Role of Ionic Depletion in Deposition during Electrophoretic Deposition

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Abstract
A model is developed for deposition during the electrophoretic deposition (EPD) process. It suggests that ions that move with the charged particles in suspension are depleted at the depositing electrode, locally changing the pH toward the isoelectric point (pHiep) to give coagulation. The variation of zeta (zeta) potential is modeled via chemical‐equilibrium and surface‐adsorption isotherms. The model successfully fits the experimental data for Al2O3 particles in ethanol when the Freundlich surface‐adsorption isotherm is assumed. Calculations predict the co‐ion concentration gradient as a function of location within the suspension, and the deposition time and its role in the coagulatoin process during EPD.