Zairyo-to-Kankyo
Online ISSN : 1881-9664
Print ISSN : 0917-0480
ISSN-L : 0917-0480
Volume 57 , Issue 8
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  • Shigeru Suzuki, Kozo Shinoda, Masugu Sato, Shinji Fujimoto, Masato Yam ...
    2008 Volume 57 Issue 8 Pages 353-357
    Published: August 15, 2008
    Released: March 17, 2009
    JOURNALS FREE ACCESS
    Measurements of X-ray absorption fine structure (XAFS), that is X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), were performed for characterizing the reactions of hydrosulphate green rust (GR) with copper or nickel sulphate ions. Fe K edge XANES spectra showed that a part of Fe(II) in GR2 was oxidized by the addition of copper sulphate ions, while Fe(II) in GR was not oxidized by the addition of nickel sulphate ions. Cu K edge and Ni K edge XANES spectra showed that copper sulphate ions were reduced to zero charge copper in the GR suspension, whereas nickel sulphate ions were not reduced. Radial structural functions for iron obtained from Fe K edge EXAFS spectra indicated that the structure of GR consisted of corner sharing of structural units formed by FeO6 octahedra. Radial structural functions for copper and nickel also indicated that copper sulphate ions were transformed to metallic copper with the face-centered cubic structure in the GR suspension, whereas the local structure of nickel sulphate ions were unchanged. XANES and EXAFS data of GR oxidized by a H2O2 solution were also investigated for comparison.
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  • Masataka Omoda, Taizo Oshika, Jun’ichi Sakai, Yuichi Ishikawa
    2008 Volume 57 Issue 8 Pages 358-365
    Published: August 15, 2008
    Released: March 17, 2009
    JOURNALS FREE ACCESS
    Corrosion factors which influence the corrosion of silver by outgassed sulfur species from vulcanized rubber have been investigated by means of quartz crystal microbalance technique (QCM) and cathodic reduction technique. Silver sulfide was the only corrosion product identified during all the tests. Corrosion progressed linearly with time and the corrosion rate did not depend on humidity, but depended markedly on the temperature and the volume of rubber contained. In addition, it is clarified that the corrosion rate varies according to the types of rubber and even among various chroloprene products. Thus it is considered that the corrosion behavior of silver with vulcanized rubber is determined by the concentration of the sulfur gas species outgassed from the rubber. The free sulfur in the rubber is assumed to be the source. It may be suggested that the outgassing of sulfur gas is determined by diffusion of sulfur molecule Sx (x=2−8) in the rubber and this diffusion process determined the corrosion rate of silver.
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