Preparation of Porous RBSN Ceramics with Uni-directionally Aligned Channels by an Ice-Templating Method

Abstract

Porous ceramics are widely used for applications such as catalysis supports, gas distributors and filters such as DPF. For these purpose, it is important to have proper porosity controlling pore structure while maintaining mechanical and thermal properties. In this work, we have prepared the porous ceramic structures made of reaction bonded silicon nitride with hierarchical pore structures. Uni-directionally aligned porous channels, which are mostly filled with β-Si3N4 whiskers, were achieved by ice-templating method. The multi-layered lamellar structures of the walls are controllable by the processing conditions, such as solid concentration, freezing rate and additives. We have investigated and characterize the influences of the conditions on the microstructures and the properties, porosity, pore size distribution, lamellar thickness, wavelength, and orientations. The compressive strength test and flow test was performed to determine the structural integrity and filterability.