Electrophoretic deposition forming of porous alumina membranes

Abstract

An electrophoretic deposition (EPD) technique is used to prepare porous alumina membranes. The deposition kinetics which are conventionally derived based on a mass conservation law have been modified in terms of the thickness of the deposited layer. This modification allows the porosity evolution of the membrane to be predicted under a variety of EPD processes. A transition in deposition from linear to parabolic kinetics is observed which has been further verified by a subsequent microstructure examination. The deposited layers are increasingly uniform and dense in structure with increasing deposition time over the parabolic kinetic regime; whilst a more porous packing is observed during the initial deposition time period, corresponding to the linear kinetic regime. The microstructural evolution of the EPD membranes appears to agree well with the porosity equations derived based on an analytical combination of both experimentally-derived formula and the corresponding kinetic model. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.