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在惰性或氧化性气氛中的燃烧机理，通常是由另一种金属如镍、钛或锆包覆的铝芯。这项研究包括控制单个粒子的点火和燃烧以及反应波在粒子云中传播的基本过程。从微观(单颗粒)和宏观(颗粒云)两个尺度上阐明了颗粒的化学、形态(大小和形状)、浓度以及气相组成对燃烧的影响。为此，开发了基于电动悬浮和电动流态化的先进实验技术。此外，计算机辅助的复杂金属丝的电热成像也被用来获得金属-金属和金属-气体反应的动力学数据。这些数据为考虑金属间反应和固体壳层破裂等特征的复杂金属颗粒燃烧建模提供了基础，这项工作的结果直接关系到在材料合成和推进中的应用。颗粒悬浮液在气体中的燃烧是一种有吸引力的连续生产金属间化合物的方法。与纯铝相比，火箭推进剂中的复杂金属颗粒具有减少团聚和降低点火温度的特点。

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.