Evaluation of localized corrosion phenomena with electrochemical impedance spectroscopy (EIS) and electrochemical noise analysis (ANA)

The crevice corrosion behaviors of X52 carbon steel in two typical Cl--containing solutions were investigated by electrochemical noise and electrochemical impedance spectroscopy. Results show that oxygen concentration difference leads to the coupled current in NaCl + NaHCO3 solution while HAc concentration difference causes the coupled current in NaCl solution saturated with CO2 in the presence of HAc. There exists an apparent incubation stage during the crevice corrosion process of X52 carbon steel in the former. However, no obvious incubation period of crevice corrosion can be observed in the latter. Micrography shows that the crevice corrosion occurs indeed and the corrosion inside the crevice is not uniform.

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Characterization of Biofilm Formation and Coating Degradation by Electrochemical Impedance Spectroscopy

Coatings ◽

10.3390/coatings9080518 ◽

2019 ◽

Vol 9 (8) ◽

pp. 518 ◽

Cited By ~ 4

Author(s):

Samanbar Permeh ◽

Kingsley Lau ◽

Matthew Duncan

Keyword(s):

Electrochemical Impedance Spectroscopy ◽

Impedance Spectroscopy ◽

Microbial Activity ◽

Electrochemical Impedance ◽

Microbiologically Influenced Corrosion ◽

Localized Corrosion ◽

Steel Bridge ◽

Surface Layers ◽

Subsequent Formation ◽

Coating Degradation

Recent findings showed severe localized corrosion of submerged steel bridge piles in a Florida bridge and was associated with microbial activity in the presence of marine foulers. Microbiologically influenced corrosion (MIC) can cause severe degradation of submerged steel infrastructure with the presence of biofilm associated with microorganisms such as sulfate reducing bacteria (SRB). Coatings have been developed to mitigate MIC and marine fouling. Coating degradation and disbondment can occur as a result of microbial attack due to the production of metabolites that degrade coating chemical and physical properties. In the work described here, electrochemical impedance spectroscopy (EIS) was conducted to identify microbial activity and degradation of an antifouling coating exposed to SRB-inoculated modified Postgate B solution. The measurements resulted in complicated impedance with multiple loops in the Nyquist diagram associated with the coating material, development of surface layers (biofilm), and the steel interface. Deconvolution of the impedance results and fitting to equivalent circuit analogs were made to identify coating characteristics and surface layer formation. EIS test results revealed coating degradation and subsequent formation of surface layers associated with SRB due to coating self-polishing and depletion of biocide components.

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Corrosion Behavior of Al-Sn-Bi Alloys in Ethylene Glycol-Water Mixtures

CORROSION ◽

10.5006/0010-9312-68.5.421 ◽

2012 ◽

Vol 68 (5) ◽

pp. 421-431

Author(s):

J.L. Gama-Ferrer ◽

J.G. Gonzalez-Rodriguez ◽

I. Rosales ◽

J. Uruchurtu

Keyword(s):

Electrochemical Impedance Spectroscopy ◽

Impedance Spectroscopy ◽

Corrosion Rate ◽

Ethylene Glycol ◽

Corrosion Behavior ◽

Potentiodynamic Polarization ◽

Electrochemical Noise ◽

Electrochemical Impedance ◽

Electrochemical Techniques ◽

Potentiodynamic Polarization Curves

A study of the effect of Sn (1, 2, 3.5, 4.5, and 5 wt%) and Bi (0.5, 1.5, 3, and 4%) on the corrosion behavior of Al in ethylene glycol (C2H6O2)-40% water mixtures at 20, 40, and 60°C has been carried out using electrochemical techniques. Techniques include potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), and electrochemical noise (EN) measurements. The three techniques have shown that additions of either Sn or Bi contents increased the corrosion rate of pure Al in all cases, and that generally speaking, the corrosion rate increased by increasing the temperature except for the alloy containing 1% Sn + 4% Bi, which showed the lowest corrosion rate at 60°C. This was because of a galvanic effect from the presence of Sn and/or Bi particles on the surface alloy, which acted as local cathodes, leading to an acceleration of corrosion. Nyquist diagrams showed two semicircles at 20°C and only one at 40°C or 60°C for all the alloys, showing two different corrosion-controlling mechanisms. EN measurements showed evidence of a mixture of both localized and uniform types of corrosion for all Al-based alloys.

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