Analysis of Electrochemical Impedance and Noise Data for AISI-310 Exposed to Lithium Bromide Solution

作者:Cuevas Arteaga C*; Brito M Luna; Molina Ocampo A; Colin J; Serna Barquera S; Torres Islas A
来源:International Journal of Electrochemical Science, 2013, 8(7): 9593-9606.

摘要

The corrosion behavior of AISI-310 in aqueous lithium bromide solution (50.0 % w/w) at 25, 60 and 80 degrees C has been studied through polarization curves (PC), the electrochemical noise technique (EN) and the electrochemical-impedance spectroscopy (EIS). Physical characterization of the corroded samples indicated that AISI-310 exposed at 25 degrees C suffered a uniform corrosion process, whereas at 60 and 80 degrees C a mixed corrosion process was observed, which was in agreement with the localization indexes calculated from EN data. The corrosion activity was analyzed taking into account the noise pattern, which was alike for the three test temperatures, observing a low amplitude/high frequency noise with some medium intensity current transients, especially at the highest temperature. EIS results showed that the temperature is an important issue in the corrosion controlled reaction, since at 25 degrees C, a pure diffusion-controlled reaction was predominantly seen, at 60 degrees C an activation-controlled step was observed, whereas at the higher temperature both diffusion and charge transfer controlled steps were observed. The corrosion kinetics was calculated from the resistance noise obtained from EN data, and then the Stern-Geary equation and the Faraday's Law were used. The corrosion kinetics showed that at 60 degrees C the corrosion rate was somewhat higher than that at 80 degrees C, which could also be seen in the electrochemical current noise, where the current density was higher at 60 degrees C. This behavior was supported due to the changes in the thermodynamic characteristics of the lithium bromide solution, since at 80 degrees C the aqueous solution at the experimental concentration tends to crystallize.

  • 出版日期2013-7