Microsecond resolution of cavitation bubble dynamics using a high-speed electrochemical impedance approach

Area of Science:

• Electrochemistry
• Materials Science
• Acoustics

Background:

• Ultrasonic cavitation poses challenges in electrochemical systems.
• Understanding cavitation-induced electrode damage is crucial for material integrity.
• Existing methods lack the resolution to capture dynamic cavitation events.

Purpose of the Study:

• To present a new high-resolution method for detecting electrode parameters under ultrasonic cavitation.
• To investigate the dynamic processes of cavitation bubbles near an electrode surface.
• To elucidate the mechanism of erosion-corrosion induced by ultrasonic cavitation.

Main Methods:

• Electrochemical impedance spectroscopy (EIS) with a 500 kHz AC excitation signal.
• Time-resolved detection of electrode impedance (uncompensated resistance, capacitance, Faradaic current).
• Potentiostatic control of an aluminum electrode under ultrasonic cavitation.

Main Results:

• The method achieved a 2-microsecond resolution for detecting impedance changes.
• Observed reduction in capacitance and increase in resistance indicated bubble proximity.
• Bubble collapse correlated with the onset of Faradaic current, confirming erosion-corrosion.

Conclusions:

• The developed method effectively monitors dynamic cavitation processes at electrode surfaces.
• Cavitation bubbles form near the electrode, collapse, and damage the passive film.
• This confirms an erosion-corrosion mechanism initiated by bubble collapse.