TY - JOUR

T1 - The effect of size distribution on burn rate in nanocomposite thermites

T2 - A probability density function study

AU - Granier, John J.

AU - Pantoya, Michelle L.

N1 - Funding Information:
The authors would like to acknowledge the support of the National Science Foundation under grant number CTS-0210141 and our programme manager, Dr Farley Fisher. We are also grateful for support provided by the Army Research Office under grant number DAAD19-02-1-0214 and our ARO programme manager, Dr David Mann. The authors would also like to thank Dr Benjamin Shaw for discussions leading to the inspiration for this work.

PY - 2004/9

Y1 - 2004/9

N2 - Burn rates of thermites are typically calculated in terms of an average particle size that characterizes the bulk mixture. As the particle diameter approaches the nano-scale the burn rate calculation becomes increasingly sensitive to changes in the particle diameter. In this study, burn rate estimates for nano-scale particle composite thermites are statistically evaluated in terms of an integral that employs a probability density function (pdf) for particle size distribution and a diameter dependent burn rate equation. It is shown that the burn rates depend sensitively on the mean particle diameter and the particle size distribution. Both single mode and bimodal particle size distributions were studied. The analysis shows that as the particle size is reduced to the nano-scale, the size distribution, rather than the average particle size alone, becomes increasingly important. Large variability in burn rate is associated with large standard deviations in particle size. Combining nano-scale with bulk-scale particles in a bimodal distribution does not significantly increase the burn rate as compared to a composite consisting of strictly nanoparticles. The results presented here suggest that better reproducibility of the burn rate may be achieved experimentally by selecting a material with a narrow particle size distribution.

AB - Burn rates of thermites are typically calculated in terms of an average particle size that characterizes the bulk mixture. As the particle diameter approaches the nano-scale the burn rate calculation becomes increasingly sensitive to changes in the particle diameter. In this study, burn rate estimates for nano-scale particle composite thermites are statistically evaluated in terms of an integral that employs a probability density function (pdf) for particle size distribution and a diameter dependent burn rate equation. It is shown that the burn rates depend sensitively on the mean particle diameter and the particle size distribution. Both single mode and bimodal particle size distributions were studied. The analysis shows that as the particle size is reduced to the nano-scale, the size distribution, rather than the average particle size alone, becomes increasingly important. Large variability in burn rate is associated with large standard deviations in particle size. Combining nano-scale with bulk-scale particles in a bimodal distribution does not significantly increase the burn rate as compared to a composite consisting of strictly nanoparticles. The results presented here suggest that better reproducibility of the burn rate may be achieved experimentally by selecting a material with a narrow particle size distribution.

UR - http://www.scopus.com/inward/record.url?scp=4644324427&partnerID=8YFLogxK

U2 - 10.1088/1364-7830/8/3/007

DO - 10.1088/1364-7830/8/3/007

M3 - Article

AN - SCOPUS:4644324427

VL - 8

SP - 555

EP - 565

JO - Combustion Theory and Modelling

JF - Combustion Theory and Modelling

SN - 1364-7830

IS - 3

ER -