Abstract
We have been investigated the effects of residual carbon on the corrosion of copper tubes. In the previous study, the developed water treatment chemical could suppress pitting corrosion of copper tube even with 6.1 mg/m2 of residual carbon amount in the field test. The effects of the residual carbon and the water treatment chemical were investigated by the electrochemical characteristics using the actual open circulation cooling water. In the anodic polarization measurement under the deaerated condition, the tube with the residual carbon showed a lower natural potential and a higher current density than those of the tube without the residual carbon. In the cathodic polarization measurement under the open–air condition, the tube with residual carbon showed a higher natural potential and a lower current density than those of the tube without residual carbon. Regarding the difference between the water treatment chemicals, there was no significant difference in cathodic polarization behavior, however, a difference in anodic polarization behavior was observed. In the treatment with the developed chemical, the current density at near 0 mV vs. SSE tended to be slightly higher with residual carbon of 6.6 mg/m2 or more than it of 0.5 mg/m2 or less.
