Studies on the control of porous properties in the fabrication of porous supports

In this work, the dry pressing technique for making porous ceramic supports was studied. We used kaoline and alpha-alumina as the ceramic raw materials and polyvinyl alcohol (PVA) as both binder and pore former. The effects of the quantities of PVA, pressing pressure and sintering temperature on the microstructure, i.e. porosity and pore size distribution, were investigated. The properties in terms of permeability and flexural strength of our final products were also measured and related to both processing and microstructure parameters. It was found that the water expulsion method seemed ideal for measuring pore sizes in the ranges of several microns in our samples. The measured pore sizes fit our permeability data and Carman's equation very well. Flexural strength up to 1 MPa was obtained for a porous support with about 40% porosity with an average pore size of 1.5 mu m.