Diphasic monolithic mullite gel of stoichiometric composition shows a multiple aggregation of colloidal SiO2 (∼ 12 nm) and AlOOH (∼10 nm) particles. The identity of the colloidal particles is retained up to the crystallization of mullite at a temperature of 1240°C in unpressed or 1220°C in gels cold-isostatically pressed at 1.5 GPa. Intensive sintering is closely followed by crystallization of mullite. Both sintering and crystallization are apparently related with the formation of a silica continuum. Nucleation of mullite appears to occur at points of contact (interface) of SiO2/δ-Al2O3 particles.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering