Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/781
Title: Calcination and associated structural modifications in boehmite and their influence on high temperature densification of alumina
Authors: Padmaja, P N
Ghosh, S K
Warrier, K G K
Keywords: Hydroxides
Diffraction
Identification
Transformation
Transition
Infrared-spectroscopy
Gamma-alumina
Alpha-alumina
Densification
Porosity
Calcination
Sol-gel process
Issue Date: 2011
Publisher: Elsevier
Citation: Ceramics International 37(8):3329-3334;Dec 2011
Abstract: A systematic study is reported on the calcination of boehmite and its associated structural changes, and their effect on densification features. Boehmite precursor gels have been calcined in the temperature range 250-1200 degrees C. The associated structural changes are identified by FTIR and XRD. The specific surface area measurements indicated a relatively high value of 169 m(2)/g for bochmite calcined at 400 degrees C; this value reduced to 4 m(2)/g on calcination at 1200 degrees C. In the temperature range 400-1000 degrees C, the coordination of aluminium changes from a quasioctahedral to a tetrahedral nature, which reverts to octahedral at 1200 degrees C. The precursor containing gamma-alumina gives a 92.1% theoretical density, on sintering at 1500 degrees C due to the highly unstable quasioctahedral coordination. Boehmite precursors calcined at 400 degrees C and 1000 degrees C produced a density of 88.2% and 96.9%, respectively, in the sintered compact at 1500 degrees C. Boehmite calcined to a-alumina (1200 degrees C) possesses an octahedral structure having a density of 97.6% at 1500 degrees C.
URI: http://ir.niist.res.in:8080/jspui/handle/123456789/781
ISSN: 0272-8842
Appears in Collections:2011

Files in This Item:
File Description SizeFormat 
2011_ 0077.pdf819.58 kBAdobe PDFView/Open


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.