Electrophoretic deposition of thick titania coatings at constant voltage by controlling current density

Abstract

AbstractKinetics of electrophoretic deposition (EPD) process usually slows down with time due to the reduction in effective electric field (Eeff) across the suspension. So, normally the deposition of thick coatings or 3‐D objects by EPD is not possible at low voltages. The suspensions of nanometer (NT) and micrometer (MT)‐sized titania particles were prepared in isopropanol, using triethanolamine (TEA) plus acetic acid (AA) as the charging additives. Eeff is directly proportional to the current density. It was found that depending on the composition of suspensions, the current density and so Eeff decrease, remain constant or increase during EPD from them. Current density increased during EPD from NT suspensions with 0.33 (AA≥1.33 mL/L), 0.66 (AA≥2 mL/L) and 1.33 mL/L (AA≥6.66 mL/L) TEA. However, it did not increase any of the MT suspensions, but remained nearly constant for those with 0.33 and 0.66 mL/L TEA plus AA>1.33 mL/L and AA>2 mL/L, respectively. Current density increased or remained constant during EPD from the suspensions in which majority of H+TEA ions are adsorbed on the particles surface and the zeta potential of particles is below the critical value in them (NT≈70 mV and MT≈60 mV). Deposition rate increased continuously during EPD from the suspensions in which current density increased for them.