Zairyo-to-Kankyo
Online ISSN : 1881-9664
Print ISSN : 0917-0480
ISSN-L : 0917-0480
Volume 66 , Issue 12
Showing 1-6 articles out of 6 articles from the selected issue
Commentary
Review
Review
  • Takao Hanawa
    2017 Volume 66 Issue 12 Pages 381-387
    Published: December 15, 2017
    Released: June 06, 2018
    JOURNALS FREE ACCESS

    Metals are widely used for medical devices such as implants and about 80% of implants consist of metals, due to their excellent fracture toughness and durability. Metals are used for treatments in orthopedics and dentistry as well as cardiovascular treatments. Crevice and pitting corrosion is sometimes observed on stainless steel in the human body, while there are little examples of macroscopic corrosion in Ti and Co-Cr alloys. On the other hand, Ti element is detected from surrounding tissues and the mechanism of dissolution of Ti is discussed. Corrosion resistance of a metal is an essential property to acquire the biocompatibility and biofunction of the metal. Surface oxide film and surface hydroxyl groups on the film play an important role to determine the biological property. In addition, calcium phosphate formation on Ti is a key phenomenon to appear its good tissue compatibility. Surface treatment techniques to add biocompatibility and biofunction to metals, especially electrochemical treatments such as cathodic polarization, micro-arc oxidation, and electrodeposition of biofinctional molecule, are reviewed. Finally, importance of evaluation of corrosion resistance are demonstrated.

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Conference Publication
  • Masamichi Takebe, Makoto Ohya, Nozomu Hirose, Naoto Fukushima
    2017 Volume 66 Issue 12 Pages 395-400
    Published: December 15, 2017
    Released: June 06, 2018
    JOURNALS FREE ACCESS

    This study analyzed weathering steel test pieces that were exposed around the bridge in mountainous area for 27 years. In account of Ion transfer resistance method, corrosion level of the test pieces without supplementary rust controlling treatment coating is I-5 or I-4. In spite of the long exposure duration, their rust consists mostly of amorphous substance and a little α-FeOOH, which is considered to be main composition of protective rust of weathering steels. Weathering steel test pieces with supplementary rust controlling treatment coating retains coating with fading color among rust spots. In only case of top surface of the test piece horizontally exposed between girders of the bridge shows transformation of the treatment coating to rust. The test pieces with and without coating show little depletion of the thickness during 27 years, suggesting that environment of this area is mild in terms of corrosion and is suitable for weathering steel bridges, nevertheless inadequate formation of α-FeOOH.

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  • Masatoshi Sakairi, Ryota Sakaki
    2017 Volume 66 Issue 12 Pages 401-404
    Published: December 15, 2017
    Released: June 06, 2018
    JOURNALS FREE ACCESS

    The oxygen reduction current in thin NaCl solution layer formed on zinc electrode was measured under an open-to-air to clarify the effect of solution layer thickness, and temperatures of environments and specimens on the oxygen transport behavior. The solution layer thickness was controlled by masking by organic tape with different thickness. Independent of temperature and solution layer thickness, a clear oxygen limiting current was observed. It was increased with reciprocal of solution layer thickness as the solution layer thickness became thinner than about 0.6 mm. It was clearly shown that combination of temperature of environment and specimen was important for oxygen transport behavior through thin solution layer.

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  • Tetsuro Hosogi, Shinichi Ito, Masato Watanabe, Hisatoshi Tsueoka
    2017 Volume 66 Issue 12 Pages 405-408
    Published: December 15, 2017
    Released: June 06, 2018
    JOURNALS FREE ACCESS

    In air conditioning and refrigerant fields, ant's nest corrosion is known as the problem which caused by low carboxylic acid in the environments. In this study, CT scanner technology was recommended to observe the corrosion such as especially ant's nest corrosion in the view point of developed material estimation with accuracy. It is indicated that the issue of conventional cross sectional observation technologies and estimating its results.

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