In-situ measurement of electrochemical activity related to filiform corrosion in organic coated steel by scanning vibrating electrode technique and scanning micropotentiometry

A new approach to studying the mechanism of filiform corrosion in organic coated steel based on the scanning vibrating electrode technique (SVET) and micropotentiometry (potentiometric SECM) is presented. The electrochemical activity of the process under the coating is evaluated by mapping the ionic current densities emanating from some artificial defects made in specific locations of the filament identifiable thanks to the transparency of the coating. In addition, antimony tips are employed to investigate the pH changes associated to the different corrosion reactions at the metal-paint interface. Local pH levels associated to anodic and cathodic regions are determined along the filament.

Automated summary

This study presents a new approach to studying the mechanism of filiform corrosion in organic coated steel using the scanning vibrating electrode technique (SVET) and micropotentiometry (potentiometric SECM). The electrochemical activity under the coating was evaluated by mapping the ionic current densities coming from artificial defects made in specific locations of the filament. Antimony tips were also used to investigate the pH changes associated with different corrosion reactions at the metal-paint interface. Local pH levels along the filament in the anodic and cathodic regions were determined.