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

Abstract 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 NH 4 Cl 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.