Sintering of transient Al2O3 phases in monolithic gels

The sintering of transient alumina phases in boehmite derived alumina gels was carried out under static thermal conditions (at sintering temperatures between 1075-1225 degrees C) and under dynamic thermal conditions (in temperature range approximately 800-1200 degrees C). At a low heating rate (2-10 degrees C/min) the sintering of transient Al2O3 phases could be modeled by grain boundary and simultaneous bulk diffusion with activation energies 323 kJ/mol and 511 kJ/mol, respectively. At rapid heating the sintering kinetics is probably affected also by the remaining water escape. It can cause particle rearrangement in the first stage of sintering. Weight loss experiments were used to determine the amount of water escaped during sintering.