Effect of micro-sized MgCO3 addition on properties of MgAl2O4 spinel containing castables

Micro-sized MgCO3 was used in castables as the MgO-precursor for generating sub-micro sized MgO and for producing subsequent in-situ magnesium aluminate (MgAl2O4, MA) spinel. The influence of 0-2.0 wt% micro-sized MgCO3 addition on the volumetric stability and thermo-mechanical properties of castables after firing at 1000 °C and 1550 °C was investigated. The in-situ spinel formation and its influence on the microstructure evolution in castable matrices with different micro-sized MgCO3 contents after heat-treatment were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The dependence of the volume stability and thermo-mechanical properties of castables on the micro-sized MgCO3 addition was discussed with respect to the in-situ spinel formation.