以電泳覆膜法製備多孔性氧化鋁陶瓷濾膜

Abstract

本研究是採用電泳覆膜法(Electrophoretic Deposition，EPD )來製備多孔性氧化鋁陶瓷濾膜(Porous Alumina Membrane)。本研究中以覆膜之厚度建立EPD覆膜之動力學，異於以往藉由覆膜之重量推演出動力學之方式。這種以膜厚為主的改進，配合適當EPD製程參數，可使吾人預測所製備之陶瓷濾膜的孔隙度隨覆膜厚之變化情形，進而製備所需之孔隙度及孔隙之大小之濾膜。 由研究中發現，使用EPD來製備多孔性陶瓷濾膜動力學過程中，膜厚會隨著時間從線性關係(t-h linear regime)轉變到拋物線之關係(t-h parabolic regime)。而陶瓷濾膜之孔隙度及孔隙之大小也會伴隨此動力學變化從較不均勻、結構較鬆散且不一致的堆積變為孔隙較均勻、大小較一致之堆積，在研究中從微結構之觀察也證實了此一結果。而且所推導出之孔隙度預測式(porosity equation)也獲得實驗之驗證，也更說明了此式的實用性。此外，EPD製程參數，諸如覆膜時間、覆膜電壓、懸浮液濃度、溫度、粉體粒徑大小對覆膜動力學、堆積之微結構變化及後續之燒結影響均做了有系統之探討。由結果可知，在控制良好的製程條件下，EPD製程確實提供了另一個製備陶瓷濾膜的良好途徑。

In this investigation, an electrophoretic deposition (EPD) technique is used to prepare porous alumina membranes. The deposition kinetics, which is conventionally derived based on a mass conservation law, has 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. Furthermore, the influences of the particle size, suspension concentration and particularly the EPD parameters, e.g. applied dc voltage, deposition time on the microstructure of the as-prepared EPD membrane and the further sintering behaviors were investigated in the work.