TY - JOUR
T1 - Reactive wave propagation in energetic porous silicon composites
AU - Parimi, Venkata Sharat
AU - Bermúdez Lozda, Alfredo
AU - Tadigadapa, Srinivas A.
AU - Yetter, Richard A.
N1 - Funding Information:
The authors gratefully acknowledge the support and funding from the Defense Threat Reduction Agency (DTRA), Counter-WMD basic research program, under Grant Number HDTRA1-08-1-0006 and from the National Science Foundation under Grant Number EEC-1062984 . This publication was supported by the Pennsylvania State University Materials Research Institute Nanofabrication Lab and the National Science Foundation Cooperative Agreement No. ECS-0335765. The authors wish to thank Julie Anderson and Lymaris Ortiz Rivera from the Materials Characterization Laboratory (MCL) at The Pennsylvania State University for help with gas adsorption measurements.
Publisher Copyright:
© 2014 The Combustion Institute.
PY - 2014
Y1 - 2014
N2 - A parametric study of reactive wave propagations in porous silicon (PS) - oxidizer composites is presented. This study investigates the effects of the composite equivalence ratio and the oxidizer, and also the nanoscale and microscale structure, and the effect of dopant atoms, which are specific to this nanostructured composite material. The reactive wave speed and structure for energetic PS composites formed by depositing sodium, magnesium, or calcium perchlorates within the nanoscale pores were analyzed with high speed video recordings and spectroscopic temperature measurements. The findings indicate that heavily doped samples that do not yield a microscale structure result in slow propagation speeds, and low doped substrates with randomly formed micro-crack patterns during the electrochemical dissolution result in high speed propagations. A systematic study of the mixture composition revealed very wide flammability limits and flame speed and temperature measurements independent of the equivalence ratio, consistent with thermochemical equilibrium calculations. Also, while all the composites considered in this study are fuel rich with equivalence ratios greater than 1.60, the composites with equivalence ratios closer to unity exhibited lower temperatures and propagation speeds than more fuel rich composites. This unusual behavior of the composites is attributed to the inhomogeneity of the system even though the reactants are mixed at the nanometer scale. This was illustrated by developing a phenomenological model describing the interaction of silicon and the oxidizer within a single nanometer scale pore, which revealed that the reactive wave propagation is more strongly controlled by the specific surface area than the global equivalence ratio, due to the diffusion length scales involved.
AB - A parametric study of reactive wave propagations in porous silicon (PS) - oxidizer composites is presented. This study investigates the effects of the composite equivalence ratio and the oxidizer, and also the nanoscale and microscale structure, and the effect of dopant atoms, which are specific to this nanostructured composite material. The reactive wave speed and structure for energetic PS composites formed by depositing sodium, magnesium, or calcium perchlorates within the nanoscale pores were analyzed with high speed video recordings and spectroscopic temperature measurements. The findings indicate that heavily doped samples that do not yield a microscale structure result in slow propagation speeds, and low doped substrates with randomly formed micro-crack patterns during the electrochemical dissolution result in high speed propagations. A systematic study of the mixture composition revealed very wide flammability limits and flame speed and temperature measurements independent of the equivalence ratio, consistent with thermochemical equilibrium calculations. Also, while all the composites considered in this study are fuel rich with equivalence ratios greater than 1.60, the composites with equivalence ratios closer to unity exhibited lower temperatures and propagation speeds than more fuel rich composites. This unusual behavior of the composites is attributed to the inhomogeneity of the system even though the reactants are mixed at the nanometer scale. This was illustrated by developing a phenomenological model describing the interaction of silicon and the oxidizer within a single nanometer scale pore, which revealed that the reactive wave propagation is more strongly controlled by the specific surface area than the global equivalence ratio, due to the diffusion length scales involved.
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U2 - 10.1016/j.combustflame.2014.05.005
DO - 10.1016/j.combustflame.2014.05.005
M3 - Article
AN - SCOPUS:84926278269
VL - 161
SP - 2991
EP - 2999
JO - Combustion and Flame
JF - Combustion and Flame
SN - 0010-2180
IS - 11
ER -