All issues
Volume 67, Issue 1
Displaying 1-10 of 10 articles from this issue
- |<
- <
- 1
- >
- >|
-
Yosihumi Ootake, Kensuke Sassa, Takashi Yamada, Shigeo Asai2003 Volume 67 Issue 1 Pages 1-6
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSA high magnetic field was imposed on the electrodeposition in a Ni-Zn system. The composition and surface morphology of deposited films were examined by changing the intensity of the magnetic field. The chemical compound in the deposited film was shifted from Ni5Zn21 to NiZn with increase of the magnetic intensity. The results of experiments are explained on the basis of macro and micro MHD (Magnetohydrodynamics) phenomena, and the condition precipitating the NiZn compound has been predicted.View full abstractDownload PDF (1447K) -
Takashi Kuroki, Nobuyuki Mori, Keisaku Ogi2003 Volume 67 Issue 1 Pages 7-14
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe nucleation and growth process of 123 (YBa2Cu3O7−x) crystals were observed in-situ to investigate the nucleation and growth process of faceted 123 crystals from the liquid+211 (Y2BaCuO5) on MgO(100) substrate through a peritectic reaction by using high temperature optical microscope with zoom lens (magnifying power of 50∼500). The nucleated faceted 123 crystals grew at a rate depended on the undercooling (ΔT). Growth rate (u) and incubation time (tinc) for nucleation were obtained from the changes in position of faceted interface during isothermal solidification. Nucleation rate (Iv) was obtained from the relationship between the number of nucleated crystals (n) and time (t). Iv was approximated by Iν={An⁄η(T)}exp(−B⁄ΔTr2), where (η(T)) was the viscosity, ΔT=Tp−T, ΔTr=ΔT⁄Tp, T was temperature, Tp was peritectic temperature, An and B were constants, An=0.60×106, B=1.2×10−3.View full abstractDownload PDF (2308K) -
Shinji Hirai, Kunihiko Suzuki, Kazuyoshi Shimakage, Satoyuki Nishimura ...2003 Volume 67 Issue 1 Pages 15-21
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIn the synthesis of α-Pr2S3 via the sulfurization of Pr6O11 powder using CS2 gas, PrS1.7, Pr4O7 and Pr2O2S were formed as intermediate products. At sulfurization temperatures above 1123 K, Pr2O2S was formed in the initial stage of reaction, and β-Pr2S3 and α-Pr2S3 were formed for a shorter period of time at higher temperature instead of Pr2O2S. In the synthesis of α-Nd2S3 via the sulfurization of Nd2O3 powder using CS2 gas, only Nd2O2S formed as an intermediate product was formed in the initial stage of reaction, and β-Nd2S3 and α-Nd2S3 were also formed for a shorter period of time at temperatures of 1073 K or higher. β-Pr2S3 and β-Nd2S3 were also thought to be oxysulfides having a limiting composition of Pr10S14O and Nd10S14O, respectively.
Next, the synthetic powders were sintered by the pressureless sintering technique. When the synthetic powder of α-Pr2S3 having a trace of residual β-Pr2S3 containing a low amount of oxygen was sintered, the compact of γ-Pr2S3 having a trace of residual β-Pr2S3 was formed at the sintering temperature of 1973 K. On the other hand, when the synthetic powder of the same α-Pr2S3 containing a high amount of oxygen was sintered, the single-phase β-Pr2S3 compact was formed at the same sintering temperature. Phase transformation of β-Pr2S3 to γ-Pr2S3 progressed preferentially with a decrease in the oxygen content of synthetic powder. In the sintering of synthetic powder of α-Nd2S3 having a trace of residual β-Nd2S3, a synthetic powder containing a low amount of oxygen was used. As a result, a single phase of γ-Nd2S3 could be prepared by sintering at 1673 K for 3.6 ks.
In hot-pressed sintering, the densification behavior of γ-Pr2S3 and γ-Nd2S3 powder prepared by the pressureless sintering and subsequent milling were also examined. The sintering kinetics could be explained by a grain boundary-diffusion mechanism that had an apparent activation energy of 247 kJ·mol−1 in γ-Pr2S3 and 347 kJ·mol−1 in γ-Nd2S3.View full abstractDownload PDF (536K) -
Hiroyuki Hayakawa, Daisuke Terada, Fuyuki Yoshida, Hideharu Nakashima, ...2003 Volume 67 Issue 1 Pages 22-26
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIn order to characterize the creep deformation mechanism of a Modified 9Cr-1Mo Steel, stress change tests were conducted during creep test. It was confirmed that the dislocation behavior during the creep test was in a viscous manner, since instant plastic strains were not observed at stress change tests. Also we obtained the mobility of dislocation by comparing the observed backward creep behavior after a stress reduction with the analysis which was based on the idea that the bakward behavior was caused with the back-motion of bow-out dislocations in a viscous manner. The analyzed dislocation mobility was in good agreement with the theoretical one.View full abstractDownload PDF (331K) -
Tsutomu Ito, Masayuki Ishikawa, Masahisa Otsuka2003 Volume 67 Issue 1 Pages 27-33
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSHigh temperature deformation characteristics of a unidirectionally solidified Al-2 mol%Cu alloy has been investigated with special reference to its ductility in solid solution temperature range. It is found that the alloy exhibits a quite large elongation to fracture of over 400% in the strain rate range from 10−4 s−1 to 10−3 s−1 and temperature range from 803 K to 821 K. The fact that the strain rate sensitivity index is about one third and that the activation energy for deformation is close to that for interdiffusion in Al-Cu alloy, together with the fact that almost no shear stress is exerted on the grain boundaries due to their arrangement in the specimen nearly parallel to the tensile axis, strongly suggest that the extra-high ductility observed here is caused not by grain boundary sliding which often governs fine grain superplasticity, but by the solute drag motion of dislocations which sometimes governs the hot deformation of solid solutions of so-called Class I type.View full abstractDownload PDF (1033K) -
Shinji Ago, Terutaka Tanaka, Tatuo Yokote, Kenji Higashida, Ryuta Onod ...2003 Volume 67 Issue 1 Pages 34-39
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThis study aims to give a mechanical explanation to manufacturing of metal (silver) foil in a traditional Japanese way in which the foils are put between Japanese papers and forged. It was clarified by forging tests carried out at various forging pressures that the forging pressure necessary for manufacturing silver foil is about 30 MPa, which is equal to one-tenth of the yield stress in a 90% rolled specimen. The test also showed that the plastic elongation of foil is of the order of 0.1% per forging (pressure is 30 MPa). This result suggests that the foil is not stretched by forging pressure, but by frictional tensile stress applied to the foil by the Japanese paper. Another test to measure the elastic property of paper showed that the Japanese paper was elongated by 0.5∼0.6% in the paper plane when it was compressed in the vertical direction at the pressure of 30 MPa. Considering the elastic strain of foil, the value of 0.5∼0.6% agreed well with the plastic elongation of foil of 0.1%. The forging tests also showed that the lower limit of foil thickness is dominated by the ability of paper not to adhere to the silver foil (removability); for example, it was 1 μm for some papers, but 0.4 μm for others.View full abstractDownload PDF (514K) -
Noritaka Saito, Kentarou Kai, Shingo Furusho, Fumiyuki Shimizu, Kunihi ...2003 Volume 67 Issue 1 Pages 40-46
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe viscosity and the solubility of nitrogen for Y2O3-Al2O3-SiO2 melts have been examined systematically. The effects of nitrogen content on viscosity for Y-Al-Si-O-N, and on Vicker’s hardness of the oxynitride glasses have been examined.
Though the viscosity of Y2O3-Al2O3-SiO2 melts was decreased, and the solubility of nitrogen into the melts was increased with increasing the content of Y2O3 for constant SiO2/Al2O3 ratio, and with increasing the content of Al2O3. These results indicate that Y2O3 and also Al2O3 behave as a network modifier. Therefore, the structural units for viscous flow become smaller, and the amount of non-bridging oxygen increases in the melts as Y2O3 or Al2O3 content increase.
The viscosity of Y-Al-Si-O-N glass melts and Vicker’s hardness of oxynitride glasses increased with increasing the content of nitrogen. These results suggest that the substitution of nitrogen for oxygen may lead to larger structural units for viscous flow, and that the increase of cross-linking produces a more rigid glass network.View full abstractDownload PDF (516K) -
Chang Dae Suk, Masahiro Kitada2003 Volume 67 Issue 1 Pages 47-52
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSColors and chemical compositions of the glaze in the Arita blue and white porcelains have been investigated. The specimens are the 17th and 19th century porcelains excavated from the kiln sites at Arita in Japan. Colors of blue pigment layers are measured by a spectrophotometer. The metallic elements of blue pigment are obtained with a wave length dispersive X-ray spectrometer. In the dominant wavelength of colors, the 17th century sample tends to situate longer wavelength area than that of 19th century samples. The border is 477 nm. The excitation purity of the 17th century samples is relatively higher than that of 19th century samples. In the glass components in glaze, SiO2 and P2O5 concentrations of the 17th century samples are higher than that of the 19th century samples. The concentrations of Al2O3 and K2O of the 19th century samples are higher than that of the 17th century samples. The amount of main staining CoO in the 19th century sample is twice as much as the 17th century samples. On the transition elements, although the relative concentrations of Fe, Ni, and Cu of the 17th century samples are high, the 19th century samples shows high concentrations of Mn.View full abstractDownload PDF (354K) -
Shunsuke Yamakawa, Katsushi Saito, Shin-ichi Towata, Shinya Morishita, ...2003 Volume 67 Issue 1 Pages 53-60
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe surface microstructure and the oxidation rate of MmNi5-based hydrogen storage alloy, exposed to water vapor at temperatures between 473 and 673 K, were investigated by transmission electron microscopy and magnetization measurements. The selected oxidation of mischmetal led to the formation of a decomposed surface layer with nanometer segregation. The surface layer was composed of a face-centered cubic phase of metallic nickel and an amorphous phase of mischmetal oxide. The metallic nickel phase was found to have the following crystal orientation relationship with the substrate MmNi5: (111)Ni\varparallel(001)MmNi5, [110]Ni\varparallel[110]MmNi5. The growth rate of the oxidized layer was proportional to the cube root of the reaction time. The rate determining step of the oxidation was a diffusion process in the oxidized layer. The apparent activation energy of the oxidation was 149 kJ/mol. Oxygen diffusion along the interface between the metallic nickel phase and the mischmetal oxide phase is discussed.View full abstractDownload PDF (1663K) -
Sumiko Sanuki, Rika Yoshimura, Nobuaki Kita, Hiroshi Majima2003 Volume 67 Issue 1 Pages 61-65
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe effect of organic acid reductants including formic acid, citric acid, oxalic acid, and tartaric acid, on the photocatalytic reduction of aqueous Se(VI) solutions was studied using TiO2 catalyst. Among the organic acids examined, formic acid was found most effective in accelerating photocatalytic reduction of Se(VI). Although tartaric acid seemed to be another important acid, it failed to complete the reduction of Se(VI). Although these organic acids were photocatalytically oxidized, their oxidation rates and amounts were small. To reduce Se(VI) to H2Se, 4∼5 molar equivalent organic acid was oxidized. However, simple chemical reduction of Se(VI) by organic acid did not occur. It is thought that the photocatalytic reduction of Se(VI) by efficient use of electrons formed on TiO2 catalyst was accelerated by the consumption of positive holes by organic acid.View full abstractDownload PDF (357K)
- |<
- <
- 1
- >
- >|