Effect of Eu₂O₃ on sintering properties and resistance to slag wetting and penetration of MgO-MgAl₂O₄ refractory materials

Alkaline slag is vital in rare earth steel refining, making it crucial to study the wetting and penetration mechanisms between refractory materials and slag. The effect of Eu₂O₃ doping on the sintering properties of MgO-MgAl₂O₄ refractory materials was investigated while simulating the wetting behavior between the refractory and the CaO-Al₂O₃-SiO₂-MgO quaternary alkaline slag during rare earth steel smelting to improve the material’s resistance to alkaline slag corrosion. The doping of Eu₂O₃ can alter the crystal structure parameters of MgAl₂O₄ and MgO, causing lattice distortion. This lattice activation promotes interionic mass and diffusion, helping reduce porosity and promote densification of the material, further improving sintering properties. At the equilibrium wetting temperature (1723 K), Eu₂O₃ doping increases the interfacial free energy between the slag and refractory material, reducing the spreading coefficient of the molten slag. The contact angle increases from 32.1° to 42.2°, and the residual slag volume increases from 17.9% to 23.5%. The results of thermodynamic analysis show that MgAl₂O₄ and EuAlO₃ formed at the interface block the penetration of molten slag at high temperatures, improving the resistance of MgO-MgAl₂O₄ refractories to alkaline slag corrosion. Based on the capillary theory model, it was calculated that the capillary tension of the slag gradually increases with the addition of Eu₂O₃, while the theoretical penetration depth of the slag gradually decreases. The experimental results showed that the slag erosion depth of the sample decreased from 102.54 to 68.28 μm.