Quantitative Assessment of Microporous MgO Castable Erosion and Corrosion Behaviors in Two Tundish Covering Fluxes

Strict requirements on low-carbon and environmentally friendly steelmaking process promote the application of the novel microporous magnesia with excellent thermal insulation as a promising refractory. This study performed static and dynamic slag resistance tests of the microporous magnesia in two tundish covering fluxes to explore its erosion and corrosion behaviors under different conditions. The fused magnesia castable was used as the control group. The phenomena were thoroughly analyzed according to macroscopic and microscopic morphology observations, supplemented with thermodynamic calculation and CFD simulation. The results showed that, castables were severely damaged through wear and peeling in the dynamic slag resistance tests, which process was enhanced by the fast dissolution of MgO. The microporous magnesia possessed stronger slag resistance since its occurrence time for wear was delayed over 5 minutes compared to fused magnesia castable, and the wear rate was lower. In addition, the microporous magnesia was less affected by the dissolution of MgO due to the formation of a spinel layer on the surface, which hindered the slag penetration and mass transfer. Finally, a Sherwood correlation was obtained based on the experimental data, which allowed one to calculate the wear rate of MgO castable at slag line in actual tundish.