Physical, chemical and thermal characterization of alumina-magnesia-carbon refractories

Alumina-magnesia-carbon refractories (AMC) are of great technological interest for their use as linings for iron and steelmaking ladles. In this paper, the methodology implemented for the physical, chemical and thermal characterization of AMC refractories is presented along with the obtained results. These results are essential for the study of the chemical and mechanical behavior of these materials, which the present work frames. AMC bricks comprise different amounts of alumina, sintered or electrofused magnesia, graphite and antioxidant additives bonded together with a phenolic resin. The variety of components, be they oxidic, metallic or polymeric in nature, and the complexity of the final microstructure and texture make characterizing these refractories a difficult task. In the present work, several complementary techniques were used in combination: X-ray fluorescence, plasma emission spectroscopy, gravimetry, X-ray diffraction, differential thermal and thermogrametric analyses, reflection optical microscopy and scanning electron microscopy, density and porosity measurements, dilatometric analysis and permanent linear change measurements. The results of these different techniques were analyzed separately and together in order to obtain a detailed description of each refractory in relation to its physical and chemical characteristics and thermal evolution. In addition, the characterization was completed by evaluating the mechanical properties at room temperature, such as the mechanical strength and Young׳s modulus.