Interfacial Reactions Between Ce-Bearing Steels and a MgO-C Refractory

In the current study, the effect of cerium content in the steel on the interfacial reaction between the steel and the MgO–C refractory was investigated in laboratory experiments by immersing MgO–C refractory bars into the molten steel. The morphology and chemical composition of reaction products at the interface and inclusions in the steel were analyzed using a scanning electron microscope (SEM) as well as an energy dispersive spectrum (EDS). When there was no cerium in the steel, the reaction product at the steel-refractory interface was mainly MgO due to the reaction between the magnesium vapor and CO at the interface. When the addition content of cerium was 0.02 and 0.1 wt pct, a Ce₂O₂S layer was generated at the interface by the reaction between the dissolved sulfur and cerium and the MgO refractory. With 0.5 wt pct cerium in the steel, the dissolved sulfur was mostly consumed to form CeS and Ce₂O₂S inclusions, leading to the generation of a double-layer reaction product of CeAlO₃ and Ce₂O₃ at the interface, and the CeAlO₃ was in the refractory side while the Ce₂O₃ was in the molten steel side. As the content of cerium in the molten steel increased, the erosion of the MgO–C refractory by the steel significantly increased, causing more foreign inclusions into the steel. The consumption of cerium by the steel-refractory reaction led to a significant variation in the composition of cerium-bearing inclusions. Thermodynamic calculation was consistent with the experimental result.