Mechanical Microencapsulation and Shell Formation Mechanism of High Working Temperature Al-25Si Alloy Phase Change Material

Phase change materials (PCMs) based high temperature latent heat storage (LHS) technology has shown great potential for thermal energy storage utilization and thermal management of chemical engineering processes. Particularly, metal based PCMs, and their alloys, are appealing because of their high thermal conductivity and high heat storage density by volume compared with inorganic salts. Nonetheless, leakage and eventual corrosion of containers are major drawbacks for practical uses. While conventional microencapsulation methods of PCMs face the challenges of shell strength and corrosion resistance inability, appropriate microencapsulation strategies can overcome these limitations. Herein, this research introduces a new approach for microencapsulation of high working temperature Al-25Si alloy PCMs. Here, the high-speed impact blending (HIB) technique based mechanical encapsulation method was utilized to develop an Al-25Si@α-Al2O3 microencapsulated PCM (MEPCM). The fabrication strategy includes 3 steps of mixing, HIB mechanical encapsulation, and heat oxidation treatment. The MEPCM exhibits a complete core (Al-25Si) - shell (α-Al2O3) structure, high energy storage density of over 200 J/g, and remarkable thermal stability up to 1000 heat storage-release cycles without leakage. The mechanical encapsulation method not only facilitates mass production of MEPCMs but also gives room for selection of diverse core/shell materials, paving the way for the development of multifunctional materials for a broad range of applications.