High-temperature tensile strength of alumina-spinel refractory by Brazilian test at 1200oC coupled with DIC in-situ monitoring

This study investigated for the first time the corrosion effect of Al2O3-MgAl2O4 refractory by steel ladle slag using a DIC-coupled Brazilian test at 1200oC. Three types of alumina-spinel materials were used in the test, namely, original non-infiltrated refractory, slag-infiltrated at 1450oC as well as postmortem refractory after 69 cycles of work in the sidewalls of steel ladle. Lab infiltration was conducted at 1450oC using CaO-Al2O3-SiO2-based ladle slag and its analog enriched with manganese (10% MnO). The tensile strength of postmortem material at 1200oC was the highest at 10.7MPa, and it was 50% and 70% higher than for reference and MnO-enriched slag, respectively, and 80% higher than for original refractory. The significantly raised tensile strength of slag-infiltrated materials vs. original non-infiltrated brick was directly related to the densification of microstructure by corrosion products (mainly CA6, CA2, Fe) which caused the infiltrated materials to be stiffer and with a more brittle nature to fracture.