Pore evolution and its effect on slag resistance of Al₂O₃–SiC–C castables

Al2O3–SiC–C castables with different particle size distributions (PSD) corresponding to different Andreassen distribution modulus (q) values, were fabricated, and their apparent porosity, permeability, pore size distribution and mean pore size, examined, after heat-treatment at different temperatures. The apparent porosity of Al2O3–SiC–C castable samples dried at 110°C for 24 h or fired at 1450°C for 3 h, decreases with increasing the q value from 0.21 to 0.23, but starts to increase on further increasing the q value to >0.23, i.e., it reaches the minimal value when q = 0.23.The change of permeabiliy with q is similar, although it reaches the minimal value when q = 0.22. The mean pore sizes of Al2O3–SiC–C castable samples dried at 110°C for 24 h increase with increasing q from 0.21 to 0.25, whereas for samples fired at 1450°C for 3 h, they have no obvious regularity. Pore size distributions of Al2O3–SiC–C castable samples after treated at different temperatures, are evidently scattered when q = 0.21, 0.22 and 0.25, but tend to become continuous when q = 0.23 and 0.24, in particular when q = 0.23. The Al2O3–SiC–C castable with q = 0.23 shows the best slag resistance because of its relatively narrow pore size distribution. In addition, our results reveal that PSD has little, whereas temperature has more obvious, effect on apparent porosity, permeability, mean pores size and pore size distribution of Al2O3–SiC–C castables.