Relationship between thermal conductivities and viscosities of CaOSiO₂- Al₂O₃-R₂O (R=Na, K, Li) melts

The thermal conductivities of silicate melts play an important role in the solidification and refining of metals; these conductivities depend on the SiO₄ network structure, and are reduced by the addition of Na₂O or K₂O. In addition, the viscosity of the silicate system is related to the network structure of SiO₂ and Al₂O₃, and changes with the addition of R₂O (R=Na, K, Li). In this study, the thermal conductivities of CaO-SiO₂-Al₂O₃-R₂O molten slags were measured using a front-heating front-detection laser flash method, which performed the measurements within 4-12ms after laser irradiation and without the effects of thermal radiation and convection. The correlation between the viscosity measured by Sukenaga et al. and the thermal conductivity obtained in the present study was discussed. Although the thermal conductivity exhibited almost no dependence on temperature, the viscosity decreased rapidly with increasing temperature. Furthermore, depending on the structure of the melts, the addition of R₂O had both positive and negative effects on viscosity. However, the thermal conductivity was, reduced by the addition of R₂O.