Abstract
The anodic reactions of carbon steel in fresh water containing bicarbonate ions or silica were investigated by the measurements of polarization curves, the surface observation and element analysis of the surface. The polarization curves of the carbon steel in the solution with low conductivity were determined by the iR compensation, where the solution resistance was obtained by using in-situ electrochemical impedance spectroscopy. The stable passive film was formed on the carbon steel surface in the solution containing 100ppm bicarbonate ions. On the other hand, though the passive film was formed on carbon steel surface in the solution containing silica, the pitting occurred during the measurement of polarization curve. The observation by laser microscope indicated that the pits were covered with the mound. The element analyses by Glow Discharge Optical Emission Spectroscopy (GD-OES) gave that the passive film and the rust, which were formed on the carbon steel in the solution containing silica, involved a large amount of Si.
