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Transformation, Microstructure Development, and Densification in α‐Fe 2 O 3 ‐Seeded Boehmite‐Derived Alumina
Author(s) -
McArdle James L.,
Messing Gary L.
Publication year - 1993
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1993.tb03710.x
Subject(s) - boehmite , seeding , microstructure , materials science , sintering , nucleation , porosity , isothermal process , chemical engineering , alkoxide , mineralogy , metallurgy , composite material , chemistry , thermodynamics , aluminium , catalysis , biochemistry , physics , organic chemistry , engineering
Addition of α‐Fe 2 O 3 seed particles to alkoxide‐derived boehmite sols resulted in a 10‐fold increase in isothermal rate constants for the transformation of γ‐ to α‐Al 2 O 3 . Changes in porosity and surface area with sintering temperature showed no effect of seeding on coarsening of the transition alumina gels, but the 200‐fold decrease in surface area associated with transformation to α‐Al 2 O 3 occurred ∼ 100°C lower in seeded gels compared with unseeded materials. As a result of high nucleation frequency and reduced microstructure coarsening, fully transformed seeded alumina retained specific surface areas >22 m 2 /g and exhibited narrow pore size distributions, permitting development of fully dense, submicrometer α‐Al 2 O 3 at ∼ 1200°C.