Thermal Conductivity Measurements of Some Synthetic Al2O3-CaO-SiO2 Slags by Means of a Front-Heating and Front-Detection Laser-Flash Method

Abstract

The thermal conductivities of some synthetic slags containing Al2O3, CaO, and SiO2 have been determined in the temperature range between 1623 K (1350 °C) and 1823 K (1550 °C) by applying a front-heating front-detection laser-flash method. In this method, the temperature response curve is measured in the short initial time period immediately after irradiating a laser pulse. The resultant values obtained by this method are unaffected by the radiative heat transfer. The temperature dependence of the thermal conductivity values were found not to be significant for all slag samples currently investigated. The thermal conductivity (λ) of samples is represented with standard deviation less than 2 pct of its value as a function of compositions as follows: $$ \lambda = - 0.48\left[ {{\text{Al}}_{ 2} {\text{O}}_{ 3} } \right] - 0.57\left[ {\text{CaO}} \right] - 0.55\left[ {{\text{SiO}}_{2} } \right] + 57.1{\text{ W m}}^{ - 1} {\text{ K}}^{ - 1} $$ where [Al2O3], [CaO], and [SiO2] are molar percent of Al2O3, CaO and SiO2, respectively. The equation is suggested to cover the region of the following compositions: 8.0 mol pct < Al2O3 <21.0 mol pct, 31.5 mol pct < CaO <41.5 mol pct and 43.0 mol pct < SiO2 <58.1 mol pct. The addition of Al2O3 to slags with a constant CaO/SiO2 molar ratio resulted in an increase in thermal conductivity. In contrast, the effects of addition of SiO2 and CaO are found to be insignificant.