材料期刊网

The corrosion of Fe and Ni covered with a molten film of 0.55ZnCl(2)-0.45KCl was examined in air at 673K by the electrochemical-impedance spectroscopy (EIS) technique. Meanwhile, the impedance behavior for Fe and Ni immersed in the deep salt was also studied for comparison. The EIS for Fe beneath a thin salt film and in deep salt both showed a semicircle at high frequency and a line at low frequency, indicating a diffusion: controlled reaction, but with much larger impedance in deep salt. The corrosion of Ni beneath a salt film was composed of two stages with different EIS features. The initial Nyquist plots also showed the characteristics of a diffusion-controlled reaction, as for the impedance features of Ni in deep salt, but converted into two capacitance loops at longer times. Equivalent circuits representing the corrosion of Fe and Ni were proposed to fit the corresponding impedance spectra and electrochemical parameters in the equivalent circuit were calculated.