Atomic-scale identification of microexplosion of aluminum nanoparticles as highly efficient oxidation

Abstract

In this work, it was proposed to employ the particle dispersion velocity (νD), pressure, heat release rate, delay time, and the numbers of Al-clusters and Al–O bonds derived from reactive molecular dynamics simulations to atomically identify the microexplosion of Al nanoparticles (ANPs), which is feasible to reduce agglomeration and promote the combustion efficiency in applications. The microexplosion is significantly different from common oxidation in terms of the evolution of morphology, reactivity, and energy, since it can be strengthened with an increase in O2 content and temperature and a decrease in particle size. That is, the microexplosion causes the more rapid increase in νD, pressure, heat release, and the number of Al-clusters and Al–O bonds, and the decrease in delay time compared to common oxidation. Meanwhile, the methods for assessing the intensity of the microexplosion and the promotion effect of the microexplosion on ANP oxidation were successfully established in this work. Importantly, the promotion efficiency was ascertained using the heat release rate (0.05 ​kJ·g−1·ps−1) and the ratio of the number of Al–O bonds to the number of Al atoms at the early stage of oxidation (0–50 ps). This work is expected to present a comprehensive perspective of the oxidation of ANPs in O2 under different O2 content, temperatures, and particle sizes, which may be instructive for other violent oxidation of various metal-based fuel nanoparticles.

Keywords

• Al nanoparticles
• Clusters
• Microexplosion
• Molecular dynamic simulations
• Oxidation