EXPLOSIVE COMPATIONS OF INTERMETALLIC-FORMING POWDER MIXTURES FOR FABRICATING STRUCTURAL ENERGETIC MATERIALS

AbstractUltra-fast reactions initiated within or immediately behind the shock front in powder mixtures are of importance in the synthesis of high-pressure phases and next-generation energetic materials. Reactions in nickel and aluminum powder mixtures and the establishment of a reaction threshold have been the source of many studies over the last 20 years. Prior work has suggested that the criterion for reaction is most probably mechanochemical in nature, in which shock loading environment plays a larger role than absolute shock energy input. The mechanisms responsible for intimate mixing of fresh reactants are however still unclear. In this work we are investigating the role of particle size and morphology on the loading, mixing, and their subsequent shock-induced reaction behavior, by performing shock-compressibility experiments on equi-volumetric mixtures of nickel and aluminum powders, with variations in nickel particle size (micron and nano-scale) and shape (spherical and flake). Determination of shock states is accomplished through time-resolved in situ PVDF gauge measurements of input shock stress and shock propagation speed obtained from transit time through the thickness of powder mixture. The reaction product shock-compressibility state is also being calculated based on constant pressure approximations to allow correlation with measured states for inference of the occurrence of shock-induced chemical reactions. The results of this study suggest that powder configuration in the nickel-aluminum system can be modified to encourage or discourage reaction.

Download Full-text

EQUATION OF STATE & FAILURE CRITERIA OF DUAL FUNCTIONAL STRUCTURAL ENERGETIC MATERIALS

10.1063/1.2832971 ◽

2008 ◽

Author(s):

S. Hanagud ◽

X. Lu ◽

R. Zaharieva ◽

Mark Elert ◽

Michael D. Furnish ◽

...

Keyword(s):

Equation Of State ◽

Energetic Materials ◽

Failure Criteria ◽

State Failure ◽

Dual Functional ◽

Structural Energetic Materials

Download Full-text

A Comparison of Different Ni+Al Structural Energetic Materials

MRS Proceedings ◽

10.1557/opl.2013.48 ◽

2013 ◽

Vol 1521 ◽

Cited By ~ 2

Author(s):

B. Aydelotte ◽

N.N. Thadhani

Keyword(s):

Energetic Materials ◽

Impact Tests ◽

Reactive Materials ◽

Microstructure Morphology ◽

Structural Energetic Materials

AbstractA comparison of different Ni+Al reactive materials is conducted to elucidate the effects of microstructure morphology on performance. CTH, a multi-material Eulerian hydrocode, was utilized to study mesoscale deformation during simulated rod-on-anvil experiments. It is found that the cold sprayed Ni+Al, which has a more topologically connected nickel phase, is likely to be more reactive because of enhanced deformation in the Ni phase relative to explosively compacted Ni+Al, where the Ni phase undergoes less deformation. Rod-on-anvil impact tests verify that cold sprayed Ni+Al is indeed more reactive than explosively compacted Ni+Al when subject to impact.

Download Full-text