Sieve stack and laser diffraction particle size analysis of IMX-104 low-order detonation particles

Sieve stack and laser diffraction particle size analysis of IMX-104 low-order detonation particles Bigl, Matthew F.; Beal, Samuel A.; Walsh, Michael R.; Ramsey, Charles A.; Burch, Katrina M. When an artillery round undergoes a low-order detonation during live-fire training or an unexploded ordnance clearance operation, up to 25% of the round’s energetic contents are scattered over a small, localized area, some-times less than 100 m². Training-range fate and transport models require an accurate representation of the particle-size characteristics of the material left behind from low-order detonations. This study investigated using laser diffraction particle size analysis to characterize 26 samples collected from four low-order command-detonated 81 mm mortar bodies filled with IMX-104. The refractive index of IMX-104 was estimated using an iterative recalculation technique on a Horiba LA-960 that yielded 1.845 0.01𝘪. Of the 25 triplicate analyses conducted using this value, 12 passed the USP measurement standard with 9 of the remaining samples found to have had a reduction in particle size during analysis that caused artificially high coefficient of variance values. The cumulative percent of particle sizes determined by laser diffraction and sieve stack differed by 0%–21.9% (median = 0.2%–7.2%). In ad-dition, the higher resolution results of the laser diffraction particle size analysis, especially for particles smaller than 0.5 mm, make it the preferred method of analysis. Technical Report