JP6178779B2 - Superconducting wire connection structure and manufacturing method of superconducting wire connection structure - Google Patents

Superconducting wire connection structure and manufacturing method of superconducting wire connection structure Download PDF

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JP6178779B2
JP6178779B2 JP2014246782A JP2014246782A JP6178779B2 JP 6178779 B2 JP6178779 B2 JP 6178779B2 JP 2014246782 A JP2014246782 A JP 2014246782A JP 2014246782 A JP2014246782 A JP 2014246782A JP 6178779 B2 JP6178779 B2 JP 6178779B2
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駿 栗原
駿 栗原
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Description

本発明は、超電導線材の接続構造体および超電導線材の接続構造体の製造方法に関する。   The present invention relates to a superconducting wire connecting structure and a method of manufacturing a superconducting wire connecting structure.

近年、超電導線材として、Ｂｉ２２１２（Ｂｉ２Ｓｒ２ＣａＣｕ２Ｏ８＋δ）、Ｂｉ２２２３（Ｂｉ２Ｓｒ２Ｃａ２Ｃｕ３Ｏ１０＋δ）等のビスマス系超電導線材や、ＲＥ１２３（ＲＥＢａ２Ｃｕ３Ｏ７−δ、ＲＥ：希土類元素、例えばイットリウム）等のイットリウム系超電導線材といった、酸化物超電導線材の開発が進められている。酸化物超電導線材としては、テープ状に形成されたものが知られている。 Recently, a superconducting wire, Bi2212 (Bi 2 Sr 2 CaCu 2 O 8 + δ), Bi2223 (Bi 2 Sr 2 Ca 2 Cu 3 O 10 + δ) bismuth based superconducting wires, such as material or, RE123 (REBa 2 Cu 3 O 7-δ, Development of oxide superconducting wires such as yttrium-based superconducting wires such as RE: rare earth elements (for example, yttrium) is underway. As the oxide superconducting wire, one formed in a tape shape is known.

このような超電導線材同士を接続する技術として、超電導層の上に成膜された保護層や安定化層同士を半田接合する方法が知られている。保護層や安定化層同士で接合した場合には、接続部に電気抵抗が生じるため、発熱により臨界電流値Ｉｃの不安定となるといった問題があった。また、接続部に電気抵抗を生じるため、電力貯蔵装置のような永久電流モードを必要とする装置に適用できないという問題があった。   As a technique for connecting such superconducting wires, a method is known in which a protective layer and a stabilization layer formed on a superconducting layer are soldered together. When the protective layer and the stabilization layer are bonded to each other, an electrical resistance is generated at the connection portion, and thus there is a problem that the critical current value Ic becomes unstable due to heat generation. In addition, since electrical resistance is generated in the connection portion, there is a problem that it cannot be applied to a device such as a power storage device that requires a permanent current mode.

一方で、特許文献１には、超電導層同士を、超電導接合膜を介し接合することでこのような問題を解決する技術が記載されている。この技術では、超電導層同士の間に、超電導体を構成する金属を含む溶液の膜を形成し、加熱処理することにより、超電導接合膜を形成して超電導層同士を接合している。   On the other hand, Patent Document 1 describes a technique for solving such a problem by joining superconducting layers to each other via a superconducting bonding film. In this technique, a film of a solution containing a metal constituting the superconductor is formed between the superconducting layers, and heat treatment is performed to form a superconducting bonding film to join the superconducting layers.

特開２０１３−２３５６９９号公報JP 2013-235699 A

特許文献１に記載の超電導接合膜は、有機金属塗布熱分解法（Metal Organic Deposition、以下ＭＯＤ法）により形成されている。ＭＯＤ法は、溶液から前駆体を経て結晶化して超電導接合膜を形成する成膜方法であり、異相を析出しやすいことが知られている。一例として超電導体として、ＧｄＢａ２Ｃｕ３Ｏ７−δ（以下、ＧｄＢＣＯ）を用いた場合には、超電導接合膜に異相であるＧｄ２ＢａＣｕＯ５が析出する。異相は、超電導特性を有さないために、異相が析出すると接続部の臨界電流密度Ｊｃが低下するという問題があった。 The superconducting bonding film described in Patent Document 1 is formed by an organic metal coating pyrolysis method (hereinafter referred to as MOD method). The MOD method is a film forming method in which a superconducting bonding film is formed by crystallization from a solution via a precursor, and it is known that foreign phases are easily precipitated. As an example, when GdBa 2 Cu 3 O 7-δ (hereinafter, GdBCO) is used as a superconductor, Gd 2 BaCuO 5, which is a different phase, is deposited on the superconducting junction film. Since the heterogeneous phase does not have superconducting characteristics, there is a problem that the critical current density Jc of the connection portion decreases when the heterogeneous phase precipitates.

本発明は、以上のような実情に鑑みなされたものであり、電気抵抗の発生と臨界電流密度Ｊｃの低下を十分に抑制した超電導線材の接続構造体の提供を目的の一つとする。   The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a superconducting wire connecting structure in which generation of electrical resistance and reduction in critical current density Jc are sufficiently suppressed.

上記課題を解決するため、本発明の超電導線材の接続構造体の一実施態様は、耐熱性の金属からなる基材と、前記基材の一方の面側に位置する超電導層と、前記超電導層の一方の面に位置するＡｇ又はＡｇ合金からなる保護層と、を有し、前記超電導層の少なくとも一部が前記保護層から露出した状態で厚さ方向に互いに対向して配置されたテープ状の一対の超電導線材と、厚さ方向に対向して配置された前記超電導層同士を接合する接合層と、を備え、前記接合層が、粒状体が焼結されてなる多孔質の超電導体であり、前記接合層が、前記保護層と接触して隣接し、前記超電導層の厚さが、０．５μｍ以上５μｍ以下である。
また、本発明の超電導線材の接続構造体の一実施態様は、超電導層を有し、前記超電導層の少なくとも一部が厚さ方向に互いに対向して配置されたテープ状の一対の超電導線材と、厚さ方向に対向して配置された前記超電導層同士を接合する接合層と、を備え、前記接合層が、粒状体が焼結されてなる多孔質の超電導体である。
この構成によれば、超電導体の粒状体を焼結することで形成した接合層により、超電導層同士を接合できる。接合層は超電導特性もつため、接続構造体は、接続部において電気抵抗が生ずることを十分に抑制できる。また、接合層は、組成比の整った粒状体を基に形成できるために、異相が析出することがなく、臨界電流密度Ｊｃを高めることができる。 In order to solve the above problems, an embodiment of a connection structure of a superconducting wire according to the present invention includes a base material made of a heat-resistant metal, a superconducting layer located on one surface side of the base material, and the superconducting layer. has a protective layer made of Ag or Ag alloy is located on the surface of the hand of the tape at least a portion of the superconducting layer is arranged to face each other in the thickness direction in a state of being exposed from the protective layer A pair of superconducting wires having a shape and a joining layer that joins the superconducting layers arranged facing each other in the thickness direction, and the joining layer is a porous superconductor formed by sintering a granular material The bonding layer is in contact with and adjacent to the protective layer, and the thickness of the superconducting layer is not less than 0.5 μm and not more than 5 μm .
Further, one embodiment of the connection structure of the superconducting wire of the present invention includes a pair of tape-shaped superconducting wires having a superconducting layer, wherein at least a part of the superconducting layer is disposed to face each other in the thickness direction. And a joining layer that joins the superconducting layers arranged to face each other in the thickness direction, and the joining layer is a porous superconductor formed by sintering a granular material.
According to this configuration, the superconducting layers can be joined to each other by the joining layer formed by sintering the superconductor granules. Since the bonding layer has superconducting properties, the connection structure can sufficiently suppress the occurrence of electrical resistance at the connection portion. Further, since the bonding layer can be formed on the basis of a granular material having a uniform composition ratio, a heterogeneous phase does not precipitate and the critical current density Jc can be increased.

上記の超電導線材の接続構造体は、前記接合層が設けられた接続部を含む超電導線材の外周が金属テープにより覆われていてもよい。
この構成によれば、接続構造体の外周を金属テープで覆うことで、接続部の強度を高めることができる。 In the superconducting wire connecting structure described above, the outer periphery of the superconducting wire including the connecting portion provided with the bonding layer may be covered with a metal tape.
According to this structure, the intensity | strength of a connection part can be raised by covering the outer periphery of a connection structure with a metal tape.

上記の超電導線材の接続構造体は、前記超電導層と前記接合層との組成が同じであってもよい。
この構成によれば、接合層と超電導層との界面で超電導体の結晶同士を結合させ接合強度を高めることができる。また、同じ組成の超電導体を用いることで、接合層と超電導層との臨界温度を同じとすることができ、接続構造体の温度の制御を複雑に行う必要がない。 In the superconducting wire connecting structure, the superconducting layer and the bonding layer may have the same composition.
According to this configuration, it is possible to bond the superconductor crystals at the interface between the bonding layer and the superconducting layer to increase the bonding strength. In addition, by using superconductors having the same composition, the critical temperatures of the bonding layer and the superconducting layer can be made the same, and it is not necessary to control the temperature of the connection structure in a complicated manner.

また、超電導線材の接続構造体に係る製造方法は、耐熱性の金属からなる基材と、前記基材の一方の面側に位置する超電導層と、前記超電導層の一方の面に位置するＡｇ又はＡｇ合金からなる保護層と、を有する一対の超電導線材を用意し、一対の前記超電導線材の前記保護層の一部をエッチングにより除去し、前記超電導層を露出させ、一対の前記超電導線材の前記超電導層の前記保護層から露出した部分を厚さ方向に対向させ、超電導層同士の間にバインダと混合した状態で超電導体の粒状体を塗布するとともに一対の前記超電導線材を重ね合わせ、一対の前記超電導線材を介して前記粒状体に２．５Ｎ／ｃｍ２ の負荷を加えた状態で、５００℃、２４時間で脱脂し、さらに９５０℃、１６時間で加熱することで前記粒状体を焼結し、超電導体からなる多孔質の接合層を形成する。
この構成によれば、超電導層同士の間に粒状体を配置して加圧、加熱することで、超電導層と接合された超電導体からなる接合層を形成できる。また、組成比の整った粒状体を用いることができるため、接合層の超電導体に異相が生じることを抑制できる。 The manufacturing method according to the connection structure of the superconducting wire includes a substrate formed of a heat-resistant metal, and the superconducting layer located on one surface side of the substrate, located on the surface of the hand of the superconducting layer A pair of superconducting wires having a protective layer made of Ag or an Ag alloy is prepared, a part of the protective layer of the pair of superconducting wires is removed by etching, the superconducting layer is exposed, and the pair of superconducting wires The portion exposed from the protective layer of the superconducting layer is opposed in the thickness direction, and the superconducting granular material is applied in a state of being mixed with a binder between the superconducting layers, and a pair of the superconducting wires are overlapped, In a state where a load of 2.5 N / cm 2 is applied to the granular body through a pair of superconducting wires, the granular body is degreased at 500 ° C. for 24 hours and further heated at 950 ° C. for 16 hours. Sintered and super A porous bonding layer made of an electric conductor is formed.
According to this structure, the joining layer which consists of a superconductor joined to the superconducting layer can be formed by disposing the granular material between the superconducting layers and applying pressure and heating. Moreover, since a granular material with a uniform composition ratio can be used, it is possible to suppress the occurrence of a different phase in the superconductor of the bonding layer.

上記の超電導線材の接続構造体の製造方法は、前記粒状体を、焼結により分解されるバインダと混合した状態で塗布してもよい。
粒状体とバインダとを混合して超電導層に塗布することで、粒状体が飛散しにくくなり、超電導層同士の間に粒状体を確実に配置して接合層を形成できる。また、バインダは焼結により分解されるため、接合層の超電導特性に悪影響を与えることがない。 In the manufacturing method of the connection structure of the superconducting wire, the granular material may be applied in a state of being mixed with a binder that is decomposed by sintering.
By mixing and applying the granular material and the binder to the superconducting layer, the granular material is less likely to be scattered, and the bonding layer can be formed by reliably arranging the granular material between the superconducting layers. Further, since the binder is decomposed by sintering, the superconducting property of the bonding layer is not adversely affected.

本発明の超電導線材の接続構造体によれば、電気抵抗の発生と臨界電流密度Ｊｃの低下を十分に抑制できる。また、接続構造体は、永久電流モードを必要とする超電導機器に採用できる。   According to the superconducting wire connecting structure of the present invention, it is possible to sufficiently suppress the generation of electrical resistance and the decrease in critical current density Jc. Further, the connection structure can be employed in superconducting equipment that requires a permanent current mode.

接続構造体の第１実施形態を示す断面模式図である。It is a cross-sectional schematic diagram which shows 1st Embodiment of a connection structure. 接続構造体の第２実施形態を示す断面模式図である。It is a cross-sectional schematic diagram which shows 2nd Embodiment of a connection structure. ビスマス系の超電導線材の一例構造を示す断面図である。It is sectional drawing which shows an example structure of a bismuth-type superconducting wire. 実施例における臨界電流密度の測定方法を示す模式図である。It is a schematic diagram which shows the measuring method of the critical current density in an Example.

以下、超電導線材の接続構造体の実施形態について図面に基づいて説明する。なお、以下の説明で用いる図面は、特徴をわかりやすくするために、便宜上特徴となる部分を拡大して示している場合があり、各構成要素の寸法比率などが実際と同じであるとは限らない。また、本発明は以下の実施形態に限定されるものではない。
本明細書中の各図において、線材の幅方向をＸ方向、長手方向をＹ方向、厚さ方向をＺ方向とする。 Hereinafter, an embodiment of a superconducting wire connecting structure will be described with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent. The present invention is not limited to the following embodiment.
In each figure in this specification, the width direction of the wire is the X direction, the longitudinal direction is the Y direction, and the thickness direction is the Z direction.

＜第１実施形態＞
第１実施形態の超電導線材の接続構造体（以下、接続構造体）３０について説明する。
図１は、接続構造体３０を示す断面模式図である。接続構造体３０は、酸化物超電導層（超電導層）１２を有する一対の酸化物超電導線材（超電導線材）１を接続部５において接続した構造を有する。接続構造体３０は、一対の酸化物超電導線材１と、一対の酸化物超電導線材１の酸化物超電導層１２同士を接合する接合層１４と、を有する。 <First Embodiment>
A superconducting wire connecting structure (hereinafter referred to as a connecting structure) 30 according to the first embodiment will be described.
FIG. 1 is a schematic cross-sectional view showing the connection structure 30. The connection structure 30 has a structure in which a pair of oxide superconducting wires (superconducting wires) 1 having an oxide superconducting layer (superconducting layer) 12 are connected at a connecting portion 5. The connection structure 30 includes a pair of oxide superconducting wires 1 and a bonding layer 14 that joins the oxide superconducting layers 12 of the pair of oxide superconducting wires 1.

本実施形態において接続される酸化物超電導線材（超電導線材）１について説明する。
本実施形態では、酸化物超電導線材１として、イットリウム系酸化物超電導線材を例示する。酸化物超電導線材１は、テープ状の基材１０に、中間層１１と酸化物超電導層１２と保護層１３とが、積層された構造を有する。保護層１３は、酸化物超電導線材１の端部１ａ近傍であって、接合層１４が形成される領域には設けられていない。 The oxide superconducting wire (superconducting wire) 1 connected in the present embodiment will be described.
In this embodiment, an yttrium-based oxide superconducting wire is exemplified as the oxide superconducting wire 1. The oxide superconducting wire 1 has a structure in which an intermediate layer 11, an oxide superconducting layer 12, and a protective layer 13 are laminated on a tape-like base material 10. The protective layer 13 is not provided in the vicinity of the end 1a of the oxide superconducting wire 1 and in the region where the bonding layer 14 is formed.

基材１０は、酸化物超電導線材１の基材として使用し得るものであれば良く、耐熱性の金属からなるものが好ましい。基材１０は、耐熱性の金属の中でも、合金が好ましく、ニッケル（Ｎｉ）合金又は銅（Ｃｕ）合金がより好ましい。なかでも、市販品であればハステロイ（商品名、ヘインズ社製）が好適であり、モリブデン（Ｍｏ）、クロム（Ｃｒ）、鉄（Ｆｅ）、コバルト（Ｃｏ）等の成分量が異なる、ハステロイＢ、Ｃ、Ｇ、Ｎ、Ｗ等の何れの種類も使用できる。また、基材１０として、金属結晶の配向をそろえた配向基板を用いても良い。
本実施形態においては、基材１０の形状は、長尺のテープ形状であるが、例えば、シート形状であっても良い。基材１０の厚みは、目的に応じて適宜調整すれば良く、１０〜５００μｍの範囲とすることができる。 The base material 10 may be any material that can be used as a base material for the oxide superconducting wire 1, and is preferably made of a heat-resistant metal. The base material 10 is preferably an alloy among heat resistant metals, and more preferably a nickel (Ni) alloy or a copper (Cu) alloy. Among them, Hastelloy (trade name, manufactured by Haynes Co., Ltd.) is suitable for commercial products, and has different amounts of components such as molybdenum (Mo), chromium (Cr), iron (Fe), cobalt (Co), etc. Any type of C, G, N, W, etc. can be used. Further, as the base material 10, an alignment substrate in which the alignment of metal crystals is aligned may be used.
In this embodiment, the shape of the base material 10 is a long tape shape, but may be a sheet shape, for example. What is necessary is just to adjust the thickness of the base material 10 suitably according to the objective, and it can be set as the range of 10-500 micrometers.

中間層１１は、基材１０の主面上に形成される。中間層１１は、下地層と、配向層およびキャップ層がこの順に積層された構造を適用することができる。下地層は、拡散防止層およびベッド層の何れか一方又は両方からなる。   The intermediate layer 11 is formed on the main surface of the substrate 10. As the intermediate layer 11, a structure in which an underlayer, an alignment layer, and a cap layer are stacked in this order can be applied. The underlayer is composed of one or both of a diffusion prevention layer and a bed layer.

拡散防止層は、この層よりも上面に他の層を形成する際に加熱処理した結果、基材１０や他の層が熱履歴を受ける場合に、基材１０の構成元素の一部が拡散し、不純物として酸化物超電導層１２側に混入することを抑制する機能を有する。拡散防止層は、Ｓｉ３Ｎ４、Ａｌ２Ｏ３、ＧＺＯ（Ｇｄ２Ｚｒ２Ｏ７）等から構成され、例えば厚み１０〜４００ｎｍに形成される。
ベッド層は、基材１０と酸化物超電導層１２との界面における構成元素の反応を抑え、この層よりも上面に設ける層の配向性を向上させるために設けられる。ベッド層は、界面反応性を低減し、その上に形成される膜の配向性を得るため層であり、Ｙ２Ｏ３、Ｅｒ２Ｏ３、ＣｅＯ２、Ｄｙ２Ｏ３、Ｅｒ２Ｏ３、Ｅｕ２Ｏ３、Ｈｏ２Ｏ３、Ｌａ２Ｏ３等からなり、その厚みは例えば１０〜１００ｎｍである。
配向層は、その上に形成されるキャップ層や酸化物超電導層１２の結晶配向性を制御するために設けられる。配向層は、その上のキャップ層の結晶配向性を制御するために２軸配向する物質から形成される。配向層の材質としては、Ｇｄ２Ｚｒ２Ｏ７、ＭｇＯ、ＺｒＯ２−Ｙ２Ｏ３（ＹＳＺ）、ＳｒＴｉＯ３、ＣｅＯ２、Ｙ２Ｏ３、Ａｌ２Ｏ３、Ｇｄ２Ｏ３、Ｚｒ２Ｏ３、Ｈｏ２Ｏ３、Ｎｄ２Ｏ３等の金属酸化物を例示することができる。この配向層はＩＢＡＤ（Ion-Beam-Assisted Deposition）法で形成することが好ましい。
キャップ層は、酸化物超電導層１２の結晶配向性を配向層と同等ないしそれ以上に強く制御するために設けられる。キャップ層は、上述の配向層の表面に成膜されて結晶粒が面内方向に自己配向し得る材料からなり、具体的には、ＣｅＯ２、Ｙ２Ｏ３、Ａｌ２Ｏ３、Ｇｄ２Ｏ３、ＺｒＯ２、ＹＳＺ、Ｈｏ２Ｏ３、Ｎｄ２Ｏ３、ＬａＭｎＯ３等からなる。キャップ層の膜厚は５０〜５０００ｎｍの範囲に形成できる。 As a result of heat treatment when forming another layer on the upper surface of this layer, the diffusion preventing layer diffuses part of the constituent elements of the base material 10 when the base material 10 or other layers receive a thermal history. And it has a function which suppresses mixing into the oxide superconducting layer 12 side as an impurity. The diffusion prevention layer is made of Si 3 N 4 , Al 2 O 3 , GZO (Gd 2 Zr 2 O 7 ), etc., and is formed to a thickness of 10 to 400 nm, for example.
The bed layer is provided to suppress the reaction of the constituent elements at the interface between the base material 10 and the oxide superconducting layer 12 and to improve the orientation of the layer provided on the upper surface than this layer. The bed layer is a layer for reducing the interfacial reactivity and obtaining the orientation of the film formed thereon. Y 2 O 3 , Er 2 O 3 , CeO 2 , Dy 2 O 3, Er 2 O 3 , Eu 2 O 3 , Ho 2 O 3 , La 2 O 3, etc., and the thickness is, for example, 10 to 100 nm.
The orientation layer is provided to control the crystal orientation of the cap layer and the oxide superconducting layer 12 formed thereon. The orientation layer is formed from a biaxially oriented material in order to control the crystal orientation of the cap layer thereon. The material of the alignment layer, Gd 2 Zr 2 O 7, MgO, ZrO 2 -Y 2 O 3 (YSZ), SrTiO 3, CeO 2, Y 2 O 3, Al 2 O 3, Gd 2 O 3, Zr 2 Examples thereof include metal oxides such as O 3 , Ho 2 O 3 , and Nd 2 O 3 . This alignment layer is preferably formed by an IBAD (Ion-Beam-Assisted Deposition) method.
The cap layer is provided in order to strongly control the crystal orientation of the oxide superconducting layer 12 to be equal to or higher than that of the alignment layer. The cap layer is formed on the surface of the above-described alignment layer and is made of a material that allows crystal grains to self-orient in the in-plane direction. Specifically, CeO 2 , Y 2 O 3 , Al 2 O 3 , Gd 2 O 3, ZrO 2, YSZ, Ho 2 O 3, Nd 2 O 3, consist of LaMnO 3 like. The film thickness of the cap layer can be formed in the range of 50 to 5000 nm.

酸化物超電導層１２は酸化物超電導体として公知のもので良く、具体的には、ＲＥ−１２３系と呼ばれるＲＥＢａ２Ｃｕ３Ｏ７−δ（ＲＥは希土類元素であるＳｃ、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕのうちの１種又は２種以上を表す）を例示できる。この酸化物超電導層１２として、Ｙ１２３（ＹＢａ２Ｃｕ３Ｏ７−δ）又はＧｄ１２３（ＧｄＢａ２Ｃｕ３Ｏ７−δ）などを例示できる。
酸化物超電導層１２の厚みは、０．５〜５μｍ程度であって、均一な厚みであることが好ましい。 The oxide superconducting layer 12 may be a known oxide superconductor, and specifically, REBa 2 Cu 3 O 7-δ called RE-123 series (RE is a rare earth element such as Sc, Y, La, Ce). , Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are represented. Examples of the oxide superconducting layer 12 include Y123 (YBa 2 Cu 3 O 7-δ ) or Gd123 (GdBa 2 Cu 3 O 7-δ ).
The oxide superconducting layer 12 has a thickness of about 0.5 to 5 μm and preferably a uniform thickness.

酸化物超電導層１２は、パルスレーザー蒸着法（Pulsed Laser Deposition、以下ＰＬＤ法）により成膜できる。ＰＬＤ法は、レーザー光をターゲットに照射して叩き出され若しくは蒸発した構成粒子の噴流（プルーム）を中間層１１に向けることで、中間層１１上に酸化物超電導層１２を形成する方法である。
なお、酸化物超電導層１２は、ＰＬＤ法以外に、ＭＯＤ法により成膜しても良い。 The oxide superconducting layer 12 can be formed by a pulsed laser deposition method (hereinafter referred to as PLD method). The PLD method is a method in which the oxide superconducting layer 12 is formed on the intermediate layer 11 by directing a jet (plume) of constituent particles struck or evaporated by irradiating the target with laser light to the intermediate layer 11. .
The oxide superconducting layer 12 may be formed by a MOD method other than the PLD method.

ＰＬＤ法に用いるターゲットは、以下の工程により製造できる。
まず、製造目的とする酸化物超電導層１２の組成に応じた原料粉末を混合する。原料粉末としては、例えば希土類元素の酸化物粉末、Ｂａの炭酸塩粉末、Ｃｕの酸化物粉末を用いることができる。次に、この原料粉末の混合物を仮焼きし、さらに粉砕して粉砕粉を採取する。次に、粉砕粉とバインダを混合する。バインダとしては、ポリビニルブチラール（ＰＶＢ）を用いることができる。次に、例えば円盤状にプレス成形し、焼結してターゲットを得ることができる。 The target used for the PLD method can be manufactured by the following steps.
First, raw material powders corresponding to the composition of the oxide superconducting layer 12 to be manufactured are mixed. As the raw material powder, for example, rare earth oxide powder, Ba carbonate powder, Cu oxide powder can be used. Next, this mixture of raw material powders is calcined and further pulverized to collect pulverized powder. Next, the pulverized powder and the binder are mixed. Polyvinyl butyral (PVB) can be used as the binder. Next, for example, the target can be obtained by press forming into a disk shape and sintering.

保護層１３は、酸化物超電導層１２上であって、酸化物超電導線材１の端部１ａ近傍以外の領域に形成されている。保護層１３は、Ａｇ又はＡｇ合金などの良電導性からなり、酸化物超電導層１２との接触抵抗が低くなじみの良い層として形成される。保護層１３は、スパッタ法などの成膜法により積層されて、その厚さは、１〜３０μｍ程度とされる。
酸化物超電導線材１は、全長に亘って酸化物超電導層１２上に保護層１３を形成した後に、端部１ａ近傍の保護層１３を除去して、端部１ａ近傍の酸化物超電導層１２を露出させる。なお、保護層１３の成膜時に端部１ａ近傍をマスキングすることで、端部１ａ近傍に保護層１３を形成しない領域を設けても良い。 The protective layer 13 is formed on the oxide superconducting layer 12 in a region other than the vicinity of the end 1 a of the oxide superconducting wire 1. The protective layer 13 is made of a highly conductive material such as Ag or an Ag alloy, and is formed as a layer having a low contact resistance with the oxide superconducting layer 12 and a familiarity. The protective layer 13 is laminated by a film forming method such as a sputtering method, and the thickness thereof is about 1 to 30 μm.
After the oxide superconducting wire 1 has formed the protective layer 13 on the oxide superconducting layer 12 over the entire length, the protective layer 13 in the vicinity of the end 1a is removed, and the oxide superconducting layer 12 in the vicinity of the end 1a is removed. Expose. Note that a region where the protective layer 13 is not formed may be provided in the vicinity of the end 1a by masking the vicinity of the end 1a when the protective layer 13 is formed.

接続構造体３０は、接続部５において、一対の酸化物超電導線材１の端部１ａ近傍で露出する酸化物超電導層１２同士が対向して配置されている。対向する酸化物超電導層１２同士は、接合層１４により接合されている。
本実施形態において、一対の酸化物超電導線材１の層構成および各層の厚さ、並びに幅は、同じであるとするが、互いに異なるものであっても良い。 In the connection structure 30, the oxide superconducting layers 12 exposed in the vicinity of the end portions 1 a of the pair of oxide superconducting wires 1 are arranged to face each other in the connection portion 5. The opposing oxide superconducting layers 12 are joined together by a joining layer 14.
In the present embodiment, the layer configuration of the pair of oxide superconducting wires 1 and the thickness and width of each layer are the same, but they may be different from each other.

接合層１４は、多孔質の超電導体であり、超電導特性を有する。接合層１４を構成する超電導体としては、公知のものであればよいが、酸化物超電導層１２を構成する超電導体と同じイットリウム系の酸化物超電導体（ＲＥＢａ２Ｃｕ３Ｏ７−δ（ＲＥは希土類元素））とすることが好ましい。接合層１４の超電導体と酸化物超電導層１２の超電導体を、ともにイットリウム系の酸化物超電導体とすることで、接合層１４と酸化物超電導層１２とは、拡散接合され、接合強度が高くなる。接合層１４と酸化物超電導層１２は、ともにイットリウム系であれば、異なる組成であっても、拡散接合が可能である。
接合層１４の超電導体は、酸化物超電導層１２を構成する酸化物超電導体と同じ組成を有することが、より好ましい。同じ組成の超電導体を用いることで、接合層１４と酸化物超電導層１２との界面で超電導体の結晶同士が結合するため接合強度を高めることができる。また、同じ組成の超電導体を用いることで、接合層１４と酸化物超電導層１２との臨界温度を同じとすることができる。したがって、同温度で超電導特性を発現させることができ、接続構造体３０の温度の制御を複雑に行う必要がない。
また、接合層１４の超電導体は、イットリウム系の酸化物超電導体の他に、ビスマス系の酸化物超電導体、ＭｇＢ２などの超電導体であってもよい。 The bonding layer 14 is a porous superconductor and has superconducting properties. The superconductor constituting the bonding layer 14 may be a known superconductor, but the same yttrium-based oxide superconductor (REBa 2 Cu 3 O 7-δ (RE) as the superconductor constituting the oxide superconducting layer 12. Is preferably a rare earth element)). By using both the superconductor of the bonding layer 14 and the superconductor of the oxide superconducting layer 12 as an yttrium-based oxide superconductor, the bonding layer 14 and the oxide superconducting layer 12 are diffusion-bonded and have high bonding strength. Become. If both the bonding layer 14 and the oxide superconducting layer 12 are yttrium-based, diffusion bonding is possible even if they have different compositions.
It is more preferable that the superconductor of the bonding layer 14 has the same composition as the oxide superconductor constituting the oxide superconducting layer 12. By using superconductors having the same composition, the superconductor crystals are bonded to each other at the interface between the bonding layer 14 and the oxide superconducting layer 12, so that the bonding strength can be increased. Moreover, the critical temperature of the joining layer 14 and the oxide superconducting layer 12 can be made the same by using the superconductor of the same composition. Therefore, superconducting characteristics can be developed at the same temperature, and it is not necessary to control the temperature of the connection structure 30 in a complicated manner.
In addition to the yttrium oxide superconductor, the superconductor of the bonding layer 14 may be a bismuth oxide superconductor or a superconductor such as MgB 2 .

接合層１４は、粒状体が焼結されて形成されている。このため、接合層１４の内部には、焼結前の粒状体の粒径に由来する結晶粒が形成されている。接合層１４は、焼結されて形成されているため多孔質となっている。   The bonding layer 14 is formed by sintering a granular material. For this reason, crystal grains derived from the grain size of the granular material before sintering are formed in the bonding layer 14. The bonding layer 14 is porous because it is formed by sintering.

接続構造体３０の製造方法について説明する。
まず、酸化物超電導線材１を一対用意する。これらの一対の酸化物超電導線材１は、予め端部１ａ近傍において保護層１３が除去され酸化物超電導層１２が露出している。 A method for manufacturing the connection structure 30 will be described.
First, a pair of oxide superconducting wire 1 is prepared. In the pair of oxide superconducting wires 1, the protective layer 13 is previously removed in the vicinity of the end portion 1 a and the oxide superconducting layer 12 is exposed.

また、接合層１４を形成するための粒状体を用意する。粒状体としては、酸化物超電導層１２をＰＬＤ法により形成する際に用いた、ターゲットを粉砕して採取した粉末を用いることが好ましい。ターゲットは、原料粉に由来する組成比を有しており、組成比が安定している。ターゲットを粉砕して採取した粉末を用いることで、異相のない接合層１４を形成できる。
また、ターゲットを粉砕した粉末ではなく、ターゲットの製造工程において、原料粉末を仮焼き、粉砕して採取された粉砕粉を粒状体として用いても良い。
さらに、粒状体をバインダと混合して粒状体を含むペーストを得る。粒状体とバインダとを混合しペーストとすることで、粒状体が飛散しにくくなり、取扱いが容易となる。バインダとしては、ターゲットの製造と同様に、ＰＶＢを用いることができる。また、バインダは、エタノールなどの溶媒を適宜添加しペーストの粘度を調整してもよい。 In addition, a granular material for forming the bonding layer 14 is prepared. As the granular material, it is preferable to use a powder obtained by pulverizing a target, which is used when the oxide superconducting layer 12 is formed by the PLD method. The target has a composition ratio derived from the raw material powder, and the composition ratio is stable. By using the powder obtained by pulverizing the target, the bonding layer 14 having no different phase can be formed.
Further, instead of the powder obtained by pulverizing the target, pulverized powder obtained by calcining and pulverizing the raw material powder in the target manufacturing process may be used as the granular material.
Furthermore, the granular material is mixed with a binder to obtain a paste containing the granular material. By mixing the granular material and the binder to form a paste, the granular material is less likely to be scattered and easy to handle. As the binder, PVB can be used similarly to the production of the target. Further, the binder may adjust the viscosity of the paste by appropriately adding a solvent such as ethanol.

次に、粒状体を含むペーストを、一方の酸化物超電導線材１の露出する酸化物超電導層１２に塗布する。さらに、他方の酸化物超電導線材１の露出する酸化物超電導層１２を、ペーストが塗布された酸化物超電導層１２に重ね合わせる。これにより、一対の酸化物超電導線材１の酸化物超電導層１２を対向させ、酸化物超電導層１２同士の間に超電導体の粒状体を配置した状態となる。   Next, the paste containing the granular material is applied to the exposed oxide superconducting layer 12 of one oxide superconducting wire 1. Further, the exposed oxide superconducting layer 12 of the other oxide superconducting wire 1 is superposed on the oxide superconducting layer 12 coated with the paste. As a result, the oxide superconducting layers 12 of the pair of oxide superconducting wires 1 are opposed to each other, and the superconductor granules are arranged between the oxide superconducting layers 12.

次に、重ね合わされた一対の酸化物超電導線材１を治具で挟み込み、重ね合わせた部分を加圧し、加圧状態を保持したまま加熱して粒状体を焼結させる。これにより、酸化物超電導層１２同士を接合する接合層１４が形成される。焼結させることにより、ペーストに含まれるバインダは分解されため、接合層１４にバインダの成分は残留しない。したがって、接合層１４は、粒状体の組成をもつ超電導体となる。
なお、焼結を行う前に、一対の酸化物超電導線材を挟み込むように加圧した状態で、焼結温度より低い温度で、加熱しバインダを分解する脱脂工程を行っても良い。 Next, the pair of superposed oxide superconducting wires 1 are sandwiched between jigs, the overlapped portion is pressurized, and heated while maintaining the pressurized state to sinter the granular material. Thereby, the joining layer 14 which joins the oxide superconducting layers 12 is formed. By sintering, the binder contained in the paste is decomposed, so that no binder component remains in the bonding layer 14. Therefore, the bonding layer 14 becomes a superconductor having a granular composition.
In addition, before performing sintering, you may perform the degreasing process which heats at the temperature lower than sintering temperature and decomposes | disassembles a binder in the state pressurized so that a pair of oxide superconducting wire may be pinched | interposed.

本実施形態の接続構造体３０によれば、粒状体を焼結することで形成した超電導体からなる接合層１４により、酸化物超電導層同士が接合されている。接続構造体３０の接合層１４は、組成比の整った粒状体を焼結して形成できるために、異相が析出することがなく、接続部５における臨界電流密度Ｊｃの低下を抑制できる。
接続構造体３０は、上述のように電気特性に優れた超電導体を介して接続されているため、接続部５において電気抵抗が生じて発熱することを抑制し、熱による臨界電流値Ｉｃの不安定化を抑制できる。
また、接続構造体３０は、電気抵抗が生じることを十分に抑制しているため、永久電流モードを必要とする超電導機器に採用できる。 According to the connection structure 30 of the present embodiment, the oxide superconducting layers are bonded to each other by the bonding layer 14 made of a superconductor formed by sintering the granular material. Since the bonding layer 14 of the connection structure 30 can be formed by sintering a granular material having a uniform composition ratio, a heterogeneous phase does not precipitate, and a decrease in the critical current density Jc in the connection portion 5 can be suppressed.
Since the connection structure 30 is connected via the superconductor having excellent electrical characteristics as described above, it is possible to suppress the generation of heat due to the occurrence of electrical resistance in the connection portion 5 and to prevent the critical current value Ic from being reduced by heat. Stabilization can be suppressed.
In addition, since the connection structure 30 sufficiently suppresses the occurrence of electrical resistance, the connection structure 30 can be employed in a superconducting device that requires a permanent current mode.

＜第２実施形態＞
第２実施形態の接続構造体３１について説明する。
図２は、接続構造体３１を示す断面模式図である。第２実施形態の接続構造体３１は、の基本構造は、第１実施形態の接続構造体３０と同様である。接続構造体３１は、短尺の酸化物超電導線材１Ａが一対の酸化物超電導線材１を橋渡しするように配置されている。また、接続構造体３１は、接続部５を含む酸化物超電導線材１の外周が金属テープ１５により覆われている。
なお、上述の第１実施形態と同一態様の構成要素については、同一符号を付し、その説明を省略する。 Second Embodiment
The connection structure 31 of 2nd Embodiment is demonstrated.
FIG. 2 is a schematic cross-sectional view showing the connection structure 31. The basic structure of the connection structure 31 of the second embodiment is the same as that of the connection structure 30 of the first embodiment. The connection structure 31 is arranged so that the short oxide superconducting wire 1 </ b> A bridges the pair of oxide superconducting wires 1. In the connection structure 31, the outer periphery of the oxide superconducting wire 1 including the connection portion 5 is covered with the metal tape 15.
In addition, about the component of the same aspect as the above-mentioned 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

接続構造体３１は、一対の酸化物超電導線材１と短尺の酸化物超電導線材１Ａとを有する。一対の酸化物超電導線材１および短尺の酸化物超電導線材１Ａは、端部近傍において保護層１３が除去されている。
接続構造体３１において、一対の酸化物超電導線材１は、各層の積層方向が揃えられて、互いの端部同士が隙間を空けて配置されている。短尺の酸化物超電導線材１Ａは、一対の酸化物超電導線材１と同様の構成を有し、一対の酸化物超電導線材１を橋渡しするように配置されている。酸化物超電導線材１、１Ａの露出する酸化物超電導層１２同士は、互いに対向して配置されて、接合層１４により接合されている。 The connection structure 31 includes a pair of oxide superconducting wires 1 and a short oxide superconducting wire 1A. In the pair of oxide superconducting wires 1 and the short oxide superconducting wires 1A, the protective layer 13 is removed in the vicinity of the ends.
In the connection structure 31, the pair of oxide superconducting wires 1 are arranged such that the stacking directions of the respective layers are aligned, and the end portions thereof are spaced apart from each other. The short oxide superconducting wire 1 </ b> A has the same configuration as the pair of oxide superconducting wires 1 and is arranged so as to bridge the pair of oxide superconducting wires 1. The exposed oxide superconducting layers 12 of the oxide superconducting wires 1, 1 </ b> A are arranged facing each other and joined by a joining layer 14.

接続構造体３１の酸化物超電導線材１、１Ａの配置は、第１実施形態の接続構造体３０の接続部５を連続して配置したものであると説明できる。このような構造とすることで、接続部分の前後で酸化物超電導線材１の積層方向の逆転がない接続構造体３１を提供することができる。   The arrangement of the oxide superconducting wires 1 and 1A in the connection structure 31 can be described as a continuous arrangement of the connection portions 5 of the connection structure 30 of the first embodiment. By setting it as such a structure, the connection structure 31 which does not reverse the lamination direction of the oxide superconducting wire 1 before and after a connection part can be provided.

接続構造体３１は、外周が金属テープ１５により覆われた構造を有する。金属テープ１５は、接続部５を含む酸化物超電導線材１、１Ａの外周に配置されている。金属テープ１５と酸化物超電導線材１、１Ａの外周とは、半田１６により接合されている。   The connection structure 31 has a structure in which the outer periphery is covered with the metal tape 15. The metal tape 15 is disposed on the outer periphery of the oxide superconducting wire 1, 1 </ b> A including the connection portion 5. The metal tape 15 and the outer periphery of the oxide superconducting wire 1, 1 </ b> A are joined by solder 16.

金属テープ１５を構成する金属材料として、良導電性を有するものを用いた場合は、金属テープ１５は、事故時に発生する過電流をバイパスする役割を担う安定化層として機能する。良導電性を有する材料として、銅、黄銅（Ｃｕ−Ｚｎ合金）、Ｃｕ−Ｎｉ合金等の銅合金、ステンレス等の比較的安価な材質からなるものを用いることが好ましく、中でも高い導電性を有し、安価であることから銅製が好ましい。
また、接続構造体３１を超電導限流器に使用する場合においては、金属テープ１５に用いられる材料は、例えば、Ｎｉ−Ｃｒ等のＮｉ系合金等の高抵抗金属を用いる事が良い。 In the case where a material having good conductivity is used as the metal material constituting the metal tape 15, the metal tape 15 functions as a stabilization layer that plays a role of bypassing overcurrent generated at the time of an accident. As a material having good conductivity, a material made of a relatively inexpensive material such as copper, brass (Cu—Zn alloy), a copper alloy such as Cu—Ni alloy, stainless steel, etc. is preferably used. However, copper is preferable because it is inexpensive.
When the connection structure 31 is used for a superconducting fault current limiter, the material used for the metal tape 15 is preferably a high-resistance metal such as a Ni-based alloy such as Ni-Cr.

金属テープ１５の接合工程は、以下の手順により行う。
まず、一対の酸化物超電導線材１と短尺の酸化物超電導線材１Ａとを接合層１４により接合する。次に、接合層１４により接合した酸化物超電導線材１、１Ａを、メッキにより半田１６の層が形成された金属テープ１５の面上に配置する。さらに、金属テープ１５を横断面略Ｃ字型をなすように包み込んで折り曲げ加工し、半田１６を加熱溶融させてロールにより加圧する。以上の工程により、金属テープ１５を酸化物超電導線材１、１Ａの外周に接合できる。 The joining process of the metal tape 15 is performed according to the following procedure.
First, the pair of oxide superconducting wires 1 and the short oxide superconducting wire 1 </ b> A are joined by the joining layer 14. Next, the oxide superconducting wires 1 and 1A joined by the joining layer 14 are disposed on the surface of the metal tape 15 on which the solder 16 layer is formed by plating. Further, the metal tape 15 is wrapped and bent so as to have a substantially C-shaped cross section, and the solder 16 is heated and melted and pressed by a roll. Through the above steps, the metal tape 15 can be joined to the outer periphery of the oxide superconducting wire 1 or 1A.

第２実施形態の接続構造体３１は、第１実施形態と同様の効果を奏する上に、接続部５を含む酸化物超電導線材１、１Ａの外周に金属テープ１５が接合されていることにより、接続部５を補強して、強度を高めることができる。   The connection structure 31 of the second embodiment has the same effect as that of the first embodiment, and the metal tape 15 is bonded to the outer periphery of the oxide superconducting wire 1 and 1A including the connection portion 5. The connecting portion 5 can be reinforced to increase the strength.

以上に、本発明の実施形態を説明したが、実施形態における構成およびそれらの組み合わせ等は一例であり、本発明の趣旨から逸脱しない範囲内で、構成の付加、省略、置換、およびその他の変更が可能である。また、本発明は実施形態によって限定されることはない。   Although the embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments are examples, and additions, omissions, substitutions, and other modifications of the configurations are within the scope that does not depart from the spirit of the present invention. Is possible. Further, the present invention is not limited by the embodiment.

例えば、第１実施形態の接続構造体３０は、接続部５を含む酸化物超電導線材１の外周が、金属テープにより覆われるものであってもよい。   For example, in the connection structure 30 of the first embodiment, the outer periphery of the oxide superconducting wire 1 including the connection portion 5 may be covered with a metal tape.

また、上述の製造方法では、成膜した保護層１３を、酸化物超電導線材１の端部１ａ近傍で除去し酸化物超電導層１２を露出させている。保護層１３が成膜されていない酸化物超電導線材１同士を、接合層１４を介し接続し、後工程として保護層１３を成膜しても良い。   In the manufacturing method described above, the formed protective layer 13 is removed in the vicinity of the end 1a of the oxide superconducting wire 1 to expose the oxide superconducting layer 12. The oxide superconducting wires 1 on which the protective layer 13 is not formed may be connected to each other through the bonding layer 14, and the protective layer 13 may be formed as a post process.

また、各実施形態では、酸化物超電導線材１として、酸化物超電導層１２を備えたイットリウム系の超電導線材を用いる場合について説明した。超電導線材の種類は、これに限られるものではなく、図６に示すようなビスマス系の酸化物超電導線材（超電導線材）２００を採用しても良い。酸化物超電導線材２００は、ビスマス系の酸化物超電導体からなる酸化物超電導層２０１をＡｇのシース材２０２で被覆した状態となるようにロール圧延法などにより製造された構造となっている。
酸化物超電導線材２００を接合する場合は、端部近傍のシース材２０２をエッチング等により除去して、酸化物超電導層２０１を露出させた状態で、接合層１４により接合させる。
また、同様に、超電導線材は、ＭｇＢ２からなる超電導層を備えた超電導線材であっても良い。
さらに、接続する超電導線材同士は、異なる種類のものであっても良い。例えば、イットリウム系の酸化物超電導線材１とビスマス系の酸化物超電導線材２００とを接続するものであってもよい。また、イットリウム系の酸化物超電導線材１と、ＭｇＢ２からなる超電導層を備えた超電導線材とを接続するものであってもよい。 Moreover, in each embodiment, the case where the yttrium-type superconducting wire provided with the oxide superconducting layer 12 was used as the oxide superconducting wire 1 was demonstrated. The kind of superconducting wire is not limited to this, and a bismuth-based oxide superconducting wire (superconducting wire) 200 as shown in FIG. 6 may be adopted. The oxide superconducting wire 200 has a structure manufactured by a roll rolling method or the like so that an oxide superconducting layer 201 made of a bismuth-based oxide superconductor is covered with an Ag sheath material 202.
When the oxide superconducting wire 200 is joined, the sheath material 202 near the end is removed by etching or the like, and the oxide superconducting layer 201 is exposed and joined by the joining layer 14.
Similarly, the superconducting wire may be a superconducting wire provided with a superconducting layer made of MgB 2 .
Further, different types of superconducting wires may be connected. For example, the yttrium-based oxide superconducting wire 1 and the bismuth-based oxide superconducting wire 200 may be connected. Alternatively, the yttrium-based oxide superconducting wire 1 may be connected to a superconducting wire having a superconducting layer made of MgB 2 .

以下、実施例を示して本発明をさらに詳細に説明するが、本発明はこれらの実施例に限定されるものではない。
＜試料の作製＞
まず、ハステロイＣ−２７６（米国ヘインズ社商品名）からなる幅１０ｍｍ、厚み０．１ｍｍのテープ状の基材の表面を平均粒径３μｍのアルミナを使用し研磨した。次に、前記基材の表面をアセトンにより脱脂、洗浄した。
この基材の主面上にスパッタ法によりＡｌ２Ｏ３（拡散防止層；膜厚１００ｎｍ）を成膜し、その上に、イオンビームスパッタ法によりＹ２Ｏ３（ベッド層；膜厚３０ｎｍ）を成膜した。
次いで、このベッド層上に、イオンビームアシスト蒸着法（ＩＢＡＤ法）によりＭｇＯ（ＩＢＡＤ層；膜厚５〜１０ｎｍ）を形成し、その上にパルスレーザー蒸着法（ＰＬＤ法）により５００ｎｍ厚のＣｅＯ２（キャップ層）を成膜した。次いでＣｅＯ２層上にＰＬＤ法により２．０μｍ厚のＧｄＢａ２Ｃｕ３Ｏ７−δ（酸化物超電導層）を形成した。次いで酸化物超電導層上にスパッタ法により２μｍ厚のＡｇからなる保護層を形成した。次いで、この試料に対して酸素雰囲気大気圧化で５００℃、１０時間の酸素アニールを行い、２６時間の炉冷却後に取り出した。次いで、基材の裏面側にスパッタ法により１μｍ厚のＡｇを積層した。
以上の工程を経て、酸化物超電導線材を作製した。 EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited to these Examples.
<Preparation of sample>
First, the surface of a tape-shaped substrate made of Hastelloy C-276 (trade name of Haynes, USA) having a width of 10 mm and a thickness of 0.1 mm was polished using alumina having an average particle diameter of 3 μm. Next, the surface of the substrate was degreased and washed with acetone.
Al 2 O 3 (diffusion prevention layer; film thickness 100 nm) is formed on the main surface of the base material by sputtering, and Y 2 O 3 (bed layer; film thickness 30 nm) is formed thereon by ion beam sputtering. Was deposited.
Next, MgO (IBAD layer; film thickness: 5 to 10 nm) is formed on the bed layer by ion beam assisted vapor deposition (IBAD method), and then CeO 2 having a thickness of 500 nm by pulse laser vapor deposition (PLD method). (Cap layer) was formed. Next, a 2.0 μm thick GdBa 2 Cu 3 O 7-δ (oxide superconducting layer) was formed on the CeO 2 layer by the PLD method. Next, a protective layer made of Ag having a thickness of 2 μm was formed on the oxide superconducting layer by sputtering. Subsequently, this sample was subjected to oxygen annealing at 500 ° C. for 10 hours under an atmospheric pressure of oxygen atmosphere, and the sample was taken out after 26 hours of furnace cooling. Next, Ag having a thickness of 1 μm was laminated on the back side of the substrate by sputtering.
Through the above steps, an oxide superconducting wire was produced.

上述の酸化物超電導線材を３本用意した。それぞれの酸化物超電導線材の長さは、２５ｃｍとした。これらのうち、１本の酸化物超電導線材に関しては両端部からそれぞれ５ｃｍを、残る２本の酸化物超電導線材は、一端から５ｃｍをエッチングして、保護層を除去し、酸化物超電導層を露出させた。エッチングには、アンモニア・過酸化水素混合溶液を用いた。   Three oxide superconducting wires described above were prepared. The length of each oxide superconducting wire was 25 cm. Of these, one oxide superconducting wire is etched 5 cm from both ends, and the remaining two oxide superconducting wires are etched 5 cm from one end to remove the protective layer and expose the oxide superconducting layer. I let you. For the etching, a mixed solution of ammonia and hydrogen peroxide was used.

次に、上述の酸化物超電導層の成膜に用いたターゲットを粉砕して、平均粒径サイズ５μｍのＧｄＢａ２Ｃｕ３Ｏ７−δ（以下、ＧｄＢＣＯ）の粒状体（粉末）を採取した。バインダとしてＰＶＢを用いて、これをエタノールに溶かした溶液１０ｍｌに対して、採取した粒状体を５ｇ添加して、粒状体を含むペーストを作製した。 Next, the target used for forming the oxide superconducting layer was pulverized to collect GdBa 2 Cu 3 O 7-δ (hereinafter referred to as GdBCO) granules (powder) having an average particle size of 5 μm. Using PVB as a binder, 5 g of the collected granule was added to 10 ml of a solution obtained by dissolving this in ethanol to prepare a paste containing the granule.

次に、一端の保護層をエッチングした一対の酸化物超電導線材の露出する酸化物超電導層にペーストを塗布した。さらに、残る酸化物超電導線材を橋渡しするように重ね合わせて、図２に示すように各線材を配置した。
次に、線材と同幅（１０ｍｍ）の溝を設けたアルミナ製のブロックを用意し、溝内に重ね合わせた酸化物超電導線材を収納した。さらに、別途用意した溝幅より若干小さい幅のアルミナ製のブロックで、溝内の酸化物超電導線材の上方に配置し、２．５Ｎ／ｃｍ２の負荷を加えた。負荷を加えた状態で、５００℃、２４時間、大気中の環境で加熱して、脱脂を行い、さらに９５０℃、１６時間、大気中の環境で加熱した。これにより、線材間に挟み込まれた粒状体の焼結がなされて、酸化物超電導体からなる接合層を形成した。 Next, the paste was applied to the exposed oxide superconducting layer of the pair of oxide superconducting wires obtained by etching the protective layer at one end. Further, the remaining oxide superconducting wires were overlapped so as to be bridged, and the respective wires were arranged as shown in FIG.
Next, an alumina block provided with a groove having the same width (10 mm) as the wire was prepared, and the superconducting oxide superconducting wire superimposed in the groove was accommodated. Further, an alumina block having a width slightly smaller than the groove width prepared separately was disposed above the oxide superconducting wire in the groove, and a load of 2.5 N / cm 2 was applied. In a state where a load was applied, heating was performed in an air environment at 500 ° C. for 24 hours, degreasing was performed, and heating was further performed in an air environment at 950 ° C. for 16 hours. Thereby, the granular material sandwiched between the wire rods was sintered to form a bonding layer made of an oxide superconductor.

次に、酸素雰囲気大気圧化で５００℃、１０時間の酸素アニールを行い、２６時間の炉冷却後に取り出した。これにより、再度、酸化物超電導層に酸素を供給した。   Next, oxygen annealing was performed at 500 ° C. for 10 hours under atmospheric pressure, and the furnace was taken out after cooling for 26 hours. Thereby, oxygen was again supplied to the oxide superconducting layer.

次いで、２０μｍ厚のＳｎメッキ（半田）が両面に施されたＣｕ製の金属テープの位置面上に接続された３本の酸化物超電導線を配置した。さらに、２９０℃に加熱されたロールを通過させて、酸化物超電導線の外周を包み込むように金属テープを略Ｃ字形に折り曲げた。これにより、接続された３本の酸化物超電導線の外周を金属テープで覆い、接続部を補強した。
以上の工程を経て、図２に示す酸化物超電導線材の接続構造体を作製した。 Subsequently, three oxide superconducting wires connected on the position surface of a Cu metal tape having Sn plating (solder) with a thickness of 20 μm applied on both surfaces were arranged. Further, the metal tape was bent into a substantially C shape so as to wrap around the outer periphery of the oxide superconducting wire through a roll heated to 290 ° C. Thereby, the outer periphery of the three connected oxide superconducting wires was covered with the metal tape, and the connecting portion was reinforced.
Through the above steps, the oxide superconducting wire connection structure shown in FIG. 2 was produced.

＜評価＞
（臨界電流値Ｉｃ）
上述の接続構造体の接続部において、各線材の酸化物超電導層の間で、超電導特性を持たせた接続ができているかを確認するために、接続部を挟んでＩｃ測定を行った。図４に示すように、接続構造体３１に対し、電源２１、電流計２２、電圧計２３を接続した。電圧計２３の端子間距離は３０ｃｍとした。液体窒素により冷却しながら臨界電流値Ｉｃを測定したところ、臨界電流値Ｉｃは、２６Ａであった。この結果から、接続部において、超電導特性を持たせた接続の実現が確認された。 <Evaluation>
(Critical current value Ic)
In the connection part of the connection structure described above, Ic measurement was performed with the connection part interposed between the oxide superconducting layers of the respective wires to confirm whether or not a connection with superconducting characteristics was made. As shown in FIG. 4, a power source 21, an ammeter 22, and a voltmeter 23 were connected to the connection structure 31. The distance between terminals of the voltmeter 23 was 30 cm. When the critical current value Ic was measured while cooling with liquid nitrogen, the critical current value Ic was 26A. From this result, it was confirmed that a connection having superconducting characteristics was realized in the connection portion.

（機械特性（最小曲げ半径））
次に、金属テープにより補強することによる、機械特性の向上について評価した。
上述の工程で作製した金属テープにより補強したサンプルを２つ用意した（サンプルＮｏ．３、Ｎｏ．４）。また、上述の工程のうち、金属テープで覆い補強する工程を行わなかったサンプルを２つ用意した（サンプルＮｏ．１、Ｎｏ．２）。
これらサンプルに対して、曲げ試験を行った。曲げ試験は、所定の曲率半径を有する曲げ治具に、サンプルを沿わせて曲げて引張応力を印加することで行う。また、曲げ試験前後の臨界電流値Ｉｃを測定し、試験後の臨界電流値Ｉｃが試験前の臨界電流値Ｉｃに対して、９５％以上となる限界の曲げ半径（最小曲げ半径）を測定した。測定結果を表１に示す。 (Mechanical properties (minimum bending radius))
Next, the improvement of mechanical properties by reinforcing with metal tape was evaluated.
Two samples reinforced with the metal tape produced in the above-described process were prepared (Sample No. 3, No. 4). Moreover, the sample which did not perform the process of covering and reinforcing with a metal tape among the above-mentioned processes was prepared (sample No. 1, No. 2).
A bending test was performed on these samples. The bending test is performed by bending a sample along a bending jig having a predetermined radius of curvature and applying a tensile stress. Also, the critical current value Ic before and after the bending test was measured, and the critical bending radius (minimum bending radius) at which the critical current value Ic after the test was 95% or more of the critical current value Ic before the test was measured. . The measurement results are shown in Table 1.

Figure 0006178779
Figure 0006178779

表１に示すように、金属テープによる補強を行ったサンプルは、最小曲げ半径が比較的小さく、このような補強が効果的であることが確認された。
また、金属テープによる補強を行っていないサンプルも、半径２５ｍｍ以上の範囲であれば、曲げに対して劣化を抑えうることが確認された。 As shown in Table 1, the sample that was reinforced with the metal tape had a relatively small minimum bend radius, and it was confirmed that such reinforcement was effective.
It was also confirmed that the sample not reinforced with the metal tape can suppress deterioration against bending if the radius is within a range of 25 mm or more.

１、１Ａ、２００…酸化物超電導線材（超電導線材）、１ａ…端部、５…接続部、１０…基材、１１…中間層、１２、２０１…酸化物超電導層（超電導層）、１３…保護層、１４…接合層、１５…金属テープ、１６…半田、３０、３１…接続構造体（超電導線材の接続構造体）、２０２…シース材 DESCRIPTION OF SYMBOLS 1, 1A, 200 ... Oxide superconducting wire (superconducting wire), 1a ... End part, 5 ... Connection part, 10 ... Base material, 11 ... Intermediate layer, 12, 201 ... Oxide superconducting layer (superconducting layer), 13 ... Protective layer, 14 ... bonding layer, 15 ... metal tape, 16 ... solder, 30, 31 ... connection structure (connection structure of superconducting wire), 202 ... sheath material

Claims (4)

耐熱性の金属からなる基材と、前記基材の一方の面側に位置する超電導層と、前記超電導層の一方の面に位置するＡｇ又はＡｇ合金からなる保護層と、を有し、前記超電導層の少なくとも一部が前記保護層から露出した状態で厚さ方向に互いに対向して配置されたテープ状の一対の超電導線材と、
厚さ方向に対向して配置された前記超電導層同士を接合する接合層と、を備え、
前記接合層が、粒状体が焼結されてなる多孔質の超電導体であり、
前記接合層が、前記保護層と接触して隣接し、
前記超電導層の厚さが、０．５μｍ以上５μｍ以下である、超電導線材の接続構造体。 Has a substrate made of a refractory metal, and the superconducting layer located on one surface side of the substrate, and a protective layer made of Ag or Ag alloy is located on the surface of the hand of the superconducting layer, A pair of tape-shaped superconducting wires disposed opposite to each other in the thickness direction with at least a part of the superconducting layer exposed from the protective layer;
A bonding layer for bonding the superconducting layers arranged facing each other in the thickness direction,
The bonding layer is a porous superconductor formed by sintering a granular material,
The bonding layer is adjacent to and in contact with the protective layer ;
A connection structure for a superconducting wire , wherein the thickness of the superconducting layer is 0.5 μm or more and 5 μm or less . 前記接合層が設けられた接続部を含む超電導線材の外周が金属テープにより覆われている、請求項１に記載の超電導線材の接続構造体。 The superconducting wire connection structure according to claim 1, wherein an outer periphery of the superconducting wire including the connection portion provided with the bonding layer is covered with a metal tape. 前記超電導層と前記接合層との組成が同じである請求項１又は２に記載の超電導線材の接続構造体。 The superconducting wire connecting structure according to claim 1 or 2 , wherein the superconducting layer and the bonding layer have the same composition. 耐熱性の金属からなる基材と、前記基材の一方の面側に位置する超電導層と、前記超電導層の一方の面に位置するＡｇ又はＡｇ合金からなる保護層と、を有する一対の超電導線材を用意し、
一対の前記超電導線材の前記保護層の一部をエッチングにより除去し、前記超電導層を露出させ、
一対の前記超電導線材の前記超電導層の前記保護層から露出した部分を厚さ方向に対向させ、前記超電導層同士の間にバインダと混合した状態で超電導体の粒状体を塗布するとともに一対の前記超電導線材を重ね合わせ、
一対の前記超電導線材を介して前記粒状体に２．５Ｎ／ｃｍ２ の負荷を加えた状態で、５００℃、２４時間で脱脂し、さらに９５０℃、１６時間で加熱することで前記粒状体を焼結し、超電導体からなる多孔質の接合層を形成する、超電導線材の接続構造体の製造方法。 A substrate made of a heat-resistant metal, and the superconducting layer located on one surface side of the substrate, the pair having a protective layer made of Ag or Ag alloy is located on the surface of the hand of the superconducting layer Prepare superconducting wire,
A part of the protective layer of the pair of superconducting wires is removed by etching, the superconducting layer is exposed,
The portions exposed from the protective layer of the superconducting layer of the pair of superconducting wires are opposed to each other in the thickness direction, and a superconductor granular material is applied while being mixed with a binder between the superconducting layers. Superconducting wire
In a state where a load of 2.5 N / cm 2 is applied to the granular body through a pair of superconducting wires, the granular body is degreased at 500 ° C. for 24 hours and further heated at 950 ° C. for 16 hours. A method for producing a superconducting wire connecting structure, comprising sintering and forming a porous bonding layer made of a superconductor.
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