THE INFLUENCE OF WATER-VAPOR ON THERMAL TRANSFORMATIONS OF BOEHMITE

Boehmite compacts and boehmite gels (seeded and unseeded) were annealed at various temperatures in nitrogen and 1 atm water vapor to determine the influence of water vapor on boehmite transformation to new phases, changes in porosity, and morphology. Water vapor was found to accelerate the phase transformations markedly compared to dry N2 treatment. The catalyzing effect of water vapor may be due to its interactions on grain surfaces and generation of fast diffusion paths, resulting in nucleation and growth of new phases. This result shows that control of the furnace atmosphere is a useful variable in thermally activated processes.