NANO ENGINEERED ENERGETIC MATERIALS (NEEM) MURI Overview

Transcription

1 2004 ARMY ENERGETIC MATERIALS MURI AND DURINT REVIEW MEETING Picatinny Arsenal Officers Club October 2004 NANO ENGINEERED ENERGETIC MATERIALS (NEEM) MURI Overview Richard A. Yetter The Pennsylvania State University and the NEEM MURI Team

2 Issues and Motivation Potential benefits of nano energetic materials: More powerful. More reliable. More reproducible. Reduced vulnerability. Safer to handle. Modest gains to date: Controlled rate of energy release. Higher density. Reduced sensitivity. Increased storage lifetime. Multi-functionality. While some performance improvement has been demonstrated, the full extent of the anticipated gains from nanoscale energetic materials has not been realized in large part due to the incompatibility of length scales.

3 Objectives Develop new methodologies to assemble nano-energetic materials that provide concurrent increases in performance and managed energy release rate while reducing sensitivity. Obtain fundamental understanding of the relationship between the design of nanoengineered energetic materials and their reactive and mechanical behaviors.

4 Critical Technology Issues Self-assembly and supramolecular chemistry of the fuel and oxidizer elements of energetic materials have lagged far behind chemistries in other disciplines (e.g., microelectronics, biological systems, and pharmaceuticals). There is no fundamental understanding of what type of supramolecular structures provide desirable performance in combustion, mechanical, and hazard characteristics.

5 Design Possibilities conventionally assembled energetic material with micron-to-millimeter scale energetic structures self-assembled micron-to-millimeter scale energetic structure micron-crystalline oxidizer polymer binder nano-energetic materials nano Al & B nano RDX, HMX, & ADN carbon nanotubes nano-metallic particle self-assembled energetic material with gradient in chemical composition nano-crystalline oxidizer

6 Program Philosophy Bring together leaders in nanotechnology and propellants and explosives Couple multiscale modeling and multiscale diagnostics Research and develop new concepts for assembling and understanding the dynamics of nano engineered energetic materials

7 Participating MURI Team Members David Allara, PSU: chemistry, nanotechnology, self-assembly Ralph Nuzzo, UIUC: chemistry, nanotechnology, self-assembly Dana Dlott, UIUC: chemistry, energetic materials, ultrafast laser spectroscopy Priya Vashishta, USC: physics, materials, atomistic modeling Rajiv Kalia, USC: physics, materials, multiscale modeling Aiichiro Nakano, USC: physics, materials, multiscale modeling Vigor Yang, PSU: engineering, energetic materials, combustion modeling Richard Yetter, PSU: engineering, energetic materials, combustion diagnostics Kenneth Kuo, PSU: engineering, energetic materials, combustion and ballistics

8 Program Elements Synthesis and Assembly Theoretical Analysis and Design Experimental Characterization

9 Program Structure and Interactions Synthesis & Assembly PSU UIUC nano - macro Theoretical Modeling & Simulation USC PSU macro - nano NEEM nano - Experimental Characterization & Diagnostics UIUC PSU macro

10 Synthesis, Self-Assembly, and Supramolecular Chemistry of Nano- Structured Energetic Materials

11 Significant Research Experience on Al Synthesis, Fabrication, and Surface Chemistry Nuzzo UIUC, Allara - PSU SAMs on Al(native oxide)/al Al(metal)-SAM Structures & Interactions Al Vapor Deposition Processes Al Surface Chemistry Materials Characterization

12 Nano Scale Energetic Materials Synthesis and Passivation: Nuzzo-UIUC & Allara-PSU Develop new synthetic methodologies for affecting the low temperature synthesis of highly reactive nanoclusters High surface area aluminum nanoparticles would be ideal high-energy materials A few examples of small aluminum clusters have recently been described (reductive syntheses), but there are no investigations of their use as high energy materials The Al nanoparticles consist of metallic aluminum cores surrounded by a monolayer of a protective shell 10 and 100 aluminum atoms and particle diameters between 0.5 and 1.3 nm H Si H H Stabilized nano-clusters via metal ligand interactions Si 3/2 H 2 Generalize and Expand Synthetic Approaches AlH 3 -TMA Potential route to capped Al nanocluster TMA + 3/2 H 2

13 Nano Scale Energetic Materials Synthesis and Passivation: Nuzzo-UIUC & Allara-PSU AlI + LiN(SiMe 3 ) 2 Al 77 [N(SiMe 3 ) 2 ] Aluminum cluster (far right) consists of nested shells containing (from left to right) 13, 44, and 20 aluminum atoms A. Ecker, E. Weckert, and H. Schnöckel Nature 1997, 387, 379. Generalize and Expand Synthetic Approaches to Aluminum Clusters with Sizes Ranging to 100 nm New SAMs for Cluster Passivation and Size Control Thermal Cluster Growth Ligand-Directed Association Directed Synthesis Full Characterization/Understanding of Structure and Properties at all Length Scales

14 High Energy Content Nanocomposites: Nuzzo-UIUC Novel Growth Chemistries Sub m Teflon particles swollen in solvent, Al nanoparticles grown & passivated in pores, Spherical particles packed to form lattice of passivated nanoparticles Teflon telomer particles Swollen particles Al growth via infusion Encapsulation by vitrification Composites from Aerosol and Particle Spray Deposition Processes, e.g., Nanoparticle Metal/Fluorocarbon Composites Dispersible to ~0.2 µm Particles PFK/PFE Zonyl MP 1100 Thermal Spray Deposition (e.g. TMAA / TiCl 4 / MP 1100)

15 Nano Structured Energetic Materials-Model Systems Nuzzo-UIUC Develop strategies for manipulating the larger mesoscopic organization of high energy nanoscale materials by directed design Fabrication of Energetic Structures Using a Soft Lithographic Patterning Technique Master Spin-Cast PFSOx UVO Sputter Deposit Aluminumx2 Weld Two Aluminum Films Adhesive Contact Decal Transfer Laminate Decal 10µm Decal Release for 3D Integration Bottom layer strong oxidant such as HMX, which is readily deposited in thin film form from the vapor phase

16 Nano Structured Energetic Materials-Model Systems Nuzzo-UIUC Fabrication of Energetic Structures Using Decal Transfer Lithography Si Si Si Photoresist pixel post array m (dia); m (ht) Master Spin coat and cure thin PDMS film. Remove PDMS membrane stencil mask m (thick) Place PDMS membrane on substrate. Evaporate layer through membrane. - Stacked disks of oxidizer, e.g., RDX - Al with 5 mm pitch - Si is a silicon wafer - PDMS is a conformal silicone polymer membrane -capable of achieving submicron resolution in large pattern area Effect depositions for sequential levels. Cap or align second mask for 3D structures Lift-off membrane to reveal pixel array. Cap or align second mask for 3D structures

17 Nano Structured Energetic Materials-Model Systems Allara-PSU Thin film nanostacks [ fuel-(oxidizer-fuel) N - ] (~1-3 nm thick) passivation layer template layer oxidizer layer (SAM) fuel (Al, etc.) Interface/Surface characterization static Capabilities: in-situ (UHV): IR, XPS, ToF-SIMS, AFM ultrasensitive BET for planar-scale surface/pore areas Model structure characterizations: structures, chemical interactions at interfaces T dependence of structures (stability, chem degradation)

18 Shock Precipitation and Supercritical Fluid (SCF) Processing of Nano-sized Oxidizers: Kuo-PSU Two solvent-based methods will be examined in this study Shock precipitation (SP) technique; Supercritical fluid (SCF) technique. A combined SP/SCF processing technique will also be considered. Oxidizer crystals to be considered include: RDX, ADN (ammonium dinitramide), HNF and FOX-7 (1,1-diamino-2,2-dinitroethylene). Two SCF methods will be investigated for application to energetic materials (w/ Victor Stepanov of ARDEC): Rapid Expansion of Supercritical Solutions (RESS). Supercritical Anti-Solvent precipitation (SAS). Rapid mixing via opposed-jet impinging flows will be applied to increase the rate of nucleation and thus reduce the particle size while increasing yield.

19 Theoretical Modeling of Nano-Structured Energetic Materials from the Atomistic/Molecular Scale to the Macroscale

20 Coupled FE/MD/QM Simulations Vashishta, Kalia, Nakano - USC Approach: Finite element (FE) Atomistic molecular dynamics (MD) Quantum-mechanical (QM) calculation based on density functional theory (DFT) Multiscale QM/MD/FE simulation (top) implemented on a Grid (bottom) of supercomputers, data archive, and virtual environment Challenge: Seamlessly couple QM scheme & MD approach based on effective interatomic potentials Collaboratory for Advanced Computing & Simulations (CACS) 1,512 processor Intel Xeon Linux cluster at USC 2.4 million processor-hours of computing on IBM SP4 & Compaq AlphaServer at DoD Major Shared Resources Centers

21 Nano Aluminum Particle Oxidation Vashishta, Kalia, Nakano - USC Number of Atoms: ~ 250,000 Al, ~ 550,000 O; Initial Al cluster 100Å radius Metal Oxide Core-Shell Structure Oxidative Percolation Oxidation Under Closed Conditions Oxide thickness saturates at 40Å after 0.5 ns good agreement with experiment (Nieh et al., Acta mater. 44, 3781 (1996) OAl 4 clusters percolate to form a neutral shield around Al nanoparticle, which impedes oxidation No heat dissipation allows rapid T increase in surface and core. Larger spheres correspond to oxygen and smaller spheres to aluminum; color represents the T.

22 RDX Molecule on Al (111) Surface Vashishta, Kalia, Nakano - USC Quantum mechanical MD simulation in the framework of the density functional theory (DFT)

23 NEEM Behavior in Two-Phase Flow Environments at Meso & Macro Scales : Yang - PSU Couple Relevant Processes at Micro and Meso Length Scales to Macroscale Phenomena Investigate the transport and combustion of nanosized particles in reactive flow environments Establish general analysis accommodating particle & thermo-fluid dynamics for two-phase flow interactions Identify key mechanisms and parameters for maximizing energy release Combustion-Wave Structure of HMXGAP Pseudo- Propellant T sf = ~ 2000 K T dark zone = ~ 1250 K Decomposition, Evaporation, and Gas-Phase Reactions (Bubble) T s = ~ 700 K T melt = 558 K Rapid Consumption of HCN and NO Major Species in Dark Zone: N 2, H 2O, NO, CO, HCN, H CO, N O, H, CO GAP Polymer Residue Secondary Flame Zone Dark Zone Primary Flame Zone (HMX Vapor /Liquid Interface) Foam Layer (HMX Melt Front) Heterogeneous Solid Phase Flame Speed (m/s) = Aerosol Al - Air Flame ~ 1 cm 1.9 cm Analytical prediction Numerical prediction Experimental data Al Particle Diameter (m) HMX GAP

24 Optimization of NEEM Fabrication Techniques based on Supercritical (SCF) Processing: Yang - PSU Numerical Modeling and Optimization of SCF Fabrication Techniques: Rapid expansion of supercritical solution (RESS) Supercritical anti-solvent precipitation (SAS) Shadowgraph images for injection of supercritical methane/ethylene fluid into subcritical environments at various conditions x CH4 =0.1 and d=1.0 mm. Modeling will include: Important near- and super- critical fluid phenomena, including transcritical thermodynamic and transport anomalies Parametric studies will examine effects of flow parameters and hardware design attributes on production of nano-sized materials Outcome will be improvements to existing techniques and new innovative concepts Density gradient field P inj /P c T inj /T c P inj /P chm (C p /C v ) The T inj /T c =1.03 jet has a large jet expansion angle and opaque appearance due to condensation Jet expansion angle differences may come from differences in specific heat ratios and the pressure rise due to the release of latent heat during condensation

25 Experimental Characterization of Reactive and Mechanical Behaviors of Nano-Structured Energetic Materials

26 Time and space resolved spectroscopy of nanoenergetic materials: Dlott - UIUC Approach Picosecond laser flash-heating of nanoenergetic materials (Picosecond CARS, time-resolved emission, streakscope for long distance and directional propagation) Ultrafast (sub ns) microscopy of laser-initiated materials Femtosecond IR laser, time resolved IR spectroscopy (C- H, C-C, Al-O, Al-F, C-F, O-H, etc.) Femtosecond laser-driven shock compression and shock spectroscopy of nanoenergetic materials (pressure 5-10 GPa, material velocity ~0.8 km/s, shock velocity ~4 km/s (40Å/ps), compression factor V = 0.2, rise time 2-3 ps, fall time 15 ps)

27 High repetition rate laser flash-heating (100/s) Dlott-UIUC transparent polymer oxidizer 100 ps oxidizer 100 nm pulse 100 ps heating pulse is matched to metal particle thermal conduction. Particle is uniformly heated, surroundings cold 40 mg sample (3 m thick). Each shot 50 ng (150 m diam) shots per sample 10 cm 1 mm

28 Fast Spectroscopy of Laser Initiated Nanoenergetic Materials: Dlott - UIUC ONO 2 survival fraction Nitrate group consumption in Alex/NC J = 5.9 J/cm 2 abrupt transition when reactions coalsece 0.4 ~300 ps 0.2 conc. indep delay time (ns) 0.2% 0.5% 1.0% 2.0% intensity (arb) Energy release via time-resolved emission 1% in NC 5.6 J/cm J/cm J/cm 2 2ns 0.4 J/cm 2 several ns time (ns) Energy release ~2 ns at low concentration Slows down at higher fluence as reaction propagates over greater distances

29 Surface and Subsurface Analysis of Nano Engineered Energetic Materials: Yetter - PSU In-situ reacting energetic material studies using upright and inverted optical microscopes with high speed photography, micro particle image velocimetry, micro laser induced fluorescence and micro Raman spectrometry In-situ studies of reacting energetic materials using environmental scanning electron microscope at surface and subsurface temperatures of bulk material Examples of Diagnostics Implementation CO 2 Laser Irradiation / Ignition Source/ / Flame Propagation Nd:YAG Laser Beam Expander Microscope Energetic Material Microscope Objective Epi-Fluorecent Prism/Filter Cube CCD Camera CO 2 Laser Irradiation / Ignition Source / Flame Propagation Heating Stage Spectrometer Energetic Material Sample Crucible CCD Camera Microscope Objective ESEM Heated Cell of FEI Quanta 200 SEM for simulating surface processes during reaction ICCD Microscope Epi-Fluorecent Prism/Filter Cube

30 Micro Burner for Combustion Analysis of Nano Composites and Nano Metallic - Metallic Oxidizer Systems: Yetter - PSU Igniter Optical Combustion Chamber Formulate and study the reaction dynamics of nano-composite thermite systems Investigate systems that produce significant gas at high-energy release rates Determine the effect of composition and physical characteristics of the trapped gas, initial temperature, and pressure on regression rates of mixtures High-Speed Camera Thermite Mixture Molten Product Container Pyrometer Optical Combustion Chamber Ignite thermite mixture or pressed pellet to study effect of pressure, initial temperature, trapped gas effect High-speed video records to determine regression rate Pyrometer to measure the surface temperature of the condensed phase products LIF to measure presence of AlO

31 Formulation and Combustion Analysis of New and Advanced Nano-Energetic Materials and Propellants Kuo - PSU Burning Rate Measurements of Newly Processed Propellants Burning Surface Observation of Propellants with Nano-Particles Laser Ignition Characteristics of New propellants with Nanosized Energetic Particles AHE/AME AHE/Nano-RDX Burn Rate AME - RDX/BBA/Alex Nano-RDX/BBA/Alex AHE - HNF/RDX/BBA/AL 1 mm Time [ms]: Propellant burning at 8,000 psi Pressure [psig] Burning Rate Ratio Solid Propellant Strand Burner: capabilities/features Optically accessible Up to 9,500 psi capability Temperature control 60oC < T < 80o

32 Interactions External to MURI TEAM Center for NanoEnergetic Materials ARO DURINT Energetic Materials Design ARO MURI Theoretical Simulation & Modeling Synthesis & Assembly NEEM Experimental Characterization & Diagnostics Industry DoD and DoE Laboratories

33 s of Team Member David Allara, PSU: Ralph Nuzzo, UIUC: Dana Dlott, UIUC: Priya Vashishta, USC: Rajiv Kalia, USC: Aiichiro Nakano, USC: Vigor Yang, PSU: Richard Yetter, PSU: Kenneth Kuo, PSU: