Behaviour of carbon steel in complexing environment at different temperatures studied by electrochemical impedance spectroscopy

In this paper, the behaviour of carbon steel in 6% Ammonium salt of Ethylenediaminetetraacetic acid dissolution (pH = 9) has been studied at temperatures between 25 and 85°C, with potentiodynamic scans and electrochemical impedance spectra at different points of polarization curves. On these curves, a reduction of the passive zone is observed when the temperature is increased. When the electrochemical impedance spectra on points of the passive zone are realized, it is observed that the nature of the film does not change in an important way with temperature variations. Likewise, passive films of Fe₃O₄ have been obtained with the polarization of carbon steel coupons at the middle of the activation zone until the current density decreased from mA/cm² to μA/cm², and these films have been characterized with electrochemical impedance spectroscopy.