Corrosion Rate of Iron in Deaerated High Temperature Solution

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Other Title
  • 脱気高温水溶液における鉄の腐食速度
  • 脱気高温水溶液における鉄の腐食速度--浸漬初期段階での酸化物生成との関係
  • ダッキ コウオン スイヨウエキ ニ オケル テツ ノ フショク ソクド シンセ
  • 浸漬初期段階での酸化物生成との関係
  • Relation between Corrosion Rate and Oxide Growth in Initial Immersion Stage

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Description

The relation between the corrosion rate and properties of oxides on iron formed in initial immersion stage was investigated by monitoring corrosion potential (Ecorr) and corrosion resistance (Rp) in deaerated 5mol·m-3 Na2SO4 solutions of 473 to 588K. In order to understand electrochemical properties of the oxides, the reactivity of them to cathodic reduction of O2 also was investigated at room temperature in addition to identification of the oxides. Analyses of iron oxides with X-ray diffraction, laser Raman spectroscopy and SEM showed only magnetite formation, independent of exposure temperature. The temperature dependency of Rp was found to change below and above the exposure temperature of 548-573K. This temperature dependency was maintained in the measurement at room temperature in absence of O2, whilst being disappeared as changed the atmosphere to O2. Along with the behaviors in Ecorr and the O2 cathodic reduction, it was considered that the corrosion rate of iron in deaerated high temperature water was markedly dependent of the morphology of the inner oxide layer formed in the initial stage, which being characterized by pore distribution. Further, the corrosion rate below 548-573K was discussed in terms of diffusion processes of Fe2+, FeOH+ and H2O through the micropores of inner oxide layer.

Journal

  • CORROSION ENGINEERING

    CORROSION ENGINEERING 37 (6), 346-353, 1988

    Japan Society of Corrosion Engineering

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