Preparation of Nanocrystalline Magnesium Aluminate Spinel Powder by Thermal Explosion Mode of LCS

摘要

The nanocrystalline MgAl_2O_4 powder was prepared by thermal explosion mode of low-temperature combustion synthesis (LCS) using urea as fuel and nitrates as oxidizers. The molar ratio of nitrates to urea and the adiabatic flame temperature was calculated according to the propellant chemistry and combustion thermodynamics theory respectively, and the effect of thermal explosion temperature on the properties of powder was investigated. The phase and morphology of the synthesized powder were investigated by X-ray diffraction and scanning electron microscopy. The results showed that the combustion process completed in very shortly time, and the cauliflower-like powder with porous structure was obtained. The crystalline size of MgAl_2O_4 increased with the increasing of thermal explosion temperature, and the powder had good crystalline shape and purity. The average crystalline size of MgAl_2O_4 prepared at 400°C was approximately 40nm.