利用可控液膜厚度的闭塞电解池, 研究了Zn在模拟酸雨本体溶液, 及薄液膜下的腐蚀行为. 在pH值为2.4--3.8的模拟酸雨本体溶液中, Zn的阻抗谱由高频容抗和低频感抗构成, Zn的腐蚀受电荷传递过程控制. Zn的腐蚀速率和腐蚀电位都随着溶液pH值降低而升高. 在较低pH值(2.4和2.7)的溶液中, 由于较强的析氢过程产生表面吸附的氢气泡, 使气泡周边的腐蚀重于Zn表面的其它区域, 而使表面形成了明显的环形腐蚀痕迹. 在薄层液膜下, 随着液膜的减薄, Zn的腐蚀过程发生变化, 当液膜减至100 μm以下时, 低频感抗为一扩散特征的Warburg阻抗代替, Zn的腐蚀控制步骤由电荷传递控制转由电荷传递和物质扩散混合控制. 研究结果表明, 液膜的减薄抑制了Zn腐蚀的阴极过程, Zn的腐蚀速率也随着液膜的减薄而降低.
The corrosion behaviors of zinc in bulk simulated acid solution and under thin electrolyte layer were studied with an occluded cell which can control the thickness of electrolyte layer. In the bulk simulated acid rain solution with pH value 2.4--3.8, the electrochemical impedance spectroscopy of zinc consists of a capacitive loop in high frequency and an inductive loop in low frequency, the control step for corrosion of zinc is charge transfer process. The corrosion rate and corrosion potential of zinc increase with decreasing pH value of solution. When pH of solution was lower (2.4 and 2.7), the hydrogen bubble absorbed on the surface of zinc was formed due to strong hydrogen process, which made more severely corrosion of zinc around bubble than the other surface of zinc, therefore, the circle trace was formed on the surface of zinc. Under thin electrolyte layer, the corrosion process of zinc changed with thinning electrolyte layer, when the thickness of electrolyte was no more than 100 μm, the control step for corrosion of zinc is a mixed process consisted of charge transfer and diffusion, and the cathodic processes are inhibited and the corrosion rate of zinc decreases with decreasing the thickness of electrolyte layer.
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