Experimental Study of Grit Particle Enhancement in Non-Shock Ignition of PBX 9501

The drop weight impact test is the most commonly used configuration for evaluating sensitivity of explosives to non-shock ignition.~ Although developed 60 years ago and widely used both as a material compression test and as a test bed for understanding the ignition process itself, little is known about the flow mechanisms or involvement of grit particles as sensitizing agents.~ In this paper we present the results of a series of experiments designed to study the flow mechanisms and events leading up to ignition.~ The experimental configuration used involves two pellet sizes, 3 and 5 mm in diameter, tested in three conditions, (1) with smooth steel anvils, (2) with standard flint sandpaper, and (3) with shed grit particles loaded between the steel anvils and the pellet faces.~ Diagnostics include optical micrographs, and scanning electron micrographs.~ Un-reacted samples show a variety of morphologies, including what appear to be quenched reaction sites, even at very low drop heights.~ Quasi-static crushing experiments were also done to quantify load-time histories.