Insulated wire and method for manufacturing an insulating wire

Abstract

The present invention provides an insulating layer-coated wire material that is less likely to lose its superconducting state when the wire material becomes superconducting in a superconducting coil. [Solution] An insulating layer coated wire comprising a wire for coils and an insulating layer covering the surface of the wire, wherein the insulating layer contains a ceramic material.

Description

TECHNICAL FIELD

[0001] The present invention relates to an insulating layer-coated wire and a method for manufacturing the insulating layer-coated wire.

BACKGROUND ART

[0002] In recent years, with the practical application of yttrium-based superconducting materials, it has become possible to bring superconducting materials into a superconducting state at a temperature range higher than the conventional temperature range (about -196°C). Such superconducting materials can be applied to various superconducting application devices (for example, magnetic resonance imaging diagnostic apparatuses (MRI), superconducting magnetic energy storage apparatuses (SMES), metal single crystal pulling apparatuses, etc.), and development of these superconducting application devices is in progress.

[0003] A superconducting material is formed into a wire shape to be a superconducting wire, and a superconducting coil is produced by winding the superconducting wire a plurality of times. When producing a superconducting coil from a superconducting wire, an insulating layer is disposed on the surface of the superconducting wire in order to ensure electrical insulation.

[0004] For example, Patent Document 1 discloses a superconducting coil formed using a superconducting wire provided with such an insulating layer, the superconducting coil including a winding portion formed by co-winding a tape-shaped superconducting wire and an insulating tape (insulating layer), and a resin portion covering at least the outer surface of the winding portion, wherein the superconducting wire has a tape-shaped metal base material, an intermediate layer provided on one main surface of the metal base material, a superconducting layer provided on the surface of the intermediate layer, a protective layer provided on the surface of the superconducting layer, and a stabilization layer covering the metal base material, the intermediate layer, the superconducting layer and the protective layer, the insulating tape (insulating layer) has a tape-shaped insulating base material, a release layer is provided on at least one main surface of the superconducting wire and one main surface of the insulating tape (insulating layer), and the superconducting wire, the release layer, the insulating tape (insulating layer) and the release layer are provided in this order along the radial direction of the winding portion.

[0005] Furthermore, Patent Document 2 discloses an oxide superconducting coil in which an oxide superconducting wire is wound in a coil shape with an insulating layer in between, characterized in that the insulating layer is insulating paper made of alumina fibers with an Al2O3 content of 90% by weight or more. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2024-100341 [Patent Document 2] Japanese Patent Application Publication No. 8-222430 [Overview of the project] [Problems that the invention aims to solve]

[0007] In the superconducting coil described in Patent Document 1, a tape-shaped superconducting wire and an insulating tape (insulating layer) are wound together, but a resin material is used as the material for the insulating tape (insulating layer). Because resin materials have low thermal conductivity, in superconducting coils with such insulating tape (insulating layer) placed on them, the temperature of the superconducting wire tends to rise during operation, making it easier for the superconducting state of the superconducting wire to disappear (i.e., quenching to occur). In this case, there is a problem that the superconducting wire may burn out.

[0008] In the oxide superconducting coil described in Patent Document 2, an oxide superconducting wire and insulating paper made of alumina fibers are wound together, but the insulating paper contains an organic adhesive. Since organic adhesives have low thermal conductivity, in oxide superconducting coils with such insulating paper, the temperature of the oxide superconducting wire tends to rise during operation, and the superconducting state of the oxide superconducting wire tends to disappear (i.e., quenching is likely to occur). In this case, there is a problem that the oxide superconducting wire will burn out.

[0009] This invention was made to solve the above problems, and the object of this invention is to provide an insulating layer coated wire that does not easily lose its superconducting state when the wire becomes superconducting in a superconducting coil. [Means for solving the problem]

[0010] The insulating layer coated wire of the present invention is an insulating layer coated wire comprising a wire for coils and an insulating layer covering the surface of the wire, wherein the insulating layer comprises a ceramic material.

[0011] When the insulating layer contains ceramic material, its thermal conductivity increases. Therefore, even if the temperature of the wire rises when it becomes superconducting, the insulating layer can quickly dissipate the heat from the wire. This makes it easier for the wire to maintain its superconducting state. Furthermore, it prevents the superconducting state from disappearing and prevents the wire from burning out.

[0012] Furthermore, if the insulating layer contains ceramic material, the thermal shrinkage rate of the insulating layer can be reduced. Therefore, even when the insulating layer-coated wire is cooled, the insulating layer is less likely to shrink due to heat, and less stress is likely to occur. Therefore, it is possible to prevent the wire from being damaged by stress generated due to the thermal contraction of the insulating layer.

[0013] Furthermore, in a superconducting coil such as the one described in Patent Document 1, the superconducting wire and insulating tape are wound together, which makes it easy for misalignment to occur between the superconducting wire and the insulating tape. However, in the insulating layer-coated wire of the present invention, since the insulating layer covers the surface of the wire, slippage is less likely to occur when winding the insulating layer-coated wire to create a coil. Therefore, assembly can be improved.

[0014] In the insulating layer coated wire of the present invention, the wire is preferably a superconducting wire. As described above, in the insulating layer-coated wire rod of the present invention, since the insulating layer contains a ceramic material, the thermal conductivity of the insulating layer is high and the thermal shrinkage rate is low. Therefore, when the wire rod is a superconducting wire rod, the insulating layer-coated wire rod of the present invention can be said to be a material suitable for producing a superconducting coil.

[0015] In the insulating layer-coated wire rod of the present invention, it is preferable that the wire rod is configured by laminating a plurality of layers including a superconducting layer. Such a wire rod can function as a superconducting wire rod.

[0016] In the insulating layer-coated wire rod of the present invention, it is preferable that the ceramic material contains at least one selected from the group consisting of Al2O3, SiO2, MgO, Y2O3 and ZrO2. These materials have high thermal conductivity and low thermal shrinkage rate. Therefore, the insulating layer-coated wire rod provided with the insulating layer containing these materials can be said to be a material suitable for producing a superconducting coil.

[0017] In the insulating layer-coated wire rod of the present invention, the thickness of the insulating layer is preferably 1 to 10 μm. When the thickness of the insulating layer is within the above range, the insulating layer is sufficiently thin, so that the coil can be miniaturized when the coil is produced using the insulating layer-coated wire rod. When the thickness of the insulating layer is less than 1 μm, it becomes difficult to ensure insulating properties. When the thickness of the insulating layer exceeds 10 μm, it becomes difficult to miniaturize the coil.

[0018] In the insulating layer-coated wire rod of the present invention, the dielectric breakdown voltage of the insulating layer is preferably 0.1 to 10 kV / mm. When the dielectric breakdown voltage of the insulating layer is within the above range, sufficient insulating properties can be ensured.

[0019] In the insulating layer-coated wire rod of the present invention, the thermal conductivity of the insulating layer is preferably 1.0 to 50 W / mk. When the thermal conductivity of the insulating layer is within the above range, the insulating layer can rapidly release the heat of the wire even if the temperature of the wire rises.

[0020] In the insulating layer-coated wire of the present invention, the density of the insulating layer is preferably 2.0 to 7.0 g / cm 3 . When the density of the insulating layer is within the above range, the insulating layer is sufficiently dense and has sufficient strength.

[0021] The method for producing an insulating layer-coated wire of the present invention is characterized by comprising a coating step of coating the surface of a wire for a coil with an insulating layer containing a ceramic material.

[0022] The insulating layer-coated wire of the present invention described above can be produced by the method for producing an insulating layer-coated wire of the present invention.

[0023] In the method for producing an insulating layer-coated wire of the present invention, in the coating step, the insulating layer is preferably formed by at least one method selected from the group consisting of a sintering method, a sputtering method, a vapor deposition method, and an aerosol deposition method. These methods are suitable as methods for forming an insulating layer containing a ceramic material on a wire. Effects of the Invention

[0024] According to the present invention, it is possible to provide an insulating layer-coated wire in which the superconducting state is less likely to be lost when the wire enters the superconducting state in a superconducting coil. Brief Description of the Drawings

[0025] [Figure 1] Figure 1 is a perspective view schematically showing an example of a superconducting coil constituted by the insulating layer-coated wire of the present invention. [Figure 2] Figure 2 is a cross-sectional view taken along line A-A of Figure 1. [Figure 3] Figure 3 is a cross-sectional view schematically showing an example of the insulating layer-coated wire of the present invention. Modes for Carrying Out the Invention

[0026] The insulating layer coated wire material of the present invention will be described in detail below. However, the present invention is not limited to the following configurations and can be modified and applied as appropriate without changing the gist of the invention. Furthermore, a combination of two or more of the individual preferred configurations of the present invention described below also constitutes the present invention.

[0027] The insulating layer coated wire of the present invention is an insulating layer coated wire comprising a wire for coils and an insulating layer covering the surface of the wire, wherein the insulating layer comprises a ceramic material.

[0028] Such insulating layer-coated wires of the present invention are suitable as wires (superconducting wires) for superconducting coils. A superconducting coil using the insulating layer-coated wire material of the present invention will be described below with reference to the drawings.

[0029] Figure 1 is a schematic perspective view showing an example of a superconducting coil composed of the insulating layer coated wire material of the present invention. Figure 2 is a cross-sectional view taken along line AA in Figure 1.

[0030] The superconducting coil 1 shown in Figure 1 consists of a winding core 100, an insulating layer-coated wire 200 wound multiple times around the winding core 100, and a resin portion 300 that covers the outer surface of the insulating layer-coated wire 200. Note that in Figure 1, a portion of the resin part 300 is shown transparently to make it easier to understand the structure of the insulating layer-coated wire 200.

[0031] As shown in Figure 2, the insulated wire 200 includes a wire 210 for the coil and an insulating layer 220 covering the surface of the wire 210. The cross-section of the insulated wire 200 is rectangular, and the insulating layer 220 covers one surface 210a of the wire 210. Furthermore, as shown in Figure 2, in the superconducting coil 1, the insulating layer-coated wire 200 is wound so that the wire 210 and the insulating layer 220 are positioned alternately. For the sake of clarity in the explanation, Figure 2 shows the thickness (length in Figure 2) as larger than the width (horizontal distance in Figure 2) to make the structure of each component easier to understand. However, in reality, the thickness relative to the width is very small.

[0032] In the insulating layer-coated wire 200, the insulating layer 220 contains a ceramic material. Therefore, the thermal conductivity of the insulating layer 220 is high in the insulating layer-coated wire 200. Consequently, even if the temperature of the wire 210 rises when the wire 210 becomes superconducting, the insulating layer 220 can quickly dissipate the heat from the wire 210. Therefore, the wire 210 is more likely to maintain its superconducting state. Furthermore, it is possible to prevent the superconducting state from disappearing and to prevent the wire 210 from burning out. In other words, in the superconducting coil 1 using the insulating layer-coated wire 200, quenching is less likely to occur.

[0033] Furthermore, if the insulating layer 220 contains a ceramic material, the thermal shrinkage rate of the insulating layer 220 can be reduced. Therefore, even when the insulating layer-coated wire 200 is cooled, the insulating layer 220 is less likely to shrink due to heat, and less stress is likely to occur. Therefore, it is possible to prevent the wire from being damaged by stress generated due to the thermal contraction of the insulating layer 220.

[0034] Furthermore, in a superconducting coil such as the one described in Patent Document 1, the superconducting wire and insulating tape are wound together, which makes it easy for misalignment to occur between the superconducting wire and the insulating tape. On the other hand, in the insulated wire 200, the insulating layer 220 covers one surface 210a of the wire 210. In other words, the insulating layer 220 adheres closely to one surface 210a of the wire 210, resulting in high peel strength. Therefore, when winding the insulated wire 200 to manufacture the superconducting coil 1, misalignment is less likely to occur. For this reason, assembly ease can be improved.

[0035] In the superconducting coil 1, the winding core 100 may be made of, for example, copper, aluminum, nickel, iron, or the like.

[0036] Although the shape of the winding core 100 shown in Figure 1 is annular, it is not particularly limited to any shape that can form a superconducting coil, such as a racetrack shape or an elliptical annular shape.

[0037] In the superconducting coil 1, the resin part 300 may be made of epoxy resin, polyester resin, or the like.

[0038] The preferred structure of the insulating layer-coated wire 200 is described in detail below. Figure 3 is a schematic cross-sectional view showing an example of the insulating layer coated wire material of the present invention. As described above, the insulating layer-coated wire 200 shown in Figure 3 includes a wire 210 and an insulating layer 220 that covers one surface 210a of the wire 210. The cross-section of the insulating layer-coated wire 200 is rectangular.

[0039] As described above, the insulating layer 220 includes a ceramic material, and it is preferable that the ceramic material includes at least one selected from the group consisting of Al2O3, SiO2, MgO, Y2O3, and ZrO2. Among these, Al2O3 is more preferred. These materials have high thermal conductivity and low thermal shrinkage. Therefore, an insulating layer-coated wire 200 having an insulating layer 220 containing these materials is a suitable material for fabricating a superconducting coil 1.

[0040] The thickness of the insulating layer 220 is preferably 1 to 10 μm. If the thickness of the insulating layer 220 is within the above range, the insulating layer 220 becomes sufficiently thin, so when manufacturing the superconducting coil 1 using the insulating layer coated wire 200, the superconducting coil 1 can be miniaturized. If the thickness of the insulating layer is less than 1 μm, it becomes difficult to ensure insulation. When the thickness of the insulating layer exceeds 10 μm, it becomes difficult to miniaturize the coil.

[0041] The dielectric breakdown voltage of the insulating layer 220 is preferably 0.1 to 10 kV / mm. If the dielectric breakdown voltage of the insulating layer 220 is within the above range, sufficient insulation can be ensured.

[0042] The thermal conductivity of the insulating layer 220 is preferably 1.0 to 50 W / mk. If the thermal conductivity of the insulating layer 220 is within the above range, even if the temperature of the wire 210 rises, the insulating layer 220 can quickly dissipate the heat from the wire 210.

[0043] The density of the insulating layer 220 is 2.0 to 7.0 g / cm³. 3 It is preferable that this be the case. When the density of the insulating layer 220 is within the above range, the insulating layer 220 is sufficiently dense and has sufficient strength.

[0044] The method for forming the insulating layer 220 is not particularly limited, but it is preferably formed by sintering, sputtering, vapor deposition, aerosol deposition, etc. Among these, the aerosol deposition method is more preferred.

[0045] By forming the insulating layer 220 using the aerosol deposition method, a dense insulating layer 220 can be formed. Furthermore, since the insulating layer 220 can be formed at room temperature using the aerosol deposition method, the wire 210 is less susceptible to thermal damage during the formation of the insulating layer 220. In addition, the generation of CO2 during the formation of the insulating layer 220 can be suppressed, thereby reducing the environmental impact.

[0046] The wire 210 is composed of multiple layers, including a superconducting layer 213, which are stacked together. More specifically, as shown in Figure 3, the wire 210 is composed of a laminate 215 in which a base layer 211, an intermediate layer 212, a superconducting layer 213, and a protective layer 214 are stacked in that order, and a stabilizing layer 216 that covers the periphery of the laminate 215.

[0047] The base layer 211 is a tape-shaped metal layer, and nickel alloys can be used as its material. Examples of nickel alloys include alloys in which nickel is mixed with cobalt, chromium, molybdenum, tungsten, iron, manganese, silica, carbon, etc. Commercially available Hastelloy® can be used as such a nickel alloy.

[0048] The intermediate layer 212 can be made of metal oxide materials such as cerium or manganese. The formation of the intermediate layer 212 enables high in-plane orientation in the superconducting layer 213.

[0049] The superconducting layer 213 can be made from materials such as yttrium-based superconducting materials, titanium-based superconducting materials, bismuth-based superconducting materials, or mercury-based superconducting materials. Among these, YBa2Cu3O 7-y Yttrium-based superconductors represented by [formula] are preferred. These materials can be made superconducting at high temperatures (above -196°C).

[0050] The protective layer 214 can be made of silver, copper, or the like. The protective layer 214 protects the superconducting layer 213.

[0051] The stabilizing layer 216 can be made of materials such as silver or copper. The stabilizing layer 216 protects the laminate 215.

[0052] The thicknesses of the base layer 211, intermediate layer 212, superconducting layer 213, protective layer 214, and stabilizing layer 216 are preferably set appropriately according to the required performance and the design of the superconducting coil to be manufactured.

[0053] For example, the overall thickness of the wire 210 is preferably 0.03 to 0.3 μm.

[0054] In the above-described insulating layer-coated wire 200, the insulating layer 220 covered only one surface 210a of the wire 210. However, in the insulating layer-coated wire of the present invention, when the insulating layer-coated wire is wound, the position of its formation is not particularly limited as long as the insulating layer covers the surface of the wire so that the wires do not come into direct contact with each other and at least one insulating layer is placed between adjacent wires. For example, an insulating layer may be formed on both opposing surfaces of the wire, or an insulating layer may be formed over the entire surface of the wire.

[0055] In the insulating layer-coated wire 200 described above, the wire 210 was constructed by laminating multiple layers, including a superconducting layer 213. However, the structure of the insulating layer-coated wire of the present invention is not limited to this embodiment, and the wire may be composed solely of superconducting material.

[0056] Next, the method for manufacturing the insulating layer coated wire of the present invention will be described. The present invention provides a method for manufacturing an insulating layer-coated wire, characterized by including a coating step of coating the surface of a wire for coils with an insulating layer containing a ceramic material. Furthermore, the method for manufacturing insulating layer coated wires of the present invention may include a wire preparation step of preparing wires for coils before the coating step. The following describes an example of a method for manufacturing the insulating layer coated wire material of the present invention.

[0057] (Wire preparation process) In the wire preparation process, the wire may be prepared by conventionally known methods. Examples of such methods include the following:

[0058] First, a base layer is prepared, and then an intermediate layer is formed on top of the base layer. Methods such as vapor deposition can be used to form the intermediate layer.

[0059] Next, a superconducting material is coated onto the intermediate layer using a spin coater or the like. As the superconducting material, a solution of an organic complex of Y, Ba, and Cu can be used. By firing this, a superconducting layer is formed.

[0060] Subsequently, a laminate is fabricated by forming a protective layer on top of the superconducting layer. Methods for forming the protective layer include vapor deposition and sputtering. Next, a stabilizing layer is formed around the laminate. Methods for forming the stabilizing layer include vapor deposition and sputtering.

[0061] Through the above process, a wire with a rectangular cross-section can be prepared.

[0062] (Coating process) Next, an insulating layer is formed on one surface of the wire. Methods for forming the insulating layer include sintering, sputtering, vapor deposition, and aerosol deposition. These methods are suitable for forming an insulating layer containing ceramic material on a wire.

[0063] Among the above methods, the aerosol deposition method is preferred. The preferred conditions for the aerosol deposition method are not particularly limited, and for example, the average particle diameter (D 50 One example is a method in which Al2O3 particles with a diameter of 0.1 to 0.9 μm are sprayed at a particle velocity of 200 to 900 mm / s. By forming an insulating layer using the aerosol deposition method, a dense insulating layer can be created. Furthermore, using the aerosol deposition method allows for the formation of an insulating layer at room temperature, making the wire less susceptible to heat damage during the formation of the insulating layer. In addition, it reduces the generation of CO2 during the formation of the insulating layer, thereby lowering the environmental impact.

[0064] The insulating layer coated wire material of the present invention can be manufactured through the above process.

[0065] This specification contains the following information:

[0066] This disclosure (1) is an insulating layer coated wire comprising a wire for a coil and an insulating layer covering the surface of the wire, The above-mentioned insulating layer is an insulating layer coated wire characterized by containing a ceramic material.

[0067] Disclosure (2) states that the wire is an insulating layer coated wire as described in Disclosure (1), which is a superconducting wire.

[0068] Disclosure (3) is an insulating layer coated wire according to Disclosure (1) or (2) wherein the wire is composed of multiple layers including a superconducting layer laminated together.

[0069] Disclosure (4) is an insulating layer coated wire according to any one of Disclosures (1) to (3) wherein the ceramic material comprises at least one selected from the group consisting of Al2O3, SiO2, MgO, Y2O3, and ZrO2.

[0070] Disclosure (5) is an insulating layer coated wire according to any of Disclosures (1) to (4), wherein the thickness of the insulating layer is 1 to 10 μm.

[0071] Disclosure (6) is an insulating layer coated wire according to any of Disclosures (1) to (5), wherein the dielectric breakdown voltage of the insulating layer is 0.1 to 10 kV / mm.

[0072] Disclosure (7) is an insulating layer coated wire according to any of Disclosures (1) to (6), wherein the thermal conductivity of the insulating layer is 1.0 to 50 W / mk.

[0073] This disclosure (8) states that the density of the insulating layer is 2.0 to 7.0 g / cm³. 3 This is an insulating layer coated wire material as described in any of (1) to (7) of this disclosure.

[0074] This disclosure (9) is a method for manufacturing an insulating layer coated wire, characterized by including a coating step of coating the surface of a wire for coils with an insulating layer containing a ceramic material.

[0075] This disclosure (10) is a method for manufacturing an insulating layer coated wire according to this disclosure (9), wherein the insulating layer is formed in the coating step by at least one method selected from the group consisting of sintering, sputtering, vapor deposition and aerosol deposition. [Explanation of Symbols]

[0076] 1. Superconducting coil 100-wound core 200 Insulated wire 210 Wire rod One side of the surface of the 210a wire 211 Foundation Layer 212 Middle Class 213 Superconducting layer 214 Protective layer 215 Laminate 216 Stabilization layer 220 Insulating layer 300 Resin part

Claims

1. An insulating layer coated wire comprising a wire for coils and an insulating layer covering the surface of the wire, The insulating layer is characterized by containing a ceramic material in the insulating layer of the insulating layer.

2. The insulating layer coated wire material according to claim 1, wherein the wire material is a superconducting wire material.

3. The insulating layer coated wire according to claim 1 or 2, wherein the wire is configured by laminating a plurality of layers including a superconducting layer.

4. The aforementioned ceramic material is Al ２ O ３ SiO ２ , MgO, Y ２ O ３ and ZrO ２ The insulating layer coated wire material according to claim 1 or 2, comprising at least one selected from the group consisting of the following.

5. The insulating layer coated wire material according to claim 1 or 2, wherein the thickness of the insulating layer is 1 to 10 μm.

6. The insulating layer coated wire material according to claim 1 or 2, wherein the dielectric breakdown voltage of the insulating layer is 0.1 to 10 kV / mm.

7. The insulating layer coated wire material according to claim 1 or 2, wherein the thermal conductivity of the insulating layer is 1.0 to 50 W / mk.

8. The density of the insulating layer is 2.0 to 7.0 g / cm³. ３ The insulating layer coated wire material according to claim 1 or 2.

9. A method for manufacturing an insulating layer-coated wire, characterized by including a coating step of coating the surface of a wire for coils with an insulating layer containing a ceramic material.

10. The method for manufacturing an insulating layer coated wire according to claim 9, wherein the insulating layer is formed in the coating step by at least one method selected from the group consisting of sintering, sputtering, vapor deposition, and aerosol deposition.

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