The Effect of Chelate Compounds on the Hydration Process of MgO–Al₂O₃ Phase System under Hydrothermal Conditions

Abstract

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.

Keywords

• castables
• hydration
• hydraulic binders
• heat treatment
• refractory