Thermal conductivity of alumina-carbon composite brick and its related phase analysis in a dissected blast furnace

Abstract

Excellent performance of refractories in blast furnace hearth is one of the important factors to ensure longevity of blast furnaces. As an emerging refractory for application in blast furnace, alumina-carbon composite brick combines the superior properties of carbon and alumina. Firstly, the thermal conductivity of alumina-carbon composite brick was measured by the laser flash method and the new device method to verify the feasibility of the new device method for thermal conductivity measurement. Secondly, the influence of heating temperature of the heating furnace and cooling water flow on the thermal conductivity of the alumina-carbon composite brick, and the comparison of the thermal conductivity of carbon brick, alumina-carbon composite brick and corundum brick were investigated to confirm the heat transfer mechanism of alumina-carbon composite brick. High thermal conductivity and erosion resistance to slag and hot metal of the alumina-carbon composite brick are consequent from: (a) reasonable composition combination of Al2O3, C, SiO2, SiC, etc., (b) dense structure, small pore diameter, and uniform distribution of the pores, (c) the generated SiC whiskers and Al6Si2O13, which can fill in the pores and reduce the porosity. Finally, the analysis on the phase distribution of the alumina-carbon composite brick in a dissected blast furnace was performed to illustrate the relationship between the erosion resistance and the thermal conductivity of alumina-carbon composite brick.