Abstract

Introduction Torpedo ladles are typically lined with alumina silicon carbide carbon refractories .These materials withstand a broad range of temperature and undergo severe thermal cycles during the campaign. As all bricks are assembled in a restricted condition that retains the natural thermal expansion of the refractory, spalling effect may occur. Many efforts have been made on the development of torpedo ladle bricks. As it is difficult to analyze the thermomechanical behavior of constrained bricks under typical laboratory conditions, analysis by the finite element method (FEA) can be used as an important tool to predict the behavior of the material. The main challenge of FEA simulations applied to refractories is the selection of the correct failure criteria for it. Stress-strain curves and FEA simulations, Hirota et al. (1995) have proposed a spalling mechanism for torpedo ladle bricks during operation. On the basis of this brief review, the purpose of the present work was (i) to evaluate the effect of some variables on the thermomechanical behavior of Al2O3-SiC-C refractories by means of FEA simulations and thus (ii) establishing their relative importance for the development of a torpedo ladle brick with enhanced spalling resistance. Material and Properties One typical Al2O3-SiC-C refractory was evaluated. After curing at 200°C, 6h, the samples were characterized by thermal expansion. Heat treated samples were characterized by stress-strain curves at different temperatures under compression. The thermal conductivity was obtained by standard values provided by Magnesita Refractories. The FEA simulation was run using Ansys® Mechanical 14.0. In order to validate the data, the first step was to simulate the spalling mechanism as proposed by Hirota et al. (1995).  Afterwards, different values of thermal expansion, stress and strain and thermal conductivity were inputted in the software to assess the key properties of the material in an attempt to enhance the spalling resistance. Results and Conclusion  The simulations by FEA indicated that the failure criteria selected in this work are in accordance with the spalling mechanism proposed in the literature and with practical observations. As the stress values were systematically higher after the breakage of the bricks’ edges, it seems more reasonable to avoid spalling by hindering the formation of broken edges than by avoiding the phenomenon itself. The effect of key aspects on the thermomechanical behavior of Al2O3-SiC-C brick was simulated by FEA. It is proposed that the key variables to be controlled are the following: stress, thermal expansion, strain and thermal conductivity. The highest and lowest effects on the normal stresses and shear stress were observed when the inputted stress value was varied by ±20%. The findings of the present investigation may be useful for developing refractories with longer service life.