Gel-casting without de-airing process using silica sol as a binder

This work reports a gel-casting technology without de-airing process developed to prepare mullite-based ceramics green body using silica sol as a binder. Concentrated alumina slurry dispersed in silica sol with high solid volume loading but low viscosity was successfully prepared at about pH 9.5. In-situ consolidation of the slurry was realized through adjustment of NH4Cl concentration to control the gelation time of the slurry. High compaction and uniform green body without air entrapped was obtained by gel-casting technology without de-airing process, and dense complex-shaped mullite-based ceramics were produced through the new gel-casting system. (c) 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved.