钢筋在混凝土模拟液中腐蚀行为的EIS特征

A STUDY ON CORROSION BEHAVIOR OF REINFORCED REBAR IN SIMULATED PORE SOLUTION BY ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY (EIS)

研究了钢筋在不同pH和Cl^-浓度的混凝土模拟液中的电化学阻抗谱。发现钢筋在稳定钝化区、孔蚀诱导期以及孔蚀发展期的阻抗谱具有不同特征。稳定钝化时,是具有一个时间常数的单容抗曲线;在孔蚀诱导期,低频区阻抗实部呈现电感性收缩现象;在孔蚀发展期,是具有两个时间常数的曲线。建立了相应的等效电路模型,解释了钢筋在混凝土模拟液中的腐蚀机理。

The EIS of rebars immersed in simulated pore solutions of concrete with different pH values and concentrations of chloride ion was measured. The characteristics of EIS of rebar in periods of stable passivation, pit incubation and pit propagation were studied. The EIS of rebar in stable passivation was a single capacitive arc with one time constant on impedance plane. An inductive component was observed in low frequency range during pit incubation period, and the impedance plane composed of two capacitive loops during pit propagation period. The correspoding equivalent circuits were proposed respectively, which could interpret the corrosion mechanism of rebar in simulated pore solutions.