Simultaneous enhance of the thermal shock resistance and slag-penetration resistance for tundish flow-control refractories: The role of microporous magnesia

As the low thermal shock and slag-penetration resistance of the magnesia castables cause the premature failure of tundish flow-control devices leading to the pollution of steel, the microporous magnesia with high closed porosity and intergranular CaZrO3 phase was utilized for simultaneously enhancing the high-temperature performance. The thermomechanical stress and slag corrosion tests indicated that since the micro-closed pores effectively relieved the thermal stress and CaZrO3 absorbed massive crack-propagation energy, the cold modulus of rupture and residual strength ratio respectively reached 14.4 MPa and 73.4% after thermal shock cycles, nearly half higher than that of the fused magnesia based castables. Meanwhile, the synergistic effect of micro closed pores and intergranular CaZrO3 phase significantly reduced the slag-wettability, improved the interfacial energy and dihedral angle, leading to the decline of slag penetration indice (decreased by-34.8%). This study suggests a potential approach to generate new magnesia based castables in tundish for making clean steel.

Automated summary

This study utilized microporous magnesia to improve the high-temperature performance of magnesia castables, which provides a potential approach for making clean steel in tundish.