Electrochemical Corrosion Behavior of 10^# Carbon Steel in NaOH Solution

The effect of the temperature and content of NaOH on the corrosion behavior of 10^# carbon steel was studied through potential dynamic method and electrochemical impendance spectroscopy. The surface corrosion morphology of specimens was observed by an optical microscope. The results showed that with the increase of the temperature and content of NaOH solution, the corrosion current density of 10^# carbon steel increased, the corrosion potential decreased, and the corrosion degree increased. When the concentration of NaOH was ≤ 20%, the polarization curves had an evident passivation zone and there was a single capacitive reactance arc on the Nyquist diagrams of electrochemical impedance spectroscopy, the passivation film was complete and dense, the corrosion was relatively light, pitting occured on the surface of 10^# carbon steel when it came to transpassivation zone. When the concentration of NaOH was ≥ 30% and the temperature was >30℃, anodic current density peaks appeared on the polarization curves, the radius of capacitive reactance arc in the high frequency area of Nyquist figure decreased and diffusion impedance occurred in the low frequency area of Nyquist figure, the reaction was controlled by diffusion instead of electrochemistry, the pitting degree of 10^# carbon steel was deepened.