The firing steps and phases formed in Mg–Zr–Al refractory dolomite-based materials

Due to the open pore microstructure, MgO–CaZrO3 refractory composites are considered useful materials in various industrial applications. However, the reactivity of the MgO limits its utilization in acid conditions. The chemical inertness and more balanced mechanical properties of MgAl2O4 in comparison with MgO bring forward CaZrO3–MgAl2O4 refractories as promising alternative materials.The present study was carried out in order to determine the feasibility of using Argentine dolomites in the preparation of CaZrO3–MgAl2O4 by solid state reaction. The thermal and structural changes which occur during the firing of the batches up to 1425 °C were studied by the combination of diffractometric and infrared spectroscopic data at the most remarkable reaction steps. The study of phase changes within the investigated thermal range allowed establishing the main differences in the composition of the mixtures in each firing step. According to these results, the final product is composed mainly by MgAl2O4, CaZrO3, and Ca2SiO4 phases and the optimal synthesis temperature would be 1425 °C. According to SEM microscopy, the existence of ceramic bonding between CaZrO3 and MgAl2O4 could be confirmed.