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Volume 54, Issue 3
March
Displaying 1-13 of 13 articles from this issue
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Paper
Paper
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Yukihiro Kadogawa, Masato Hirai2007 Volume 54 Issue 3 Pages 141-145
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSYAG was synthesized by a TW method from the mixed heterogeneous solutions consists of the aqueous individual solutions made of yttrium nitrate and aluminum nitrate with the small quantity of each of tetraethyl orthosilicate and 2M-HCl, by adding the small quantity of the aqueous solution made of neodymium nitrate as additive. In this study, keeping the constant proportion of aluminum nitrate with a composition of 5.0×10−2 mole, only part of yttrium nitrate with a composition of 3.0×10−2 mole was substituted by the neodymium nitrate with a composition of 3.0×10−4 mole. YAG began to form from the constant temperature near 920°C and its single phase was obtained at a temperature of 1160°C. On the other hand, YAG single phase did not obtain because the slight amounts of the crystalline phases such as YAM, Y2O3, α-Al2O3 and θ-Al2O3 were deposited separately or simultaneously at temperatures of 1180° to 1280°C, except that the single phase of YAG was obtained at a temperature of 1300°C. It was thought that YAG single phase was obtained as YAG was produced in a reaction of YAP with α-Al2O3 at a temperature of 1160°C and in a reaction of YAM with θ-Al2O3 at a temperature of 1300°C. It was also found that the phase transformation of α-Al2O3 into θ-Al2O3 began to occur from the constant temperature near 1240°C and this phenomenon was completed by causing the disappearance of all α-Al2O3 at a temperature of 1300°C.View full abstractDownload PDF (519K) -
Yukio Makino, Takayuki Tanaka, Sumasu Yamada2007 Volume 54 Issue 3 Pages 146-151
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSEnhancement of consolidation behavior in SPS process was verified by examining the solid solution reaction between barium titanate (BTO) and strontium titanate (STO) powders, compared with that in the conventional heating method. It was found that the solid solution reaction between BTO and STO occurred at about 200°C lower temperature in SPS process than that in the conventional process. The increase of heating rate accelerated the formation of BTO-STO solid solution in the SPS process, indicating that the pulsed high current effect (that is, SPS effect) generates at higher heating rate.View full abstractDownload PDF (547K) -
Masaru Shimono, Osamu Ohtaka, Yoshinori Itakura, Hiroshi Arima2007 Volume 54 Issue 3 Pages 152-158
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSThis paper reports the thermal properties of HIP-sintered composite of diamond/SiC and its practical use to high pressure anvils. First, thermal diffusivities, specific heat capacities and expansion coefficients of the composites were measured. The obtained values were smaller than those of pure diamond and larger than SiC, respectively. The thermal conductivity is high and the expansion coefficient is low in the products whose starting materials consisted of diamond with large grain size. The photomicrographs of these products indicate that larger amount of diamond exists and the average grain sizes of diamond are large.
Secondly, temperatures of composites were measured when they were used as the anvils in 6-8 type high-pressure apparatus. Two sets of thermocouples were attached on the anvils and the temperatures under pressures were measured. Temperatures at an arbitrary point between two thermocouples were calculated using the conductivity measured in the first experiment. On the calculation, the shapes of anvils were assumed to be spherical shells instead of cubes. Since the calculated temperatures are fairy close to the measured values, this model seems to be one of methods to predict the temperatures of anvils.View full abstractDownload PDF (1021K) -
Hajime Takahashi, Susumu Mizunuma, Hidehito Okumura, Yugo Sugimura2007 Volume 54 Issue 3 Pages 159-165
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSSolid-liquid separation behaviors of grinding sludge of alloy steel (SCM440) were investigated by measuring water contents of green compacts obtained by compression tests. The sludge was easily compressed by low stresses in the initial stage of the compression because of its fibrous particle-shape. But in more advanced stage, decreasing rate of the water contents dropped significantly because of its high strength. Differences between heights after rejection and heights before unloading, namely spring backs, were very large; roughly from 35% to 45%. As the spring back leads to re-absorption of the water during the unloading after the compression, some measures for preventing the re-absorption must be applied to in the practical uses.
Furthermore, in order to investigate these compacting behaviors in wider range of properties of the particles, three kinds of commercial -use powders (Fe, Cu, and Al) were also tested together with the sludge. It was clarified that the water contents had a good correlation with the ratios of the compacting pressures to the yield stresses, and the deviations from the correlation curve were explained to occur due to the influences of the shape and the dimension of the particles.View full abstractDownload PDF (1595K)
Special Issue:Nanotechnology Materials for Environment Protection
Summarization
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Koichi Niihara2007 Volume 54 Issue 3 Pages 168
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSDownload PDF (143K)
Review
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Shigehiro Nishijima, Shin-ichi Takeda2007 Volume 54 Issue 3 Pages 169-174
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSHigh gradient magnetic separation (HGMS) can be one of the promising ways for a new environmental purification technique because of producing no contamination such as flocculants and having possibility of treating large amount of wastewater within a short time. The magnetic separation system for purification of wastewater has been developed. The test plant of 2000 ton/day was set up in the actual paper manufacturing process and a purification test of the wastewater was performed. The magnetic seeding of the organic pulp and dyes were successfully performed and the Chemical Oxygen Demand (COD) value for recycling was reached to less than 40 ppm after magnetic separation. In the present review, typical processes of magnetic seeding were classified and applicability of magnetic seeding processes using ferromagnetic microparticles was discussed. Some examples of magnetic seeding processes developed in 1970 to 2000 were reviewed and a guideline for how to choose the ferromagnetic micro/nanoparticles was described when a magnetic seeding process will be employed.View full abstractDownload PDF (879K)
Paper
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Masato Takeuchi, Takashi Kimura, Manabu Hidaka, Diana Rakhmawaty, Masa ...2007 Volume 54 Issue 3 Pages 175-179
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSTiO2 hybridized with ZSM-5 zeolites were prepared by the impregnation of (NH4)2[TiO(C2O4)2] aqueous solution. This is one of the most ideal green processes in establishing TiO2 photocatalysts because of an organic solvent-free preparation method. The highly hydrophobic H-ZSM-5 having low Al2O3 content was effective as an adsorbent for acetaldehyde. On the other hand, acetaldehyde molecules were strongly trapped on the Na+ sites of ZSM-5 and their efficient diffusion onto the TiO2 sites was inhibited. These results suggest the close relationship between the interaction of reactant with zeolite surfaces and the photocatalytic reactivity of TiO2 prepared on the zeolites as compared to unloaded TiO2 catalysts. The photocatalytic oxidation of acetaldehyde on TiO2/ZSM-5 was improved in the presence of H2O vapor.View full abstractDownload PDF (742K) -
Yoshinori Tokoi, Tsuneo Suzuki, Tadachika Nakayama, Hisayuki Suematsu, ...2007 Volume 54 Issue 3 Pages 180-185
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSAl2O3 nanosized powders were successfully synthesized by pulsed wire discharge (PWD) with gas puff. The experimental results have shown that, by using gas puff in O2 background pressure at 130 Pa, the deposited energy in the aluminum wire reached the same as vaporization energy of this wire. On the other hand, without gas puff, the deposited energy in the wire was the same as melting energy of this wire. The results of X-ray diffraction indicated that the synthesized powder with gas puff system consists of γ-Al2O3. The median diameter of γ-Al2O3 nanosized powder with gas puff was 4.9 nm. It indicated that the synthesis of Al2O3 at low pressure became to be possible by using gas puff combined with the PWD system.View full abstractDownload PDF (1162K)
Review
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Yamato Hayashi, Dai Ishikawa, Hirotsugu Takizawa, Masahiro Inoue, Kats ...2007 Volume 54 Issue 3 Pages 186-193
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSFabrication and application of nano-sized noble metal particles are introduced for newly, ecology and economy system. In this method, noble metal oxides and alcohol as starting materials are low emission (LE) materials, and we use ultrasonic irradiation as reaction energy. We have reduced noble metal oxides by ultrasound and fabricated noble nano metal nanoparticles at room temperature, and investigated various applications. By choosing suitable process and conditions, it is reasonable to be expected that these ultrasonic fabrications can be extended to obtain simply various noble metal nanoparticles related materials at total eco-design.View full abstractDownload PDF (1202K)
Paper
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Jun Inoue, Hiroki Asami, Tsuneo Suzuki, Kiyomi Nakajima, Koji Kimoto, ...2007 Volume 54 Issue 3 Pages 194-197
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSChromium oxyniride (Cr(N, O)) thin films have been successfully prepared by using pulsed laser deposition (PLD). Oxygen content in the thin films (x) was controlled by changing experimental conditions, and x of each thin film was determined to be 8, 14, 28 and 30 at.% by using Rutherford backscattering spectroscopy. The hardness of thin films was measured by Vickers hardness tester. The hardness of Cr(N, O) thin films increased with increasing x. Furthermore, morphology observation by the result of transmission electron microscope, the marked grain refinement was not observed by addition of oxygen to CrN.View full abstractDownload PDF (663K) -
Hiroki Asami, Jun Inoue, Tsuneo Suzuki, Tadachika Nakayama, Hisayuki S ...2007 Volume 54 Issue 3 Pages 198-201
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSChromium magnesium oxynitride (Cr1-x-Mgx-N-O) thin films with x ranging from 0 to 1.0 have been successfully prepared by pulsed laser deposition (PLD) method. The present work is to report oxidation behavior of the Cr1-x-Mgx-N-O thin films. From the results of oxidation tests, oxidation starting temperature of Cr0.52-Mg0.48-N-O thin film was approximately 100°C higher than that of Cr-N-O thin film. Furthermore, MgCr2O4 was formed as oxide phase in the Cr0.52-Mg0.48-N-O thin film above T=800°C. The Cr0.52-Mg0.48-N-O thin film exhibited high hardness above HV=3000 in the range from RT to T=700°C. However, the hardness of Cr0.52-Mg0.48-N-O thin film heat-treated above 800°C including MgCr2O4 phase decreased rapidly. SEM observation also revealed that voids existed in all heat-treated thin films. These voids are thought to be brought by the formation of oxide.View full abstractDownload PDF (900K)
Review
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Yoshikazu Suzuki, Supachai Ngamsinlapasathian, Keisuke Asagoe, Susumu ...2007 Volume 54 Issue 3 Pages 202-208
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSSeveral types of TiO2-based nanowire/nanoparticle composite electrodes for dye-sensitized solar cells studied by our group are briefly overviewed. In the latter part, a recent result on the structural optimization will be reported. Hydrogen titanate nanotube, which were added (10 wt%) into P-25 TiO2 matrix, pulverized to nanoparticles with some "vestigial" 1-D nanostructure during sintering process. This quasi nanowire/nanoparticle structure resulted in the improvement of efficiency: from 5.59% (pure P-25) into 7.30% (P-25 with vestigial 1-D nanostructure).View full abstractDownload PDF (1329K)
Paper
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Shuntaro Suzuki, Tsuneo Suzuki, Tadachika Nakayama, Tetsuhiko Onda, Ta ...2007 Volume 54 Issue 3 Pages 209-212
Published: 2007
Released on J-STAGE: July 03, 2007
JOURNAL OPEN ACCESSNiFe2O4+ 0∼100 vol.% NiO sintered bodies were prepared by mixing NiFe2O4 and NiO powders, and subsequent sintering at 800°C in air for 1 hour. Slopes in the temperature dependence of resistivity curves in the system have been found to abruptly changed, except for a composition of NiFe2O4+ 50 vol.% NiO. To investigate the mechanism of this phenomenon, NiFe2O4 powder was analyzed by high temperature X-ray diffraction, a thermo-gravimetry and differential thermo analysis. In the range from 100 to 300°C, the structure of NiFe2O4 phase does not change. Therefore the mechanism of this phenomenon is not related to any phase transition or the contamination of NiO.View full abstractDownload PDF (854K)
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