Effect of the Addition of Sm2O3 on the Sintering of MgAl2O4 from a Preceramic Al,Mg Oligomer

The preceramic oligomer organomagnesiumoxanealumoxane was synthesized by the co-condensation of organoaluminoxane and magnesium acetylacetonate. Powders of magnesium aluminate spinel (MAS) were obtained by the pyrolysis of the oligomer at 700 and 1250°C. The effect of the pyrolysis temperature on the physicochemical and rheological properties of the powder was studied. With increasing pyrolysis temperature, the particle shape becomes closer to isometric, which leads to a decrease in the limiting length of the linear portion of the compaction curves. A MAS powder containing 3 wt % Sm2O3 was produced to study the effect of the sintering additive. The sintering kinetics was investigated by dilatometry, and the effect of the sintering additive Sm2O3 on the process and the mass-transfer mechanism during the sintering of spinel was estimated. According to the quantitative analysis data, the activation energies for the pure MAS and the MAS doped with Sm2O3 are Q1250 = 481 kJ/mol and QSm2O3 = 775 kJ/mol, respectively. The sintering additive does not affect the mass-transfer mechanism; however, it increases the activation energy by 60%, doubles the shrinkage, and decreases the temperature of the beginning of sintering from 1546 to 1494°C.