Synthesis of aluminomagnesian spinel with excess magnesium oxide under varying flow rates of cation mass transfer

MgAl2O4 with 10 mol% excess of MgO was synthesised by heating a mixture of highly dispersed magnesium and aluminium oxide powders to 800 and 1100 C. The diffusion mass transfer rate of aluminium cations in the synthesis of spinel was accelerated by introducing a TiO2 additive into Al2O3, whereas the mass transfer rate of magnesium cations was delayed by introducing a Na2O additive into MgO. Simultaneously, spinel was synthesised without additives. The products of synthesis were investigated using petrography, X-ray phase analysis, and dissolution in HCl. The use of the additives and increasing the synthesis temperature decrease the solubility of powders in HCl, which facilitates bringing initially formed solid solutions of Al2O3 in MgAl2O4 closer to the composition of stoichiometric spinel. 7 refs.