EFFECT OF PRESSURE ON ALPHA-ALUMINA NUCLEATION IN BOEHMITE GEL

The intensity of alpha-Al2O3 nucleation, in seeded as well as unseeded monolithic boehmite-derived alumina gel, increases after isostatic co ld pressing at 1000 and 1500 MPa. In unseeded gels, a general increase in particle coordination induced by the pressure results in a rise in the number of potential nucleation sites. In seeded gels, a heterogen eous nucleation of alpha-Al2O3, which takes place on the contact surfa ce of the (gamma, delta, theta)-Al2O3 particles with a seed, is a func tion of the number of these contacts and the pressure applied.