Formation mechanism of MgSrAl10O17 and its effect on the mechanical performance of lightweight Al2O3-MgAl2O4 refractories

Lightweight Al2O3-MgAl2O4 refractories can be achieved by producing a density gradient structure which guarantees good slag resistance and low thermal conductivity. To further improve the mechanical properties of this material, in this study, in situ platelike structure was developed by adding different amounts of SrCO3 in the matrix. The phase composition, microstructure, physical and mechanical properties of the obtained lightweight refractories were characterized and evaluated. The results showed that besides corundum and spinel, platelike MgSrAl10O17 phase was also formed during reactive sintering. The well-developed MgSrAl10O17 phase possessing an interlocking structure formed grain-grain bridging with MgAl2O4, which significantly improved the mechanical performance of lightweight Al2O3-MgAl2O4 refractories. Although no obvious changes occurred in apparent porosity and bulk density of the specimen, the compressive strength and refractoriness under load were significantly improved after SrCO3 addition, which increased from similar to 50 MPa to similar to 80 MPa and 1589 degrees C-1656 degrees C, respectively. To better understand the relationship between microstructure evolution and improvement in performance, the formation mechanism of the MgSrAl10O17 phase and its reinforcement mechanism in the material were described in detail.