采用Tafel直线外推法、电化学阻抗谱和中性盐雾腐蚀试验研究了电力系统用LF21铝合金在5% NaCl溶液中的电化学腐蚀行为, 利用SEM和EDS表征材料的腐蚀形态与腐蚀产物组成, 并探讨腐蚀机理. 结果表明, LF21铝合金在5% NaCl溶液中耐蚀性很差. 随着电解液温度升高, 铝合金的自腐蚀电位负移, 腐蚀速率变大. 电化学阻抗谱显示其容抗减小, 膜电容下降, 合金表面的保护膜被破坏. LF21铝合金在NaCl介质中的腐蚀主要以点蚀为主, 形成较深的腐蚀坑, 点蚀部位O含量明显增高.
The electrochemical behavior of LF21 aluminum alloy, as a major base materials used in electric power system, in 5% NaCl solution were investigated by Tafel linear extrapolation method, electrochemical impedance spectroscopy technique and neutral salt spray test. The surface morphology and chemical composition of the corrosion product of the alloy were examined by scanning electron microscope and energy dispersive spectrometer, respectively. The results showed that LF21 aluminum alloy exhibited poor anti-corrosion performance in 5%NaCl solution. When the temperature of solution increased, the corrosion potential of LF21 aluminum alloy shifted negatively, and the corrosion current density increased. Meanwhile, the capacitive resistance and film capacity decreased with the increasing of the solution temperature, implying that the protection film on the surface of material was deteriorated to some extent. The major corrosion form of LF21 aluminum alloy in NaCl solution was pitting corrosion, and the corrosion resulted in much deeper corrosion pits.