Self-Heating Model of Spherical Aluminum Nanoparticle Oxidation

Abstract

Aluminum-oxygen reaction is important in highly energetic and high pressure generating systems. Nanoenergetic thermites include mixtures of nanostructured Al and oxidizer particles. The main distinguishing features of these reactive systems are their significant enthalpy release and tunable rate of energy discharge, which gives rise to a wide range of combustion rates, energy release, and ignition sensitivity. In this paper, we consider rapid oxidation of a spherically symmetric aluminum particle. We use the Cabrera Mott oxidation model to describe the kinetics of oxide growth of an aluminum nanoparticle and to predict reaction temperature and oxidation time. We assume that aluminum particle of diameter 10 to 50 nm is covered by a thin oxide layer (1-4 nm) and is surrounded by abundant amount of oxygen stored by oxidizers. The particle is rapidly heated up to ignition temperature to initiate self-sustaining oxidation reaction as a result of highly exothermic reaction. We numerically investigated the oxidation model by using COMSOL multiphysics software. The software creates a mesh fitted to geometric configuration of a nanoparticle, and performs finite element method computations.