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[in Japanese]
1990 Volume 37 Issue 5 Pages
596
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL
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Yutaka Arakida
1990 Volume 37 Issue 5 Pages
597-600
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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More recently, powder injection molding process has become recognized as a practical mass production process applicable to the manufacturing of ralatively small, highly configured components in powder materials, such as ceramics, metals and cermets. In this report, aspects relating to technologies and process requirements, and a trend of the development on their process techniques are described.
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Yoshisato Kiyota, Hiroshi Ohtsubo
1990 Volume 37 Issue 5 Pages
601-604
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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Metal injection molded Fe-Co alloys with magnetic properties comparable to those of wrought materials have been developed. Sintering behaviors of Fe-50%Co compacts prepared from a carbonyl iron powder and a reduced cobalt powder are quite similar to those of a carbonyl iron. For the production of metal injection molded Fe-50%Co alloys, sintering in the alpha phase region is efficient to densification, while sintering in the gamma phase region is effective to pore spheroidization and grain growth. The alloys sintered in the alpha phase region and subsequently in the gamma phase region attain high magnetic flux density (B
20) of more than 22kG, low coercive force equal to 1.0 Oe and high maximun permeability of more than 8000.
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Yasunari Kaneko, Kei Ameyama, Shigeya Sakaguchi
1990 Volume 37 Issue 5 Pages
605
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Commercially pure titaniu., Co and Al-V alloy powders were mixed to produce the Ti-5wt%Co and Ti-6 wt%Al-4wt%V powders. The powder was processed by the injection molding.Acrylate, atactic-polypropyren e and wax were used as the binder.The carbon and oxygen contents in the sintered specimens were lea s in the case of the two step debinding process compared to that of the conventional debinding process. Addition of Co and Al-V alloy powder promoted the formation of the fine (α+β) two phase structure.The density of specimens sintered at 1300°C in vaccum were 95%.The bending strength of Ti-6Al-4V powder specimen was 1300MPa.
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Yasunari Kaneko
1990 Volume 37 Issue 5 Pages
606-607
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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The slip casting of Cu and SUS316L fine powders was made by using the triethanol alginate as the binder material. The slip containing 15.4-18.2mass% water and 0.15-0.18 ?? ass% triethanol alginate had the good flowability. The green relative density of Cu and SUS316L were 52 and 51%. By sintering at 970°C in H
2 gas for lhr, Cu green bodys were densified to 96% and over. By sintering at 1300°C in vaccum for 1hr, SUS316L green bodys were densified 96% and over.Speci.ens sintered at 1300°C showed the ultimate tensile strength of 500MPa and the elongation of 35%.
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Junjiro Takakawa
1990 Volume 37 Issue 5 Pages
608-611
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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The debinding process and the relationship between the binder removal(%)and the sinterability of injection molded compacts were investigated. Two types of SUS316L powders having different particle sizes were used. The main results obtained were as follows.
1) The binder removal(%) of an injection molded compact was proportional to its specific surface area when debound under the same conditions in the temperature range where debinding was accomplished mainly by thermal decomposition.
2) The relative density of sintered compact increased with increasing the binder removal(%) when sintered at 1270°C. On the other hand, sintered at 1310°C, high density(>94%) was achieved even in the compacts of low binder removal.
3) The sintered structure of the compacts of very low binder removal(%) showed remarkable growth of crystal grains and residual pores, and many precipitates of carbide near the boundaries.
4) The desirable binder removal (%) in the debinding process was estimated at 90-94%, by considering sintering behaviors of the compacts.
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Yoshimitsu Kankawa, Katsuyoshi Saitou, Yasunari Kaneko
1990 Volume 37 Issue 5 Pages
612-615
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Sintering in CaHPO4 on injection molding of hydroxylapatite utilizing solid phase reaction method was studied. Rod like test pieces were produced by the injection molding with phosphoric acid(54.5wt%), calcium carbonate(26.8wt%) and the several organic binders(18.7wt%).
After the binder extraction process, the test pieces were sintered under the following conditions :
(A)in an atmospher of air ;(B)in the CaHPO4. The sintered test piece (A) consists of hydroxylapatite, whereas the top surface of sintered test piece (B) consists of β-TCP. From the above results, the porosity of the sintered test piece (B) was lower than that of the sintered test piece (A), and the compressive strength of the sintered test piece (B) was higher than that of the sintered test piece (A).
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Hiroki Miyamoto
1990 Volume 37 Issue 5 Pages
616-620
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Slip casting of Si
3N
4 powder in plaster mold was carried out. PVA binder gives the green body plasticity as well as strength. Mean flexural strength of sintered body of silicon nitride was 83.5 kgf/mm
2 and Weibull constant was 21.3. In order to improve productivity of slip casting method, a high pressure casting apparatus, which enables to apply pressures up to 200 kgf/cm
2 for slurry, was devised. The casting time of alumina compact of 10×50×70(mm) was shortened from 60 min of pressureless casting to 6 min of pressure casting with 200 kgf/cm
2. The green compact obtained by pressure casting higher than 100 kgf/cm
2 scarcely shows shrinkage during drying.
Alumina and silicon nitride were prepared by low pressure injection molding. Weibull plot of flexural strength gave mean strength of 48 kgf/mm
2 with Weibull constant of 14.5 for alumina and mean strength of 91.3 kgf/mm
2 with Weibull constant of 11.9 for silicon nitride, respectively. A transparent mold with a window of a strengthened glass was devised. This mold enables to visualize the dynamic flow of the slurry through the glass window by VTR. Using this mold, the best condition of homogeneous molding without turbulence of injecting slurry was easily determined.
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[in Japanese]
1990 Volume 37 Issue 5 Pages
622
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Yong Ho Park, Hitoshi Hashimoto, Ryuzo Watanabe
1990 Volume 37 Issue 5 Pages
623-627
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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An effect of milling ball size on mechanical alloying process of Ti-Cu was investigated during vibratory ball milling of a mixture of elemental Ti and Cu powders. It was found that fine amorphous powder was produced and that the change in morphology, X-ray diffraction pattern, hardness, crystallization temperature and enthalpy of the powder particles during milling depended on the milling ball size. The changes in the crystallization temperature and enthalpy seemed to be caused by the compositional change of amorphous alloy during milling.
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Kazutaka Asabe, Mutuo Nakanishi
1990 Volume 37 Issue 5 Pages
628-631
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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Alloying. Alloying process in mechanical alloying (MA) and reaction behavior in heating of Ni-Cu solid solution were analized. Alloying was occured in lower temperature and shorter time in accordance with the progress of MA, ie. the state of mixing Ni and Cu became higher. Resultant phase in MA and heat treatment was the same as the phase occured only in HA, but activation energy tended to decrease as the increasing time of MA. We concluded that non-equillibrium mixing phases that cannot be occured in conventional way can be formed in combination with MA and beat treatment.
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Yasuhisa Tanaka, Teruo Ohasi
1990 Volume 37 Issue 5 Pages
632-635
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Copper-lead alloys are widely used for making sliding bearings. When copper is alloyed with lead, lead acts as a kind of inclusion due to its immiscibility. It is safely presumed, then, that if such inclusions are more finely distributed, the load capacity of bearing materials is increased. In the present study a high-energy type of mechanical alloying method which is recently established for making amorphous alloys was used to give copper-lead alloys an even finer lead distribution. Mechanically ground powders of copper-lead alloy performed for 50hr. in particular shows an evenly distributed fine structure in which the individual lead particles are hardly distinguishable. An X-ray diffraction analysis revealed, however, that the extent of alloying had not reached yet a level that would cause the substitution of copper and lead atoms with each other. Two kind of the sintered materials were made, the one from MG powders and the other from atomized alloyed powders under the same sintering conditions. Comparison between their sintered structures shows that the former structure is finer than the latter one.
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Woo-Yeong Lim, Moritaka Hida, Akira Sakakibara, Yoshito Takemoto, Hiro ...
1990 Volume 37 Issue 5 Pages
636-639
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Mixture of Ti and Mo powders was mechanically alloyed to obtain β-type Ti-20mass-%Mo alloy. The mechanism of mechanical alloying(MA) of Ti-20mass%Mo and microstructure of its product were investigated by X-ray diffraction, XAFS and TEM. X-ray diffraction profile showed that complete alloying was attained by the 36ks-MA, but incompleteness was revealed by the analysis of XAFS. According to the result of XAFS, 144ks-MA was needed to accomplish alloying. The radial structural parameters of j-th shell, R
j , N
j and σ
j are obtained by curve fitting method on a two-shell, double Mo-Mo and Mo-Ti pairs. Nearest neighbor bond length(R
j ) decreased with the time of MA. From the observation of TEM, it was revealed that mechanically alloyed particle was composed of small domains with different lattice images in direction, like subgrains. Deformation of the lattice image was also recognized for the MA specimen.
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Nobuo Asahi, Osami Haruyam
1990 Volume 37 Issue 5 Pages
640-643
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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Amorphous Ni
xZr
100-x alloy powders (x=28, 33, 40, 45, 50, 65, 70) were synthesized by MA from crystalline powders of the elements using high-energy ball milling in an argon atmosphere. The alloying and amorphization process was investigated by X-ray diffractometry and differential scanning calorimetry.
X-ray diffraction profiles taken as a function of milling time showed that, at the initial stage of MA, amorphization proceeded rapidly, that is, the preferential diffusion of Ni through Zr occurred rapidly and then proceeded slowly with increas-ing milling time. The amorphization by MA is found to depend on a large negative heat of mixing as the driving force of the diffusion. The radial-distribution functions, determined by X-ray diffractometry, are comparable to those measured for mechanical alloyed and liquid quenched amorphous Ni-Zr alloys of the same composition.
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Toshiharu Fukunaga, Yoshiya Homma, Kenji Suzuki
1990 Volume 37 Issue 5 Pages
644-647
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Partial Ni-Ni atomic structures were directly observed by neutron diffraction in the amorphization process of Ni
100-xV
x powders during the mechanical alloying(MA).
The partial radial distribution function RDF
NiNi(r) shows that distribution peaks of the fcc-Ni crystal gradually broaden with increasing MA time. The peaks of the 2nd and 5th Ni-Ni neighbor positions observed within 7 A distance dramatically rapidly decrease and disappear almost completely after 400h milling. This means that a tetrahedral unit characteristic of an amorphous structure increases at the expense of the octahedral unit, because the 2nd and 5th Ni-Ni neighbor contribute exclusively to the formation of the octahedral units in fcc structure.
The coordination number of Ni atoms around a Ni atom calculated from the area under the 1st peak decreases with increasing V concentration. From this concentration dependence, it can be concluded that the chemical short range order in the Ni-V amorphous alloy obtained by MA is analogous to that of the σ phase existing as a stable phase in the range 50-70at%V.
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Mitsuhiro Mori, Kazuya Inou, Toshiharu Fukunaga, Uichiro Mizutani
1990 Volume 37 Issue 5 Pages
648-651
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Cu and V atoms are immiscible even in the liquid state and its alloy system is characterized by a positive heat of mixing. The mixture of elemental Cu and V powders was compulsively mixed by mecahnical alloying(MA). The mixing at an atomic level and amorphization process during MA were studied by neutron diffraction and DSC measurements.
A sharp peak characteristic of the crystallization of an amorphous phase is not observed in the DSC spectrum even after 120 hours of milling. However, the total energy stored be MA process increased with MA time and the value after 120 hours of milling tended to saturate at 14.3 kJ/mol.
Some of Bragg peaks of fcc-Cu crystal observed in S(Q) before MA quickly diminish and others become broadened with increasing milling time. A halo pattern dominates after 60 hours milling, though the 1st peak remains rather sharp in comparison with that of a typical amorphous alloy. The distribution peaks of fcc-Cu crytal in RDF(r) broaden and approach gradually to those
characteristic of an amorphous state. Especially, the peaks of 2nd and 5th Cu-Cu neighbor positions observed within 7 A distance drastically decrease and eventually disappear.
These results may mean that the amorphization of Cu-V powders by MA gradually but eventually proceeds.
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Nobuya Iwamoto, Shinya Uesaka
1990 Volume 37 Issue 5 Pages
652-655
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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Nickel and molybdenum form a variety of compounds with silicon. These silicides posess many interesting properties, such as low density, good oxidation resistance and good electronic property. Their narrow compositional range and high melting points, nevertheless, make the processing by conventional methods difficult. In this study, the formation of silicides was attempted by the mechanical alloying (MA) method. The MA behavior of Ni-Si and Mo-Si systems was examined at atomic ratios corresponding to stoichiometric compositions of respective silicides. It was observed that silicides equivalent to the ratios of mixed element powders, were produced in the MA process. In the MA behavior of Mo
33Si
67, αMOSi
2 of the low temperature phase and βMoSi
2 of the high temperature phase were formed; further, in more MA, they resulted in amorphization.
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Teruo Takahashi, Hiroshi Daichoh
1990 Volume 37 Issue 5 Pages
656-659
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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Mechanical alloying was carried out using pure iron, pure niobium and graphite powders. The very fine homogeneous alloy powder was obtained after the mechanical alloying for 144.0 ks. The very fine NbC particles were precipitated in this alloy powder by the heat-treatment in the temperature range of 873-1273 K. The mean particle size of the NbC was decreased with decreasing the heat-treatment temperature, resulting in about 8.5 nm by the heat-treatment at 873 K for 3.6 ks. The mean particle size of the NbC precipitated by the present method was finer than that of the NbC powder using as starting materials crushed and dispersed by mechanical alloying. The micro-Vickers hardness values were very high in the lower temperature range, however they were decreased with increasing the heat-treatment temperature.
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Takeo Tanaka, Saburo Nasu, Susumu Imaoka, Keiichi Ishihara, Hideo Shin ...
1990 Volume 37 Issue 5 Pages
660-664
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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Mechanical alloying (MA) of iron and graphite powders has been performed using a conventional ball-mill. MA process of Fe
1-xCx (x=0.17-0.90) powders has been studied by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, 57Fe Mössbauer spectroscopy and differential scanning calorimetry.
Results from X-ray diffraction and 57Fe Mbssbauer measurement suggest the formation of amorphous phase in powders ball-milled for about 200 hours. After subsequently long milling periods like 1000 hours, the formation of metastable carbides of Fe
3C and Fe
7C
3 has been detected for the powders of x=0.17-0.25 and x=0.29-0.70. Formation of super-paramagnetic Fe-C particles at room temperature has been detected by Mössbauer spectroscopy for the powders having a higher carbon content like x=0.90.
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Atsushi Kakitsuji, Masaaki Tanihara, Hiroki Miyamoto, Yuzuru Takahashi ...
1990 Volume 37 Issue 5 Pages
665-669
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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TiAl intermetallic compounds with composition range Ti-45 to 55 at.%Al were synthesized from elemental powder by HIP-reaction sintering. Namely, mixed powder compacts of Ti and Al were capsuled in pyrex glass tube and HIP treated at 1073 to 1573 K under a pressure of 196 MPa. Under HIP treatment temperature higher than 1523K, fully densified, sintered spacemen with a lamellar structure, typical for TiAl intermetallic compound, was obtained. It was concluded by thermal analysis and X-ray diffraction that at first several compounds of Ti-Al system, like TiAl, Ti
3Al, TiAl
2 and TiAl
3, were synthesized by self-propageting reaction and densified by subsequent hot isostatic pressure and transformed to TiAl/Ti
3Al lamellar structure.
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P.Hideo Shingu, Keiichi N. Ishihara
1990 Volume 37 Issue 5 Pages
670-673
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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A pseudo HIP (PHIP) process was developed to synthesize the compound TiAl, starting from the swaged compact of homogeneously mixed elemental Ti and Al powders. The PHIP process was performed by the use of silica sand contained in a stainless steel pressure resistant vessel. A heating coil was set in the sand so that the sample could be heated up to 1143K under a pseudo isostatic pressure of 50MPa generated by the use of a hydraulic press. TiAl compound samples of full density with compressive strength of 1.8GPa with plastic strain of 30% were obtained.
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[in Japanese]
1990 Volume 37 Issue 5 Pages
676
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Ken-ichi Sato, Hidehito Mukai, Takeshi Hikata, Munetugu Ueyama, Masayu ...
1990 Volume 37 Issue 5 Pages
677-679
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Among the high-temperature superconductors, Bi-based superconductors have critical temperature exceeding 100K and resources used for them are relatively widely available since they contain no rare-earth elements. The autors have made attempts to improve the critical current density of silver-sheathed Bi-based superconducting wires, and successfully achieved a superconductor with critical current densities as high as 3.2×10
4A/cm
2 in a zero magnetic field, 2.3×10
4A/cm
2 at 0.1 T and 6×10 3A/cm
2 at 1 T at 77K. They also succeeded to make long conductors and strain-resistant multi-filamentally wires.
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Eiji Muromachi
1990 Volume 37 Issue 5 Pages
680-683
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Oxygen deficiency in YBa
2(Cu
1-xMx)
3O
y (M=Al, Fe, Co, Ga) system is discussed. Superconductivity of the impurity-doped system is much more sensitive to the oxygen defects compared with pure YBa
2Cu
3 Oy.It is suggested that this enhancement of oxygen-deficiency effect is associated with the oxygen disordering within the Cu1-0 layer. Monte Carlo simulation of oxygen configuration within the Cu1-0 layer of the impurity-doped system is presented.
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Seiichiro Kashu, Yasuyuki Matsuzaki, Makoto Kaitou, Keisaku Hatanaka, ...
1990 Volume 37 Issue 5 Pages
684-687
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Superconductive thick film of BPSCCO was formed on MgO substrate by gas deposition using fine powder of BPSCCO having diameter less than 1μm. After heat treatment at 770°C for 10hr in air atmosphere by use of electric furnace, Tc(end) was found 105K.
In this study, as deposited BPSCCO thick film, which was moved at the speed of 1mm/min, was heated by infrared heating spot. After heating the surface of MgO substrate at the temperature of 920°C by infrared spot, Tc(end) of BPSCCO thick film was found 85K.
It is desired to select more suitable heating condition. This heat treatment is useful for continuous manufacturing process of long superconductive thick film.
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Yoshimitu Ogawa, Junichi Ishiai, Yutaka Mitsune, Yuzo Tasaki, Shuji Yo ...
1990 Volume 37 Issue 5 Pages
688-691
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Superconductive thick film was prepared by the screen printing method on MgO polycrystalline substrate. Textured orientation with c-axis of the superconductive phase was shown in the XRD patterns. The paste was prepared by calcined powder of (Bi
1-
xPb
x)
2Sr
2Ca
2Cu
3Oy (x=0.2, 0.3, 0.4). In the film from the x=0.4 paste, high Tc and high Jc were obtained by short sintering time irrespective of an impurity phase growth of Ca
2PbO
4, etc. A CIP after printing and subsequent solvents drying was applied before sintering. The CIP improved strongly the textured orientation with c-axis and, therefore, the quality of the thick films.
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Keizou Tsukamoto, Mamoru Ishii, Hiromasa Shimojima, Chitake Yamagishi, ...
1990 Volume 37 Issue 5 Pages
692-695
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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A superconducting tube has been developed for a magnetic shielding. This tube was composed of 22 pieces of Bi(Pb)-Sr-Ca-Cu-O ring disks prepared by a doctor blade method. As the magnetic field was applied parallel to the axis of the tube, the magnetic flux density was shielded up to 21 gauss by the tube. Then, the decay of the trapped magnetic flux density for the tube showed logarithmic dependence in time. The activation energy estimated from Anderson's flux creep model was about 0.3eV.
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Hiroshi Maiwa, Kyou-ichi Asaka, Masahiro Kato, Noboru Ichinose
1990 Volume 37 Issue 5 Pages
696-700
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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Superconducting thin films of Bi-Pb-Sr-Ca-Cu-O system were prepared on single crystal MgO(100) substrates by rf magnetron sputtering. The films deposited below 450°C were amorphous and insulating. These films were crystallized when annealed at temperature 830-850°C. The superconducting properties and phases were dependent on target compositions, substrate temperatures and annealing conditions. Impurity phases such as Ca
2PbO
4, (Ca, Sr)
3Cu
5O
x gave bad effects on the superconducting properties of the films. Films sputtered from Bi
2.7Pb
2Sr
2Ca
2Cu
3.2O
2 target at 400°C and post-annealed at 840°C for 3 hours in air showed Tc(R=0)=108K and Jc(77K, zero magnetic field)=7010A/cm
2.
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Keiichi Tanabe, Youichi Enomoto, Akihiko Yamaji
1990 Volume 37 Issue 5 Pages
701-704
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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The electrical responses to infrared radiation of La
2-
xSr
xCuO
y(100) and YBa
2Cu
3O
y(103) epitaxial films with various kinds of crsystal orientation are studied using modulated laser light.
These films show apparently nonbolometric responses at temperatures below the transition regions which are strongly dependent on the bias current. The difference in the observed responsivity between these high-Tc materials and BaPb
1-
xBi
xO
3 can be explained on the basis of nonequilibrium superconductivity.
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Satoru Ohno, Hideo Hkuyama, Kazuhiro Honma, Masaya Ozawa
1990 Volume 37 Issue 5 Pages
705-708
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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In order to synthesis the superconductive Bi-Sr-Ca-Cu-O ceramics, ultrafine powders were prepared by arc-melting, evaporation and deposition of Bi, Sr, Ca and Cu metals in the 50%Hz-Ar atmosphere at 0.1 MPa pressure ("hydrogen plasma-metal" reaction). Crystal structures of ultrafine powders obtained from Bi and Cu metals were found to be metallic phase of Bi and Cu. but in the case of Sr and Ca metals were found to be hydroxide compounds [Sr(OH)
2 and Ca(OH)
2] of Sr and Ca. The specific surface area of Bi, Sr(OH)
2, Ca(OH)
2 and Cu ultrafine powders determined by BET method were 2.1, 20.0, 25.5 and 7.8 m
2/g, respectively.
The sintering and superconducting properties of Bi-Sr-Ca-Cu-O system (Bi:Sr:Ca:Cu = 4:3:3:6) were investigated by using a mixture of above ultrafine powders. DTA measurements indicated that the most favorable temperature range for solid-state sintering in air was between 830°C and 870°C, regardless of the mixed powders was calcined or not. When the mixed powder is sintered at the above temperature range for 3-5 h, a great amount of low Tc phase (80K) is formed in the sintered specimen, but sintering longer than about 20 h caused a decrease in low Tc phase and formation of a small amount of high Tc phase (110 K). It is found that high Tc phase is formed effectively by resintering of a compact prepared from the specimen including a great amount of low Tc phase.
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Kohmei Halada, Hiroo Suga
1990 Volume 37 Issue 5 Pages
709-712
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Rapidly solidified superconductive glass ceramics (Bi:Sr:Ca:Cu=2:2:2:3) was produced by centrifugal atomization of molten oxides. Main product was spherodized glassy powder, while glassy flakes and ligaments were also obtained. The existence of superconductivity above 80K was observed after heat treatment. The state of crystallization was also investigated.
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Kazuhiko Majima, Hiroshi Nagai, Masaru Yokota, Ken Ohbayashi, Atushi T ...
1990 Volume 37 Issue 5 Pages
713-716
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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By using five differnt kinds of Bi
1.84Pb
0.34Sr
1.91Ca
2.03Cu
3.06Oy powders named No.0. No.1. No.2. No.7 and No.26 whose particle size is smaller in the sequence No.0-No.1-No.2-No.7-No.26. the influence of powder particle size on the grain size of the sintered specimen, the amount of high Tc phase and superconductive property has been investigated.
Contrary to the particle size of powders, the grain size of the sintered specimens became larger in the sequence No.0-No.1-No.2-No.7-No.26, and especially in No.7 and No.26 specimens, the abnormal grain growth was observed. Whereas both volume fraction of high Tc phase and Tc temperature of No.7 and No.26 specimens were much lower than those of No.0. No.2 and No.2. those peoperties were remarkably improved by regrinding, repressing and resintering.
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Katsuyoshi Hottta, Toshimasa Suzuki, Hidekazu Magome, Haruo Hirose
1990 Volume 37 Issue 5 Pages
717-720
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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We reported on the effect of water on Bi-Pb-Sr-Ca-Cu-O system superconductor in the preceding report. This article reports the changes in various superconductivity characteristics when the superconductor is soaked in such organic solvents as ethyl alcohol, methyl alcohol, acetone and toluene since the organic solvent is often used to remove contaminants on the surface. As for critical temperature, critical current density and maximum magnetization, each of these surface values showed the tendency to decrease with soaking time. Therefore, it should be noted that the organic solvents affect the superconductor characteristics to some extent if they were used to remove the contamination on the surface.
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Shuji Yoshizawa, Manabu Yanagawa, Shuetsu Haseyama, Koichi Kawazu, Yui ...
1990 Volume 37 Issue 5 Pages
721-724
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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TlBaCaCuO (2223) system high-Tc superconductor was prepared, whereupon the partcle size of raw material CuO was changed from several μm to superfine powder 150A. The superconductivity represented by Tc of 122K and Jc of 530A/cm
2 was much improved by the use of the superfine CuO powder. In the Bi system same effect of the particle size in CuO was observed. It is suggested from the result of XRD patterns and SEM images that, as the specific surface area of CuO particle is increased, the solid-phase reaction is accelertated inducing efficiently the high-Tc phase (2223) of superconductors.
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Shuetsu Haseyama, Koichi Kawazu, Shuji Yoshizawa
1990 Volume 37 Issue 5 Pages
725-728
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Influence of intermediate pressing after the initial sintering on the superconducting characteristics in the TlBaCaCuO system was studied. By this intermediate pressing and the subsequent sintering process, Jc was drastically increased. This result may be due to the increase of the bulk density. In the samples prepared by the cold isostatic pressing immediately after pelletizing by cold pressing, Jc was not increased.
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Yasunori Ikeda, Sinichi Shimomura, Zenji Hiroi, Hiroyuki Ito, Mikio Ta ...
1990 Volume 37 Issue 5 Pages
729-733
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Monophasic compositions of Bi
2-x+yPb
xSr
2-yCu
1+y/4O
z with O<x<0.5 and 0.1<y<O.5 were prepared in the BiO1.5-Pbo-SrO-CuO system. Pb-substitution tends to induce an orthorhombic distortion, though the critical Pb content increases as the Sr content decrease. The modulation has been found to completely disappear in a narrow range around the x>0.38 and y=0.125. The modulation free composition with z ?? 6.0 which could be prepared in an Ar stream of 1 atm but not in air, behaves as a superconductor with Tc-14K. An over-doped normal metal with x=0.35, y=0.125 and z=6.08 prepared in air also became superconducting below the same Tc on reduction to z ?? 6.02. From the composition dependence of the lattice distortion and the segregation reaction Pb has been suggested to occupy the Bi site when x is large and y is small but to occupy the Sr site when x is small and y is large.
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Jun Takada, Hitoshi Kitaguchi, Kiichi Oda, Yoshinari Miura, Hiromasa M ...
1990 Volume 37 Issue 5 Pages
734-738
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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Samples with various compositions, (Bi
1-aPb
a)
nSr
1.0Ca
1.0Cu
YO
X, where 0.16≤a≤0.36, n=1.1 and 1.2, and 1.50≤Y≤1.80, were heated in the temperature range from 840 to 860°C for 24 to 300h. Superconducting properties were studied by the measurements of the dc electrical resistivity as well as the ac magnetic susceptibility. Furthermore, lattice parameters were determined by the powder X-ray diffraction method. For the Pb-rich samples with a≥0.30 heated at 850°C for 120 to 192h, Tc(R=0) was found to be 116K and the Meissner effect was confirmed below 117K. The samples consist mainly of the high-Tc phase, although a small amount of Ca
2PbO
4 was observed. Tc(R=0) does not exceed 110K for a≤0.24, whereas the samples with a≥0.26 show Tc>110K. n and Y seem to have no influence upon Tc(R=0). In comparison with the lattice parameters in the Pb-poor samples (a=0.18 and 0.20) with Tc(R=0)-107K, the c axis was found to be longer in the Pb-rich samples with a=0.34 and 0.36 showing Tc(R=0) around 115K, though the a axis was unchanged. The expansion of the c axis may result from an increase in Pb content substituted in the high-Tc phase.
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Ryuji Sato, Nozomu Tamoto, Takayuki Kamatsu, Kazumasa Matusita, Tsutom ...
1990 Volume 37 Issue 5 Pages
739-742
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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We prepared superconducting Bi
1.6Pb
0.4-xTe
xSr2Ca
2Cu
3O
y ( x=0.1, 0.2, 0.3 and 0.4 ) glass-ceramics by the melt-quenching method and examined the effect of Te addition on the formation of high-T
c phase. It was found that the formation of the high-T
c phase was largely enhanced by the addition of a small amount (x=0.1 and 0.2 ) of Te element. In the Bi
1.6Te
0.4Sr
2Ca
2Cu
3O
y glass-ceramics, the main superconducting phase was the low-T
c phase. It was concluded that the lowering of the partial melting temperature at around 870°C caused by the coexistence of Pb and Te elements was very important for the formation of the high-T
c phase. The critical temperature of the sample ( x=0.2 ) annealed at 850°C for 100h was 103K.
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Hiroyuki Ito, Yasunori Ikeda, Zenji Hiroi, Mikio Takano, Yoshichika Ba ...
1990 Volume 37 Issue 5 Pages
743-746
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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The formation process of the 37Å (high-Tc) phase in the Bi-Pb-Sr-Ca-Cu-O system has been studied for a nominal composition Bi:Pb:Sr:Ca:Cu=0.9:0.2:1:1:1.6. From this composition we obtained the high-Tc phase crystallizing homogeneously in the Pb-induced modulation mode as reported previously. The solid phases formed after each firing treatment at above 795°C were identified, and the melting points of various combinations of these were measured. As a result, the lowest liquid formation temperature was found to be 825°C for a combination of the 24Å phase and Ca
2PbO
4. The liquid formation and formation of the Pb-substituted 30Å phase seems to be the initial step the formation of the 37Å phase.
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Kentaro Ohhashi, Setsuo Yada, Shigeharu Naka, Hideaki Itoh, Hitoshi Ki ...
1990 Volume 37 Issue 5 Pages
747-750
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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Specimens of (M
2.1) Sr
2.0Ca
2.0Cu
3.15O
y [(M
2.1)=(Bi
2.1-m-xPbmSbz) : O.1≤m≤0.5, O≤z≤0.4)] were sintered at 830, 840 or 850°C for 20hr after pre-treatment (20hr) and heating processes [I (20hr) and II (40hr) using envelope method] at the same temperature in air atmosphere. XRD patterns of specimens in each process and the resistance curves of sintered specimens were compared in order to find effects of Sb
2O
3 addition on the formation of high-Tc phase. The optimum heat treatment temperature was 840°C, which was a little lower than that of specimens without Sb
3+(z=0). And the range of treatment temperature forming high-Tc phase becomes narrower. In reaction diagram at 840 °C, it was found that high-Tc phase amounted to 70-80% for 20-40hr at the small content of Sb
3+:z≤0.2, although any single phase of high-Tc was not obtained. For specimen with Sb
3+ addition, the formation time of high-Tc phase was reduced very much in such composition range. A special case was observed in the specimens with Bi content of 1.75-1.80mol. In the case, Sb
3+ content incorporated with the ratio of Pb
2+: Sb
3+ larger than 8:2 brought a little increase of Tc rather than the decrease of Tc. The composition of the case, for example, is (M
2.1)=(Bi
1.8Pb
0.3-zSb
2) with z=0.05.
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Hiroshi Terada, Toshiyuki Ido, Saburo Muto
1990 Volume 37 Issue 5 Pages
751-754
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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The effect of Sb
2O
3 and MnO
2 addition on superconductivity of {Bi
0.8(Pb
1-xM
x)0.2}
2Sr
2Ca
2Cu
3O
y(M=Sb, Mn, O<x<0.3) has been studied.
The sample with the conposition x=0.075(M=Sb), which was prepared by heating at 850°C for 200hrs in air, has the highest Tc ?? 108K.
The substitution of Mn for Pb has been found to be useful for sintering.
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Hideki Yoshioka, Shinichi Kikkawa, Fumikazu Kanamaru, Yoshinari Miyamo ...
1990 Volume 37 Issue 5 Pages
755-758
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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Preparation and stabilities of Bi-Sr-Ca-Cu-O superconducting ceramics were studied under a pressure of 3GPa. Powder X-ray diffraction measurements showed that 2201-type phase was formed in the hot-pressed samples prepared both from mixed oxides, 2212-phase, 2223-phase. The hot-pressed samples showed high electrical resistivities and semiconducting bebaviour. Resistivity of the sample prepared from 2212-phase under conditions of 3GPa, 830°C, 6h dropped at 110K and 80K due to the remaining superconducting phases of the starting powder.
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Toshihiko Nishida, Susumu Shimano, Takashi Ohtsuka, Tomozo Nishikawa
1990 Volume 37 Issue 5 Pages
759-760
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Bi
2Sr
2CaCu
2O
x and Bi
1.8Pb
0.4Sr
2Ca
2Cu
20
x Powders Prepared by solid state reaction were encupsulated in the molds made of different kinds of metals. The molds were preheated at 820-840°C for 10 minutes and then press-forged under uniaxial compressive loads. The reducing effect of the metallic molds on superconducting character of the hot-forged ceramics was discussed in this note.
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Yoshio Sakka, Tetsuo Uchikoshi
1990 Volume 37 Issue 5 Pages
761-764
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Temperature programmed desorption (TPD) measurements in vacuum were examined for the oxide superconducting powders of synthesized high Tc Bi-Pb-Sr-Ca-Cu (Bi system) and YBa2Cu3O7-y (Y system). Oxygen desorption peak was observed around 470°C for the powder of Bi system after annealing at 400°C in oxygen atmosphere. Oxgen desorption peaks of Y system have been separated in four peaks. The desorption peak at 400-460°C is owing to the desorption of oxygen in "Cu(1) plane". Two desorption peaks at 650-670°C and at 790°C seem to originate from impurity phases. The desorption peak at 900°C arises from phase separation reaction.
To estimate sensitivity to water and carbon dioxide of the powders of Bi and Y system, TPD measurements were carried out after exposure to water vapor or carbon dioxide. TPD spectra of Bi system show no remarkable difference from those after annealing in oxygen atmosphere. However, two water desorption peaks were observed for the powders of Y system after exposure to water vapor at room temperature, which suggests that chemical reaction have proceeded.
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Yasuo Takeda, Kouichi Yoshikawa, Osamu Yamamoto, Mikio Takano, Yoshich ...
1990 Volume 37 Issue 5 Pages
765-768
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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The superconducting La
2-xNd
xCu0
4+z was obtained by being annealed under high oxygen pressure ranging from 0.2atm-60000atm. The oxygen content increases and orthorhombic distortion decreases versus oxygen pressure. For Nd non-doped La
2Cu0
4+z, the Tc value is almost pressure independent which is about 40K. The Nd doping decreases the Tc value but increases the conductivity in the normal conductive region. Nd doped samples show the strong dependence of Tc on the oxygen content. The fraction of superconductive phase drasticaly increases with Nd doping.
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Seiji Adachi, Hideaki Adachi, Kentaro Setsume
1990 Volume 37 Issue 5 Pages
769-771
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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Compositional region, in which the "0212" structure is stabilized, was investigated in a (La
1-ySr
y)
2 (Ca
1-xY
x)Cu
2O
z system. For ceramics at various x and y, crystal structure was examined by powder X-ray diffraction and electrical resistivity was measured by standard four-probe method. Almost single-phase ceramics were synthesized in the region of 1.0≥4y-x≥0.8. No monotonical change in lattice parameters with the values of x and y was observed. The sample obtained at a nominal composition of La
1.4Sr
0.6Ca
0.8 Y
0.2Cu
2O
y (x=0.2, y=0.3) showed the lowest resistivity in all materials with the "0212" structure. No superconductor was found in the "0212" structure.
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Yoshio Masuda, Kazuo Matubara, Tuyoshi Tateishi, Rikuro Ogawa, Yoshio ...
1990 Volume 37 Issue 5 Pages
772-776
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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YBa
2Cu
3O
7-x superconducting Films were prepared on YSZ ceramic substrates through sol-gel method using metal alkoxides of Y, Ba and Cu as starting materials. Cu-alkoxide could be dissolved in C
2H
4N
2(C
2H
4OH)
4 to get a homogeneous solution contained of all metal elements. Using the sols obtaind by warming the solution at 80°C, the gel films were fabricated as precoucer by dipping technique. If gel films were over 2μm of thickness by one dipping, the films happened to crack in the proccess of drying at 200°C or calcination at 500°C. Gel films could be changed to the films of 123 phase by sintering at 850°C for 30min, and the films reacted with YSZ substrates over 900°C to produced BaZrO3 and 123 phase in the films decomposed to 211 phase and CuO, more drastically to 202 phase at 950°C. To obstruct reactions with the substrate, the film's thickness was increased to 5-10μrn by repeating the dipping process. The film of l0μ m had showed Tc⋅o (R=0 Ω) at 54K higher than the film of 5μm, but to more improve CIP treatment was added to the film to get the metallic resistivity and Tc⋅o at 85K.
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Isao Amemiya, Hiroki Kobayashi, Takao Nakamoto, Takayo Hasegawa
1990 Volume 37 Issue 5 Pages
777-779
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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For the purpose of the application of superconducting oxides, preparation of the long wire and tape with low dispersion of Jc is very important. We have been attempted to preparate the long superconducting oxide tape by pyrolysis of organic acid salts on metal tapes.
In this paper we describe a study of the preparation of c-axis orientated 123 phase Y-Ba-Cu-O superconducting thick film on Ag tape with about 10m length. This tape had 1.5×10
4A/cm
2 and 9×10
4A/cm
2 of critical current densities (Jc) at 77k OT and 4.2K OT, respectively. The dispersion of Jc value was very little.
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Isao Amemiya, Hiroki Kobayashi, Kazuhira Yamaguchi, Takayo Hasegawa
1990 Volume 37 Issue 5 Pages
780-783
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
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It is known that the 124 phase Y-Ba-Cu-O superconductor is stabler on heating rather than that 123 phase. Many studies reported that 124 phase was formed in high pressure oxigen atomosphere. In order to form the phase at ordinary pressure, the alkali carbonate has been used as catalysts. So it has been difficult to prepare the long tape.
We succeeded in preparing the 124 phase Y-Ba-Cu-O superconducting thick film on Ag tape by pyrolysis of organic acid salts at ordinary pressure. The length of the tape was about 6m. The superconducting tape had 80K of Tc onset, 70K of Tc endpoint, and 2×10
4A/cm
2 of Jc at 4.2K.
We confirmed the increases of Tc of Ca-substituted sample in the same process.
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Yoshikazu Sadahiro
1990 Volume 37 Issue 5 Pages
784-787
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
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The mixture of Y
2O
3, BaCO
3 and CuO was ground by a vibration mill with allumina vessel. The products were calcined at 925°C for 2 days, and annealed at 500°C for several days. The effects of dry grinding on the samples were inferred from the variations of the strain (<εl.
2>
1/2, εl = Δ L/ L) and the lattice parameters (a, b) determined by X-ray diffraction peaks.
As the results, it has been clarified that the grinding for 100 minutes under above mentioned heating conditions gives the best conductor of these products, and comparatively eraly stage of grinding, good samples was produced, it would probably be caused by rapid decreasing of crystallite size by the grinding.
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