Influence of Al2O3-SiO2ratio on viscosities of CaO-Al2O3-SiO2melt

Abstract

The influence of Al2O3/SiO2 ratio on viscosity of CaO-Al2O3-SiO2 melt was investigated by the rotating cylinder method in this study. Three groups of compositions with different CaO contents of 0.35, 0.4 and 0.45 were studied. From the experimental results, it was concluded that viscosity always first increases and then decreases as gradually increasing Al2O 3/SiO2 ratio. The appearance of viscosity maximum may be resulted from the opposite variation tendencies of mean bond strength and the degree of polymerization of melt with Al2O3/SiO 2 ratio. When substituting SiO2 by Al2O 3, the mean bond strength decreases because of the weak Al-O bond relative to Si-O bond, which decreases viscosity; while the degree of polymerization is enhanced by the charge compensation effect of Al3+ ion, which increases viscosity. Our new proposed viscosity model can well describe the viscosity variation of CaO-Al2O3-SiO 2 melt. © 2013 ISIJ.