JPH0580428B2 - - Google Patents
Info
- Publication number
- JPH0580428B2 JPH0580428B2 JP62170395A JP17039587A JPH0580428B2 JP H0580428 B2 JPH0580428 B2 JP H0580428B2 JP 62170395 A JP62170395 A JP 62170395A JP 17039587 A JP17039587 A JP 17039587A JP H0580428 B2 JPH0580428 B2 JP H0580428B2
- Authority
- JP
- Japan
- Prior art keywords
- superconducting
- powder
- phase
- temperature
- low
- 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 - Lifetime
Links
- 239000000843 powder Substances 0.000 claims description 27
- 239000000919 ceramic Substances 0.000 claims description 14
- 239000002994 raw material Substances 0.000 claims description 11
- 238000005245 sintering Methods 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 3
- 238000000034 method Methods 0.000 description 12
- 229910052760 oxygen Inorganic materials 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 239000013078 crystal Substances 0.000 description 7
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical group [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 238000001354 calcination Methods 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 229910020012 Nb—Ti Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009770 conventional sintering Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000001513 hot isostatic pressing Methods 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 230000029052 metamorphosis Effects 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000003963 x-ray microscopy Methods 0.000 description 1
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
- Compositions Of Oxide Ceramics (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
Description
利用産業分野
この発明は、マイスナー効果を呈する超電導セ
ラミツクスの製造方法に係り、得られた焼結体全
体が、超電導性を有する低温安定相からなる
BaO−Y2O3−CuO背景技術
系超電導セラミツクスの製造方法に関する。
従来、超電導材料としてはNb−Ti、Nb−Sn、
Nb3Sn等の合金系あるいは金属間化合物材料が知
られている。
前記超電導材料は、電気抵抗が零になる臨界温
度（Tc）がせいぜい30Kでマイスナー効果を示
すものであつた。
しかし、最近、臨界温度（Tc）が90K付近で
マイスナー効果を示す、高温超電導材料として、
BaO−Y2O3−CuO系超電導セラミツクスが提案
され、多くの研究調査が行われるようになつた。
このBaO−Y2O3−CuO系超電導セラミツクス、
例えば、YBa2Cu3O7-Xセラミツクスは550℃〜
600℃付近で相転移が行われ、この場合、高温相
の正方組織では超電導相が示さず、低温安定相の
斜方晶組織が超電導相を示すことが知られてい
る。
一方、かかる超電導セラミツクスの焼成に関
し、従来の粉末治金法による焼結法では、950℃
付近で焼結し、その後冷却する方法が取られてい
た。
この焼結に際し、正方晶組織の高温相から斜方
晶組織の低温安定相への変態の際に酸素の吸収が
行われる。
ところが、変態時の供給酸素が不足した場合、
低温においても、正方晶組織が準安定相として存
在し、特に、緻密な焼結体においては内部まで酸
素を供給することができず、得られた焼結体の全
体を超電導相の斜方晶組織に変態させることは困
難であつた。
発明の目的
この発明は、BaO−Y2O3−CuO系超電導セラ
ミツクスの製造に際して、得られた焼結体の全体
を超電導相の斜方晶組織に変態できる超電導セラ
ミツクスの製造方法を目的としている。
発明の概要
この発明は、
粒度3μｍ以下のYBa2Cu3O7-X組成（ｘ＝０〜
0.25）でかつ低温安定相からなる原料粉末を、
O220vol％以上含有の雰囲気中で、圧力200Kg／
cm2〜2000Kg／cm2で550℃〜600℃にて加圧焼結する
ことを特徴とする超電導セラミツクスの製造方法
である。
発明の構成
この発明を詳述すると、まず、BaO−Y2O3−
CuO系超電導セラミツクスの出発原料である
BaCO3、Y2O3、CuOを所要量混合後、下記の角
仮焼方法によつて、斜方晶組織よりなる低温安定
相を有する仮焼粉を得る。
すなわち、仮焼時、配合原料粉末と供給O2と
の接触が密になる如く、かつ配合原料中の
BaCO3が分解後、発生CO2ガスと再反応して
BaCO3の生成を防止するため、以下の仮焼方法
を適用する。
配合原料粉末を傾斜型回転炉の上方より投入
して、落下中の前記粉末を850℃〜1000℃の温
度条件にて、大気圧以上の100vol％O2雰囲気
と十分接触させて、仮焼粉末を前記低温安定相
にする方法
配合原料粉末を収容した容器の下方より、大
気圧以上の100vol％O2雰囲気を吹込んで、前
記雰囲気により前記粉末を撹拌させつつ、850
℃〜1000℃にて仮焼する方法
配合原料粉末を真空中で700℃まで昇温後、
100vol％O2雰囲気中で750〜900℃に１時間以
上保持後、前記O2雰囲気中にて炉冷し、仮焼
粉末を前記低温安定相にする方法
かかる３方法により得られた斜方晶からなる低
温安定相の仮焼粉末を微粉砕して粒度3μｍ以下
にした後、前記仮焼粉末をO220vol％以上含有の
雰囲気中で、圧力200Kg／cm2〜2000Kg／cm2で550℃
〜600℃にて加圧して、超電導性を有する低温安
定相からなるBaO−Y2O3−CuO系超電導セラミ
ツクスを得ることができる。
この発明において、加圧焼結方法は熱間静水圧
プレス法、ホツトプレス法のいずれでよい。
限定理由
この発明において、仮焼原料粉末の粒度を3μ
ｍ以下に限定した理由は、3μｍを越えると、原
料粒大部で超電導相と非超電導相とに分れること
があり、粒子全体として均一に超電導相が得られ
難いためである。
加熱焼結時の雰囲気が、O220vol％未満では、
降温時の正方晶→斜方晶への転移の際の酸素吸収
に際して、酸素が不足する場合があり好ましくな
く、O2雰囲気はO220vol％以上含有とする必要が
ある。
加圧焼結における圧力は、200Kg／cm2未満では、
粉体が緻密化せず加圧焼結の効果が認められず、
2000Kg／cm2を越えると、加圧装置自体が実用的で
なくなり好ましくない。
温度条件は、550℃未満では、十分なる密度を
持つたセラミツクスが得られず、600℃を越える
と、正方晶への転移が起こりやすくなるので好ま
しくない。
発明の効果
この発明は、配合原料粉末の仮焼粉末が斜方晶
の超電導相であり、かつ配合原料粉末は超電導相
が安定な温度領域で加圧焼結されるため、超電導
相を有する斜方晶が非超電導相の正方晶へ変態す
ることが抑制され、焼結体全体が均質な超電導相
からなり、高い臨界電流（Jc）を有する超電導材
料を得ることができる。
実施例
純度99.9％以上の粒度2μｍ以下のBaCO3、
Y2O3、CuO粉末を、組成比２：１：３のモル比
に配合して、アルコールを収容したボールミル中
で、６時間混合した後、乾燥させた。
さらに、径100mm×長さ４ｍ、傾斜角25゜の傾斜
難回転炉を用い、炉の上方より下方へ、前記配合
原料粉末を落下させつつ、100vol％O2雰囲気中
で、前記回転炉を回転させながら、930℃、20時
間の仮焼を行なつた。
その後、600℃まで冷却速度200℃／Hrにて冷
却し、さらに、580℃に10時間保持した後、室温
まで炉冷し、仮焼粉を得た。
前記仮焼粉をＸ線回折法にて結晶構造を調査し
た結果、斜方晶からなる低温安定相組織であつ
た。
前記仮焼粉を乾式にて、平均粒度1.5μｍに微粉
砕した。
微粉砕粉を、寸法径200mmφ、高さ10mm寸法、
材質SiCからなるダイスに装入し、100vol％O2雰
囲気中で、590℃まで100℃／Hrの条件にて加熱
後、590℃で圧力500Kg／cm2にて10時間保持して、
加圧焼結を行つた。
その後、炉冷して、寸法径15mmφ、高さ６mmの
焼結体を得た。
得られた焼結体をＸ線回析及び顕微鏡にて組
織、結晶構造を調査した結果、焼結体は斜方晶の
低温安定相組織を示すことは明らかであり、Tc
は87〓でマイスナー効果を示す超電導セラミツク
スが得られた。
（比較例）
実施例と同一組成比の純度99.9％以上の粒度2μ
ｍ以下のBaCO3、Y2O3、CuO粉末を混合後、実
施例と同一条件にて仮焼冷却を行つて、実施例と
同一の結晶構造を有する低温安定相組織にした
後、前記仮焼粉を乾式にて、平均粒度1.5μｍに微
粉砕した後、実施例と同一の寸法、材質のダイス
内に前記微砕粉を装入後、第１表の如き加熱条件
にて加熱後、第１表の如き加圧焼結条件にて、焼
結後、炉冷して焼結体を得た。
得られた焼結体をＸ線回析及び顕微鏡にて、調
査した結果の性状を第２表に表す。
Field of Application This invention relates to a method for producing superconducting ceramics exhibiting the Meissner effect, in which the entire obtained sintered body consists of a low-temperature stable phase having superconductivity.
The present invention relates to a method for producing BaO-Y 2 O 3 -CuO background technology superconducting ceramics. Conventionally, superconducting materials include Nb-Ti, Nb-Sn,
Alloy-based or intermetallic compound materials such as Nb 3 Sn are known. The superconducting material exhibits the Meissner effect when the critical temperature (Tc) at which the electrical resistance becomes zero is at most 30K. However, recently, high-temperature superconducting materials that exhibit the Meissner effect at a critical temperature (Tc) of around 90K have been developed.
BaO-Y 2 O 3 -CuO-based superconducting ceramics have been proposed, and many research studies have begun. This BaO−Y 2 O 3 −CuO based superconducting ceramic,
For example, YBa 2 Cu 3 O 7-X ceramics can be heated to 550℃~
It is known that a phase transition occurs at around 600°C, and in this case, the high-temperature phase of the tetragonal structure does not exhibit a superconducting phase, while the low-temperature stable phase of the orthorhombic structure exhibits a superconducting phase. On the other hand, regarding the firing of such superconducting ceramics, the conventional sintering method using powder metallurgy is not possible at 950°C.
The method used was to sinter the material nearby and then cool it. During this sintering, oxygen is absorbed during transformation from a high-temperature phase with a tetragonal structure to a low-temperature stable phase with an orthorhombic structure. However, if the oxygen supply during metamorphosis is insufficient,
Even at low temperatures, the tetragonal structure exists as a metastable phase, and in particular, in dense sintered bodies, oxygen cannot be supplied to the inside, and the entire sintered body is transformed into a superconducting orthorhombic phase. It was difficult to transform the organization. Purpose of the Invention The object of the present invention is to provide a method for manufacturing superconducting ceramics that can transform the entire obtained sintered body into an orthorhombic structure of a superconducting phase when manufacturing BaO-Y 2 O 3 -CuO-based superconducting ceramics. . Summary of the Invention This invention provides YBa 2 Cu 3 O 7-X composition (x=0 to
0.25) and a low-temperature stable phase,
In an atmosphere containing 20vol% or more of O 2 at a pressure of 200Kg/
This is a method for producing superconducting ceramics characterized by pressure sintering at 550° C. to 600° C. at cm 2 to 2000 Kg/cm 2 . Structure of the Invention To explain this invention in detail, first, BaO−Y 2 O 3 −
It is the starting material for CuO-based superconducting ceramics.
After mixing the required amounts of BaCO 3 , Y 2 O 3 and CuO, a calcined powder having a low-temperature stable phase consisting of an orthorhombic structure is obtained by the following square calcining method. In other words, during calcination, the blended raw material powder is in close contact with the supplied O2 , and the blended raw material is
After BaCO 3 decomposes, it re-reacts with the generated CO 2 gas.
In order to prevent the formation of BaCO 3 , the following calcination method is applied. The blended raw material powder is introduced from above into a tilted rotary furnace, and the falling powder is brought into sufficient contact with a 100 vol% O 2 atmosphere of atmospheric pressure or higher at a temperature of 850°C to 1000°C, and then calcined into powder. Method for converting into the low-temperature stable phase: Blow in an atmosphere of 100 vol% O 2 at atmospheric pressure or higher from the bottom of the container containing the mixed raw material powder, and while stirring the powder with the atmosphere,
Method of calcining at ℃~1000℃ After heating the blended raw material powder to 700℃ in vacuum,
A method of keeping the calcined powder at 750 to 900°C for 1 hour or more in a 100vol% O 2 atmosphere and then cooling it in a furnace in the O 2 atmosphere to make the calcined powder into the low-temperature stable phase. Orthorhombic crystals obtained by these three methods After finely pulverizing the calcined powder in a low-temperature stable phase to a particle size of 3 μm or less, the calcined powder was pulverized at 550°C at a pressure of 200 Kg/cm 2 to 2000 Kg/cm 2 in an atmosphere containing 20 vol% or more of O 2 .
By pressurizing at ~600°C, BaO-Y 2 O 3 -CuO-based superconducting ceramics consisting of a low-temperature stable phase having superconductivity can be obtained. In this invention, the pressure sintering method may be either a hot isostatic pressing method or a hot pressing method. Reason for limitation In this invention, the particle size of the calcined raw material powder is 3 μm.
The reason why it is limited to less than m is that if it exceeds 3 μm, most of the raw material particles may be separated into a superconducting phase and a non-superconducting phase, making it difficult to obtain a uniform superconducting phase throughout the particles. If the atmosphere during heating and sintering contains less than 20vol% O2 ,
Oxygen absorption during the transition from tetragonal to orthorhombic when the temperature is lowered may lead to a lack of oxygen, which is undesirable, and the O 2 atmosphere must contain 20 vol% or more of O 2 . When the pressure in pressure sintering is less than 200Kg/ cm2 ,
The powder did not become densified and the effect of pressure sintering was not observed.
If it exceeds 2000 Kg/cm 2 , the pressurizing device itself becomes unpractical, which is not preferable. As for temperature conditions, if the temperature is less than 550°C, ceramics with sufficient density cannot be obtained, and if it exceeds 600°C, transition to tetragonal crystals tends to occur, which is not preferable. Effects of the Invention This invention has an orthorhombic superconducting phase in the calcined powder of the blended raw material powder, and the blended raw material powder is pressure sintered in a temperature range where the superconducting phase is stable. Transformation of the square crystals into tetragonal crystals of a non-superconducting phase is suppressed, the entire sintered body consists of a homogeneous superconducting phase, and a superconducting material having a high critical current (Jc) can be obtained. Example BaCO 3 with a purity of 99.9% or more and a particle size of 2 μm or less,
Y 2 O 3 and CuO powder were mixed in a molar ratio of 2:1:3, mixed for 6 hours in a ball mill containing alcohol, and then dried. Furthermore, using a difficult-to-rotate furnace with a diameter of 100 mm x length of 4 m and an inclination angle of 25 degrees, the rotary furnace was rotated in a 100 vol% O 2 atmosphere while dropping the blended raw material powder from the top of the furnace to the bottom. Calcining was carried out at 930°C for 20 hours. Thereafter, it was cooled to 600°C at a cooling rate of 200°C/Hr, and further maintained at 580°C for 10 hours, and then cooled in a furnace to room temperature to obtain a calcined powder. The crystal structure of the calcined powder was investigated by X-ray diffraction, and it was found to have a low-temperature stable phase structure consisting of orthorhombic crystals. The calcined powder was dry-pulverized to an average particle size of 1.5 μm. Finely pulverized powder is 200mmφ in diameter and 10mm in height.
The material was charged into a die made of SiC, heated to 590℃ at 100℃/Hr in a 100vol% O 2 atmosphere, and then held at 590℃ and a pressure of 500Kg/cm 2 for 10 hours.
Pressure sintering was performed. Thereafter, it was cooled in a furnace to obtain a sintered body with a diameter of 15 mm and a height of 6 mm. As a result of investigating the structure and crystal structure of the obtained sintered body using X-ray diffraction and microscopy, it was clear that the sintered body showed an orthorhombic low-temperature stable phase structure, and Tc
Superconducting ceramics exhibiting the Meissner effect were obtained at 87〓. (Comparative example) Particle size 2μ with purity of 99.9% or more with the same composition ratio as the example
After mixing BaCO 3 , Y 2 O 3 , and CuO powder in an amount of less than After dry-pulverizing the baked powder to an average particle size of 1.5 μm, the pulverized powder was charged into a die with the same dimensions and material as in the example, and after heating under the heating conditions shown in Table 1, After sintering under the pressure sintering conditions shown in Table 1, the material was cooled in a furnace to obtain a sintered body. The properties of the obtained sintered body were investigated using X-ray diffraction and a microscope, and the properties thereof are shown in Table 2.
【表】【table】
Claims (1)
温安定相からなる原料粉末を、O220vol％以上含
有の雰囲気中で、圧力200Kg／cm2〜2000Kg／cm2で
550℃〜600℃に加圧焼結することを特徴とする超
電導セラミツクスの製造方法。1. A raw material powder with a YBa 2 Cu 3 O 7-X composition with a particle size of 3 μm or less and a low-temperature stable phase is heated at a pressure of 200 Kg/cm 2 to 2000 Kg/cm 2 in an atmosphere containing 20 vol% or more of O 2 .
A method for producing superconducting ceramics characterized by pressure sintering at 550°C to 600°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62170395A JPS6414157A (en) | 1987-07-08 | 1987-07-08 | Production of superconducting ceramic |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62170395A JPS6414157A (en) | 1987-07-08 | 1987-07-08 | Production of superconducting ceramic |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6414157A JPS6414157A (en) | 1989-01-18 |
| JPH0580428B2 true JPH0580428B2 (en) | 1993-11-09 |
Family
ID=15904132
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62170395A Granted JPS6414157A (en) | 1987-07-08 | 1987-07-08 | Production of superconducting ceramic |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6414157A (en) |
-
1987
- 1987-07-08 JP JP62170395A patent/JPS6414157A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6414157A (en) | 1989-01-18 |
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