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研究了AM60镁合金在0.1 mol/L NaCl,Na2SO4和饱和Mg(OH)2溶液中浸泡96小时的电化学阻抗谱(Electrochemical impedance spectroscopy,EIS)行为。溶液中含有Cl-时,阻抗谱呈现高中频两个容抗弧和低频感抗成分,且低频感抗组分在浸泡36小时后消失。AM60浸泡在Na2SO4溶液中具有类似的电化学阻抗行为,区别在于低频弛豫过程和容抗大小。相比于Cl-离子,SO42-离子具有相对较弱的腐蚀进攻能力。在饱和Mg(OH)2溶液中,由于Mg(OH)2弱水解有效抑制了阴阳极反应(极化曲线结果),EIS谱图仅有中高频两个容抗弧,没有对应孔核形成和消失的低频感抗行为。由于高频容抗弧对应AM60原表面的双电层信息,其弥散系数n、分形维数DE可以获取腐蚀过程中的细节信息。阻抗分形维数DE随时间的变化曲线结果表明Cl-具有最强的腐蚀进攻性,同时也具有再钝化效应,以修复由于Cl-进攻形成的孔核。SO42-离子腐蚀进攻性相对较弱,且没有再钝化现象。饱和Mg(OH)2溶液中DE的增加主要是由于不溶性Mg(OH)2沉积吸附在镁合金表面,增加表面的粗糙度。
The electrochemical impedance spectroscopy (EIS) behavior of AM60 magnesium alloy immersed in 0.1 mol / L NaCl, Na2SO4 and saturated Mg (OH) 2 solution for 96 hours was studied. When the solution contains Cl-, the impedance spectrum shows two high-frequency tolerant arc and low-frequency inductive reactance components, and the low-frequency inductive component disappears after soaking for 36 hours. AM60 immersed in Na2SO4 solution has a similar electrochemical impedance behavior, the difference lies in the low-frequency relaxation process and the size of the capacitive reactance. Compared to Cl- ions, SO42- ions have a relatively weaker corrosion attack ability. In saturated Mg (OH) 2 solution, the cathodic reaction (polarization curve) was effectively suppressed due to the weak hydrolysis of Mg (OH) 2. The EIS spectrum had only two capacitive arcs at middle and high frequency, Disappearance of low frequency inductive behavior. Due to the electric double layer information corresponding to the original surface of the AM60, the diffusion coefficient n and the fractal dimension DE can obtain the details of the corrosion process. The results of the impedance fractal dimension DE with time show that Cl- has the strongest corrosion attack and also has the reactivation effect to repair the pore nuclei formed by Cl-attack. SO42- ion corrosion attack is relatively weak, and no further passivation phenomenon. The increase of DE in saturated Mg (OH) 2 solution is mainly due to the deposition of insoluble Mg (OH) 2 on the surface of magnesium alloy, which increases the surface roughness.