Ab Initio Molecular Dynamics Study of C₃S/CaO and C₂S/CaO Interfaces: Crystal Orientation Effects and Corrosion Mechanisms

ABSTRACT: MgO–CaO refractories exhibit significant potential in the cement industry owing to their excellent refractoriness, robust resistance to alkaline corrosion, superior coating adherence, and high thermodynamic stability. Nevertheless, the intricate interfacial interaction mechanisms between these refractories and cement clinker at high temperature remain poorly understood. In this study, ab initio molecular dynamics (AIMD) simulations were employed to investigate the interactions between various crystallographic surfaces of CaO and the two primary mineral phases of cement clinker (tricalcium silicate, C₃S, and dicalcium silicate, C₂S). The results demonstrate that the CaO(100) surface maintained interfacial structural stability through ordered coordination and minimal charge transfer. Conversely, the CaO(111) surface exhibits high interfacial reactivity and surface degradation, driven by its unstable surface structure and strong interfacial polarization effects. The interfacial reactivity of the CaO(110) surface is intermediate, suggesting that preferential exposure of the CaO(110) surface may improve the kiln coating performance of the refractory, nevertheless, this implication remains a theoretical prediction and requires further experimental validation. These findings offer fundamental atomic-scale insights for the optimization of MgO–CaO refractories in industrial cement production.