Bulletin of the American Physical Society
2005 14th APS Topical Conference on Shock Compression of Condensed Matter
Sunday–Friday, July 31–August 5 2005; Baltimore, MD
Session Z1: Energetic Materials IX |
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Chair: Suhithi Peiris, Naval Surface Warfare Center, Indian Head Room: Hyatt Regency Constellation B |
Friday, August 5, 2005 10:30AM - 11:00AM |
Z1.00001: Processing, application and characterization of ultrafine and nanometric materials in energetic compositions Invited Speaker: The energetic materials research at TNO Defence, Security and Safety, The Netherlands is focusing at the development and characterization of explosives (insensitive munitions), gun/rocket propellants and pyrotechnic compositions and their ingredients. The application of reactive, ultrafine and nanometric materials in these compositions has gained increased interest over the past few years. Current research topics focus on the processing, application and characterization of (1) ultrafine energetic crystals and composite nano-clusters in plastic bonded explosives, (2) metastable intermolecular composites (MICs) and (3) self-propagating high-temperature synthesis (SHS). In this paper several of these topics will be highlighted in more detail. [Preview Abstract] |
Friday, August 5, 2005 11:00AM - 11:15AM |
Z1.00002: Preparation and Shock Reactivity Analysis of Novel Perfluoroalkyl-Coated Aluminum Nanocomposites. R. Jason Jouet, Joel Carney, Richard Granholm, Harold Sandusky, Andrea Warren The energy content of current and future explosive and propellant formulations can be increased by elimination of the parasitic oxide present on conventional Al as well as utilization of fluorine as the oxidizer to make Al-F species. Removal of the oxide passivation layer on Al particles will result in an enhancement of the rate of Al combustion. Additional reaction rate enhancement should result from close proximity of the oxidizer and fuel species. Therefore, passivation of Al nanoparticles with molecules containing oxidizer species should produce a final material capable reacting fast enough so the accompanying energy release can contribute to the detonation wave produced by explosive formulations. Passivation of unpassivated, oxide-free aluminum nanoparticles using C$_{13}$F$_{27}$COOH is reported with materials containing as much as 32.95 {\%} Al. Characterization data, including SEM, TGA, and ATR-FTIR, indicate that the C$_{13}$F$_{27}$COOH molecule binds to the surface of the Al particle protecting the surface from oxidation in ambient air. Small Scale Shock Reactivity Test (SSRT) results of the Al-C$_{13}$F$_{27}$COOH material formulated with HMX will be presented. [Preview Abstract] |
Friday, August 5, 2005 11:15AM - 11:30AM |
Z1.00003: Strategies for Tuning the Reactivity of NanoEnergetic Materials Anand Prakash, Soo Kim, Alon McCormick, Michael Zachariah Nanostructured fuel/oxidizer composites are being looked upon as a possible approach to enhance energy release rates. Here we report on two approaches to moderate/tune reactivity. In the first example we accelerate reactivity. The method is based on electrostatically enhanced assembly to promote the preferential arrangement of aluminum (fuel) nanoparticles with iron oxide (oxidizer) nanoparticles in the aerosol phase. Two unipolar chargers are employed to generate oppositely charged aluminum and iron oxide particles, which enhance the formation of intimately interconnected nanocomposite energetic materials. The results of burning tests and thermal analysis using differential scanning calorimetry (DSC) showed that aluminum/iron oxide nanocomposite aerosol materials synthesized by bipolar assembly had burning rates that are a factor of 10 higher than those produced by random Brownian coagulation. In a second approach we employ a very reactive oxidizer (Potassium permanganate; $\sim $150 nm) and create a less reactive shell (Iron oxide). The measured reactivity for a nano-Al/composite oxidizer could be varied by more than a factor of 10 as measured by the pressurization rate in a closed vessel (Psi/microsecond), by changing the coating thickness of the iron oxide. The composite oxidizer nanoparticles were synthesized by a new aerosol approach, where the non-wetting interaction between iron oxide and molten potassium permanganate aids the phase segregation of a nanocomposite droplet into a core-shell structure. [Preview Abstract] |
Friday, August 5, 2005 11:30AM - 11:45AM |
Z1.00004: Nano-Al Reaction with Nitrogen in the Burn Front of Oxygen-Free Energetic Materials Bryce Tappan, Steven Son, David Moore Nano-particulate aluminum metal was added to the high nitrogen energetic materials dihydrazinotetrazine (DHT) and triaminoguanidium azotetrazolate (TAGzT) in order to determine the effects on decomposition behavior. Standard safety testing (sensitivity to impact, spark and friction) are reported, show that the addition of nano-Al actually decreases the sensitivity of the pure DHT and TAGzT. Thermo-equilibrium calculations (Cheetah) indicate that the all of the Al reacts to form AlN in both materials at the levels of interest, and the calculated specific impulses are reported. Emission spectra were collected to determine AlN formation in combustion. Burning rates were also collected, and the effects of nano-Al on rates are discussed. [Preview Abstract] |
Friday, August 5, 2005 11:45AM - 11:59AM |
Z1.00005: Electrical Conductivity Measurements in Reacting Metastable Intermolecular Composites Blaine Asay, Douglas Tasker, James King, Victor Sanders, Steven Son Metastable Intermolecular Composite (MIC) materials are comprised of a mixture of oxidizer and fuel with particle sizes in the nanometer range. To better understand the reaction mechanisms of burning MIC materials, dynamic electrical conductivity measurements have been performed on a MIC material for the first time. Simultaneous optical measurements of the wave front position have shown that the reaction and conduction fronts are coincident within 160~$\mu $m. Unlike detonating high explosives (HE) where the conductivity profile is represented by an initial peak, followed by an exponential decay of conductivity,\cite{} the MIC conductivity profile is a gradual, irregular ramp which increases from zero over many microseconds. This suggests that the reaction zone thickness is different in MICs compared to detonating HE. Static measurements of conductivity of pressed MIC pellets suggest that the conduction is associated with chemical reaction in the MIC. [Preview Abstract] |
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