Slip cast forming of multilayer ceramic filter by fine particles migration

Multilayer ceramic filter was fabricated by fine particle migration occurring during the slip cast compaction of a particulate mix composed of a fine powder and coarse granules. The materials were prepared from the mixture of quartz, natural zeolite and lead borosilicate glass frit. The casting procedure involves the introduction of the powder slurry into a cylindrical shaped mold, allowing it to form a thin filtering layer onto the mold walls. The granules are then added into the mold without settlement of the previously filled slurry. The new casting method leads to a specific interlayer between the granular material and the filtering layer by a fine particle migration phenomenon. Casting, drying and sintering processes of the filters were discussed with respect to two different particle sizes of the powder slurry (δ50 = 0.98 μm and δ50 = 1.82 μm) and with variable solid concentration (5–40% solids by weight). Dilute slurry with relatively coarse size has appropriate condition for the filter fabrication.