JP3701349B2

JP3701349B2 - Superconducting wire manufacturing method and superconducting wire

Info

Publication number: JP3701349B2
Application number: JP23309595A
Authority: JP
Inventors: 庄治岩崎; 謙次後藤; 伸行定方; 隆斉藤; 宰河野
Original assignee: Fujikura Ltd
Current assignee: Fujikura Ltd
Priority date: 1995-09-11
Filing date: 1995-09-11
Publication date: 2005-09-28
Anticipated expiration: 2015-09-11
Also published as: JPH0982152A

Description

【０００１】
【発明の属する技術分野】
本発明は、医療用ＭＲＩ用マグネット、核融合炉用トロイダルマグネット、粒子加速機用マグネット、超電導発電機用マグネット、磁気浮上列車用マグネット等に利用される高強度の超電導線及びその製造方法に関する。
【０００２】
【従来の技術】
一般に、超電導線は、超電導体からなる芯部の外周に安定化材などからなる付属部を設けた構造となっている。このような超電導線の一種に内部補強安定化型Ｎｂ₃Ｓｎ系超電導線が知られている。
図４は、内部補強安定化型Ｎｂ₃Ｓｎ系超電導線の例を示すものである。この内部補強安定化型Ｎｂ₃Ｓｎ系超電導線１は、Ｃｕ−Ｓｎ合金からなる基地の内部に無数の極細のＮｂ₃Ｓｎ超電導フィラメントが配列されてなる芯部２の外周に、ＴａあるいはＮｂからなる拡散防止層３を介してＣｕ−Ｎｂ合金からなる補強層４が設けられ、さらにこの外周にＣｕなどからなる安定化層５が設けられたものである。
このような構造の内部補強安定化型Ｎｂ₃Ｓｎ系超電導線１は、補強層を有してない構造の超電導線と比べて外部からの補強が必要がないため、コンパクトな超電導マグネットの作製に好適に用いられていた。
【０００３】
次に、このような内部補強安定化型Ｎｂ₃Ｓｎ系超電導線１の一般的な製造方法を図５を用いて説明する。
まず、図５（Ａ）に示すようなＮｂからなるロッド状の芯材１０の外周にＣｕ−Ｓｎ合金からなる管体１１を被せ、全体を縮径して図５（Ｂ）に示すような複合体１４を得る。次いで、図５（Ｃ）に示すように前記複合体１４を複数本集合してＣｕ−Ｓｎ合金の管体１５に挿入し、さらに縮径し、図５（Ｄ）に示す一次素線１６を得る。次いで、この一次素線１６を図５（Ｅ）に示すように複数本集合してＣｕ−Ｓｎ合金からなる管体１７に挿入し、更に縮径して図５（Ｆ）に示すような二次素線１８を作製する。
【０００４】
次いで、前記二次素線１８を複数本集合して、図５（Ｇ）に示すようにＣｕのパイプ２０に挿入した後、このパイプ２０の外方に拡散防止層３となるべきＴａあるいはＮｂからなる拡散防止管２２を被せ、ついで該拡散防止管２２の外周に補強層４となるべきＣｕ−Ｎｂ合金からなる補強管２３を被せ、ついで該補強管２３の外周に安定化層５となるべきＣｕなどからなる被覆管２４を被せ、さらに全体を最終的に得るべき直径まで縮径した後、拡散熱処理を行うことにより、二次素線１８の内部のＮｂの極細フィラメントとＳｎを反応させてＮｂ₃Ｓｎ超電導フィラメントを生成させて、図４に示すような内部補強安定化型Ｎｂ₃Ｓｎ系超電導線１を製造していた。
【０００５】
【発明が解決しようとする課題】
しかしながら従来の超電導線の製造方法においては、縮径加工を施して伸線する際、異種金属間の整合が難しく、特に、補強層４を形成する材料としてＣｕ−Ｎｂ合金を用いる場合、このＣｕ−Ｎｂ合金と、拡散防止層３を形成する材料であるＴａあるいはＮｂとの整合が困難で、伸線するにつれて拡散防止層３にクラック等の欠陥が生じたり、断線が起り易くなるため、伸線できる長さが短かく、得られる超電導線の長さも数十ｍ程度と短く、製造効率が悪かった。
【０００６】
本発明は、上記事情に鑑みてなされたもので、縮径加工が容易で、得られる超電導線の長さを大幅に長くすることができる超電導線の製造方法と、これによって得られる線長さが大幅に長い超電導線を提供することにある。
【０００７】
【課題を解決するための手段】
請求項１記載の発明にあっては、合金系超電導体からなる芯部または熱処理によって超電導体となる材料を具備する芯部の外周にＴａあるいはＮｂからなる拡散防止層を設け、さらにこの外周にＣｕ−Ｎｂ合金からなる補強層を設ける超電導線の製造方法において、芯部の外周にＴａあるいはＮｂからなる拡散防止層を形成した後、該拡散防止層の外周にＣｕからなるクッション材を被せ、さらに該クッション材の外周にＣｕ−Ｎｂ合金からなる補強材を被せた後、縮径加工を施す工程を具備する超電導線の製造方法を前記課題の解決手段とした。
また、請求項２記載の発明にあっては、請求項１記載の超電導線の製造方法において、クッション材の厚みを、超電導線線径の１．５％以上とすることを前記課題の解決手段とした。
【０００８】
また、請求項３記載の発明にあっては、合金系超電導体からなる芯部または熱処理によって超電導体となる材料を具備する芯部の外周にＴａあるいはＮｂからなる拡散防止層が設けられ、さらにこの外周にＣｕ−Ｎｂ合金からなる補強層が設けられてなる超電導線において、拡散防止層と補強層との間にＣｕからなるクッション層を介在させた超電導線を前記課題の解決手段とした。
【０００９】
本願発明者は、得られる超電導線の長さを大幅に長くすることができる超電導線の製造方法を提供するべく、特に、ＣｕとＣｕ−Ｎｂ合金との整合は良好であり、一方ＴａとＣｕとの整合は良好であることに着目し、隣合う異種金属層間の整合について種々の検討及び実験を重ねた結果、Ｔａからなる拡散防止管と、Ｃｕ−Ｎｂ合金からなる補強管との間にＣｕからなるクッション材を介在させることにより、隣合う金属層間の整合が良好となり、伸線できる長さを大幅に向上させることができることを究明し、本発明を完成したのである。
【００１０】
【発明の実施の形態】
図１から図２は、内部補強安定化型Ｎｂ₃Ｓｎ系超電導線の製造方法に本発明を適用した例を示すもので、超電導線を製造するには、まず、図１（Ａ）に示すようにＮｂロッドからなる芯材３０にＣｕ−Ｓｎ合金からなる管体３１を被せた後、スウェージング加工、引抜加工などの縮径加工によって所望の直径まで縮径して図１（Ｂ）に示す複合体３４を作製する。前記芯材３０としては、ＮｂまたはＮｂをＴｉに添加してなるものを用いるのが望ましく、Ｔｉが添加されていると無添加の場合と比べて高磁界における臨界電流特性が向上する。なお、管体３１は図面に示すような単管状のものに限るものではなく、柱状体に複数の透孔が形成された形状のものなどを用い、複数の透孔の各々に芯材３０を挿入して複合材を形成することもできる。
【００１１】
次いで、前記複合体３４を複数本集合してＣｕ−Ｓｎ合金の管体３５に図１（Ｃ）に示すように収納して縮径し、図１（Ｄ）に示す一次素線３６を作製し、次いで、この一次素線３６を図１（Ｅ）に示すように複数本集合してＣｕ−Ｓｎ合金からなる管体３７に挿入し、更に縮径加工を施して図１（Ｆ）に示すような二次素線３８を作製する。この二次素線３８の内部構造は、Ｃｕ−Ｓｎ合金からなる基地の内部にＮｂからなる極細のフィラメントが多数分散された構造となっている。なお、前記二次素線３８を更に複数本集合してＣｕ−Ｓｎ合金管に挿入し、縮径する処理を必要に応じて複数回行って複合体を作製しても良い。なお、前記二次素線３８形成用として用いたＣｕ−Ｓｎ合金のＳｎ濃度が低い場合には、その外周にＳｎのメッキ層を形成して以下の工程に用いても良い。
【００１２】
次いで、図１（Ｇ）に示すように前記二次素線３８の外周に拡散防止層となるべきＴａあるいはＮｂからなる拡散防止管４２を被せ、続いて図２に示すようにこの拡散防止管４２の外周にクッション材からなる管体４３を被せ、続いて該管体４３の外周に補強材からなる補強管４４を被せ、さらに該補強管４４の外周に安定化材からなる被覆管４５を被せ、更に全体を最終的に得るべき直径まで縮径加工により伸線し、素線を形成する。なお、この例では、１本の二次素線３８の外周に拡散防止管４２を被せた後、さらにクッション材からなる管体４３を被せているが、二次素線３８を複数本集合してＣｕパイプに挿入した後、このＣｕパイプの外周に拡散防止管４２を被せ、さらに拡散防止管４２の外周にクッション材からなる管体４３を被せるようにしても良い。
【００１３】
前記管体４３をなすクッション材としては、Ｃｕが挙げられる。
前記管体４３の厚みは、目的とする超電導線線径によって異るが、１０μｍ以上が好ましく、より好ましくは１５μｍ以上〜２０μｍ以下とされる。管体４３の厚みが１０μｍ未満であると薄過ぎて前記管体４３自身にクラックが生じたり、あるいは拡散防止管４２までクラックが生じてしまう恐れがあり、伸線できる長さを大幅に向上させることができない。また、２０μｍを超えて厚くしてももはや効果の増大は期待できず、目的とする超電導線内のＣｕの割合が多くなりすぎて超電導部分の割合が少なくなる。
前記補強管４４をなす補強材としては、Ｃｕ−Ｎｂ合金が挙げられる。補強管４４としてＣｕ−Ｎｂ合金を用いた場合、補強管４４はＣｕの金属マトリックスの内部にＮｂフィラメントが多数分散配列された構造を有している。この補強管４４は、ＣｕとＮｂの両元素が互いにほとんど固溶しないという性質を有することを利用して製造されたもので、Ｃｕ−Ｎｂ合金をその溶湯から鋳造した際に、Ｃｕマトリックス中にＮｂ樹枝状晶が生成された鋳塊を得ることができ、この鋳塊を冷間線引加工することでＮｂ樹枝状晶を引き延ばしてフィラメント状に加工することができ、これによりＣｕのマトリックスの内部にＮｂフィラメントが分散配列された構造が得られる。このＮｂフィラメントは、Ｃｕのマトリックス中に分散配列されるが、このＮｂフィラメントがＣｕのマトリックスを強化するので、補強管４４はＣｕからなるものより耐力が向上する。更に、ＮｂはＣｕにほとんど固溶しないので、補強管４４の導電率が低下することもなく、補強管４４の導電率は充分に高いものとなる。
また、前記被覆管４５をなす安定化材としては、Ｃｕ、Ａｌなどの金属材料が挙げられる。
【００１４】
ここで縮径加工を施して伸線するとき、ＴａあるいはＮｂからなるからなる拡散防止管４２と、Ｃｕ−Ｎｂ合金からなる補強管４４との間にＣｕからなる管体４３を介在させると、隣合う金属層間の整合が良好となるので、従来のようにＴａあるいはＮｂからなる拡散防止管の外周にＣｕ−Ｎｂ合金からなる補強管を被せた状態で伸線する場合と比べて、拡散防止層となる拡散防止管４２や補強層となる補強管４４にクラックが生じることや断線が起こることが低減されるので、縮径加工が容易となり、伸線できる長さを大幅に向上させることができ、線長さが大幅に長い素線が得られる。
【００１５】
次いで、前記素線を５００〜６５０℃で数十時間〜数百時間加熱する拡散熱処理を行うことにより、図３に示すような内部補強安定型Ｎｂ₃Ｓｎ系超電導線５１を製造することができる。
前述のような拡散熱処理を行うと、Ｃｕ−Ｓｎ合金からなる基地の内部に極細のＮｂ₃Ｓｎ超電導フィラメントが配列された構造のＮｂ₃Ｓｎ超電導体が得られる。
【００１６】
前述のように製造された内部補強安定化型Ｎｂ₃Ｓｎ系超電導線５１は、Ｃｕ−Ｓｎ合金からなる基地の内部に無数のＮｂ₃Ｓｎ超電導フィラメントが配列されてなる芯部５２と、これの外周に設けられた拡散防止層５３と、該拡散防止層５３の外周に設けられたＣｕからなるクッション層５４と、該クッション層５４の外周に設けられた補強層５５と、さらにこの補強層５５の外周に設けられた安定化層５６とから構成されている。
前記Ｃｕからなるクッション層５４の厚みは、１５〜１７μｍ程度である。
【００１７】
この例の内部補強安定化型Ｎｂ₃Ｓｎ系超電導線の製造方法にあっては、芯部５２の外周にＴａあるいはＮｂからなる拡散防止管４２を被せた後、該拡散防止層４２の外周にＣｕからなる管体４３を被せ、ついでこの管体４３の外周にＣｕ−Ｎｂ合金からなる補強管４４を被せ、さらにこの外周にＣｕなどからなる被覆管４５を被せた後、縮径加工を施す工程を具備することより、縮径加工を施して伸線するとき、隣合う金属層間の整合が良好となるので、従来のようにＴａあるいはＮｂからなる拡散防止管の外周にＣｕ−Ｎｂ合金からなる補強管を被せた状態で伸線する場合と比べて、拡散防止管４２にクラックが生じることや断線が起こることが低減されるので、縮径加工が容易となり、伸線できる長さを大幅に向上させることができ、従って線長が大幅に長い内部補強安定化型Ｎｂ₃Ｓｎ系超電導線５１が得られ、製造効率が向上する。
【００１８】
このようにして得られた内部補強安定化型Ｎｂ₃Ｓｎ系超電導線５１は、拡散防止層５３と補強層５５との間にＣｕからなるクッション層５４を介在させたものであるので、従来の内部補強安定化型Ｎｂ₃Ｓｎ系超電導線より線長が大幅に長いものであっても、隣合う金属層間の整合が良好であり、拡散防止層５３にクラック等の不良が生じていないため、機械的強度が優れるうえ、前記クラック等に起因してＳｎが補強層５５および最外層の安定化層５６まで拡散するのを防止できるので、Ｓｎの拡散による安定化層５６の汚染が防止できる。
【００１９】
なお、前記の例においては、Ｎｂ_３Ｓｎ系超電導線の製造方法に本発明の超電導線の製造方法を適用した例について説明したが、本発明の製造方法をＮｂ₃Ｓｎの他、Ｎｂ_３Ｇａ、Ｎｂ_３Ｇｅ、Ｎｂ_３Ａｌ、Ｖ_３Ｇａ、Ｎｂ−Ｔｉなどの超電導線の製造方法に適用してもよいのは勿論である。
【００２０】
【実施例】
以下、本発明を、実施例および比較例により、具体的に説明するが、本発明はこれらの実施例のみに限定されるものではない。
（実施例１）
直径１４ｍｍのＮｂ−１．２ｗｔ％ＴｉロッドをＣｕ−１３ｗｔ％Ｓｎ合金からなる外径２５ｍｍ、内径１５ｍｍの管体に挿入し、縮径して直径１．０ｍｍの複合体を得た。次にこの複合体を９１本集合し、Ｃｕ−８ｗｔ％Ｓｎ合金からなる外径１１．５ｍｍ、内径１０．５ｍｍの管体に挿入し、縮径加工を行って直径１．１４ｍｍの一次素線を得た。次いで、この一次素線を９１本集合し、Ｃｕ−８ｗｔ％Ｓｎ合金からなる外径１３ｍｍ、内径１２ｍｍの管体に挿入し、縮径加工を行って直径１１ｍｍの二次素線を作製した。
【００２１】
次いで、このようにして得られた二次素線の外周に、外径１３ｍｍ、内径１２ｍｍのＴａからなる拡散防止管を被せ、ついでこの拡散防止管の外周に外径１４ｍｍ、内径１３．２ｍｍのＣｕからなる管体を被せた後、この管体の外周に外径１８ｍｍ、内径１４．５ｍｍのＣｕ−２０ｗｔ％Ｎｂからなる補強管を被せ、さらにこの補強管の外周に外径１８．５ｍｍ、内径１７．５ｍｍのＣｕからなる被覆管を被せた後、全体を径１．０ｍｍまで縮径した後、６７５℃で１０日間加熱する拡散熱処理を行うことにより、線長１ｋｍのＣｕ−Ｎｂ／（Ｎｂ，Ｔｉ）₃Ｓｎ超電導線を得た。このようにして得られた超電導線の芯部は、Ｃｕ−Ｓｎ合金からなる基地の内部に径３．９μｍの（Ｎｂ，Ｔｉ）₃Ｓｎ超電導フィラメントが８，２８１本配列された構造であった。
【００２２】
（実施例２）
直径７．６ｍｍのＮｂロッドをＣｕ−６ｗｔ％Ｓｎ合金からなる外径１８ｍｍ、内径８ｍｍの管体に挿入し、縮径して直径１．０ｍｍの複合体を得た。次にこの複合体を９１本集合し、Ｃｕ−６ｗｔ％Ｓｎ合金からなる外径１１．５ｍｍ、内径１０．５ｍｍの管体に挿入し、縮径加工を行って直径１．０ｍｍの一次素線を得た。次いで、この一次素線を９１本集合し、Ｃｕ−６ｗｔ％Ｓｎ合金からなる外径１１．５ｍｍ、内径１０．５ｍｍの管体に挿入し、縮径加工を行って直径９．０ｍｍの二次素線を作製した。
【００２３】
次いで、この二次素線の外周に外径９．９ｍｍ、内径９．３ｍｍのＴａからなる拡散防止管を被せ、ついでこの拡散防止管の外周に外径１１．２ｍｍ、内径１０．２ｍｍのＣｕからなる管体を被せた後、この管体の外周に外径１４ｍｍ、内径１２ｍｍのＣｕ−１５ｗｔ％Ｎｂからなる補強管を被せた後、さらにこの補強管の外周に外径１５．４ｍｍ、内径１４．６ｍｍのＣｕからなる被覆管を被せた後、全体を径０．４６ｍｍまで縮径したのち、前記実施例１と同様にして拡散熱処理を行うことにより、線長１ｋｍのＣｕ−Ｎｂ／Ｎｂ₃Ｓｎ超電導線を得た。ここで得られた超電導線の芯部は、Ｃｕ−Ｓｎ合金からなる基地の内部に径１．８μｍのＮｂ₃Ｓｎ超電導フィラメントが８，２８１本配列された構造であった。
【００２４】
（比較例１）
前記実施例１と同様にして二次素線を作製した。次いで、作製した二次素線の外周に外径１３ｍｍ、内径１２ｍｍのＴａからなる拡散防止管を被せ、ついでこの拡散防止管の外周に外径１７ｍｍ、内径１３．５ｍｍのＣｕ−２０ｗｔ％Ｎｂからなる補強管を被せ、さらにこの補強管の外周に外径１８．５ｍｍ、内径１７．５ｍｍのＣｕからなる被覆管を被せた後、全体を径１．０ｍｍまで縮径した後、前記実施例１と同様にして拡散熱処理を行うことにより、線長５０ｍのＣｕ−Ｎｂ／（Ｎｂ，Ｔｉ）₃Ｓｎ系超電導線を得た。このようにして得られた超電導線の芯部は、Ｃｕ−Ｓｎ合金からなる基地の内部に径３．９μｍの（Ｎｂ，Ｔｉ）₃Ｓｎ超電導フィラメントが８，２８１本配列された構造のものであった。
【００２５】
（比較例２）
前記実施例２と同様にして二次素線を作製した。次いで、作製した二次素線の外周に外径９．９ｍｍ、内径９．３ｍｍのＴａからなる拡散防止管を被せ、ついでこの拡散防止管の外周に外径１４ｍｍ、内径１１．５ｍｍのＣｕ−１５ｗｔ％Ｎｂからなる補強管を被せ、さらにこの補強管の外周に外径１５．４ｍｍ、内径１４．６ｍｍのＣｕからなる被覆管を被せた後、全体を径０．４６ｍｍまで縮径した後、前記実施例１と同様にして拡散熱処理を行うことにより、線長４０ｍのＣｕ／（Ｎｂ，Ｔｉ）₃Ｓｎ超電導線を得た。このようにして得られた超電導線の芯部は、Ｃｕ−Ｓｎ合金からなる基地の内部に径１．８μｍのＮｂ₃Ｓｎ超電導フィラメントが８，２８１本配列された構造のものであった。
【００２６】
上記実施例１〜２で得られた超電導線と、比較例１〜２で得られた超電導線の線長を比較すると、実施例１〜２で得られた超電導線は、比較例１〜２の超電導線に比べて線長が大幅に長いことが分る。なお、比較例１〜２のものでは、これ以上の長さに伸線した場合に拡散防止層にクラック等の欠陥が生じた。
【００２７】
【発明の効果】
以上説明したように本発明の超電導線の製造方法にあっては、合金系超電導体からなる芯部または熱処理によって超電導体となる材料を具備する芯部の外周にＴａあるいはＮｂからなる拡散防止層を形成した後、該拡散防止層の外周にＣｕからなるクッション材を被せ、さらに該クッション材の外周にＣｕ−Ｎｂ合金からなる補強材を被せた後、縮径加工を施す工程を具備することにより、隣合う金属層間の整合が良好となり、従来のようにＴａあるいはＮｂからなる拡散防止管の外周にＣｕ−Ｎｂ合金からなる補強管を被せた状態で伸線する場合と比べて、拡散防止層にクラックが生じることや断線が起こることが低減されるので、縮径加工が容易となり、伸線できる長さを大幅に向上させることができ、従って線長が大幅に長い超電導線が得られ、製造効率が向上するという利点がある。
【００２８】
また、本発明の超電導線にあっては、拡散防止層と補強層との間にＣｕからなるクッション層を介在させたものであるので、従来の超電導線より線長が大幅に長いものであっても、隣合う金属層間の整合が良好であり、拡散防止層にクラック等が生じていないため、機械的強度が優れるうえ、前記クラック等に起因して補強層および安定化層までＳｎが拡散するのを防止できるのでＳｎの拡散による安定化層の汚染が防止できる。
【図面の簡単な説明】
【図１】（Ａ）〜（Ｇ）は、本発明の超電導線の製造方法の一例を工程順に示した断面図である。
【図２】本発明の超電導線の製造方法の一例を示した断面図である。
【図３】本発明の超電導線の一例を示す拡大断面図である。
【図４】従来の内部補強安定化型Ｎｂ₃Ｓｎ系超電導線の例を示す拡大断面図である。
【図５】（Ａ）〜（Ｇ）は、従来の内部補強安定化型Ｎｂ₃Ｓｎ系超電導線の製造方法を工程順に示した断面図である。
【符号の説明】
３０・・・芯材、３１・・・管体、３４・・・複合体、３５・・・管体、３６・・・一次素線、３７・・・管体、３８・・・二次素線、４２・・・拡散防止管、４３・・・管体、４４・・・補強管、５１・・・超電導線、５２・・・芯部、５３・・・拡散防止層、５４・・・クッション層、５５・・・補強層、５６・・・安定化層。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-strength superconducting wire used for medical MRI magnets, toroidal magnets for fusion reactors, magnets for particle accelerators, magnets for superconducting generators, magnets for magnetic levitation trains, and the like, and a method for manufacturing the same.
[0002]
[Prior art]
In general, a superconducting wire has a structure in which an attachment portion made of a stabilizing material or the like is provided on the outer periphery of a core portion made of a superconductor. As one type of such superconducting wires, an internally reinforced and stabilized Nb ₃ Sn-based superconducting wire is known.
FIG. 4 shows an example of an internally reinforced and stabilized Nb ₃ Sn-based superconducting wire. This internally-reinforced and stabilized Nb ₃ Sn-based superconducting wire 1 is formed from Ta or Nb on the outer periphery of a core portion 2 in which countless ultrafine Nb ₃ Sn superconducting filaments are arranged inside a base made of a Cu—Sn alloy. A reinforcing layer 4 made of a Cu—Nb alloy is provided through a diffusion preventing layer 3, and a stabilizing layer 5 made of Cu or the like is further provided on the outer periphery.
The internal reinforcing and stabilizing type Nb ₃ Sn based superconducting wire 1 having such a structure does not require external reinforcement as compared with a superconducting wire having no reinforcing layer, so that a compact superconducting magnet can be manufactured. It was used suitably.
[0003]
Next, a general manufacturing method of such an internally reinforced and stabilized Nb ₃ Sn-based superconducting wire 1 will be described with reference to FIG.
First, a tube 11 made of a Cu—Sn alloy is put on the outer periphery of a rod-shaped core material 10 made of Nb as shown in FIG. 5A, and the entire diameter is reduced, as shown in FIG. A composite 14 is obtained. Next, as shown in FIG. 5C, a plurality of the composites 14 are assembled and inserted into the Cu-Sn alloy tube 15, and the diameter is further reduced. The primary strand 16 shown in FIG. obtain. Next, as shown in FIG. 5 (E), a plurality of primary strands 16 are assembled and inserted into a tube body 17 made of a Cu—Sn alloy, and the diameter is further reduced, as shown in FIG. 5 (F). The next strand 18 is produced.
[0004]
Next, a plurality of the secondary strands 18 are assembled and inserted into a Cu pipe 20 as shown in FIG. 5G, and then Ta or Nb to be the diffusion prevention layer 3 is formed outside the pipe 20. Then, the diffusion prevention tube 22 is covered, and then the outer periphery of the diffusion prevention tube 22 is covered with a reinforcement tube 23 made of a Cu—Nb alloy to be the reinforcement layer 4, and then the outer periphery of the reinforcement tube 23 is the stabilization layer 5. After covering the cladding tube 24 made of power Cu and the like and further reducing the whole to the diameter to be finally obtained, diffusion heat treatment is performed to react Sn with the ultrafine Nb filament inside the secondary strand 18. Thus, an Nb ₃ Sn superconducting filament was generated to produce an internally reinforced and stabilized Nb ₃ Sn-based superconducting wire 1 as shown in FIG.
[0005]
[Problems to be solved by the invention]
However, in the conventional superconducting wire manufacturing method, it is difficult to match between different metals when wire drawing is performed by reducing the diameter. In particular, when using a Cu-Nb alloy as a material for forming the reinforcing layer 4, this Cu -It is difficult to match the Nb alloy with Ta or Nb which is a material for forming the diffusion prevention layer 3, and as the wire is drawn, defects such as cracks are likely to occur in the diffusion prevention layer 3, and disconnection is likely to occur. The length of the wire that can be drawn was short, and the length of the resulting superconducting wire was as short as several tens of meters, resulting in poor production efficiency.
[0006]
The present invention has been made in view of the above circumstances, and a method of manufacturing a superconducting wire that can be easily reduced in diameter and can greatly increase the length of the resulting superconducting wire, and the wire length obtained thereby. Is to provide a significantly longer superconducting wire.
[0007]
[Means for Solving the Problems]
In the invention according to claim 1, a diffusion prevention layer made of Ta or Nb is provided on the outer periphery of the core made of an alloy superconductor or the core made of a material that becomes a superconductor by heat treatment, and further on the outer periphery. In the method of manufacturing a superconducting wire in which a reinforcing layer made of a Cu-Nb alloy is provided, after forming a diffusion prevention layer made of Ta or Nb on the outer periphery of the core, a cushion material made of Cu is put on the outer periphery of the diffusion prevention layer, Furthermore, a superconducting wire manufacturing method comprising a step of reducing the diameter after covering the outer periphery of the cushion material with a reinforcing material made of a Cu—Nb alloy was used as means for solving the above problems.
In the invention according to claim 2, in the method for manufacturing a superconducting wire according to claim 1, the thickness of the cushion material is 1.5% or more of the superconducting wire diameter. It was.
[0008]
In the invention of claim 3, a diffusion prevention layer made of Ta or Nb is provided on the outer periphery of the core made of an alloy-based superconductor or the core made of a material that becomes a superconductor by heat treatment , In the superconducting wire in which a reinforcing layer made of a Cu—Nb alloy is provided on the outer periphery, a superconducting wire in which a cushion layer made of Cu is interposed between the diffusion preventing layer and the reinforcing layer was used as means for solving the above problems.
[0009]
In order to provide a method of manufacturing a superconducting wire that can significantly increase the length of the resulting superconducting wire, the inventor of the present application has particularly good matching between Cu and Cu-Nb alloy, while Ta and Cu As a result of various examinations and experiments on matching between adjacent dissimilar metal layers, a gap between the diffusion prevention tube made of Ta and the reinforcement tube made of the Cu-Nb alloy was noted. The present inventors completed the present invention by investigating that by interposing a cushion material made of Cu, the alignment between adjacent metal layers becomes good and the length that can be drawn can be greatly improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1 to 2 show an example in which the present invention is applied to a method of manufacturing an internally reinforced and stabilized Nb ₃ Sn-based superconducting wire. To manufacture a superconducting wire, first, as shown in FIG. As shown in FIG. 1B, the core body 30 made of an Nb rod is covered with a pipe body 31 made of a Cu—Sn alloy, and then the diameter is reduced to a desired diameter by a diameter reduction process such as a swaging process or a drawing process. The composite 34 shown is produced. As the core material 30, it is desirable to use Nb or a material obtained by adding Nb to Ti. When Ti is added, critical current characteristics in a high magnetic field are improved as compared with the case where Ti is not added. The tubular body 31 is not limited to a single tubular shape as shown in the drawings, and a tubular body having a shape in which a plurality of through holes are formed is used, and the core member 30 is provided in each of the plurality of through holes. It can also be inserted to form a composite material.
[0011]
Next, a plurality of the composites 34 are gathered and accommodated in a Cu-Sn alloy tube 35 as shown in FIG. 1 (C) and reduced in diameter to produce a primary strand 36 shown in FIG. 1 (D). Next, as shown in FIG. 1 (E), a plurality of the primary strands 36 are assembled and inserted into a tube body 37 made of a Cu—Sn alloy, and further subjected to a diameter reduction process, as shown in FIG. 1 (F). A secondary wire 38 as shown is produced. The internal structure of the secondary strand 38 is a structure in which a large number of ultrafine filaments made of Nb are dispersed inside a base made of a Cu—Sn alloy. Note that a plurality of the secondary strands 38 may be assembled and inserted into a Cu—Sn alloy tube, and the diameter may be reduced a plurality of times as necessary to produce a composite. When the Sn concentration of the Cu—Sn alloy used for forming the secondary strand 38 is low, a Sn plating layer may be formed on the outer periphery of the Cu—Sn alloy and used in the following steps.
[0012]
Next, as shown in FIG. 1 (G), the outer periphery of the secondary strand 38 is covered with a diffusion prevention pipe 42 made of Ta or Nb to be a diffusion prevention layer, and then this diffusion prevention pipe is shown in FIG. 42, the tube body 43 made of a cushioning material is covered on the outer periphery of the tube 42, the reinforcement tube 44 made of a reinforcing material is subsequently covered on the outer periphery of the tube body 43, and the cladding tube 45 made of a stabilizing material is further put on the outer periphery of the reinforcement tube 44. Then, the whole is further drawn to a diameter to be finally obtained by a reduction process to form a strand. In this example, after covering the outer periphery of one secondary strand 38 with a diffusion prevention tube 42 and further covering a tube body 43 made of a cushion material, a plurality of secondary strands 38 are assembled. After being inserted into the Cu pipe, the outer periphery of the Cu pipe may be covered with the diffusion prevention tube 42, and the outer periphery of the diffusion prevention tube 42 may be covered with a tube body 43 made of a cushion material.
[0013]
An example of the cushion material forming the tubular body 43 is Cu.
The thickness of the tube body 43 varies depending on the intended superconducting wire diameter, but is preferably 10 μm or more, more preferably 15 μm to 20 μm. If the thickness of the tube body 43 is less than 10 μm, the tube body 43 itself may be cracked or cracks may be generated up to the diffusion prevention tube 42, and the length that can be drawn is greatly improved. I can't. Further, even if the thickness exceeds 20 μm, the increase in the effect can no longer be expected, and the proportion of Cu in the target superconducting wire becomes too large and the proportion of the superconducting portion decreases.
An example of the reinforcing material forming the reinforcing tube 44 is a Cu—Nb alloy. When a Cu-Nb alloy is used as the reinforcing tube 44, the reinforcing tube 44 has a structure in which a large number of Nb filaments are dispersed and arranged inside a Cu metal matrix. This reinforcing tube 44 is manufactured by utilizing the property that both elements of Cu and Nb are hardly dissolved in each other. When a Cu—Nb alloy is cast from the molten metal, it is contained in the Cu matrix. An ingot in which Nb dendrites are formed can be obtained, and by cold drawing the ingot, the Nb dendrites can be stretched and processed into filaments, thereby forming a Cu matrix. A structure in which Nb filaments are dispersed and arranged inside is obtained. The Nb filaments are dispersed and arranged in the Cu matrix. However, since the Nb filaments reinforce the Cu matrix, the strength of the reinforcing tube 44 is improved compared to that made of Cu. Further, since Nb hardly dissolves in Cu, the conductivity of the reinforcing tube 44 does not decrease, and the conductivity of the reinforcing tube 44 is sufficiently high.
Examples of the stabilizing material forming the cladding tube 45 include metal materials such as Cu and Al.
[0014]
Here, when wire drawing is performed by reducing the diameter, if a tube 43 made of Cu is interposed between a diffusion prevention tube 42 made of Ta or Nb and a reinforcing tube 44 made of a Cu-Nb alloy, Compared to the case where the outer periphery of a diffusion prevention tube made of Ta or Nb is covered with a reinforcing tube made of a Cu—Nb alloy as in the conventional case, the alignment between adjacent metal layers is good, and diffusion prevention is thus achieved. Since the occurrence of cracks and disconnection in the diffusion prevention tube 42 serving as the layer and the reinforcement tube 44 serving as the reinforcement layer are reduced, the diameter reduction processing is facilitated, and the length that can be drawn can be greatly improved. Can be obtained, and a wire having a significantly long wire length can be obtained.
[0015]
Next, by performing a diffusion heat treatment in which the element wire is heated at 500 to 650 ° C. for several tens of hours to several hundred hours, an internally reinforced stable Nb ₃ Sn-based superconducting wire 51 as shown in FIG. 3 can be manufactured. .
Doing diffusion heat treatment as described above, Nb ₃ Sn superconductor Nb ₃ Sn superconducting filaments ultrafine inside of the base consisting of the Cu-Sn alloy are arranged structure.
[0016]
The internally-stabilized and stabilized Nb ₃ Sn-based superconducting wire 51 manufactured as described above includes a core portion 52 in which countless Nb ₃ Sn superconducting filaments are arranged inside a base made of a Cu—Sn alloy, A diffusion prevention layer 53 provided on the outer periphery, a cushion layer 54 made of Cu provided on the outer periphery of the diffusion prevention layer 53, a reinforcement layer 55 provided on the outer periphery of the cushion layer 54, and the reinforcement layer 55 And a stabilization layer 56 provided on the outer periphery of the substrate.
The thickness of the cushion layer 54 made of Cu is about 15 to 17 μm.
[0017]
In the method of manufacturing the internal reinforcing and stabilizing type Nb ₃ Sn-based superconducting wire of this example, after covering the outer periphery of the core portion 52 with the diffusion prevention pipe 42 made of Ta or Nb, the outer periphery of the diffusion prevention layer 42 is covered. After covering the tube body 43 made of Cu, and then covering the outer periphery of the tube body 43 with a reinforcing tube 44 made of a Cu—Nb alloy, and further covering the outer periphery with a cladding tube 45 made of Cu or the like, the diameter reduction processing is performed. By providing a process, when drawing is performed by reducing the diameter, matching between adjacent metal layers is improved, so that the outer periphery of the diffusion prevention tube made of Ta or Nb is conventionally formed from a Cu-Nb alloy. Compared to the case of drawing with the reinforcing tube covered, cracking and disconnection in the diffusion prevention pipe 42 are reduced, so that the diameter reduction process is facilitated and the length that can be drawn is greatly increased. Can be improved, Line length is significantly longer inner reinforcing-stabilized Nb ₃ Sn based superconducting wire 51 is obtained I, thereby improving the manufacturing efficiency.
[0018]
The thus obtained internal reinforcing and stabilizing Nb ₃ Sn superconducting wire 51 has a cushion layer 54 made of Cu interposed between the diffusion preventing layer 53 and the reinforcing layer 55, so that the conventional Even if the wire length is much longer than that of the internally reinforced and stabilized Nb ₃ Sn-based superconducting wire, the alignment between adjacent metal layers is good, and no defects such as cracks occur in the diffusion prevention layer 53. In addition to excellent mechanical strength, it is possible to prevent Sn from diffusing to the reinforcing layer 55 and the outermost stabilizing layer 56 due to the cracks and the like, so that contamination of the stabilizing layer 56 due to Sn diffusion can be prevented.
[0019]
In the above example, the example in which the superconducting wire manufacturing method of the present invention is applied to the manufacturing method of the Nb ₃ Sn-based superconducting wire has been described. However, the manufacturing method of the present invention is not limited to Nb ₃ Sn but Nb ₃ Ga. Of course, the present invention may be applied to a method of manufacturing a superconducting wire such as Nb ₃ Ge, Nb ₃ Al, V ₃ Ga, or Nb—Ti.
[0020]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited only to these Examples.
(Example 1)
An Nb-1.2 wt% Ti rod having a diameter of 14 mm was inserted into a tube having an outer diameter of 25 mm and an inner diameter of 15 mm made of a Cu-13 wt% Sn alloy, and reduced in diameter to obtain a composite having a diameter of 1.0 mm. Next, 91 composites were assembled, inserted into a tube body made of a Cu-8 wt% Sn alloy having an outer diameter of 11.5 mm and an inner diameter of 10.5 mm, and subjected to diameter reduction processing to produce a primary wire having a diameter of 1.14 mm. Got. Next, 91 pieces of the primary strands were assembled, inserted into a tube body made of a Cu-8 wt% Sn alloy having an outer diameter of 13 mm and an inner diameter of 12 mm, and reduced in diameter to produce a secondary strand having a diameter of 11 mm.
[0021]
Subsequently, the outer periphery of the secondary strand thus obtained is covered with a diffusion prevention tube made of Ta having an outer diameter of 13 mm and an inner diameter of 12 mm, and then the outer periphery of the diffusion prevention tube is outer diameter of 14 mm and inner diameter of 13.2 mm. After covering the tubular body made of Cu, the outer periphery of this tubular body was covered with a reinforcing tube made of Cu-20 wt% Nb having an outer diameter of 18 mm and an inner diameter of 14.5 mm, and further the outer diameter of this reinforcing tube was 18.5 mm. After covering with a cladding tube made of Cu having an inner diameter of 17.5 mm, the whole was reduced to a diameter of 1.0 mm, and then subjected to diffusion heat treatment that was heated at 675 ° C. for 10 days, whereby a Cu-Nb / ( Nb, Ti) ₃ Sn superconducting wire was obtained. The core part of the superconducting wire thus obtained had a structure in which 8,281 (Nb, Ti) ₃ Sn superconducting filaments having a diameter of 3.9 μm were arranged inside a base made of a Cu—Sn alloy. .
[0022]
(Example 2)
A Nb rod having a diameter of 7.6 mm was inserted into a tubular body having an outer diameter of 18 mm and an inner diameter of 8 mm made of a Cu-6 wt% Sn alloy, and reduced in diameter to obtain a composite having a diameter of 1.0 mm. Next, 91 composites were assembled and inserted into a tube body made of a Cu-6 wt% Sn alloy having an outer diameter of 11.5 mm and an inner diameter of 10.5 mm, and subjected to diameter reduction processing to produce a primary strand having a diameter of 1.0 mm. Got. Next, 91 of these primary strands are assembled and inserted into a tube body made of a Cu-6 wt% Sn alloy having an outer diameter of 11.5 mm and an inner diameter of 10.5 mm, and subjected to diameter reduction to obtain a secondary having a diameter of 9.0 mm. A strand was prepared.
[0023]
Next, a diffusion prevention tube made of Ta with an outer diameter of 9.9 mm and an inner diameter of 9.3 mm is put on the outer periphery of the secondary strand, and then the outer periphery of the diffusion prevention tube is placed with an outer diameter of 11.2 mm and an inner diameter of 10.2 mm. After covering the tube with a reinforcing tube made of Cu-15 wt% Nb with an outer diameter of 14 mm and an inner diameter of 12 mm, the outer periphery of the tube was further covered with an outer diameter of 15.4 mm and an inner diameter of After covering with a cladding tube made of Cu of 14.6 mm, the whole was reduced to a diameter of 0.46 mm, and then subjected to diffusion heat treatment in the same manner as in Example 1 to obtain a Cu-Nb / Nb having a wire length of 1 km. ₃ Sn superconducting wire was obtained. The core portion of the superconducting wire obtained here had a structure in which 8,281 Nb ₃ Sn superconducting filaments having a diameter of 1.8 μm were arranged inside a base made of a Cu—Sn alloy.
[0024]
(Comparative Example 1)
Secondary strands were produced in the same manner as in Example 1. Next, a diffusion prevention tube made of Ta having an outer diameter of 13 mm and an inner diameter of 12 mm is put on the outer periphery of the produced secondary strand, and then the outer periphery of the diffusion prevention tube is made of Cu-20 wt% Nb having an outer diameter of 17 mm and an inner diameter of 13.5 mm. After covering the outer periphery of the reinforcing tube with a cladding tube made of Cu having an outer diameter of 18.5 mm and an inner diameter of 17.5 mm, the whole was reduced to a diameter of 1.0 mm, and then Example 1 was applied. A Cu—Nb / (Nb, Ti) ₃ Sn superconducting wire having a wire length of 50 m was obtained by performing a diffusion heat treatment in the same manner as described above. The core of the superconducting wire thus obtained has a structure in which 8,281 (Nb, Ti) ₃ Sn superconducting filaments having a diameter of 3.9 μm are arranged inside a base made of a Cu—Sn alloy. there were.
[0025]
(Comparative Example 2)
Secondary strands were produced in the same manner as in Example 2. Next, a diffusion prevention tube made of Ta having an outer diameter of 9.9 mm and an inner diameter of 9.3 mm is put on the outer periphery of the produced secondary strand, and then the outer periphery of the diffusion prevention tube is made of Cu— with an outer diameter of 14 mm and an inner diameter of 11.5 mm. After covering the reinforcing tube made of 15 wt% Nb, and further covering the outer periphery of the reinforcing tube with a cladding tube made of Cu having an outer diameter of 15.4 mm and an inner diameter of 14.6 mm, the whole was reduced to a diameter of 0.46 mm, A diffusion heat treatment was performed in the same manner as in Example 1 to obtain a Cu / (Nb, Ti) ₃ Sn superconducting wire having a wire length of 40 m. The core part of the superconducting wire thus obtained had a structure in which 8,281 Nb ₃ Sn superconducting filaments having a diameter of 1.8 μm were arranged inside a base made of a Cu—Sn alloy.
[0026]
Comparing the superconducting wires obtained in Examples 1 and 2 above and the superconducting wires obtained in Comparative Examples 1 and 2, the superconducting wires obtained in Examples 1 and 2 were compared with Comparative Examples 1 and 2. It can be seen that the wire length is significantly longer than the superconducting wire. In Comparative Examples 1 and 2, defects such as cracks occurred in the diffusion prevention layer when the wire was drawn to a length longer than this.
[0027]
【The invention's effect】
As described above, in the method of manufacturing a superconducting wire of the present invention, a diffusion preventing layer made of Ta or Nb is formed on the outer periphery of the core made of an alloy superconductor or the core made of a material that becomes a superconductor by heat treatment. After the formation of the diffusion barrier layer, the outer periphery of the diffusion prevention layer is covered with a cushion material made of Cu, and further, the outer periphery of the cushion material is covered with a reinforcing material made of a Cu-Nb alloy, followed by a process of reducing the diameter. As a result, the alignment between adjacent metal layers is improved, and compared to the case where the outer periphery of a diffusion prevention tube made of Ta or Nb is covered with a reinforcing tube made of a Cu-Nb alloy as in the conventional case, diffusion prevention is achieved. Since the occurrence of cracks and breaks in the layer is reduced, the diameter can be easily reduced, and the length that can be drawn can be greatly improved. Therefore, a superconducting wire with a much longer wire length. The resulting, there is an advantage of improving the production efficiency.
[0028]
Further, in the superconducting wire of the present invention, a cushion layer made of Cu is interposed between the diffusion preventing layer and the reinforcing layer, so that the wire length is significantly longer than the conventional superconducting wire. However, since the matching between the adjacent metal layers is good and no crack or the like is generated in the diffusion preventing layer, the mechanical strength is excellent, and Sn is diffused to the reinforcing layer and the stabilization layer due to the crack and the like. Therefore, contamination of the stabilization layer due to Sn diffusion can be prevented.
[Brief description of the drawings]
1A to 1G are cross-sectional views showing an example of a method of manufacturing a superconducting wire according to the present invention in the order of steps.
FIG. 2 is a cross-sectional view showing an example of a method for manufacturing a superconducting wire of the present invention.
FIG. 3 is an enlarged cross-sectional view showing an example of the superconducting wire of the present invention.
FIG. 4 is an enlarged cross-sectional view showing an example of a conventional internal reinforcing and stabilizing type Nb ₃ Sn-based superconducting wire.
FIGS. 5A to 5G are cross-sectional views showing a method of manufacturing a conventional internal reinforcing and stabilizing type Nb ₃ Sn superconducting wire in the order of steps.
[Explanation of symbols]
30 ... Core material, 31 ... Tube, 34 ... Composite, 35 ... Tube, 36 ... Primary strand, 37 ... Tube, 38 ... Secondary Wire, 42 ... Diffusion prevention tube, 43 ... Tube, 44 ... Reinforcement tube, 51 ... Superconducting wire, 52 ... Core, 53 ... Diffusion prevention layer, 54 ... Cushion layer, 55 ... reinforcing layer, 56 ... stabilization layer.

Claims

Superconductivity in which a diffusion prevention layer made of Ta or Nb is provided on the outer periphery of a core portion made of an alloy-based superconductor or a core portion made of a material that becomes a superconductor by heat treatment, and a reinforcing layer made of a Cu-Nb alloy is provided on the outer periphery In the method of manufacturing a wire, after forming a diffusion prevention layer made of Ta or Nb on the outer periphery of the core portion, the outer periphery of the diffusion prevention layer is covered with a cushion material made of Cu, and further, a Cu-Nb alloy is put on the outer periphery of the cushion material A method for producing a superconducting wire, comprising the step of applying a diameter reduction process after covering a reinforcing material comprising:

The method for manufacturing a superconducting wire according to claim 1, wherein the thickness of the cushion material is 1.5% or more of the superconducting wire diameter.

A diffusion prevention layer made of Ta or Nb is provided on the outer periphery of the core made of an alloy-based superconductor or a core made of a material that becomes a superconductor by heat treatment, and a reinforcing layer made of a Cu-Nb alloy is provided on the outer periphery. A superconducting wire, wherein a cushion layer made of Cu is interposed between the diffusion preventing layer and the reinforcing layer.