Interconnected Al/Al2O3 Porous Scaffolds Fabricated by In Situ Oxidation for Phase Change Energy Storage

Abstract

Conventional porous ceramic supports for phase change materials (PCMs) suffer from low thermal conductivity, high sintering temperatures, and complex fabrication processes. To address these limitations, this study developed an integrated manufacturing strategy combining foam-gelcasting with vacuum freeze-drying. Using Al powder as the precursor, an Al/Al₂O₃ scaffold was constructed via a controlled partial oxidation process in air at low sintering temperature. This innovative design strategically utilizes the in situ formed Al₂O₃ framework to ensure mechanical strength and structural stability, while the intentionally retained metallic Al network guarantees high thermal conductivity. The resulting scaffold, sintered at 750°C, achieves a high open porosity of 91.60% and a compressive strength of 0.48 MPa, enabling a high paraffin loading capacity of 83.27%. The final composite PCM exhibits a comprehensive set of outstanding properties, including a thermal conductivity of 0.434 W/(m·K), a solar absorptance of 85.8%, and excellent thermal cycling stability (mass loss < 6% after 50 cycles). This work establishes a novel and efficient route for fabricating high-performance composite PCMs that are tailored for integrated solar thermal energy harvesting and storage.