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Volume 77, Issue 2
Displaying 1-5 of 5 articles from this issue
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Regular Article
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Dai Yamamoto, Takanori Iida, Kensuke Kuroda, Ryoichi Ichino, Masazumi ...2013 Volume 77 Issue 2 Pages 33-38
Published: 2013
Released on J-STAGE: February 01, 2013
JOURNAL FREE ACCESSAnodizing of Ti specimens were performed in concentrated H3PO4 aqueous solutions with a purpose to incorporate a large amount of phosphate ion into anodized coatings, and their osteoconductivity was evaluated in in vivo test. Ti specimens were anodized in 0.1~11 M H3PO4 aqueous solutions up to 200 V at a rate of 0.1 V s−1. Anodized coatings were evaluated with SEM, TEM, XRD, XPS, and laser microscope. Anodized specimens were implanted in rats' tibia for 14 d, and then extracted.
When anodized in concentrated (≥2 M) H3PO4 aqueous solutions under spark discharge, crystallized anatase transformed to amorphous anatase by containing a large amount of PO4 3− in crystal lattice of TiO2. The amorphous anatase coatings had better osteoconductivity than the crystallized anatase coatings. It is not exactly clear what was the intrinsic factor for the high osteoconductivity, but the crystallinity of anatase and/or PO4 3− in the film is considered to be responsible for the difference in bone-forming ability of TiO2 films.
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Naotsugu Yamamoto, Jinsun Liao, Takahiro Murakami, Kazuhiro Nakata2013 Volume 77 Issue 2 Pages 39-43
Published: 2013
Released on J-STAGE: February 01, 2013
JOURNAL FREE ACCESSHybrid welding process of 10 kW class fiber laser and pulsed metal inert gas (MIG) arc was applied to pure titanium plates with thickness of 12 mm, and the hybrid weldability of the pure titanium thick plates was investigated in the present study. It is found that sound welded joints with good bead appearance and high tensile strength are available by single pass welding from both sides using the optimized welding parameters. The hardness of both weld metal and heat affected zone is slightly higher than that of base metal. Laser focal position is an important parameter, and welding spatter and defects can be remarkably reduced or prevented by focusing laser beam on back side of titanium plate.
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Masayoshi Nakamura, Mahiko Watanabe, Kisaburou Tanaka, Atsushi Kirihat ...2013 Volume 77 Issue 2 Pages 44-50
Published: 2013
Released on J-STAGE: February 01, 2013
JOURNAL FREE ACCESSUltrahigh-purity aluminum with a residual resistivity ratio (RRR) of 60000-65000 was obtained by the ultrahigh-vacuum melting method. However, it was necessary to reduce the concentration of the elements with distribution coefficient k>1 to further improve the purity of aluminum. Therefore, we prepared a sample with reduced concentrations of k>1 elements from an ultrahigh-purity (99.9999%) aluminum material by the zone-refining method, and evaluated its purity by electrical resistance measurement and glow discharge mass spectrometry (GDMS). In addition, the zone-refining process was simulated, and the distribution of the solute atoms after approximately 10 passes of zone-refining was predicted. Moreover, the refining conditions were investigated with the aim of achieving higher purity. In experiments, when the zone width was increased from 60 mm to 80 mm at a zone speed of 60 mm/h, the concentrations of the elements with k>1 in the second half of the material decreased and RRR improved. When the zone speed was decreased to 30 mm/h, a marked effect was observed and RRR increased to about 85000. The distribution of the solute atoms determined from the simulation was in good agreement with the results of GDMS analysis, thus confirming the usefulness of the simulation.
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Letters to the Editor
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Naoya Kobayashi, Takeaki Sakumoto, Shigeyuki Mori, Hiroki Ogata, Ki Ch ...2013 Volume 77 Issue 2 Pages 51-54
Published: 2013
Released on J-STAGE: February 01, 2013
JOURNAL FREE ACCESSA porous Ni electrode material for electric double layer capacitors was prepared from a commercially available Ni-Al alloy through an alkali-leaching process. The mesoporosity and metallic character of porous Ni have found to contribute to the development of higher capacitance per surface areas and superior rate performance, compared with the conventional microporous activated carbons. In an ionic-liquid electrolyte, furthermore, porous Ni has showed higher capacitance than that of microporous activated carbon, despite the specific surface area of the porous Ni was two orders of magnitude lower than that of activated carbon.
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Y. Tsujiuchi, K. Kita, C. Watanabe, R. Monzen, N. Tsuji2013 Volume 77 Issue 2 Pages 55-58
Published: 2013
Released on J-STAGE: February 01, 2013
JOURNAL FREE ACCESSAn attempt is made to enhance the strength of a Cu-1.4 mass%Ni-0.25 mass%P-0.1 mass%Zr alloy by forming ultrafine grain structure with a high dislocation density using cryo-rolling. Previously the influence of accumulative roll-bonding (ARB) and aging on the tensile properties of the alloy has been examined. The grain sizes of the alloy pre-aged at 450℃ and ARB-processed in 7 cycles (P-ARB) and the alloy pre-aged at 450℃ and cryo-rolled to a 90% reduction (P-90CR) are refined to 0.4 μm and 0.6 μm, respectively. The P-90CR alloy aged at 350℃ that has a higher 0.2% proof stress of 790 MPa and a higher ultimate tensile strength of 840 MPa than the P-ARB alloy aged at 400℃ is successfully produced. The higher strength of the aged P-90CR alloy is caused by the higher dislocation density in the alloy.
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