In response to the escalating energy crisis and the mounting pressure associated with industrial solid waste disposal

the development of efficient and stable composite phase change heat storage materials is of paramount significance. This study uses solar salt as the phase change medium

with steel slag and fly ash employed as porous skeleton materials. A novel composite phase change heat storage material is synthesized via the cold pressing and hot sintering process. Through systematic optimization of material composition

the optimal mass ratio is determined as fly ash: steel slag: solar salt equal to 25:25:50. The characterization results demonstrate excellent chemical compatibility among the composite components

with no formation of new phases. The composite exhibits superior thermal energy storage performance

with a phase change latent heat of 57.96 J/g

a heat storage density of 291.968 J/g within the temperature range of 100～400 ℃ and a thermal conductivity of 0.952 W/(m·K). Mechanical property testing reveals a high compressive strength of 55.0 MPa. Crucially

the material maintains stable phase change behavior and structural integrity after 3 600 thermal cycles

with a mass loss rate below 0.05%. This research not only facilitates the high-value-added utilization of industrial solid wastes but also provides novel insights into the material design for medium and high-temperature thermal energy storage systems.