Jl. Mcardle et Gl. Messing, TRANSFORMATION, MICROSTRUCTURE DEVELOPMENT, AND DENSIFICATION IN ALPHA-FE2O3-SEEDED BOEHMITE-DERIVED ALUMINA, Journal of the American Ceramic Society, 76(1), 1993, pp. 214-222
Addition of alpha-Fe2O3 seed particles to alkoxide-derived boehmite so
ls resulted in a 10-fold increase in isothermal rate constants for the
transformatiou of gamma- to alpha-Al2O3. Changes in porosity and surf
ace area with sintering temperature showed no effect of seeding on coa
rsening of the transition alumina gels, but the 200-fold decrease in s
urface area associated with transformation to alpha-Al2O3 occurred alm
ost-equal-to 100-degrees-C lower in seeded gels compared with unseeded
materials. As a result of high nucleation frequency and reduced micro
structure coarsening, fully transformed seeded alumina retained specif
ic surface areas >22 m2/g and exhibited narrow pore size distributions
, permitting development of fully dense, submicrometer alpha-Al2O3 at
almost-equal-to 1200-degrees-C.