Corrosion mechanism of reactive MgO‐bonded Cr2O3‐bearing castables in CaO–Al2O3–Fe2O3–SiO2‐based steel‐making slag

Abstract

AbstractTo assess the feasibility of the reactive MgO (RM) binder in preparing Cr2O3‐bearing castables, the degradation behavior of RM‐bonded Cr2O3‐bearing castables in CaO–Al2O3–Fe2O3–SiO2‐based steel‐making slag was investigated at 1600°C via refractory cup testing. The corrosion resistance and infiltration resistance of RM‐bonded castables were compared with hydratable alumina (HA)‐bonded and calcium aluminate cement (CAC)‐bonded castables with respect to the differences in phase composition and microstructure. Al2O3 grains in RM‐bonded castable were preferentially attacked by the slag compared with Mg(Al, Cr)2O4 spinel‐based matrix. The formation of spinel‐based and CaO·6Al2O3‐based solid solutions with volume expansion from slag/castable interactions suppressed slag infiltration into RM‐bonded castable matrix. Both experimental observations and thermodynamic calculations indicated that the in situ formed Mg(Al, Cr)2O4 spinel in RM‐bonded castables was the predominant reason leading to the superior slag corrosion resistance and infiltration resistance compared with HA‐bonded and CAC‐bonded Cr2O3‐bearing castables.