Preparation and microstructure regulation of MgO-CaO-Y₂O₃ refractories with enhanced slag resistance

MgO-CaO refractories have attracted much attention in the field of clean steel due to the ability of their internal CaO to adsorb elements such as S and P in molten steel. However, there are still some problems such as difficult sintering and insufficient corrosion resistance existing in this system. Different contents of Y₂O₃ were introduced into MgO-CaO system to prepare MgO-CaO-Y₂O₃ ternary refractories via traditional and induction sintering methods. The influence of microstructural regulation on the slag-resistant properties of the refractories was investigated. The results show that the introduction of Y₂O₃ in the MgO-CaO refractories prepared via the two sintering methods leads to the grain boundary reconstruction effect. Under the condition of traditional sintering, when a smaller amount of Y₂O₃ is introduced into the MgO-CaO refractories, Y₂O₃ is able to activate the lattice, promote sintering, and improve the densification of the refractories. However, when more Y₂O₃ is introduced, the excess Y₂O₃ hinders the sintering densification process. Combined with lamellar intergranular phase generated in the refractories, Y₂O₃-based solid solution can react with the slag, increase the slag viscosity and inhibit the penetration of the slag into the refractories. Under the condition of induction sintering, the solid solution of yttrium ions in CaO is increased by using the coupling of electromagnetic and thermal fields. Compared with the MgO-CaO refractories with high Y₂O₃ content prepared by traditional sintering, the induction sintered refractories have higher densification, which further increases the corrosion resistance. The results provide a new path for developing long-life MgO-CaO based refractories.