Enhanced slag resistance of magnesia refractory castables with addition of BaSO4

Abstract

The present study aims to clarify the influence of BaSO4 on composition, microstructural evolution and properties of magnesia refractory castables. Castables with different BaSO4 contents were prepared using calcined magnesia, microsilica, and BaSO4 as raw materials. The results show that introducing BaSO4 can significantly enhance slag resistance of magnesia refractory castables. Castables presented high compactness and mechanical properties with 0–3 wt% BaSO4 for the liquid sintering process and formation of BaMgSiO4 at high temperature. Then compactness of castables decreased when BaSO4 content increased from 5 wt% to 10 wt% for its decomposition and a subsequent increase in the pore content. BaSO4 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 BaSO4 is that Al3+ in slag was incorporated into periclase intergranular to form BaAl2O4 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.