Phase stability of {epsilon} and {gamma} HNIW (CL-20) at high-pressure and temperature

Journal Article · Wed Dec 12 04:00:00 EST 2007 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2832955· OSTI ID:21039532

Gump, Jared C; Stoltz, Chad A; Peiris, Suhithi M ^[1]

---

1. Indian Head Division-Naval Surface Warfare Center, Indian Head, MD 20640 (United States)

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 ({alpha}, {beta}, {gamma}, {epsilon}, {zeta}). 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 deg. 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 deg. C then underwent a transition to the gamma phase above 125 deg. C and then thermal decomposition occurred above 150 deg. C. Upon compression, the gamma phase underwent a phase transition at both ambient temperature and 140 deg. C. Pressure--volume data for the epsilon and gamma phase at ambient temperature and the epsilon phase at 75 deg. C were fit to the Birch-Murnaghan formalism to obtain isothermal equations of state.

• OSTI ID: 21039532
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 955; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMBIENT TEMPERATURE
COMPRESSION
COMPUTERIZED SIMULATION
DIAMONDS
EQUATIONS OF STATE
EVALUATION
FOURIER TRANSFORMATION
INFRARED SPECTRA
ORGANIC COMPOUNDS
PERFORMANCE
PHASE DIAGRAMS
PHASE STABILITY
PHASE TRANSFORMATIONS
PRESSURE RANGE GIGA PA
PYROLYSIS
THERMODYNAMIC PROPERTIES
X-RAY DIFFRACTION