JP3574461B2 - Manufacturing method of oxide superconducting wire - Google Patents
Manufacturing method of oxide superconducting wire Download PDFInfo
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- JP3574461B2 JP3574461B2 JP13022193A JP13022193A JP3574461B2 JP 3574461 B2 JP3574461 B2 JP 3574461B2 JP 13022193 A JP13022193 A JP 13022193A JP 13022193 A JP13022193 A JP 13022193A JP 3574461 B2 JP3574461 B2 JP 3574461B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
Description
【０００１】
【産業上の利用分野】
この発明は、酸化物超電導線材の製造方法に関するものであり、特に、高い臨界電流密度を有する酸化物超電導線材の製造方法に関するものである。
【０００２】
【従来の技術】
近年、より高い臨界温度を示す超電導材料として、セラミック系のもの、すなわち、酸化物超電導材料が注目されている。その中で、イットリウム系は９０Ｋ、ビスマス系は１１０Ｋ、タリウム系は１２０Ｋ程度の高い臨界温度を示し、実用化が期待されている。
【０００３】
これらの酸化物超電導材料においては、粉末を熱処理した後金属シースにて被覆し、伸線加工および圧延加工を施した後、さらに熱処理することにより、高い臨界電流密度を有する単芯の酸化物超電導線材が得られている。また、酸化物超電導材料を主成分とする粉末を熱処理した後金属シースにて被覆し、伸線加工を施した後嵌合して多芯線とし、伸線加工および圧延加工を施した後、さらに熱処理することにより、同様に高い臨界電流密度を有する酸化物超電導多芯線材が得られている。さらに、従来、このような酸化物超電導線材の製造において、圧延加工および熱処理のステップを複数回繰り返すことにより、より高い臨界電流密度を有する酸化物超電導線材が得られることが知られている。
【０００４】
【発明が解決しようとする課題】
酸化物超電導線材をケーブルやマグネットに応用する際には、高い臨界温度に加えて、高い臨界電流密度を有していることが必要である。また、長い酸化物超電導線材においては、均一な特性を持つことも必要である。
【０００５】
前述した従来の方法により作製された単芯および多芯の酸化物超電導線材の臨界電流密度は、１０ｃｍ程度の短尺線材においては、３万Ａ／ｃｍ２ 以上の高い値が得られている。
【０００６】
しかしながら、長尺線材の製造においては、焼結のために行なわれる圧延後の熱処理の際に、線材が膨れてしまうという現象が生じる。短尺線材の場合には、焼結までの工程で原料粉末に吸着したガスは、熱処理の際線材の両端から抜けていくが、長尺線材の場合には、原料粉末に吸着したガスは、熱処理の際十分に抜けることがなく、線材内で膨張してしまうためである。そして、この線材の膨張により、線材の超電導特性が不均一となってしまうという問題があった。また、線材の膨張によって超電導体の組織が乱れるために、臨界電流密度が低下してしまうという問題もあった。
【０００７】
これらのことから、従来の方法で製造された長尺線材、たとえば、１００ｍ級の酸化物超電導線材の臨界電流密度は、１万Ａ／ｃｍ２ 程度の値しか得られなかった。
【０００８】
この発明の目的は、上述の問題点を解決し、高い臨界電流密度を有する長尺の酸化物超電導線材の製造方法を、提供することにある。
【０００９】
【課題を解決するための手段】
請求項１の発明によるビスマス系酸化物超電導線材の製造方法は、ビスマス系酸化物超電導材料を主成分とする粉末を熱処理した後金属シースにて被覆し、伸線加工および圧延加工を施した後、さらに熱処理する、ビスマス系酸化物超電導線材の製造方法であって、伸線加工の工程において、減圧雰囲気中５５０℃〜７６０℃の温度で熱処理を施すことを特徴としている。
【００１０】
請求項２の発明によるビスマス系酸化物超電導線材の製造方法は、ビスマス系酸化物超電導材料を主成分とする粉末を熱処理した後金属シースにて被覆し、伸線加工を施した後嵌合して多芯線とし、伸線加工および圧延加工を施した後、さらに熱処理する、ビスマス系酸化物超電導線材の製造方法であって、嵌合して多芯線とした後の伸線加工の工程において、減圧雰囲気中５５０℃〜７６０℃の温度で熱処理を施すことを特徴としている。
【００１１】
請求項３の発明によるビスマス系酸化物超電導線材の製造方法は、請求項２の発明において、嵌合して多芯線とする前の伸線加工の工程においても、減圧雰囲気中５５０℃〜７６０℃の温度で熱処理を施すことを特徴としている。
【００１２】
【作用】
この発明によれば、伸線加工の工程において、減圧雰囲気中熱処理が施される。この減圧雰囲気下での熱処理によって、原料粉末の吸着ガスを取除くことができ、従来のように圧延後の熱処理の際に生じる線材の膨張を防ぐことができる。
【００１３】
この脱ガスを目的とした熱処理は、原料粉末を金属シースにて被覆した後の伸線加工の工程において行なわれる。そのため、一旦取除かれたガスが、再び原料粉末に吸着することがない。また、この脱ガスのための熱処理は、圧延加工によって原料粉末の密度が高くなる前に行なわれる。そのため、吸着ガスを効率よく取除くことができる。
【００１４】
また、この発明によれば、この伸線加工の工程における熱処理は、５５０℃〜７６０℃の温度で行なわれる。そのため、原料粉末の特性に影響を及ぼすことなく、吸着ガスを効率よく取除くことができる。
【００１５】
一般に、原料粉末の真空雰囲気での融点は約７６０℃であり、熱処理は融点以下で行なうことが好ましい。一方、５５０℃より低い温度で熱処理を行なうと、超電導相が分解して非超電導相ができることにより臨界電流密度が減少してしまうため、熱処理は５５０℃以上で行なうことが好ましい。
【００１６】
【実施例】
（実施例１）
Ｂｉ２ Ｏ３ 、ＰｂＯ、ＳｒＣＯ３ 、ＣａＣＯ３ およびＣｕＯを用いて、Ｂｉ：Ｐｂ：Ｓｒ：Ｃａ：Ｃｕ＝１．８１：０．４０：１．９８：２．２１：３．０３の組成比になるように、これらを配合した。この配合した粉末を、大気中において、７５０℃で１２時間、８００℃で８時間、さらに、減圧雰囲気１Ｔｏｒｒにおいて、７６０℃で８時間、の順に熱処理を施した。なお、各熱処理後において、粉砕を行なった。このような熱処理および粉砕を経て得られた粉末を、さらに、ボールミルにより粉砕し、サブミクロンの粉末を得た。この粉末を８００℃で２時間熱処理を施した後、外径１２ｍｍ、内径９ｍｍの銀パイプ中に充填した。
【００１７】
この銀パイプ中に充填された粉末を、直径９ｍｍまで伸線した後、３Ｔｏｒｒの減圧雰囲気中、４００、５００、５５０、６００、６５０、７００、７５０および８００℃の各温度で、１０時間の熱処理を施した。続いて、このようにして得られたものを、直径１．０ｍｍになるまでさらに伸線加工した。
【００１８】
次に、この伸線加工後の線材を、厚さ０．１７ｍｍになるように圧延加工した後、８５０℃で５０時間の熱処理を施した。その後、さらに、厚さ０．１４ｍｍになるまで圧延加工し、８５０℃で５０時間の熱処理を施した。
【００１９】
このようにして、長さ１０ｍの長尺の酸化物超電導線材を作製し、得られた線材の臨界電流密度を測定した。その結果を図１に示す。図１において、横軸は伸線加工の工程において行なった熱処理の際の温度（℃）を示し、縦軸は得られた線材の臨界電流密度（×１０４ Ａ／ｃｍ２ ）を示している。また、熱処理を施さなかった場合の結果を、熱処理温度が０℃のときとみなして、併せて示している。
【００２０】
図１から明らかなように、減圧雰囲気中５５０℃〜７６０℃の温度で熱処理を施すことにより、酸化物超電導線材の臨界電流密度が向上することがわかる。
【００２１】
一方、伸線加工途中に熱処理を施さないほかは同様の条件で、長さ１０ｃｍの短尺の酸化物超電導線材を作製した。得られた線材の臨界電流密度を測定したところ、２．７×１０４ Ａ／ｃｍ２ であった。
【００２２】
このことから、長尺線材を製造する際、伸線加工の工程において、減圧雰囲気中５５０℃〜７６０℃の温度で熱処理を施すことにより、短尺線材とほぼ同等の性能が得られることがわかる。
【００２３】
（実施例２）
伸線加工の工程において行なう熱処理について、熱処理時間が臨界電流密度の向上に及ぼす影響について調べるため、以下の実験を行なった。
【００２４】
伸線加工の工程において行なう熱処理条件以外は実施例１と同様にして、長さが１０ｍの酸化物超電導線材を作製した。熱処理は、３Ｔｏｒｒの減圧雰囲気中６５０℃の温度で、それぞれ２．５、５、１０、５０および１００時間の条件で行なった。
【００２５】
このようにして得られた線材の臨界電流密度を測定した。その結果を図２に示す。図２において、横軸は伸線加工の工程において行なった熱処理時間（ｈｒ）を示し、縦軸は得られた線材の臨界電流密度（×１０４ Ａ／ｃｍ２ ）を示している。また、熱処理を施さなかった場合の結果を、熱処理時間が０時間として、併せて示す。
【００２６】
図２から明らかなように、６５０℃での熱処理は、約５時間以上行なえば臨界電流密度の向上に十分な効果があり、それ以上熱処理時間が長くなっても、効果に差はないことがわかる。
【００２７】
（実施例３）
Ｂｉ２ Ｏ３ 、ＰｂＯ、ＳｒＣＯ３ 、ＣａＣＯ３ およびＣｕＯを用いて、Ｂｉ：Ｐｂ：Ｓｒ：Ｃａ：Ｃｕ＝１．８１：０．４０：１．９８：２．２１：３．０３の組成比になるように、これらを配合した。この配合した粉末を、大気中において、７５０℃で１２時間、８００℃で８時間、さらに、減圧雰囲気１Ｔｏｒｒにおいて、７６０℃で８時間、の順に熱処理を施した。なお、各熱処理後において、粉砕を行なった。このような熱処理および粉砕を経て得られた粉末を、さらに、ボールミルにより粉砕し、サブミクロンの粉末を得た。この粉末を８００℃で２時間熱処理を施した後、外径１２ｍｍ、内径１０ｍｍの銀パイプ中に充填した。
【００２８】
この銀パイプ中に充填された粉末を、１ｍｍまで伸線加工した後、外径１２ｍｍ、内径９ｍｍの銀パイプに嵌合して、６１芯の多芯線とした。その後、この多芯線に対して、１Ｔｏｒｒの減圧雰囲気中、４００、５００、５５０、６００、６５０、７００、７５０および８００℃の各温度で、１０時間の熱処理を施した。続いて、このようにして得られたものを、直径１．０ｍｍになるまでさらに伸線加工した。
【００２９】
この伸線加工後の多芯線材を、厚さ０．２２ｍｍになるように圧延加工した後、８５０℃で５０時間の熱処理を施した。その後、さらに、厚さ０．２０ｍｍになるまで圧延加工し、８５０℃で５０時間の熱処理を施した。
【００３０】
このようにして、長さ５０ｍの長尺の酸化物超電導多芯線材を作製し、得られた線材の臨界電流密度を測定した。その結果を図３に示す。図３において、横軸は伸線加工の工程において行なった熱処理の際の温度（℃）を示し、縦軸は得られた線材の臨界電流密度（×１０４ Ａ／ｃｍ２ ）を示している。また、熱処理を施さなかった場合の結果を、熱処理温度が０℃のときとして、併せて示している。
【００３１】
図３から明らかなように、減圧雰囲気中５５０℃〜７６０℃の温度で熱処理を施すことにより、酸化物超電導線材の臨界電流密度が向上することがわかる。
【００３２】
一方、伸線加工途中に熱処理を施さないほかは同様の条件で、長さ１０ｃｍの短尺の酸化物超電導多芯線材を作製した。得られた線材の臨界電流密度を測定したところ、２．３×１０４ Ａ／ｃｍ２ であった。
【００３３】
このことから、長尺の多芯線材を製造する際、嵌合して多芯線とした後の伸線加工の工程において、減圧雰囲気中５５０℃〜７６０℃の温度で熱処理を施すことにより、短尺の多芯線材に近い性能が得られることがわかる。
【００３４】
（実施例４）
実施例３において、銀パイプ中に充填した粉末を嵌合して多芯線とする前の伸線加工の工程においても、３Ｔｏｒｒの減圧雰囲気中、６５０℃で１０時間の熱処理を施した。他の条件は実施例３と同様にして、長さが５０ｍの酸化物超電導多芯線材を作製した。
【００３５】
このようにして得られた線材について、臨界電流密度を測定した。その結果を図４に示す。図４において、横軸は伸線加工の工程において行なった熱処理の際の温度（℃）を示し、縦軸は得られた線材の臨界電流密度（×１０４ Ａ／ｃｍ２ ）を示している。また、熱処理を施さなかった場合の結果を、熱処理温度が０℃のときとみなして、併せて示している。
【００３６】
図４から明らかなように、嵌合して多芯線とする前の伸線加工の工程においても熱処理を施すことにより、酸化物超電導線材の臨界電流密度は、さらに向上することがわかる。
【００３７】
なお、以上の実施例に関する開示は、本発明の単なる具体例にすぎず、本発明の技術的範囲を何ら制限するものではない。
【００３８】
本発明は、ビスマス系酸化物超電導線材の製造に限られるものではなく、タリウム系およびイットリウム系酸化物超電導線材の製造に対しても適用可能である。しかしながら、イットリウム系酸化物超電導線材の製造においては、熱処理による酸素の脱離の可能性があり、一方、タリウム系酸化物超電導線材の製造においては、熱処理によるタリウムの蒸発の可能性がある。したがって、本発明は、ビスマス系酸化物超電導線材の製造への適用が、最も効果がある。
【００３９】
また、本発明において、伸線加工の工程における熱処理の際の真空度は、大気圧よりも減圧であれば有効であるが、数Ｔｏｒｒ以下であれば、より効率よく脱ガスを行なうことができる。
【００４０】
【発明の効果】
以上説明したように、この発明によれば、焼結のために行なわれる圧延後の熱処理の際に、線材が膨張することがない。
【００４１】
そのため、超電導特性の均一な長尺の線材を作製することができる。また、線材の膨張によって超電導体の組織が乱されることもないために、臨界電流密度の高い酸化物超電導線材が得られる。
【００４２】
したがって、この発明により製造された酸化物超電導線材は、ケーブルやマグネットへの適用が可能である。
【図面の簡単な説明】
【図１】熱処理温度と得られる酸化物超電導線材の臨界電流密度との関係を示す図である。
【図２】熱処理時間と得られる酸化物超電導線材の臨界電流密度との関係を示す図である。
【図３】熱処理温度と得られる酸化物超電導線材の臨界電流密度との関係を示す図である。
【図４】熱処理温度と得られる酸化物超電導線材の臨界電流密度との関係を示す図である。[0001]
[Industrial applications]
The present invention relates to a method for producing an oxide superconducting wire, and more particularly to a method for producing an oxide superconducting wire having a high critical current density.
[0002]
[Prior art]
In recent years, ceramic superconducting materials, that is, oxide superconducting materials, have attracted attention as superconducting materials exhibiting higher critical temperatures. Among them, yttrium shows a high critical temperature of about 90K, bismuth shows a high critical temperature of about 110K, and thallium shows a high critical temperature of about 120K, and practical application is expected.
[0003]
In these oxide superconducting materials, a single-core oxide superconducting material having a high critical current density is obtained by heat-treating a powder, coating it with a metal sheath, performing wire drawing and rolling, and further heat-treating. Wire rod is obtained. In addition, after heat-treating a powder containing an oxide superconducting material as a main component, covering with a metal sheath, performing wire drawing, fitting and forming a multi-core wire, performing wire drawing and rolling, and By performing the heat treatment, an oxide superconducting multi-core wire having a similarly high critical current density is obtained. Furthermore, conventionally, in the production of such an oxide superconducting wire, it is known that an oxide superconducting wire having a higher critical current density can be obtained by repeating the steps of rolling and heat treatment a plurality of times.
[0004]
[Problems to be solved by the invention]
When applying an oxide superconducting wire to a cable or a magnet, it is necessary to have a high critical current density in addition to a high critical temperature. In addition, a long oxide superconducting wire also needs to have uniform characteristics.
[0005]
The critical current density of the single-core and multi-core oxide superconducting wires manufactured by the above-described conventional method has a high value of 30,000 A / cm 2 or more in a short wire of about 10 cm.
[0006]
However, in the production of a long wire, a phenomenon occurs in which the wire swells during heat treatment after rolling performed for sintering. In the case of short wire rods, the gas adsorbed on the raw material powder in the process up to sintering escapes from both ends of the wire rod during the heat treatment. In this case, the wire does not come off sufficiently and expands in the wire. Then, there is a problem that the superconductivity of the wire becomes non-uniform due to the expansion of the wire. In addition, there is another problem that the critical current density is reduced because the superconductor structure is disturbed by the expansion of the wire.
[0007]
For these reasons, the critical current density of a long wire manufactured by a conventional method, for example, a 100 m-class oxide superconducting wire, was only about 10,000 A / cm 2 .
[0008]
An object of the present invention is to solve the above-mentioned problems and to provide a method for producing a long oxide superconducting wire having a high critical current density.
[0009]
[Means for Solving the Problems]
The method for producing a bismuth-based oxide superconducting wire according to the first aspect of the present invention includes the steps of: heat-treating a powder containing a bismuth-based oxide superconducting material as a main component, coating the powder with a metal sheath, and performing wire drawing and rolling. A method for producing a bismuth-based oxide superconducting wire, which is further subjected to a heat treatment, wherein the heat treatment is performed at a temperature of 550 ° C. to 760 ° C. in a reduced-pressure atmosphere in a wire drawing process.
[0010]
The method for producing a bismuth-based oxide superconducting wire according to the second aspect of the present invention is a method of manufacturing a bismuth-based oxide superconducting wire, which comprises heat-treating a powder containing a bismuth-based oxide superconducting material as a main component, coating the powder with a metal sheath, performing wire drawing, and then fitting. After multi-filament wire, after subjected to wire drawing and rolling, and further heat treatment, a method of manufacturing a bismuth-based oxide superconducting wire, in the wire drawing process after fitting and multi-core wire, The heat treatment is performed at a temperature of 550 ° C. to 760 ° C. in a reduced pressure atmosphere.
[0011]
The method of manufacturing a bismuth-based oxide superconducting wire according to the third aspect of the present invention is the method of the second aspect, wherein the wire drawing step before the fitting into a multi-core wire is performed at 550 ° C. to 760 ° C. in a reduced-pressure atmosphere. The heat treatment is performed at a temperature of
[0012]
[Action]
According to the present invention, in the wire drawing process, the heat treatment is performed in a reduced pressure atmosphere. By performing the heat treatment under the reduced pressure atmosphere, the adsorbed gas of the raw material powder can be removed, and the expansion of the wire rod that occurs during the heat treatment after rolling as in the related art can be prevented.
[0013]
The heat treatment for the purpose of degassing is performed in a wire drawing process after coating the raw material powder with a metal sheath. Therefore, the gas once removed does not adsorb again to the raw material powder. The heat treatment for degassing is performed before the density of the raw material powder is increased by rolling. Therefore, the adsorbed gas can be efficiently removed.
[0014]
Further, according to the present invention, the heat treatment in the wire drawing step is performed at a temperature of 550 ° C to 760 ° C. Therefore, the adsorbed gas can be efficiently removed without affecting the properties of the raw material powder.
[0015]
Generally, the melting point of the raw material powder in a vacuum atmosphere is about 760 ° C., and the heat treatment is preferably performed at a temperature lower than the melting point. On the other hand, if the heat treatment is performed at a temperature lower than 550 ° C., the critical current density is reduced because the superconducting phase is decomposed to form a non-superconducting phase. Therefore, the heat treatment is preferably performed at 550 ° C. or higher.
[0016]
【Example】
(Example 1)
Using Bi 2 O 3 , PbO, SrCO 3 , CaCO 3 and CuO, a composition ratio of Bi: Pb: Sr: Ca: Cu = 1.81: 0.40: 1.98: 2.21: 3.03 These were blended so that The compounded powder was heat-treated in the air in the order of 750 ° C. for 12 hours, 800 ° C. for 8 hours, and further at 760 ° C. for 8 hours in a reduced-pressure atmosphere of 1 Torr. Note that pulverization was performed after each heat treatment. The powder obtained through such heat treatment and pulverization was further pulverized by a ball mill to obtain a submicron powder. This powder was heat-treated at 800 ° C. for 2 hours, and then filled in a silver pipe having an outer diameter of 12 mm and an inner diameter of 9 mm.
[0017]
The powder filled in the silver pipe is drawn to a diameter of 9 mm, and then heat-treated for 10 hours at a temperature of 400, 500, 550, 600, 650, 700, 750 and 800 ° C. in a reduced-pressure atmosphere of 3 Torr. Was given. Subsequently, the wire thus obtained was further drawn until the diameter became 1.0 mm.
[0018]
Next, the wire after the drawing was rolled to a thickness of 0.17 mm, and then subjected to a heat treatment at 850 ° C. for 50 hours. After that, it was further rolled to a thickness of 0.14 mm and heat-treated at 850 ° C. for 50 hours.
[0019]
Thus, a long oxide superconducting wire having a length of 10 m was prepared, and the critical current density of the obtained wire was measured. The result is shown in FIG. In FIG. 1, the horizontal axis represents the temperature (° C.) during the heat treatment performed in the wire drawing process, and the vertical axis represents the critical current density (× 10 4 A / cm 2 ) of the obtained wire. . In addition, the results when no heat treatment is performed are also shown, assuming that the heat treatment temperature is 0 ° C.
[0020]
As is clear from FIG. 1, it is found that the heat treatment at a temperature of 550 ° C. to 760 ° C. in a reduced pressure atmosphere improves the critical current density of the oxide superconducting wire.
[0021]
On the other hand, a short oxide superconducting wire having a length of 10 cm was produced under the same conditions except that the heat treatment was not performed during the wire drawing. When the critical current density of the obtained wire was measured, it was 2.7 × 10 4 A / cm 2 .
[0022]
From this fact, it can be seen that, when a long wire is manufactured, by performing a heat treatment at a temperature of 550 ° C. to 760 ° C. in a reduced pressure atmosphere in a wire drawing step, almost the same performance as that of a short wire is obtained.
[0023]
(Example 2)
The following experiment was conducted to examine the effect of the heat treatment time on the improvement of the critical current density in the heat treatment performed in the wire drawing process.
[0024]
An oxide superconducting wire having a length of 10 m was prepared in the same manner as in Example 1 except for the heat treatment conditions performed in the wire drawing process. The heat treatment was performed in a reduced pressure atmosphere of 3 Torr at a temperature of 650 ° C. for 2.5, 5, 10, 50 and 100 hours, respectively.
[0025]
The critical current density of the wire thus obtained was measured. The result is shown in FIG. In FIG. 2, the horizontal axis represents the heat treatment time (hr) performed in the wire drawing step, and the vertical axis represents the critical current density (× 10 4 A / cm 2 ) of the obtained wire. In addition, the results when no heat treatment was performed are also shown, assuming that the heat treatment time is 0 hour.
[0026]
As is clear from FIG. 2, the heat treatment at 650 ° C. has a sufficient effect for improving the critical current density if performed for about 5 hours or more, and there is no difference in the effect even if the heat treatment time is longer than that. Understand.
[0027]
(Example 3)
Using Bi 2 O 3 , PbO, SrCO 3 , CaCO 3 and CuO, a composition ratio of Bi: Pb: Sr: Ca: Cu = 1.81: 0.40: 1.98: 2.21: 3.03 These were blended so that The compounded powder was heat-treated in the air in the order of 750 ° C. for 12 hours, 800 ° C. for 8 hours, and further at 760 ° C. for 8 hours in a reduced-pressure atmosphere of 1 Torr. Note that pulverization was performed after each heat treatment. The powder obtained through such heat treatment and pulverization was further pulverized by a ball mill to obtain a submicron powder. This powder was heat-treated at 800 ° C. for 2 hours, and then filled in a silver pipe having an outer diameter of 12 mm and an inner diameter of 10 mm.
[0028]
The powder filled in the silver pipe was drawn to 1 mm, and then fitted into a silver pipe having an outer diameter of 12 mm and an inner diameter of 9 mm to form a 61-core multicore wire. Thereafter, the multifilamentary wire was subjected to a heat treatment at 400, 500, 550, 600, 650, 700, 750 and 800 ° C. for 10 hours in a reduced-pressure atmosphere of 1 Torr. Subsequently, the wire thus obtained was further drawn until the diameter became 1.0 mm.
[0029]
The multifilamentary wire after the wire drawing was rolled to a thickness of 0.22 mm, and then subjected to a heat treatment at 850 ° C. for 50 hours. Thereafter, rolling was further performed until the thickness became 0.20 mm, and heat treatment was performed at 850 ° C. for 50 hours.
[0030]
In this way, a long oxide superconducting multi-core wire having a length of 50 m was produced, and the critical current density of the obtained wire was measured. The result is shown in FIG. In FIG. 3, the horizontal axis indicates the temperature (° C.) during the heat treatment performed in the wire drawing process, and the vertical axis indicates the critical current density (× 10 4 A / cm 2 ) of the obtained wire. . In addition, the results when no heat treatment is performed are also shown when the heat treatment temperature is 0 ° C.
[0031]
As is clear from FIG. 3, it is found that the heat treatment at a temperature of 550 ° C. to 760 ° C. in a reduced pressure atmosphere improves the critical current density of the oxide superconducting wire.
[0032]
On the other hand, a short oxide superconducting multi-core wire having a length of 10 cm was produced under the same conditions except that the heat treatment was not performed during the wire drawing. When the critical current density of the obtained wire was measured, it was 2.3 × 10 4 A / cm 2 .
[0033]
For this reason, when manufacturing a long multifilamentary wire, in the wire drawing process after fitting and forming a multifilamentary wire, by performing a heat treatment at a temperature of 550 ° C. to 760 ° C. in a reduced pressure atmosphere, It can be seen that the performance close to that of the multi-core wire can be obtained.
[0034]
(Example 4)
In Example 3, in the drawing process before fitting the powder filled in the silver pipe into a multi-core wire, a heat treatment was performed at 650 ° C. for 10 hours in a reduced-pressure atmosphere of 3 Torr. Other conditions were the same as in Example 3 to prepare a 50 m-long oxide superconducting multi-core wire.
[0035]
The critical current density of the wire thus obtained was measured. The result is shown in FIG. In FIG. 4, the horizontal axis represents the temperature (° C.) during the heat treatment performed in the wire drawing process, and the vertical axis represents the critical current density (× 10 4 A / cm 2 ) of the obtained wire. . In addition, the results when no heat treatment is performed are also shown, assuming that the heat treatment temperature is 0 ° C.
[0036]
As is clear from FIG. 4, it is found that the critical current density of the oxide superconducting wire is further improved by performing the heat treatment even in the wire drawing process before the fitting and forming the multi-core wire.
[0037]
It should be noted that the disclosure regarding the above embodiments is merely a specific example of the present invention, and does not limit the technical scope of the present invention in any way.
[0038]
The present invention is not limited to the production of bismuth-based oxide superconducting wires, but is also applicable to the production of thallium-based and yttrium-based oxide superconducting wires. However, in the production of an yttrium-based oxide superconducting wire, there is a possibility that oxygen is desorbed by heat treatment, while in the production of a thallium-based oxide superconducting wire, there is a possibility that thallium is evaporated by heat treatment. Therefore, the present invention is most effective when applied to the production of bismuth-based oxide superconducting wires.
[0039]
In the present invention, the degree of vacuum during the heat treatment in the wire drawing process is effective if the pressure is lower than the atmospheric pressure, but if the pressure is several Torr or less, degassing can be performed more efficiently. .
[0040]
【The invention's effect】
As described above, according to the present invention, the wire does not expand during the heat treatment after rolling performed for sintering.
[0041]
Therefore, a long wire having uniform superconducting characteristics can be manufactured. Further, since the structure of the superconductor is not disturbed by the expansion of the wire, an oxide superconducting wire having a high critical current density can be obtained.
[0042]
Therefore, the oxide superconducting wire manufactured according to the present invention can be applied to cables and magnets.
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between a heat treatment temperature and a critical current density of an obtained oxide superconducting wire.
FIG. 2 is a diagram showing a relationship between a heat treatment time and a critical current density of an obtained oxide superconducting wire.
FIG. 3 is a diagram showing a relationship between a heat treatment temperature and a critical current density of an obtained oxide superconducting wire.
FIG. 4 is a diagram showing a relationship between a heat treatment temperature and a critical current density of an obtained oxide superconducting wire.
Claims (3)
前記伸線加工の工程において、減圧雰囲気中５５０℃〜７６０℃の温度で熱処理を施すことを特徴とする、ビスマス系酸化物超電導線材の製造方法。 A method for producing a bismuth-based oxide superconducting wire, which comprises applying a heat treatment to a powder containing a bismuth-based oxide superconducting material as a main component, coating with a metal sheath, performing wire drawing and rolling, and further heat-treating. ,
A method for producing a bismuth-based oxide superconducting wire, wherein a heat treatment is performed in a reduced pressure atmosphere at a temperature of 550 ° C. to 760 ° C. in the wire drawing process.
前記嵌合して多芯線とした後の伸線加工の工程において、減圧雰囲気中５５０℃〜７６０℃の温度で熱処理を施すことを特徴とする、ビスマス系酸化物超電導線材の製造方法。After heat-treating a powder containing a bismuth-based oxide superconducting material as a main component, covering with a metal sheath, performing wire drawing and then fitting into a multi-core wire, performing wire drawing and rolling, and then further A method for producing a bismuth-based oxide superconducting wire to be heat-treated,
A method for producing a bismuth-based oxide superconducting wire, wherein a heat treatment is performed in a reduced-pressure atmosphere at a temperature of 550 ° C. to 760 ° C. in the wire drawing process after the fitting into a multi-core wire.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13022193A JP3574461B2 (en) | 1993-06-01 | 1993-06-01 | Manufacturing method of oxide superconducting wire |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13022193A JP3574461B2 (en) | 1993-06-01 | 1993-06-01 | Manufacturing method of oxide superconducting wire |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06342607A JPH06342607A (en) | 1994-12-13 |
| JP3574461B2 true JP3574461B2 (en) | 2004-10-06 |
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| JP13022193A Expired - Fee Related JP3574461B2 (en) | 1993-06-01 | 1993-06-01 | Manufacturing method of oxide superconducting wire |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| EP1528575A4 (en) | 2002-08-05 | 2007-02-07 | Sumitomo Electric Industries | Method of producing superconductive wire material |
| JP4701631B2 (en) * | 2004-05-13 | 2011-06-15 | 住友電気工業株式会社 | Superconducting wire manufacturing method |
| JP2006012537A (en) | 2004-06-24 | 2006-01-12 | Sumitomo Electric Ind Ltd | Method of producing superconducting wire |
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