ELECTROCHEMICAL BEHAVIOUR OF IRON IN THE TRANSPASSIVE REGION IN 0.5mol/L SULPHATE SOLUTION
硫酸溶液中铁在过钝化区电极行为

The electrochemical behavior of the anodic passive film on iron in sulphuric acid in the transpassive region has been studied by electrochemical techniques. The duration of potential decay indicated that the film formed in the passive region become thicker with the increase of the electrode potential, in contrast, the thickness of the film formed in the transpassive region decreased as the electrode potential increased , and it is also found that the film thickness remained nearly constant above the potential of 1800mV. Also, the impedance spectra of iron were measured at different potentials. The difference between the spectra of passive layer and that of transpassive layer was shown. By fitting the impedance spectra, some parameters and information concerning the film formed in transpassive region were obtained.