Thermal Evolution of Al2O3-MgO-C Refractories

In spite of the high cost of bauxite, Al2O3-MgO-C refractory bricks (AMC) are widely used for steelmaking vessel working linings due to their excellent properties: high temperature mechanical strength and high resistances to both thermal spalling and slag corrosion. In part, these properties stem from the thermal evolution of the phases and the microstructure of AMC refractories, such as the transformation of the aluminum metal (usually added as antioxidant) in Al4C3 and the formation of spinel (MgAl2O4). In this work, the thermal evolution of the phases of three different AMC commercial bricks used in sidewalls and bottom of steelmaking ladles between 400 and 1400 ¡C in air was studied. The variation of the mineralogical composition was analyzed using X-ray diffraction and the differences found between the materials were related to their compositional and microstructural differences. With this aim, an exhaustive characterization of the as-received refractory materials by several analytical techniques was also carried out.