アルカリ性電解水中における炭素鋼の腐食挙動

抄録

The corrosion behavior of carbon steel in electrolyzed alkaline water, such as sodium chloride, sodium sulfate, sodium carbonate and ammonium carbonate, was investigated. As a result of that, in electrolyzed alkaline water of sodium chloride, local corrosion was occurred in the orifice area of the carbon steel. The same phenomenon was observed in the electrolyzed alkaline water of sodium sulfate. But in the electrolyzed alkaline water of sodium carbonate and ammonium carbonate, no corrosion was generated. To clarify the corrosion behavior of carbon steel in electrolyzed alkaline water, the pH and redox potential were measured, then the corrosion potential (natural electrode potential) was measured and the anticorrosion behavior of electrolyzed alkaline water was considered. The reasons why no corrosion was generated on the carbon steel immersed in alkaline water of sodium carbonate and ammonium carbonate were assumed to be that, since there were no corrosive ions present, significant alkalization of the solution and negativation of the redox potential occurred, and the immersed carbon steel was in a state of immunity or passivation.