Abstract:

The corrosion law of carbon steel under different experimental conditions was studied by linear sweep voltammetry and electrochemical impedance spectroscopy. The anodic process of carbon steel was dissolving, passivating and over passivating in ammonium carbonate solution. The mass transfer of the electrode at the initial phase was controlled by linear diffusion; with the increasing of solution temperature, the impedance spectrum was expressed as a single time constant. The diameter of reactance decreased gradually, the resistance became smaller and the corrosion rate of carbon steel increased. The greater the concentration of Cl^-, the smaller the passivation area, the corrosion of carbon steel increased. With the addition of the thiourea corrosion inhibitor, the increasing of the diameter of the reactance, the resistance became larger, which was beneficial to the protection of carbon steel.

Key words: Carbon steel corrosion, Polarization curve, Corrosion inhibitor