Amorçage en détonation des explosifs hétérogènes de type coulé fondu : Etablissement de corrélations entre microstructure et réactivité

Abstract : This study deals with the detonation initiation by shock of condensed melt-cast high explosives. Solid explosives are heterogeneous materials, made of energetic material grains in a binder, which can be energetic itself. If the existence of hot-spots, preferred initiation sites for chemical reaction at the local scale, is widely recognized, the reaction growth topology, and the microstructure influence, are poorly known for melt-cast explosives. We study here two melt-cast explosive families: hexolites, a mix of hexogen (RDX) grains and trinitrotoluene (TNT) binder, and ontalites made of nitrotriazolone (NTO) and TNT. This study has been focused on the triptyque: characterization - experimentations - modeling.An important work of compilation and re-exploitation of literature data, combined with pure explosives’ equation of state modeling, allowed us to define laws to calculate the explosives’ comportment under a shock solicitation. These ones have been validated, thanks to a mixing method, on different melt-cast and cast-curd plastic bonded explosives. At the same time, the compositions’ microstructure has been also characterized via granulometry measurements and microtomographies, never published for this type of explosive.Plate impact tests have been performed in order to establish the reactive shock trajectory of these compositions, allowing us to determine the relation between the run-distance of detonation and the input pressure. It brought the microstructure influence on hexolite shock sensitivity to light, and gave us some first results for ontalites. The use of continuous and innovative measurements, as microwave interferometry and chirped fiber Bragg gratings, allowed us to study the shock to detonation transition (SDT) with a resolution never seen before. Finally, non-sustained plate impact test have been performed for a validation purpose.A SDT model is proposed. Based on a germination-growth approach of deflagration fronts at the local scale, it takes into account the explosive’s microstructure. This work seems to show the grain fragmentation under shock influence, point we will have to study in the future. Finally, a completion step of reactions, associated with chemical kinetics calculations, has been studied.
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  • HAL Id : tel-01474379, version 1

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Vincent Pierre Chuzeville. Amorçage en détonation des explosifs hétérogènes de type coulé fondu : Etablissement de corrélations entre microstructure et réactivité. Chimie théorique et/ou physique. Université Paris-Saclay, 2016. Français. ⟨NNT : 2016SACLY014⟩. ⟨tel-01474379⟩

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