Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session C3: Detonation and Shock-Induced Chemistry: Carbon Condensation |
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Chair: Milie Firestone, Los Alamos National Laboratory Room: Grand Ballroom FG |
Monday, July 10, 2017 11:15AM - 11:30AM |
C3.00001: Density Gradient Separation of Detonation Soot for Nanocarbon Characterization Bryan Ringstrand, Katie Jungjohann, Sonke Seifert, Millicent Firestone, David Podlesak Detonation of high explosives (HE) can expand our understanding of chemical bonding at extreme conditions as well as the opportunity to prepare carbon nanomaterials. In order to understand detonation mechanisms, nanocarbon characterization contained within the soot is paramount. Thus, benign purification methods for detonation soot are important for its characterization. Progress towards a non-traditional approach to detonation soot processing is presented. Purification of soot using heavy liquid media such as sodium polytungstate to separate soot components based on their density was tested based on the premise that different nanocarbons possess different densities [$\rho =$ 1.79 g/cm$^{\mathrm{3}}$ (graphene) and $\rho =$ 3.05 g/cm$^{\mathrm{3}}$ (nanodiamond)]. Analysis using XRD, SAXS, WAXS, Raman, XPS, TEM, and NMR provided information about particle morphology and carbon hybridization. Detonation synthesis offers an avenue for the discovery of new carbon frameworks. In addition, understanding reactions at extreme conditions provides for more accurate predictions of HE performance, explosion intent, and simulation refinement. These results are of interest to both the nanoscience and shock physics communities. [Preview Abstract] |
Monday, July 10, 2017 11:30AM - 11:45AM |
C3.00002: Formation Pathways of Carbon Allotropes in Detonation Condensates Michael Nielsen, Michael Bagge-Hansen, Josh Hammons, Lisa Lauderbach, Ralph Hodgin, Sorin Bastea, Larry Fried, Jonathan Lee, Tony van Buuren, Phil Pagoria, Chadd May, Shaul Aloni, Trevor Willey Time-resolved small-angle scattering (TR-SAXS) data reveal evolution in the size and morphology of nano-carbon particles that form during the first microsecond during the detonation of high explosive (HE) materials, but do not provide chemical or phase information. Herein, we present analysis of complementary post-detonation soots collected with minimal environmental carbon or other contamination: HE samples are detonated whithin clean ice capture layers to yield aqueous dispersions of the carbonaceous soot. We report substantial variation in soots formed through the detonation of HE materials that attain a variety of temperatures and pressures during detonation. Transmission electron microscopy analysis of these recovered soots provides physical and chemical information that we compare directly to TR-SAXS data and SAXS measurements from recovered soots. We observe various structures including graphitic and amorphous carbon, nanodiamond, and spherical carbon onions. These experimental data correlate to models of how products from HE materials traverse the carbon phase diagram during detonation. Prepared by LLNL under Contract DE-AC52-07NA27344. [Preview Abstract] |
Monday, July 10, 2017 11:45AM - 12:00PM |
C3.00003: Observation of Carbon Fractionation in HE Debris by Large Geometry Secondary Ion Mass Spectrometry Todd Williamson, David Podlesak, Travis Tenner, Julia Fordham Detonation of high explosives (HE) is an exothermic process producing a variety of simple gaseous molecules (e.g. CO, CO$_{\mathrm{2}}$, N$_{\mathrm{2}}$, H$_{\mathrm{2}}$O) and solid carbon soot. The chemistry of the carbon soot which is formed is influenced by the high pressures ($P)$ and temperatures ($T)$ that are induced by the shock compression that occurs due to the detonation. This can result in isotopic fractionation of the soot as the lighter $^{\mathrm{12}}$C is more likely to participate in reactions forming gaseous products, resulting in $^{\mathrm{13}}$C enriched particulate soot material. Isotopic analysis of HE soot is usually performed at the bulk level of an agglomerated sample, which gives an average value and can obscure trends among individual particles. To study C isotopic fractionation of HE debris at the individual particle level, we have used Large Geometry Secondary Ion Mass Spectrometry (LG-SIMS), which has the ability to deliver in-situ high precision and accuracy isotope ratios of individual particles. This allows for evaluating thousands of individual particles from HE detonations, providing isotopic data at the per particle level. HE debris particles from a variety of detonation conditions ($P$ ranging from 25 -- 85 GPa) have been measured by LG-SIMS showing a general trend of higher $^{\mathrm{13}}$C fractionation with increasing $P$. [Preview Abstract] |
Monday, July 10, 2017 12:00PM - 12:15PM |
C3.00004: Isotopic measurements (C,N,O) of detonation soot produced from labeled and unlabeled Composition B-3 indicate source of solid carbon residues. David Podlesak, Virginia Manner, Ronald Amato, Dana Dattelbaum, Richard Gusavsen, Rachel Huber Detonation of HE is an exothermic process whereby metastable complex molecules are converted to simple stable molecules such as H$_{\mathrm{2}}$O, N$_{\mathrm{2}}$, CO, CO$_{\mathrm{2}}$, and solid carbon. The solid carbon contains various allotropes such as detonation nanodiamonds, graphite, and amorphous carbon. It is well known that certain HE formulations such as Composition B (60{\%} RDX, 40{\%} TNT) produce greater amounts of solid carbon than other more oxygen-balanced formulations. To develop a greater understanding of how formulation and environment influence solid carbon formation, we synthesized TNT and RDX with $^{\mathrm{13}}$C and $^{\mathrm{15}}$N at levels slightly above natural abundance levels. Synthesized RDX and TNT were mixed at a ratio of 60:40 to form Composition B and solid carbon residues were collected from detonations of isotopically-labeled as well as un-labelled Composition B. The raw HE and detonation residues were analyzed isotopically for C, N, O isotopic compositions. We will discuss differences between treatments groups as a function of formulation and environment. LA-UR -- 17-21266 [Preview Abstract] |
Monday, July 10, 2017 12:15PM - 12:30PM |
C3.00005: An experimental characterization of condensed phase soot from overdriven detonations of Composition B Robert Reeves, Garth Egan, Greg Klunder, Sorin Bastea, Riad Manaa An experimental series was undertaken to produce and characterize the reaction products formed during detonation of Composition B under conditions varying from C-J detonation to overdriven conditions. Overdriven conditions were replicated utilizing a two-stage gas gun, in order to provide a supported shock at a continuous pressure for the entirety of the detonation event. Input pressures ranged from 31.3 GPa to 55.0 GPa, and the results were compared to a standard detonation of Composition B at C-J pressures. In all tests, the amount of post-detonation products, gaseous and condensed phase, were quantified. The gaseous products were analyzed for chemical content by mass spectrometry and gas chromatography. The morphology and phase of the soot was analyzed by electron microscopy and x-ray photoelectron spectroscopy. Several trends were identified. The gas generation rate generally increased with input pressure. For condensed phase products, the relative production of graphitic to diamond-like material increased with pressure, but the size of the formed particles seemed to decrease. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
Monday, July 10, 2017 12:30PM - 12:45PM |
C3.00006: Fast emission spectroscopy for monitoring condensed carbon in detonation products of oxygen-deficient high explosives Sandra Poeuf, Gerard Baudin, Marc Genetier, Alexandre Lefrançois, Ashwin Cinnayya, Jacquet Laurent A new thermochemical code, SIAME, dedicated to the study of high explosives, is currently being developed. New experimental data relative to the expansion of detonation products are required to validate the code, and a particular focus is made on solid carbon products. Two different high explosive formulations are used: a melt-cast one (RDX/TNT 60/40 {\%} wt.) and a pressed one (HMX/Viton$^{\mathrm{R}}$ 96/4 {\%} wt.). The experimental setup allows the expansion of the products at pressures below 1 GPa in an inert medium (vacuum, helium, nitrogen and PMMA). The results of fast emission dynamic spectroscopy measurements used to monitor the detonation carbon products are reported. Two spectral signatures are identified: the first is associated to ionized gases and the second to carbon thermal radiation. The experimental spectral lines are compared with simulated spectra. The trajectory of the shock wave front is continuously recorded with a high frequency interferometer. Comparisons with numerical simulations on the hydrodynamic code \textsc{Ouranos }have been done. These two measurements, using the different inert media, enable to make one step forward in the validation of the detonation products equation of state implemented in the SIAME code. [Preview Abstract] |
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