JP2001195932A - Ceramic sheet for heat-treatment of metallic composite superconductive rod wire, and method of heat-treating metallic composite rod wire using it, and superconductive magnet and method of fabricating superconductive magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of heat-treating a metallic composite superconductive rod wire using a heat-treating ceramic sheet, and a method of fabricating a superconductive magnet. SOLUTION: A metallic composite superconductive rod wire 1 made of a single core strand or multi-core strand of a bismuth-based oxide superconductor and coated with silver or silver alloy is put upon, and wound with a heat- treating ceramic sheet 2 consisting of an alumina fiber, a zirconia powder and a binder, to thereby fabricate a pan-cake shape coil 3. Then, the coil 3 is heat- treated. The volume ratio of the alumina fiber to the zirconia powder is in the range of 9:1 to 1:9, and the binder is made to disappear by the heat- treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic sheet for heat treating a metal composite superconducting wire, a method for heat treating a metal composite superconducting wire using the same, a superconducting magnet and a method for producing the same.

[0002]

2. Description of the Related Art A typical superconducting wire is Nb.
A metal composite superconducting wire made of a superconducting material, such as Ti, Nb ₃ Al, or Nb ₃ Sn, is produced with a metal and subjected to heat treatment to obtain a high critical current density. Another typical superconducting wire is an oxide superconducting material.The powder of the oxide superconductor or its raw material powder is filled in a metal pipe and subjected to plastic working such as drawing or rolling. Then, a metal composite superconducting wire is manufactured, and heat treatment for obtaining a high critical current density is performed.

When these long metal composite superconducting wires are heat-treated in a bundle or coil state, or when heat-treated in a coil state to produce a superconducting magnet, particularly as a metal material to be combined with a superconducting material, If high-purity Cu, Al, Ag, or the like is used, the metal composite superconducting wires are easily joined to each other, and it is difficult to obtain a metal composite superconducting wire or a superconducting magnet having a predetermined shape.

Therefore, in order to solve the problem that metal composite superconducting wires are joined to each other, a conventional method is disclosed in Japanese Patent Laid-Open No. 6-243745.
As disclosed in Japanese Patent Application Publication, a metal composite superconducting wire in which an oxide superconducting material is coated with a metal made of silver or a silver alloy, and an organic gelatinization that becomes a binder to a powder of alumina or a powder of fiber or magnesia. Heat treatment has been performed by mixing and adding a small amount of an agent to the resulting mixture, and interposing a ceramic sheet obtained by processing between adjacent metal composite superconducting wires.

In the production of a superconducting magnet,
As disclosed in JP-A-2-246101, as an insulating material between coiled metal composite superconducting wires, MgO, ZrO
₂ , heat treatment using Al ₂ O ₃ , SiO _2, and using MgO (magnesia), a superconducting magnet with high critical current density can be obtained without reaction of the metal coating layer of the metal composite superconducting wire It is said.

[0006]

However, the ceramic sheet composed of the alumina fiber and the binder described above is
When the alumina fiber adheres to the surface of the metal coating layer of the metal composite superconducting wire which is softened by heat treatment because of the needle crystal,
There is a problem that it becomes difficult to remove, and after the heat treatment, it tends to remain on the surface of the metal coating layer of the metal composite superconducting wire. For this reason, when making a superconducting cable or superconducting magnet using this metal composite superconducting wire, poor contact with solder etc. makes it difficult to produce the superconducting cable or superconducting magnet, or the surface resistance of the metal composite superconducting wire is high. Problem arises. On the other hand, when using granular alumina powder,
In the heat treatment, the shape of the sheet cannot be maintained, and the metal composite superconducting wires come into contact with each other and have a problem of joining.

[0007] Magnesia powder is a granular crystal and is easy to remove from the surface of the metal composite superconducting wire. However, since magnesia is applied to the surface of the metal composite superconducting wire, the binder added to make a slurry disappears during the heat treatment. It becomes difficult to maintain the shape of the sheet, and adjacent metal composite superconducting wires come into contact with each other, causing a problem of joining. In addition, the lump of the magnesia powder blocks the gas generated inside the metal composite superconducting wire from being released through the outer layer metal part. When heat treatment is performed using a ceramic sheet composed of powder and a binder, it is difficult to release the gas generated inside the wire,
There is a problem that local swelling frequently occurs on the surface of the metal composite superconducting wire. In addition, the mass of the magnesia powder
This is a cause that a change in oxygen partial pressure and a change in a reducing atmosphere, etc., required for heat-treating the metal composite superconducting wire cannot be directly transmitted to the surface of the metal composite superconducting wire. For this reason, the critical current density and the critical temperature, which are important characteristics of the superconducting wire, may be reduced.

Further, when a superconducting magnet is manufactured by using a metal composite superconducting wire that is not coated with an insulating material, the binder is formed even if a ceramic sheet using alumina fiber is used as an insulating material between the metal composite superconducting wires. Since the metal composite superconducting wires come into contact with each other through the gaps between the fibers after the disappearance, there is a problem that insulation is not sufficient.

When a superconducting magnet is manufactured by using a ceramic sheet using magnesia powder as an insulating material, a metal composite superconducting wire must be adjusted to an oxidizing atmosphere or a reducing atmosphere in order to form a mass of magnesia powder during heat treatment. In this case, the gas for adjusting the heat treatment atmosphere is blocked, and the reaction of forming the intended superconducting material cannot be performed in the coil shape inside the metal composite superconducting wire.

An object of the present invention is to provide a ceramic sheet for heat treating a metal composite superconducting wire, a method for heat treating a metal composite superconducting wire using the same, a superconducting magnet and a method for manufacturing the same. Things.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned technical problems, the present invention comprises, in a heat treatment of a metal composite superconducting wire, a material composed of alumina fiber and zirconia powder and a material which disappears by the heat treatment. A ceramic sheet for heat treatment of a metal composite superconducting wire having a binder as a main component is used. Preferably, a ceramic sheet for heat treatment of a metal composite superconducting wire having a volume ratio of the alumina fiber to the zirconia powder of 9: 1 to 1: 9 is used.

A ceramic sheet for heat treatment mainly composed of a binder composed of a material composed of alumina fiber and zirconia powder and a material that disappears by heat treatment is formed so that the zirconia powder is stopped in a mesh made of alumina fiber. Therefore, in the heat treatment of the metal composite superconducting wire, the shape of the sheet is maintained even if the binder disappears, contact and joining of the metal composite superconducting wires by heat treatment can be prevented, and a long metal composite superconducting wire of a predetermined shape can be formed. Obtainable.

When a metal composite superconducting wire is heat-treated using this heat-treating ceramic sheet, the zirconia powder is formed so as to stop the zirconia powder in a mesh made of alumina fiber, and the shape of the sheet is maintained. The metal composite superconducting wire can be adjusted in gas atmosphere because the gap can be provided in the sheet and gas can be easily diffused. In particular, in the case of bismuth-based oxide superconductors that require strict control of the oxygen partial pressure during heat treatment, it is difficult to make the oxygen partial pressure uniform over the entire length of the wire by heat treatment in a coil shape. When zirconia powder is present on the surface of the wire, zirconia assists in binding oxygen to oxygen, and thus has the role of selectively supplying oxygen to the bismuth-based oxide superconductor inside the metal composite superconducting wire. This is effective for pressure equalization.

Further, when the gas generated in the metal composite superconducting wire by the heat treatment is released through the metal coating layer, the gas is not blocked by the ceramic sheet for heat treatment.
Local swelling that appears on the surface of the metal composite superconducting wire can be suppressed. In particular, when heat-treating a metal composite superconducting wire such as a single-core or multi-core wire coated with a bismuth-based oxide superconductor with silver or a silver alloy, the volume ratio of alumina fiber and zirconia powder is 9: 1 to 1: 9. Using a ceramic sheet for heat treatment, 100-300 ° C and 700-820
When the gas generated in the metal composite superconducting wire is released through the metal coating layer by applying a heat treatment in which the temperature rise time of the heat treatment temperature region of 5 ° C. is 5 hours or more, it is not blocked by the ceramic sheet for heat treatment. , Can prevent local swelling appearing on the surface of the metal composite superconducting wire,
A metal composite superconducting wire having a predetermined shape and a high critical current density can be obtained.

When the ceramic sheet for heat treatment of the present invention is used to heat-treat a superconducting magnet produced by winding a metal composite superconducting wire, a material composed of alumina fiber and zirconia powder between adjacent metal composite superconducting wires is used. And through a ceramic sheet for heat treatment mainly composed of a binder made of a material that disappears by heat treatment,
The shape of the sheet is maintained after the heat treatment, and an electrically insulated superconducting magnet can be obtained. Preferably, the volume ratio of the alumina fiber and the zirconia powder is 9:
By using a ceramic sheet for heat treatment of a metal composite superconducting wire that is 1 to 1: 9, a superconducting magnet with excellent superconducting properties that maintains the shape of the sheet after heat treatment and is electrically insulated between the wires. Obtainable.

[0016]

Embodiments of the present invention will be described below. FIG. 1 is a diagram showing a state in which the metal composite superconducting wire 1 is wound around a winding frame 3 in a pancake shape with a ceramic sheet 2 for heat treatment interposed therebetween. In FIG. 1, the metal composite superconducting wire 1 is an example in the case where the cross-sectional shape is a flat angle. Thereafter, a pancake-shaped coil in which the metal composite superconducting wire 1 and the ceramic sheet 2 for heat treatment are wound on the jig 4 for heat treatment is inserted into a heating furnace to perform heat treatment.

The ceramic sheet 2 for heat treatment is obtained by mixing a material composed of alumina fibers and zirconia powder and a binder composed of a material that disappears by heat treatment as a main component, and processing the mixture by mixing them.
As the binder, an organic gelatinizing agent can be used as a material that disappears by heat treatment, and specifically, a cellulose adhesive, a natural rubber adhesive, or the like can be used.

[0018] The ceramic sheet for heat treatment mainly comprising a material composed of alumina fiber and zirconia powder and a binder is a mesh made of zirconia powder made of the alumina fiber, the shape of which is difficult to maintain even if the binder disappears by the heat treatment. By stopping the heat treatment, the shape of the sheet can be maintained even after the heat treatment, and by eliminating the binder by the heat treatment, a gap can be provided in the sheet, and the atmosphere during the heat treatment of the metal composite superconducting wire through the gap can be provided. Can be adjusted.

If the ceramic sheet for heat treatment contains a large amount of alumina fiber, it tends to remain on the surface of the metal composite superconducting wire after heat treatment. Therefore, it is necessary to reduce the volume fraction of the alumina fiber. Although it is easy to do, when the binder disappears during the wire heat treatment, it becomes difficult to keep the prototype, and since the adjacent metal composite superconducting wire during the heat treatment comes into contact, the volume ratio of alumina fiber and zirconia powder is 9: 1 to 1: 9, especially 9: 1
It is preferably 1: 5. Such a ceramic sheet for heat treatment maintains the shape of the sheet even after the heat treatment is completed, and after the binder disappears, a gap can be provided in the sheet, and the adjacent metal composite superconducting wires are joined together. The metal composite superconducting wire can be easily separated, the heat treatment atmosphere can be adjusted, and the metal composite superconducting wire having a predetermined shape can be obtained. In addition, after heat treatment, the ceramic sheet for heat treatment can be easily separated from the metal composite superconducting wire, so when making a superconducting cable or a superconducting magnet, it becomes difficult to connect with solder or the like, or the connection resistance of the metal composite superconducting wire is high. Problem can be solved.

When it is necessary to adjust the heat treatment atmosphere, particularly the oxygen atmosphere, in order to improve the superconducting characteristics such as the critical current of the metal composite superconducting wire, if a heat treatment ceramic sheet made of zirconia powder or alumina fiber is used, zirconia ( ZrO) selectively diffuses oxygen, so it has the effect of balancing the oxygen atmosphere around the metal composite superconducting wire and the oxygen pressure inside the wire, and can be used as a medium to balance the oxygen concentration inside and outside the wire. Therefore, there is an advantage of improving superconductivity. In particular, there is an advantage that the superconducting characteristics of a metal composite superconducting wire made of a single-core wire or a multi-core wire obtained by coating a bismuth-based oxide superconductor or the like with silver or a silver alloy can be improved. However, if the oxide superconductor and zirconia (ZrO) are adjacent to each other, they react and deteriorate, so that it is necessary to provide a wall in which at least 1 μm or more of zirconia (ZrO) does not directly diffuse into the oxide superconductor.

In a metal composite superconducting wire using a bismuth-based oxide superconductor coated with silver, a silver alloy, or the like, a problem that a part of the surface of the metal coating layer of the metal composite superconducting wire locally swells during heat treatment. May occur. This is because the adsorbate (C, H ₂ O, O _2, etc.) attached to the oxide superconductor gasifies during the heat treatment and expands in volume, causing local swelling on a part of the surface of the metal coating layer Probably a phenomenon. When such a phenomenon occurs, the superconducting characteristics such as the critical current and the critical current density of the oxide superconductor are reduced. It is necessary to release gas through the grain boundaries and open ends of the metal coating. In particular, when a metal composite wire is bundled or coiled and heat-treated as in the present invention, an insert such as a ceramic sheet is inserted between the wires, so that a part of the surface of the metal coating layer of the metal composite superconducting wire is formed. Local swelling frequently occurs. Particularly, when magnesia powder is used, local swelling is remarkably exhibited on a part of the surface of the metal coating layer. On the other hand, using the ceramic sheet of the present invention in which the volume fraction of alumina and zirconia was adjusted, when the temperature of the heat treatment was raised, 100-300 ° C. and 700-8
Generated gas is released through the gaps in the ceramic sheet for heat treatment and the metal coating layer of the metal composite superconducting wire by heat treatment in which the temperature rise time in the temperature range of 20 ° C is maintained for 5 hours or more, and the surface of the metal coating layer is released. Local swelling appearing on the surface can be prevented.

When a superconducting magnet is manufactured using a metal composite superconducting wire that is not coated with an insulating material, it is necessary to insulate the wire with an insulating material interposed therebetween. When performing heat treatment on this coil-shaped superconducting magnet for the purpose of improving superconducting properties, there is no reaction between the insulating material and the wire, or gas is diffused to change the atmosphere on the wire surface, for example, a change in oxygen partial pressure. It is necessary to control to an oxidizing atmosphere or a reducing atmosphere, and the ceramic sheet for heat treatment of the present invention is a ceramic sheet for heat treatment mainly composed of a binder and a material composed of alumina fiber and zirconia powder. Even if the binder disappears, the shape of the sheet can be maintained even after the heat treatment by stopping the zirconia powder, which is difficult to maintain its shape, with the mesh made of the alumina fiber, so that the metal composite superconducting wire constituting the superconducting magnet can be maintained. Can be formed with an insulating layer.

As in the heat treatment of the metal composite superconducting wire, the volume ratio of alumina fiber to zirconia powder in the ceramic sheet for heat treatment of the superconducting magnet is from 9: 1 to 1: 1.
9, particularly preferably from 9: 1 to 1: 5. By using this ceramic sheet for heat treatment, when heat-treating a superconducting magnet wound with a metal composite superconducting wire, the binder is eliminated by heat treatment, and a gap is provided in the ceramic sheet, so that the adjacent metal composite superconducting wire Since they are not joined to each other, the heat treatment atmosphere can be adjusted, and there is an advantage of improving superconductivity. In particular, there is an advantage of improving the superconducting properties of a metal composite superconducting wire composed of a single core wire or a multicore wire in which a bismuth-based oxide superconductor or the like is coated with silver or a silver alloy. Hereinafter, the present invention will be described in more detail with reference to examples.

[0024]

EXAMPLE 1 Bi: Pb: Sr: C was prepared using Bi ₂ O ₃ , PbO, SrCO ₃ , CaCO ₃ and CuO.
A powder having a composition ratio of a: Cu = 1.82: 0.33: 1.92: 2.01: 3.02 was prepared. This powder was heat-treated at 750 ° C. for 10 hours and at 800 ° C. for 8 hours, and then pulverized using an automatic mortar to make the obtained sintered body into a powder. Next, the powder obtained by the pulverization was heat-treated at 850 ° C. for 4 hours, and then pulverized again using an automatic mortar. The powder obtained by the pulverization was heat-treated under reduced pressure, and then filled in a silver pipe having an outer diameter of 36 mm and an inner diameter of 30 mm. Next, wire drawing was performed on the silver pipe filled with the powder.
Furthermore, bundle the drawn wire into 61 wires, outer diameter 36mm, inner diameter 31mm
Then, wire drawing and rolling were performed to obtain a tape-shaped metal composite superconducting wire having a thickness of 0.25 mm.

Example 1 Alumina fiber, alumina fiber and magnesia powder, and alumina fiber and zirconia powder were mixed between a metal composite superconducting wire using an oxide superconducting material having a Bi-Pb-based 2223 phase produced by the above steps. The ceramic sheets thus obtained were superposed on each other, wound on a winding frame having a diameter of 50 cm, and then heat-treated at 845 ° C. for 50 hours and at 840 ° C. for 50 hours in the air. In addition, the heating time between 100 to 300 ° C and 700 to 820 ° C was 5 hours in total. For the obtained sample, measurement of the critical current density at 77 K, decomposability after heat treatment of the ceramic sheet, contact state between metal composite superconducting wires after heat treatment (with or without bonding), and metal coating layer of metal-coated superconducting wire The state of local swelling on the surface was visually observed. The results are shown in Table 1. Thus, compared to the case where the alumina fiber alone, the zirconia powder alone, and the ceramic sheet using the alumina fiber and the magnesia powder were used, when the ceramic sheet in which the alumina fiber and the zirconia powder were mixed was used, the metal having a higher critical current density was used. It was found that a coated superconducting wire was obtained. In particular, when the volume ratio of alumina fiber and zirconia powder is 9: 1 to 1: 9 when using a ceramic sheet for heat treatment, particularly, from 9: 1.
When a ceramic sheet for heat treatment of 1: 5 is used, there is no contact or joining of each wire after heat treatment of the ceramic sheet, and further, there is little local swelling of the surface of the metal coating layer,
It has been found that a metal-coated superconducting wire having a high critical current density can be obtained.

Example 2 A ceramic sheet was used as an insulating material, and a coil was wound with the ceramic sheet sandwiched between the above-described metal composite superconducting wires to produce a pancake coil (superconducting magnet) having an inner diameter of 60 mm. Thereafter, the pancake-shaped coil was subjected to a heat treatment at 845 ° C. for 50 hours in an air atmosphere. The heating time between 100-300 ° C and 700-820 ° C is
Total time was 5 hours. The critical current density of the fabricated pancake-like coil at 77K, the evaluation of the contact state between the metal composite superconducting wires constituting the pancake-like coil, and the reactivity of the ceramic sheet with the metal coating layer silver of the metal composite superconducting wire It was visually observed. Table 2 shows the results. Even in the case of a pancake-shaped coil (superconducting magnet), a ceramic sheet in which alumina fiber and zirconia powder are mixed is used as compared with a case in which alumina fiber alone, zirconia powder alone, and a ceramic sheet for heat treatment using alumina fiber and magnesia powder are used. When used, the critical current density was found to be high. In particular, when the volume ratio of alumina fiber and zirconia powder is 9: 1 to 1: 9, a ceramic sheet for heat treatment is used, the shape of the ceramic sheet is maintained even after the heat treatment, and there is no contact between the metal composite superconducting wires, It was found that a healthy pancake-like coil with less local swelling on the surface of the metal-coated layer of the metal-coated superconducting wire constituting the pancake-like coil while maintaining the insulating layer was obtained.

Example 3 When the heat treatment of the metal composite superconducting wire of Example 1 was carried out, if the heat-up rate was high, local swelling occurred on a part of the surface of the metal coating layer of the metal composite superconducting wire. Since such swelling of the metal composite superconducting wire causes a reduction in critical current density, the main component of the gas in the swelling portion was evaluated by differential thermal analysis-mass spectrometry (TG-MS).
It was found that H ₂ O and CO ₂ were generated in a temperature range of 700 ° C. and 700-820 ° C. Therefore, the heating rate of the heat treatment was changed to change the heating time of 100 to 300 ° C, the heating time between 700 to 820 ° C, and the heating time between 100 to 300 ° C and 700 to 820 ° C. The number of local swelling per unit length of the surface of the metal coating layer of the metal composite superconducting wire, which appeared in each case, was measured. The results are shown in Table 3. Thus, when heat-treating a metal composite superconducting wire using a bismuth-based oxide superconductor coated with silver or a silver alloy at a high temperature rising rate, especially when heat-treating a metal composite wire in a bundle or coil shape However, local swelling is likely to occur on a part of the surface of the metal coating layer of the metal composite superconducting wire, but the heat-up time in the temperature range of 100 to 300 ° C and 700 to 820 ° C is maintained for 5 hours or more, and heat treatment is performed. It was found that the generated gas was released through the gaps in the ceramic sheet and the metal coating layer of the metal composite superconducting wire, thereby preventing the phenomenon of causing local swelling on a part of the surface of the metal coating layer.

Example 2 Using Bi ₂ O ₃ , SrCO ₃ , CaCO ₃ and CuO powder, Bi: Sr: Ca: Cu =
A powder having a composition ratio of 2: 2: 1: 2 was prepared. Using this powder,
Calcination and pulverization were performed several times to prepare a powder of a Bi-based 2212 composition. After making this powder into a sintered body by isostatic pressing,
Heat treatment was performed under reduced pressure. A silver pipe having an outer diameter of 12 mm and an inner diameter of 8 mm was filled, and then the silver pipe filled with the powder was drawn. Furthermore, bundle the drawn wires into 61 wires,
It was fitted with a silver pipe having a diameter of 12 mm and an inner diameter of 10 mm, and then subjected to wire drawing and rolling to obtain a tape-shaped metal composite superconducting wire having a thickness of 0.25 mm. Bi-based 2212 produced by the above process
Alumina fiber alone, zirconia powder alone, alumina fiber and magnesia powder, and a ceramic sheet in which alumina fiber and zirconia powder are mixed between metal composite superconducting wires using an oxide superconducting material having a phase. After being wound on a winding frame having a diameter of 50 cm, each was subjected to a heat treatment at 890 ° C. for 5 minutes and 860 ° C. for 20 hours in the air. In addition, the heating time between 100 to 300 ° C and 700 to 820 ° C was 5 hours in total. For the obtained sample, measurement of the critical current density at 77 K, decomposability after heat treatment of the ceramic sheet, contact state between metal composite superconducting wires after heat treatment (with or without bonding), and metal coating layer of metal-coated superconducting wire The local swelling state of the surface was visually observed. Table 4 shows the results. The metal composite superconducting wire using the oxide superconducting material having the Bi-based 2212 phase also has a higher alumina fiber compared to the alumina fiber alone, the zirconia powder alone, and the ceramic sheet for heat treatment using alumina fiber and magnesia powder. It was found that a metal-coated superconducting wire having a high critical current density was obtained when a ceramic sheet in which zirconia powder and zirconia powder were mixed was used. In particular, the volume ratio of alumina fiber and zirconia powder is from 9: 1 to 1: 9
When the ceramic sheet for heat treatment is used, the decomposability of the ceramic sheet after the heat treatment is good, there is no contact between the metal composite superconducting wires, and further, the metal-coated superconducting wire having little local swelling on the surface of the metal coating layer is obtained. It turned out to be obtained.

[0029]

As described above, by using the ceramic sheet having the alumina fiber and the zirconia powder of the present invention, the shape of the sheet is maintained even if the binder disappears in the heat treatment of the metal composite superconducting wire, It can prevent joining of metal composite superconducting wires by heat treatment,
A long metal composite superconducting wire having a predetermined shape can be obtained. In addition, a gap can be provided in the ceramic sheet during the heat treatment, and gas is easily diffused, so that the gas atmosphere around the metal composite superconducting wire can be adjusted. Furthermore, when the gas generated in the metal composite superconducting wire by heat treatment is released through the outer layer metal part, it is not blocked by the ceramic sheet for heat treatment, so local swelling that appears on the surface of the metal composite superconducting wire is suppressed. And a long metal-coated superconducting wire having a high critical current can be obtained.

Further, when a heat treatment is performed on a superconducting magnet produced by winding a metal composite superconducting wire using the ceramic sheet for heat treatment of the present invention, the shape of the sheet is maintained even after the heat treatment, and the electrically insulated sound is maintained. A superconducting magnet can be obtained.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

[Brief description of the drawings]

FIG. 1 is a view showing a state of being wound into a pancake shape with a ceramic sheet for heat treatment interposed between adjacent metal composite superconducting wires used in an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal composite superconducting wire 2 Ceramic sheet for heat treatment 3 Reel 4 Heat treatment jig

Claims (8)

[Claims] 1. A ceramic sheet for heat treatment of a metal composite superconducting wire mainly comprising a binder composed of a material composed of alumina fiber and zirconia powder and a material that disappears by heat treatment. 2. The ceramic sheet for heat-treating a metal composite superconducting wire according to claim 1, wherein a volume ratio of the alumina fiber and the zirconia powder is from 9: 1 to 1: 9. 3. A heat treatment method for a metal composite superconducting wire, wherein the heat treatment is carried out between adjacent metal composite superconducting wires via the ceramic sheet for heat treatment according to claim 1 or 2. 4. The heat treatment of a metal composite superconducting wire according to claim 3, wherein the metal composite superconducting wire is a single-core wire or a multi-core wire obtained by coating a bismuth-based oxide superconductor with silver or a silver alloy. Method. 5. A heat treatment temperature range of 100 to 300 ° C. and 700 to 820 ° C. for at least 5 hours using the ceramic sheet for heat treatment according to claim 1 or 2. Item 6. A method for heat treating a metal composite superconducting wire according to Item 4. 6. A superconducting magnet formed by winding a metal composite superconducting wire, wherein the superconducting magnet is electrically insulated between adjacent metal composite superconducting wires via a ceramic sheet for heat treatment. 7. The superconducting magnet according to claim 6, wherein the metal composite superconducting wire is a single-core wire or a multi-core wire obtained by coating a bismuth-based oxide superconductor with silver or a silver alloy. 8. The superconducting magnet according to claim 7, wherein the superconducting magnet is heat-treated between adjacent metal composite superconducting wires via the ceramic sheet for heat treatment according to claim 1 or 2. Manufacturing method