| Abstract: | The development of high temperature phase change materials(PCMs)with great comprehensive per-formance is significant in the future thermal energy storage system.In this study,novel and durable Al-Si/Al2O3-AlN composite PCMs with controllable melting temperature were successfully synthesized by using pristine Al powder as raw material and tetraethyl orthosilicate as SiO2 source.The Al2O3 shell and Al-Si alloy were in-situ produced via the substitution reaction between molten Al and SiO2.Impor-tantly,the crack caused by the incomplete encapsulation of the Al2O3 shell could repair itself by the nitridation reaction of internal molten Al and thereby forming a highly dense Al2O3-AlN composite shell.The produced dense Al2O3-AlN composite shell could significantly improve the thermal cycling stability of composite PCMs,and thus,the thermal storage density decrease of the Al-Si/Al2O3-AlN(59.8 J/g to 77.7 J/g)was far less than that of the Al-Si/Al2O3(118.5 J/g)after 3000 thermal cycles.Moreover,the syn-thesized Al-Si/Al2O3-AlN still exhibited a controllable melting temperature(571.5-637.9℃),relatively high thermal storage density(105.6-150.7 J/g),great dimensional stability and structural stability after 3000 thermal cycles.Hence,the synthesized Al-Si/Al2O3-AlN composite PCMs,as promising preferential thermal energy storage materials,can be stably used in the energy utilization efficiency improvement of various systems for more than 6 years. |
