Electrophoretic Deposition (EPD): Mechanisms, Kinetics, and Application to Ceramics

TLDR

EPD mechanisms are discussed, their shortcomings identified, and a critique of applying EPD to ceramic shapes and coatings is presented. The study develops a method to determine the Hamaker constant of suspended particles by modeling particle interaction energy and suspension stability, and proposes a DLVO‑based deposition mechanism involving double‑layer distortion under a dc field. Kinetics of constant‑current and constant‑voltage EPD are analyzed, a three‑probe dc technique maps the electrode voltage profile to explain observed voltage drop discrepancies, and kinetic equations derived from mass balance are verified experimentally. The voltage‑profile mapping explains the discrepancy between calculated and experimentally observed voltage drops, and the derived kinetic equations for constant‑current and constant‑voltage EPD are experimentally validated.

Abstract

The mechanisms of electrophoretic deposition (EPD) are discussed and their shortcomings identified. The kinetics of the processes involved are analyzed for constant‐current and constant‐voltage conditions. A method of determining the Hamaker constant of suspended particles is developed by modeling the relationship between the particle inter‐action energy and the suspension stability. A three‐probe dc technique is used to map the voltage profile around the depositing electrode, and the results are used to explain discrepancies between the calculated and experimentally observed voltage drops during deposition. A mechanism of deposition is proposed based on DLVO theory and particle double‐layer distortion/thinning on application of a dc field to the suspension. Kinetic equations are developed for constant‐current and constant‐voltage EPD using mass balance conditions; these are verified by experiments. After the phenomenon is introduced and discussed, a critique of the application of EPD to the synthesis of ceramic shapes and coatings is given.