阳极极化状态下铁电极的交流阻抗

研究了铁电极在中性Na_2SO_4溶液中恒电位阳极极化下。和在不同pH的H_2SO_4/Na_2SO_4溶液中腐蚀电位下的交流阻抗特性。当pH>3.5时,铁电极的界面电容急剧增大至10~3μF/cm~2数量级。而铁电极在中性Na_2SO_4溶液中的界面电容为铁电极上覆盖的Fe(OH)2的电容。通过恒电位阳极极化状态铁电极的高频和低频部份的阻抗特性分析,建立了阳极极化状态铁电极的等效电路。用交流阻抗计算了极化电流密度,其值与同样条件下测得的稳态电流密度相等,说明阳极极化状态下交流阻抗测定的适用性。

THE A. C. IMPEDANCE OF IRON ELECTRODE UNDER ANODIC POLARIZATION

The A. C. impedance characteristics of iron electrode under anodic polarization controlled potential in neutral Na_2SO_4 solution and in H_2SO_4/Na_2SO_4 solutions of various pH at corrosion potential were investigated. In solutions with pH value higher than 3.5, interfacial capacitance of the iron electrode increases rapidly to 10~3μf·cm~~(-2) order. In neutral Na_2SO_4 solution, it has been shown that the interfacial capacitance is due to Fe(OH)_2 product covered on the iron electrode. Through the analysis of impedance characteristics in higher and lower frequencies of the iron electrode polarized under anodic polarization controlled potential, the equivalent circuit of the iron electrode nder anodic polarization were established, The polarized current density calculated with the A. C. impedance measurement is in agreement with the stationary current density measured in the same condition. Therefore the A. C. impedance measurement is quite suitable for polarized ellectrode.