JP3118922B2 - Heat treatment method for silver-coated oxide superconducting wire - Google Patents
Heat treatment method for silver-coated oxide superconducting wireInfo
- Publication number
- JP3118922B2 JP3118922B2 JP03340229A JP34022991A JP3118922B2 JP 3118922 B2 JP3118922 B2 JP 3118922B2 JP 03340229 A JP03340229 A JP 03340229A JP 34022991 A JP34022991 A JP 34022991A JP 3118922 B2 JP3118922 B2 JP 3118922B2
- Authority
- JP
- Japan
- Prior art keywords
- heat treatment
- silver
- wire
- temperature
- oxide superconducting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- 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
Landscapes
- Inorganic Compounds Of Heavy Metals (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
- Compositions Of Oxide Ceramics (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は銀被覆酸化物超電導線材
の熱処理方法に関し、特に、火膨れのない健全な線材が
得られると共に、Ｊｃ値（臨界電流密度）特性を向上さ
せることができる銀被覆酸化物超電導線材の熱処理方法
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heat-treating a silver-coated oxide superconducting wire, and more particularly to a silver capable of obtaining a sound wire without blistering and improving the Jc value (critical current density) characteristics. The present invention relates to a heat treatment method for a coated oxide superconducting wire.
【０００２】[0002]
【従来の技術】酸化物超電導体が液体窒素温度（７７
Ｋ）を越えるＴｃ（臨界温度）を有する物質として発見
されてから、世界各国でその実用化を目指した研究が行
われており、その中で銀被覆酸化物超電導線材（以下、
銀被覆線材と略記する）は酸化物超電導体を線材化する
上での有望な構造として注目されている。2. Description of the Related Art An oxide superconductor has a liquid nitrogen temperature (77 ° C.).
K), which has been discovered as a substance having a Tc (critical temperature) exceeding that of the superconducting silver-coated oxide superconducting wire (hereinafter, referred to as "superconducting wire").
(Abbreviated as silver-coated wire) is attracting attention as a promising structure for converting an oxide superconductor into a wire.
【０００３】銀被覆線材は、超電導性を示す粉末、例え
ば、Ｙ−Ｂａ−Ｃｕ−Ｏ系，Ｂｉ−（Ｐｂ）−Ｓｒ−Ｃ
ａ−Ｃｕ−Ｏ系，Ｔｌ−Ｂａ−（Ｓｒ）−Ｃａ−Ｃｕ−
Ｏ系等の粉末を銀管中に充填したものを、減面塑性加工
して線材とした後に、超電導体粒子間を電気的に接合さ
せるために焼結熱処理を施して成り、７７Ｋ，ＯＴにお
ける短尺でのＪｃ値（臨界電流密度）は、Ｙ−Ｂａ−Ｃ
ｕ−Ｏ系で２０００〜４０００Ａ／ｃｍ2 ，Ｂｉ−（Ｐ
ｂ）−Ｓｒ−Ｃａ−Ｃｕ−Ｏ系で１００００〜５０００
０Ａ／ｃｍ2 ，Ｔｌ−Ｂａ−（Ｓｒ）−Ｃａ−Ｃｕ−Ｏ
系で１００００〜３００００Ａ／ｃｍ2 となっている。[0003] The silver-coated wire is made of powder having superconductivity, for example, Y-Ba-Cu-O, Bi- (Pb) -Sr-C.
a-Cu-O system, Tl-Ba- (Sr) -Ca-Cu-
A material obtained by filling a silver tube with powder such as an O-based material is subjected to surface-reducing plastic working to form a wire, and then subjected to a sintering heat treatment to electrically connect the superconductor particles. Jc value (critical current density) in a short length is Y-Ba-C
2000-4000 A / cm 2 , Bi- (P
b) -Sr-Ca-Cu-O system of 10,000 to 5000
0A / cm 2 , Tl-Ba- (Sr) -Ca-Cu-O
It is 10,000 to 30,000 A / cm 2 in the system.
【０００４】最近になってこれらの銀被覆線材は液体ヘ
リウムで冷却することによって磁場中でのＪｃ値特性が
飛躍的に向上することが判ってきた。特に、Ｂｉ−（Ｐ
ｂ）−Ｓｒ−Ｃａ−Ｃｕ−Ｏ系の銀被覆線材は、４．２
Ｋ，１０Ｔ以上において、１０4 Ａ／ｃｍ2 を越えるＪ
ｃ値を得ることができ、また、ドクターブレード法によ
るＢｉ2 Ｓｒ2 Ｃａ1 Ｃｕ2 Ｏx （以下、Ｂｉ−２２１
２という）／Ａｇ複合超電導テープではその熱処理にお
いて部分溶融温度から徐冷する（以下、部分溶融−徐冷
熱処理という）ことにより更に特性を向上させ、４．２
Ｋ，２０Ｔ以上において１０5 Ａ／ｃｍ2 のＪｃ値を得
ることができる。Recently, it has been found that Jc value characteristics in a magnetic field can be dramatically improved by cooling these silver-coated wires with liquid helium. In particular, Bi- (P
b) -Sr-Ca-Cu-O-based silver-coated wire rod is 4.2
J exceeding 10 4 A / cm 2 at K, 10T or more
c value, and Bi 2 Sr 2 Ca 1 Cu 2 O x (hereinafter referred to as Bi-221) by a doctor blade method.
2) / Ag composite superconducting tape, its properties are further improved by gradually cooling from the partial melting temperature in the heat treatment (hereinafter, referred to as partial melting-slow cooling heat treatment).
A Jc value of 10 5 A / cm 2 can be obtained at K, 20T or more.
【０００５】しかし、ドクターブレード法による銀複合
超電導テープは、超電導体が剥き出しのままになってい
るため、安定性や、機械的（物質的）保護の観点から実
用化するには好ましくない。従って、Ｂｉ−２２１２に
対する部分溶融−徐冷熱処理を銀被覆線材に適用した銀
被覆線材によって性能向上を図ることが考えられる。[0005] However, the silver composite superconducting tape by the doctor blade method is not preferable for practical use from the viewpoint of stability and mechanical (material) protection since the superconductor remains exposed. Therefore, it is conceivable to improve the performance by using a silver-coated wire obtained by applying the partial melting-annealing heat treatment to Bi-2212 to the silver-coated wire.
【０００６】[0006]
【発明が解決しようとする課題】しかし、Ｂｉ−２２１
２に対する部分溶融−徐冷熱処理を銀被覆線材に適用し
ようとすると、Ｂｉ−２２１２に対して部分溶融時に酸
素の出入りがあるため、そのガス圧によって線材が火膨
れしてしまい健全な線材を得ることが困難となってい
る。また、このときのＪｃ値特性は、４．２Ｋ，１０Ｔ
において１００００〜２００００Ａ／ｃｍ2 と低迷した
ものになっている。However, Bi-221
When applying the partial melting-annealing heat treatment to silver-coated wire 2 for oxygen, oxygen enters and exits from Bi-2212 at the time of partial melting, so that the wire expands due to the gas pressure and a healthy wire is obtained. It has become difficult. The Jc value characteristic at this time is 4.2K, 10T
In this case, it was as low as 10,000 to 20,000 A / cm 2 .
【０００７】従って、本発明の目的は火膨れのない健全
な線材が得られると共に、Ｊｃ値特性を向上させること
ができる銀被覆酸化物超電導線材の熱処理方法を提供す
ることである。Accordingly, an object of the present invention is to provide a method of heat treating a silver-coated oxide superconducting wire which can obtain a sound wire without blistering and can improve the Jc value characteristics.
【０００８】[0008]
【課題を解決するための手段】本発明は上記問題点に鑑
み、火膨れのない健全な線材を得ながらＪｃ値特性を向
上させるため、本焼成を行う前に、本焼成温度より３０
℃以内の低めの温度で熱処理を行い、一度室温近くまで
冷却するようにした銀被覆酸化物超電導線材の熱処理方
法を提供するものである。SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention improves the Jc value characteristics while obtaining a sound wire without blistering, so that the firing temperature is reduced by 30% or less before the main firing.
An object of the present invention is to provide a method for heat-treating a silver-coated oxide superconducting wire, which is heat-treated at a lower temperature of not more than ° C and once cooled to near room temperature.
【０００９】銀被覆酸化物超電導線材としては、液体窒
素温度以上のＴｃを有する材料を用いれば特に限定する
ものではない。また、線材の構造としては単芯線，多芯
線等を適用することができる。更に、この熱処理方法を
Ｗ＆Ｒ，及びＲ＆Ｗ法におけるコイル熱処理法に適用し
ても良い。The silver-coated oxide superconducting wire is not particularly limited as long as a material having a Tc of liquid nitrogen temperature or higher is used. In addition, a single-core wire, a multi-core wire, or the like can be applied as the structure of the wire. Further, this heat treatment method may be applied to the coil heat treatment method in the W & R and R & W methods.
【００１０】[0010]
【実施例】以下、本発明の銀被覆酸化物超電導線材の熱
処理方法を図面を参照しつつ詳細に説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for heat treating a silver-coated oxide superconducting wire according to the present invention will be described below in detail with reference to the drawings.
【００１１】Ｂｉ−２２１２／Ａｇ被覆超電導線を用い
て、部分溶融−徐冷熱処理と、本発明による熱処理を行
った。Using a Bi-2212 / Ag-coated superconducting wire, a partial melting-slow cooling heat treatment and a heat treatment according to the present invention were performed.
【００１２】図１には本発明による熱処理を行ったとき
の温度分布が示されている。まず、部分溶融温度８７５
℃を基準として、それより３０℃以内の低めの温度（８
５５〜８７５℃）で熱処理を行い、一度室温近くまで冷
却してから本焼成を行いＢｉ−２２１２／Ａｇシース線
を得た。本焼成は８７５〜８９０℃の所定の時間の熱処
理と、１時間当り５℃の温度勾配による８１５〜８６０
℃までの徐冷と、その温度の所定の時間の維持を含む。FIG. 1 shows a temperature distribution when the heat treatment according to the present invention is performed. First, the partial melting temperature 875
° C, a lower temperature within 30 ° C (8 ° C)
(55-875 [deg.] C.), and once cooled to near room temperature, the main firing was performed to obtain a Bi-2212 / Ag sheath wire. The main baking is performed by a heat treatment for a predetermined time of 875 to 890 ° C. and a temperature gradient of 815 to 860 by a temperature gradient of 5 ° C. per hour.
This includes slow cooling to ℃ and maintaining the temperature for a predetermined time.
【００１３】図２には部分溶融−徐冷熱処理を行ったと
きの温度分布が示されている。まず最初に、Ｂｉ−２２
１２が部分溶融する８７５℃以上の温度（８７５〜９０
５℃）まで昇温させ、その温度を一定時間保持した後、
１時間当り２．５〜１０℃の温度勾配で部分溶融したＢ
ｉ−２２１２が再結晶して十分に配向成長する温度（８
１５〜８７０℃）まで徐冷し、その温度を一定時間保持
してＢｉ−２２１２／Ａｇシース線を得た。FIG. 2 shows a temperature distribution when the partial melting and annealing heat treatment is performed. First, Bi-22
12 is partially melted at a temperature of 875 ° C or more (875 to 90 ° C).
5 ° C), and after maintaining the temperature for a certain period of time,
B partially melted at a temperature gradient of 2.5 to 10 ° C. per hour
The temperature at which i-2212 recrystallizes and grows sufficiently in orientation (8
(15-870 ° C.), and the temperature was maintained for a certain period of time to obtain a Bi-2212 / Ag sheath wire.
【００１４】部分溶融−徐冷熱処理によって得られたＢ
ｉ−２２１２／Ａｇシース線は、部分溶融時に酸素解離
によって線材中のガス圧が高まるため、線材が火膨れし
てしまい健全な線材を得ることができなかった。しか
し、本発明の熱処理によって得られたＢｉ−２２１２／
Ａｇシース線にあっては、火膨れのない健全な線材を得
ることができた。B obtained by partial melting-annealing heat treatment
In the i-2212 / Ag sheath wire, since the gas pressure in the wire increases due to oxygen dissociation during partial melting, the wire swells and a healthy wire cannot be obtained. However, Bi-2212 / obtained by the heat treatment of the present invention.
In the case of the Ag sheath wire, a healthy wire without blister could be obtained.
【００１５】次に、前熱処理を加える本発明の熱処理に
よって得られた銀被覆線材と、前熱処理を加えない熱処
理によって得られた銀被覆線材のＪｃ値特性を比較する
ために、４．２Ｋ磁場中でのＪｃ値を測定した。図３は
その測定結果を示し、本発明の熱処理は、前熱処理を加
えない熱処理に比べて高いＪｃ値が得られることが判
る。Next, in order to compare the Jc value characteristics of the silver-coated wire obtained by the heat treatment according to the present invention with the pre-heat treatment and the silver-coated wire obtained by the heat treatment without the pre-heat treatment, a 4.2K magnetic field was used. Jc value was measured. FIG. 3 shows the measurement results, and it can be seen that the heat treatment of the present invention can obtain a higher Jc value than the heat treatment without the pre-heat treatment.
【００１６】また、前熱処理を加える本発明の熱処理に
よって得られた銀被覆線材と、前熱処理を加えない熱処
理によって得られた銀被覆線材の横破断面を観察した。
その結果を図４の(a),(b) に示す。(a) の前熱処理を加
えない熱処理では、Ａｇシースとの界面付近に僅かな板
状配向結晶組織が見られるが、中心部の大部分は無配向
組織であり、大きなボイド，或いはクラックが発生して
いることが分かる。これに対し、(b) の本発明による熱
処理では、一面にわたって板状結晶の配向組織を有して
いることが分かる。The cross-sections of the silver-coated wire obtained by the heat treatment of the present invention with the pre-heat treatment and the silver-coated wire obtained by the heat treatment without the pre-heat treatment were observed.
The results are shown in FIGS. 4 (a) and 4 (b). In the heat treatment without pre-heat treatment (a), a slight plate-like crystallographic structure is observed near the interface with the Ag sheath, but most of the central part is a non-oriented structure, and large voids or cracks are generated. You can see that it is doing. On the other hand, it can be seen that the heat treatment according to the present invention (b) has a plate-like crystal oriented structure over one surface.
【００１７】以上説明したように、本発明の前熱処理を
加えた熱処理を行うことにより、火膨れのない健全な線
材が得られると共に、Ｊｃ値特性の向上を図れ、かつ、
ボイド，或いはクラック等がない品質が良好な銀被覆線
材を得ることができる。As described above, by performing the heat treatment to which the pre-heat treatment of the present invention is applied, a sound wire having no blister can be obtained, and the Jc value characteristics can be improved.
A silver-coated wire having good quality without voids or cracks can be obtained.
【００２２】[0022]
【発明の効果】以上説明した通り、本発明の銀被覆酸化
物超電導線材の熱処理方法によると、本焼成の前に、本
焼成温度より３０℃以内の低めの温度で熱処理を行い、
一度室温近くまで冷却するようにしたため、火膨れのな
い健全な線材を得ることができると共に、磁場中でのＪ
ｃ値特性を向上させることができる。As described above, according to the heat treatment method for a silver-coated oxide superconducting wire of the present invention, a heat treatment is performed at a temperature lower than the main firing temperature by 30 ° C. or lower before the main firing.
Once cooled to near room temperature, a healthy wire without blisters can be obtained, and J
The c-value characteristics can be improved.
【図１】本発明にる熱処理の温度分布を表すグラフ。FIG. 1 is a graph showing a temperature distribution of a heat treatment according to the present invention.
【図２】部分溶融−徐冷熱処理の温度分布を表すグラ
フ。FIG. 2 is a graph showing a temperature distribution of a partial melting-annealing heat treatment.
【図３】前熱処理を行った場合と行わなかった場合の磁
場中でのＪｃ値を表すグラフ。FIG. 3 is a graph showing Jc values in a magnetic field when a pre-heat treatment is performed and when a pre-heat treatment is not performed.
【図４】前熱処理を行った場合と行わなかった場合の横
破断面を表すＳＥＭ観察像。FIG. 4 is an SEM observation image showing a transverse fracture surface when a pre-heat treatment is performed and when it is not performed.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平３−250509（ＪＰ，Ａ) 特開 平４−71113（ＪＰ，Ａ) 特開 平４−121912（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01B 13/00 565 H01B 12/04 ZAA ＪＩＣＳＴファイル（ＪＯＩＳ)────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-250509 (JP, A) JP-A-4-71113 (JP, A) JP-A-4-121912 (JP, A) (58) Field (Int.Cl. 7 , DB name) H01B 13/00 565 H01B 12/04 ZAA JICST file (JOIS)
Claims (1)
間を電気的に接合する銀被覆酸化物超電導線材の熱処理
方法において、 前記超電導体粒子間を電気的に接合する本焼成温度より
３０℃以内の低めの温度で熱処理を行い、室温近くまで
冷却し、その後前記本焼成を行うことを特徴とする銀被
覆酸化物超電導線材の熱処理方法。1. A method for heat-treating a silver-coated oxide superconducting wire for electrically joining superconducting particles of a silver-coated oxide superconducting wire, comprising: 30 ° C. below a main firing temperature for electrically joining the superconducting particles. A heat treatment at a lower temperature within the range, cooling to near room temperature, and then performing the main baking.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03340229A JP3118922B2 (en) | 1991-11-29 | 1991-11-29 | Heat treatment method for silver-coated oxide superconducting wire |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03340229A JP3118922B2 (en) | 1991-11-29 | 1991-11-29 | Heat treatment method for silver-coated oxide superconducting wire |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05151844A JPH05151844A (en) | 1993-06-18 |
| JP3118922B2 true JP3118922B2 (en) | 2000-12-18 |
Family
ID=18334936
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03340229A Expired - Fee Related JP3118922B2 (en) | 1991-11-29 | 1991-11-29 | Heat treatment method for silver-coated oxide superconducting wire |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3118922B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5296459A (en) * | 1992-06-19 | 1994-03-22 | Trustees Of Boston University | Method for making an electrically conductive contact for joining high T.sub. |
-
1991
- 1991-11-29 JP JP03340229A patent/JP3118922B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05151844A (en) | 1993-06-18 |
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