| 摘要 |
The invention disclosed is a self-supporting porous ceramic material, which is typically used in ceramic filters as a substrate prior to coating with a thin dense membrane layer of additional ceramic material. Conventional ceramic support structures are not necessarily designed as membrane support substrates. They are typically made with monosized particles and have a uniform cross section. The present support structure is made via a polydisperse slurry method where a functionally gradient structure is achieved by a colloidal destabilization technique. The key for achieving this structure is to colloidally unstable or metastable suspensions of a controlled and broad particle size distribution, so that segregation based on particle diameter will occur during consolidation. This produces a continuously finer mean particle diameter axial profile from one major surface to the other on the cross section of the consolidated structure. The particle size distribution control is achieved by blending different ceramic powders. In terms of volume fraction, the continuous particle size distribution of the powder used to make the suspension is preferably coarse-rich. |
