Enhanced thermal shock resistance in magnesia refractories through in situ formation of CaO·2La ₂ O ₃ ·3SiO ₂

Abstract Magnesia refractories have been widely utilized in industries such as steel, nonferrous metallurgy, and cement. However, their application has been limited due to their inadequate thermal shock resistance. This study examines the effect of club‐shaped CaO·2La 2 O 3 ·3SiO 2 crystals formed in situ on the thermal shock resistance of magnesia refractories. The results demonstrate that CaO·2La 2 O 3 ·3SiO 2 grains, which possess a high melting point, replace monticellite CaO·MgO·SiO 2 (CMS) grains with a low melting point in magnesia refractories. The crystal growth of CaO·2La 2 O 3 ·3SiO 2 follows a two‐dimensional nucleation growth mechanism, characterized by stepped growth stripes. Furthermore, the microstructure of magnesia refractories is modified through the formation of club‐shaped CaO·2La 2 O 3 ·3SiO 2 grains located at the grain boundaries, resulting in enhanced thermal shock resistance. The in situ formation of CaO·2La 2 O 3 ·3SiO 2 actively contributes to the toughening of magnesia refractories by increasing their resistance to crack propagation. Overall, this research highlights the beneficial role of in situ formed CaO·2La 2 O 3 ·3SiO 2 crystals in improving the thermal shock resistance of magnesia refractories.