ceramic-base superconductive wire - Google Patents

Abstract

PURPOSE:To obtain a long-sized stabilized wire of excellent flexibility by covering the outer side of a ceramic fiber with ceramic superconductive material and heating and sintering the material in an oxidizing atmosphere so that the outer circumference of the fiber is covered with the stabilized ceramic material. CONSTITUTION:A silicon carbide-based ceramic fiber 4 is passed through a heated melting crucible 1 to cause molten YBa2Cu3 alloy a adhere to the outer circumference of the fiber. While the fiber 4 runs over a guide reel 5 and passes through an insert B, a specified thickness of molten liquid 3 is applied over the outer circumference of the fiber by means of a die. Then they are heated in an oxidizing atmosphere to form a sintered layer of a superconductive material. Further on the outer circumference of the sintered layer is formed by sputtering, a conductive ceramic of TiC which is to become a stabilizing layer, over which is further formed a baked layer of organic insulation paint. This makes it possible to easily manufacture long-sized, stabilized wire material having excellent flexibility.

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 Nb3G, which has the highest conventional critical temperature.
It is much more than 23 of e, and it is Ba-La-Cu-
0 series ceramics (critical temperature 35), La-3r-
Cu-0 ceramics (superconductivity starting temperature 37 or higher)
, La-Ca-Cu-0 ceramics, Y-Ba-C
In addition to u-0 series ceramics (zero resistance temperature of 93), ceramics that exhibit critical temperatures of 233 or 300 or more 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 Nb3Sn 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 of manufacturing wire rods: (1) A method of heat-treating amorphous tape or wire in an oxygen atmosphere; (2) Filling raw material powder inside a 0 alloy tube (for example, Cu-Ni alloy) and pulling both ends to create edge material or The following methods have been proposed: (1) Filling a copper-based alloy tube with ceramics, subjecting it to heat treatment, rolling, etc., and forming it into a wire or tape shape.

However, the above method (■) requires extremely rapid cooling and can only yield extremely thin wire rods or thin film tapes, so it has disadvantages as a method for obtaining practical wire rods. However, it is difficult to continuously manufacture long wire rods, and in method (■) 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 complicated. . In this case, the heat treatment for producing the ceramic superconductor is performed after molding from the viewpoint of improving superconducting properties.
In other words, it is desirable to apply this near the final diameter of the wire, but since it is covered with a copper-based alloy tube, it is extremely difficult to supply oxygen to the inside after forming, which is 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.

[Configuration of the Invention (Means for Solving Problems) The method for manufacturing a ceramic superconducting wire of the present invention includes (a) applying a ceramic superconducting material to the outer periphery of a ceramic fiber or heating it in an oxidizing atmosphere; (b) Next, sintering the deposited material; (c) Adding a stabilizing material made of conductive ceramics or conductive polymer material to the outer periphery of the sintered layer. It is characterized by consisting of a step of covering the.

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 250kl)/- or more, and its average diameter is, for example, 10 to
There is one as extremely small as 13 μlφ, but of course one with a larger diameter can also be used. Examples of the former SiC fiber include Tyrano 111 fiber (5i-Ti-C-0 fiber trade name manufactured by Ube Industries, Ltd.) and Nicalon (SiC fiber trade name manufactured by Nippon Carbon Co., Ltd.). The latter oxide fiber is manufactured by Safil (Imperial Cheiical Co., Ltd., UK).
In addition to Industries PLC-ICI AI201 fiber (trade name), 5102 series fiber can be used.

The above fiber has a volume resistivity of 10' QCra
This is because if the zero volume resistivity, which is preferably below, is within the above range, when the temperature of the superconducting wire rises above the critical temperature, current will easily flow within the fiber and it will be difficult to break. If the volume resistivity is high, the terminal voltage will rise when the temperature exceeds the critical temperature, making it easy to break down.If the zero volume resistivity is small, loss will occur less, which is advantageous.

Examples of superconducting materials deposited on the outer periphery of the fiber include yaa 2 Cu ox (x < 14: perovskite) and materials to which F or the like is added.
Examples of constituent materials that produce ceramic superconducting materials by heat treatment in an oxidizing atmosphere include Y-Ba-C.
U-based alloys (Y:Ba:Cu = 1:2:3, atomic ratio) and mixed powders of Y, Ba, Cu, or their oxides, carbonates, etc. are used, and ceramic fibers are added to the melt. By immersing the material, it is coated on the outer periphery to a thickness of, for example, about 0.1 to 20 μm. Of course, other ceramic-based superconducting materials and constituent materials for producing them can also be used.

In addition to the above-mentioned deposition from the melt state, it is also possible to deposit from the gas phase or ionic state. Examples of such methods include plasma discharge, vapor deposition, thermal spraying, and sputtering.

The generation of a sintered layer of ceramic superconducting material is carried out at a temperature of 700 to 100 mm 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, conductive ceramics or conductive polymer materials are used. The former conductive ceramics include T
iC, NbC, WC, TaC, ZrB, BN, ZrN
Examples of the latter conductive polymer materials include polyacetylene and polypyrrole. It is preferable that these stabilizing materials have a volume resistivity of 105 Ωcm or less. The reason for this is the same as that for ceramic fibers, but especially when conductive ceramics are used, thermal expansion of the wire components can be avoided. The difference can be made small, which is extremely advantageous against thermal effects.

The stabilizing material coating can be applied in the melt, gas phase or ionic state, similar to the application of the superconducting material. An insulating coating is usually applied to the outside of the above-mentioned stabilizing material. Organic or inorganic materials are used as the insulating coating, and the former organic insulating coating includes UV curing urethane resin and PVF enamel.
On the other hand, examples of the latter inorganic insulating coating include alumina and polyborosiloxane resin.

(Function) In the method of the present invention, a ceramic superconducting material or a constituent material that generates it by heating in an oxidizing atmosphere is deposited on the outside of the ceramic fiber and then sintered. It can be easily manufactured, and since the fiber is made of ceramic, the difference in thermal expansion with the superconducting material is small, and the adhesion is 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.

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

Example 1 A SiC ceramic fiber (Tyranno fiber; 5i-Ti-C-0 fiber trade name manufactured by Ube Industries, Ltd.) with an outer diameter of 12μ■φ was placed in a melting crucible made of platinum or quartz as shown in Fig. 3. 1, and YBa2 on the outer periphery.
Deposit Cu and alloy. This crucible 1 is heated by an external heater 2, and the YBa2Cu
i Alloy 3 is maintained in a molten state.

The thickness of the adhered layer is 5 to 6 μm.

The ceramic fiber 4 is passed through the crucible through a hole in an insert 6 disposed at the bottom of the crucible 1 via a lower guide reel 5, and a die 7 covers the outer periphery of the crucible with a predetermined thickness of melt. It will be worn. The insert 6 and the die 7 are made of NO, Ni-Cr, -Al alloy, or the like.

Then 2 kgf/c (700 to io
o.

℃ to form a sintered layer of ceramic superconducting material. This sintering step can also be carried out continuously following the above-described deposition step.

After sintering, a conductive ceramic such as ID is applied to the outer periphery of the sintered wire by sputtering, and finally, a coated and baked layer of an organic insulating paint, such as formal varnish, is formed on the outside of this stabilizing layer.

The conductive ceramic layer described above is provided for the purpose of functioning as a stabilizing material and for mechanical protection.

As shown in FIG. 1, the ceramic superconductor m10 manufactured in this manner has a structure in which a sintered layer 12, a stabilizing layer 13, and an insulating layer 14 of a ceramic superconducting material are sequentially formed around the outer periphery of a ceramic fiber 11. .

Example 2 YBa2 Cut was applied to the outer periphery of a SiC fiber (Nicalon; trade name manufactured by Nippon Carbon Co., Ltd.) with an outer diameter of 10 μmφ.
A ceramic consisting of Ox (x < 14) was coated to a thickness of 5 to 6 μm by sputtering, then heated in an oxidizing atmosphere at 950°C to sinter the ceramic, and then TiC was vapor-deposited on the outer periphery of the ceramic. did. FIG. 2 shows the results of measuring the critical temperature (Tc) of a bundle of 1000 wires thus obtained.

Furthermore, the result of measuring the critical current density (Jc) of the above-mentioned collective line shows that Jc=2000^/d (77K).

[Effects of the Invention] As described above, according to the method for manufacturing a ceramic superconducting wire of the present invention, a sintered layer of a ceramic superconducting material and a stabilizing material made of a ceramic or polymeric material are sequentially formed on the outside of a ceramic fiber. By doing so,
A long mechanically and electrically stable wire rod can be easily produced, and 1. A superconducting wire with high current density can be obtained.

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]

FIG. 1 is a sectional view showing an example of a ceramic superconducting wire manufactured by the method of the present invention, FIG. 2 is a graph showing its critical temperature, and FIG. 3 is a schematic diagram of its manufacturing apparatus. 1...... Melting crucible 3... YBa 2 Cu1 alloy liquid 4.
11...Ceramic fiber 7...Dice 10...Ceramic superconducting wire 12...
...... Ceramic superconducting material sintered layer 13.
・・・・・・Stabilizing layer 14・・・・・・・・・Insulating layer Applicant Showa Cable and Wire Co., Ltd. Representative Patent attorney Sa Suyama - (1 other person) Figure 11 Temperature TLKI Figure 2

Claims (7)

[Claims] (1) (a) A step of depositing a ceramic superconducting material or a constituent material that generates it by heating in an oxidizing atmosphere on the outer periphery of the ceramic fiber, and (b) A step of sintering the deposited material. and (c) coating the outer periphery of the sintered layer with a stabilizing material made of conductive ceramics or conductive polymer material. (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) 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. (4) The stabilizing material made of conductive ceramics or conductive polymer material has a volume resistivity of 10^5 Ωcm.
A method for manufacturing a ceramic superconducting wire according to claim 1 or 2 below. (5) The method for manufacturing a ceramic superconducting wire according to any one of claims 1 to 4, wherein the superconducting substance is a Y-Ba-Cu-O ceramic. (6) A method for manufacturing a ceramic superconducting wire according to any one of claims 1 to 5, wherein the superconducting material or its constituent materials are deposited in a molten state. (7) A method for producing a ceramic superconducting wire according to any one of claims 1 to 5, wherein the superconducting material or its constituent materials are deposited in a gas phase or an ionic state.