Preparation and properties of MgAl2O4 based ceramics reinforced with rod-like microcrystallines by co-doping Sm2O3 and La2O3

A rod-like microcrystalline reinforced MgAl2O4 (MA) based ceramic with high strength and good thermal shock resistance has been successfully prepared by co-doping Sm2O3 and La2O3 via a single-stage solid-state reaction sintering (SRS) process. The effects of addition amounts of Sm2O3 and La2O3 on the phase compositions, microstructures, shrinkage ratio, apparent porosity, bulk density, high temperature compressive strength and thermal shock resistance of the MA based ceramics have been investigated. The results showed that MA, SmAlO3, La10Al4O21, Sm4.67(SiO4)3O and La4.67(SiO4)3O phases could be found in the ceramics after co-doping additives. The new formed rare earth compounds could prevent the growth of MA grains leading to a densification microstructure of the MA based ceramics. The Sm4.67(SiO4)3O and La4.67(SiO4)3O were formed by the reaction between additives and impurities of raw materials, which presented as rod-like microcrystallines to effectively clean the impurities in the grain boundaries of the MA based ceramics. Accordingly, the sintering properties, high temperature compressive strength and thermal shock resistance of the MA based ceramics were improved markedly.