To reduce the production costs and carbon emissions associated with phase change composite materials

coal gangue was utilized as the skeletal raw material

and NaNO3 was used as the phase change material to prepare of composite thermal energy storage materials. Through the cold pressing and hot sintering method

nine distinct composite phase change materials with varying coal gangue to NaNO3 ratios were successfully synthesized. The fundamental properties of these coal gangue-based composite phase change materials were systematically investigated

encompassing thermal storage capacity

microstructural characteristics

mechanical strength

chemical compatibility

and economic viability. Results demonstrated that the composite with a coal gangue to NaNO3 mass ratio of 4.5:5.5(designated as sample SC3) exhibited optimal performance across all evaluated parameters. Specifically

sample SC3 achieved a mechanical strength of 49.33 MPa. Within the temperature range of 100 ℃ to 335 ℃

its thermal storage capacity reached 399.29 J/g

accompanied by a thermal conductivity of 1.484 W/(m·K). Elemental distribution within this composite was found to be homogeneous

and chemical compatibility between constituents was excellent. Furthermore

after undergoing 1858 thermal cycles of heating and cooling

sample SC3 retained remarkable thermal storage performance

stable mechanical properties

and maintained its physical integrity without degradation.