In-situ monitoring of flow-permeable surface area of high explosive powder using small sample masses

Journal Article · Tue Feb 17 00:00:00 EST 2015 · Propellants, Explosives, Pyrotechnics

DOI:https://doi.org/10.1002/prep.201400289· OSTI ID:1266674

Maiti, Amitesh ^[1]; Han, Yong ^[1]; Zaka, Fowzia ^[1]; Gee, Richard H. ^[1]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

To ensure good performance of high explosive devices over long periods of time, initiating powders need to maintain their specific surface area within allowed margins during the entire duration of deployment. A common diagnostic used in this context is the Fisher sub-sieve surface area (FSSA). Furthermore, commercial permeametry instruments measuring the FSSA requires the utilization of a sample mass equal to the crystal density of the sample material, an amount that is often one or two orders of magnitude larger than the typical masses found in standard detonator applications. Here we develop a customization of the standard device that can utilize just tens of milligram samples, and with simple calibration yield FSSA values at ac curacy levels comparable to the standard apparatus. This necessitated a newly designed sample holder, made from a material of low coefficient of thermal expansion, which is conveniently transferred between an aging chamber and a re-designed permeametry tube. This improves the fidelity of accelerated aging studies by allowing measurement on the same physical sample at various time - instants during the aging process, and by obviating the need for a potentially FSSA-altering powder re-compaction step. We used the customized apparatus to monitor the FSSA evolution of a number of undoped and homolog-doped PETN powder samples that were subjected to artificial aging for several months at elevated temperatures. These results, in conjunction with an Arrhenius-based aging model were used to assess powder-coarsening - rates under long-term storage.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1266674
• Alternate ID(s): OSTI ID: 1786621
• Report Number(s): LLNL-JRNL-663729
• Journal Information: Propellants, Explosives, Pyrotechnics, Vol. 40, Issue 3; ISSN 0721-3115
• Publisher: Wiley
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
specific surface area
flow permeametry
powder coarsening