Jiang Zhoufeng, Zhao Fengqi, Qin Zhao, Xu Yi, Wang Ying, Jiang Yi-Fan, An Ting, Qu Wengang, Zhang Ming, Liu Hexin, Zhang Bingbing, Xiong Lianghua
National Key Laboratory of Energetic Materials, Xi'an Modern Chemistry Research Institute, Xi'an 710065, People's Republic of China.
Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, People's Republic of China.
ACS Appl Mater Interfaces. 2024 Aug 28;16(34):45640-45659. doi: 10.1021/acsami.4c07029. Epub 2024 Aug 16.
AlH has gained considerable attention as a fuel additive due to its ability to offer high specific impulse and superior combustion performance. However, few studies have focused on the fragmentation and agglomeration behavior of AlH. This study investigated the effects of fragmentation of AlH and AlH/PVDF particles on the thermal decomposition, ignition, agglomeration, and combustion of HTPB propellants. Thermal analysis indicated that AlH and AlH/PVDF can accelerate the decomposition of ammonium perchlorate by abundant active sites for the adsorption of the decomposition intermediates. Single-particle combustion uncovered the mechanism behind the directional spray of molten Al from the AlH particle and the fragmentation of the AlH/PVDF particle. The melting of porous Al induces particle shrinkage due to solid-liquid interfacial tension and the structural restoration of the oxide shell, which consequently results in the sealing of cracks in the oxide shell of AlH. Additionally, the accumulation of internal tensile stress leads to the reopening of these cracks and the directional ejection of the molten Al. The flexible oxide shell contributes to a smaller minimum normalized diameter of the AlH/PVDF particle, aiding in the generation of internal tensile stress, while the sublimation of AlF induced the fragmentation. Synchrotron-based X-ray imaging revealed the formation of aggregates promoted by molten Al, the splitting of AlH aggregates due to hydrogen explosion, and the enhanced fragmentation of AlH/PVDF due to the synergistic effect of hydrogen explosion and the sublimation of AlF. Compared to raw particles, the CCPs (condensed combustion products) of SP2 propellant display a 48% reduction in average size ( = 24.5 μm), whereas there is an over 89% decrease in particle size for the CCPs of SP3 propellant ( = 5.14 μm). This study contributes to understanding the fragmentation of AlH and AlH/PVDF upon ignition and combustion, providing valuable insights for the development and optimization of propellants containing AlH.
由于具有提供高比冲和卓越燃烧性能的能力，氢化铝（AlH）作为一种燃料添加剂受到了广泛关注。然而，很少有研究关注AlH的破碎和团聚行为。本研究调查了AlH和AlH/聚偏氟乙烯（PVDF）颗粒的破碎对端羟基聚丁二烯（HTPB）推进剂热分解、点火、团聚和燃烧的影响。热分析表明，AlH和AlH/PVDF可以通过大量用于吸附分解中间体的活性位点加速高氯酸铵的分解。单颗粒燃烧揭示了AlH颗粒中熔融铝定向喷射以及AlH/PVDF颗粒破碎背后的机制。多孔铝的熔化由于固液界面张力和氧化壳的结构恢复而导致颗粒收缩，从而导致AlH氧化壳中的裂纹密封。此外，内部拉应力的积累导致这些裂纹重新打开以及熔融铝的定向喷射。柔性氧化壳有助于减小AlH/PVDF颗粒的最小归一化直径，有助于产生内部拉应力，而AlF的升华则导致破碎。基于同步加速器的X射线成像揭示了由熔融铝促进的团聚体形成、由于氢气爆炸导致的AlH团聚体分裂以及由于氢气爆炸和AlF升华的协同作用导致的AlH/PVDF破碎增强。与原始颗粒相比，SP2推进剂的凝聚燃烧产物（CCPs）平均尺寸降低了48%（ = 24.5μm），而SP3推进剂的CCPs颗粒尺寸减小了超过89%（ = 5.14μm）。本研究有助于理解点火和燃烧时AlH和AlH/PVDF的破碎情况，为含AlH推进剂的开发和优化提供了有价值的见解。
