Composite phase change material based on Al alloy with durability of over 10,000 cycles for high-temperature heat utilization

High-temperature latent heat storage (LHS) technology using alloy-based phase change materials (PCMs) is promising for high-temperature heat applications owing to its high heat storage capacity at a constant temperature. Microencapsulated PCMs (MEPCMs) coated with stable ceramics can help prevent corrosive reactions observed in alloy PCMs during heat storage. Because MEPCMs are considered as ceramic particles, a composite PCM can be prepared by compositing them with a sintering aid. In this study, composite PCMs consisting of MEPCM with Al–12 mass Si alloy (melting point: 577 °C) particles with diameters of 31.7 or 68.2 μm, and α-Al2O3 as the sintering aid were prepared. The MEPCM used in the preparation of the composite PCM included alumina hydroxide and various alumina polymorphs as coatings. Pellet-like compacts were successfully produced by mixing each MEPCM with α-Al2O3. After heat treatment, the composite PCMs retained their shape. In particular, the latent heat capacities of the composite PCMs made from small and large MEPCMs with α-Al2O3 coatings were 171 and 231 J g−1, respectively. Moreover, the composite PCMs retained their shape and more than 80 of their latent heat capacity after 10,000 and 1000 cycles. The developed composite PCMs, with their high latent heat capacity and durability, can be employed for high-temperature heat applications. © 2023 Elsevier Ltd