苛性ソーダ溶液中での鉄, ニッケル, およびオーステナイト系ステンレス鋼の電気化学特性に及ぼすClO₃^-の影響

抄録

Polarization measurement was conducted on iron, nickel, and austenitic stainless steels in hot caustic soda solutions containing ClO₃^- to investigate the effect of ClO₃^- on corrosion behaviors of those metals and alloys. Chlorate ions decompose into ClO^-, and this chemical reaction is stimulated by the addition of some metallic species and/or ions such as Mo (III) and Fe (II). Cathodic reduction of ClO^- to Cl^- is easy but ClO₃^- is electrochemically stable, so that cathodic reduction of ClO₃^- to ClO^- and/or Cl^- is difficult to occur directly. However, since ClO₃^- converts into ClO^- and Cl^- by consecutive reactions, ClO₃^- is detrimental to the passive film on metals and alloys in a caustic soda environment.