Enhanced slag resistance and mechanical properties of magnesia castables with strontium carbonate addition

Magnesia castables have been widely used in metallurgical industries with the advantages of high refractoriness, non-polluting steel, and resistance to alkaline slag. Magnesia castables were prepared using strontium carbonate (SrCO3) as additive to enhance slag resistance and mechanical properties, and the influence of SrCO3 on the evolution of phases, microstructure and properties of magnesia castables sintered at different temperatures was clarified. The results show that, with the introduction of SrCO3 (lower than 3 wt.%), elastic modulus, mechanical strength, thermal shock resistance and densification of magnesia castables were significantly enhanced owing to the formation of needle-like Ca0.9Sr0.1MgSi2O6 phase and liquid phase when sintering at high temperatures, and the introduced SrCO3 presented minor effects on the mechanical properties of castables for its highly structural stability below 1100 °C. During the slag corrosion process, SrCO3 and SiO2 in castables reacted with Al3+ in molten slag to form SrAl2SiO8 phase, resulting in the increased slag viscosity and suppressed continuing penetration.