Initiation and detonation in lead azide and silver azide at sub-millimeter geometries

The process by which an energetic material is initiated and transitions from burning to detonation has been investigated and documented in the literature for many different materials. The fast reaction velocities and short reaction lengths of primary explosives have limited the amount of research on the nature of their transient, developing, pre-steady-state detonation processes. The increased interest in micro electro-mechanical systems (MEMS) and the growth of small-scale manufacturing processes has led to the need for a better understanding of the properties of energetic materials at reduced length scales.

This research made use of high-speed streak camera photography to study both the initiation properties and reaction velocities of lead azide and silver azide. The charges studied were cylindrical in shape and had diameters ranging from 200 µm down to 10 ìm. The samples developed for study in these experiments were cylindrical charges of either lead azide, Pb(N3)2, or silver azide, (AgN3), contained in micro-capillaries. A method for the reliable production of charges of both lead azide and silver azide in sub-millimeter geometries has been demonstrated.

Results discussed include reaction velocity, observation of an accelerative reaction, observation of retonation waves, and the reaction of a lead azide charge as small as 10 µm in diameter.