JPH01616A - Manufacturing method of ceramic superconducting wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a ceramic superconducting wire in which a ceramic superconductor is fixed to a core material.

[Conventional technology and its problems]

Recently, Y-Ba-Cu-0 system with high critical temperature number, L
a-3r-Cu-0 system, Y-3r-Cu-O system, 5c-
Ceramic superconductors such as Ba-Cu-0 are attracting attention, but these cannot be plastically worked like metal materials, and in order to process them into wire rods, for example, raw material powder must be mixed with Ag.
Attempts have been made to press fit the material into a pipe, draw it out, and then heat and sinter it, or to grow a film using a PVD method such as sputtering. However, the former method has limitations in thin wire processing and high-speed wire drawing, resulting in poor productivity, while the latter method not only has low film formation speed and poor productivity, but also It is unsuitable for manufacturing long items because it warps during work. - For this reason, the development of wire processing methods has become one of the important issues in the practical application of ceramic superconductors.

[Means for solving problems]

The present invention was made in view of the above circumstances, and its purpose is to provide a method for efficiently manufacturing a long ceramic superconducting wire having excellent superconducting properties, excellent formability such as coil winding, and mechanical strength. It's about doing.

That is, the first aspect of the present invention is to continuously pass a linear core material made of a heat-resistant substance through a liquid dispersion in which superconductor powder or raw material powder that becomes a superconductor by heat treatment is dispersed in a liquid agent. After performing a desired number of steps of sequentially applying superconductor powder or its raw material powder onto the core material and preheating the adhered body to remove the liquid agent by evaporation and decomposition, heat treatment is performed. sintering of the attached superconductor powder, or a step of reacting and sintering the raw material powder to the superconductor and fixing it to the core material, and then adjusting the chemical composition and crystal structure of the superconductor by annealing. It is characterized by the following.

Further, the second invention of the present invention provides that a linear core material made of a heat-resistant substance is continuously passed through a dispersion liquid in which superconductor powder or raw material powder that becomes a superconductor by heat treatment is dispersed in a solvent, A step of adhering superconductor powder or its raw material powder onto the core material, a step of preheating the adhering body to remove the solvent by evaporation and decomposition, and applying a heat treatment to the adhering body from which the solvent has been removed to adhere it. A process of sintering the superconductor powder or reacting and sintering the raw material powder with the superconductor to fix it to the core material, and a process of depositing a non-superconductor substance on the superconductor fixed to the core material. This method of manufacturing a ceramic superconductor material is characterized in that after a desired number of sequential steps are performed, a step of adjusting the chemical composition and crystal structure of the superconductor by annealing treatment is further performed.

In the above, the superconductor powder is, for example, YlBat.
CusOt-δ (δ#0.2), Y I S r t
Cu 5O7-δ, Y, 5rtcu307-δ, (Y
SDy) BaCu30t-δ, etc., and the raw material powder that becomes a superconductor through heat treatment is YzOx+Cu
O+13acos and Laz03 +CuO+5rCOt
This mixed powder has a powder content of 700 to 1100.
By heat treatment at °C, the above Y 1 B a z Cu
30 t-δ or Y b S r 2 Cu z O7
-δ becomes a superconductor.

Water, ethyl alcohol, butyl carbinol, propylene glycol, ethylene glycol, hexylene glycol, diethylene glycol, etc. are used as the liquid agent. The superconductor powder or its raw material powder used in the present invention is usually a particle insoluble in the above-mentioned solvent, and its particle size is 30I! m or less, preferably 0.001-1 OjIt
The concentration in the dispersion liquid is 25 wt% or more (hereinafter abbreviated as %), preferably 40 to 90%.

The raw material powder described above may be soluble in the liquid agent, such as Cu (NOz)z, B a (NOx
)t, Y(N0s)z, Cu (CH3COri2
Alkoxy compounds, acetanilide compounds, etc. are also used.

Core materials include stainless steel, Ni and Ni alloys, W, M
o, Metal materials such as Ag, Fe and Fe alloys, Cu and Cu alloys, Al2O5, Zr01, C, glass,
Inorganic materials such as SiO and %SiC are used.

The dispersion liquid is attached to the core material, and when a thickener and/or dispersant is added to this dispersion liquid, the dispersibility of the superconducting powder or its raw material powder is improved, and the dispersion of the superconducting powder or its raw material powder is improved. The amount of adhesion increases. Methyl cellulose, polyvinyl alcohol, water glass, etc. are used as the thickener. Further, as a dispersant, a polyoxyethylene adduct or the like is used. The thickness of the dispersion liquid adhering to the core material is 1'O
The OJ should be 1ml or less, usually about 1 to 50μ. The amount of adhesion can be adjusted by using a drawing die in addition to the viscosity of the dispersion and the immersion time in the dispersion. However, if the core material vibrates or it is difficult to align the drawing die and the core material, uneven thickness will occur, so the use of the drawing die may be discontinued.

Uneven thickness of the superconductor layer can be prevented by reducing the thickness of the superconducting powder or its raw material powder each time it is deposited using a drawing die, subjecting it to preheating treatment, and sequentially repeating this process.

According to this method, an additional advantage is that a dense and thick structure can be obtained.

In the preheating treatment performed after the dispersion is applied to the core material, at least a part of the solution is removed by evaporation or decomposition, but the thickener or dispersant is also removed in the same way. In the heat treatment, the raw material powder reacts with the superconductor powder, and the superconductor powder is further sintered. In the final annealing treatment, the chemical composition or crystal structure of the superconductor is adjusted.

The core material is a wire or tape with a radius or thickness of 150 μ or less, preferably 10 to 100 −, but the reason for this limitation is that if the radius or thickness is less than 10 μ, the strength and electrothermal properties will decrease;
When it exceeds 1100p, flexibility and bendability deteriorate. Further, when the thickness of the superconductor layer covering this core material is 5 to 50% of the radius or thickness of the core material, both mechanical and electrical conditions can be satisfied as a superconducting wire material. That is, since the ceramic superconductor described above is hard and brittle, its coating thickness is 50% of the radius or thickness of the core material.
If it exceeds 5%, cracks will occur during bending such as coil winding, and if it is less than 5%, sufficient current capacity will not be obtained.
The economic value as a superconducting wire material will be drastically reduced.

A cross section of a ceramic superconducting wire obtained by the present invention is illustrated in FIG. That is, A in the figure shows a core material a having a circular cross section.
Figure 1 shows an example in which a superconductor layer b1 is fixed to a core material a2 having a rectangular cross section. In this sectional view showing an example, superconductor layers are formed in three layers b3, b4, and b5 around a core material a3 having a circular cross section.

By the way, ceramic superconductors such as Y-Ba-Cu-0 have high reactivity, so carbon fiber or S is used as the core material.
When an iC fiber is used, a part of the superconductor is reduced, and the critical temperature (hereinafter abbreviated as Tc) and critical current density (hereinafter abbreviated as J) are reduced. In such a case, MgO1A1. A low-reactivity substance such as O, ZrO, etc. is coated to suppress the reaction between the core material and the superconductor.

Figure 1 is a sectional view showing an example of this, in which a barrier d1 is coated around a core material aμm and a superconductor J5b6 is fixed thereon. The thickness of the barrier is usually 0. O1~1
Especially useful is 0.5 to 5-. If the barrier is too thick, the flexibility and deformability of the ceramic superconducting wire will be impaired.

The second invention is to coat and/or incorporate a non-superconducting substance on the superconductor layer of the wire produced by the method of the first invention, and thereby, a ceramic material such as Y-Ba-Cu-0 based The chemical composition of the system superconductor, especially 0, is stabilized, chemical influences from the outside world such as water and 5O8NO□ are blocked, and mechanical reinforcement is provided. Furthermore,
Jc is improved due to the pinning effect of the non-superconductor.

FIG. 2A is a cross-sectional view of a wire showing one example, in which a superconductor layer b7 is fixed around a core material a5, and a non-superconductor layer c1 is attached to the outer periphery of the superconductor layer b7. The opening in Figure 2 is a cross-sectional view of a wire showing another example, and superconductor layers b8, b9,
blo and non-superconducting material layers C2, C3, and C4 are alternately and repeatedly distributed in concentric circles.

The thickness of the above-mentioned non-superconducting material layer is suitably 0.001 to 54, and a thickness of about 0.005 to 1- is particularly practical, and if it is less than 0.001711+, the effect cannot be obtained. , 5-, flexibility decreases.

The above-mentioned non-superconducting materials include Cu, Cu-Ni, and W.

Mo, Ni, Aj! , metal materials such as 5b-pb, glass, glass ceramics, An! ,0. ,Cuo,
Inorganic materials such as CaOlMgOlZrOg and organic materials such as polyethylene, PVC1 fluorinated ethylene, polyimide, polyamide, and polyurethane are used.

In addition, methods for coating non-superconducting materials include PVD, C
It can also be done by methods such as VD, plating (chemical plating), and spraying.

It is also possible to deposit Mi conductor powder or its raw material powder, preheat it, coat it with a non-superconducting material, repeat this step a desired number of times, and then finally heat and anneale it all at once.

FIG. 3 is a conceptual diagram of a vertical continuous production line showing an example of an apparatus for carrying out the present invention.

A linear core material 1 such as a wire or tape is supplied from an uncoiler 2, passes through guides 3 and 4, and is introduced into a dispersion liquid tank 5 through a watertight die 6. The dispersion liquid 7 is adhered thereto, and the adhesion thickness of the dispersion liquid 7 is made constant by a squeezing die 8 attached to the outlet of the tank 5, and then the dispersion liquid 7 is sent out. The consumed dispersion liquid 7 is continuously replenished from the storage tank 9. The dispersion liquid 7 adhering to the surface of the core material 1 is heated in a preheating chamber 10,
Solvents, thickeners, additives, etc. are removed by evaporation, decomposition, and
Next, the raw material powder or superconductor powder is reacted with the superconductor and/or sintered in the sintering chamber 11, and then the chemical composition etc. are adjusted in the annealer chamber 12, and then passed through the guide 13 and wound around the recoiler 14. It will be done.

The superconducting properties of the superconducting wire obtained by the present invention are largely influenced by the heat treatment conditions. Therefore, in the heat treatment chamber 11 shown in FIG. 1, experiments must be conducted for each superconductor composition to optimize the equipment design and heating conditions. An annealing chamber is provided after the heat treatment chamber, and annealing is performed here at '/H degrees lower than the sintering temperature to adjust the chemical composition such as oxygen and the crystal structure.
Characteristics such as:

By evaporating or decomposing the liquid agent and additives in the preheating chamber 10, the effects of subsequent heat treatment and annealing treatment are improved.

〔Example〕

The present invention will be specifically explained below using examples.

Sample preparation was performed using the vertical continuous production line shown in FIG.

Example-1 A 251Mφ MO wire coated with MgO to a thickness of 0.5IIgA by a sputtering method was used as a core material, and this core material was coated with 65% Y+BazCusOy-δ powder with a particle size of L5n.
, passed through a dispersion consisting of 10% ethyl cellulose (additive) and the remainder butyl carbinol (solvent) to adhere the dispersion, passed through a 60-φ squeezing die, and heated in air at 600°C for 1 minute in a preheating chamber. The additives and liquid agent were evaporated and decomposed by heating, and then the mixture was heated in the atmosphere at 950'CI for 5 minutes in a heat treatment chamber. Thereafter, it was annealed at 720''C for 10 minutes in the air.

Example 2 Using the same core material and dispersion as in Example 1, the steps of dispersion deposition and preheating treatment were repeated three times, and then air heating was performed at 950° C. for 15 minutes in a sintering chamber. The diameter of the squeezing die at the outlet of the dispersion tank was set to 35, 45, and 60 μm each time. These samples were further annealed at 790''C for 5 minutes.

Example 3 A sample was prepared using the following dispersion liquid and under the same conditions as Example 2 except for the following dispersion. Dispersion liquid composition: Y2O.

16%, B a COx 37%, Cu022%, ethyl cellulose (additive) 10%, balance hexylene glycol (liquid).

Example 4 A sample was prepared under the same conditions as Example 2 except that a 50-φ carbon fiber coated with 2μ of MgO was used as the core material, and the other conditions were the same as in Example 2.

The above core material is made by uniformly adhering a mixture of 60% MgO powder with a particle size of 0.1-φ, 25% ethyl cellulose, and the balance ethyl carbinol to carbon fibers, and then heat-treating the mixture to produce ethyl cellulose and ethyl carbinol. was evaporated, decomposed and removed, and then heated at 1500 °C in an argon stream.
It was produced by heat treatment at ℃.

Example-5 Using the same core material and dispersion as in Example-4, min+lk
Liquid adhesion → Preliminary heat treatment in air for 600″CI minutes → 95
Sintering treatment in the air for 15 minutes at 0°C → Zro1 with a thickness of 1-
The svantering process was repeated three times to produce 100 mm samples. The diameter of the squeezing die at the outlet of the dispersion liquid tank was set to 35, 45, 60, and 1111 mm each time. Thereafter, annealing treatment was performed at 720° C. for 10 minutes in the air.

Example-6 Changing BaC0 in the dispersion composition to barium ethoxide,
A sample was otherwise produced under the same conditions as in Example-3.

For comparison, samples were prepared under the following conditions.

Comparative Example-1 A sample was prepared under the same conditions as Example-1 except that a 25-φ MO wire without MgO coating was used as the core material. However, no annealing treatment was performed after the sintering treatment.

Comparative Example-2 A sample was prepared using the same core material as in Comparative Example-1, with the diameter of the drawing die at the outlet of the decomposition tank being 100 μm, and under the same conditions as in Example-1. However, no annealing treatment was performed after the sintering treatment.

The sample wire rods produced in the above examples and comparative examples were wound around a 100 mφ cylinder, and 'rC and Jc
was measured by the four-terminal method. The results are summarized in Table 1.

Table 1 *Temperature at which the resistance becomes completely zero As is clear from Table 1, the products manufactured using the method of the present invention (Examples 1 to
6) has lower Tc and Jc compared to the comparison method product (Comparative Example 1.2).
Both show high values.

Among the products manufactured by the method of the present invention, those in which the superconductor layer was repeatedly coated three times and annealed (Example 2) had a higher Tc than those in which the superconductor layer was coated once (Example 1).
, Jc is shown. The one using carbon fiber coated with MgO as the core material (Example 4) also shows a high value.0 or more is an example when superconducting powder is dispersed in the dispersion liquid, but when the dispersion liquid is heated The material in which raw material powder to become a superconductor was dispersed (Example 3.6) also showed high characteristics. In particular, the superconductor layer in which the non-superconductor layer is contained and covered in a thin concentric manner (Example 5) has a high Jc value.

Compared to the product produced using the method of the present invention, the comparative method product shows lower values for both Tc and Jc, but in Comparative Example 1, there was a reaction between the core material and the superconductor layer, and in Comparative Example 2, Is the superconductor layer too thick? It is presumed that cracks occurred when it was wound around a cylinder of 00 mφ, and only low values of Tc and Jc were obtained.

Although the embodiment of the present invention has been described above using the apparatus shown in FIG. It can also be placed and used.

〔effect〕

As described above, according to the present invention, T., J.

Ceramic superconducting wires with excellent properties such as If the wires are twisted and used, it can be applied to conductors that require large currents, such as magnets and cables, and has a remarkable industrial effect.

[Brief explanation of the drawing]

Fig. 1.2 is a cross-sectional view showing an example of a ceramic superconducting wire manufactured according to the present invention, and Fig. 3 is a conceptual diagram of a vertical continuous M production line showing an example of an apparatus for carrying out the present invention. . ! , al-a6... core material, b1-blO... superconductor layer, 01-c4... non-superconducting material layer, dl...
・Barrier, 2... Uncoiler - 13, 4, 13...
・Guide, 5... Dispersion liquid tank, 6... Watertight die, 7... Dispersion liquid, 8... Squeezing die, 9...
・Storage tank, lO... Preheating chamber, 11... Heat treatment chamber, 12... Annealer chamber, 14... Recoiler.

Claims (12)

[Claims] (1) A linear core material made of a heat-resistant substance is continuously passed through a liquid dispersion in which superconductor powder or raw material powder that becomes a superconductor by heat treatment is dispersed in a liquid agent, and the core material is After performing a desired number of steps of sequentially applying a conductor powder or its raw material powder to the substrate and preheating the adhered body to remove the liquid agent by evaporation and decomposition, heat treatment is performed to cause the adhesion to take place. The superconductor powder is sintered, or the raw material powder is reacted and sintered with the superconductor to fix it to the core material, and then the chemical composition and crystal structure of the superconductor are adjusted by annealing. A method for producing a featured ceramic superconducting wire. (2) The method for manufacturing a ceramic superconducting wire according to claim 1, wherein the core material has a circular or rectangular cross section and a radius or thickness in the range of 10 to 75 μm. (3) The method for manufacturing a ceramic superconducting wire according to claim 1, characterized in that the superconducting powder or its raw material powder is adhered to a thickness of 10 to 50% of the radius or thickness of the core material. (4) The ceramic superconducting wire according to claim 1, wherein the dispersion in which the superconductor powder or its raw material powder is dispersed contains a thickener and/or a dispersant. manufacturing method. (5) The ceramic according to claim 1, wherein the core material has a surface coated with a low-reactivity substance to suppress reaction with the superconductor or its raw material powder. A method for manufacturing superconducting wire. (6) A linear core material made of a heat-resistant substance is continuously passed through a liquid dispersion in which superconductor powder or a raw material powder that becomes a superconductor by heat treatment is dispersed in a liquid agent, and the core material is placed on the core material. A step of adhering superconductor powder or its raw material powder, a step of preheating the adhered body to remove the liquid agent by evaporation and decomposition, and a superconducting powder adhered by applying heat treatment to the adhered body from which the solvent has been removed. It is desirable to sequentially perform a step of sintering the superconductor or reacting and sintering the raw material powder with the superconductor to fix it to the core material, and a step of depositing a non-superconductor substance on the superconductor fixed to the core material. After applying several times,
A method for producing a ceramic superconducting wire, further comprising a step of adjusting the chemical composition and crystal structure of the superconductor by annealing. (7) The method for producing a ceramic superconducting wire according to claim 6, wherein the core material has a circular or rectangular cross section and a radius or thickness in the range of 10 to 75 μm. (8) The method for manufacturing a ceramic superconducting wire according to claim 6, characterized in that the superconducting powder or its raw material powder is adhered in an amount of 5 to 50% of the radius or thickness of the core material. (9) The ceramic superconducting wire according to claim 6, characterized in that the dispersion in which the superconductor powder or its raw material powder is dispersed contains a thickener and/or a dispersant. manufacturing method. (10) The ceramic according to claim 6, wherein the core material has a surface coated with a low-reactivity substance for suppressing reaction with the superconductor or its raw material powder. A method for manufacturing superconducting wire. (11) The non-superconducting material is Cu, W, Mo, Ni, Al,
7. The method of manufacturing a ceramic superconducting wire according to claim 6, wherein the material is any metal material selected from the group of Sb-Pb. (12) Non-superconducting material is glass, glass ceramics, Al_2O_3, Y_2O_3, CuO, CaO, M
gO, ZrO_2, BaO, SrO, Ln_XO_Y(
7. The method for manufacturing a ceramic superconducting wire according to claim 6, wherein the material is any inorganic material selected from the group of Ln: rare earth.