Tailoring the Microstructure of Cement‐Bonded Alumina–Magnesia Refractory Castables

Abstract

Nature has various hierarchical structural materials, which show a high work of fracture despite the brittle characteristics of most of their constituents. This aspect is mainly a consequence of the appropriate alignment of mineral platelets and organic protein layers. As organic materials do not attain the high‐temperature working conditions of the refractory castables, an alternative should be considered in order to provide suitable thermo‐mechanical behavior (high creep and thermal shock resistance). Taking into account the usual microstructure of cement‐bonded alumina–magnesia refractory castables, comprising low‐temperature melting point phases in the CaO–MgO–Al2O3‐–SiO2 system and calcium hexaluminate (CA6) platelets, this material could be a good candidate to be designed based on the structure of biological materials, but fit to the high‐temperature working conditions. Therefore, this work addresses the evaluation of different liquid sources (transient or not) in order to master the CA6 grain morphology, their location, and stability in the castable's microstructure. As a consequence, outstanding creep resistance was attained, pointing out suitable alternatives to design technological bioinspired refractory castables.