A monolithic colloidal gel of mullite composition, prepared from SiO2
and boehmite sols, was sintered under isothermal conditions. The sinte
ring process was studied by dilatometry, thermogravimetric analysis, b
ulk density measurements and discontinuous shrinkage measurements. The
silica component of stoichiometric colloidal mullite gel prevented cr
ystallization of alpha-Al2O3 in the system. The initial rapid part of
the sintering is controlled by the alumina phase and it is not a visco
us sintering process in the sense of Scherer's viscous sintering model
. The final part of sintering, above approximately, 80% of the theoret
ical density, is controlled by the silica component of the gel and agr
ees very well with the Scherer model.