关键词: 熔盐, 纳米粒子, 熔融分散, 热物性, 微观结构

Abstract:

To observe the effect of nanoparticle on the thermal physical properties of the low melting point eutectic mixed nitrate salt. In this study 1% (mass) SiO₂ nanoparticles with the average size of 20 nm were doped into the mixed salt[Ca(NO₃)₂·4H₂O-KNO₃-NaNO₃-LiNO₃] to obtain molten-salt nanocomposites at different dispersion condition by the high temperature melting dispersion method. Specific heat capacity and thermal diffusivity of the nanocomposites were analyzed by differential scanning calorimeter (DSC) and laser flash apparatus (LFA). Then the thermal conductivity was gotten. The results show that at the stirring rate of 600 r/s the thermal physical properties of the molten-salt nanocomposites vary with the mixing time (15, 45, 90, 120 and 150 min). At the mixing time of 45 min, the thermal physical properties of the molten-salt nanocomposites reach the optimum enhancement. The average enhancement of the specific heat capacity, thermal diffusivity and thermal conductivity was 11.5%, 12.9%, and 26.4%, respectively. The scanning electron microscope (SEM) found that a large number of special nanostructures (resembling chain-like nanostructures) existed on the surface of solid molten-salt nanocomposites. The special nanostructures with large specific surface area and high surface energy may enhance the specific heat capacity and thermal conductivity of the molten salt nanocomposites.

Key words: molten salt, nanoparticle, molten-dispersion, thermal physical properties, nanostructure