Abstract Metastable intermolecular composites (MICs) exhibit applications in supplying thermal energy to miniature systems, although they are commonly fabricated as powders, films, multi-layers and other heterostructures which desire an effective interface between reactive components but are not colloids and typically immobile. Little information is available in the literature on fabrication and characterization of standing-alone and mobile core-shell MIC micro-particles. In this paper, we report on a wet-chemistry method to synthesize micron-sized spherical colloids of Al/CuO with a core-shell structure. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) were employed to characterize the micro-structure and element distribution at the Al/CuO interface, while differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to examine the thermochemical properties of these MIC spherical particles. It was found that for these core-shell micron-sized particles, the onset temperature (about 580⁰C) corresponding to the exothermic reaction is similar to that of the powder mixtures composed of Al and CuO nanoparticles (around 548⁰C), while the activation energy of the former (328 kJ/mol) is much lower than that of the latter (438 kJ/mol). Direct contact and subsequent solid-state diffusion of reactive components at the interface of the Al/CuO core-shell are attributed to these experimental observations. The specific energy release (807 J/g) is however significantly smaller than that of the nano-powder mixtures (1107 J/g) due to the limited thickness of the CuO shell which is originated from the restrictions of the wet chemistry method. Future work includes testing the energetic performance of these core-shell colloids in a liquid or solution ambient.

中文翻译：

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球形胶体制备的Al/CuO核壳复合微粒的能量特性

摘要 亚稳态分子间复合材料 (MICs) 在为微型系统提供热能方面表现出应用，尽管它们通常被制造为粉末、薄膜、多层和其他异质结构，这些异质结构需要反应组分之间的有效界面，但不是胶体并且通常是不动的。文献中关于独立和移动核壳 MIC 微粒的制造和表征的信息很少。在本文中，我们报告了一种湿化学方法来合成具有核壳结构的微米级 Al/CuO 球形胶体。采用扫描电子显微镜 (SEM)、透射电子显微镜 (TEM) 和能量色散 X 射线光谱 (EDS) 来表征 Al/CuO 界面的微观结构和元素分布，而差示扫描量热法 (DSC) 和热重分析 (TGA) 用于检查这些 MIC 球形颗粒的热化学性质。研究发现，对于这些核壳微米级颗粒，其放热反应的起始温度（约 580⁰C）与由 Al 和 CuO 纳米颗粒组成的粉末混合物（约 548⁰C）相似，而活化能为前者（328 kJ/mol）远低于后者（438 kJ/mol）。反应组分在 Al/CuO 核壳界面处的直接接触和随后的固态扩散归因于这些实验观察。然而，由于湿化学方法的限制，CuO 壳的厚度有限，因此比能量释放 (807 J/g) 显着小于纳米粉末混合物 (1107 J/g)。未来的工作包括测试这些核壳胶体在液体或溶液环境中的能量性能。