All issues
Volume 42, Issue 5
Displaying 1-19 of 19 articles from this issue
- |<
- <
- 1
- >
- >|
-
[in Japanese]1995 Volume 42 Issue 5 Pages 556
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (85K) -
Takeshi Nomura, Yukie Nakano, Yoshikazu Izumi1995 Volume 42 Issue 5 Pages 557-566
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDegradation behavior of insulation resistance(IR) of BaTiO3-based Ni-electrode multilayer ceramic capacitors (MLCC) has been studied with special reference to the material parameters. The degradation behavior shows clear dependence on the ambient atmosphere during firing, the doping, and the grain boundary chemistry. The degradation of IR is thought to be caused by the electrolytic migration of oxygen vacancies. A/B of grain boundary should be higher than the unity, in order to achieve long life. Consequently, we have developed high capacitance MLCCs as 10.5μF in 3216 type with superior reliability.View full abstractDownload PDF (5429K) -
Naoki Kawano, Yukie Nakano, Akira Sato, Tomohiro Arashi, Junko Yamamat ...1995 Volume 42 Issue 5 Pages 567-571
Published: May 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn X7R characteristic Ni-electrode MLCCs with the composition of BaTiO3-MgO-MnO-Y2O3-Ba0.6Ca0.4SiO3 system, the effect of the firing condition on the aging of capacitance under DC field has been studied.The aging was promoted by the annealling for the reoxidation of the dielectric body and the firing under the low oxgen partial pressure. It is presumed that the lattice defects (cation and oxgen vacancies) promote the aging.We showed that the aging behavior is good coincident with the Richter-type relaxation equation model.The activation energy which was estimated from the relaxation time was about 0.59-0.86 eV.It is presumed that the aging is brought about by the more mobile substance than the anion(oxgen).View full abstractDownload PDF (2612K) -
Shinichi Sato, Katsuhiko Igarashi, Takashi Kamiya, Takeshi Nomura1995 Volume 42 Issue 5 Pages 572-576
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effect of structural factors on the bending strength of nultilayer ceramiccapacitor (MLC) monuted on a printed circuit board has been studied, with specialreference to the termination electrodes of MLC. Capacitance of MLC suddenly decreases duringthe bending test. This decrease is caused by the breakage of the ceramic body whichinitiated at the edge of the termination electrodes. It is also shown that theamount of the solder, the shape of termination electrodes, and the bending strength of ceramicbody are the important factors. FEW analysis supported the results. Furthermore, the fluctuation of the bending strength was affected by the position of MLC on the board.View full abstractDownload PDF (2482K) -
Kazuya Takemoto, Masayuki Yamada, Kenji Tanaka, Kazuyori Urabe, Toshih ...1995 Volume 42 Issue 5 Pages 577-581
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHot-forging process was employed for preparing polycrystalline BaTiO3 dielectric ceramics. The BaTiO3 powder was first mixed with a small amount of additives and then encapsulated in a stainless steel (SUS 304) mold with inner, outer diameter and height of 10, 22 and 30 mm, respectively. The mold containing the mixture ceramic powders was preheated at 1000°-1300°C for 8 minutes to minimize the gradient of temperature inside the mold and press-forging under uniaxitial compressive load was immediately applied. The deformation ratio of the mold was about 50 % as calculated from the initial and final heights of the mold. Fully dense specimens were obtained when the preheating cycle was conducted at 1100°C. The microstructural development of the sintered body was monitored by careful microscopy which revealed complex structural features in the crystal grains. It was found the hot-forged dense polycrystalline specimens, when annealed at 1100°C for 12 hours, developed a 'core-shell' structure which can lead to temperature-stability of dielectric properties of BaTiO3 ceramics.View full abstractDownload PDF (3873K) -
Takahiro Yamakawa, Tohru Ezaki, Mamoru Ishii, Shigeru Takahashi1995 Volume 42 Issue 5 Pages 582-586
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe influence of MnCO3 addition on the sintering behaviour of PZT ceramics was investigated. In proportion as amount of MnCO3 addition increased, the relative density of sintered body decreased. The shrinking curves during sintering showed the following features ; Starting temperature of shrinking shifted higher as amount of MnCO3 addition increased. These shrinkages were able to classify into two stages;at the first stage, the shrinking speeds of specimen were relatively slow, but at the second stage, those were rapid. Achieved shirinkage values of each specimen were corresponding to the relative densities. The grain growth behaviour was investigated with SEM micrographs. On the specimen with 0.4wt% MnCO3, rapid grain growth occurred only between 1050°C and 1150°C, but slow grain growth continued over 1150°C.
On the specimen with 0.8wt% MnCO3, grain growth did not occured till 1150°C, but rapid grain growth continued over 1150°C. We conclude that the MnCO3 is not useful for PZT ceramics as a sintering aid.View full abstractDownload PDF (2322K) -
Shunji Takeda, Kunihito Koumoto, Hiroaki Yanagida1995 Volume 42 Issue 5 Pages 587-591
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTwo kinds of commercial ZnO system varistors were investigated with relevance to their microstructures. Particularly, face-to-face fracture surfaces were characterized in terms of secondary electron image and backscatterd electron image to clarify the existence of precipitates at the grain-to-grain interface. It became more clear that the grain-to-grain interface was free of precipitates. This result agreed well with the observation carried out with a scanning transmission electron microscope and a high-resolution transmission electron microscope. Lattice spacings of ZnO grains in ZnO-Bi system varistor were found to be abnormally large which was considered to be associated with the segregation of bismuth to the grain-boundary region.View full abstractDownload PDF (3914K) -
Tomohiro Sogabe, Shigeki Sato, Masahito Furukawa, Takeshi Nomura, Mino ...1995 Volume 42 Issue 5 Pages 592-597
Published: May 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSEffect of sintering atmosphere on maximum-energy capability of Pr-doped ZnO varistor has been studied with special reference to the microstructure. It is shown that maximum-energy capability and non-linearity are effectively improved by both introducing N2 at the heating up process of sintering and annealing at 1200°C under O2 atmosphere at cooling process. Maximum-energy capability strongly depends on the uniformity of grain size . According to the complex impedance analysis, it was found grain-boundary resistance increased and grain resistance decreased with N2-Air-O2 sintering. TEM-EDS, C-V characteristics and ICTS analysis showed that non-linearity depended on acceptor concentrations N3 which were mainly contributed by adsorbed-oxygen on Pr2O3 at grain boundaries. Interface state was calculated as 0.78eV. It was clarified by V-I characteristics of one grain boundary that grain boundary contributes varistor characteristics.View full abstractDownload PDF (3323K) -
Yoshito Nihira, Takeshi Nomura1995 Volume 42 Issue 5 Pages 598-602
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effect of thermal decomposition conditions on the powder properties of Fe3O4 has been investigated, in order to obtain fine Fe3O4 powder. It is shown that the one phase Fe3O4 could be obtained under the following conditions, water vapor pressure is 0.1MPa, and thermal decomposition temperature is between 550 and 800°C. Fine Fe3O4 powder could be obtained by introducing FeCls or O2 at the thermal decomposition of FeCl2. It was found that FeO was not formed when FeCl3 was introduced.View full abstractDownload PDF (1344K) -
Kiyoshi Ozawa, Yoshio Sakka, Muneyuki Amano1995 Volume 42 Issue 5 Pages 603-607
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSLiSbO3 is useful not only as a Li ionic conductor but also as a raw material of monoclinic acid, which is synthesized only by ion-exchanging Li+ ion in LiSbO3 with H+ ion in acid solution. To obtain fine LiSbO3 powder sol-gel processing of metal alkoxides was investigated. A mixed alkoxide solution of lithium n-propoxide (LiO-n-C3H7) and antimony n-propoxide (Sb(O-n-C3H7)3) was refluxed, hydrolyzed, dried, and calcined. The process was examined by TG-DTA, XRD and SEM observation. The as-precipitated powder began to crystallize at 420°C and single-phase LiSbO3 was prepared after heating the precipitate at temperatures above 500°C in air. Monoclinic antimonic acid was synthesized by the ion exchange reaction of the obtained LiSbO3 powder in HNO3 aqueous solution.View full abstractDownload PDF (1811K) -
Yuji Muramatsu, Tsuneo Ohkoshi, Hiroo Suga1995 Volume 42 Issue 5 Pages 611-617
Published: May 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSTiAI intermetallic compounds containing 5-15at% Nb were prepared by sintering mixed powder compacts of TiH2, TiAl3 and NbAl3. The sintered compounds were further densified by HIPing at 1470K and 202MPa for 3.6ks without canning. Densifications by sintering and HIPing were examined as functions of Nb content, sintering temperature and sintered density. The microstructure of sintered and HIPed compounds was also examined. These experiments showed that both densifications by sintering and HIPing were diminished with increased Nb content. However, full densification was achieved when Nb contents were less than 10at% for 45at%Al compounds. HIPed density increased with increased sintered density, and became saturated when the relative sintered density exceeded 92% for Ti-45Al-10Nb(at%) compound. The microstructure varied with sintering temperature, and the lamellar structure increased with the rise of the sintering temperature. X-ray analyses on HIPed compounds exhibited B2-phase together with α2 and γ phases.View full abstractDownload PDF (5182K) -
Tatsuro Isomoto, Hiroshi Nagai1995 Volume 42 Issue 5 Pages 618-622
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPowder metallurgy SUS304 stainless steels consolidated by hot extrusion process with different oxygen contents from about 100 to 250 ppm were investigated in terms of mechanical properties at elevated temperatures. Dispersion of oxide inclusions consisting of Cr-Mn-Al was observed while granular alumina was found in the conventional material. For the slow strain rate testing, tensile strength of powder metallurgy SUS304 was higher than the conventionally produced counterpart at temperatures up to 800°C, irrespective of oxygen content. The value of reduction of area decreases with increasing oxygen content in the powder metallurgy material tested at temperatures from 650 to 950 °C. For the high strain rate testing from 850 to 1400°C, the powder metallurgy materials showed higher strength and ductility than the conventional material in the entire range, independent of oxygen content.View full abstractDownload PDF (4306K) -
Kunihiro Nagata, Shuichi Kinoshita1995 Volume 42 Issue 5 Pages 623-627
Published: May 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe degradations of multilayer ceramic actuator on high humidity were studied under the applying DC field and AC field voltage. On the applied DC field and AC field, the logarithms of life times were in proportion to logarithms of the applied volt ages, and the life times on humidity of 85%RH were shorter about 102-103 figures than those of 10%RH.View full abstractDownload PDF (268K) -
Hirohiko Fujimaki, Tetsuya Takaai, Manabu Kiuchi1995 Volume 42 Issue 5 Pages 628-633
Published: May 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn this study, the aluminum oxide dispersion strengthened copper (ODSC) wire, in which fine Al2O3 dispersed uniformly, was developed and made into wires as a copper alloy wiring harness with high tensile strength and high electrical conductivity. The relationships between internal oxidation temperature and wire's mechanical and electrical properties were investigated from a viewpoint of the wire's internal structure by using optical microscope, scanning electron microscope and transmission electron microscope. As a conclusion, it was confirmed that aluminum in Cu-Al alloy powder was almost all oxidized into Al2O3 by internal oxidation at 600°C for 1h in the composition of Cu-0.35mass%A1. And this ODSC wire's tensile strength was 540N/mm2, elongation was 9% and electrical conductivity was 88%IACS.View full abstractDownload PDF (2715K) -
Minoru Saito, Osamu Terada, Hisashi Suzuki1995 Volume 42 Issue 5 Pages 634-638
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt has been known by the present authors that some projections and inclusions are often observed on CVD coated films and in the same films on cemented carbides substrate, respectively. The characteristics and the source of inclusions were mainly studied, using commercially available coated cemented carbides tools for cutting steels, and specimens prepared in the authors' laboratory. The results obtained were as follows. The projections were closely related to the inclusions, because projections usually developed just over inclusions. The inclusions were the small particles consisting of TiC, TiN, etc. It was considered that, during CVD, the substance crystallized on the inner surface of carbon-tray (for setting samples) was broken, and produced fine particles were transferred with gas flow to the substrate surface, resulting in the inclusions wrapped in the films. The size and number density of projections or inclusions varied depending on the location of substrate surface in relation to the direction of gas flow.View full abstractDownload PDF (5423K) -
Tetsuo Kato, Noriyoshi Kurata, Makoto Kawamura, Katsushi Kusaka1995 Volume 42 Issue 5 Pages 639-644
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn the sintered iron-chromium magnetic alloy, the influence of the addition of some oxide powders for the micro-structure and magnetic properties was studied. There were many pores after sintering by the addition of SiO2 and Al2O3 powders, compared with those for no-addition. On the contrary, there were fewer pores with the addition of CaO and their mixed and melted oxide powders. The sintered density became higher in the order of mixed oxides and melted oxides, CaO, non-oxides, SiO2 and Al2O3 powders addition. The amplitude relative permeability in the direct magnetic field became higher in the order of mixed oxides and CaO powders addition than non-addition at the lower sintering temperature and became to nearly equal either at the higher temperature. And the permeability was lowering in SiO2 and Al2O3 powders addition. In the alternating magnetic field, on the contrary, the amplitude relative permeability became clearly higher with the addition of mixed oxides and CaO powders than non-oxides and others. It is presumed that the highest magnetic property in the alternating magnetic field in the mixed oxide powder addition comes from not only the density improvement effect by CaO but also the control effect by SiO2 and Al2O3.View full abstractDownload PDF (608K) -
Hidetoshi Kotera, Ayumu Onoyama, Susumu Shima1995 Volume 42 Issue 5 Pages 645-650
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPermanent magnet is made of ferromagnetic powders by compaction in a magnetic field. The magnetic powder has an anisotropic property in magnetization. The magnetic axis of each particle is forced to be oriented in the direction of magnetization. However, the axis of magnetization is also rotated by a series of mechanical forces under compaction. To control the characteristics of permanent magnet for electronic devices, it is of great importance to understand the movement of the magnetic particles during compaction in the magnetic field. This paper presents how the easy direction of magnetization is aligned in the magnetic field during three methods of compaction; compaction where the compacting direction is either perpendicular or parallel, and isostatic. It is thus shown that the magnetic characteristics of the compact are dependent on the direction of compaction to the applied magnetic field. The calculated results of the magnetic characteristics of the compact are also shown.View full abstractDownload PDF (463K) -
Hisashi Kuwano, Hiroyuki Morita, Toru Ishigaki1995 Volume 42 Issue 5 Pages 651-654
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPure Mo powders are mechanically attrited with a hardened steel vial and balls in an Ar atmosphere to produce nanostructural and amorphous Mo-Fe alloys. A time evolution of the solid state amorphization caused by the attrition is classified into three stages. In the initial stage the crystallite size of Mo decreases down to 10 nm together with the increase in the lattice strain up to 1.8%. Plastic deformation is a dominating cause of the crystallite size reduction. In the next stage, the crystallite size decreases down to a minimum dimension of 5nm. The reduciton of the grain size is accompanied by a decrease in the lattice strain and the solid solutioning of the Fe impurities which are introduced from the vail and balls in the prior stage. The grain size reduction in this stage is interpreted in terms of recovery process of the stored strain. In the final stage where the Fe content in the Mo lattice saturates about 18at%, a transition from the nano-crystallites to an amorphous phase takes place.View full abstractDownload PDF (310K) -
Kiyohiko Tatsuzawa, Tatsuhiko Aizawa, Junji Kihara1995 Volume 42 Issue 5 Pages 655-660
Published: May 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSControlled fracture forming(CFF) of metal/alpha-alumina composite wires and fibers was mainly studied with respect to the strength of alumina resintered into composite wires sheathed by nickel or austenitic stainless steel. The hardness of resintered alumina decreased with total reduction of cold working, because the densification of alumina should be prevented by contamination of sheath-metal constitutive elements during processing. In order to improve this resinterability, pure aluminum foil was inserted into the interface between metal sheath and presintered alumina, and worked by CFF processing. These green composite wires were resintered at 1623K for 3.6ks in nitrogen atmosphere. This processing is effective to fabricate dense alpha-alumina/metal composite wires and fibers to be used in practical applications.View full abstractDownload PDF (4482K)
- |<
- <
- 1
- >
- >|