Transformation kinetics of θ- to α-phase of alumina powders prepared from different alumina salts by chemical processing

The aim of this study was to produce nanosized alumina powders from two different aluminum salts (AlCl 3 and AlNO 3 .9H 2 O) by precipitation method and to investigate transformation kinetics of α-Al 2 O 3 crystallization obtained from quantitative DTA curves via Kissinger–Akahira–Sunose (KAS) metho...

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Bibliographic Details
Published in:Journal of thermal analysis and calorimetry 2016-08, Vol.125 (2), p.645-649
Main Authors: Ipek, Mediha, Toplan, Nil, Toplan, H. Ozkan
Format: Article
Language:English
Subjects:
Activation energy
Aluminum oxide
Analytical Chemistry
Chemistry
Chemistry and Materials Science
Inorganic Chemistry
Measurement Science and Instrumentation
Physical Chemistry
Polymer Sciences
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Summary:The aim of this study was to produce nanosized alumina powders from two different aluminum salts (AlCl 3 and AlNO 3 .9H 2 O) by precipitation method and to investigate transformation kinetics of α-Al 2 O 3 crystallization obtained from quantitative DTA curves via Kissinger–Akahira–Sunose (KAS) method. Precipitates are dried at 80 °C for 24 h and then calcinated at 1200 and 1300 °C for 1 h. Dried powders have bayerite [Al(OH) 3 ] and calcinated powders have theta- (θ) and alpha (α)-alumina phases which confirmed by XRD analysis, and the crystallite size of powders determined by Scherrer equation is about 30 nm for dried powders and ranged from approximately 15–35 nm for calcinated powders. Scanning electron microscopy studies revealed that the morphology and size of powders precipitated from two different salts are similar to each other, and powders contain mainly sub-micrometer-sized particles and close to spherical form. Activation energy values determined by KAS equation range from 717 to 411 kJ mol −1 for powders produced from aluminum nitrate salt and from 844 to 476 kJ mol −1 for powders produced from aluminum chloride salt depending on the transformation rate.
ISSN:1388-6150
1588-2926
DOI:10.1007/s10973-016-5410-1