In this paper a novel SiO₂@NaNO₃ microcapsule thermal storage material is successfully fabricated via water‐limited sol‐gel method. The effects of SiO₂ nanoparticles on the microstructures, thermal conductivity, specific heat capacity, latent heat and thermal stability are investigated. SEM and TEM investigation indicates that the spherical SiO₂ nanoparticles with an average diameters of 30 nm are coated on the surface of NaNO₃ evenly to form a homogeneous and stable core‐shell structure. Microencapsulated composites are characterized by XRD and FTIR to determine the chemical compositions and structures. The thermal conductivity of SiO₂@NaNO₃ microcapsules is significantly enhanced by 62.9% (0.756 W m⁻¹ K⁻¹) compared with 0.464 W m⁻¹ K⁻¹ of that of NaNO₃. In addition, the latent heat, phase change temperature, specific heat capacity and thickness of shell of the microencapsulated NaNO₃ with 18.1 wt% SiO₂ were 310.1°C, 144.7 J g⁻¹, 1.831 J/(g·K), and 80‐150 nm, respectively. Furthermore, microencapsulated NaNO₃ have excellent shape and thermal stability at working temperature range. SiO₂ nanoparticles are uniformly attached to the modified NaNO₃ by electrostatic interaction to create a physical protective SiO₂ barrier, which can effectively inhibit the leakage and cauterization of melting NaNO₃.

中文翻译：

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SiO2 @ NaNO3微胶囊储热材料的微观结构和热性能研究

本文通过水限制溶胶-凝胶法成功地制备了一种新型的SiO ₂ @NaNO ₃微囊储热材料。研究了SiO ₂纳米颗粒对微结构，导热系数，比热容，潜热和热稳定性的影响。SEM和TEM研究表明，平均直径为30 nm的球形SiO ₂纳米颗粒均匀地涂覆在NaNO ₃的表面上，形成均匀且稳定的核-壳结构。通过XRD和FTIR对微囊复合材料进行表征，以确定其化学组成和结构。SiO ₂ @NaNO ₃的热导率与NaNO _3的0.464 W m ^-1 K ^-1相比，微胶囊显着提高了62.9％（0.756 W m ^-1 K ^-1）。另外，潜热，相变温度，比热容和厚度的微囊化纳米壳₃与18.1重量％的SiO ₂分别为310.1℃，144.7Ĵ克^-1，1.831焦耳/（克·K），和分别为80-150 nm。此外，微囊化的NaNO ₃在工作温度范围内具有优异的形状和热稳定性。SiO ₂纳米颗粒均匀地附着在改性的NaNO _3上通过静电相互作用产生物理保护性SiO ₂阻挡层，可以有效抑制熔融的NaNO ₃的泄漏和烧灼。