In refractory castables during heat treatment, there is a dynamic change from a hydraulic bond to a ceramic bond. During heating, the emission of water takes place; this changes the conditions inside the material to something similar to the hydrothermal ones. This influences the processes that occur during the heating of the castables, and in consequence, the properties of the final material. The aim of the work was to evaluate the influence of the chelate compounds like citric and tartaric acids, often used in castables as dispersing agents, on the properties of the MgO–Al2O3 phase system during hydrothermal treatment. The performed tests included an XRD analysis, a thermal analysis (TG–DSC–EGA), infrared spectroscopy (FTIR), and an SEM–EDS analysis. Based on the obtained results, it was found that even small amounts of chelate compounds have a strong impact on the processes under hydrothermal conditions which results in changes in the phase composition of the materials.

This study investigated the effect of the CaO/SiO2 mass ratio of steel slag on the corrosion behavior of spinel-forming alumina-based castables with a content of MgO (3–7 wt.%). Equiweight mixtures of castables and slags were calculated by FactSage, observed by HMTA, fired at 1350 °C, and investigated by XRD. From these results, we conclude that the presence of SiO2-rich phases accelerates the growth of the liquid phase in a narrow temperature range for the tested samples, which accelerates the degradation of castables. The static corrosion test was conducted by means of the coating method at 1450 °C. The corrosion index (IC) in the regions of castables affected by slags was calculated. Phases and phase distributions were evaluated by SEM-EDS. From these results, we conclude that for the slag with the lowest mass ratio of CaO/SiO2 (1.1), the reaction zone occurs only below the slag-refractory interface, which indicates the aggressive character of this slag.