Electric Spark and ESD Sensitivity of Reactive Solids (primary or secondary explosive, propellant, pyrotechnics). Part II: Energy transfer mechanisms and comprehensive study on E₅₀

Abstract

The energy transfer mechanism from the electric spark to the reactive solid sample in powder form has been determined. Only a small portion of the solid is heated to the explosion critical temperature through a resistive heating by electric current. In fact, hot spots develop at the thinnest part of the solid, i.e. at intergrain contact points. We studied the evolution of thermal diffusivity and of sensitivity to electric spark as a function of powdered HMX granulometry. It allowed us to specify the respective importance of the grain size and shape in this evolution.

New aspects of initiation reactivities of energetic materials demonstrated on nitramines

“…The said effect can be interpreted [43] on the basis of separation of RDX grains from each other by the introduced glass particles (hot spots develop here at the thinnest part of the individual solid under discharge, i.e. at contact micropoints of grains of the identical kinds [44]). An analogous effect of the introduced hot spots in lead azide was found by Stengach [45].…”

The Relationship between Impact Sensitivity of Nitroaromatic Energetic Compounds and their Electrostatic Sensitivity

“…The primary dissociation reactions can be supposed to be identical with the primary splitting processes of low-temperature thermolysis and detonation transformation of molecules of these materials [16]. The electric spark sensitivity of energetic compounds is affected by various parameters, such as the chemical nature of the compound [9], its particle shape and size [10,11], the temperature [12], the moisture content [10], its thermal and impact reactivity [10,[13][14][15], the configuration of the electrodes, and the general structure of the circuit and the discharge time [10]. Although there are various effects that influence the electrostatic sensitivity of energetic compounds, a linear relationship between the test results obtained with various apparatuses can be found [16].…”

“…Reliable estimation of sensitivity parameters of explosives is of utmost importance before their actual synthesis. Several theoretical or empirical methods have been introduced for the estimation of the various sensitivity parameters of nitroaromatic energetic compounds [3][4][5][6][7][8][9][10][11][12][13][14][15][16].…”

Theoretical study of the correlation between electrostatic hazard and electronic structure for some typical primary explosives

“…It is well known that electrostatic charge can be generated when two particles from different materials come into contact and then separate. This is called Btriboelectric charging.^The hazards due to the static charge associated with granular materials, such as dust explosions in pneumatic conveying systems and the ignition of energetic materials by electrostatic discharges, have long been investigated [5][6][7][8][9][10][11][12]. Therefore, the electrostatic spark sensitivity and the static charge accumulation of an explosive are very important parameters when attempting to evaluate the safety of the explosive in an environment in which there can be electrostatic discharges.…”