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Volume 68, Issue 11
Displaying 1-6 of 6 articles from this issue
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Moriyoshi Shitara, Manabu Iguchi, Keiji Takano, Taku Tamamori, Hidehir ...2004 Volume 68 Issue 11 Pages 927-931
Published: 2004
Released on J-STAGE: June 24, 2005
JOURNAL FREE ACCESSA novel agitation method using ozone was applied to removing BOD5, CODMn, color, and NH4-N in organic waste water filled in a cylindrical vessel. The organic waste water was agitated by injecting the same organic waste water into the bath through a centered bottom nozzle. Its flow rate was adjusted to form a jet above the nozzle. A pump was used for draining the organic waste water through four nozzles settled on the bottom of the vessel and circulating it until the aforementioned four quantities were sufficiently decreased. The swirl motion of the jet appeared under certain injection conditions. The bath was strongly agitated in the presence of the swirl motion. An ozone and air mixture therefore was supplied into the nozzle and then introduced into the bath with the jet. The rate constants of BOD5, CODMn, color, and NH4-N were highly enhanced by this method compared to the conventional method using aeration of an ozone-air mixture supplied through a perforated plate.View full abstractDownload PDF (898K) -
Kinzo Murata, Takahiro Namazu, Shozo Inoue, Masaru Sugiyama, Kanryu In ...2004 Volume 68 Issue 11 Pages 932-938
Published: 2004
Released on J-STAGE: June 24, 2005
JOURNAL FREE ACCESSThe purpose of the present work is to clarify the fatigue behavior of Ni-25 mol%Mn-23 mol%Ga ferromagnetic shape memory alloy at a temperature below martensite finish temperature. Low cycle fatigue tests for single crystal specimens were carried out using a custom-made compressive testing machine which was capable to change loading conditions without interruption. The specimens were deformed with formation and propagation of Lüders bands, where rearrangement of martensite variants took place to accommodate strain under compressive loading. Fatigue failure occurred in transgranular mode by the connection of microcracks with two different directions formed at the Lüders bands. The Lüders band front was initially defined clearly, but it became unclear and wide due to the microcrack growth with increasing the number of cycles. Fracture surface was found to be lath-like, and it seemed to be consisted of the interface of martensite variants.View full abstractDownload PDF (1496K) -
Kohmei Halada, Katsutoshi Yamada, Kiyoshi Ijima, Yoshihiko Soeno2004 Volume 68 Issue 11 Pages 939-945
Published: 2004
Released on J-STAGE: June 24, 2005
JOURNAL FREE ACCESSEcomaterials were categorized based on their life cycle and eco-efficiency. Ecomaterials in their broadest sense are classified into “Functional materials of the environment”, “Materials for the advanced energy” and “Materials of life cycle design”. The materials in the first two categories improve such services as the maintenance of living environment and the efficiency in energy supply. “Materials of life cycle design” can be referred to as ecomaterials in the strict sense and are further devided into four categories according to the focus on stage in life-cycle, namely, “Materials with green environmental profile”, “Materials of higher material efficiency”, “Materials of higher recyclability” and “Materials of hazardous substance free”. Based upon this classification, current Website home pages and environmental report books of enterprises were investigated in search of commercialized ecomaterials. There are many “Materials of higher material efficiency” and “Materials of hazardous substance free” reaching the high 39% and 31% of the total respectively. “Materials with green environmental profile” gains 21%, and “Materials of higher recyclability” shows only 5%. The “Materials of life-cycle design” are obviously well represented in the market reflecting manufacturers’ determined response to the increasing appeal to consumers.View full abstractDownload PDF (1356K) -
Xuyue Yang, Hiromi Miura, Taku Sakai2004 Volume 68 Issue 11 Pages 946-951
Published: 2004
Released on J-STAGE: June 24, 2005
JOURNAL FREE ACCESSIsochronal annealing behaviors of magnesium alloy AZ31 were studied at temperatures of 373 to 673 K by optical and SEM/EBSD metallographic observation. The alloy had fine-grained structures developed by continuous dynamic recrystallization (cDRX) after hot deformation at 573 K. Temperature dependence of the average grain size (D ) is categorized into three temperature regions, i.e. (a) incubation period of grain growth at < 450 K, (b) rapid grain coarsening at 473-523 K, and (c) normal grain growth at T > 550 K. The number of fine grains per unit area, however, is reduced remarkably even in region 1. It is concluded, therefore, that grain growth takes place continuously in the whole regions. While, deformation texture scarcely changes even after annealing at high temperatures. It is concluded that the annealing processes operating in the magnesium alloy with cDRX grain structures is mainly controlled by grain growth accompanied with recovery, that is continuous static recrystallization (cSRX).View full abstractDownload PDF (1360K) -
Shin-ichi Yamaura, Yoichiro Shimpo, Hitoshi Okouchi, Motonori Nishida, ...2004 Volume 68 Issue 11 Pages 952-957
Published: 2004
Released on J-STAGE: June 24, 2005
JOURNAL FREE ACCESSWe prepared the melt-spun (Ni0.6Nb0.4)100-xZrx(x = 0 to 40 at%) and other amorphous alloy membranes and examined the permeation of hydrogen through those alloy membranes. The interatomic spacing in the Ni-Nb-Zr amorphous structure increased with increasing Zr content. The crystallization temperature of the Ni-Nb-Zr amorphous alloys decreased with increasing Zr content. The hydrogen flow increased with an increase of the temperature or the difference in the square-roots of hydrogen pressures across the membrane, Δ√p. At relatively higher temperature up to 673 K or at relatively higher hydrogen pressure difference, Δ√p up to 550 Pa1/2, the hydrogen flow was more strictly proportional to Δ√p. This indicates that the diffusion of hydrogen through the membrane is a rate-controlling factor for hydrogen permeation. The permeability of the Ni-Nb-Zr amorphous alloys was strongly dependent on alloy compositions and increased with increasing Zr content. However, it was difficult to investigate the hydrogen permeability of the (Ni0.6Nb0.4)60Zr40 amorphous alloy in this work due to the embrittlement during the measurement. The maximum hydrogen permeability was 1.3 × 10-8(mol·m-1·s-1·Pa-1/2) at 673 K for the (Ni0.6Nb0.4)70Zr30 amorphous alloy. It is noticed that the hydrogen permeability of the (Ni0.6Nb0.4)70Zr30 amorphous alloy is higher than that of pure Pd metal. These permeation characteristics indicate the possibility of future practical use of the melt-spun amorphous alloys as a hydrogen permeable membrane.View full abstractDownload PDF (1011K) -
Tsunetaka Sumomogi, Masashi Yoshida, Masayoshi Nakamura, Hiroto Osono, ...2004 Volume 68 Issue 11 Pages 958-964
Published: 2004
Released on J-STAGE: June 24, 2005
JOURNAL FREE ACCESSNanoindentation data reveal interesting behavior in aluminum with various purity levels: 99.9999%(6N), 99.99%(4N), and 99%(2N). Nanoindentation was used to investigate the relationship between the purity level and the mechanical properties of ultra high-purity aluminum at room temperature. The area subjected to nanoindentation would be expected to behave similarly to a perfect, dislocation-free single crystal. Nanoindentation data were also compared with results from conventional tension and hardness tests. These results highlight the differences between microscopic and macroscopic properties. The tensile strength and the hardness of normal-purity aluminum 99%(2N) are greater than those of ultra high-purity aluminum 99.9999%(6N) and high-purity aluminum 99.99%(4N). However, in the nanoindentation test, the penetration depth for ultra high-purity aluminum (6N) and high-purity aluminum (4N) is less than that for normal-purity aluminum (2N). Thus, microscopic mechanical properties differ from macroscopic mechanical properties. It is suggested that the surface of high-purity aluminum is harder than that of normal-purity aluminum on the micro scale. The experimental result shows that a perfect crystal is harder than an imperfect crystal. Furthermore, some recovery of the indentation mark was observed in high-purity aluminum, caused by the mobility of defects in the sample.View full abstractDownload PDF (1300K)
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