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Synthesis and Properties of CaAl 2 O 4 ‐Coated AI 2 O 3 Microcomposite Powders
Author(s) -
Desai Priyadarshi G.,
Xu Zhengkui,
Lewis Jennifer A.
Publication year - 1995
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.1151-2916.1995.tb09059.x
Subject(s) - calcination , materials science , decomposition , transmission electron microscopy , mineralogy , scanning electron microscope , inert , chemical engineering , phase (matter) , analytical chemistry (journal) , composite material , chemistry , nanotechnology , catalysis , organic chemistry , engineering , biochemistry , chromatography
Novel microcomposite powders, consisting of inert cores (αAL‐Al 2 O 3 ) surrounded by reactive cement‐based coatings (CaAl 2 O 4 ), were synthesized by a modified Pechini process. The evolution of the crystalline CaAl 2 O 4 phase during calcination was studied using multiple analytical techniques, including DRIFTS, 13 C and 27 AlMAS FT‐NMR, and XRD, for both pure CaAl 2 O 4 and CaAl 2 O 4 ‐coated Al 2 O 3 precursor powders. In both powders, decomposition proceeded via hydrocarbon chain scission and removal of ester groups at low temperatures ( T < 450°C), followed by the formation of inorganic carbonates at higher temperatures ( T > 450°C). These decomposition processes were accelerated by the underlying Al 2 O 3 cores. Transmission electron microscopy (TEM) of the fully calcined powders showed that the inert αAL‐Al 2 O 3 particles were surrounded by relatively uniform CaAl 2 O 4 coatings ranging in thickness from approximately 10 to 100 nm.