Abstract:The eutectic point compositions of LiF-CaF2 and LiF-YbF3 molten salt systems were analyzed and determined by the extrapolated tangent method based on thermal analysis data, and the thermal conductivity and thermal expansion coefficient of the systems were experimentally measured with temperature and compared with the calculated results of the prediction model. The results show that LiF-22%CaF2 and LiF-21%YbF3 (mole fraction) as the proportion of the system are closer to the eutectic composition point. The thermal conductivity of the two eutectic systems drops with increase of temperature in the range of 950—1 200 K. The model estimation results are linear and the experimental values are nonlinear, and the model estimates are in good agreement with the experimental values in the liquid state; meanwhile, the thermal expansion coefficients of the systems rise with increase of temperature in the solid state below the melting point and begin to drop after reaching the melting point. In the completely melted the coefficient of thermal expansion of liquid molten salt is approximately linearly decreasing.