关键词: 碳钢, 缝隙腐蚀, 外内表面积比, 电化学噪声, 电化学阻抗

Abstract: The crevice corrosion behavior of Q235 carbon steels in a NaHCO3+NaCl solution was investigated by electrochemical noise(EN) and electrochemical impedance spectroscopy(EIS).Three stages of crevice corrosion including the induction,the rapid transform and the stable development could be clearly distinguished.The characteristics of the electrochemical noise and the noise resistance Rn showed remarkable differences at each stage.The electrode area ratio(r) of outside to inside the crevice had a significant influence in the development of crevice corrosion.The time of the induction stage increased with increasing r.However,under the stable development stage of the crevice corrosion,the surface outside the crevice was at an active dissolution state when r was small,while the potential difference between outside and inside the crevice and the corrosion rate inside the crevice were small.When r was big,the surface outside the crevice was at a passive state and the potential difference between outside and inside the crevice was large,which causes serious crevice corrosion.

Key words: carbon steel, crevice corrosion, area ratio of outside to inside crevice, electrochemical noise, electrochemical impedance