Initiation and propagation of explosion in azides and fulminates

Abstract

An experimental study is made of the initiation and growth of explosion in a series of azides and fulminates. Some organic and inorganic azides which can be melted have been prepared. In the solid state the impact sensitivity of these azides is increased by the presence of a grit particle, provided its melting-point exceeds 500° C. In the liquid state cyanuric triazide can be initiated by the adiabatic compression of a gas bubble, but even in the apparent absence of gas bubbles the molten explosive is very sensitive to impact. An investigation of the growth of the explosion from the point of initiation shows that with the organic azides the reaction can begin as a comparatively gentle burning which accelerates rapidly to detonation. There is evidence that the chemical reaction occurring in the slow stage is different from, and is less complete than, the reaction in the detonation stage. The comparison of a range of azides and of fulminates indicates that the ready pro­pagation of the explosion is associated with the covalent character of the molecule. Increasing the pressure of an inert gas, such as nitrogen, above the explosive has a marked effect in increasing the propagation of the explosion. Confinement has a similar effect, and the results are in agreement with Yoffe’s conclusions from the thermal decomposition of the azides. They suggest that the rapid propagation of the explosion is due to the recombination of excited or atomic nitrogen at or near the surface of the explosive.