Abstract Aluminum (Al)-based thermite, due to its high energy density and low cost, has found wide applications in aerospace propulsion, explosion, pyrotechnics, thermal batteries, and power generations. Though significant efforts have been devoted to improving the ignition and combustion performance of Al-based thermites by using nano-Al, micron-Al (m-Al) remains of practical importance over nano-Al due to its lower cost and smaller dead mass. For m-Al based thermite, the main approach to improve its ignition and combustion performance is to bring Al and metal oxide as close as possible to facilitate the oxidizer diffusion process. Herein, we demonstrated two simple synthesis methods, i.e., the precipitation (PC) method and displacement (DP) method, to prepare m-Al/CuO thermites with the intention to bring Al and CuO to shorter diffusion distance and achieve better dispersion. The PC-thermites have flocculent nanostructured CuO closely attached to the surface of m-Al, and the DP-thermites have a dense shell of CuO coated on the surface of m-Al. Both PC- and DP-thermites have reduced agglomeration and diffusion distance over the traditional mechanically mixed (MM)-thermites that have randomly distributed and agglomerated CuO and m-Al. Consequently, both PC- and DP-thermites exhibit shorter ignition delay time, lower reaction onset temperatures, higher heat release, larger pressure rise, and extended reactivity limits than MM-thermites. Particularly, PC-thermites, due to their flocculent structures, exhibit the shortest ignition delay time, lowest reaction onset temperature, and highest amount of heat release. Moreover, the superior ignition and combustion performance of PC- and DP-thermites is more pronounced under high heating rates over low heating rates. Similar PC and DP methods are applicable to prepare diverse thermites with reduced diffusion distance and improved dispersion to improve their ignition and combustion properties.

中文翻译：

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通过不同的合成方法调整微米-Al/CuO铝热剂的形态、点火和燃烧特性

摘要 铝（Al）基铝热剂由于其能量密度高、成本低，在航空航天推进、爆炸、烟火、热电池和发电等方面有着广泛的应用。尽管通过使用纳米铝来提高铝基铝热剂的点火和燃烧性能已经付出了巨大的努力，但微米铝（m-Al）由于其较低的成本和较小的死质量，仍然比纳米铝具有实际重要性。对于m-Al基铝热剂，提高其点火和燃烧性能的主要方法是使Al和金属氧化物尽可能接近，以促进氧化剂扩散过程。在这里，我们展示了两种简单的合成方法，即沉淀（PC）法和置换（DP）法，制备 m-Al/CuO 铝热剂，旨在使 Al 和 CuO 的扩散距离更短并实现更好的分散。PC-铝热剂具有紧密附着在间铝表面的絮状纳米结构CuO，而DP-铝热剂在间铝表面涂覆有致密的CuO壳。与具有随机分布和团聚的 CuO 和 m-Al 的传统机械混合 (MM) 铝热剂相比，PC 和 DP 铝热剂都减少了团聚和扩散距离。因此，与 MM 铝热剂相比，PC 和 DP 铝热剂都表现出更短的点火延迟时间、更低的反应开始温度、更高的放热、更大的压力上升和更长的反应性限制。特别是 PC-铝热剂，由于其絮状结构，表现出最短的点火延迟时间，最低的反应起始温度，和最高的热量释放。此外，PC 和 DP 铝热剂的卓越点火和燃烧性能在高加热速率下比低加热速率更显着。类似的 PC 和 DP 方法适用于制备各种具有减小扩散距离和改进分散性的铝热剂，以改善其点火和燃烧性能。