Sintering effects related to filtration properties of porous continuously gradient ceramic structures

A single-step processing method has been previously established to prepare porous alumina microstructures by a controlled sedimentation technique wher eby fine powder from an aqueous suspension consolidates over a casting slab . Metastable surface chemical control of the suspension properties was able to produce a highly porous flat disc structure with a continuously increas ing mean pore size from top to bottom. Formation of this gradient structure was facilitated by using a relatively broad particle size distribution, To p layer pore sizes less than 50 nm have been achieved. Without modification , these structures are suitable for use as ultrafiltration media, The present work presents a comparison of properties and performance data f or samples made with the above mentioned functionally gradient characterist ics, to samples made with a more uniform microstructure. The effects of sin tering time and temperature were analysed in view of overall porosity, pore size distribution and the extent of densification from the green state. Th ese results are presented along with permeation measurements from a filtrat ion test module. Crown Copyright (C) 2001 Published by Elsevier Science B.V , All rights reserved.