Linking molecular level chemistry to macroscopic combustion behavior for nano-energetic materials with halogen containing oxides

Coupling molecular scale reaction kinetics with macroscopic combustion behavior is critical to understanding the influences of intermediate chemistry on energy propagation, yet bridging this multi-scale gap is challenging. This study integrates ab initio quantum chemical calculations and condensed p...

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Bibliographic Details
Published in:The Journal of chemical physics 2013-08, Vol.139 (7), p.074701-074701
Main Authors: Farley, Cory W, Pantoya, Michelle L, Losada, Martin, Chaudhuri, Santanu
Format: Article
Language:English
Subjects:
Aluminum
Aluminum oxide
Combustion
Exothermic reactions
Flame speed
Nanostructure
Reaction kinetics
Shells
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Summary:Coupling molecular scale reaction kinetics with macroscopic combustion behavior is critical to understanding the influences of intermediate chemistry on energy propagation, yet bridging this multi-scale gap is challenging. This study integrates ab initio quantum chemical calculations and condensed phase density functional theory to elucidate factors contributing to experimentally measured high flame speeds (i.e., >900 m∕s) associated with halogen based energetic composites, such as aluminum (Al) and iodine pentoxide (I2O5). Experiments show a direct correlation between apparent activation energy and flame speed suggesting that flame speed is directly influenced by chemical kinetics. Toward this end, the first principle simulations resolve key exothermic surface and intermediate chemistries contributing toward the kinetics that promote high flame speeds. Linking molecular level exothermicity to macroscopic experimental investigations provides insight into the unique role of the alumina oxide shell passivating aluminum particles. In the case of Al reacting with I2O5, the alumina shell promotes exothermic surface chemistries that reduce activation energy and increase flame speed. This finding is in contrast to Al reaction with metal oxides that show the alumina shell does not participate exothermically in the reaction.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4818167