铝基水滑石涂层腐蚀行为的电化学噪声特征

Electrochemical Noise Characteristics of Corrosion Behavior of Al-based Hydrotalcite Coatings

采用电化学噪声技术监测了铝基水滑石涂层在3.5%NaCl溶液中的腐蚀行为。通过电化学噪声的时域谱分析、时域统计参数分析、频域分析以及形貌特征分析,对电极的腐蚀过程进行了研究。结果表明,涂层的点蚀发展过程可以分为4个阶段:钝态期,噪声波动较小,各参数比较平稳;亚稳态点蚀核形成期,噪声出现波动,σV、σI、W、k、fc增大,Rn减小;稳态点蚀发展期,电位噪声出现快速下降缓慢上升的典型特征,各参数趋于极值,Li(局部化噪声指数)接近于1;点蚀发展后期,噪声波动减弱,各参数值也趋于减弱。

The corrosion behavior of Al-based hydrotalcite coatings in 3. 5% NaCl solution was characterized by electrochemical noise analysis technique. The corrosion process of electrodes was studied in detail by analyzing timedomain and frequency-domain characteristics of electrochemical noise （EN） together with morphology features. The results showed that the pitting corrosion process of coatings could be divided into four different stages. At passivated stage, the EN fluctuated slightly, and the parameters were relatively stable. At metastable pitting nucleation stage, the EN began to fluctuate obviously, av, m, W and fc increased, R~ decreased. At stable pitting corrosion stage, the potential declined rapidly and rised slowly, meanwhile various parameters tended to extremum and Li （localization index） was close to 1. At later pitting corrosion stage, the EN fluctuated slightly and various parameters tended to be weakened.