Explosive charges with nanoscale aluminum powder, page 1

AFRL successfully produces explosive charges with nanoscale aluminum powder

Scientists successfully incorporated nanoscale aluminum powder into a series of experimental explosives developed at AFRL’s High Explosives Research and Development (HERD) facility. Production issues have plagued nano-particle-containing formulations. Formulation difficulties arise as powders with large surface areas require too much fluid for coating. Therefore, only a small fraction of nanoscale aluminum powder in a formulation causes a cast-cure or melt-cast explosive to become so viscous during mixing that researchers cannot process and load it in the traditional manner. The HERD researchers overcame this issue and produced research-quality pressed charges using molding powders.

Accomplishment
AFRL researchers at the HERD facility achieved a high percentage of theoretical maximum density with a very low variation in density of all the pressed pellets, making an ideal item for fundamental testing. Researchers will utilize these pellets to test the hypothesis that nanoscale particles will accelerate aluminum’s energy release rate to the timescale of an explosive detonation. AFRL completed a contracted effort to develop additional nanoformulations utilizing the laboratory-developed technique. Scientists will conduct fundamental detonics testing in the near future.

Background
Researchers are performing a systematic, phenomenological study to definitively establish the extent to which nanoparticle size can accelerate the combustion rate. In order to conclusively determine the extent of this effect, AFRL is conducting highly repeatable experiments, necessitating the availability of highly consistent precision charges. Both metal acceleration and blast effects are desirable in an explosive. The current generation of explosives uses aluminum that reacts relatively slowly and manifests itself as blast energy. Recent modeling efforts have shown that nanoaluminum powders have the potential to react within the reaction zone of the detonation wave, thus providing useful energy for accelerating metal.

The performance of nanoenergetics has the potential to improve due to a more rapid and complete combustion of the aluminum powder in the nanoformulation (compared to standard formulations using micron-sized aluminum). Scientists expect an increase over micron rates and/or performance due to the drastic increase in the nanoparticles’ surface area.

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[edit on 3-11-2005 by alternate]