饱和NaCl溶液浸泡下混凝土试块中有机阻锈剂对钢筋腐蚀行为的影响

利用电化学阻抗谱(EIS)、半电池腐蚀电位(Ecorr)和宏观电池腐蚀电流密度(Icorr)测量技术,在饱和NaCl溶液浸泡的硬化混凝土试块中,研究了4种醇胺基阻锈剂对钢筋电极腐蚀电化学行为的影响和长期阻锈性能.在浸泡初始的100d内,与空白样相比,添加阻锈剂后钢筋电极腐蚀电位升高,阻抗膜值增大,腐蚀电流密度值降低,表明电极表面处于钝态,阻锈剂表现出良好的阻锈性能.随浸泡时间延长,电极腐蚀电位和阻抗膜值下降,腐蚀电流密度增大.浸泡后期,除添加醇胺基CI-4样外,电极电位和腐蚀电流密度与空白样相比无明显差别,表明电极由钝态转变为活性腐蚀状态.但添加CI-4样品,钢筋电极始终保持在钝化状态,阻锈性能最好.基于阻锈剂与Cl-间的竞争吸附,分析探讨了可能的阻锈机理.

Influence of Organic Inhibitors on the Corrosion Behavior of Steel Rebar inside Mortar Specimens Immersed in Saturated NaCl Solution

The long-term effects of four kinds of amine-alcohol based inhibitors on the corrosion behavior of steel rebar inside mortar specimens immersed in saturated NaCl solution were studied by electrochemical impendence spectroscopy (EIS), half cell corrosion potential (E_corr), and macrocell corrosion current density (I_corr) measurements. We found that the E_corr and the impedance modulus were higher than those in the control specimen after inhibitor addition. Additionally, I_corr decreased over the initial 100 d of immersion revealing that the steel rebar electrodes are kept in passive state and the inhibitors showed good inhibition effects. With an increase in the immersion time, E_corr and the impedance modulus for all the inhibited mortar specimens decreased while I_corr increased. After immersion for 125 d there were no obvious differences between E_corr and I_corr for the inhibited systems by comparison to those in the blank sample, except for the specimen containing CI-4. This suggests that the surface of the electrode changes from passive state to active state. The best inhibition was obtained in the presence of the CI-4 inhibitor. We briefly discuss the inhibition mechanismbased on the competitive adsorption of the inhibitor molecules with Cl^- on the steel rebar surface.