Transactions of the INDIAN CERAMIC SOCIETY Vol. 73 2014
Effect of Fuel Concentration on the Properties of
Combustion Synthesized MgAl2O4 Spinel Powders
Abhisek Choudhary1, K. Rajeswari, Y. S. Rao and Roy Johnson*
Pages : 303-306
DOI : 10.1080/0371750X.2014.943911
Abstract
Stoichiometric solution of aluminium nitrate and magnesium nitrate along with 4.66 to 7.66 moles of urea (fuel)
concentrations were prepared and heated slowly to evaporate the water till a homogeneous gel was formed. Critical
temperatures for the formation of MgAl2O4 spinel were identified using TG/DSC analysis of the gel and the reaction
mixture was introduced into the resistive heating furnace preheated at 350oC. Powder mass thus obtained was
characterized and was calcined at 1000oC for removal of retained carbon and crystallization. The powder was
further characterized for phase purity, powder morphology, particle size and BET surface area. A fuel concentration
beyond 6.66 moles generated excess gases resulting from the decomposition of unreacted urea which got occluded
in the foamy combustible mixture. On reaching the self-ignition temperature, combustion occured and the sudden
escape of these gases led to highly porous, fragile fluffy mass. Surface area and sinterability of the powder showed a
clear correlation with the fuel concentration in the reaction mixture. Spark plasma sintered samples in comparison
to the conventional sintered samples exhibited enhanced density values with finer grain sizes.
