Factors controlling the mechanical behavior of alumina–magnesia–carbon refractories in air

This work analyzes the mechanical behavior of alumina-magnesia-carbon (AMC) refractories in air up to 1260 °C. AMC refractory bricks are used on sidewalls and bottoms working linings of steel-making ladles. In plant, AMC bricks are exposed to air atmosphere during the periods of time when the ladle is empty, such as preheating. Stress–strain relationships were determined in compression, and the following parameters were calculated from these curves: strength, apparent Young's modulus, fracture strain and yield strength. Young's modulus at room temperature was also determined by the impulse excitation technique. To identify the main determining factors, the tested specimens were analyzed by apparent porosity measurements, X-ray diffraction and scanning electron microscopy coupled with X-ray dispersive energy. Thermodynamic simulations of the AMC refractories were also performed using FactSage software, so as to understand the mineralogical changes that occur in the refractories as temperature increases.