Novel high thermal conductivity alumina/salt composites for thermal energy storage: Effect of wettability on microstructure and properties

In this work, alumina foam ceramics (AFC) were prepared by foaming method, and AFC/salt composite phase change materials were prepared by melt infiltration method using AFC as skeleton materials. The results showed that AFC had good chemical compatibility with Na2SO4 and NaCl. The salt contents of AFC/Na2SO4 and AFC/NaCl were 37.8 wt% and 31.7 wt%, respectively, with compressive strength of 100.1 MPa and 72.8 MPa, thermal conductivity of 5.53 W/m·K and 6.40 W/m·K, and energy density of 1129 J/g and 1019 J/g, respectively. Due to the better wettability, AFC and Na2SO4 form a chimeric structure, which has better binding and bonding strength, and is not prone to molten salt leakage. AFC/ Na2SO4 is expected to be applied to industrial waste heat recovery and solar thermal power generation with periodic temperature changes.