Bulletin of the American Physical Society
19th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 60, Number 8
Sunday–Friday, June 14–19, 2015; Tampa, Florida
Session J2: Energetic and Reactive Materials V: Materials by Design I |
Hide Abstracts |
Chair: Thomas Klapoetke, Ludwig-Maximilians-Universitaet Muenchen, Samuel Emery, Naval Surface Warfare Center, Indian Head Room: Grand F |
Tuesday, June 16, 2015 11:15AM - 11:45AM |
J2.00001: Synthesis of Advanced Energetic Materials Invited Speaker: Rebecca Wilson For a given energetic material, performance is a combination of the rate of energy release and total energy content. Organic and metal-based energetics, respectively, represent the limiting cases, exhibiting strength in one area and weakness in the other. Many organic energetic materials readily detonate, but increasing total energy content using only known energetic functional groups is difficult. In contrast, combustion of aluminum metal can release more than three times the energy available from the same mass of organic explosive, but the rate of energy release is slow relative to detonation, and combustion is often incomplete. Current research in our department seeks to improve both the total energy content of organic explosives and the rate of combustion of aluminum-based materials. Novel arrangements of atoms within energetic molecules, along with new assembly methods for materials, are employed to improve both aspects of performance. In the case of organic energetic materials, novel functional groups can yield compounds with higher density, and therefore greater power, relative to conventional, nitro group-based materials. For aluminum-based materials, progressively smaller particles undergo more rapid and complete combustion. To prevent surface oxidation, one approach is to shield a core of low-valent aluminum atoms with a shell of ligands, while another is to develop aluminum-based fuels that are inherently air-stable. These methods will be discussed in the context of novel energetic materials synthesis. [Preview Abstract] |
Tuesday, June 16, 2015 11:45AM - 12:00PM |
J2.00002: Microexplosive Metallized Fuels for Energetic Materials Brandon Terry, Mario Rubio, Ibrahim Gunduz, Steven Son Microexplosions have been widely investigated for multicomponent liquid fuels. This phenomenon is caused by internal bubble nucleation and growth from within a fuel droplet (i.e., intraparticle boiling), which induces droplet fragmentation. Microexplosive fuels are advantageous as they promote fuel atomization, which can reduce residence times, increase completeness of combustion, and reduce product agglomeration (if condensed phase products are formed). While this is well understood and utilized with liquid fuels, it has not been fully investigated for metallic fuel particles. Recent work has shown that mechanical activation of aluminum/polymer (inclusion) composites can also cause microexplosions, analogous to liquid emulsion fuels. Gases are produced when the polymer within the composite decomposes below the boiling point of aluminum, causing the composite particle to shatter into smaller particles. Here we show that fully metallic multicomponent fuels (e.g., Al-Li alloy) can also microexplode during combustion and compare this to inclusion composite ignition. Because the two components have a large disparity in boiling points, intraparticle boiling causes the particle to expand and eventually shatter the fuel particle, analogous to missive liquid fuels. [Preview Abstract] |
Tuesday, June 16, 2015 12:00PM - 12:15PM |
J2.00003: A Study of Aluminum Combustion in Solids, Powders, Foams, Additively-Manufactured Lattices, and Composites James Black, Norman Trammell, Jad Batteh, Nicholas Curran, John Rogers, Donald Littrell This study examines the fireball characteristics, blast parameters, and combustion efficiency of explosively-shocked aluminum-based materials. The materials included structural and non-structural aluminum forms -- such as solid cylinders, foams, additively-manufactured lattices, and powders -- and some polytetrafluoroethylene-aluminum (PTFE-Al) composites. The materials were explosively dispersed in a small blast chamber, and the blast properties and products were measured with pressure transducers, thermocouples, slow and fast ultraviolet/visible spectrometers, and high-speed video. [Preview Abstract] |
Tuesday, June 16, 2015 12:15PM - 12:30PM |
J2.00004: Increasing Combustion Efficiency for Structural Reactive Materials through Design and Processing Tony Zahrah, Rod Rowland, Erin Silva, Donald Littrell This paper describes the development of multifunctional materials -- materials that are both structural and energetic. These materials typically consist of metal-metal, metal-metal oxide, or metal-oxidizer powder blends that are consolidated into structural components via Hot Isostatic Pressing (HIP), and release energy when explosively shocked via anaerobic (intermetallic or thermitic) reactions and aerobic (particle-air) reactions. The mechanical and reactive properties of the materials were tailored through powder selection and ratios. The powder blends included soft and hard materials, and the volume percent from each material was adjusted to control the consolidation temperature. This paper discusses the use of a unique instrumented-HIP technique to minimize the exposure of the powder blend to high temperature and maximize its combustion efficiency. It will focus on the Al-AlMg material system with discussion of its formulation, HIP processing parameters, mechanical properties, and energy release when explosively shocked. [Preview Abstract] |
Tuesday, June 16, 2015 12:30PM - 12:45PM |
J2.00005: Shock Initiated Reactions of Reactive Multiphase Blast Explosives Dennis Wilson, John Granier, Richard Johnson, Donald Littrell This paper describes a new class of reactive multiphase blast explosives (RMBX) and characterization of their blast characteristics. These RMBXs are non-ideal explosive compositions of perfluoropolyether (PFPE), nano aluminum, and a micron-size high-density reactive metal -- Tantalum, Zirconium, or Zinc in mass loadings of 66 to 83 percent. Unlike high explosives, these PFPE-metal compositions release energy via a fast self-oxidized combustion wave (rather than a true self-sustaining detonation) that is shock dependent, and can be overdriven to control energy release rate. The term ``reactive multiphase blast'' refers to the post-dispersion blast behavior: multiphase in that there are a gas phase that imparts pressure and a solid (particulate) phase that imparts momentum; and reactive in that the hot metal particles react with atmospheric oxygen and the explosive gas products to give an extended pressure pulse. The RMBX formulations were tested in two spherical core-shell geometries -- an RMBX shell exploded by a high explosive core, and an RMBX core imploded by a high explosive shell. The fireball and blast characteristics were compared to a C-4 baseline charge. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700