JPH07115018A - Manufacture of oxide superconducting insulation coil - Google Patents

Abstract

PURPOSE:To provide a manufacturing method capable of forming an oxide superconductor insulation coil which extracts effectively superconducting properties of an oxide superconducting wire to be used and excellent in magnet properties, such as sizes of a generated magnetic field. CONSTITUTION:This is a manufacturing method for an oxide superconducting insulation coil where a metal sheathed-oxide superconducting wire 1 is rolled in the shape of coils by way of a heat resistant electric insulation layer, thereby producing a rolled product 4; the rolled product 4, which is a raw material for the oxide superconducting material and whose ends are in folded states 11 and 12, is heated over a melting temperature of the oxide superconducting raw material, thereby forming an oxide superconducting layer in the metal sheath. This construction makes it possible to heat-treat a rolled oxide superconducting raw material at a high temperature without allowing the superconducting material to permeating into the insulation layer which is attributable to a short circuit of electric current and provide an oxide superconducting insulation coil whose magnet properties are excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pancake type oxide superconducting insulated coil suitable for forming a magnet in a reliable and efficient manner.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing an insulating coil made of an oxide superconducting wire having a metal sheath, which has a great expectation as a magnet, a coil in a state where the oxide superconducting wires are insulated is formed and then heated. A method of treating to form a continuous superconducting layer has been known (JP-A-2-246).
101, JP-A-3-82105). The heat treatment after coiling causes a problem that since the oxide superconductor layer is fragile, the superconducting properties are deteriorated due to the occurrence of cracks or the like in the winding after forming the continuous layer, or the superconductivity is lost in the entire magnet, This is because it is difficult to perform the winding process while maintaining the integral superconducting layer.

However, in the above-mentioned conventional method, the original magnetic characteristics such as the generated magnetic field based on the superconducting characteristics of the oxide superconducting wire used can be obtained, probably because of the current short circuit in the insulating layer interposed between the oxide superconducting wires. There was a problem that was hard to be caught.

[0004]

DISCLOSURE OF THE INVENTION The present invention is a manufacturing method capable of effectively extracting the superconducting characteristics of an oxide superconducting wire to be used and efficiently forming an oxide superconducting insulated coil having excellent magnet characteristics such as the magnitude of a generated magnetic field. The challenge is to obtain.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to an end of an oxide superconducting wire material in a wound product obtained by winding a metal sheathed oxide superconducting wire material in a coil form through a heat resistant electrical insulating layer. To provide a method for manufacturing an oxide superconducting insulated coil, which comprises forming an oxide superconducting layer in a metal sheath by heating at a temperature above a melting temperature of the oxide superconductor in a bent state. is there.

[0006]

[Function] With the above structure, the wound material of the oxide superconducting wire material can be heat-treated at a high temperature without exuding the superconducting material into the insulating layer that causes a current short circuit, and the superconducting characteristics of the oxide superconducting wire used can be effectively made An oxide superconducting insulated coil that can be pulled out and is excellent in magnet characteristics such as the magnitude of the generated magnetic field can be efficiently obtained.

[0007]

EXAMPLES The manufacturing method of the present invention is to measure the end portion of the oxide superconducting wire material in a wound product obtained by winding the oxide superconducting wire material with a metal sheath wound in a coil shape via a heat resistant electrical insulation layer. The oxide superconducting insulated coil is obtained by heat-treating in a bent state at a temperature higher than the melting temperature of the oxide superconductor to form an oxide superconducting layer in the metal sheath.

In the present invention, an oxide superconducting wire material provided with a metal sheath may be wound in a coil form through a heat resistant electrical insulating layer to form a wound product by any method. By the way, formation of an oxide superconducting wire material with a metal sheath is carried out by, for example, filling a metal tube with powder of an oxide superconductor, and then using an appropriate wire drawing means, rolling means, swaging means such as a die or pinch roll. Can be performed by an arbitrary method such as a method of making a thin wire elongated or flattened, a method of forging.

The oxide superconducting wire material has not only a tape shape as illustrated in FIGS. 1 and 2, but also an appropriate cross-sectional shape such as a round wire shape as illustrated in FIG. 3 and other polygonal shapes. You can do it. The particle size of the oxide superconductor powder to be used is generally 100 μm or less, preferably 0.1 to 10 μm, and the powder can be obtained by, for example, a method of pulverizing a sintered body of the oxide superconductor. .

Further, the oxide superconducting wire material may be in a state in which the oxide superconducting powder inside the metal sheath is pre-sintered and press-treated to crush the formed superconducting layer. The above-mentioned press treatment is effective for stabilizing and improving the quality, and is performed once or twice or more as necessary.
When the press treatment is performed a plurality of times, it is desirable to provide a heating step between the press treatments before and after.

As a material for forming the metal sheath in the oxide superconducting wire material, for example, silver, gold, platinum, stainless steel, an alloy containing such a metal such as a silver-magnesium alloy,
Above all, a noble metal-based material such as a high melting point alloy such as a silver / platinum alloy or a silver / palladium alloy is generally used, but is not limited thereto.

There is no particular limitation on the types of components forming the oxide superconductor inside the metal sheath. Examples thereof include Bi ₂ Sr ₂ CaCu ₂ O _y and Bi _2-x Pb _x Sr ₂ Ca ₂ Cu ₃ O _y.
Bi-based oxide superconductors such as YBa ₂ Cu ₃ O _y and YBa ₂ C
Y-based oxide superconductors such as u ₄ O _y , Ba _- based oxide superconductors such as Ba _1-x K _x BiO ₃ , Nd _- based oxide superconductors such as Nd _2-x Ce _x CuO _y , Tl ₂ Ba Examples include Tl-based oxide superconductors such as ₂ Ca ₂ Cu ₃ O _y , other La-based oxide superconductors, Pb-based oxide superconductors, and the like.

Further, the above-mentioned components such as Bi are substituted with other rare earth elements, the components such as Sr are substituted with other alkaline earth metals, and the O components are substituted with F and the like. To be Furthermore, the thing containing the pinning center etc. is mentioned. The pinning center-containing oxide superconductor has the advantage of exhibiting a large critical current density even under a high magnetic field due to the effect of pinning the magnetic flux by the pinning center. The oxide superconductor containing the pinning center is, for example, the MPMG method (Melt
Powdering Melt Growth) and the like.

Further, as a method of forming a coil-shaped wound product having a heat-resistant electric insulating layer between oxide superconducting wire materials,
For example, a method of coiling an oxide superconducting wire material while interposing a porous heat-resistant insulating material such as a magnesia sheet or a non-woven fabric or a knitted cloth between them (Japanese Patent Laid-Open No. 24-24610).
No. 1 and JP-A-3-82105), or a method of coiling an oxide superconducting wire material coated with a heat resistant electrical insulating layer is a typical example.

The formation of the oxide superconducting wire material coated with the heat resistant electrical insulating layer is carried out by using an inorganic insulating material such as a green sheet made of ceramic powder having heat resistance that does not disappear during heat treatment. Examples thereof include a method of coating the material and a method of providing a polymer layer containing a heat-resistant and electrically insulating oxide powder on the outer periphery of the oxide superconducting wire material. In these cases, the heat treatment for forming the oxide superconducting layer in the metal sheath is used to form the heat-resistant electric insulating layer including a sintered body such as a green sheet or a binder layer of oxide powder. It can also be formed.

In the method of coating with the oxide powder-containing polymer layer, the polymer layer can be applied by a method of applying a paste-like dispersion liquid or the like, and the insulating layer can be efficiently provided by a simple operation and the oxide superconducting wire. It can be easily formed without being affected by the tape form of the material or the outer shape of the round wire, etc. The polymer layer can be made as thin as about 10 to 50 μm, and it has excellent adhesion to the oxide superconducting wire material and is easy to coil. Moreover, the polymer in the polymer layer disappears due to the heat treatment and becomes thinner, and the contained oxide powder remains and binds to the outer periphery of the resulting oxide superconducting wire to efficiently produce an oxide superconducting insulated coil. In addition, it has the advantage that a compact magnet can be formed, and it is easy to obtain an excellent number of windings of a wire rod or generated magnetic field.

Therefore, in the method of coating with the above-mentioned polymer layer containing oxide powder, first, as shown in FIG. 2, for example, the oxide superconducting wire material 1 having the oxide superconductor component 14 in the powder state inside the metal sheath 13 is prepared. The insulated wire material 3 having the polymer layer 2 is formed on the outer periphery, and then the insulated wire material is wound into a predetermined coil form to obtain a wound product 4, and then the wound product is subjected to heat treatment. It is possible to obtain an oxide superconducting insulated coil having

The above-mentioned polymer is a polymer which disappears when it is thermally decomposed when a wound material of an oxide superconducting insulated wire material is heat-treated, and in particular, it disappears at a temperature of 600 ° C. or less and an oxide at room temperature. What functions as a powder binder can be used. As the oxide powder contained in the polymer layer,
Electrically insulative material having heat resistance to withstand the temperature of heat treatment of a wound material of oxide superconducting insulated wire material, especially 800 to 1000 ° C., for example, magnesia, alumina,
Zirconia, yttria, calcium oxide, tantalum oxide, etc. are used.

The wound product may be formed by winding an oxide superconducting material or its insulated wire material in a coil form such as a pancake type or a solenoid type in an appropriate manner. The winding diameter is arbitrary, and an appropriate core body such as a bobbin or a reel can be used in the winding process, and the obtained wound product can be subjected to heat treatment together with the core body. In that case, if it is difficult to perform the post-processing as a post-processing, the bending processing may be performed during the winding processing.

In the present invention, a wound product formed by winding an oxide superconducting wire material with a metal sheath in a coil shape with a heat-resistant electrical insulating layer interposed between the oxide superconducting wire material and the end portion of the oxide superconducting wire material is bent. The oxide superconducting insulated coil is obtained by heating the oxide superconductor at a temperature higher than the melting temperature. FIG. 1 illustrates the bent state. Reference numerals 11 and 12 denote bent portions at the end portions of the oxide superconducting wire material 1 forming the wound product 4.

The bent state of the end portion of the oxide superconducting wire material is, for example, when the wound product is heat-treated at a temperature higher than the melting temperature of the oxide superconductor in its metal sheath, such as twist bending. It is sufficient if the melt does not leak.

The heat treatment is intended to form a continuous oxide superconductor layer by sintering a discontinuous oxide superconductor in the metal sheath of the wound oxide superconducting wire material. Then, the oxide superconducting insulated coil is formed by the heat treatment.

The above-mentioned heat treatment can be carried out by a method involving heating above the melting temperature of the oxide superconductor according to the conventional partial melting method or (complete) melting method. Therefore,
Generally, heat treatment is performed at a temperature of 700 to 1200 ° C.
The obtained oxide superconducting insulated coil can be preferably used as a superconducting magnet or the like.

Example 1 Grain size of Bi ₂ Sr ₂ CaCu ₂ O _y type oxide superconductor 0.1 to 1
0 μm powder was filled in a silver tube with a wall thickness of 1.0 mm and a diameter of 7.0 mm, and it was rolled with a pinch roll to have a width of 3 mm, a thickness of 0.2 mm (thickness of superconducting part 100 μm), and a length of 1 m. After being processed into a tape body, the tape body is dipped in a slurry-like polymer solution in which 15 parts by weight of polyvinyl alcohol and 20 parts by weight of magnesia having an average particle size of 1 μm are mixed with 100 parts by weight of water, and then taken out and dried at 95 ° C. Processed to a thickness of about 4
An insulating wire material having a 0 μm polymer layer on the outer periphery was obtained.

Next, the above-mentioned insulated wire material is bent at its inner end and wound around a reel having a core having a diameter of 2 cm in a superposed state to form a pancake-type roll, and the outer end of the roll is twisted. It was bent and heat-treated at 850 to 890 ° C. for about 50 hours to obtain an oxide superconducting insulated coil.

By the above heat treatment, the polymer component of the polymer layer disappears, a heat-resistant electric insulating layer made of a magnesia binder layer having a thickness of about 20 μm is formed, and the oxide superconducting insulation made of the electric insulating layer and the superconducting wire is formed. A coil was obtained. Its critical temperature is 85K and its critical current density is 4000A /
It was cm ² (77.3K).

Comparative Example An oxide superconducting insulated coil was obtained in the same manner as in Example 1 except that a wound material was formed without bending both ends of the insulated wire material and heat-treated. In this coil, a current short circuit occurs in the insulating layer due to seepage of the oxide superconductor, the critical temperature is 80K, and the critical current density is 1500A / cm ² (77.3.
K).

In the above, the critical temperature is 0.1 A / m.
The temperature change of the electrical resistance was measured by the 4-terminal method while cooling with liquid nitrogen under a current density of m ² , and the generated voltage between the voltage terminals was 0.
Is the temperature at which For the critical current density, the current value was gradually increased while cooling it with liquid nitrogen along with the power lead, and the change in the voltage between the voltage terminals due to the applied current was measured by the 4-terminal method, and it was 1 μv / cm in an XY recorder.
Is a value obtained by dividing the current value when the voltage of appears by the cross-sectional area of the superconductor.

[0029]

According to the present invention, a wound material of an oxide superconducting wire material can be heat-treated at a high temperature without exuding the superconducting substance into the insulating layer which causes a current short circuit, and the superconductivity of the oxide superconducting wire to be used can be improved. It is possible to effectively obtain the characteristics and efficiently obtain the oxide superconducting insulated coil having excellent magnet characteristics such as the magnitude of the generated magnetic field.

[Brief description of drawings]

FIG. 1 is an explanatory view exemplifying a wound object to be heat-treated.

FIG. 2 is a partial cross-sectional explanatory view illustrating a wound material.

FIG. 3 is a cross-sectional view illustrating an insulated wire material.

[Explanation of symbols]

 1: Oxide superconducting wire material 11, 12: End bent portion 13: Metal sheath 14: Oxide superconducting component 2: Heat resistant electrical insulation layer 3: Insulating wire material 4: Wound material

Claims (1)

[Claims] 1. A metal-sheathed oxide superconducting wire material is wound in a coil shape with a heat-resistant electrical insulating layer interposed between the oxide superconducting wire material and the end of the oxide superconducting wire material is bent to oxidize the material. A method for producing an oxide superconducting insulated coil, which comprises forming an oxide superconducting layer in a metal sheath by heat-treating the superconducting material above a melting temperature.