Special features of the structure of modifier of periclase­spinel materials with an increased thermal shock resistance

Abstract

The main requirement for periclase­spinel refractories during their operation is the ability to multiple thermal cycling, which can lead to thermal absorption of stress in the refractory system. Therefore, resistance to thermal shocks is considered one of the key properties of the material for extending the service life of linings based on them. The structure of the modifier, which is included in the composition of periclase spinel materials, was investigated using X­ray phase and electron microscopic studies, and the influence of its structural features on the performance characteristics of the refractory was substantiated. The structural and phase features of the modifier were revealed, namely, polyphasic and the presence of metastable phases in the composition of the material, which is due to the presence of impurities and their easy ability to form orthosilicates and crystallize during cooling of the fired sample of the modifier, as well as the oxidizing gaseous firing medium due to the partial transition FeO → Fe2O3 with the formation of a pseudobrookite phase and magnesium ferrite, have a positive effect on the heat resistance of the modified periclase spinel material due to the branching of thermodynamic paths of structural and phase changes in the composition of the refractory in the heating—cooling cycles.