Melt-Dispersion Mechanism for Energetic Reactions of Aluminum Nanoparticles

铝纳米粒子高能反应的熔融分散机制

• 批准号: 0755236
• 负责人: Valery Levitas
• 金额: --
• 依托单位: Texas Tech University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0755236&HistoricalAwards=false
• 关键词: Melt; Dispersion; Mechanism; Energetic; Reactions

CBET-0755236LevitasAluminum particles are becoming integrated into energetic formulations and considered for overlapping technologies such as materials synthesis and thermites for ordnance applications. Recently, a new mechanochemical mechanism has been introduced that shows potential for understanding extremely fast Al nanoparticle reactions. This theory applies during fast heating of Al nanoparticles, where the volume change due to melting of the Al core encased in an alumina shell induces extreme pressures of 1-2 GPa, resulting in a spallation of the oxide shell. The unbalanced pressure between the Al core and exposed surface creates an unloading wave with high tensile pressures, resulting in dispersion of small liquid Al clusters that fly at high velocity. Thus, nanoparticle reactions are not limited by diffusion. The proposed melt-dispersion mechanism is the only existing explanation that resolves a number of basic puzzles in nano-Al combustion. The goal of this project is to define the main conditions and controlling physical parameters for operation of the melt-dispersion mechanism for reactions of Al nanoparticles; to extend this mechanism for micron-scale particles; and to utilize obtained fundamental knowledge for the improvement of Al-based formulations. The following tasks will be considered: (a) develop comprehensive theories for physical processes participating in the melt-dispersion mechanism, (b) synthesize Al particles based on theoretical predictions and new particle design concepts, (c) study implications of the melt-dispersion mechanism experimentally, (d) expand the melt-dispersion mechanism to micron-scale particles, and (e) predict and experimentally confirm methods that will improve the reactivity of Al particles in various formulations. Beyond the potential for technological impact, a mentoring program will be developed where undergrads work with grad students in a research environment. In addition, nanoparticle combustion will be integrated into the combustion curriculum and a continuing-education program in energetic materials. The investigators also plan to organize special symposia devoted to "mechanochemical" processes at various international conferences.

CBET-0755236Levitas铝颗粒正在融入高能配方中，并考虑用于重叠技术，例如用于军械应用的材料合成和铝热剂。最近，一种新的机械化学机制被引入，它显示出理解极快的铝纳米颗粒反应的潜力。该理论适用于 Al 纳米粒子的快速加热过程，其中由于包裹在氧化铝壳中的 Al 核熔化而产生体积变化，从而产生 1-2 GPa 的极端压力，导致氧化物壳剥落。铝芯和暴露表面之间的不平衡压力产生具有高拉伸压力的卸载波，导致高速飞行的小液态铝团簇的分散。因此，纳米粒子反应不受扩散的限制。所提出的熔体分散机制是解决纳米铝燃烧中许多基本难题的唯一现有解释。该项目的目标是确定Al纳米颗粒反应熔融分散机制运行的主要条件和控制物理参数；将这种机制扩展到微米级颗粒；并利用所获得的基础知识来改进铝基配方。将考虑以下任务：（a）开发参与熔体分散机制的物理过程的综合理论，（b）根据理论预测和新的颗粒设计概念合成铝颗粒，（c）研究熔体分散的影响实验机制，（d）将熔体分散机制扩展到微米级颗粒，（e）预测和实验确认可提高各种配方中铝颗粒反应性的方法。除了潜在的技术影响之外，还将制定一项指导计划，让本科生与研究生在研究环境中合作。 此外，纳米颗粒燃烧将被纳入燃烧课程和含能材料继续教育计划中。研究人员还计划在各种国际会议上组织专门讨论“机械化学”过程的专题研讨会。