Year 2006, Volume 26

Abstract

The effect of water treatment of Egyptian fumed silica powder at room temperature and 100 oC on its chemical and phase composition as well as morphology and surface area has been investigated. Selected samples that showed maxima of silica content and surface area were dry-pressed and fired up to 800, 1200 and 1400 oC along with the original untreated sample.The fired samples were investigated for their densification parameters, phase composition, microstructure and pore-size distribution in order to assess their suitability for processing ceramic filters. Results show that the original fumed silica powder may be recommended for processing ceramic filters,The amount and distribution of porosity of the original fumed silica powder fired up to 800 oC may suggest a possible use as a ceramic filter, whereas the ultra fine and pure fumed silica treated by boiling in water for 4 h may be recommended for processing dense, pure and refractory cristobalite and/or mullite bodies.