水酸化ナトリウム中でのマグネシウムのアノード酸化挙動とアルミニウムの効果  [in Japanese] Anodic Behavior of Magnesium in Sodium Hydroxide Solutions with Respect to the Effect of Aluminum  [in Japanese]

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Author(s)

Abstract

The behavior of anodic film growth on magnesium and magnesium alloys in sodium hydroxide solution was investigated with a focus on the effects of substrate composition, formation voltage, and aluminum addition. In the range of formation voltage between 2V and 110V, barrier films or semi-barrier films were formed except at around 5V and breakdown voltage. At the latter voltages, a porous type film was formed. The critical voltage of high current flow accompanied by breakdown was considerably dependent on substrate purity; namely, 60V for 99.6% Mg, 90V for AZ 31B, and 100V for AZ 91 D and 99.95% Mg. A peculiar phenomenon of high current density at around 5V may be caused by trans-passive state, similar to that associated with alkaline fluoride solution. The peak current at 5V decreased with increasing aluminum content of the substrates. These phenomena can be explained by the effects of aluminum incorporation into the film to prevent dissolution and to promote passivation of magnesium. When 1mol·dm<sup>-3</sup> AlO<sub>2</sub><sup>-</sup>ion was added in the electrolytes, the critical voltage of 99.95% Mg increased to 110V. The depth profiles of constituent elements showed that aluminum was distributed throughout the whole depth of the film. The atomic ratio of aluminum to magnesium increased with increasing voltage to attain an atomic ratio of approximately 2/3 at 100V and crystalline MgAl<sub>2</sub>O<sub>4</sub> was found in the film.

Journal

  • Journal of The Surface Finishing Society of Japan

    Journal of The Surface Finishing Society of Japan 53(6), 406-412, 2002-06-01

    The Surface Finishing Society of Japan

References:  28

Cited by:  3

Codes

  • NII Article ID (NAID)
    10008556796
  • NII NACSIS-CAT ID (NCID)
    AN1005202X
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    09151869
  • NDL Article ID
    6185263
  • NDL Source Classification
    ZP41(科学技術--金属工学・鉱山工学)
  • NDL Call No.
    Z17-291
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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