Search

Hexanitrostilbene (HNS) is an energetic ingredient that is widely used in commercial and military explosives for its thermal stability. However, characterization of its thermodynamic parameters and phase stability is lacking. Crystalline properties, such as bulk modulus and thermal expansion, are necessary to accurately predict the behavior of shocked solids using hydrodynamic codes. In order to obtain these values, equations of state of fine-particle (type IV) HNS were investigated using synchrotron angle-dispersive x-ray diffraction experiments at static high-pressure and temperature. The samples were compressed and heated using diamond anvil cells. Pressure - volume data for HNS at ambient temperature were fit to the Birch-Murnaghan and Vinet formalisms to obtain bulk modulus and its first pressure derivative. Temperature - volume data at ambient pressure were fit to obtain the volume thermal expansion coefficient. [ABSTRACT FROM AUTHOR]

2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) is an energetic ingredient that has an impact sensitivity close to that of TATB, yet a calculated energy content close to HMX. Reported tests of formulated LLM-105 reveal that it is a good candidate for a new insensitive high-performance explosive. As use of LLM-105 increases, thermodynamic parameters and phase stability will need to be determined for accurate modeling. In order to accomplish this goal, isothermal equations of state of LLM-105 at static high-pressure and temperature were investigated using synchrotron angle-dispersive x-ray diffraction experiments. The samples were compressed and heated using diamond anvil cells. Pressure—volume data for LLM-105 at ambient temperature and 100° C were fit to the Birch-Murnaghan formalism to obtain isothermal equations of state. Temperature—volume data at ambient pressure were fit to obtain the volume thermal expansion coefficient. [ABSTRACT FROM AUTHOR]

Hexanitrohexaazaisowurtzitane (CL-20) is one of the few ingredients developed since World War II to be considered for transition to military use. Five polymorphs have been identified for CL-20 by FTIR measurements (α, β, γ, [variant_greek_epsilon], ζ). As CL-20 is transitioned into munitions it will become necessary to predict its response under conditions of detonation, for performance evaluation. Such predictive modeling requires a phase diagram and basic thermodynamic properties of the various phases at high pressure and temperature. Therefore, the epsilon and gamma phases of CL-20 at static high-pressure and temperature were investigated using synchrotron angle-dispersive x-ray diffraction experiments. The samples were compressed and heated using diamond anvil cells (DAC). Pressures and temperatures achieved were around 5 GPa and 240 °C, respectively. The epsilon phase was stable to 6.3 GPa at ambient temperature. When heated at ambient pressure the epsilon phase was sustained to a temperature of 120 °C then underwent a transition to the gamma phase above 125 °C and then thermal decomposition occurred above 150 °C. Upon compression, the gamma phase underwent a phase transition at both ambient temperature and 140 °C. Pressure—volume data for the epsilon and gamma phase at ambient temperature and the epsilon phase at 75 °C were fit to the Birch-Murnaghan formalism to obtain isothermal equations of state. [ABSTRACT FROM AUTHOR]

Explosive formulations with reduced-sensitivity RDX showed reduced shock sensitivity using Naval Ordnance Laboratory (NOL) Large Scale Gap Test, compared with similar formulations using standard RDX. Molecular processes responsible for the reduction of sensitivity are unknown and are crucial for formulation development. Vibrational spectroscopy at static high pressure may shed light on the mechanisms responsible for the reduced shock sensitivity as shown by the NOL Large Scale Gap Test. I-RDX®, a form of reduced- sensitivity RDX was subjected to static compression at ambient temperature in a Merrill-Bassett sapphire cell from ambient to about 6 GPa. The spectroscopic techniques used were Raman and Fourier-Transform IR (FTIR). The pressure dependence of the Raman mode frequencies of I-RDX® was determined and compared with that of standard RDX. The behavior of I-RDX® near the pressure at which standard RDX, at ambient temperature, undergoes a phase transition from the α to the γ polymorph is presented. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Reactions and kinetics of the new less-sensitive form of RDX developed by Eurenco (known as I-RDX®) need to be compared to standard RDX, especially at shock pressures and temperatures. To evaluate the effect of pressure samples of I-RDX® and standard RDX were compressed to various static pressures in anvil cells. To evaluate the effect of temperature samples were initiated with different fluences of a 5ns pulsed Nd:YAG laser. As a measure of global reaction rate, changes in transmittance through the samples were monitored during reaction. Both RDX and I-RDX® were initially transparent under pressure, becoming opaque soon after initiation and then clear as the final gaseous products are formed. A comparison of the global reaction times obtained under various pressure and fluence conditions for I-RDX® and RDX samples are presented. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The detonation and subsequent combustion of aluminized explosive formulations depend heavily on the oxidation reactions of aluminum. Fuel-rich formulations require oxygen from an external source (nominally an oxygen-containing atmosphere or detonation products) to burn the fuel to completion. Dynamic spectroscopic measurements are made for an aluminized explosive (PBXIH-135) to investigate the effect of changing atmospheres on the combustion properties of aluminum. The explosive formulation is tested under normal atmospheric conditions and in an atmosphere of nitrogen. Light emission (from 350–550 nm) from the explosive event is collected in a spectrometer and dispersed temporally in a streak camera. Aluminum emission (centered at 396 nm) is commonly observed in each atmosphere although the emission persists longer in nitrogen. Aluminum nitride (AlN) is observed as an intermediate in the oxidation of aluminum when oxygen is removed from the atmosphere. New, nitrogen-containing species (near 387 and 418 nm) also arise in the nitrogen atmosphere experiments. A slower, less intense aluminum monoxide (AlO) emission observed in the nitrogen atmosphere may correspond to the slower oxidation reactions of aluminum and detonation products (CO2 and H2O). The peak assignments and global kinetics of each species are presented and the implications of these results on atmospheric effects are discussed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]