Combustion Mechanisms of Complex Metal Particles

这项工作的目的是建立由两种不同金属组成的复杂金属颗粒的燃烧机制，通常是铝芯被另一种金属（如镍、钛或锆）覆盖，在惰性或氧化气氛中。该研究包括控制单个颗粒点火和燃烧的基本过程以及颗粒云中反应波的传播。在微观（单个颗粒）和宏观（颗粒云）尺度上阐明了对燃烧的化学、形态（大小和形状）、颗粒浓度以及气相组成的影响。为此，开发了基于电动力悬浮和电动力流化的先进实验技术。此外，复杂金属丝的计算机辅助电热成像用于获得金属-金属和金属-气体反应的动力学数据。这些数据为模拟复杂金属颗粒的燃烧提供了基础，并考虑了金属间反应和固体壳裂等特征。这项工作的结果与材料合成和推进的应用直接相关。在气体中燃烧颗粒悬浮液是一种有吸引力的连续生产金属间化合物的方法。火箭推进剂中的复杂金属颗粒比纯铝的结块更少，点火温度更低。

The objective of this work is to establish the mechanisms of combustion of complex metal particles consisting of two different metals, typically an aluminum core covered by another metal such as nickel, titanium or zirconium, in inert or oxidizing atmospheres. The study includes the fundamental processes that control ignition and combustion of single particles and propagation of reaction waves in clouds of particles. Influences on combustion of chemistry, morphology (size and shape), and concentration of particles, as well as composition of the gas phase, are clarified on both the microscopic (single particle) and macroscopic (particle cloud) scales. To do this, advanced experimental techniques are developed based on electrodynamic levitation and electrodynamic fluidization. Also, computer-assisted electrothermography of complex metal wires is used to obtain kinetic data on metal-metal and metal-gas reactions. These data provide a basis for modeling combustion of complex metal particles, accounting for such characteristics as intermetallic reactions and cracking of solid shells.The results of this work are directly relevant for applications in both materials synthesis and propulsion. Combustion of particle suspensions in gas is an attractive method for continuous production of intermetallic compounds. Complex metal particles in rocket propellants offer reduced agglomeration and lower ignition temperature than pure aluminum.