Zairyo-to-Kankyo
Online ISSN : 1881-9664
Print ISSN : 0917-0480
ISSN-L : 0917-0480
Volume 69, Issue 8
Displaying 1-3 of 3 articles from this issue
Commentary
Research Paper
  • Shunsuke Yamamoto, Satoru Ando
    2020 Volume 69 Issue 8 Pages 212-220
    Published: August 10, 2020
    Released on J-STAGE: February 02, 2021
    JOURNAL FREE ACCESS

    It is well known that the types of automotive corrosion can be divided into perforation corrosion and cosmetic corrosion. Although the mechanism of perforation corrosion has been studied extensively, the mechanism of cosmetic corrosion has not yet been clarified. The authors investigated the cosmetic corrosion behavior of cold-rolled steel sheets without galvanizing with an in-situ observation device. After coating the samples by cathodic electrodeposition (ED), the sample surface was scratched with a cutter. Corrosion resistance was evaluated under cyclic corrosion test. It was found that the progress of under-film corrosion consisted of 3 steps. The 1st step occurs in the initial stage of the dry process in the 1st cycle. In this step, red rust gradually changed to black rust. The 2nd step occurs in the latter stage of the dry process, and under-film corrosion progressed from the scribed part. The 3rd step occurs in the wet process, and in this step, the tip of the under-film corrosion displayed swelling behavior. In the 2nd cycle, the 2nd step and 3rd step of the 1st cycle were repeated. Under-film corrosion progressed at almost the same rate as in the 1st cycle.

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  • Azusa Ooi, Eiji Tada, Atsushi Nishikata
    2020 Volume 69 Issue 8 Pages 221-230
    Published: August 10, 2020
    Released on J-STAGE: February 02, 2021
    JOURNAL FREE ACCESS

    Time-resolved measurement system, consisting of the combination of a commercially available solution-flow cell and an inductively coupled plasma mass spectrometry, for the dissolution rate of platinum (Pt) and palladium (Pd) has been established in this study. A detection limit of the system was successfully improved by thinning the cell channel, and their limits for Pt and Pd were 0.13 pg cm-2 s-1 and 0.39 pg cm-2 s-1, respectively. When the system was applied to Pt and Pd under potential cycling mimicking start/stop condition in polymer electrolyte fuel cell (PEFC), it was revealed that the dissolution of Pt and Pd started from the more negative potential reported in previous studies. Besides, we succeeded in the time-resolved measurement of Pt and Pd dissolution rates below open circuit potential for PEFC (ca. 1.0 V) and clarified that the dissolution mechanisms of Pt and Pd are different.

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