原位STM研究钢筋在模拟混凝土孔溶液中腐蚀和缓蚀动态行为

IN-SITU STM STUDY ON DYNAMIC BEHAVIOR OF CORROSION AND INHIBITION OF REBAR STEEL IN DIFFERENT SIMULATED CONCRETE PORE SOLUTION

应用STM原位观察在不同氯离子浓度和 pH值以及加入缓蚀剂前后的模拟混凝土孔溶液中的钢筋表面微观形貌 .在 pH =12 4 0的混凝土模拟孔溶液中 ,钢筋表面趋向均一 ,钝化膜的薄弱部分得到强化 ;在含 3 5 %NaCl,pH =10 4 0的混凝土模拟孔溶液中由于局部腐蚀的发生 ,可观察到不规则的沉积物的形成、生长 ;LD - 2型复合缓蚀剂能消除腐蚀活性 ,促使表面微观缺陷消亡 ,增加钝化膜的耐蚀能力 .研究结果说明 ,STM可在纳米尺度上观察表面形貌变化 ,可成为原位研究钢筋在模拟混凝土孔溶液中腐蚀和缓蚀的动态行为的重要手段 .

In this paper,in situ scanning tunneling microscopy(STM)was employed to investigate morphological changes on the surface of reinforcing steel immersed in simulated concrete pore solutions(saturated calcium hydroxide).The effect of chloride,pH value and LD-2 compound inhibitor on surface morphology were studied.The sequence of images recorded in different solutions tracked the process of formation and breakdown of passive film on steel surface.The result with spatial resolution in the order of nanometer obtained from STM experiment is able to provide additional information beyond electrochemical parameters and beneficial to better understanding of the mechanism of growth and breaking down of passive film on the surface of reinforcing steel.