Enhanced slag resistance of magnesia refractory castables with addition of BaSO4

The present study aims to clarify the influence of BaSO 4 on composition, microstructural evolution and properties of magnesia refractory castables. Castables with different BaSO 4 contents were prepared using calcined magnesia, microsilica , and BaSO 4 as raw materials. The results show that introducing BaSO 4 can significantly enhance slag resistance of magnesia refractory castables. Castables presented high compactness and mechanical properties with 0–3 wt% BaSO 4 for the liquid sintering process and formation of BaMgSiO 4 at high temperature. Then compactness of castables decreased when BaSO 4 content increased from 5 wt% to 10 wt% for its decomposition and a subsequent increase in the pore content. BaSO 4 presented minor effects on the low temperature (1100 °C) structure of castables and played an important role in enhancing high temperature slag resistance, owing to its high structural stability till 1550 °C. The slag resistance mechanism of castables with BaSO 4 is that Al 3+ in slag was incorporated into periclase intergranular to form BaAl 2 O 4 phases during corrosion process, resulting in the increased slag viscosity and suppressed continuing penetration. The research of this work provides a new insight into microstructure and properties enhancement of magnesia refractory castables used in metallurgical field.