Electrochemical Impedance Spectroscopy as a Monitoring Tool for Passivation and Localized Corrosion of Aluminum Alloys

1991 ◽  
Vol 44-45 ◽  
pp. 83-96 ◽  
Author(s):  
F. Mansfeld ◽  
S. Lin ◽  
S. Kim ◽  
H. Shih
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Aluminum Alloys ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Localized Corrosion ◽  
Monitoring Tool

Effect of the Fe/Cu Relationship Corrosion and low Alloying Elements on Corrosion Behavior of Cast Aluminum Parts

2016 ◽  
Vol 1815 ◽  
Author(s):  
C. Rodríguez-Rivera ◽  
J.A. García-Hinojosa ◽  
F.J. Rodríguez-Gómez
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Aluminum Alloys ◽  
Impedance Spectroscopy ◽  
Corrosion Rate ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Localized Corrosion ◽  
Corrosion Mechanism ◽  
Corrosion Morphology

ABSTRACTThe aim of this study is to compare the corrosion rate of aluminum alloys for ornamental pieces. Three Fe/Cu relationships were tested in order to improve hardness and brightness in aluminum pieces since these alloys are used in the making of ornamental pieces. The variation on Fe/Cu content could result in modification on corrosion rate, since a metallographic characterization must be carried out identifying the presence of intermetallic phases. The presence of these elements could result in increasing corrosion rate, or even in modification of corrosion morphology, so localized corrosion could be expected.The assessment of corrosion rate was carried out in saline media, since chlorides are ions that promote localized corrosion. Electrochemical techniques (polarization curves and Tafel plots) were used in order to evaluate the attack in aluminum pieces; electrochemical impedance spectroscopy was also employed with voltage amplitude of 10 mV rms, and a frequency range from 10,000 Hz to 0.01 Hz. A typical three electrodes cell was used, exposing an area of one cm2. Before polarization, open circuit potential was monitored for an hour looking for a steady state. All conditions were tested for triplicate.The behavior of open circuit potential vs. time, and polarization curves was analyzed; a corrosion mechanism is proposed according to the electrochemical control. Polarization rate was calculated by using Tafel plots and, an electrochemical impedance spectroscopy analysis by using equivalent electric circuits is shown. Electrochemical impedance will yield information about corrosion morphology that is backed with microscopic inspection.The objective of this study is to compare the corrosion rate of aluminum alloys for ornamental pieces in order to determine the effect of the relationship Fe/Cu on the corrosion mechanism in aluminum parts for ornamental pieces.

scholarly journals Characterization of Biofilm Formation and Coating Degradation by Electrochemical Impedance Spectroscopy

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 518 ◽  
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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