Study on the Synergistic Enhancement of Mechanical Properties of Magnesia-Chrome Refractory Bricks Through Component...

To meet the stringent industrial service requirements of magnesia-chrome refractory bricks, this study adopts a technical approach that synergistically combines precise component ratio optimization with a vacuum-pressure MgSO₄ salt impregnation process to investigate the performance optimization of magnesia-chrome bricks. Samples were prepared by controlled formulation mixing, pressing at 250 MPa, drying at 110 °C, and firing at 1750 °C. Phase composition, microstructure, and physical-mechanical properties were characterized by XRD, SEM, and standard refractory test methods. The optimal additions of chromite powder and Cr₂O₃ micro-powder were determined to be 3 wt.% and 2 wt.%, respectively, which reacted with periclase to form a secondary composite spinel, creating a dense spinel bridge network that connected adjacent grains. Furthermore, when the proportion of sintered magnesia powder (MgO > 97 wt.%) was increased to 11 wt.%, the material achieved efficient densification facilitated by enhancing sintering performance. Based on this optimized formulation, and due to the high elemental compatibility between MgSO₄ and the magnesia-chrome brick matrix as well as the excellent permeability of the solution, the MgSO₄ vacuum-pressure salt impregnation process was subsequently applied. The salt solution filled the open pores and microcracks of the material, forming a crystalline salt micro-pillar reinforcing phase. Consequently, the apparent porosity of the material decreased to 10.98%, the bulk density increased to 3.23 g/cm³, and the cold compressive strength and cold modulus of rupture reached as high as 113.52 MPa and 24.91 MPa, respectively. This study innovatively establishes a new pathway for enhancing the mechanical properties of magnesia-chrome refractory bricks through the synergistic design of component ratio optimization and salt impregnation process. The prepared magnesia-chrome refractory bricks exhibit both excellent mechanical properties and volume stability.