Thermodynamics‐Guided Design of Glass‐Rich Mullite Refractories With Enhanced Resistance to Molten Na‐Salts Corrosion

ABSTRACT This study employed thermodynamic simulations to elucidate the sodium corrosion mechanisms of the Al 2 O 3 ‐SiO 2 refractories. The simulation predicted that to inhibit the formation of high‐expansion phases such as NaAlO 2 , NaAlSiO 4 , and NaAl 11 O 17 and to promote the generation of a suitable liquid phase with high viscosity, the optimal chemical composition for Al 2 O 3 ‐SiO 2 refractories should be within the range of 50–70 wt.% SiO 2 and 30–50 wt.% Al 2 O 3 . Based on the simulation results, four raw materials, tabular alumina (TA), mullite grade M70, mullite grade M60, and glass‐rich mullite (GRM), were selected to fabricate five castables (CTA, CTACr, CTAM60, CM70, and CGRM). These castables were experimentally evaluated to validate the thermodynamic predictions, with particular emphasis on the corrosion mechanism of CGRM. Sodium corrosion test verified that CGRM, with low Al 2 O 3 content, exhibited superior resistance to alkali penetration compared to the other three castables. The enhanced resistance is attributed to the early formation of a liquid phase at 729°C, resulting from the reaction between the high‐SiO 2 glass phase and Na 2 CO 3 , thereby effectively inhibiting the penetration of molten sodium salts. The extensive in situ generation of a viscous liquid phase acted as a protective barrier, significantly mitigating sodium corrosion and penetration, thereby endowing CGRM with exceptional corrosion resistance in high‐sodium environments.