Connection structure

Abstract

Connection structure (20), which includes: a first and a second superconducting wire (10a, 10b), which are two superconducting wires comprising a ribbon-shaped base material (1), an intermediate layer (2) formed on the base material (1), and a superconducting conductor layer (3) formed on the intermediate layer (2), a connecting superconducting conductor layer (8) which connects the first and second superconducting wire (10a, 10b) in a positional relationship in which the surfaces of the superconducting conductor layers (3) are facing each other, and together with the first and second superconducting wire (10a, 10b) forms a superconducting connecting section (C), two protective materials (7, 7) arranged on the respective sides of the base materials (1) of the first and second superconducting wire (10a, 10b) in a positional relationship in which they clamp and cover the superconducting connecting section (C), and which are wider than the first and second superconducting wire (10a, 10b), and Metal sections (9) made of meltable material connecting the two protective materials (7) together, wherein the metal sections (9) are formed on the inner surfaces of the two protective materials (7, 7) at locations arranged along the superconducting wires (10a, 10b) where the superconducting connecting section (C) is not positioned.

Description

[Technical field]

[0001] The present invention relates to a connecting structure, in particular a connecting structure of superconducting wires. [Background technology]

[0002] In recent years, oxide superconductors with a critical temperature (Tc) higher than the temperature of liquid nitrogen (approximately 77 K) have attracted attention, such as YBCO-based (yttrium-based) or BSCCO-based (bismuth-based) high-temperature superconductors. Superconducting wires fabricated using such high-temperature superconductors include superconducting wires with a superconducting conductor layer formed by depositing an oxide superconductor film on a metal plate of a long, flexible metal, or similar material, or by depositing an oxide superconductor film on a single-crystal substrate.

[0003] Regarding superconducting wires, the use of superconducting wires as coil winding wires, for example, for MRI (magnetic resonance imaging) or NMR (nuclear magnetic resonance), has been investigated, and the demand for long superconducting wires is increasing. However, since the length of a single uninterrupted superconducting wire is subject to manufacturing limitations, it is necessary to connect superconducting wires to achieve the desired coil winding wire.

[0004] As a connecting structure for connecting superconducting wires, JP2011-165435A discloses a superconducting wire connecting structure in which the ends of two superconducting wires coated with reinforcement on both sides are superimposed and connected by solder. However, since the connecting structure in Patent Document 1 uses solder to connect the superconducting wires, it was difficult to reduce the electrical resistance of the connecting portion of the superconducting wires to zero due to the position of the solder.

[0005] As another method for connecting superconducting wires to each other, JP2013-235699A discloses a method in which an exposed superconducting conductor layer at the connecting end of one superconducting wire and an exposed superconducting conductor layer at the connecting end of the other superconducting wire are arranged opposite each other, and a superconducting compound layer formed by an MOD (metal organic deposition) method is formed therebetween.

[0006] However, although the connection structure described in JP2013-235699A connects the superconducting wires to each other by the superconducting interconnect layer formed by the MOD process between the superconducting conductor layer of one superconducting wire and the superconducting conductor layer of the other superconducting wire, the superconducting interconnect layer itself has low strength. Therefore, if undesirable external forces act on the superconducting wires, there was a risk of the superconducting wires detaching from the superconducting interconnect layer.

[0007] The closest prior art to the present invention is disclosed in JP2015-213006A. This document already discloses a connecting structure comprising first and second superconducting wires, which are superconducting wires comprising a tape-shaped base material, an intermediate layer formed on the base material, and a superconducting conductor layer formed on the intermediate layer, and a connecting superconducting conductor layer that connects the first and second superconducting wires in a positional relationship in which the surfaces of the superconducting conductor layers face each other, and forms a superconducting connecting portion together with the first and second superconducting wires.Furthermore, JP S58-5309 U shows two protective materials arranged on the respective sides of the base materials of the first and second superconducting wires in a positional relationship that clamps the superconducting connecting portion, and which are wider than the first and second superconducting wires, and include metal portions that connect the two protective materials. Similar prior art also arises from JP2007-012582A, CN 101971273A, and CN 104710186A. [Summary of the invention][Technical problem]

[0008] The present invention therefore intends to provide a connection structure of superconducting wires having a high connection strength. [Solution to the task]

[0009] This object of the present invention is achieved with the features of claim 1. The subclaims show advantageous developments of this invention.

[0010] The connecting structure according to the present invention comprises a first and a second superconducting wire, which are two superconducting wires comprising a tape-shaped base material, an intermediate layer formed on the base material, and a superconducting conductor layer formed on the intermediate layer; a connecting superconducting conductor layer that connects the first and second superconducting wires in a positional relationship in which the surfaces of the superconducting conductor layers face each other and forms a superconducting connecting portion together with the first and second superconducting wires; two protective materials that are arranged on the respective sides of the base materials of the first and second superconducting wires in a positional relationship in which they clamp the superconducting connecting portion and that are wider than the first and second superconducting wires;and metal sections that connect the two protective materials.

[0011] Furthermore, in the above connection structure, the first and second superconducting wires preferably each further have a metal protective layer covering the superconducting conductor layer over the entire area except for the superconducting connection portion.

[0012] Furthermore, in the above connecting structure, the metal portions are preferably provided at at least four locations surrounding the superconducting connecting portion.

[0013] Furthermore, in the above connecting structure, the metal portions are preferably a metal or an alloy containing at least Ag, Au and / or Cu.

[0014] Furthermore, in the above connection structure, the difference between the elastic coefficient of the base material and the elastic coefficient of the protective materials is preferably in a range of less than or equal to 80 GPa.

[0015] Furthermore, in the above connection structure, the elastic coefficient of the protective materials is preferably 150 GPa to 250 GPa.

[0016] Furthermore, in the above compound structure, the melting point of the protective materials is preferably greater than or equal to 1000°C.

[0017] Furthermore, in the above connection structure, the thickness of the protective materials is preferably 30 µm to 300 µm.

[0018] Furthermore, the protective materials are preferably a Ni-based alloy, stainless steel or carbon steel. [Effects of the invention]

[0019] According to the present invention, a connection structure of superconducting wires having high connection strength can be provided, and the yield of the production thereof can be improved. [Brief explanation of the figures] [ Fig. 1] Fig. 1 is a schematic cross-sectional view of a superconducting wire constituting an interconnection structure according to the present invention. [ Fig. 2] Fig. 2 is a schematic cross-sectional view of a connection structure of a first embodiment according to the present invention. [ Fig. 3] Fig. 3 is a plan view of the Fig. Connection structure shown in Figure 2. [ Fig. 4] Fig. 4A to 4D are diagrams for explaining the manufacturing process of the connection structure. [ Fig. 5] Fig. 5 is a schematic cross-sectional view of the connection structure of a second embodiment according to the present invention. [ Fig. 6] Fig. 6 is a schematic cross-sectional view of the connection structure of a third embodiment according to the present invention. [ Fig. 7] Fig. 7 is a perspective view of the connection structure of a fourth embodiment according to the present invention. [ Fig. 8] Fig. 8A is a plan view of the connection structure of a fifth embodiment according to the present invention, and Fig. Figure 8B is a perspective view showing a connection structure in Fig. 8A forming the metal section is shown pulled out. [ Fig. 9] Fig. 9 is a schematic perspective view of the connection structure according to a sixth embodiment of the present invention. [ Fig. 10] Fig. 10 is a schematic perspective view of the connection structure according to a seventh embodiment of the present invention. [Forms for carrying out the present invention]

[0020] The following connection structures of the present invention are explained with reference to the figures. Hereinafter, a numerical range expressed by "to" means the range in which the numerical values ​​indicated before and after "to" are included as the lower and upper limits. (First embodiment)<Supraleitender Draht>

[0021] Fig. Figure 1 is a schematic cross-section of a superconducting wire constituting the interconnection structure according to the present invention. Fig. 1 is constructed as a layered structure of a base material 1, an intermediate layer 2, and a superconducting conductor layer 3, wherein the intermediate layer 2 and the superconducting conductor layer 3 are formed in this order on a surface 1a in the thickness direction of the base material 1 for superconductor film formation.

[0022] The base material 1 consists of a ribbon-shaped, weakly magnetic metal substrate or a ceramic substrate. The material of the metal substrate can be, for example, metals with excellent strength and heat resistance, such as Co, Cu, Cr, Ni, Ti, Mo, Nb, Ta, W, Mn, Fe, Ag, etc., or their alloys. From the perspective of excellent corrosion resistance and heat resistance, the use of a Ni-based alloy such as Hastelloy®, Inconel®, etc., or an Fe-based alloy such as stainless steel, etc., is particularly preferred, and the use of the Ni-Fe-Mo-based alloy Hastelloy® is more preferred. Although the thickness of the base material 1 is not particularly limited, 30 to 100 μm is preferable, and 30 to 50 μm is more preferable.

[0023] The intermediate layer 2 is a base layer formed on the base material 1, for example, to achieve a high biaxial orientation of the superconducting conductor layer 3. Such an intermediate layer 2 consists, for example, of a material whose physical properties such as thermal expansion coefficient, lattice constant, etc., represent an average value of the base material 1 and the superconductor that forms the superconducting conductor layer 3. Furthermore, the intermediate layer 2 can have either a single-layer structure or a multi-layer structure. If the intermediate layer 2 is formed as a multi-layer structure, there is no restriction regarding the number and type of layers, although it can be constructed, for example, such that an amorphous Gd2Zr2O 7-δ(δ is the oxygen substoichiometry), Al2O3 or Y2O3 etc. containing bed layer, a crystalline MgO etc. formed by IBAD (Ion Beam Assisted Deposition) process layer of forced alignment and a LaMnO 3+δ (δ is the oxygen superstoichiometry) may be deposited in the order. Furthermore, a cap layer containing CeO2, etc., may also be provided on the LMO layer. Although the thickness of the above respective layers is not particularly limited, as an example, the thickness of the Y2O3 layer of the bed layer is 7 nm, the Al2O3 layer is 80 nm, the MgO layer of the forced alignment layer is 40 nm, and the LMO layer is 30 nm.

[0024] The superconducting conductor layer 3 is formed on the intermediate layer 2. The superconducting conductor layer 3 is preferably formed of a high-temperature superconductor whose transition temperature is higher than the boiling point of liquid nitrogen (-196°C : 77 K), more preferably, a copper oxide superconductor. A high-temperature superconductor such as REBa2Cu3O is suitable as the copper oxide superconductor. 7-δ(RE-based superconductor) is preferred. In RE-based superconductors, RE is a single rare earth element or a plurality of rare earth elements such as Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, etc. Furthermore, the oxygen substoichiometry δ is, for example, ≥ 0 and ≤ 1, and from the perspective of a high superconductor transition temperature, the closer to zero, the more preferable. δ may also be below zero, i.e., a negative value, when high-pressure oxygen annealing is performed using a device such as an autoclave, etc. The thickness of the superconducting conductor layer 3 is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

[0025] Furthermore, the superconducting wire 10 preferably further includes a metal protective layer 4 covering the superconducting conductor layer 3 over the entire surface except for a later-described superconducting connecting portion C. In addition, the superconducting wire 10 may further include a metal protective layer 4 on a surface 1b of the base material 1 opposite to the surface 1a on which the intermediate layer 2 is formed. The metal protective layer 4 is preferably a metal or alloy layer containing at least Ag, Au, and / or Cu, with an Ag metal layer being more preferred. The metal protective layer 4 may be made of the same material as or different from the metal portions 9 described later. The thickness of the metal protective layer 4 is preferably 30 to 300 µm, and more preferably 30 to 100 µm.When the metal protective layer 4 is formed on the surface of the superconducting conductor layer 3, the surface of the superconducting conductor layer 3 can be effectively protected without being exposed. Furthermore, when the metal protective layer 4 is provided on the surface 1b side of the base material 1, the protective materials 7 and the superconducting wires 10 can be connected in a connection structure 20 described later via the metal protective layer 4 provided on the surface 1b side of the base material 1. This can further strengthen the reinforcing effect of the superconducting connection portion C. There is no particular limitation on the length direction dimension of the metal protective layer 4, so the metal protective layer 4 can be formed either longer or shorter than the protective materials 7, or the same length as the protective materials 7. <verbindungsstruktur>

[0026] Fig. 2 is a schematic cross-sectional view of a connection structure of a first embodiment according to the present invention, and Fig. 3 is a plan view of the Fig. 2. The illustrated interconnection structure 20 includes two superconducting wires, namely a first superconducting wire 10a (hereinafter referred to simply as "superconducting wire 10a") and a second superconducting wire 10b (hereinafter referred to simply as "superconducting wire 10b"), a connecting superconducting conductor layer 8, two protective materials 7, 7, and metal portions 9.

[0027] In Fig. 2, the superconducting wires 10a, 10b are connected to each other with the respective ends in an opposite positional relationship of the surfaces of the superconducting conductor layers 3, 3 via the superconducting conductor layer 8 to be connected, wherein the superconducting conductor layer 8 to be connected together with the superconducting wires 10a, 10b forms the superconducting connecting section C (section shown in Fig. 2 is surrounded by a dashed line). Furthermore, two protective materials 7, 7 having a greater width than the superconducting wires 10a, 10b are arranged in a positional arrangement centering the superconducting connecting portion C on the side of the respective base material 1, 1 of the superconducting wires 10a, 10b. In addition, the two protective materials 7, 7 are connected to each other via metal portions 9, which are arranged at positions on both sides transverse to the width direction of the respective superconducting wires 10a, 10b, preferably at at least four positions surrounding the superconducting connecting portion C (in Fig. 3 the four corner positions of the protective materials 7) are formed.

[0028] Such a connection structure 20 has a sandwich structure in which the superconducting wires 10a, 10b are sandwiched between the two protective materials 7, 7, and the protective materials 7, 7 are interconnected by the metal portions 9. Therefore, the superconducting connection portion C is reinforced by the two protective materials 7, 7, so that the connection of the superconducting wires 10a, 10b can be kept solid.

[0029] The two protective materials 7, 7 are secured by the metal portions 9 in a state where mutual attractive forces act to such an extent that the thickness does not change in the direction centering the superconducting wires 10a, 10b. As a result, in the interconnection structure 20, the superconducting wires 10a, 10b are interconnected with high interconnection strength. This effectively suppresses the occurrence of separation between the superconducting wires 10a, 10b at the superconducting interconnection portion C, and improves the yield of the interconnection structure 20.Furthermore, the superconducting connecting portion C is covered by the two protective materials 7, 7, so that effective protection is possible, and even when an external stress such as undesirable external forces is applied to the connecting structure 20, destruction of the superconducting connecting portion C can be effectively suppressed. Furthermore, since the metal portions 9 are provided at positions remote from the superconducting connecting portion C, the risk of the superconducting conductor layer 8 to be connected being burned off due to the influence of the connection (melting) of the metal portions 9 to each other can be reduced.

[0030] In addition, a gap G is formed between the two protective materials 7, 7 so that an oxygen supply path can be ensured during the production of the connecting structure 20, whereby crystallization of the superconducting conductor layer 8 to be connected can be promoted. (Superconducting conductor layer to be connected)

[0031] The superconducting conductor layer 8 to be bonded is preferably composed of the same composition of superconductors as the superconducting conductor layer 3. In particular, formation using a composition (solution) containing a starting material required for forming an RE-based superconductor is possible. As such a solution, for example, an acetylacetone-based, naphthenate-based MOD solution containing RE (rare earth metals such as Y (yttrium), Gd (gadolinium), Sm (samarium), and Ho (holmium), etc.), Ba, and Cu in a ratio of approximately 1:2:3 can be used. The crystalline superconducting conductor layer 8 to be bonded can be obtained by applying the MOD solution to the superconducting wires 10a, 10b and firing them under specific conditions. (protective material)

[0032] Next, the protective material 7 will be explained in detail. The protective material 7 is preferably a material capable of pressure firing together with the superconducting wires 10a, 10b constituting the superconducting connecting portion C, and is preferably a material that can withstand a firing temperature of about 800°C. Consequently, the melting point of the protective material 7 is preferably at or above 1000°C, and more preferably at or above 1200°C. Furthermore, a mutual attractive force is preferably applied between the two protective materials 7, 7 to such an extent that forces act on the superconducting connecting portion C. Therefore, while the protective material 7 is preferably composed of the same material as the base material 1 of the superconducting wires 10a, 10b having such strength and heat resistance, it may also be composed of a material different from the base material 1.As such a protective material 7, for example, a metal material such as a Ni-base alloy, a stainless steel or a carbon steel, etc. can be mentioned.

[0033] Furthermore, in the protective material 7, from the aspect of the strength balance between the respective parts constituting the joint structure 20, the difference between the elastic coefficient of the base material 1 and the elastic coefficient of the protective material 7 is preferably in a range of less than or equal to 80 GPa. This is because if the difference in the elastic coefficients is greater than 80 GPa, uniform stress will not act on the joint portion, thus preventing a good joint.

[0034] Although the elastic coefficient of the protective material 7 can be determined taking into account the difference from the elastic coefficient of the base material, it is not particularly limited, but it is preferably, for example, 150 GPa to 250 GPa, and more preferably 160 GPa to 230 GPa.

[0035] The thickness of the protective material 7 is preferably 30 μm to 300 μm, and more preferably 30 μm to 100 μm. If the thickness of the protective material 7 is less than 30 μm, there is a risk that the protective material 7 itself will be destroyed by the pressurization in the main firing step described later, and there is also a risk that the protective material 7 will not achieve a sufficient reinforcing effect for the superconducting connection portion C, so that the superconducting connection portion C cannot be sufficiently protected from external stress. On the other hand, if the thickness of the protective material 7 exceeds 300 μm, there is a risk that no stress will be applied to the connection portion and the connection will be insufficient, so that the critical current value Ic will decrease significantly.Therefore, by setting the thickness of the protective material 7 in a range of 30 µm to 300 µm, a decrease in the critical current value Ic, which is the maximum current flowing in the superconducting conductor layer 3, can be suppressed while reinforcing the superconducting connection portion C. The critical current value Ic can be determined, for example, by measuring the terminal resistance of the superconducting connection portion C using a four-wire measurement.

[0036] The width of the protective material 7 changes according to the width of the superconducting wires 10a, 10b. Although the width of the protective material 7 should only be wider than the superconducting wires 10a, 10b, and there is no particular limitation, it is preferable that the width be wider than the width of the superconducting wires 10a, 10b by 2 to 10 mm, and more preferably by 2 to 5 mm. (metal sections)

[0037] The metal portions 9 are respectively provided on the opposite inner surfaces of the two protective materials 7, 7 and connect the two protective materials 7, 7 to each other. Here, the metal portions 9 are formed on the inner surfaces of the two protective materials 7, 7 at a location where the superconducting connecting portion C is not positioned. Further, when the superconducting wires 10a, 10b are pressure-fired over the superconducting conductor layer 8 to be connected and the superconducting connecting portion C is formed, it is preferable that the protective materials 7 be a material that can withstand a firing temperature of about 800°C, and on the other hand, the metal portions 9 be a reflowable material. Therefore, the metal portions 9 preferably have a different material than the protective materials 7.Although the metal portions 9 should be only one metal that can bond the metal portions 9, 9 provided on the respective inner surfaces of the two protective materials 7, 7 to each other, and there is no particular limitation, it is preferably, for example, a metal or alloy that includes at least Ag, Au, and / or Cu, with Ag being more preferred. The thickness of the metal portions 9 is preferably 10 nm to 10 μm, and more preferably 10 nm to 2 μm. While there is no particular limitation on the formation of the metal portions 9, any known method that can form the metal portions 9, such as sputtering, vacuum deposition, paste application, etc., can be used. (Manufacturing process of the connection structure)

[0038] Next, the manufacturing method of the connecting structure according to the present invention will be described with reference to Fig. 4A to Fig. 4D explained. Fig. 4A is a schematic cross-sectional view showing a step of applying a starting material for forming the superconducting conductor layer 8 to be connected to the superconducting wires 10a, 10b. Fig. Figure 4B is a schematic cross-sectional view showing a step of pre-firing the superconducting wires 10a, 10b on which the starting material has been applied. Fig. 4C is a schematic perspective cross-sectional view showing a step immediately before forming an interconnection structure using the superconducting wires 10a, 10b and two protective materials 7. Fig. Figure 4D is a schematic cross-section of the connecting structure 20 formed by the steps of Fig. 4A to 4C. When the superconducting wires 10a, 10b are coated with a metal protective layer 4, the metal protective layer 4 of the connecting end side is first removed in a rectangular manner across the entire width of the superconducting wires 10a, 10b. The rectangular removal of the metal protective layer 4 is carried out by means of mechanical polishing, chemical polishing (e.g., an etching treatment), or a combination thereof (removal step). The rectangular removal of the metal protective layer 4 is carried out to a depth at which the superconducting conductor layer 3 is completely exposed. The surface roughness of the exposed superconducting conductor layer 3 is preferably sufficiently small, with its surface roughness (center line roughness Ra) of less than or equal to 50 nm being preferred, and less than or equal to 10 nm being more preferred.The surface roughness is the arithmetic mean roughness value Ra with respect to the "mean amplitude parameter in the height direction" of the surface roughness parameter defined according to JIS B 0601:2001.

[0039] Then, as in Fig. As shown in Figure 4A, an MOD solution 30 is poured into the removal section of the metal protective layer 4 of the superconducting wires 10a, 10b by an MOD (Metal Organic Deposition) method by spin coating or coating (coating step). As the MOD solution, a metal-containing composition (solution) composed of the same composition system as the superconducting conductor layer 3 is preferred.

[0040] Here, the same composition system as the superconducting conductor layer 3 means that, for example, when an RE-based superconductor is used as the high-temperature superconductor constituting the superconducting conductor layer 3, the composition (solution) for forming the superconducting conductor layer 8 to be bonded is also composed of a composition (solution) required for forming an RE-based superconductor. That is, the composition (solution) includes a raw material required for forming the RE-based superconductor, and the superconducting conductor layer 3 and the superconducting conductor layer 8 to be bonded are composed of the same superconductor composition of the RE-based superconductor.Although the solvent containing the composition (solution) is not particularly limited as long as it can dissolve the desired superconductor system, and further, a connecting superconducting conductor layer 8 with good crystallinity can be obtained after the main firing step, for example, an acetylacetone-based or naphthenate-based MOD solution containing RE (rare earth metal such as Y (yttrium), Gd (gadolinium), Sm (samarium), and Ho (holmium), etc.), Ba, and Cu in a ratio of about 1:2:3, etc. can be used.

[0041] Then, as in Fig. 4B shows the pre-firing step for removing the organic components contained in the applied MOD solution. For the pre-firing step, the connecting end of the superconducting wires 10a, 10b is heat-treated in an N2+O2 gas atmosphere at a temperature range of 400°C to 500°C, more preferably at 500°C. As a result, a deposition layer 40 corresponding to the superconducting conductor layer 8 to be connected is formed in the rectangular removal sections on the respective connecting end side of the superconducting conductor layer 3 of the superconducting wires 10a, 10b.

[0042] Thereafter, a layered structure is formed by the superconducting wire 10a, as shown in Fig. 4C, the deposition layers 40, 40 of the superconducting wires 10a, 10b are turned over, and the deposition layers 40, 40 of the superconducting wires 10a, 10b are facing each other, and the deposition layers 40, 40 are tightly bonded to each other by positional adjustment. Furthermore, two protective materials 7 are prepared, to which the metal portions 9 have been bonded in advance at desired positions, with these two protective materials 7, 7 centering the layered structure. Subsequently, the main firing step is performed by the MOD method by heating the connecting ends of the superconducting wires 10a, 10b containing the deposition layers 40 while applying pressure in the thickness direction via the protective materials 7. For the main firing step, the connecting end of the superconducting wires 10a, 10b is preferably heat-treated in an Ar+O2 gas atmosphere in a temperature range of 760°C to 800°C.As a result, epitaxial growth (crystallization) occurs while the deposition layer 40 of the superconducting wire 10a and the deposition layer 40 of the superconducting wire 10b are tightly bonded to each other, and a one-piece superconducting conductor layer 8 to be bonded is formed. Furthermore, the metal portions 9, 9 provided at opposite positions of the protective materials 7, 7, respectively, are integrally bonded to each other, and the two protective materials 7, 7 are bonded together in a state where mutual attractive forces act in the direction centering the superconducting wires 10a, 10b.

[0043] Furthermore, after the main firing step, an oxygen annealing step is performed, in which the superconducting conductor layer 8 to be connected is doped with oxygen. During this oxygen annealing treatment, the connecting ends of the superconducting wires 10a, 10b are placed in an oxygen atmosphere and heated to a specific temperature. As a concrete example, the area to be treated with oxygen annealing is left in an oxygen atmosphere with a temperature range of 350°C to 500°C and doped with oxygen under these conditions. The superconducting conductor layer 8 to be connected is formed over the entire width direction of the superconducting wires 10a, 10b.Since the end faces of the superconducting conductor layer 8 to be connected are exposed on the side surfaces of both sides in the width direction of the superconducting wires 10a, 10b, oxygen doping can be effectively performed starting from these exposed end faces. In this way, the structure shown in FIG. Fig. The connection structure 20 shown in Figure 4D is produced.

[0044] As mentioned above, the connection structure obtained by the manufacturing method of the present invention has high connection strength and can improve the yield of the connection structure 20. (Second embodiment)

[0045] Fig. 5 is a schematic cross-section of the connecting structure according to a second embodiment of the present invention. Fig. The interconnection structure 20A shown in Figure 5 forms an interconnection structure in which the two superconducting wires 10a, 10b are superimposed and extend in the same direction. Even with such an interconnection structure in which the two superconducting wires 10a, 10b extend in the same direction, the superconducting wires 10a, 10b are interconnected with high interconnection strength. This can suppress the occurrence of separation between the superconducting wires 10a, 10b at the superconducting interconnection portion C, and improve the yield of the interconnection structure 20A. Furthermore, the superconducting interconnection portion C can be effectively protected from the outside world. (Third embodiment)

[0046] Fig. 6 is a schematic cross-sectional view of a connecting structure 20B according to a third embodiment of the present invention. Since, in the illustrated connecting structure 20B, the ends of the superconducting wires 10a, 10b are connected to each other by the superconducting conductor layer 8 to be connected, forming the superconducting connecting portion C, and the two protective materials 7, 7 are arranged on the side of the base material (not shown) of the superconducting wires 10a, 10b, a structure with a curvature is created, making it particularly suitable for use inside a coil. Although the degree of curvature varies depending on the bending strength of the components, such as the superconducting wires 10a, 10b, the protective materials 7, etc., it can be suitably designed to a degree that does not affect the respective components. Fig. The superconducting wires 10a, 10b shown in Figure 6 are constructed from the base material 1, the intermediate layer 2, the superconducting conductor layer 3, and the metal protective layer 4, with the detailed layer structure omitted. By providing such a curvature, the formation of separation between the superconducting wires 10a, 10b at the superconducting connection portion C in a coil can be suppressed, and the yield of the fabrication of the connection structure 20B can be improved. Furthermore, the superconducting connection portion C can be effectively protected from the outside world. (Fourth embodiment)

[0047] Fig. 7 is a perspective view of a connecting structure 20C according to a fourth embodiment of the present invention. As shown in Fig. 7, in the fourth embodiment, a case is shown in which a protective material 7a is not a flat plate, but the plate is bent in cross section into a hat shape to have a width greater than the width of the superconducting wires 10a, 10b extending in the length direction at the central portion in the width direction W, and has a concave step portion 11 into which the ends of the superconducting wires 10a, 10b are received.Then, the two protective materials 7a are arranged such that the concave step portions 11, 11 face each other and are aligned with each other, the superconducting connection portion C is centered from above and below by the two concave step portions 11, 11, and the four corner portions of the protective materials 7a, 7a, which are the portions surrounding the superconducting connection portion C further outward in the width direction than the concave step portions 11, are connected by means of the metal portions 9. Even with such a structure, the generation of separation between the superconducting wires 10a, 10b at the superconducting connection portion C can be suppressed, and the yield of the manufacturing of the connection structure 20C can be improved. Furthermore, the superconducting connection portion C can be effectively protected from the outside. (Fifth embodiment)

[0048] Fig. 8A is a plan view of a connecting structure 20D according to a fifth embodiment of the present invention. The illustrated connecting structure 20D shows a case where a metal portion 9a is formed over the entire width direction at both ends of the length direction L of the protective material 7. In Fig. 8 shows the section of an area R1 (area that is in Fig. 8 is surrounded by a dashed line) the area in which the metal section 9a is formed. Here, the metal section 9a, as shown in Fig. 8B, the connecting portion 20D has an arcuate cross-sectional shape so that it comes into contact with the base material 1 but not with the superconducting conductor layer 3 or the metal protective layer 4 covering the superconducting conductor layer 3. When manufacturing the connecting structure 20D of such a structure, oxygen supplied from the arrow directions A can also be supplied into the interior of the connecting structure 20D through a gap G (not shown) provided between the two protective materials 7, 7. Furthermore, the fifth embodiment has the advantage of enabling stronger attachment since the metal portions 9a are in contact with the base material 1. (Sixth Embodiment)

[0049] Fig. Fig. 9 is a perspective view of a connecting structure 20E according to a sixth embodiment of the present invention. The illustrated connecting structure 20E shows a case where metal portions 9b are formed between two protective materials 7, 7 over the entire length direction at both ends of the width direction W thereof. Fig. 9 shows the section of an area R2 (area which is in Fig. 9 is surrounded by a dashed line) the area in which the metal sections 9b are formed. During the manufacture of the connecting structure 20E of such a structure, oxygen can be supplied via the gap G between the metal sections 9b and the superconducting wires 10a, 10b. (Seventh Embodiment)

[0050] Fig. 10 is a perspective view of an interconnection structure 20F according to a seventh embodiment of the present invention. The point that metal portions 9c are formed over the entire length direction at both ends of the width direction W of the protective material 7b is the same as in the fifth embodiment, while a difference is that oxygen supply holes h for supplying oxygen are further provided in the metal portions 9c, extending from the outer surface of the metal portions 9c to the inner surface. This allows oxygen to be supplied not only via the gap G between the metal portions 9c and the superconducting wires 10a, 10b, but also via the oxygen supply holes h during fabrication of the interconnection structure.

[0051] As mentioned above, connection structures according to the above embodiments have been described, but the present invention is not limited to the above embodiments, but various modifications and changes are possible based on the technical spirit of the present invention.

[0052] In order to prevent oxidation of the metal due to contact with air, the connecting structure 20 according to the present invention may also have a resin such as epoxy resin filled into the space portion. [List of reference symbols] 1 base material 2 Intermediate layer 3 superconducting conductor layer 4 Metal protective layer 7, 7a, 7b Protective materials 8 superconducting conductor layer to be connected 9, 9a, 9b, 9c metal sections 10 superconducting wire 10a first superconducting wire 10b second superconducting wire 11 concave step area 20, 20A, 20B, 20C, 20D, 20E, 20F connection structures 30 MOD solution 40 deposition layer C superconducting connection section G space< / verbindungsstruktur>

Claims

[1] Connection structure (20) comprising: a first and a second superconducting wire (10a, 10b), which are two superconducting wires comprising a strip-shaped base material (1), an intermediate layer (2) formed on the base material (1), and a superconducting conductor layer (3) formed on the intermediate layer (2), a connecting superconducting conductor layer (8) which connects the first and second superconducting wires (10a, 10b) in a positional relationship in which the surfaces of the superconducting conductor layers (3) face each other, and together with the first and second superconducting wires (10a, 10b) forms a superconducting connecting section (C), two protective materials (7, 7) arranged on the respective sides of the base materials (1) of the first and second superconducting wires (10a, 10b) in a positional relationship in which they clamp and cover the superconducting connecting portion (C), and which are wider than the first and second superconducting wires (10a, 10b), and Metal sections (9) made of fusible material and connecting the two protective materials (7) to each other, wherein the metal sections (9) are formed on the inner surfaces of the two protective materials (7, 7) at locations along the superconducting wires (10a, 10b) where the superconducting connecting section (C) is not positioned. [2] The interconnection structure (20) according to claim 1, wherein the first and second superconducting wires (10a, 10b) each further comprise a metal protective layer (4) covering the superconducting conductor layer (3) over the entire area except for the superconducting interconnection portion (C). [3] The connecting structure (20) according to claim 1 or 2, wherein the metal portions (9) are provided at at least four locations surrounding the superconducting connecting portion (C). [4] Connecting structure (20) according to one of claims 1 to 3, wherein the metal sections (9) are a metal or an alloy containing at least Ag, Au and / or Cu. [5] The connecting structure (20) according to any one of claims 1 to 4, wherein the difference between the elastic coefficient of the base material (1) and the elastic coefficient of the protective materials (7) is in a range of less than or equal to 80 GPa. [6] The connecting structure (20) according to any one of claims 1 to 5, wherein the elastic coefficient of the protective materials (7) is 150 GPa to 250 GPa. [7] Connecting structure (20) according to one of claims 1 to 6, wherein the melting point of the protective materials (7) is greater than or equal to 1000°C. [8] Connecting structure (20) according to one of claims 1 to 7, wherein the thickness of the protective materials (7) is 30 µm to 300 µm. [9] Connecting structure (20) according to one of claims 1 to 8, wherein the protective materials (7) are a Ni-based alloy, stainless steel or carbon steel.

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