Determination of pitting corrosion stage of stainless steel by galvanodynamic impedance spectroscopy

- Measurements were performed using Galvanodynamic Electrochemical Impedance Spectroscopy (GDEIS).
- GDEIS is novel method for laboratory monitoring of pitting corrosion.
- It is possible to distinguish all stages of pitting corrosion: from passive state, to active pitting corrosion.
- Characteristic potential oscillations were detected and the source was identified.

This paper investigates the methodology for differentiation of multistep process of pitting corrosion of AISI 304 stainless steel in the environment of iron (III) chloride. Measurements were performed using Galvanodynamic Electrochemical Impedance Spectroscopy (GDEIS). Application of this methodology allowed monitoring of natural corrosion process without external current (IDC = 0A) nor potential perturbation of the system. Applied sinusoidal AC current does not influence significantly registered DC potential. Analysis confirms that it is possible to distinguish all stages of pitting corrosion: passive state, metastable state, initiation of pitting, active pitting corrosion state. Characteristic potential oscillations related with pitting corrosion were detected. Research shows that GDEIS method can be with success utilized in the monitoring of pitting corrosion.

216