JPH0574547B2 - - Google Patents
Info
- Publication number
- JPH0574547B2 JPH0574547B2 JP62170396A JP17039687A JPH0574547B2 JP H0574547 B2 JPH0574547 B2 JP H0574547B2 JP 62170396 A JP62170396 A JP 62170396A JP 17039687 A JP17039687 A JP 17039687A JP H0574547 B2 JPH0574547 B2 JP H0574547B2
- Authority
- JP
- Japan
- Prior art keywords
- phase
- orthorhombic
- superconducting
- tetragonal
- temperature
- 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 23
- 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 claims description 22
- 239000013078 crystal Substances 0.000 claims description 19
- 239000000919 ceramic Substances 0.000 claims description 13
- 238000005245 sintering Methods 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 239000002994 raw material Substances 0.000 claims description 7
- 238000001354 calcination Methods 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 230000015572 biosynthetic process Effects 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 description 11
- 239000000463 material Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 238000000034 method Methods 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 238000007731 hot pressing Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 230000007704 transition 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
- 239000000956 alloy Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001513 hot isostatic 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
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000007858 starting material Substances 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−Cu系超電導セラミツクスの製造方
法に関する。
背景技術
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、
たとえば、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
の正方晶組織では超電導相を示さず、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、従来の粉末冶金法による焼成法では、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、
仮焼原料粉末としてBaCO3、Y2O3、CuOを所
要量混合後、大気中で600℃〜900℃に１時間以上
の仮焼を行つた後、斜方晶組織と正方晶組織との
混合組織からなる粒度3μm以下のYBa2Cu3O7-x
組成（ｘ＝０〜0.25）の原料粉末を、
１気圧〜10気圧の100vol％O2雰囲気中で
600℃〜900℃に加熱して、正方晶組織に変化さ
せた後、
100vol％O2雰囲気中で、斜方晶の安定生成領
域（550℃〜600℃）の温度、かつ
200Kg／cm2〜2000Kg／cm2の圧力にて加圧焼結す
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粉である
BaCO3、Y2O3、CuOを所要量混合した後、大気
中で600℃〜900℃、１時間以上の仮焼を行なう。
さらに、微粉砕して、斜方晶の低温安定相と正
方晶の高温不安定相の混合組織からなる粒度3μm
以下の仮焼粉末を得る。
この仮焼粉末を、１気圧〜10気圧の100vol％
O2雰囲気中で、600℃〜900℃に２時間〜20時間
加熱して、組織を正方晶組織に変化させる。
その後、斜方晶の低温安定相の生成される温
度、すなわち550℃〜600℃の温度範囲で、
100vol％O2雰囲気中、加圧条件
200Kg／cm2〜2000Kg／cm2の圧力にて加圧焼結す
ることにより、焼結体全体が斜方晶組織からなる
超電導セラミツクスを得る。
この発明において、加圧焼結方法は熱間静水圧
プレス法でもよく、またホツトプレス法でもよ
い。
限定理由
この発明において、仮焼原料粉末の粒度を3μm
以下に限定した理由は、粒度3μmを超えると酸素
が内部まで拡散せず、焼結時に正方晶が一部残存
し好ましくないためである。
また、斜方晶組織と正方晶組織との混合組織か
らなる仮焼粉末を、正方晶組織へ変化させるため
の条件として、１気圧〜10気圧の100vol％O2雰
囲気を用いる理由は、１気圧未満では他の化合物
相が生成し、10気圧を超えると装置が大型化する
ばかりで、効果の増大がないので好ましくなく、
また、O2雰囲気は、少量のBaCO3の生成を防ぐ
理由から100vol％O2にする必要がある。
また、加熱条件としては、600℃未満では正方
晶に相転移せず、900℃を超えると焼結が進行す
るので好ましくない。
この発明における加圧焼結条件は以下のとおり
である。
加圧焼結における雰囲気は、斜方晶のみを生成
させる理由から100vol％O2雰囲気にする必要が
ある。
また、加熱条件は、550℃未満では焼結が進行
し難く、600℃を超えると正方晶（非超電導相）
が副生するため、550℃〜600℃にする必要があ
る。
また、加圧条件は、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、2000
Kg／cm2を超えると装置本体が実用的でないため、
200Kg／cm2〜2000Kg／cm2に限定する。
発明の効果
この発明は、配合原料粉末の仮焼粉末が製造の
容易な斜方晶（超電導相）と正方晶（非超電導
相）との混合相であるが、一旦、正方晶のみの組
織に変化させたのち、配合原料粉末を超電導相が
安定して生成する温度領域で加圧焼結するため、
正方晶が全て斜方晶に変態し、かつ超電導相を有
する斜方晶が非超電導相の正方晶へ変態すること
が抑制されるため、焼結体全体が均質な超電導相
からなり、高い臨界温度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5μm以下のBaCO3、Y2
O3、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。
その後、大気中で900℃、20時間の仮焼し、さ
らに、微粉砕して得られた粒度3μm以下の仮焼粉
を得た。
仮焼粉をＸ線回析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と正方晶からなる
高温不安定相の混合組成よりなることが分つた。
次に、前記仮焼粉を２気圧の100vol％O2雰囲
気中で、850℃に20時間保持させて、組織を正方
晶組織に変化させた後、粒度1μm以下に微粉砕し
た。
この微粉砕粉を、材質SiCからなる寸法径20mm
φ×高さ30mm寸法のダイスを用いて、100vol％
O2雰囲気中で、温度600℃、圧力500Kg／cm2にて
10時間保持して、ホツトプレスを行つた後、炉冷
して、寸法径20mmφ×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90°K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
5μm以下のBaCO3、Y2O3、CuO粉末を混合後、
実施例と同一条件にて仮焼後、微粉砕して粒度
3μm以下の仮焼粉を得た。仮焼粉の結晶構造は実
施例と同じ斜方晶からなる低温安定相と正方晶か
らなる高温不安定相の混合組織であつた。
前記仮焼粉を実施例と同一条件にて熱処理し
て、組織を正方晶組織に変化させた後、粒度1μm
以下に微粉砕後、実施例と同一の寸法、材質のダ
イス内に前記微粉砕粉を装入後、第１表の如き加
圧焼結条件にて、加圧焼結して、焼結体を得た。
得られた焼結体の組織を調査した結果を第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 -Cu-based superconducting ceramics. Background technology Conventionally, superconducting materials include Nb-Ti, Nb-Sn,
Alloy materials such as Nb 3 Sn or intermetallic compound materials 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 firing method using conventional 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 orthorhombic crystal formation by mixing required amounts of BaCO 3 , Y 2 O 3 , and CuO as calcined raw material powders, and then calcining the mixture at 600°C to 900°C for more than 1 hour in the air. YBa 2 Cu 3 O 7-x with a grain size of 3 μm or less, consisting of a mixed structure of a tetragonal structure and a tetragonal structure
Raw material powder with the composition (x = 0 to 0.25) is heated to 600℃ to 900℃ in a 100vol% O 2 atmosphere of 1 atm to 10 atm to change it to a tetragonal structure, and then heated in a 100vol% O 2 atmosphere. A method for producing superconducting ceramics characterized by pressure sintering at a temperature in the stable orthorhombic formation region (550°C to 600°C) and a pressure of 200Kg/cm 2 to 2000Kg/cm 2 . be. Structure of the Invention To explain this invention in detail, first, BaO−Y 2 O 3 −
It is a starting material powder for CuO-based superconducting ceramics.
After mixing the required amounts of BaCO 3 , Y 2 O 3 and CuO, calcination is performed in the air at 600° C. to 900° C. for 1 hour or more. Furthermore, it is finely pulverized to a particle size of 3 μm, consisting of a mixed structure of an orthorhombic low-temperature stable phase and a tetragonal high-temperature unstable phase.
The following calcined powder is obtained. This calcined powder is heated to 100 vol% at 1 atm to 10 atm.
The structure is changed to a tetragonal structure by heating at 600° C. to 900° C. for 2 hours to 20 hours in an O 2 atmosphere. Thereafter, it was heated in a 100 vol% O 2 atmosphere at a pressure of 200 Kg/cm 2 to 2000 Kg/cm 2 at a temperature at which a low-temperature stable orthorhombic phase is produced, that is, a temperature range of 550°C to 600°C. By pressure sintering, a superconducting ceramic whose entire sintered body has an orthorhombic crystal structure is obtained. In this invention, the pressure sintering method may be 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 for limiting the particle size to the following is that if the particle size exceeds 3 μm, oxygen will not diffuse into the interior, and some tetragonal crystals will remain during sintering, which is not preferable. In addition, the reason why a 100vol% O 2 atmosphere of 1 atm to 10 atm is used as a condition for changing the calcined powder consisting of a mixed structure of orthorhombic and tetragonal to a tetragonal structure is 1 atm. If the pressure is less than 10 atm, other compound phases will be formed, and if it exceeds 10 atm, the device will simply become larger and the effect will not increase, which is not preferable.
Furthermore, the O 2 atmosphere needs to be 100 vol% O 2 to prevent the formation of a small amount of BaCO 3 . Further, as for heating conditions, if it is less than 600°C, no phase transition to tetragonal crystal occurs, and if it exceeds 900°C, sintering will proceed, which is not preferable. The pressure sintering conditions in this invention are as follows. The atmosphere during pressure sintering needs to be a 100 vol% O 2 atmosphere in order to generate only orthorhombic crystals. In addition, when the heating conditions are lower than 550℃, sintering is difficult to proceed, and when the heating condition is higher than 600℃, the tetragonal (non-superconducting phase) occurs.
is produced as a by-product, so the temperature must be between 550℃ and 600℃. In addition, if the pressure condition is less than 200 kg/cm 2 , the powder will not become densified and the effect of pressure sintering will not be recognized.
If the weight exceeds Kg/ cm2 , the device itself becomes impractical.
Limited to 200Kg/cm 2 to 2000Kg/cm 2 . Effects of the Invention In this invention, although the calcined powder of the blended raw material powder is a mixed phase of orthorhombic crystals (superconducting phase) and tetragonal crystals (non-superconducting phase) that are easy to manufacture, After this change, the blended raw material powder is pressure sintered in a temperature range where the superconducting phase is stably generated.
All of the tetragonal crystals are transformed into orthorhombic crystals, and the transformation of orthorhombic crystals with a superconducting phase to tetragonal crystals with a non-superconducting phase is suppressed, so the entire sintered body consists of a homogeneous superconducting phase and has a high criticality. A superconducting material having a temperature Jc can be obtained. Example: BaCO 3 , Y 2 with a purity of 99.9% or more and a particle size of 5 μm or less
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. Thereafter, it was calcined in the air at 900°C for 20 hours, and then finely pulverized to obtain calcined powder with a particle size of 3 μm or less. As a result of examining the crystal structure of the calcined powder using X-ray diffraction, it was found that it consisted of a mixed composition of a low-temperature stable phase consisting of orthorhombic crystals and a high-temperature unstable phase consisting of tetragonal crystals. Next, the calcined powder was held at 850° C. for 20 hours in a 100 vol% O 2 atmosphere at 2 atmospheres to change its structure to a tetragonal structure, and then it was pulverized to a particle size of 1 μm or less. This finely pulverized powder is made of SiC material with a diameter of 20 mm.
100vol% using a die with dimensions of φ x height 30mm
In an O 2 atmosphere, at a temperature of 600℃ and a pressure of 500Kg/cm 2
After holding for 10 hours and hot pressing, it was cooled in a furnace to obtain a sintered body with dimensions of 20 mm in diameter and 6 mm in height. 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
A superconducting ceramic exhibiting the Meissner effect at 90°K was obtained. (Comparative example) Particle size 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 of 5 μm or less,
After calcining under the same conditions as in the example, finely pulverize to determine the particle size.
A calcined powder of 3 μm or less was obtained. The crystal structure of the calcined powder was a mixed structure of a low-temperature stable phase consisting of orthorhombic crystals and a high-temperature unstable phase consisting of tetragonal crystals, as in the examples. The calcined powder was heat-treated under the same conditions as in the example to change the structure to a tetragonal structure, and then the particle size was 1 μm.
After finely pulverizing, the finely pulverized powder was charged into a die having the same dimensions and material as in the example, and was then pressure sintered under the pressure sintering conditions shown in Table 1 to form a sintered compact. I got it. Table 2 shows the results of investigating the structure of the obtained sintered body.
【表】【table】
Claims (1)
所要量混合後、大気中で600℃〜900℃に１時間以
上の仮焼を行つた後、斜方晶組織と正方晶組織と
の混合組織からなる粒度3μm以下のYBa2Cu3
O7-x組成の原料粉末を、１気圧〜10気圧の100vol
％O2雰囲気中で600℃〜900℃に加熱して、正方
晶組織に変化させた後、100vol％O2雰囲気中で、
斜方晶の安定生成領域温度、かつ200Kg／cm2〜
2000Kg／cm2の圧力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。1. After mixing the required amounts of BaCO 3 , Y 2 O 3 , and CuO as raw material powder for calcination, calcination is performed at 600°C to 900°C in the air for 1 hour or more, and then an orthorhombic structure and a tetragonal structure are formed. YBa 2 Cu 3 with a particle size of 3 μm or less consisting of a mixed structure of
Raw material powder with O 7-x composition is heated to 100 vol at 1 atm to 10 atm.
After heating to 600℃~900℃ in % O2 atmosphere to change to tetragonal structure, in 100vol% O2 atmosphere,
Temperature in the stable formation region of orthorhombic crystals and 200Kg/cm 2 ~
A method for producing superconducting ceramics characterized by pressure sintering at a pressure of 2000 kg/cm 2 .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62170396A JPS6414158A (en) | 1987-07-08 | 1987-07-08 | Production of superconducting ceramic |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62170396A JPS6414158A (en) | 1987-07-08 | 1987-07-08 | Production of superconducting ceramic |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6414158A JPS6414158A (en) | 1989-01-18 |
| JPH0574547B2 true JPH0574547B2 (en) | 1993-10-18 |
Family
ID=15904152
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62170396A Granted JPS6414158A (en) | 1987-07-08 | 1987-07-08 | Production of superconducting ceramic |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6414158A (en) |
-
1987
- 1987-07-08 JP JP62170396A patent/JPS6414158A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6414158A (en) | 1989-01-18 |
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