JPWO2006129540A1 - Nb-Al-based superconducting wire having strongly adhered copper plating stabilizer and method for producing the same - Google Patents
Nb-Al-based superconducting wire having strongly adhered copper plating stabilizer and method for producing the same Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
- C25D7/06—Wires; Strips; Foils
- C25D7/0607—Wires
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- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/10—Electroplating with more than one layer of the same or of different metals
- C25D5/12—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/34—Pretreatment of metallic surfaces to be electroplated
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N60/00—Superconducting devices
- H10N60/01—Manufacture or treatment
- H10N60/0184—Manufacture or treatment of devices comprising intermetallic compounds of type A-15, e.g. Nb3Sn
Abstract
過飽和固溶体の状態にあるＮｂ−Ａｌ系線材の外周表面に中間層としてのＮｉ皮膜を介して安定化材としてのＣｕ皮膜が密着形成されてなるＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材であり、液体Ｇａ中で冷却して得られる過飽和固溶体の状態にあるＮｂ−Ａｌ系線材から、
（ａ）前記Ｎｂ−Ａｌ系線材の表面に付着したＧａ残滓を除去する工程；
（ｂ）工程（ａ）で得られる、表面のＧａ残滓が除去されたＮｂ−Ａｌ系線材を、該Ｎｂ−Ａｌ系線材を不動態化させない条件下で脱脂処理し、ついで酸洗浄処理する工程；
（ｃ）工程（ｂ）で得られる、酸洗浄処理されたＮｂ−Ａｌ系線材の表面を、ニッケルストライク浴を用いて、Ｎｉで電気めっきする工程；および
（ｄ）工程（ｃ）で得られる、Ｎｉで電気めっきされたＮｂ−Ａｌ系線材の表面を、Ｃｕで電気めっきする工程
を経て製造することができ、このＮｂ−Ａｌ系超伝導線材を用いて、核融合炉用マグネット、加速器用マグネット、高分解能を有する核磁気共鳴（ＮＭＲ）用マグネットに有用なＮｂ３Ａｌ化合物系超伝導線材を工業的に有利に製造できる。
【選択図】なし
Cu film as a stabilizing material is formed tightly adhered becomes Nb 3 Al compound transformation prior to Nb-Al based superconductor through the Ni film as the intermediate layer on the outer circumferential surface of the Nb-Al-based wire in a supersaturated solid solution A wire, which is a Nb-Al wire in a supersaturated solid solution state obtained by cooling in liquid Ga,
(A) a step of removing Ga residue attached to the surface of the Nb-Al-based wire rod;
(B) A step of degreasing the Nb-Al-based wire rod from which Ga residues on the surface have been removed obtained in step (a) under conditions that do not passivate the Nb-Al-based wire rod, and then subject to acid cleaning treatment. ;
(C) A step of electroplating the surface of the acid-cleaned Nb-Al-based wire obtained in step (b) with Ni using a nickel strike bath; and (d) obtained in step (c). , The surface of Nb-Al-based wire material electroplated with Ni can be manufactured through a step of electroplating with Cu. Using this Nb-Al-based superconducting wire material, a magnet for a fusion reactor, an accelerator Industrially, it is possible to industrially produce a Nb 3 Al compound-based superconducting wire useful for a magnet and a magnet for nuclear magnetic resonance (NMR) having high resolution.
[Selection diagram] None
Description
本発明は、核融合炉用マグネット、加速器用マグネット、高分解能を有する核磁気共鳴（ＮＭＲ）用マグネットなどに応用されるＮｂ３Ａｌ系の超伝導線材の製造方法、およびＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材の製造方法に関する。INDUSTRIAL APPLICABILITY The present invention relates to a method for manufacturing a Nb 3 Al-based superconducting wire applied to a magnet for a nuclear fusion reactor, a magnet for an accelerator, a magnet for nuclear magnetic resonance (NMR) having a high resolution, and a Nb 3 Al compound before transformation. The present invention relates to a method for manufacturing a Nb-Al-based superconducting wire.
従来、Ｎｂ３Ｓｎ、Ｖ３Ｇａ、Ｎｂ３Ｔｉよりも臨界温度（Ｔｃ）及び上部臨界磁界（ＨＣ２）が高く、しかも線材の製造コストが低減されると期待されるＮｂ３Ａｌ系の超伝導の線材化研究が、１９７０年代後半から数多く行われてきた。しかし、Ｎｂ３Ａｌは、従来では線材化が難しいという重大な問題点があって、その実用化が阻まれてきた。
近年、特許文献１に見られるように急熱急冷処理法によって線材化の見通しが得られつつある。この方法の要点は、次の通りである。まずＮｂとＡｌとからなるフィラメントを事前に製造しておき、次にこのフィラメントをＮｂパイプあるいはＴａパイプ中に詰め、静水圧押出しにより線材（ＮｂＡｌ／Ｎｂ複合体あるいはＮｂＡｌ／Ｔａ複合体＝前駆体）を成形する。しかる後に、通電加熱して一気に２０００℃程度に昇温し、直ちに液体Ｇａ浴で急冷してＮｂ−Ａｌの過飽和固溶体となす。次いで適切な形状に加工した後、８００℃程度の温度でＮｂ３Ａｌに変態させて製造するというものである。特許文献２には、前駆体の製造方法が詳細に記載されている。 Conventionally, Nb 3 Sn, V 3 Ga , critical temperature than Nb 3 Ti (Tc) and the upper critical magnetic field (H C2) is high and Nb 3 Al-based production cost of the wire is expected to be reduced super Many studies have been conducted on conductive wire rods since the late 1970s. However, Nb 3 Al has a serious problem that it is difficult to form a wire rod in the related art, and its practical use has been hindered.
In recent years, as seen in Patent Document 1, the prospect of forming a wire rod is being obtained by a rapid heating and quenching method. The main points of this method are as follows. First, a filament composed of Nb and Al is manufactured in advance, then this filament is packed in an Nb pipe or a Ta pipe, and a wire rod (NbAl/Nb composite or NbAl/Ta composite=precursor) is prepared by hydrostatic extrusion. ) Is molded. Then, it is electrically heated to a temperature of about 2000° C. at once, and immediately quenched in a liquid Ga bath to form a supersaturated solid solution of Nb-Al. Then, after being processed into an appropriate shape, it is transformed into Nb 3 Al at a temperature of about 800° C. to be manufactured. Patent Document 2 describes in detail a method for producing a precursor.
図１および図２には代表的なマルチ線材（以下、ＮｂＡｌ／Ｎｂ複合線材ともいう。一般に、前駆体と称される）の製造方法を示す。また、図３にはマルチ線材からさらに、急熱急冷装置によりＮｂ−Ａｌへと過飽和固溶体化させる工程を示している。ここで急熱急冷・変態化法とは、線材温度が２０００℃近い高温にもなる特殊な製法である。
ところでＮｂ自体は、常伝導状態での電気抵抗が大きく、クエンチ時のホットスポットの抑制や線材の発熱溶損防止のための安定化材としての機能を期待できない。この為に超伝導線材の実用化に於いて何某かの安定化材の複合が必要条件となっている。1 and 2 show a method for producing a typical multi-wire material (hereinafter, also referred to as NbAl/Nb composite wire material, generally referred to as a precursor). Further, FIG. 3 shows a step of further converting the multi-wire material into a supersaturated solid solution into Nb-Al by a rapid heating and quenching device. Here, the rapid heating and quenching/transformation method is a special manufacturing method in which the wire temperature is as high as 2000°C.
By the way, Nb itself has a large electric resistance in the normal conduction state, and cannot be expected to have a function as a stabilizing material for suppressing hot spots during quenching and preventing heat melting damage of the wire. For this reason, a composite of some stabilizers is a necessary condition for practical use of the superconducting wire.
Ｎｂ−Ａｌ系線材の安定化材としては銅、銀等の熱伝導性の良い金属とその合金が多用されており、安定化材の複合化方法としては内部安定化法（例えば特許文献３参照）と外部安定化法とがある。後者の外部安定化法は安定化材比の自由度が大きく、直接冷媒と接するために冷却効率が高いという利点がある。しかし先に述べた急熱急冷・変態化法に於ける工法上の制約から線材温度が２０００℃にもなるために融点がこの温度よりも低い銅等の安定化材を、前駆体の製作過程で、事前に被覆して置くことが出来ないという問題がある。 As the stabilizer for the Nb-Al-based wire, a metal having good thermal conductivity such as copper and silver and its alloy are often used, and as a method for compounding the stabilizer, an internal stabilization method (for example, see Patent Document 3). ) And external stabilization method. The latter external stabilization method has the advantage that it has a high degree of freedom in the ratio of stabilizers and has a high cooling efficiency because it directly contacts the refrigerant. However, since the wire temperature can reach 2000°C due to the restrictions on the method used in the rapid heating and quenching/transformation method described above, a stabilizing material such as copper having a melting point lower than this temperature is used in the precursor manufacturing process. However, there is a problem that it cannot be covered and placed in advance.
この問題を解決するために提案されている方法として、特許文献４にその詳細が開示されているが、図４に例示した銅クラッド加工法の如く、圧延加工による物理的な力で安定化材を複合させる方法がある。しかしながらこの方法では、円形断面の線材が出来ないことに加え、Ｎｂと圧接される銅シートとの界面の一様な密着性の信頼性が確保出来ず、Ｎｂと安定化材との接触抵抗増大に関与する界面からの剥離現象を呈し易いという基本的な問題が存在する。 As a method proposed for solving this problem, the details thereof are disclosed in Patent Document 4, but as in the copper clad processing method illustrated in FIG. 4, a stabilizing material is used by a physical force by rolling. There is a method of compounding. However, in this method, in addition to the fact that a wire having a circular cross section cannot be obtained, the reliability of uniform adhesion at the interface between Nb and the copper sheet to be pressure-welded cannot be ensured, and the contact resistance between Nb and the stabilizing material increases. There is a fundamental problem that the phenomenon of peeling from the interface, which is involved in the, is likely to occur.
この問題に鑑みて、特許文献５及び非特許文献１では、急熱急冷・変態化法で製作されたＮｂ−Ａｌ系超伝導線材に対して、安定化材などの金属の必要膜厚の全てをイオンプレーティング法で形成させるという提案と、イオンプレーティング法によって、Ｎｂ表面との密着性確保の手段として金属薄膜を第１の安定化材層として形成させ、しかる後に公知の電気銅めっき技術などで第２の安定化材層を肉盛りする方法の提案がなされている。真空チャンバーを利用するこの種の手法は、酸化・不動態化し易いＮｂに対してその表面に形成する安定化材の密着性を確保するという点では好ましいものであると考えられる。しかしその一方で安定化材の成膜速度が比較的遅く、長尺化対応が難しいといった制約が生産性に乏しいという現実的な問題を露呈している。つまり、高価且つバッチ処理を基本とする真空チャンバーを利用するが為に最終的に必要とする超伝導線材を安定的、且つ経済的に生産するという点に於いて適切な方法とはなり得ない。 In view of this problem, in Patent Document 5 and Non-Patent Document 1, for Nb-Al-based superconducting wire produced by the rapid heating and quenching/transformation method, all required film thicknesses of metals such as stabilizers are required. Is formed by an ion plating method, and a metal thin film is formed as a first stabilizing material layer as a means for ensuring adhesion with the Nb surface by the ion plating method, and then a known electrolytic copper plating technique is used. For example, a method of overlaying the second stabilizing material layer has been proposed. This type of method using a vacuum chamber is considered to be preferable in terms of ensuring the adhesion of the stabilizing material formed on the surface of Nb that is easily oxidized and passivated. On the other hand, however, the film forming speed of the stabilizing material is relatively slow, and the limitation that it is difficult to cope with the lengthening of the stabilizer exposes a practical problem of poor productivity. In other words, it cannot be an appropriate method in terms of stably and economically producing the superconducting wire which is finally needed because the vacuum chamber which is expensive and uses a batch process as a basis is used. .
一方、特許文献６では当該超伝導線材に対し、Ｎｂ表面の不動態膜（酸化膜）を効果的に除去したり、洗浄工程で使用する洗浄水の脱気処理を行うなどの処理、あるいは前処理に用いた酸類と成分的に類似せしめためっき液を利用することによってＮｂと安定化材の銅あるいは銀めっきなどを密着させる方法を提案している。電気めっきの手法を利用するという点では量産性に優れた安定化材の形成方法であるが、このような手立てを講じても、安定化材を形成した後、Ｎｂ３Ａｌ変態させる８００℃程度の二次熱処理（ベーキング）工程に至るまでに行う諸々の加工工程、例えば曲げ加工、より線加工、再度のダイス伸線加工などに耐えうる実用的密着力には達しておらず未だに実用に至っていない。なお、付け加えれば二次熱処理に先立ち、安定化材の被覆を先行する理由は、Ｎｂ−Ａｌ過飽和固溶体の状態から脆いＮｂ３Ａｌ化合物となって、その後の諸々の加工が事実上不可能となることにある。On the other hand, in Patent Document 6, the superconducting wire is treated to effectively remove the passivation film (oxide film) on the Nb surface or to degas the cleaning water used in the cleaning step, or A method has been proposed in which Nb and copper or silver plating as a stabilizer are brought into close contact with each other by using a plating solution that is similar in composition to the acids used in the treatment. Although it is a method of forming a stabilizing material that is excellent in mass productivity in that it uses the electroplating method, even if such a measure is taken, the stabilizing material is formed and then the Nb 3 Al transformation is performed at about 800°C. The secondary adhesion heat treatment (baking) process, such as various processing steps such as bending, twisting and re-die drawing, has not yet reached a practical level of adhesion and is still in practical use. Not in. Prior to the secondary heat treatment if addition, whereas the reason why a preceding coating of stabilizing material is a brittle Nb 3 Al compound from the state of Nb-Al supersaturated solid solution, subsequent various processing becomes virtually impossible Especially.
また、特許文献７には、マルチ線材に外部安定化材をめっきするとの記載がある。しかしながら、その具体的な手法についての詳細は一切開示されていない。 Further, Patent Document 7 describes that an external stabilizing material is plated on a multi-wire material. However, no details about the specific method are disclosed.
さらに特許文献８では、Ｎｂ３Ａｌ芯線の外周にＮｂ層（下層）、さらにその外周に銅や銀の安定化材層（上層）を有する超伝導線材において、Ｎｂ表面と銅や銀の安定化材層との間にＮｉ、Ｓｎ、Ａｇ、Ａｕ、Ｐｔ、Ｐｄ単体もしくはこれらの合金からなる中間膜を備えたＮｂ３Ａｌ超伝導線とその製造方法が開示されている。なお、中間膜は電気めっき法、無電解めっき、蒸着法で形成させるとしており、中間膜と下層のＮｂ表面及び上層の安定化材とを密着させるために超伝導線材の機能喪失温度以下で熱処理して拡散させるという工法を提案している。
しかしながら、特許文献８の技術内容には不明なことも多く、明細書の記述では芯線を束ねたその表面にＮｂを電気めっき、無電解めっき、蒸着等で被覆した後に、さらに、その表面に中間膜を被覆するとしている。原理的にＮｂの無電解めっきは不可能であり、また水溶液をベースとした公知のＮｂの電気めっき技術は存在しない。さらに蒸着法でのＮｂの被覆も些か実現性に無理がある。本発明者らが電気めっき技術に限って技術内容を追試して見ると、提案されている方法には重大な欠点があることを発見した。例えば中間膜としてＳｎ、Ａｇ、Ａｕなどを用いる妥当性の有無に問題がある。つまり、これらの金属は、元々Ｎｂと反応するよりも安定化材の銅、銀との反応性が高く、速やかに安定化材側に拡散する。これらの中間層を電気めっき、無電解めっき法によって被覆し得るとしても、安定化材の被覆時やその後の加熱時に安定化材に膨れを生じ易い。さらに一見健全に見える安定化材が被覆できたとしても９０°曲げ試験により、僅か１回の折り曲げで剥離したりする。その理由はＮｂの表面が極めて不動態化し易く、この状態に於いてＮｂとの拡散反応層を形成して結合するとは考え難い。さらに一切の開示もないが、残るＮｉ、Ｐｔ、Ｐｄとその合金にしても中間膜の被覆に当たり、Ｎｂ表面の不動態膜の除去とその後の活性面の維持が容易な蒸着法等を採用しない限り、これらを密着させることが出来ない。つまり無電解めっき法や電気めっき法に於いてはＮｂ表面の不動態膜除去方法やさらには選定しためっき液（浴）の妥当性の有無の問題が一切考慮されていない。またいずれの中間膜被覆方法でも共通の課題となるが、Ｎｂ−Ａｌ超伝導線材前駆体の製造時に線材表面に付着・拡散しているＧａ残滓の除去方法の適否がその後に形成する皮膜の密着性に大きく影響することを本発明者らは知見したが、これらに関する開示は一切為されていない。以上のように工業的に見て効果的な銅安定化材の被覆技術が未だ完成されておらず、これが、Ｎｂ３Ａｌ系の超伝導線材が未だに実用に供せられていない理由となっているものと考えられる。
However, the technical content of Patent Document 8 is often unclear, and in the description of the specification, the surface of the bundled core wires is coated with Nb by electroplating, electroless plating, vapor deposition, or the like, and then the intermediate surface is formed. It is said to cover the membrane. In principle, electroless plating of Nb is not possible, and there is no known Nb electroplating technique based on an aqueous solution. Further, the coating of Nb by the vapor deposition method is slightly unrealistic. The present inventors have found that the proposed method has a serious drawback when the technical contents are additionally examined only for the electroplating technology. For example, there is a problem in the validity of using Sn, Ag, Au, etc. as the intermediate film. That is, these metals have a higher reactivity with the stabilizing materials copper and silver than they originally react with Nb, and diffuse quickly to the stabilizing material side. Even if these intermediate layers can be coated by electroplating or electroless plating, the stabilizing material is likely to swell during coating of the stabilizing material and subsequent heating. Further, even if the stabilizing material, which seems to be sound at first sight, can be coated, the 90° bending test causes peeling with only one bending. The reason is that the surface of Nb is extremely passivated, and it is difficult to consider that a diffusion reaction layer with Nb is formed and bonded in this state. Furthermore, although there is no disclosure at all, even with the remaining Ni, Pt, Pd and their alloys, the intermediate film is covered, and a vapor deposition method or the like that easily removes the passivation film on the Nb surface and maintains the active surface thereafter is not adopted. As long as they can't be in close contact. That is, in the electroless plating method and the electroplating method, no consideration is given to the method of removing the passivation film on the Nb surface, and further the problem of the validity of the selected plating solution (bath). Also, although any intermediate film coating method has a common problem, the suitability of the method for removing the Ga residue that has adhered to and diffused on the surface of the Nb-Al superconducting wire precursor during the production of the Nb-Al superconducting wire precursor is due to the adhesion of the film formed thereafter. The present inventors have found that the effect on sex is greatly affected, but no disclosure regarding these is made. As described above, the coating technology of the copper stabilizing material which is industrially effective has not been completed yet, and this is the reason why the Nb 3 Al superconducting wire has not been put to practical use yet. It is thought that there is.
本発明は、銅安定化材が強固に密着して被覆された、実用に耐えうる新規なＮｂ−Ａｌ系超伝導線材を提供すること、および、そのようなＮｂ−Ａｌ系超伝導線材を簡便かつ経済的に製造できる工業的に有利な製造方法を提供することを課題とする。 The present invention provides a novel Nb-Al-based superconducting wire that can be practically used, in which a copper stabilizing material is tightly adhered and coated, and such an Nb-Al-based superconducting wire can be easily provided. An object of the present invention is to provide an industrially advantageous manufacturing method that can be manufactured economically.
本発明者らは、まず特許文献６に提案される方法の追試と非特許文献２のＮｂに関する公知の電気めっき手法の追試を開始した。この際、急熱・急冷法に付随するＮｂ−Ａｌ系超伝導線材の製法上の必然性からＮｂ外層材の表面に残存するＧａ残滓の除去法は取り敢えず別途に考慮することとし、Ｎｂ材に対する銅安定化材の密着性を確保することを課題として被覆工程の確立に注力した。なお、試験に当たっては市販の純ニオブ板をその評価用として利用した。 The present inventors first started the additional test of the method proposed in Patent Document 6 and the known electroplating method for Nb of Non-Patent Document 2. At this time, the method of removing Ga residue remaining on the surface of the Nb outer layer material is taken into consideration separately from the necessity of manufacturing the Nb-Al-based superconducting wire accompanying the rapid heating/quenching method. We focused on the establishment of the coating process, with the aim of ensuring the adhesion of the stabilizer. In the test, a commercially available pure niobium plate was used for evaluation.
特許文献６に提案する方法は、実質的にＮｂ表面の酸化皮膜の膜厚を制御して、フッ化水素酸、ホウフッ化銅液を利用した銅による導電性金属膜の形成と、また要すれば大気隔離や導電性金属膜形成後、あるいは導電性金属膜の表面に銅安定化材を被覆する中途段階で水素除去を目的として５０〜６００℃での加熱処理により銅めっき皮膜を密着させるというものである。本発明者らが追試し、ＪＩＳ−Ｈ−８５０４（密着性試験方法）に規定される「曲げ試験方法」によって評価すると、僅か１回の曲げにも耐えきれず銅めっき皮膜が剥離した。また銅めっき後に６００℃で加熱処理すると銅皮膜に膨れを生じ、熱処理による脱水素の密着性に及ぼす改善効果は全く見られない。 The method proposed in Patent Document 6 substantially controls the film thickness of the oxide film on the Nb surface to form a conductive metal film of copper using a hydrofluoric acid or copper borofluoride solution, and also requires For example, it is said that the copper plating film is adhered by heat treatment at 50 to 600° C. for the purpose of removing hydrogen after air isolation or formation of the conductive metal film, or in the middle of coating the surface of the conductive metal film with the copper stabilizing material. It is a thing. When the inventors of the present invention made additional tests and evaluated by the "bending test method" specified in JIS-H-8504 (adhesion test method), the copper plating film was peeled off because it could not withstand even a single bending. Further, when heat-treated at 600° C. after copper plating, the copper film swells, and no improvement effect on the adhesion of dehydrogenation by heat treatment is observed.
一方、非特許文献２には２種類の手法の記述がある。一つは、フッ化水素酸の溶液中での交流電解処理、水洗後、硝酸−フッ化水素酸の溶液への浸漬、水洗、鉄めっきと続き、最終的に７００℃で１時間の熱処理によりめっきを密着させるというものである。残りの別法は、水酸化ナトリウム溶液中での陽極処理、水洗、ウッドニッケルストライク浴でのめっき、続いて鉄ないしニッケルめっきと被覆し、最後に赤熱加熱でめっきを密着させようというものである。いずれも追試の結果では、特許文献６の結果と同様に銅安定化材そのものが密着しない。 On the other hand, Non-Patent Document 2 describes two types of methods. One is AC electrolytic treatment in a hydrofluoric acid solution, followed by washing with water, followed by immersion in a nitric acid-hydrofluoric acid solution, washing with water, and iron plating, and finally by heat treatment at 700°C for 1 hour. It is to bring the plating into close contact. The remaining alternatives are anodizing in sodium hydroxide solution, washing with water, plating in a wood nickel strike bath, followed by coating with iron or nickel plating, and finally using red heat to bring the plating into close contact. . In both cases, the copper stabilizer itself does not adhere to the results of the additional test, as in the case of Patent Document 6.
本発明者らは、さらに検討を重ねた結果、液体Ｇａ中で冷却して得られる過飽和固溶体の状態にあるＮｂ−Ａｌ系超伝導線材から、
（ａ）前記Ｎｂ−Ａｌ系線材の表面に付着したＧａ残滓を除去する工程；
（ｂ）工程（ａ）で得られる、表面のＧａ残滓が除去されたＮｂ−Ａｌ系線材を、該Ｎｂ−Ａｌ系線材を不動態化させない条件下で脱脂処理し、ついで酸洗浄処理する工程；
（ｃ）工程（ｂ）で得られる、酸洗浄処理されたＮｂ−Ａｌ系線材の表面を、ニッケルストライク浴を用いて、Ｎｉで電気めっきする工程；
（ｄ）工程（ｃ）で得られる、Ｎｉで電気めっきされたＮｂ−Ａｌ系線材の表面を、Ｃｕで電気めっきする工程
さらに好ましくは、
（ｅ）工程（ｄ）で得られる、Ｃｕで電気めっきされたＮｂ−Ａｌ系線材を、酸化防止雰囲気下４００〜７００℃でベーキングする工程
を経てＮｂ3Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材を製造する方法を開発し、さらに、該Ｎｂ3Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材を、７００℃以上の温度で熱処理する工程を経て、Ｎｂ３Ａｌ化合物系超伝導線材を製造する方法を開発した。そして、かかる方法およびそれにより得られたＮｂ３Ａｌ化合物系超伝導線材が、前記した従来の課題を一挙に解決できることを見出し、さらに検討を重ねて本発明を完成させるに至った。As a result of further studies, the inventors of the present invention have found that Nb-Al-based superconducting wire in a supersaturated solid solution state obtained by cooling in liquid Ga
(A) a step of removing Ga residue attached to the surface of the Nb-Al-based wire rod;
(B) A step of degreasing the Nb-Al-based wire rod from which Ga residues on the surface have been removed obtained in step (a) under conditions that do not passivate the Nb-Al-based wire rod, and then subject to acid cleaning treatment. ;
(C) A step of electroplating the surface of the acid-cleaned Nb-Al-based wire obtained in step (b) with Ni using a nickel strike bath;
(D) A step of electroplating the surface of the Ni-electroplated Nb-Al-based wire obtained in step (c) with Cu, more preferably,
(E) obtained in step (d), the Nb-Al-based wire is electroplated with Cu, through the step of baking under 400 to 700 ° C. atmosphere antioxidant Nb 3 Al compound transformation prior to Nb-Al system than developed a method for producing a conductive wire, further, the Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire, through a step of heat treatment at 700 ° C. or higher, the Nb 3 Al compound-based superconducting wire A manufacturing method was developed. Then, it was found that such a method and the Nb 3 Al compound-based superconducting wire obtained by the method can solve the above-mentioned conventional problems all at once, and further studies have been completed to complete the present invention.
すなわち、本発明は、
［１］ 過飽和固溶体の状態にあるＮｂ−Ａｌ系線材の外周表面に中間層としてのＮｉ皮膜を介して安定化材としてのＣｕ皮膜が密着形成されてなるＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材、
［２］ 前記過飽和固溶体の状態にあるＮｂ−Ａｌ系線材の表面にＧａ残滓が実質的に存在しない前項［１］に記載のＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材、
［３］ Ｃｕ皮膜の厚さが４０μｍ以上である前項［１］に記載のＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材、
［４］ 線径が０．１ｍｍ以上である前項［１］に記載のＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材、
［５］ Ｎｉ皮膜およびＣｕ皮膜が電気めっき皮膜である前項［１］に記載のＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材、
［６］ 液体Ｇａ中で冷却して得られる過飽和固溶体の状態にあるＮｂ−Ａｌ系線材から、Ｎｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材を製造する方法であって、
（ａ）前記Ｎｂ−Ａｌ系線材の表面に付着したＧａ残滓を除去する工程；
（ｂ）工程（ａ）で得られる、表面のＧａ残滓が除去されたＮｂ−Ａｌ系線材を、該Ｎｂ−Ａｌ系線材を不動態化させない条件下で脱脂処理し、ついで酸洗浄処理する工程；
（ｃ）工程（ｂ）で得られる、酸洗浄処理されたＮｂ−Ａｌ系線材の表面を、ニッケルストライク浴を用いて、Ｎｉで電気めっきする工程；および
（ｄ）工程（ｃ）で得られる、Ｎｉで電気めっきされたＮｂ−Ａｌ系線材の表面を、Ｃｕで電気めっきする工程
を含むことを特徴とするＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材の製造方法、
［７］ 前記（ａ）〜（ｄ）の工程に加えて、
（ｅ）工程（ｄ）で得られる、Ｃｕで電気めっきされたＮｂ−Ａｌ系線材を、酸化防止雰囲気下４００〜７００℃でベーキングする工程
を含むことを特徴とする前項［６］に記載の製造方法、
［８］ 工程（ａ）におけるＧａ残滓の除去を、研磨手段によって行う前項［６］に記載の製造方法、
［９］ 工程（ｂ）における不動態化させない条件が、Ｎｂ−Ａｌ系線材の表面を実質的に酸化させない条件である前項［６］に記載の製造方法、
［１０］ 工程（ｃ）におけるニッケルストライク浴が、ニッケルの塩化物、硫酸塩およびスルファミン酸塩からなる群から選ばれる１種または２種以上のニッケル塩と、塩酸、硫酸またはスルファミン酸とを含んでなるｐＨ２以下の液である前項［６］に記載の製造方法、
［１１］ 工程（ｄ）における電気めっきをＣｕの皮膜の厚さが４０μｍ以上となるように行う前項［６］に記載の製造方法、
［１２］ 工程（ｅ）におけるベーキングを、酸化防止雰囲気下５００〜６５０℃で行う前項［６］に記載の製造方法、
［１３］ Ｎｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材の線径が０．１ｍｍ以上である前項［６］に記載の製造方法、
［１４］ 液体Ｇａ中で冷却して得られる過飽和固溶体の状態にあるＮｂ−Ａｌ系線材から、Ｎｂ３Ａｌ化合物系超伝導線材を製造する方法であって、
（ａ）前記Ｎｂ−Ａｌ系超伝導線材の表面に付着したＧａ残滓を除去する工程；
（ｂ）工程（ａ）で得られる、表面のＧａ残滓が除去されたＮｂ−Ａｌ系線材を、該Ｎｂ−Ａｌ系線材を不動態化させない条件下で脱脂処理し、ついで酸洗浄処理する工程；
（ｃ）工程（ｂ）で得られる、酸洗浄処理されたＮｂ−Ａｌ系線材の表面を、ニッケルストライク浴を用いて、Ｎｉで電気めっきする工程；
（ｄ）工程（ｃ）で得られる、Ｎｉで電気めっきされたＮｂ−Ａｌ系線材の表面を、Ｃｕで電気めっきする工程；
（ｅ）工程（ｄ）で得られる、Ｃｕで電気めっきされたＮｂ−Ａｌ系線材を、酸化防止雰囲気下４００〜７００℃でベーキングする工程；および
（ｆ）工程（ｅ）で得られる、ベーキングされたＮｂ−Ａｌ系線材を、７００℃以上の温度で熱処理する工程
を含むことを特徴とするＮｂ３Ａｌ化合物系超伝導線材の製造方法、
［１５］ 工程（ａ）におけるＧａ残滓の除去を、研磨手段によって行う前項［１４］に記載の製造方法、
［１６］ 工程（ｂ）における不動態化させない条件が、Ｎｂ−Ａｌ系線材の表面を実質的に酸化させない条件である前項［１４］に記載の製造方法、
［１７］ 工程（ｃ）におけるニッケルストライク浴が、ニッケルの塩化物、硫酸塩およびスルファミン酸塩からなる群から選ばれる１種または２種以上のニッケル塩と、塩酸、硫酸またはスルファミン酸とを含んでなるｐＨ２以下の液である前項［１４］に記載の製造方法、
［１８］ 工程（ｄ）における電気めっきをＣｕの皮膜の厚さが４０μｍ以上となるように行う前項［１４］に記載の製造方法。
［１９］ 工程（ｅ）におけるベーキングを、酸化防止雰囲気下５００〜６５０℃で行う前項［１４］に記載の製造方法。
［２０］ 工程（ｆ）における熱処理を、７００℃〜１０００℃の温度で行う前項［１４］に記載の製造方法
に関する。That is, the present invention is
[1] Nb 3 Al compound Nb-Al before transformation, in which a Cu film as a stabilizer is adhered to the outer peripheral surface of an Nb-Al-based wire rod in a supersaturated solid solution state via a Ni film as an intermediate layer Superconducting wire,
[2] Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire according to item [1] Ga residues are substantially absent in the Nb-Al-based wire surface in the state of the supersaturated solid solution,
[3] The Nb—Al-based superconducting wire before the Nb 3 Al compound transformation according to the above [1], wherein the thickness of the Cu coating is 40 μm or more.
[4] Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire according to item [1] is the wire diameter is 0.1mm or more,
[5] Ni film and Cu film is electroplated film preceding [1] Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire according to,
[6] from Nb-Al-based wire in a supersaturated solid solution obtained by cooling in liquid Ga, a method for producing a Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire,
(A) a step of removing Ga residue attached to the surface of the Nb-Al-based wire rod;
(B) A step of degreasing the Nb-Al-based wire rod from which Ga residues on the surface have been removed obtained in step (a) under conditions that do not passivate the Nb-Al-based wire rod, and then subject to acid cleaning treatment. ;
(C) A step of electroplating the surface of the acid-cleaned Nb-Al-based wire obtained in step (b) with Ni using a nickel strike bath; and (d) obtained in step (c). a method for producing a surface of the Nb-Al-based wire is electroplated with Ni, Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire, which comprises a step of electroplating with Cu,
[7] In addition to the steps (a) to (d),
(E) A step of baking the Cu-electroplated Nb-Al-based wire rod obtained in step (d) at 400 to 700° C. in an oxidation-preventing atmosphere, as described in the above item [6]. Production method,
[8] The production method according to the above item [6], wherein the Ga residue in the step (a) is removed by a polishing means.
[9] The production method according to the above item [6], wherein the condition that does not passivate the step (b) is a condition that does not substantially oxidize the surface of the Nb-Al-based wire.
[10] The nickel strike bath in step (c) contains one or more nickel salts selected from the group consisting of nickel chloride, sulfate and sulfamate, and hydrochloric acid, sulfuric acid or sulfamic acid. The production method according to the above [6], which is a liquid having a pH of 2 or less,
[11] The production method according to the above item [6], wherein the electroplating in the step (d) is performed so that the thickness of the Cu film is 40 μm or more.
[12] The production method according to the above item [6], wherein the baking in the step (e) is performed at 500 to 650° C. in an antioxidant atmosphere.
[13] The manufacturing method according to the above item [6], wherein the Nb-Al-based superconducting wire before the Nb 3 Al compound transformation has a wire diameter of 0.1 mm or more.
[14] A method for producing an Nb 3 Al compound-based superconducting wire from an Nb-Al-based wire in a supersaturated solid solution state obtained by cooling in liquid Ga,
(A) a step of removing Ga residue attached to the surface of the Nb-Al superconducting wire;
(B) A step of degreasing the Nb-Al-based wire rod from which Ga residues on the surface have been removed obtained in step (a) under conditions that do not passivate the Nb-Al-based wire rod, and then subject to acid cleaning treatment. ;
(C) A step of electroplating the surface of the acid-cleaned Nb-Al-based wire obtained in step (b) with Ni using a nickel strike bath;
(D) A step of electroplating the surface of the Ni-electroplated Nb-Al-based wire obtained in step (c) with Cu;
(E) a step of baking the Cu-electroplated Nb-Al-based wire obtained in step (d) at 400 to 700° C. in an antioxidant atmosphere; and (f) a baking obtained in step (e). A method of manufacturing a Nb 3 Al compound-based superconducting wire, comprising the step of heat-treating the prepared Nb-Al-based wire at a temperature of 700° C. or higher,
[15] The production method according to the above item [14], wherein the Ga residue is removed by a polishing means in the step (a).
[16] The production method according to the above item [14], wherein the condition that does not passivate the step (b) is a condition that does not substantially oxidize the surface of the Nb-Al-based wire.
[17] The nickel strike bath in step (c) contains one or more nickel salts selected from the group consisting of nickel chloride, sulfate and sulfamate, and hydrochloric acid, sulfuric acid or sulfamic acid. The production method according to the above [14], which is a liquid having a pH of 2 or less,
[18] The production method according to the above item [14], wherein the electroplating in the step (d) is performed so that the thickness of the Cu film is 40 μm or more.
[19] The production method according to the above item [14], wherein the baking in step (e) is performed at 500 to 650° C. in an antioxidant atmosphere.
[20] The manufacturing method according to the above item [14], wherein the heat treatment in the step (f) is performed at a temperature of 700°C to 1000°C.
本発明のＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材においては、Ｎｂ−Ａｌ系線材の表面にＮｉ皮膜を介して銅安定化材が強固に密着しているので、これを用いることにより、銅安定化材が強固に密着しているために高い臨界温度（Ｔｃ）と上部臨界磁界（ＨＣ２）を示すＮｂ３Ａｌ化合物系超伝導線材が得られる。
また、本発明の製造方法によれば、そのような銅安定化材が強固に密着した化合物変態前のＮｂ−Ａｌ系超伝導線材、ひいては高い臨界温度（Ｔｃ）と上部臨界磁界（ＨＣ２）を有する優れたＮｂ３Ａｌ化合物系超伝導線材を簡便かつ経済的に製造することができる。なぜならば、本発明の製造方法では、Ｎｂ−Ａｌ系線材への外部安定化材の被覆に於いて、不動態化し易い線材表面に強固に密着した銅安定化材を経済的かつ簡便な汎用の電気めっき技術のみで被覆できるからであり、それによって二次熱処理工程に移行する迄に必然的に派生する諸々の加工工程で付与される各種の作用応力に耐え得る銅安定化材の強固な密着性を実現できるからである。なお、Ｎｂ金属の具備する高い活性度がその表面に強固な不動態膜（酸化膜）を形成し、その存在が各種のめっき皮膜に要求される密着性確保の障害となることはよく知られている。また、安定化材の密着性という点では問題のないイオンプレーティング法による成膜手段を採用した従来方法と比較しても、イオンプレーティングの適用には真空チャンバーの利用が必須で生産性に難点を抱えるのに対し、本発明の製造方法では汎用性の高い電気めっき技術により銅安定化材を強固に密着できるので、工業的に有利である。In Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire of the present invention, since the copper stabilizer through the Ni film on the surface of the Nb-Al-based wire is firmly adhered to, the use of this As a result, an Nb 3 Al compound-based superconducting wire exhibiting a high critical temperature (Tc) and an upper critical magnetic field (H C2 ) because the copper stabilizing material is firmly adhered can be obtained.
Further, according to the production method of the present invention, such a copper stabilizing material is firmly adhered to the Nb-Al-based superconducting wire before compound transformation, and thus a high critical temperature (Tc) and an upper critical magnetic field ( HC2 ). It is possible to easily and economically produce an excellent Nb 3 Al compound-based superconducting wire having This is because, in the production method of the present invention, in coating the Nb-Al-based wire with the external stabilizer, the copper stabilizer firmly adhered to the surface of the wire that is easily passivated can be used economically and easily. This is because it can be coated only by electroplating technology, and by doing so, strong adhesion of the copper stabilizing material that can withstand various working stresses that are inevitably derived in various processing steps that are inevitably derived before the transition to the secondary heat treatment step. This is because it can realize It is well known that the high activity of Nb metal forms a strong passivation film (oxide film) on the surface, and its existence is an obstacle to securing the adhesion required for various plating films. ing. In addition, compared with the conventional method that uses a film forming means by the ion plating method, which does not have a problem in terms of adhesion of the stabilizer, the use of a vacuum chamber is indispensable for the application of ion plating, which increases productivity. In contrast to the drawbacks, the production method of the present invention is industrially advantageous because the copper stabilizer can be firmly adhered by the electroplating technique having high versatility.
１ キャブスタン
２ 液体Ｇａ浴
３ 送出しリール
４ 巻取りリール1 Cabstan 2 Liquid Ga bath 3 Delivery reel 4 Take-up reel
本発明のＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材（以下、「本発明のＮｂ−Ａｌ系超伝導線材」と略記することがある）は、過飽和固溶体の状態にあるＮｂ−Ａｌ系線材の外周表面に中間層としてのＮｉ皮膜を介して安定化材としてのＣｕ皮膜が密着形成されてなる線材である。Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire of the present invention (hereinafter, sometimes abbreviated as "Nb-Al-based superconducting wire of the present invention") is, Nb-Al in the state of a supersaturated solid solution This is a wire rod in which a Cu coating film as a stabilizing material is adhered to the outer peripheral surface of a system wire material via a Ni coating film as an intermediate layer.
本発明に用いられる過飽和固溶体の状態にあるＮｂ−Ａｌ系線材は、液体Ｇａ中で冷却して得ることができる過飽和固溶体の状態にあるＮｂ−Ａｌ系線材である。このＮｂ−Ａｌ系線材は、後述する熱処理により超伝導化合物であるＮｂ３Ａｌ化合物に変態するが、当該変態前においてもそれ自体超伝導性を示し得る。したがって、本明細書では便宜上「Ｎｂ−Ａｌ系超伝導線材」でなく「Ｎｂ−Ａｌ系線材」と表わすが、超伝導性を排除する意味ではない。また、前記Ｎｂ−Ａｌ系線材は、通常は液体Ｇａ中で冷却して得られるため、Ｇａ残滓が表面に付着しているが、本発明のＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材におけるＮｂ−Ａｌ系線材の表面、詳細にはＮｂ−Ａｌ系線材とＮｉ皮膜ないしＣｕ皮膜との間には、Ｇａ残滓が実質的に存在しないことが好ましい。Ｇａ残滓が実質的に存在しないようにするには、Ｎｉ皮膜の形成前にＧａ残滓を除去することが有効であり、これによりＮｉ皮膜ひいてはＣｕ皮膜がより強固にＮｂ−Ａｌ系線材の表面に密着する。The Nb-Al-based wire rod in the supersaturated solid solution state used in the present invention is an Nb-Al-based wire rod in the supersaturated solid solution state that can be obtained by cooling in liquid Ga. The Nb-Al-based wire is transformed into Nb 3 Al compound is a superconducting compound by a heat treatment to be described later, it may also indicate itself superconductivity before the transformation. Therefore, in the present specification, the term "Nb-Al-based superconducting wire" is used instead of "Nb-Al-based superconducting wire" for convenience, but it does not mean that superconductivity is excluded. Further, the Nb-Al-based wire, since usually obtained by cooling in liquid Ga, but Ga residue is adhered on the surface, Nb 3 Al compound transformation prior to Nb-Al based superconductor of the present invention It is preferable that there is substantially no Ga residue between the surface of the Nb-Al-based wire and the Nb-Al-based wire and the Ni film or the Cu film. In order to prevent the Ga residue from being substantially present, it is effective to remove the Ga residue before the Ni film is formed, whereby the Ni film and thus the Cu film are more firmly attached to the surface of the Nb-Al-based wire. In close contact.
前記のＣｕ皮膜の厚さとしては、４０μｍ以上であることが好ましく、４０μｍ以上であると安定化材としての機能をより確実に発揮することができる。Ｃｕ皮膜の厚さの上限としては特に限定されないが、超伝導線材全体に占める超伝導物質の割合を考慮すれば、通常は超伝導線材の線径（Ｃｕ皮膜を含む超伝導線材全体の直径）に対して６０％以下程度にとどめるのが好ましい。 The thickness of the Cu coating is preferably 40 μm or more, and when it is 40 μm or more, the function as a stabilizer can be more reliably exhibited. The upper limit of the thickness of the Cu coating is not particularly limited, but usually the wire diameter of the superconducting wire (the diameter of the entire superconducting wire including the Cu coating) in view of the ratio of the superconducting substance to the entire superconducting wire. However, it is preferable to keep it to about 60% or less.
本発明のＮｂ−Ａｌ系超伝導線材の線径としては、０．１ｍｍ以上が好ましい。０．１ｍｍ以上のものであれば、歩留まり良く製造できる。線径の上限としては特に限定されないが、可撓性等を考慮すれば３．０ｍｍ程度以下にとどめるのが好ましい。 The wire diameter of the Nb-Al superconducting wire of the present invention is preferably 0.1 mm or more. If it is 0.1 mm or more, it can be manufactured with high yield. The upper limit of the wire diameter is not particularly limited, but it is preferably about 3.0 mm or less in consideration of flexibility and the like.
本発明のＮｂ−Ａｌ系超伝導線材において重要なことは、前記Ｃｕ皮膜とＮｂ−Ａｌ系線材との間にＮｉ皮膜が介在することであり、このことによって安定化材としての銅皮膜が、種々の加工によっても耐えうるほど強固に密着して形成されるのである。そのような観点から、該Ｎｉ皮膜の厚さとしては、０．０１μｍ〜１０μｍであることが好ましい。０．０１μｍ未満では、Ｎｉ皮膜を設けた効果が十分に発揮されない場合があり、一方、１０μｍを超えると、ＮｉがＣｕ皮膜内に拡散して、Ｃｕの純度を低下させたり、外力により拡散層に割れが生じ易くなるという害をもたらす場合があるので、０．０１μｍ〜１０μｍであることが好ましいのである。 What is important in the Nb-Al-based superconducting wire of the present invention is that the Ni coating is present between the Cu coating and the Nb-Al-based wire, and thus the copper coating as the stabilizer is It is formed so as to be firmly adhered to withstand various processes. From such a viewpoint, the thickness of the Ni coating is preferably 0.01 μm to 10 μm. If it is less than 0.01 μm, the effect of providing the Ni coating may not be sufficiently exerted, while if it exceeds 10 μm, Ni diffuses into the Cu coating and reduces the purity of Cu, or a diffusion layer is formed by an external force. Therefore, it is preferable that the thickness is 0.01 μm to 10 μm, because it may cause the damage that cracks easily occur.
なお、前記のＮｉ皮膜およびＣｕ皮膜としては、いずれも電気めっきにより形成された皮膜、すなわち電気めっき皮膜であることが好ましい。所望の厚さの皮膜を簡便かつ経済的に形成でき、皮膜の均一性にも優れているからである。 The Ni coating and the Cu coating are preferably coatings formed by electroplating, that is, electroplating coatings. This is because a film having a desired thickness can be easily and economically formed and the film is excellent in uniformity.
本発明のＮｂ−Ａｌ系超伝導線材におけるＣｕ皮膜の密着性としては、ＪＩＳ−Ｈ−８５０４に準拠して、線材を片側に９０°曲げて元に戻し、さらに反対側に９０°曲げて元に戻すという作業を一往復とし、繰り返し曲げるという９０°曲げ試験を行った際に、４往復繰り返しても皮膜の剥離が認めらないことが好ましく、５往復繰り返しても皮膜の剥離が認めらないことがより好ましい。さらにいえば、線材が破断するまで皮膜の剥離の認められないことが特に好ましい。 As the adhesion of the Cu coating in the Nb-Al-based superconducting wire of the present invention, according to JIS-H-8504, the wire is bent 90° to one side and returned to its original position, and further bent to 90° to the other side. When performing a 90° bending test in which the work of returning to 1 cycle is repeated and repeatedly bent, it is preferable that peeling of the film is not recognized even after repeating 4 times, and peeling of the film is not recognized even after repeating 5 times. Is more preferable. Furthermore, it is particularly preferable that the film is not peeled off until the wire is broken.
次に、本発明の製造方法について説明する。
本発明のＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材の製造方法は、液体Ｇａ中で冷却して得られる過飽和固溶体の状態にあるＮｂ−Ａｌ系線材から、Ｎｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材を製造する方法であって、
（ａ）前記Ｎｂ−Ａｌ系線材の表面に付着したＧａ残滓を除去する工程；
（ｂ）工程（ａ）で得られる、表面のＧａ残滓が除去されたＮｂ−Ａｌ系線材を、該Ｎｂ−Ａｌ系線材を不動態化させない条件下で脱脂処理し、ついで酸洗浄処理する工程；
（ｃ）工程（ｂ）で得られる、酸洗浄処理されたＮｂ−Ａｌ系線材の表面を、ニッケルストライク浴を用いて、Ｎｉで電気めっきする工程；
（ｄ）工程（ｃ）で得られる、Ｎｉで電気めっきされたＮｂ−Ａｌ系線材の表面を、Ｃｕで電気めっきする工程
を含むことを特徴とする。
また、所望により、前記（ａ）〜（ｄ）の工程に加えて、
（ｅ）工程（ｄ）で得られる、Ｃｕで電気めっきされたＮｂ−Ａｌ系超伝導線材を、酸化防止雰囲気下４００〜７００℃でベーキングする工程
を含むことが好ましい。Next, the manufacturing method of the present invention will be described.
Nb 3 Al compound transformation method for manufacturing a previous Nb-Al-based superconducting wire of the present invention, the Nb-Al-based wire in a supersaturated solid solution obtained by cooling in liquid Ga, Nb 3 Al compound transformation before A method of manufacturing a Nb-Al-based superconducting wire according to
(A) a step of removing Ga residue attached to the surface of the Nb-Al-based wire rod;
(B) A step of degreasing the Nb-Al-based wire rod from which Ga residues on the surface have been removed obtained in step (a) under conditions that do not passivate the Nb-Al-based wire rod, and then subject to acid cleaning treatment. ;
(C) A step of electroplating the surface of the acid-cleaned Nb-Al-based wire obtained in step (b) with Ni using a nickel strike bath;
(D) A step of electroplating with Cu the surface of the Nb-Al-based wire rod electroplated with Ni obtained in step (c).
If desired, in addition to the steps (a) to (d),
(E) It is preferable to include a step of baking the Cu-electroplated Nb-Al-based superconducting wire obtained in step (d) at 400 to 700° C. in an antioxidant atmosphere.
本発明の製造方法で使用される過飽和固溶体の状態にあるＮｂ−Ａｌ系線材は、液体Ｇａ中で冷却して得られる線材であり、Ｇａ残滓が表面に付着している。前記の過飽和固溶体の状態にあるＮｂ−Ａｌ系超伝導線材は、ＮｂＡｌ／Ｎｂ複合線材を急熱し、その後直ちに液体Ｇａ中で急冷することにより得られる。急熱急冷手段としては、例えば、図３に示される急熱急冷装置を用いる公知の急熱急冷手段などが挙げられる。以下、図３を用いて、前記の過飽和固溶体の状態にあるＮｂ−Ａｌ系線材を得るための好ましい方法につき説明する。
図３に示される急熱急冷装置は、送出しリール３、通電キャプスタン１、液体Ｇａ浴（以下、Ｇａバスともいう）２、および巻取りリール４を具備する急熱急冷装置である。送出しリール３から送出したＮｂＡｌ／Ｎｂ複合線材を通電キャプスタン１とＧａバス２間で通電加熱して線材温度を２０００℃近くまで昇温させ、その後直ちに４０〜５０℃程度のＧａバス２で急冷して、過飽和固溶体の状態にあるＮｂ−Ａｌ系線材を生成させ、これを巻取りリール４に巻き取る。The Nb-Al-based wire rod in a supersaturated solid solution state used in the production method of the present invention is a wire rod obtained by cooling in liquid Ga, and Ga residue is attached to the surface. The Nb-Al-based superconducting wire in the supersaturated solid solution state is obtained by rapidly heating the NbAl/Nb composite wire and then immediately cooling it in the liquid Ga. Examples of the rapid heating/quenching means include known rapid heating/quenching means using the rapid heating/quenching device shown in FIG. Hereinafter, with reference to FIG. 3, a preferable method for obtaining the Nb-Al-based wire rod in the state of the above supersaturated solid solution will be described.
The rapid heating and quenching device shown in FIG. 3 is a rapid heating and quenching device including a delivery reel 3, an energization capstan 1, a liquid Ga bath (hereinafter, also referred to as Ga bath) 2, and a take-up reel 4. The NbAl/Nb composite wire sent out from the delivery reel 3 is electrically heated between the energization capstan 1 and the Ga bus 2 to raise the temperature of the wire to near 2000° C., and immediately thereafter, in the Ga bath 2 of about 40 to 50° C. It is rapidly cooled to produce an Nb-Al-based wire rod in the state of a supersaturated solid solution, which is wound on the winding reel 4.
前記ＮｂＡｌ／Ｎｂ複合線材は、公知であり、ジェリー・ロール（ＪＲ）法、ロッド・イン・チューブ（ＲＩＴ）法、クラッド・チップ・エクストルージョン（ＣＣＥ）法などにより製造される。
以下、図１および図２を用いて、ＪＲ法により製造されるＮｂＡｌ／Ｎｂ複合線材について説明する。The NbAl/Nb composite wire is known, and is manufactured by a jerry roll (JR) method, a rod-in-tube (RIT) method, a clad chip extrusion (CCE) method, or the like.
Hereinafter, the NbAl/Nb composite wire manufactured by the JR method will be described with reference to FIGS. 1 and 2.
図１は、ＮｂＡｌ／Ｎｂ複合線材の製造プロセスを表したフローチャートである。図２は、シングルビレット（ａ）、マルチビレット（ｂ）およびＮｂＡｌ／Ｎｂ複合線材（ｃ）の模式図である。
Ｎｂ棒（Ｎｂコア）にＡｌシートとＮｂシートとを重ね巻き（ＪＲ）して、フィラメントの母材となるシングルビレット（ａ）を作製する。このシングルビレット（ａ）に静水圧押出を施した後、伸線によりマルチビレット組込み用六角断面モノフィラメント線材を作製する。ついで、この六角断面モノフィラメント線材を多数本Ｎｂパイプに組込み、マルチビレット（ｂ）を作製する。マルチビレット（ｂ）に静水圧押出を施した後、伸線によりＮｂＡｌ／Ｎｂ複合線材（ｃ）を製造する。FIG. 1 is a flowchart showing a manufacturing process of a NbAl/Nb composite wire. FIG. 2 is a schematic view of a single billet (a), a multi billet (b) and a NbAl/Nb composite wire (c).
An Al sheet and an Nb sheet are lapped (JR) on an Nb rod (Nb core) to produce a single billet (a) which is a base material of a filament. After hydrostatically extruding this single billet (a), a hexagonal cross-section monofilament wire for incorporating a multi-billet is produced by wire drawing. Next, a multi-billet (b) is manufactured by incorporating a large number of this hexagonal cross-section monofilament wire into an Nb pipe. After the hydrostatic extrusion is applied to the multi-billet (b), the NbAl/Nb composite wire (c) is manufactured by wire drawing.
本発明の製造方法においては、前記した方法などによって得られた過飽和固溶体の状態にあるＮｂ−Ａｌ系線材に、以下の工程で示す処理が施されてゆく。以下、本発明の各工程につき説明する。
（工程ａ）
工程（ａ）は、前記の過飽和固溶体の状態にあるＮｂ−Ａｌ系線材の表面に付着したＧａ残滓を物理的に除去する工程である。Ｇａ残滓を除去する手段としては、物理的な手段が好ましく、例えば、研磨手段などが挙げられ、より具体的には、例えば、研磨紙で研磨する手段などが挙げられる。また、このような研磨手段は、摩擦熱を抑制するという点で、湿式で行われるのが好ましい。なお、Ｇａ残滓の除去は次工程（ｂ）の直前に行われればよく、物理的手段で除去する場合には、それに先立って、化学的な手段による除去を行っても差支えない。In the manufacturing method of the present invention, the Nb-Al-based wire rod in the state of the supersaturated solid solution obtained by the above-mentioned method or the like is subjected to the treatment shown in the following steps. Hereinafter, each step of the present invention will be described.
(Process a)
The step (a) is a step of physically removing the Ga residue attached to the surface of the Nb-Al-based wire in the state of the supersaturated solid solution. As a means for removing the Ga residue, a physical means is preferable, and for example, a polishing means and the like can be mentioned, and more specifically, a means for polishing with polishing paper and the like can be mentioned. Further, such a polishing means is preferably performed by a wet method from the viewpoint of suppressing frictional heat. The Ga residue may be removed just before the next step (b), and when it is removed by a physical means, it may be removed by a chemical means prior to the removal.
（工程ｂ）
工程（ｂ）は、工程（ａ）で得られる、表面のＧａ残滓が除去されたＮｂ−Ａｌ系線材を、該Ｎｂ−Ａｌ系線材を不動態化させない条件下で脱脂処理し、ついで酸洗浄処理する工程である。
（脱脂処理）
前記脱脂処理は、Ｎｂ−Ａｌ系線材を不動態化させない条件下で行われるが、この「Ｎｂ−Ａｌ系線材を不動態化させない条件」とは、Ｎｂ−Ａｌ系線材の表面を実質的に酸化させない条件を広く意味する。そのため、本発明の効果が大きく損なわれない範囲においてはＮｂ−Ａｌ系線材の表面が一部酸化していてもよい。
脱脂手段としては、本発明の目的を阻害しない限り特に限定されず、浸漬脱脂や陰極電解脱脂などの公知の脱脂手段が挙げられる。前記浸漬脱脂に用いる薬剤は公知のものでよく、市販されているいずれのメーカーのものでもよい。メーカー品を用いる場合には、メーカー推奨条件をそのまま適用しても支障がない。
前記陰極電解脱脂に用いる薬剤は公知のものでよく、市販のものであってよいが、好ましくは、商品名パクナエレクターＺ−１（カルボン酸塩、炭酸塩およびアミン類の混合物、ユケン工業株式会社製）と水酸化ナトリウムの組み合わせ、ないしは公知の水酸化ナトリウムと炭酸ナトリウムとの混合物である。好適な商品名パクナエレクターＺ−１と水酸化ナトリウムの組み合わせの陰極電解脱脂処理条件としては、下記表１に示される陰極電解脱脂処理条件が挙げられる。(Process b)
In the step (b), the Nb-Al-based wire rod obtained by removing the Ga residue on the surface obtained in the step (a) is subjected to a degreasing treatment under a condition that does not passivate the Nb-Al-based wire rod, and then acid cleaning. This is a processing step.
(Degreasing treatment)
The degreasing treatment is performed under the condition that the Nb-Al-based wire is not passivated. The "condition that the Nb-Al-based wire is not passivated" means that the surface of the Nb-Al-based wire is substantially It broadly means the condition of not oxidizing. Therefore, the surface of the Nb-Al-based wire may be partially oxidized as long as the effect of the present invention is not significantly impaired.
The degreasing means is not particularly limited as long as the object of the present invention is not impaired, and known degreasing means such as immersion degreasing and cathodic electrolytic degreasing can be mentioned. The chemical used for the above-mentioned immersion degreasing may be a known one, and may be any commercially available manufacturer. When using a manufacturer's product, the manufacturer's recommended conditions can be applied without any problem.
The chemicals used for the cathodic electrolytic degreasing may be known ones and may be commercially available ones, but preferably trade name Pacna Electa Z-1 (mixture of carboxylate, carbonate and amines, Yuken Industrial Co., Ltd. (Made by the company) and sodium hydroxide, or a known mixture of sodium hydroxide and sodium carbonate. Examples of suitable cathodic electrolytic degreasing treatment conditions for the combination of trade name Pakuna Elector Z-1 and sodium hydroxide include the cathodic electrolytic degreasing treatment conditions shown in Table 1 below.
また、好適な水酸化ナトリウムと炭酸ナトリウムとの混合物の陰極電解脱脂処理条件としては、下記表２に示される陰極電解脱脂処理条件が挙げられる。 In addition, as a preferable condition for cathodic electrolytic degreasing treatment of a mixture of sodium hydroxide and sodium carbonate, there can be mentioned the condition for cathodic electrolytic degreasing treatment shown in Table 2 below.
（酸洗浄処理）
前記酸洗浄処理は、本発明の目的を阻害しない限り特に限定されず、公知の酸洗浄処理であってもよいが、好ましくは浸漬による酸処理または陰極電解による酸処理である。例えば、前記酸洗浄処理として、フッ化水素酸を用いる酸浸漬処理を採用する場合には、好ましい酸浸漬処理条件は、４６％フッ化水素酸５０〜３００ｍＬ／Ｌ、温度２０〜３０℃および浸漬時間１〜１０分間である。
硫酸とフッ化水素酸との混液を用いる陰極電解による酸処理を採用する場合には、好ましい酸処理条件は、下記表３に示される条件である。(Acid cleaning treatment)
The acid cleaning treatment is not particularly limited as long as it does not impair the object of the present invention, and may be a known acid cleaning treatment, but preferably an acid treatment by immersion or an acid treatment by cathodic electrolysis. For example, when adopting an acid immersion treatment using hydrofluoric acid as the acid cleaning treatment, preferable acid immersion treatment conditions are 46% hydrofluoric acid 50 to 300 mL/L, temperature 20 to 30° C. and immersion. The time is 1 to 10 minutes.
When the acid treatment by cathodic electrolysis using a mixed solution of sulfuric acid and hydrofluoric acid is adopted, preferable acid treatment conditions are shown in Table 3 below.
また、硫酸とフッ化アンモニウムまたはフッ化ナトリウムとの混液を用いる陰極電解による酸処理を採用する場合には、好ましい酸処理条件は、下記表４に示される条件である。 When acid treatment by cathodic electrolysis using a mixed solution of sulfuric acid and ammonium fluoride or sodium fluoride is adopted, preferable acid treatment conditions are shown in Table 4 below.
（工程ｃ）
工程（ｃ）は、工程（ｂ）で得られる、酸洗浄処理されたＮｂ−Ａｌ系線材の表面を、ニッケルストライク浴を用いて、Ｎｉで電気めっきする工程である。(Process c)
The step (c) is a step of electroplating the surface of the Nb-Al-based wire, which has been subjected to the acid cleaning treatment, obtained in the step (b), with Ni using a nickel strike bath.
（ニッケルストライク浴）
前記ニッケルストライク浴は、本発明の目的を阻害しない限り特に限定されず、公知のニッケルストライク浴であってよいが、好ましくは、ニッケルの塩化物、硫酸塩およびスルファミン酸塩からなる群から選ばれる１種または２種以上のニッケル塩と、塩酸、硫酸またはスルファミン酸とを含んでなるｐＨ２以下の液であり、より好ましくは、ニッケルの析出と水素還元とを同時に起こせる低効率で多量の水素を発生する塩化物、硫酸塩およびスルファミン酸塩からなる群から選ばれる１種または２種以上のニッケル塩と、塩酸、硫酸またはスルファミン酸塩とを含んでなるｐＨ２以下の液である。このような好ましいニッケルストライク浴としては、より具体的には例えば、塩化物型（ウッド）ニッケルストライク浴、硫酸塩型ニッケルストライク浴、スルファミン酸型ニッケルストライク浴などが挙げられる。(Nickel strike bath)
The nickel strike bath is not particularly limited as long as it does not impair the object of the present invention, and may be a known nickel strike bath, but is preferably selected from the group consisting of nickel chloride, sulfate and sulfamate. A solution having a pH of 2 or less containing one or more nickel salts and hydrochloric acid, sulfuric acid or sulfamic acid, and more preferably a low-efficiency and large amount of hydrogen capable of simultaneously causing nickel precipitation and hydrogen reduction. A liquid having a pH of 2 or less, which contains one or more nickel salts selected from the group consisting of the generated chloride, sulfate and sulfamate, and hydrochloric acid, sulfuric acid or sulfamate. Specific examples of such a preferable nickel strike bath include a chloride type (wood) nickel strike bath, a sulfate type nickel strike bath, and a sulfamic acid type nickel strike bath.
前記塩化物型（ウッド）ストライク浴の好ましい浴組成としては、下記表５で示される浴組成が挙げられる。
前記硫酸塩型ニッケルストライク浴の好ましい浴組成としては、下記表６で示される浴組成が挙げられる。
前記スルファミン酸型ニッケルストライク浴の好ましい浴組成としては、下記表７で示される浴組成が挙げられる。
（工程ｄ）
工程（ｄ）は、工程（ｃ）で得られる、Ｎｉで電気めっきされたＮｂ−Ａｌ系線材の表面を、Ｃｕで電気めっきする工程である。(Process d)
Step (d) is a step of electroplating the surface of the Ni-electroplated Nb-Al-based wire rod obtained in step (c) with Cu.
（Ｃｕめっき浴）
工程（ｄ）において用いられるＣｕめっき浴は、本発明の目的を阻害しない限り特に限定されず、公知のＣｕめっき浴であってよい。しかしながら、銅の純度や伸びを必要とするために極力添加剤を含まないものや毒性が少なく、排水処理のやりやすい浴が好ましい。そのため、ホウフッ化銅浴やシアン化銅浴は避ける方がよく、硫酸銅浴やピロリン酸銅浴が好ましく採用されるが、ピロリン酸銅浴は適正なめっき条件が５０〜６０℃であるため、加熱を要するという難点があり、硫酸銅浴が最も好ましい。硫酸銅浴の好ましい条件は下記表８に示すとおりである。なお、線材のさらなる伸びの特性を要すれば通常の整流電源に替えて、パルス電源ないしＰＲ電源を利用してもよい。
The Cu plating bath used in the step (d) is not particularly limited as long as it does not impair the object of the present invention, and may be a known Cu plating bath. However, it is preferable to use a bath that does not contain additives as much as possible because it requires the purity and elongation of copper, has little toxicity, and is easy to treat wastewater. Therefore, it is better to avoid a copper borofluoride bath or a copper cyanide bath, and a copper sulfate bath or a copper pyrophosphate bath is preferably adopted. However, since the copper pyrophosphate bath has an appropriate plating condition of 50 to 60°C, A copper sulfate bath is the most preferable because it requires heating. The preferable conditions of the copper sulfate bath are as shown in Table 8 below. In addition, if a further expansion characteristic of the wire is required, a pulse power source or a PR power source may be used instead of the normal rectifying power source.
なお、本工程において電気めっきは、Ｃｕの皮膜の厚さが４０μｍ以上、より好ましくは１００μｍ以上、最も好ましくは１５０μｍ以上になるようにして行われるのが好ましい。また、工程（ｄ）で得られる、Ｃｕで電気めっきされたＮｂ−Ａｌ系超伝導線材（Ｎｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材）の線径は、特に限定されないが、０．１ｍｍ以上であるのが好ましく、０．５ｍｍ以上であるのがより好ましい。In this step, electroplating is preferably performed so that the thickness of the Cu film is 40 μm or more, more preferably 100 μm or more, and most preferably 150 μm or more. Further, obtained in step (d), the wire diameter of the electroplated Nb-Al-based superconducting wire (Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire) with Cu is not particularly limited, 0 It is preferably at least 1 mm, more preferably at least 0.5 mm.
（工程ｅ）
（工程ｅ）
工程（ｅ）は、工程（ｄ）で得られる、Ｃｕで電気めっきされたＮｂ−Ａｌ系線材を、酸化防止雰囲気下４００〜７００℃でベーキングする工程である。本工程により、Ｎｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線線材におけるＮｂ−Ａｌ系線材とＮｉないしＣｕ皮膜との密着性をより向上させることができるので、前記（ａ）〜（ｄ）の工程に加えて実施されることが好ましい。そのため、本工程では、Ｎｂ−Ａｌ系超伝導線材のＮｂ−Ａｌ成分をＮｂ３Ａｌ化合物に変態させないように、４００℃以上７００℃未満でベーキングが行われる。前記ベーキングは、好ましくは酸化防止雰囲気下４００〜６５０℃で、特に好ましくは酸化防止雰囲気下５００〜６５０℃で行われる。前記酸化防止雰囲気は、好ましくは、真空または不活性ガス雰囲気である。なお、本工程のベーキングによる線径の変化は通常殆ど認められない。(Process e)
(Process e)
Step (e) is a step of baking the Cu-electroplated Nb-Al-based wire obtained in step (d) at 400 to 700° C. in an antioxidant atmosphere. By this step, it is possible to further improve the adhesion between the Cu film to no Ni and Nb-Al-based wire in Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire, the (a) ~ (d It is preferable that it is performed in addition to the step (1). Therefore, in this step, baking is performed at 400°C or higher and lower than 700°C so as not to transform the Nb-Al component of the Nb-Al-based superconducting wire into the Nb 3 Al compound. The baking is preferably performed at 400 to 650° C. in an antioxidant atmosphere, and particularly preferably at 500 to 650° C. in an antioxidant atmosphere. The antioxidant atmosphere is preferably a vacuum or an inert gas atmosphere. Note that almost no change in wire diameter due to baking in this step is observed.
以上のようにして、Ｎｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線線材が得られる。本発明では、このＮｂ−Ａｌ系超伝導線線材をさらに熱処理して、Ｎｂ−Ａｌ系超伝導線線材中の過飽和固溶体の状態にあるＮｂ−Ａｌ系線材を構成する物質の少なくとも一部をＮｂ３Ａｌ化合物に変態させることにより、Ｎｂ３Ａｌ化合物系超伝導線材を製造することができる。すなわち、本発明のＮｂ３Ａｌ化合物系超伝導線材の製造方法は、前記の（ａ）〜（ｅ）の工程に加え、下記の工程（ｆ）を含むことを特徴とする。 As described above, Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire is obtained. In the present invention, the Nb-Al-based superconducting wire is further heat-treated so that at least a part of the substance forming the Nb-Al-based wire in the supersaturated solid solution state in the Nb-Al-based superconducting wire is Nb. A Nb 3 Al compound-based superconducting wire can be manufactured by transforming into a 3 Al compound. That is, the method for producing a Nb 3 Al compound-based superconducting wire according to the present invention is characterized by including the following step (f) in addition to the above steps (a) to (e).
工程（ｅ）で得られる、ベーキングされたＮｂ−Ａｌ系超伝導線材は、所望により成形加工されて、工程（ｆ）に用いられる。かかる成形は常法に従い行われ、成形手段としては、例えば、伸線などの公知の成形手段が挙げられる。前記成形により得られたＮｂ−Ａｌ系超伝導線材も、「工程（ｅ）で得られる、ベーキングされたＮｂ−Ａｌ系超伝導線材」として工程（ｆ）に用いることができる。 The baked Nb-Al-based superconducting wire obtained in the step (e) is optionally shaped and used in the step (f). Such molding is performed according to a conventional method, and examples of the molding means include known molding means such as wire drawing. The Nb-Al-based superconducting wire obtained by the molding can also be used in the step (f) as the "baked Nb-Al-based superconducting wire obtained in the step (e)".
（工程ｆ）
工程（ｆ）は、工程（ｅ）で得られる、ベーキングされたＮｂ−Ａｌ系超伝導線材を、７００℃以上の温度で熱処理する工程である。本工程により、Ｎｂ−Ａｌ系超伝導線材のＮｂ−Ａｌ成分をＮｂ３Ａｌ化合物に変態させることができる。本工程における熱処理温度は、Ｎｂ３Ａｌ化合物への変態が可能であり、かつ銅の熔融温度より低い温度であればよく、通常７００℃〜１０００℃であり、好ましくは７００℃を超え１０００℃以下の範囲内の温度である。(Process f)
Step (f) is a step of heat-treating the baked Nb-Al-based superconducting wire obtained in step (e) at a temperature of 700°C or higher. By this step, it is possible to transform the Nb-Al component of Nb-Al-based superconducting material Nb 3 Al compound. The heat treatment temperature in this step may be a temperature that allows transformation into an Nb 3 Al compound and is lower than the melting temperature of copper, and is usually 700° C. to 1000° C., preferably more than 700° C. and 1000° C. or less. The temperature is within the range.
かくして得られたＮｂ３Ａｌ化合物系超伝導線材は、核融合炉用マグネット、加速器用マグネット、高分解能を有する核磁気共鳴（ＮＭＲ）用マグネットなどに用いられる。The Nb 3 Al compound-based superconducting wire thus obtained is used for a nuclear fusion reactor magnet, an accelerator magnet, a nuclear magnetic resonance (NMR) magnet having high resolution, and the like.
以下に実施例を示して、本発明を具体的に説明するが、本発明はそれらの実施例に限定されないことはいうまでもない。
なお、実施例を示す前に、本発明を完成する過程で行った試験についての実験例を示す。
（実験例１）Ｎｂ基材に銅安定化材を強固に付着させる手法の発見に関する試験
試験片として、全て２．５ｍｍ厚の純Ｎｂ板を幅１０ｍｍ、長さ５０ｍｍに切断したものを利用した。また銅安定化材を被覆するめっき液として硫酸銅浴に暫定固定し、膜厚も０．１ｍｍ厚の銅めっきに固定して、めっき工程につきものの脱脂方法、不動態膜除去方法（活性化方法）、不動態化し易い金属や化学的置換を呈す金属に必須とされるストライクめっき（例えばステンレス鋼に必須とされるウッドニッケルストライクめっきや鉄材に直接銅めっきするためのシアン化銅めっきがそうである。）の有効性の有無さらには銅安定化材を被覆して後の熱処理の要否及び条件の妥当性を温度６００℃、１時間の加熱条件で確認することとした。
試験条件を下記表９に取りまとめた。なお、表９中の詳細な内容は次の通りである。Hereinafter, the present invention will be described specifically with reference to Examples, but it goes without saying that the present invention is not limited to these Examples.
In addition, before showing an Example, the experimental example about the test performed in the process of completing this invention is shown.
(Experimental Example 1) Test relating to discovery of a method for firmly attaching a copper stabilizing material to an Nb substrate As a test piece, a 2.5 mm thick pure Nb plate cut into a width of 10 mm and a length of 50 mm was used. .. Further, as a plating solution for coating the copper stabilizing material, it is temporarily fixed in a copper sulfate bath, and the film thickness is also fixed to a copper plating having a thickness of 0.1 mm. ), strike plating that is essential for metals that are easily passivated or that exhibits chemical substitution (for example, wood nickel strike plating that is essential for stainless steel, and copper cyanide plating for directly copper plating on iron materials). The presence or absence of the effectiveness of the above), the necessity of the subsequent heat treatment after coating the copper stabilizing material, and the validity of the conditions were confirmed under the heating conditions of a temperature of 600° C. for 1 hour.
The test conditions are summarized in Table 9 below. The detailed contents of Table 9 are as follows.
（１）各工程欄に記入してある「○」印は、当該工程を実行し、試したことを意味している。 (1) The mark "○" entered in each process column means that the process was executed and tried.
（２）「電解脱脂（＊１）」：水酸化ナトリウム ５０ｇ／Ｌ、炭酸ナトリウム ５０ｇ／Ｌの液で、温度５０℃に於いてＮｂ板を陽極にして電解する場合と陰極にして電解する場合とをそれぞれ陽極処理、陰極処理と表現している。なお適用電流密度は陽陰極共に５Ａ／ｄｍ２一定としている。(2) “Electrolytic degreasing (*1)”: a solution of sodium hydroxide 50 g/L and sodium carbonate 50 g/L, at a temperature of 50° C., using the Nb plate as the anode and electrolyzing as the cathode. And are described as anodizing and cathodic processing, respectively. The applied current density is constant at 5 A/dm 2 for both the positive and negative electrodes.
（３）酸洗・不動態膜除去工程の「電解処理（＊２）」とは、電解脱脂と同様にＮｂ板を陽陰極で処理する場合の区別をつけたものである。なお電解液は、Ｎｂを陽極にすると積極的に溶解（エッチング）する２０容量％硫酸とフッ化水素酸とを調合したものとしている。同じ酸洗い・不動態膜除去工程の「浸漬処理」には、無通電状態でも液に浸漬するだけでＮｂを溶解する硝酸とフッ化水素酸の混合液を用いた。なお硝酸は、Ｎｂの酸化剤として作用する。 (3) The “electrolytic treatment (*2)” in the pickling/passive film removing step is a distinction between the case where the Nb plate is treated with a positive cathode as in the case of electrolytic degreasing. The electrolytic solution is a mixture of 20% by volume sulfuric acid and hydrofluoric acid which are positively dissolved (etched) when Nb is used as an anode. In the same "immersion treatment" of the pickling/passive film removing step, a mixed solution of nitric acid and hydrofluoric acid was used, which dissolves Nb only by immersing in the solution even in a non-energized state. Nitric acid acts as an oxidizer for Nb.
（４）中間層被覆工程での「Ａ（＊３）」は、本発明で用いる塩化ニッケルと塩酸とからなり、通常ウッドニッケルストライクと称されるめっき前処理にのみ利用する。また「Ｂ（＊３）」は、硫酸ニッケルと硫酸とからなるストライクに利用するめっき液であり、いずれも付着速度重視ではなく、被めっき物の表面を水素還元しつつめっきを析出させる目的で利用する液である。なおいずれのストライク液も室温で５分間の固定条件でめっきした。 (4) "A(*3)" in the intermediate layer coating step is composed of nickel chloride and hydrochloric acid used in the present invention, and is used only for the pretreatment for plating which is usually called Wood Nickel Strike. Further, "B(*3)" is a plating solution used for a strike composed of nickel sulfate and sulfuric acid, neither of which attaches importance to the deposition rate and the purpose is to deposit the plating while hydrogen-reducing the surface of the object to be plated. It is the liquid to be used. Each strike solution was plated at room temperature for 5 minutes under fixed conditions.
（５）「Ｎｉ（＊４）」とは、代表的なニッケルめっき液であるワット浴を利用し、硫酸ニッケル２４０ｇ／Ｌ、塩化ニッケル４５ｇ／Ｌ、ホウ酸３５ｇ／Ｌとし、温度５０℃、電流密度２Ａ／ｄｍ２で５分間めっきした。(5) "Ni(*4)" is a typical nickel plating solution, a Watt bath is used, and nickel sulfate is 240 g/L, nickel chloride is 45 g/L, and boric acid is 35 g/L. Plating was performed at a current density of 2 A/dm 2 for 5 minutes.
（６）「銅（＊５）」は、Ｎｂが電位的に卑な金属であることを考慮し、鉄系材料に直接銅めっきする場合に多用するシアン化銅液を用い、銅ストライクとして５０℃に於いて、３Ａ／ｄｍ２、５分間めっきした。(6) "Copper (*5)" is a copper strike that uses a copper cyanide solution that is often used when directly copper-plating an iron-based material, considering that Nb is a base metal that is a potential. It was plated at 3 A/dm 2 for 5 minutes at ℃.
（７）「銀（＊６）」の場合も、Ｎｂが電位的に卑な金属である為に、化学置換防止のためにシアン化銀ストライク液を利用することとし、室温で１分間銀めっきした。 (7) In the case of "silver (*6)", since Nb is a base metal in terms of potential, a silver cyanide strike solution is used to prevent chemical substitution, and silver plating is performed for 1 minute at room temperature. did.
（結果）
前記で得られた各試験片（Ｎｏ．１〜Ｎｏ．１６）につき、９０°曲げ試験（前記した通り、ＪＩＳ−Ｈ−８５０４に準拠して行う。以下同じ。）を行った。結果を表１０に示す。
表１０中の銅安定化密着性評価欄の記号の説明
「◎」・・素材が破壊するまで（６往復繰り返すと破断）９０°曲げ試験を繰り返しても銅安定化材には剥離現象は全く認められない。
「○」・・９０°曲げ試験を３往復繰り返し、４往復目で始めて銅安定化材の剥離が見られる。
「△」・・９０°曲げ試験で１往復目では異常がなかったが２往復目で銅安定化材の剥離がみられる。
「×」・・９０°曲げ試験で１往復を終えるまでも耐えきれず９０°に曲げただけで銅安定化材の剥離が見られる。
「××」・・９０°曲げ試験に迄至らず、６００℃に加熱しただけで局所的に銅安定化材に膨れが発生する。
For each of the test pieces (No. 1 to No. 16) obtained above, a 90° bending test (as described above, performed according to JIS-H-8504, the same applies hereinafter) was performed. The results are shown in Table 10.
Explanation of symbols in the column for evaluating copper-stabilized adhesion in Table 10 "◎"... Until the material breaks (broken after repeating 6 reciprocations) Even if the 90° bending test is repeated, the copper-stabilized material has no peeling phenomenon. unacceptable.
"○" ··· The 90° bending test was repeated 3 times, and peeling of the copper stabilizer was observed after the 4th cycle.
"△" ··· In the 90° bending test, there was no abnormality in the first reciprocation, but peeling of the copper stabilizing material was observed in the second reciprocation.
“×” ···························· 90° bending test can not endure even after one reciprocation, and peeling of the copper stabilizing material can be seen only by bending at 90°.
"XX" --- The 90° bending test is not reached, and the copper stabilizer locally swells only by heating to 600°C.
前記結果より、脱脂工程では、それを電気的に行う電解脱脂とする場合にはＮｂへの水素吸蔵の危険を冒してでもＮｂ表面の酸化（不動態化）を回避するために陰極的に処理することが妥当であることを示唆している。また酸洗・不動態膜除去工程に於いても、それを浸漬処理で行う場合には硝酸の様な酸化剤を併用する溶液を用いるとＮｂの表面は速やかに溶解する。その反面溶解機構が硝酸による表面酸化とフッ化水素酸による酸化皮膜の溶解が繰り返される結果であろうが、常にＮｂ表面は酸化され不動態の状態となっているものと考えられる。従い、ニッケル中間層被覆までのいずれの工程であっても、一旦このような表面状態としてしまえば、以降の工程でニッケルストライクや銅安定化材被覆後の熱処理の効果は全く期待できないことを意味している。つまり手法を問わず、脱脂から中間層の形成までの全ての工程をＮｂへの水素吸蔵や表面に存在する加工変質層の除去の問題を度外視し、Ｎｂ表面を極力酸化、不動態化させないような工程でなければならないことを見出した。この知見からするとＮｂの電気めっきに関する公知の非特許文献２の手法が銅めっき皮膜の密着不良を呈すのは当然である。 From the above results, in the degreasing step, when electrolytic degreasing is performed electrically, the cathodic treatment is performed in order to avoid oxidation (passivation) of the Nb surface even at the risk of hydrogen storage in Nb. Suggest that it is reasonable to do so. Also in the pickling/passive film removing step, when it is carried out by dipping treatment, the surface of Nb is rapidly dissolved by using a solution which also uses an oxidizing agent such as nitric acid. On the other hand, the dissolution mechanism may be the result of repeated surface oxidation by nitric acid and dissolution of the oxide film by hydrofluoric acid, but it is considered that the Nb surface is always oxidized and in a passive state. Therefore, in any process up to the nickel intermediate layer coating, once such a surface state is set, the effect of heat treatment after nickel strike or copper stabilizing material coating cannot be expected at all in the subsequent steps. is doing. In other words, regardless of the method, the entire process from degreasing to formation of the intermediate layer is ignored for hydrogen storage in Nb and removal of the work-affected layer existing on the surface, and the surface of Nb should not be oxidized or passivated as much as possible. I found that it must be a different process. From this knowledge, it is natural that the known method of Non-Patent Document 2 regarding electroplating of Nb exhibits poor adhesion of the copper plating film.
さらに脱脂工程、酸洗・不動態膜除去工程の後の中間層被覆工程での適用皮膜種には明らかに適不適が存在し、電気めっき法に限定すれば特定の条件下に被覆したニッケルめっきが目的の達成に有利であることを見出した。特定の条件下に被覆したニッケルめっきとしては、積極的に皮膜の析出に利用する通常の液は当該目的には不適切で、めっきの前処理的に利用される強酸性、且つ低効率で多量の水素発生を伴いながら同時にニッケルの皮膜析出の起こる公知のストライク液種を利用することが効果的であった。その上で、銅安定化材形成後にはさらにベーキングするという条件を付与することが、安定化材とＮｂとをより強固に密着させる効果を奏し、課題の解決に大きく寄与することを見出した。なお、本試験に関連して知見したことをさらに補足すれば、脱脂工程で利用する浸漬脱脂剤や電解脱脂液は、市販のものが利用できる。しかし酸洗・不動態膜除去工程で利用する浸漬処理の薬剤としては硝酸の如き酸化剤を含まず、Ｎｂに対して反応するフッ化水素酸単独の浸漬処理や硫酸とフッ化水素酸の混液、硫酸とフッ化アンモニウムやフッ化ナトリウムからなる溶液中での陰極電解処理等が好ましい。またニッケル薄膜の被覆厚は、この試験で利用した条件では０．３〜０．８μｍの範囲となる。 Furthermore, there are obviously suitability and unsuitability for the applied film type in the intermediate layer coating process after the degreasing process and the pickling/passive film removal process, and nickel plating coated under specific conditions is limited to the electroplating method. Have been found to be advantageous for achieving the purpose. For nickel plating coated under specific conditions, the usual liquids that are actively used for film deposition are not suitable for this purpose, and are strongly acidic used as a pretreatment for plating, and have low efficiency and large amounts. It was effective to use a known strike liquid species in which nickel film deposition simultaneously occurs with the generation of hydrogen. Moreover, it has been found that giving a condition of further baking after forming the copper stabilizing material has an effect of more firmly adhering the stabilizing material and Nb, and contributes greatly to solving the problem. In addition, to supplement the findings of the present test, commercially available immersion degreasing agents and electrolytic degreasing solutions used in the degreasing step can be used. However, the dipping treatment chemicals used in the pickling/passive film removing step do not contain an oxidizing agent such as nitric acid, and dip treatment of hydrofluoric acid alone which reacts with Nb or a mixed solution of sulfuric acid and hydrofluoric acid. Cathodic electrolysis in a solution of sulfuric acid and ammonium fluoride or sodium fluoride is preferable. The coating thickness of the nickel thin film is in the range of 0.3 to 0.8 μm under the conditions used in this test.
（実験例２）銅安定化材をＮｂに密着させる為に好適な温度条件に関する試験
Ｎｂ表面に電気めっき技術で被覆した銅安定化材の強固な密着には最終的に熱処理（ベーキング）を行うことが極めて有効であることを知見したが、銅安定化材の熱処理による密着効果が脱水素にあるのかあるいはＮｂ及び銅安定化材への中間膜の同時拡散層形成にあるのかという問題がクリアになっていないと同時に、条件として好ましいベーキング温度範囲が未決定のままである。そこで本発明者等は、実験例１に利用したものと同じ純Ｎｂ板を用い、銅安定化材の被覆工程を表９のＮｏ．６の工程を利用して試料を作成し、アルゴン雰囲気炉を用いて、銅めっきのまま、３００℃、４００℃、５００℃、６００℃の各温度でベーキングした後、９０°曲げ試験により銅安定化材の密着性の評価を行った。結果を表１１に示す。(Experimental Example 2) Test on temperature conditions suitable for adhering copper stabilizer to Nb Final heat treatment (baking) is performed for firm adhesion of the copper stabilizer coated on the Nb surface by electroplating technique. Was found to be extremely effective, but the problem of whether the adhesion effect of the heat treatment of the copper stabilizer is due to dehydrogenation or the simultaneous diffusion layer formation of the intermediate film on Nb and the copper stabilizer is clear. At the same time, the preferable baking temperature range as a condition remains undecided. Therefore, the inventors of the present invention used the same pure Nb plate as that used in Experimental Example 1 and described the copper stabilizing material coating step in No. 9 of Table 9. A sample was prepared by using the process of No. 6, and after being baked at 300° C., 400° C., 500° C., and 600° C. in an argon atmosphere furnace, the copper was stable by the 90° bending test after baking at each temperature of 300° C., 400° C., 500° C., and 600° C. The adhesiveness of the chemical material was evaluated. The results are shown in Table 11.
表１１中、密着性の評価記号：
「◎」・・・素材のＮｂが破断（６往復繰り返し、７往復目に破断）してもＮｂからの銅安定化材の剥離は全く認められない。
「○」・・・３往復目までは異常がなかったが４往復目に銅安定化材の剥離が見られた。
「△」・・・１往復目までは異常がなかったが２往復目で銅安定化材の剥離が見られた。In Table 11, evaluation symbols for adhesion:
“A”: No peeling of the copper stabilizing material from Nb is observed even if Nb of the material breaks (repeats 6 times, breaks at 7th stroke).
“O”: No abnormality was observed up to the third round trip, but peeling of the copper stabilizing material was observed at the fourth round trip.
“A”: No abnormality was observed up to the first reciprocation, but peeling of the copper stabilizing material was observed at the second reciprocation.
表１１の結果は、３００℃迄のベーキング温度は実質的に銅安定化材の密着性改善には影響を及ぼさず、４００℃以上のベーキング温度で初めて密着性の改善効果が見られることを発見した。さらに結果から見るとベーキング時間の長短は余り関与していないということになる。ちなみにＥＰＭＡ（電子線マイクロアナライザー；島津製作所ＥＰＭＡ８７０５）により、それぞれの試料断面から特性Ｘ線像で確認すると４００℃では時間の長短に関わらずＮｂ及び銅へのニッケルの拡散の存在は、判別不能なレベルである。さらに５００℃を超えても依然としてＮｂ側へのニッケルの拡散は判別可能なレベルになく、殆どないといってもよい状態にある。しかし銅側に向かっては５００℃に於いて０．５μｍ程度、また６００℃では１〜２μｍ程度の拡散層の存在が確認されている。銅側への選択拡散は、銅とニッケルとの低い再結晶温度が関与していると思われ、それぞれ銅では２００℃、ニッケルでは４００〜６００℃とされ、両金属共に再結晶温度に到達していることが相互拡散を助長しているものと考えられる。その一方でニッケルのＮｂ側への拡散が殆ど皆無に近く、従って５００℃以上で極めて強固に銅安定化材がＮｂと密着する根拠とするに足る理由とはなり得ない。一方で脱水素の効果とするにしても通常レベルで実施する脱水素目的の温度域は１５０〜２５０℃であり、はるかに高い温度域に於いで密着性改善効果に繋がることを脱水素の効果であるとするのもいささか不自然である。いずれにしても銅安定化材のＮｂへの密着性確保手段として好ましいベーキング温度域は、４００℃以上であって、特に好ましい温度は５００℃以上である。また温度上限はＮｂ３Ａｌへの変態化を考慮すれば７００℃未満ということになるが、安全を見込めば６５０℃程度となる。なおベーキングには、たまたまアルゴンを利用する不活性雰囲気炉を用いたが、銅安定化材を密着させるという要件に対しては、これに制約を受けるものではない。つまり窒素雰囲気炉としてもまた真空炉としても特に支障はなく、銅安定化材の高温酸化という問題を無視すれば大気炉であっても支障がない。
これまでは主として純Ｎｂの板材でＮｂと銅安定化材との密着性を得る手法に限定していたが、実際の過飽和固溶体の状態にあるＮｂ−Ａｌ系線材では程度の差はあれ、急熱・急冷時に利用したＧａ残滓がその表面に存在しているのも事実である。そこでこの影響を明らかにするために実際に過飽和固溶体化させたＮｂ−Ａｌ系線材を利用して、Ｇａ残滓の除去とそれが銅安定化材の密着性に及ぼす影響とを試験して、本発明を完成することができた。そのようにして完成した発明の具体例についての結果を取りまとめて、以下の実施例１、比較例１、２に於いて説明する。The results shown in Table 11 indicate that the baking temperature up to 300°C does not substantially affect the improvement of the adhesion of the copper stabilizing material, and the effect of improving the adhesion can be seen only at the baking temperature of 400°C or higher. did. Furthermore, the results show that the length of baking time is not much involved. By the way, by using an EPMA (electron beam microanalyzer; EPMA8705 manufactured by Shimadzu Corp.) to confirm the characteristic X-ray image from each sample cross section, it is impossible to determine the presence of nickel diffusion into Nb and copper at 400°C regardless of the length of time. It is a level. Further, even if the temperature exceeds 500° C., the diffusion of nickel to the Nb side is not at a level that can be discriminated, and it can be said that there is almost no diffusion. However, the presence of a diffusion layer of about 0.5 μm at 500° C. toward the copper side and about 1 to 2 μm at 600° C. has been confirmed. It is thought that the low recrystallization temperature of copper and nickel is involved in the selective diffusion to the copper side, which is 200°C for copper and 400 to 600°C for nickel, respectively, and both metals reach the recrystallization temperature. It is considered that the promotion of mutual diffusion is promoted. On the other hand, there is almost no diffusion of nickel to the Nb side, and therefore it cannot be a sufficient reason for the copper stabilizer to firmly adhere to Nb at 500° C. or higher. On the other hand, even if the dehydrogenation effect is used, the temperature range for dehydrogenation performed at a normal level is 150 to 250°C, and the effect of dehydrogenation is that it leads to an adhesion improvement effect in a much higher temperature range. It is a little unnatural to say. In any case, a preferable baking temperature range as a means for ensuring the adhesion of the copper stabilizer to Nb is 400° C. or higher, and a particularly preferable temperature is 500° C. or higher. The upper limit of temperature is less than 700°C in consideration of transformation into Nb 3 Al, but it is about 650°C in view of safety. It should be noted that although an inert atmosphere furnace using argon happened to be used for baking, it is not limited to the requirement of closely adhering the copper stabilizing material. That is, there is no particular problem as a nitrogen atmosphere furnace or as a vacuum furnace, and as long as the problem of high temperature oxidation of the copper stabilizing material is ignored, there is no problem even if it is an atmospheric furnace.
Up to now, the method has been mainly limited to the method of obtaining the adhesion between Nb and the copper stabilizing material with a plate material of pure Nb, but with an actual Nb-Al-based wire rod in a supersaturated solid solution state, there is a degree of difference, It is also true that the Ga residue used during heating and quenching is present on the surface. Therefore, in order to clarify this effect, the Nb-Al-based wire rod that was actually made into a supersaturated solid solution was used to test the removal of Ga residue and its effect on the adhesion of the copper stabilizer, and I was able to complete the invention. The results of specific examples of the invention thus completed are summarized and described in Example 1 and Comparative Examples 1 and 2 below.
（実施例１）
本実施例では、液体Ｇａを冷却媒として用いる急熱急冷法により得られたＮｂ−Ａｌ系線材を用いた。なお、この線材は０．８ｍｍφ×４０ｍｍ長さである。線材を＃４００エメリー紙＋＃８００エメリー紙で表層４μｍ研磨除去した（工程ａ）。水洗後、脱脂剤として商品名パクナ１００ＭＡ３５ｇ／Ｌ（ユケン工業社製脱脂剤）を用いて、温度７０℃、５分の条件で浸漬脱脂し、ついで、９７％硫酸２００ｍＬ／Ｌおよび４６％フッ化水素酸５０ｍＬ／Ｌ、室温、陰極電流密度×時間：３Ａ／ｄｍ２×３分の条件で陰極電解による酸処理を行った（工程ｂ）。水洗後、塩化物型Ｎｉストライク（ウッド浴）を用いて、塩化ニッケル２４０ｇ／Ｌおよび３５％塩酸５０ｇ／Ｌ、室温、陰極電流密度×時間：３Ａ／ｄｍ２×３分の条件で電気めっきした（工程ｃ）。水洗後、硫酸銅浴を用いて、硫酸銅１６０ｇ／Ｌ、硫酸１２０ｇ／Ｌおよび塩素イオン２０ｍｇ／Ｌ、室温、陰極電流密度×時間：３Ａ／ｄｍ２×３時間のめっき条件で、めっき厚が０．１ｍｍとなるように電気めっきした（工程ｄ）。水洗後、アルゴン雰囲気炉、６００℃×１時間の条件でベーキングした。このようにして、Ｎｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材を得た。(Example 1)
In this example, an Nb-Al-based wire rod obtained by a rapid heating and quenching method using liquid Ga as a cooling medium was used. The wire rod had a length of 0.8 mmφ×40 mm. The wire was polished and removed with a surface layer of 4 μm using #400 emery paper+#800 emery paper (step a). After washing with water, 35 g/L of trade name Pakuna 100MA (a degreasing agent manufactured by Yuken Industry Co., Ltd.) was used as a degreasing agent, immersion degreasing was performed at a temperature of 70°C for 5 minutes, and then 97% sulfuric acid 200 mL/L and 46% fluorination Hydrochloric acid 50 mL/L, room temperature, cathode current density x time: Acid treatment by cathodic electrolysis was performed under the conditions of 3 A/dm 2 x 3 minutes (step b). After washing with water, electroplating was performed using a chloride type Ni strike (Wood bath) under the conditions of nickel chloride 240 g/L and 35% hydrochloric acid 50 g/L, room temperature, cathode current density×time: 3 A/dm 2 ×3 minutes. (Step c). After washing with water, using a copper sulfate bath, the plating thickness was 160 g/L of copper sulfate, 120 g/L of sulfuric acid and 20 mg/L of chloride ions, room temperature, and cathode current density×time: 3 A/dm 2 ×3 hours. It electroplated so that it might become 0.1 mm (process d). After washing with water, baking was performed in an argon atmosphere furnace at 600° C. for 1 hour. In this way, an Nb-Al-based superconducting wire before Nb 3 Al compound transformation was obtained.
（参考例１〜２）
Ｇａ残滓の除去工程（ａ）において、Ｇａ残滓の除去を試みる方法を、研磨処理に代えて、参考例１では、６３％硝酸２００ｍＬ／Ｌおよび４６％フッ化水素酸１００ｍＬ／Ｌ、室温、１０分の条件で浸漬処理を、参考例２では、９７％硫酸２００ｍＬ／Ｌおよび４６％フッ化水素酸５０ｍＬ／Ｌ、室温、陽極電流密度×時間：５Ａ／ｄｍ２×１０分の陽極電解処理を行ったこと、および参考例１〜２のいずれもが線材外径を基準に約８μｍ表層除去したこと以外は、実施例１と同じ操作をして参考例１〜２のＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材をそれぞれ製造した。(Reference Examples 1-2)
In the Ga residue removal step (a), the method of attempting to remove the Ga residue was replaced with polishing, and in Reference Example 1, 63% nitric acid 200 mL/L and 46% hydrofluoric acid 100 mL/L, room temperature, 10 Immersion treatment under the condition of min., in Reference Example 2, 97% sulfuric acid 200 mL/L and 46% hydrofluoric acid 50 mL/L, room temperature, anodic current density×time: 5 A/dm 2 ×10 minutes of anodic electrolysis treatment. Before the Nb 3 Al compound transformation of Reference Examples 1 and 2 was performed in the same manner as in Example 1 except that the surface layer was removed by about 8 μm based on the outer diameter of the wire rod in each of Reference Examples 1 and 2. Each of the Nb-Al superconducting wire rods of
なお、参考例において、線材表面からのＧａ残滓の除去にＮｂの溶解薬液を使用した理由は、ＥＰＭＡによる先の断面調査結果によって、Ｇａは単純に線材表面に付着しているのではなく、その一部はＮｂ表層から線材の中心に向かって約２μｍ程度の厚みを有するＮｂとＧａとの拡散層が存在するとの知見を得たことにある。 In the reference example, the reason why the Nb-dissolved chemical solution was used to remove the Ga residue from the surface of the wire was that the Ga was not simply attached to the surface of the wire according to the results of the previous cross-section investigation by EPMA. It is based on the knowledge that there is a diffusion layer of Nb and Ga having a thickness of about 2 μm from the surface layer of Nb toward the center of the wire.
実施例１および参考例１〜２で得られたＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材について、９０°曲げ試験により銅安定化材の密着性を評価した。結果を表１２に示す。For Examples 1 and Nb-Al system before the resulting Nb 3 Al compound metamorphosis in Reference Example 1-2 superconducting wire was evaluated the adhesion of the copper stabilizer by 90 ° bending test. The results are shown in Table 12.
下記表１２中の記号の説明；
「◎」・・素材のＮｂが破断しても銅安定化材の剥離は全く認められない。（６往復繰り返し、７往復目に破断）
「△」・・３往復繰り返し４往復目に銅安定化材の剥離が見られる。
「×」・・１往復目では異常がないが２往復目で銅安定化材の剥離が見られる。Explanation of symbols in Table 12 below;
“A”: No peeling of the copper stabilizer is observed even if the material Nb is broken. (Repeat 6 rounds, break at 7th round)
"△" ··· Repeated 3 reciprocations At 4th reciprocation, peeling of the copper stabilizer was observed.
“×” ··· No abnormality in the first reciprocation, but peeling of the copper stabilizing material is seen in the second reciprocation.
表１２の実施例１と参考例１〜２からも明らかな如く、銅安定化材を被覆する電気めっき工程は、基本的に表９のＮｏ．６と同一である。このことから勘案すると電気めっき以前に実施するＧａ残滓の除去に於いてもＮｂの酸化（不動態化）の影響が以後の工程にも全面的に影響するとの知見を得た。そしてまたこの影響は最後のベーキング工程でも解消されず銅安定化材の密着性に関与する。 As is clear from Example 1 and Reference Examples 1 and 2 in Table 12, the electroplating process for coating the copper stabilizing material is basically performed in No. Same as 6. Considering this, it was found that the influence of Nb oxidation (passivation) in the removal of the Ga residue, which is carried out before the electroplating, also affects the subsequent steps. Moreover, this effect is not eliminated even in the final baking step and contributes to the adhesion of the copper stabilizer.
（実施例２）
実施例１の工程ａと同じ操作をして、Ｇａ残滓を＃４００エメリー紙と＃８００エメリー紙とを用いて除去した後（工程ａの後）、水洗し、ついで陰極電解脱脂した。水洗後、１０容量％フッ化水素酸に室温、５分間浸漬し、ついで水洗し、実施例１の工程ｃと同じ操作をして、ニッケルストライクによる工程ｃを実施した。水洗後、実施例１で用いたのと同じ硫酸銅浴を用いて、２５℃、３Ａ／ｄｍ２の条件で、それぞれ５０μｍ、１００μｍ、１５０μｍ、２００μｍ、２５０μｍを目標に電気銅めっき皮膜を被覆して５種類の試料を作成した。それぞれに密着性を付与するために５００℃で１時間、真空炉中でベーキングした後、さらに８００℃で１０時間、Ｎｂ３Ａｌへの変態化目的で熱処理を行い、目標残留抵抗比（ＲＲＲ）を測定した。結果を表１３に示すが、銅安定化材に必要と見なされる目標残留抵抗比（ＲＲＲ）を１００以上とした場合には、これを満足する銅めっき安定化材の必要膜厚は、１００μｍ以上、より好ましくは１５０μｍであることが分かる。またＮｂと安定化材となる銅めっき皮膜の界面にニッケル薄膜が介在しても特性に影響しないことも明らかである。銅安定化材の密着力の程度を調査するために、５００℃で１時間ベーキングした１００μｍ目標の銅安定化材被覆線材試料をカセットローラーダイスにより伸線加工に供した。伸線前の線材径は、１．０５〜１．０２ｍｍであったが伸線後には、０．６６８〜０．６９７ｍｍと元の平均断面積の約４２％の平均断面積にまで伸線されたことになる。しかし前後の線材断面を光学顕微鏡観察してもＮｂと銅との界面には何ら異常は見られず、また銅めっき皮膜の割れなども一切見られない。参考までに伸線前後の断面ミクロ組織を図５に示す。(Example 2)
After performing the same operation as in step a of Example 1 to remove the Ga residue using #400 emery paper and #800 emery paper (after step a), it was washed with water and then subjected to cathodic electrolytic degreasing. After washing with water, it was immersed in 10% by volume hydrofluoric acid at room temperature for 5 minutes, followed by washing with water, and the same operation as step c of Example 1 was carried out to carry out step c by nickel strike. After washing with water, the same copper sulfate bath as that used in Example 1 was used to coat an electrolytic copper plating film with the targets of 50 μm, 100 μm, 150 μm, 200 μm, and 250 μm under the conditions of 25° C. and 3 A/dm 2. 5 kinds of samples were prepared. After being baked in a vacuum furnace at 500°C for 1 hour to give adhesion to each, further heat-treated at 800°C for 10 hours for the purpose of transformation into Nb 3 Al to obtain a target residual resistance ratio (RRR). Was measured. The results are shown in Table 13. When the target residual resistance ratio (RRR) considered necessary for the copper stabilizer is set to 100 or more, the required film thickness of the copper plating stabilizer satisfying this is 100 μm or more. It can be seen that, more preferably 150 μm. It is also clear that the characteristics will not be affected even if the nickel thin film is present at the interface between Nb and the copper plating film serving as the stabilizing material. In order to investigate the degree of adhesion of the copper stabilizer, a 100 μm target copper stabilizer coated wire rod sample baked at 500° C. for 1 hour was subjected to wire drawing with a cassette roller die. The wire diameter before wire drawing was 1.05 to 1.02 mm, but after wire drawing, the wire was drawn to an average cross sectional area of 0.668 to 0.697 mm, which was about 42% of the original average cross sectional area. It will be. However, no abnormalities are observed at the interface between Nb and copper, and no cracks in the copper plating film are observed even when the cross-sections of the front and rear wires are observed with an optical microscope. For reference, the cross-sectional microstructure before and after drawing is shown in FIG.
以上の如く、本発明は、Ｎｂ３Ａｌ化合物系超伝導線材が高い臨界温度（Ｔｃ）と上部臨界磁界（ＨＣ２）を示すことから、実用化が大いに望まれるＮｂ−Ａｌ系の超伝導線材に於いて、信頼するに足る密着力を有する安定化材を電気めっきという汎用性のある技術とベーキングとの組み合わせで具現化するもので、量産性と経済性に優れることはいうまでもない。これにより従来安定化材の被覆形成で行き詰まり状態にあったＮｂ−Ａｌ系線材の実用が可能となることで不可能であった強磁界用、交流用のＮｂ−Ａｌ系超伝導線材の製造が実現する。
そのため、本発明によって、核融合炉用マグネット、加速器用マグネット、高分解能を有する核磁気共鳴（ＮＭＲ）用マグネットに有用なＮｂ３Ａｌ化合物系超伝導線材を工業的有利に製造することができる。
As described above, according to the present invention, the Nb 3 Al compound-based superconducting wire exhibits a high critical temperature (Tc) and an upper critical magnetic field (H C2 ). In this case, it is needless to say that the stabilizing material having a reliable adhesion is realized by a combination of electroplating, which is a versatile technique, and baking, and is excellent in mass productivity and economical efficiency. As a result, it becomes possible to put into practical use Nb-Al-based wire rods that have been in a deadlocked state due to the coating of the stabilizing material, and it is impossible to manufacture Nb-Al-based superconducting wire rods for strong magnetic fields and AC. To be realized.
Therefore, according to the present invention, it is possible to industrially advantageously manufacture a Nb 3 Al compound-based superconducting wire useful for a nuclear fusion reactor magnet, an accelerator magnet, and a nuclear magnetic resonance (NMR) magnet having high resolution.
Claims (20)
（ａ）前記Ｎｂ−Ａｌ系線材の表面に付着したＧａ残滓を除去する工程；
（ｂ）工程（ａ）で得られる、表面のＧａ残滓が除去されたＮｂ−Ａｌ系線材を、該Ｎｂ−Ａｌ系線材を不動態化させない条件下で脱脂処理し、ついで酸洗浄処理する工程；
（ｃ）工程（ｂ）で得られる、酸洗浄処理されたＮｂ−Ａｌ系線材の表面を、ニッケルストライク浴を用いて、Ｎｉで電気めっきする工程；および
（ｄ）工程（ｃ）で得られる、Ｎｉで電気めっきされたＮｂ−Ａｌ系線材の表面を、Ｃｕで電気めっきする工程
を含むことを特徴とするＮｂ３Ａｌ化合物変態前のＮｂ−Ａｌ系超伝導線材の製造方法。From Nb-Al-based wire in a supersaturated solid solution obtained by cooling in liquid Ga, a method for producing a Nb 3 Al compound transformation prior to Nb-Al-based superconducting wire,
(A) a step of removing Ga residue attached to the surface of the Nb-Al-based wire rod;
(B) A step of degreasing the Nb-Al-based wire rod from which Ga residues on the surface have been removed obtained in step (a) under conditions that do not passivate the Nb-Al-based wire rod, and then subject to acid cleaning treatment. ;
(C) A step of electroplating the surface of the acid-cleaned Nb-Al-based wire obtained in step (b) with Ni using a nickel strike bath; and (d) obtained in step (c). , A method of manufacturing an Nb-Al-based superconducting wire before Nb 3 Al compound transformation, comprising a step of electroplating with Cu the surface of the Nb-Al-based wire material electroplated with Ni.
（ｅ）工程（ｄ）で得られる、Ｃｕで電気めっきされたＮｂ−Ａｌ系線材を、酸化防止雰囲気下４００℃以上７００℃未満でベーキングする工程
を含むことを特徴とする請求の範囲第６項に記載の製造方法。In addition to the steps (a) to (d),
7. The method according to claim 6, further comprising the step (e) of baking the Cu-electroplated Nb-Al-based wire obtained in step (d) at a temperature of 400° C. or higher and lower than 700° C. in an antioxidant atmosphere. The manufacturing method according to item.
（ａ）前記Ｎｂ−Ａｌ系超伝導線材の表面に付着したＧａ残滓を除去する工程；
（ｂ）工程（ａ）で得られる、表面のＧａ残滓が除去されたＮｂ−Ａｌ系線材を、該Ｎｂ−Ａｌ系線材を不動態化させない条件下で脱脂処理し、ついで酸洗浄処理する工程；
（ｃ）工程（ｂ）で得られる、酸洗浄処理されたＮｂ−Ａｌ系線材の表面を、ニッケルストライク浴を用いて、Ｎｉで電気めっきする工程；
（ｄ）工程（ｃ）で得られる、Ｎｉで電気めっきされたＮｂ−Ａｌ系線材の表面を、Ｃｕで電気めっきする工程；
（ｅ）工程（ｄ）で得られる、Ｃｕで電気めっきされたＮｂ−Ａｌ系線材を、酸化防止雰囲気下４００℃以上７００℃未満でベーキングする工程；および
（ｆ）工程（ｅ）で得られる、ベーキングされたＮｂ−Ａｌ系線材を、７００℃以上の温度で熱処理する工程
を含むことを特徴とするＮｂ３Ａｌ化合物系超伝導線材の製造方法。From Nb-Al-based wire in a supersaturated solid solution obtained by cooling in liquid Ga, a method for producing a Nb 3 Al compound-based superconducting wire,
(A) a step of removing Ga residue attached to the surface of the Nb-Al superconducting wire;
(B) A step of degreasing the Nb-Al-based wire rod from which Ga residues on the surface have been removed obtained in step (a) under conditions that do not passivate the Nb-Al-based wire rod, and then subject to acid cleaning treatment. ;
(C) A step of electroplating the surface of the acid-cleaned Nb-Al-based wire obtained in step (b) with Ni using a nickel strike bath;
(D) A step of electroplating the surface of the Ni-electroplated Nb-Al-based wire obtained in step (c) with Cu;
(E) a step of baking the Cu-electroplated Nb-Al-based wire obtained in step (d) at 400° C. or higher and lower than 700° C. in an antioxidation atmosphere; and (f) obtained in step (e) A method for producing a Nb 3 Al compound-based superconducting wire, comprising the step of heat-treating the baked Nb-Al-based wire at a temperature of 700° C. or higher.
The manufacturing method according to claim 14, wherein the heat treatment in the step (f) is performed at a temperature of 700°C to 1000°C.
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| PCT/JP2006/310386 WO2006129540A1 (en) | 2005-05-30 | 2006-05-24 | Nb-Al TYPE SUPERCONDUCTING WIRE HAVING STABILIZING COPPER DEPOSIT TENACIOUSLY ADHERENT THERETO AND PROCESS FOR PRODUCING THE SAME |
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