Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 58, Issue 11
Displaying 1-9 of 9 articles from this issue
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REVIEW
RESEARCH REPORT
  • Electrodeposition behavior of hydroxyapatite on porous electrode composed of sintered titanium spheres
    Sachiko Ono, Anita Kodama, Hidetaka Asoh
    Article type: Research Report
    2008 Volume 58 Issue 11 Pages 593-598
    Published: November 30, 2008
    Released on J-STAGE: December 30, 2008
    DOIhttps://doi.org/10.2464/jilm.58.593
    JOURNAL FREE ACCESS
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    Electrodeposition of HAp on a porous electrode of sintered titanium spheres has been studied. It took place only at the outer surfaces, but not at the inside of the porous electrode if the maximum size of spheres was 150 μm or lower. It is caused by the intricate fine structure of the electrodes composed of micro-sized titanium particles, which prevents the uniform current flow at the entire titanium surface. However, by applying pretreatments on titanium spheres electrode, deposition of HAp was remarkably improved in the following order; anodic film formation at 10 V<anodic breakdown film at 110 V<alkali treatment in NaOH. This is explicable by the addition of uniform resistance to titanium sphere surfaces at both outside and inside of the electrode, which originates from roughly structured oxide layers. As a result, uniform current flow followed by uniform hydrogen gas evolution at the entire titanium surface was induced. Furthermore, when electrolysis was performed under ultrasonic wave in addition to the oxide layer formation, electrodeposition of HAp at the inside of the electrode was dramatically improved to fulfill the space among titanium spheres. The vibration of ultrasonic wave acted an important roll to activate the evolved hydrogen gas to enhance ion migration and convection of the electrolyte. Thus, high controllability of HAp deposition on porous titanium could be attained.
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  • Surface modification of titanium by hydrothermal treatment
    Masato Ueda, Ryoichi Matsunaga, Masahiko Ikeda, Michiharu Ogawa
    Article type: Research Report
    2008 Volume 58 Issue 11 Pages 599-603
    Published: November 30, 2008
    Released on J-STAGE: December 30, 2008
    DOIhttps://doi.org/10.2464/jilm.58.599
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    The chemical-hydrothermal combined synthesis of TiO2 and CaTiO3 films on pure Ti substrates was examined with a focus on crystallinity and surface morphology of the films. Pure Ti disks were chemically treated with H2O2/HNO3 solutions at 353 K for 5–60 min in order to introduce a TiO2 layer with low crystallinity on the surface. The samples were then hydrothermally treated in an autoclave at 453 K for 12 h. Anatase-type TiO2 and perovskite-type CaTiO3 films with high crystallinity were obtained upon treatment with distilled water and an aqueous solution of Ca(OH)2, respectively. Cracks in the TiO2 precursor films disappeared after hydrothermal treatment. Uniform and crack-free films could be obtained by the present process. In addition, in vitro formation of hydroxyapatite (HAp) on the films was investigated. Obtained samples were immersed in SBF (Simulated Body Fluid), adjusted to 310 K. A light HAp precipitate could be observed on non-surface modified Ti after six days of immersion. In contrast, precipitate formed after only two days on the present oxide film. The present surface modification was confirmed to drastically promote deposition of HAp on the surface of Ti.
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  • Development of allergy-free titanium alloys for brass instruments and their characteristics
    Toshikazu Akahori, Mitsuo Niinomi, Masaaki Nakai, Harumi Tsutsumi, Tak ...
    Article type: Research Report
    2008 Volume 58 Issue 11 Pages 604-610
    Published: November 30, 2008
    Released on J-STAGE: December 30, 2008
    DOIhttps://doi.org/10.2464/jilm.58.604
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    Binary titanium alloys containing Nb or Ta, which are allergy-free and non-toxicity elements, were fabricated, and then the possibility of their application to various music instruments made of brass was investigated by the evaluation of corrosion characteristics, elastic modulus-density ratio (E/ρ), resonance frequency (f) and internal friction (Q−1) . The practical models of the mouthpieces of the trumpets made of the binary titanium alloys were also fabricated by precision casting method in order to compare directly with the sound characteristics of those made of brass and commercially pure Ti. The critical current density for the passivation of the Ti–Nb and Ti–Ta system alloys is approximately 40% lower than that of brass and nearly equal to or a little higher than that of commercially pure Ti. The Q−1 of the Ti–Nb and Ti–Ta system alloys with α″ phase drastically increase. The E/ρ and f of the Ti–Nb and Ti–Ta system alloys exhibit a positive relationship. The sound characteristics of practical mouthpieces of trumpets for a bass instrument can be controlled by changing the E/ρ and f of the alloys.
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  • Effect of isothermal aging on phase constitution and mechanical properties of Ti–Cr alloys
    Michiharu Ogawa, Toshiharu Noda, Satoshi Doi, Masato Ueda, Masahiko Ik ...
    Article type: Research Report
    2008 Volume 58 Issue 11 Pages 611-616
    Published: November 30, 2008
    Released on J-STAGE: December 30, 2008
    DOIhttps://doi.org/10.2464/jilm.58.611
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    In this study, the effect of isothermal aging on phase constitution and mechanical properties of Ti–Cr alloys was investigated by measurements of electrical resistivity and Vickers hardness, X-ray diffraction, optical and scanning electron microscope observations and tensile tests. The obtained results are as follows. In solution treated and quenched state (STQ), hexagonal martensite, α′ was identified at 3Cr and 5Cr alloys, whereas β phase was identified from 5Cr to 20Cr. In 7Cr and 10Cr, athermal ω was also identified. Maximum of HV appeared at 7Cr and then HV decreased with increase of Cr content up to 15Cr. Above 15Cr, HV slightly increased due to solution hardening by Cr addition. On isothermal aging, precipitation of the α phase was delayed by Cr addition. In STQed state, tensile strength is 961 MPa in 10Cr, 988 MPa in 13Cr and 967 MPa in 15Cr, respectively. Elongation is 27.1% in 10Cr, 26.8% in 13Cr and 23.9% in 15Cr, respectively. In 13Cr and 15Cr alloys, nominal stress-nominal strain curves showed work-softening phenomenon after yield stress, whereas S–S curve of 10Cr alloy did not show that phenomenon. In 1173 K−12 ks aged state, tensile specimens of 10Cr and 13Cr were broken with no elongation, while the specimen of 15Cr alloy was broken after about 5% in elongation. It is considered that the reason why aged 10Cr and 13Cr specimen show no elongation is due to precipitation of α.
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