Bulletin of the American Physical Society
18th Biennial Intl. Conference of the APS Topical Group on Shock Compression of Condensed Matter held in conjunction with the 24th Biennial Intl. Conference of the Intl. Association for the Advancement of High Pressure Science and Technology (AIRAPT)
Volume 58, Number 7
Sunday–Friday, July 7–12, 2013; Seattle, Washington
Session K5: EM.2 Nonconventional Energetic Materials |
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Chair: Virginia Manner, Los Alamos National Laboratory Room: Cascade I |
Tuesday, July 9, 2013 1:45PM - 2:00PM |
K5.00001: Shock Initiation and Equation of State of Ammonium Nitrate David Robbins, Steve Sheffield, Dana Dattelbaum, Raja Chellappa, Nenad Velisavljevic Ammonium nitrate (AN) is a widely used fertilizer and mining explosive commonly found in ammonium nitrate-fuel oil. Neat AN is a non-ideal explosive with measured detonation velocities approaching 4 km/s. Previously, we reported a thermodynamically-complete equation of state for AN based on its maximum density, and showed that near-full density AN did not initiate when subjected to shock input conditions up to 22 GPa. In this work, we extend these initial results, by presenting new Hugoniot data for intermediate density neat AN obtained from gas gun-driven plate impact experiments. AN at densities from 1.8 to 1.5 g/cm3 were impacted into LiF windows using a two-stage light gas gun. Dual VISARs were used to measure the interfacial particle velocity wave profile as a function of time following impact. The new Hugoniot data, in addition to updates to thermodynamic parameters derived from structural analysis and vibrational spectroscopy measurements in high pressure diamond anvil cell experiments, are used to refine the unreacted EOS for AN. Furthermore, shock initiation of neat AN was observed as the initial porosity increased (density decreased). Insights into the relationship(s) between initial density and shock initiation sensitivity are also presented, from evidence of shock initiation in the particle velocity profiles obtained for the lower density AN samples. [Preview Abstract] |
Tuesday, July 9, 2013 2:00PM - 2:15PM |
K5.00002: Phase Diagram of Ammonium Nitrate Mihindra Dunuwille, Choong- Shik Yoo Ammonium Nitrate (AN) has often been subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood - resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety, in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN, in different chemical environments, at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 15 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 673 K. 1. Stephens, H. W. The Texas City disaster, 1947. Austin, TX: University of Texas Press. 1997 2. Alistair, J. D. et al., J. Phys. Chem. A 2011, 115, 11889; Dunuwille, M. et al., J. Phys. Chem. A 2012, 116, 7600. [Preview Abstract] |
Tuesday, July 9, 2013 2:15PM - 2:30PM |
K5.00003: Detonation behavior of emulsion explosives sensitized with polymeric microballoons Ricardo Mendes, Jos\'e Ribeiro, Igor Plaksin, Jos\'e Campos The differences between the detonation behavior of ammonium nitrate based emulsion explosive sensitized with polymeric or with glass microballoons is presented and discussed. Expancel$^{\textregistered}$ are hollow polymeric microballoons that contain a hydrocarbon gas. The mean particle size of those particles is 30 $\mu $m and their wall thickness is about 0.1 $\mu $m. The detonation velocity and the failure diameter of the emulsion explosive sensitized with different amounts of these particles were measured, in cylindrical charges, by ionization pins and optical fibers. The detonation velocity of emulsion explosives shows a non-monotonic evolution with the density with the maximum being reached far below the maximum density. The detonation fails when the density approaches the one of the matrix. The failure diameter increases with increasing density. For low densities the detonation velocity is almost independent of the charge diameter and it is close to the values predict by BKW EoS. The effect of the nature and size of the microballoons on the detonation front curvature and failure diameter was also determined. [Preview Abstract] |
Tuesday, July 9, 2013 2:30PM - 2:45PM |
K5.00004: Carbon solids in oxygen-deficient explosives (LA-UR-13-21151) Travis Peery The phase behavior of excess carbon in oxygen-deficient explosives has a significant effect on detonation properties and product equations of state. Mixtures of fuel oil in ammonium nitrate (ANFO) above a stoichiometric ratio demonstrate that even small amounts of graphite, on the order of 5{\%} by mole fraction, can substantially alter the Chapman-Jouget (CJ) state properties, a central ingredient in modeling the products equation of state. Similar effects can be seen for Composition B, which borders the carbon phase boundary between graphite and diamond. Nano-diamond formation adds complexity to the product modeling because of surface adsorption effects. I will discuss these carbon phase issues in our equation of state modeling of detonation products, including our statistical mechanics description of carbon clustering and surface chemistry to properly treat solid carbon formation. [Preview Abstract] |
Tuesday, July 9, 2013 2:45PM - 3:00PM |
K5.00005: Pressure waves generated by metastable intermolecular composites in an aqueous environment Geoff Maines, Matei Radulescu, Antoine Bacciochini, Bertrand Jodoin, Julian Lee In the present study, pressure waves generated by a metastable intermolecular composite (MIC) have been measured experimentally in an aqueous environment. Experiments were performed in a 1.0 L high pressure chamber mounted with high resolution pressure transducers and designed with optical access. Samples consisting of a stoichiometric mixture of aluminum and copper(II)oxide particles were evaluated. Two types of samples were constructed; a mixture of micron-sized raw powders, and ball milled powders with a lamellated nanostructure. A planetary mill was used to refine reactant powders from micron- to nano-scale dimensions. Manual compaction and cold spray deposition techniques were used to consolidate powders in various densities. The dynamics of the pressure wave and high pressure gas bubble were monitored via pressure data and high-speed Schlieren visualization. The effects of reactant particle size and sample density have been evaluated quantitatively and compared with equilibrium calculations. Dynamics of the pressure wave were correlated with the amount of gas released and the rate of burning of the sample material. [Preview Abstract] |
Tuesday, July 9, 2013 3:00PM - 3:15PM |
K5.00006: Nano-Scale Energetic Films by Superfluid Helium Droplet Assembly Samuel Emery, Jason Boyle, Keith Rider, Brian Little, C. Michael Lindsay, Amanda Schrand We have recently transitioned superfluid helium droplet assembly of clusters into a deposition tool that is capable of creating nano-structured films of composite metal-based energetic materials (EM). Such materials are ideal candidates to study propagation of reactions at small scale, and could be alternatives to organic based EM due to their higher energy densities. The helium droplet methodology may also provide a solution overcoming issues of reaction-limiting effects such as the formation of oxide layers by exploiting `magic-number' cluster sizes and core-shell cluster mechanisms. This presentation will describe the following: foundational work to model and characterize the deposition of magnesium clusters by superfluid helium droplet assembly, our efforts to produce magnesium-Fomblin core-shell EM cluster-based films on a surface, and our early attempts at making intermetallic cluster-based films. [Preview Abstract] |
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