Pit Morphology, Dissolution Kinetics, and Gas Generation Monitored in Real Time during Localized Anodic Aluminum...

Area of Science:

• Materials Science
• Electrochemistry
• Corrosion Science

Background:

• Localized corrosion is a significant cause of structural failure in metallic materials.
• Understanding the initiation and progression of corrosion at the nanoscale is crucial but challenging.
• Current methods struggle to characterize the early stages of corrosion in real time.

Purpose of the Study:

• To investigate the real-time kinetic mechanism of localized anodic corrosion in thin-film pure aluminum.
• To characterize the evolution of pit morphology during corrosion.
• To identify the gaseous byproducts of aluminum corrosion.

Main Methods:

• Development and application of an experimental platform combining electrochemical liquid-phase scanning electron microscopy (LPSEM) and liquid-phase transmission electron microscopy (LPTEM).
• Real-time observation of pitting corrosion in pure aluminum thin films under galvanostatic conditions in a saline environment.
• Analysis of pit morphology and identification of gaseous products at the corrosion front.

Main Results:

• Localized corrosion initiated with the formation of blisters alongside nanosized pits.
• Pit morphology evolved from round to fractal-like shapes with increasing current density.
• Molecular hydrogen gas was confirmed to be produced at the corrosion front.
• Gas bubble formation was more pronounced at higher currents.

Conclusions:

• The study elucidates the kinetic mechanism governing the early stages of localized anodic corrosion in aluminum.
• The findings provide insights into the transition of pit morphologies during corrosion progression.
• The identification of molecular hydrogen as a byproduct offers a deeper understanding of the corrosion process.
• This research may inform the development of new descriptors for corrosion resistance in metallic materials.