Possible improvements of alumina–magnesia castable by lightweight microporous aggregates

This paper focuses on the properties of lightweight alumina–magnesia castable prepared with homemade microporous corundum aggregate, as well as on the investigation of the effects due to the introduction of microporous corundum aggregate on alumina–magnesia castable. The results showed that, in comparison to common alumina–magnesia castable, due to the small pore size and low apparent porosity of microporous corundum aggregate, its introduction leads to an improvement in volume stability, strength, heat insulation and thermal shock resistance of alumina–magnesia castable. The slag resistance of lightweight alumina–magnesia castable is significantly better than that of common alumina–magnesia castable. Microstructure and energy dispersive analyses show that the formation of conically crystallizing CA2 and CA6 is the main reason for the difference in slag resistance. The conical crystals, interlaced and distributed around the aggregate, prevent the sample from further corrosion and penetration of the slag. In addition, since the CaO content of the slag is largely absorbed by the refractory, the viscosity of slag increases, and a solidified layer is formed and adhered on the hot face of sample, thus further deterring the penetration of the slag.