材料期刊网

应用循环伏安与动电位极化曲线确定普通低碳钢与细晶粒钢在碱性介质(模拟混凝土孔隙液)中的钝化区域. 利用计时电流法在选取的阳极极化电位下使钢筋生成稳定的钝化膜, 并通过电化学阻抗谱、 Mott-Schottky曲线比较了钢筋在不同阳极电位下形成的钝化膜的优劣性; 其次, 循环极化曲线对比分析了在有无Cl^-存在时普通低碳钢与细晶粒钢钝化膜的耐蚀性. 结果表明, 2种钢筋的公共钝化电位区域为 -0.25-+0.6 V, 在选取的+0.3 V阳极极化电位下2者均能形成更稳定的钝化膜. 在无Cl^-存在的条件下, 细晶粒钢钝化膜的稳定性与耐蚀性均略优于普通低碳钢; 但有Cl^-存在时, 细晶粒钢抑制Cl^-点蚀的能力稍弱于普通低碳钢. 影响细晶粒钢钝化膜耐蚀性的主要原因是晶界数量与微量元素含量.

The passive ranges of low-carbon rebar and fine-grained rebar in simulated concrete pore solution with pH13.0 were determined by means of cyclic voltammetry and potentiodynamic polarization curves. Chronopotentiometry was used to obtain steady state conditions for the formation of passive films on rebar samples at different anodic potentials. Electrochemical impedance spectroscopy and Mott-Schottky curves were employed to compare the passive films formed at different potentials. Additionally, cyclic polarization curves were used to compare the corrosion resistances of passive films formed on the two rebars in alkaline media with or without Cl^-. The results show that the passive ranges of the two rebars are all between -0.25 and +0.6 V, and the more stable passive films can be formed on both rebars at the anodic potential of +0.3 V. In the absence of Cl^-, the stability and corrosion resistance of the passive film formed on the fine-grained rebar are better than those of low-carbon rebar. However, the pitting corrosion resistance of the former is somehow lower than that of the latter in the presence of Cl^-. The amounts of grain boundary and trace elements are responsible for the lower corrosion resistance of fine-grained rebar.