Reactive molecular dynamics study on the fluorination combustion mechanism of Al particles in CF4

Combustion of Al in F-containing oxidants possesses some attractive advantages on improving combustion efficiency; however, the mechanism therein has not been fully clarified yet. This study employs reactive molecular dynamics simulations to elucidate the fluorination combustion mechanism of Al particles in differently densed CF4. As a result, the fluorination proceeds along Al + CF4 → small AlxFy + C cluster and Al + CF4 → small CxFy + CxAlyFz cluster in low and high densed CF4 air, respectively. Additionally, the microscopic C deposition is revealed with multiple stages, including F abstraction, C2 formation, C chains aggregation, branching, cyclization and ring densification, and fused-ring folding. The C-containing products convert from aluminum carbide clusters to amorphous C as the CF4 density increases. Finally, an F/Al molar ratio of 1.5 exhibits the most energy release of unit mass. This study is expected to deepen the understanding of the fluorination combustion mechanism of Al and provide theoretical guidance for improving combustion efficiency.