This article reports on a new family of detonating compositions in which ammonium dinitramide (ADN) is used as an explosive oxidizer, and red phosphorus (P r ) or titanium hydride (TiH 2 ) as fuels. At optimized ADN/fuel ratios, these compositions have typical explosion heats higher than 7 kJ/g, detonation velocities in 3 mm diameter tubes ranging from 1.2 to 2.0 km/s at~40 % of their theoretical maximum density, with a run to detonation distance between 20 and 40 mm. Both compositions are insensitive to electrostatic discharge, but are very sensitive to impact and friction, ADN/P r mixtures being the most sensitive to these stress. The shockwave released by the reaction of these materials, efficiently initiates the detonation of high explosives such as pentaerythritol tetranitrate (PETN) or hexogen (RDX). In view of these characteristics, ADN-based detonating compositions must be considered as "green" substitutes for primary explosives containing heavy metals.
Submicron-sized powders of silver azide (AgN 3 ) were prepared by Curtius' reaction between silver nitrate (AgNO 3 ) and sodium azide (NaN 3 ) in aqueous solutions by a new process: the Spray Flash Synthesis (SFS). The SFS process consists in spraying the two precursor solutions in a heated atomization chamber (130-190 °C), maintained under low vacuum (15-30 kPa). The reaction occurs in the droplets which have collided; the final size of particles is limited by the fast evaporation of water and the small amount of matter available in each droplet which can be considered as an individual micro-reactor.The mean particle sizes of silver azide synthesized by the SFS process range from 220 nm to 390 nm, which means that these particles are three times smaller than those obtained by the conventional precipitation method. Submicron-sized AgN 3 powders can be initiated by a photographic flash.
The pyrotechnic compositions made up of potassium perchlorate (KClO 4 ) and titanium hydride (TiH 2 ), known as THKP, have a fast deflagration velocity (~500 m/s), along with low sensitivity and high stability. In this research, a new kind of THKP was formulated from a submicron powder of KClO 4 (50-400 nm) prepared by the Spray Flash-Evaporation (SFE) process. The use of fine KClO 4 not only ensures better oxidation of TiH 2 , but also leads to a transition to detonation in the THKP. This transition is observed in loose powders placed in small diameter tubes (3 mm). The distance of transition is relatively short (17-22 mm) and increases with the KClO 4 content of the THKP mixture. The detonation front propagates steadily, at a velocity of~1250 m/s in THKP powders with 86 % of porosity. The shockwave velocity varies little with the perchlorate content in the domain of composition studied (55-74 wt.% of KClO 4 ). Conversely, in the classical THKP mixtures prepared from micron-sized KClO 4 and tested in the same conditions, no transition to detonation is observed; the combustion slows down and eventually stops. Finally, owing to their high sensitivity thresholds to impact (S Imp. � 44.7 J), friction (S Fr. � 192 N), and electrostatic discharge (S ESD � 34.7 mJ), THKP mixtures prepared from submicron KClO 4 can be classified as low-sensitivity primary explosives.
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