Atomistic insights into two-stage combustion of a single boron nanoparticle via reactive molecular dynamics

MY Feng and Y Wang and DY Hou and HP Li and KH Luo and XF Xu, FUEL, 375, 132628 (2024).

DOI: 10.1016/j.fuel.2024.132628

Boron (B) is a promising energetic additive for high-energy fuels, but its poor ignition and combustion characteristics limit its application in practical systems. The nano-sized B could alleviate these problems to a large extent. In this study, a reactive molecular dynamics simulation method is employed to investigate the fundamental combustion mechanisms of a single B nanoparticle (BNP). The experimentally observed two-stage combustion is reproduced. Moreover, the first stage is further divided into the pre-heating stage and the fast evaporation stage. The second stage is dominated by the B core combustion, during which a dynamic equilibrium of the interfacial layer and the oxide/evaporation layer is reached and drives the reaction. The diffusion mechanism of the BNP combustion is revealed. The evaporation of oxides and diffusion of ambient oxygen species into the oxide/evaporation layer proceed simultaneously during the fast evaporation stage. No ambient oxygen species diffuse into the B core but the diffusion of the core B atoms into the oxide/evaporation layer occurs throughout the simulation. Additionally, the diffusion of the core B atoms is enhanced with the rising temperature. Consistent with experimental results, BO2 2 is found to be a dominant intermediate species during the combustion. Furthermore, our new finding is that B3O4 3 O 4 is also an important intermediate, which bridges the conversion of larger BxOy x O y species to the main combustion product B2O3. 2 O 3 . The new atomistic insights obtained from the present research could potentially benefit the design and practical application of nano-sized B as additives for high-energy fuels.

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