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Transition from gravito- to electroconvective regimes in thin-layer electrodeposition
G Gonzalez1, G Marshall, F Molina
1INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires, Argentina.
Summary
Increasing electrolyte viscosity shifts electrochemical deposition from buoyancy-driven to electrically-driven convection. This transition, observed experimentally and predicted theoretically, impacts flow dynamics in ion-containing systems.
Area of Science:
- Physical Chemistry
- Fluid Dynamics
- Electrochemistry
Background:
- Electrochemical deposition involves complex fluid dynamics influenced by gravity and electric fields.
- Understanding the interplay between gravitoconvection and electroconvection is crucial for controlling deposition processes.
Purpose of the Study:
- To analyze the transition between gravitoconvective and electroconvective regimes in thin-layer electrochemical deposition.
- To investigate the effect of electrolyte viscosity on the dominance of these convection types.
Main Methods:
- Experiments were conducted under galvanostatic conditions in convection-prevailing regimes.
- Particle image velocimetry (PIV) was used to measure velocity distributions.
- A theoretical model was developed to analyze the hydrodynamic parameters.
Main Results:
- Low electrolyte viscosity favors buoyancy-driven (gravitoconvective) flow.
- Increasing viscosity enhances electrically-driven (electroconvective) flow, leading to a regime transition.
- The experimental transition was observed at 1.5 times the viscosity of water; the model predicted it at approximately 2 times.
Conclusions:
- Increasing electrolyte viscosity damps gravitoconvection while enhancing electroconvection under galvanostatic conditions.
- Viscosity is a key parameter for controlling the convective regime in electrochemical deposition.
- The findings provide insights into physicochemical hydrodynamic flows involving ions.