Near zero thermal performance loss of Al-Si microcapsules with fibers network embedded Al2O3 /AlN shell

Al-Si alloy, a high temperature phase change material, has great potential in thermal management due to its advantages of high heat storage density and thermal conductivity. Microencapsulation of Al-Si alloy is one of the effective techniques to solve high temperature leakage and corrosion. In this paper, com-mercial Al-10Si alloy micro powders were encapsulated with flexible ceramic shells whose total thickness is below 1 mu m by hydrothermal treatment and heat treatment in N 2 atmosphere. The compositions and microstructures were characterized by XRD, SEM and TEM. The shell was composed of AlN fibers net-work structure embedded with alpha-Al2O3/AlN which prevented the alloy from leaking and oxidizing, as well as had excellent thermal stability. The latent heat of microcapsules was 351.8 J g -1 for absorption and 372.7 J g -1 for exothermic. The microcapsules showed near zero thermal performance loss with latent heat storage (LHS)/ release (LHR) was 353.2/ 403.7 J g -1 after 30 0 0 cycles. Compared with the published Al-Si alloy microcapsules, both high heat storage density and super thermal cycle stability were achieved, showing promising development prospects in high temperature thermal management. (c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

This paper presents the encapsulation of commercial Al-10Si alloy micro powders using hydrothermal treatment and heat treatment techniques. The flexible ceramic shells with excellent thermal stability were composed of AlN fibers network structure embedded with alpha-Al2O3/AlN. The microcapsules showed outstanding latent heat storage and release performance, as well as near zero thermal performance loss after 3000 cycles.