Abstract
Scanning electrochemical microscopy (SECM) experiments were performed over defects on AA2024-T3 samples coated with an epoxy-based composite containing aluminum flakes covered with either tungstate- or vanadate-doped polypyrrole. The SECM probe was scanned laterally over the defect with the probe potential set to either reduce dissolved oxygen (redox competition mode) or oxidize ferrocenemethanol (feedback mode). Scans were performed over several days of immersion in naturally aerated KCl/ferrocenemethanol solution and results from three different composite coatings were obtained. Coatings containing the as-received aluminum flakes with no polypyrrole showed high levels of corrosion and corrosion product buildup, while those coatings containing polypyrrole-covered flakes showed depletion of dissolved O2 over the scribe, but with no concomitant buildup of corrosion product. The results support a corrosion control mechanism that combines galvanic coupling between the polypyrrole and the aluminum flakes, anodic passivation of the substrate, and inhibitor release into the defect. SEM/EDX was utilized to provide evidence of corrosion product formation and the release of dopant ions.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.