SYNTHESIS OF γ- ALUMINA BY SOLUTION COMBUSTION METHOD USING MIXED FUEL APPROACH (UREA+GLYCINE FUEL)

Nano crystalline γ-Alumina powders were synthesized by Solution Combustion reaction between aluminium nitrate as oxidizer and a mixture of urea and glycine fuel as reducer. In this fuel mixture, urea was taken as stoichiometric fuel and glycine was added as excess fuel to alter the exothermicity of redox reaction between aluminium nitrate and urea. The ratio of urea to glycine had been optimized to obtain single phase gamma alumina. A Multi channel thermocouple setup was used to measure the flame temperatures to study the nature of combustion of various fuel mixtures. The variation of adiabatic flame temperature was calculated theoretically for different urea/glycine mixture ratios according to thermodynamic concept and correlated with the observed flame temperatures. These powders were characterized by XRD, SEM, showing that the powders were composed of polycrystalline oxides with crystallite size of 81 nm for alpha alumina, ~ 5 nm for gamma alumina and having highly porous microstructure. An interpretation based on maximum combustion temperature and the amount of gases produced during reaction for various urea to glycine ratio composition had been proposed for the nature of combustion and its correlation with the characteristics of as synthesized powder