Abstract
The detonation of carbon-rich high explosives yields solid carbon as a major constituent of the product mixture, and depending on the thermodynamic conditions behind the shock front, a variety of carbon allotropes and morphologies may form and evolve. We applied time-resolved small-angle X-ray scattering (TR-SAXS) to investigate the dynamics of carbon clustering during detonation of PBX 9502, an explosive composed of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and 5 wt % fluoropolymer binder. Solid carbon formation was probed from 0.1 to 2.0 μs behind the detonation front and revealed rapid carbon cluster growth which reached a maximum after ∼200 ns. The late-time carbon clusters had a radius of gyration of 3.3 nm which is consistent with 8.4 nm diameter spherical particles and matched particle sizes of recovered products. Simulations using a clustering kinetics model were found to be in good agreement with the experimental measurements of cluster growth when invoking a freeze-out temperature, and temporal shift associated with the initial precipitation of solid carbon. Product densities from reactive flow models were compared to the electron density contrast obtained from TR-SAXS, and used to approximate the carbon cluster composition as a mixture of 20% highly ordered (diamond-like) and 80% disordered carbon forms, which will inform future product equation of state models for solid carbon in PBX 9502 detonation product mixtures.
| Original language | English |
|---|---|
| Pages (from-to) | 23129-23140 |
| Number of pages | 12 |
| Journal | Journal of Physical Chemistry C |
| Volume | 121 |
| Issue number | 41 |
| DOIs | |
| State | Published - Oct 19 2017 |
| Externally published | Yes |
Funding
The authors acknowledge support from DOE-NNSA and the Dynamic Material Properties program. This publication is based upon work performed at the Dynamic Compression Sector supported by the Department of Energy, National Nuclear Security Administration, under Award Number DE-NA0002442 and operated by Washington State University. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Prepared by LLNL under Contract DE-AC52-07NA27344. This work was performed, in part, at the Center for Integrated Nanotechnologies (CINT). CINT is funded by the DOE Office of Basic Energy Sciences. We are grateful to Joshua Coe (LANL) and Joshua Hammons (LLNL) for helpful discussions and feedback.