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 tem-
perature. 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.