Molecular dynamics study of thermochemical behaviour of nickel-coated aluminium nanoparticles

Abstract

Aluminium powder has been widely used as a fuel component in solid propellants for rocket motor applications, because of their high heat of combustion and high energy density. Nano-sized aluminium particles have shown promise for enhanced performance over the micron-sized particles owing to high surface to volume ratio. However, aluminium nanoparticles appear to often agglomerate on or near the propellant burning surface. Agglomeration of aluminium particles leads to lower combustion efficiency, slag accumulation, and higher two-phase flow losses, as the combustion products are accelerated through the rocket nozzle. To prevent agglomeration, a thin nickel coating on aluminium nanoparticles surface can be used. Further, the nickel coating prevents the formation of a passivating oxide layer on aluminium, which can cause ignition delay and a slow rate of energy release, as well as reducing energy density due to the presence of non-reactive aluminium oxide content in the particle. Thus, it is important to understand the molecular behaviour between aluminium and nickel, when aluminium is coated with nickel. In this work, we employ molecular dynamics simulations, to study the interactions of nickel-aluminium nanoparticles. A comprehensive evaluation of the thermochemical behaviour of nickel coated aluminium nanoparticle is carried out in this work. The parameters evaluated numerically have been compared with available molecular dynamics data as well as with theoretical predictions obtained from alternative methods.