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 O7: EM.2 Nonconventional Energetics: Intermetallics |
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Chair: Bryce Tappan, Los Alamos National Laboratory Room: Grand Crescent |
Wednesday, July 10, 2013 9:15AM - 9:30AM |
O7.00001: Impact Ignition and Combustion Behavior of Amorphous Metal-Based Reactive Composites Lori Groven, Benjamin Mason, Steven Son Recently published molecular dynamic simulations have shown that metal-based reactive powder composites consisting of at least one amorphous component could lead to improved reaction performance due to amorphous materials having a zero heat of fusion, in addition to having high energy densities and potential uses such as structural energetic materials and enhanced blast materials. In order to investigate the feasibility of these systems, thermochemical equilibrium calculations were performed on various amorphous metal/metalloid based reactive systems with an emphasis on commercially available or easily manufactured amorphous metals, such as Zr and Ti based amorphous alloys in combination with carbon, boron, and aluminum. Based on the calculations and material availability material combinations were chosen. Initial materials were either mixed via a Resodyn mixer or mechanically activated using high energy ball milling where the microstructure of the milled material was characterized using x-ray diffraction, optical microscopy and scanning electron microscopy. The mechanical impact response and combustion behavior of select reactive systems was characterized using the Asay shear impact experiment where impact ignition thresholds, ignition delays, combustion velocities, and temperatures were quantified, and reported. [Preview Abstract] |
Wednesday, July 10, 2013 9:30AM - 9:45AM |
O7.00002: Study of thermite mixtures consolidated by cold gas dynamic spray process Antoine Bacciochini, Geoffrey Maines, Christian Poupart, Matei Radulescu, Bertrand Jodoin, Julian Lee The present study focused on the cold gas dynamic spray process for manufacturing finely structured energetic materials with high reactivity, vanishing porosity, as well as structural integrity and arbitrary shape. The experiments have focused the reaction between the aluminum and metal oxides, such as Al-CuO and Al-MoO$_{3}$ systems. To increase the reactivity, an initial mechanical activation was achieved through interrupted ball milling. The consolidation of the materials used the supersonic cold gas spray technique, where the particles are accelerated to high speeds and consolidated via plastic deformation upon impact, forming activated nano-composites in arbitrary shapes with close to zero porosity. This technique permits to retain the feedstock powder micro-structure and prevents any reactions during the consolidation phase. Reactivity of mixtures has been investigated through flame propagation analysis on cold sprayed samples and compacted powder mixture. Deflagration tests showed the influence of porosity on the reactivity. [Preview Abstract] |
Wednesday, July 10, 2013 9:45AM - 10:00AM |
O7.00003: ABSTRACT WITHDRAWN |
Wednesday, July 10, 2013 10:00AM - 10:15AM |
O7.00004: Shock compression response of Ti+B reactive powder mixtures Manny Gonzales, Ashok Gurumurthy, Gregory Kennedy, Arun Gokhale, Naresh Thadhani The shock compression response of Ti+2B (1:2 Ti:B stoichiometric ratio) reactive powder mixtures at $\sim$ 50\% theoretical material density (TMD) is investigated for shock pressures up to 5 GPa to investigate the possible shock-induced chemical reactivity of this highly exothermic mixture. The shock adiabat is produced from instrumented parallel-plate gas-gun impact experiments on encapsulated powders using poly-vinylidene fluoride (PVDF) stress gauges to measure the input and propagated stress and wave speed in the powder. The shock compression regime is probed from crush-up to full density and onward to assess the potential onset of a shock-induced chemical reaction event in the powder mixture. A series of two-dimensional continuum meso-scale simulations on real and simulated microstructures are performed to predict the shock compression response and identify the meso-scale mechanics that is essential for the so-called ``ballotechnic'' reaction. These meso-scale mechanics are investigated through stereological evolution metrics that track particle interface evolution and their respective field variables. The suitability of the synthetic microstructural representations is evaluated by comparing the experimental and predicted pressure traces. [Preview Abstract] |
Wednesday, July 10, 2013 10:15AM - 10:30AM |
O7.00005: Microstructural Effects on the Reactivity of Nano-Aluminum/Iodine (V) Oxide Films B.K. Little, E.J. Welle, L.M. Martinez, J.C. Nittinger, M.B. Bogle, S.B. Emery, C.M. Lindsay, A.M. Schrand Recent efforts investigating the self-ignition mechanism of nanoaluminum blended with iodine (V) oxide in the form of powders with and without additives suggests that ignition begins below the decomposition point of either reactant and takes place at the alumina shell surrounding the aluminum nanoparticle. As observed in previous studies of powder composites, microstructural features such as particle morphology are expected to strongly influence properties that govern the combustion behavior of this energetic material (EM). In this study, highly reactive composites containing amorphous and/or crystalline iodine oxide and micron/nano-sized Al was blended with an additive and deposited as films. Physiochemical techniques such as thermal gravimetric analysis, scanning calorimetry, X-ray diffraction, electron microscopy, high-speed imaging and planar doppler velocimetry were employed to characterize these EMs with emphasis on correlating the reaction rate (burn rate) with inherent microstructural features (porosity, thickness, TMD, etc). This work was a continuation of efforts to probe the self-ignition mechanism of Al-iodine (V) oxide composites. [Preview Abstract] |
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