Influence of Al₂O₃/SiO₂ Ratio on Viscosities of CaO–Al₂O₃–SiO₂ Melt

摘要

The influence of Al_(2)O_(3)/SiO_(2) ratio on viscosity of CaO–Al_(2)O_(3)–SiO_(2) 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 Al_(2)O_(3)/SiO_(2) 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 Al_(2)O_(3)/SiO_(2) ratio. When substituting SiO_(2) by Al_(2)O_(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 Al~(3+) ion, which increases viscosity. Our new proposed viscosity model can well describe the viscosity variation of CaO–Al_(2)O_(3)–SiO_(2) melt.