Ab Initio Molecular Dynamics Study of CMAS Slag–MgO Interfaces: Crystal Orientation Effects and Corrosion Mechanisms

ABSTRACT MgO‐based refractories, known for their high refractoriness, strong resistance to basic slags, and excellent thermal stability, are widely used as lining materials in the metallurgical industry, particularly in steelmaking. However, the interaction mechanisms between CaO–MgO–Al 2 O 3 –SiO 2 (CMAS) slag and MgO at high temperature remain complex and are not fully understood. In this study, ab initio molecular dynamics (AIMD) simulations were employed to investigate the atomic‐scale interaction mechanisms between CMAS slag and MgO surfaces with different crystallographic orientations. The results reveal that while MgO(100) and MgO(110) surfaces exhibit weak interfacial bonding and limited atomic diffusion, the MgO(111) surface undergoes pronounced atomic interdiffusion and bidirectional charge transfer, resulting in the highest interfacial interaction energy (8.67 J·m − 2 ). The dynamic balance between the stabilizing covalent network of Al‐O bonds (which inhibits diffusion) and the ionic redistribution of Ca/Mg (which promotes melting) is the critical factor determining the material's corrosion resistance. The findings provide a theoretical basis for optimizing the CMAS/MgO interfacial stability, thus providing guidance for improving the high‐temperature performance and corrosion resistance of MgO‐based refractories.