High-value utilization of high-silicon magnesite: Mg-Si-Al reconfiguration to enhance corrosion resistance of carbon containing alumina refractories and its mechanism

To address the diminished corrosion resistance of low carbon Al 2 O 3 –C refractories resulting from reduced carbon content, this study incorporated MgSiN 2 prepared by reconstructing high-silicon magnesite mineral phases into Al 2 O 3 –C refractories, and prepared samples at 1450 °C in an N 2 atmosphere. The influence of MgSiN 2 addition level on the phase composition, microstructure, mechanical properties, and corrosion resistance of the material was comprehensively explored. The findings demonstrated that MgSiN 2 in-situ generated flake Mg-Sialon and granular MgAl 2 O 4 ceramic phases, forming a three-dimensional interwoven folded network structure within the matrix, significantly boosting the aggregate-matrix interfacial bonding. When the content of MgSiN 2 was 3 wt%, the porosity of the material was the lowest, and the cold modulus of rupture and cold crushing strength were the best due to the synergistic effect of the generated ceramic phases. With the increase of MgSiN 2 content, the corrosion index decreased from 79.4% to 59.1%, and the corrosion resistance of the material gradually improved.