Nanothermites: A short Review. Factsheet for Experimenters, Present and Future Challenges

Hum Factors Mech Eng Def Saf

Martin

Schnell

et al. 2019

Self Cite

The integration of nanostructured materials in defense systems is expected to improve their performance in terms of power, safety, and reliability. That is why considerable research effort has been undertaken by major military powers worldwide in this domain. The first important step was to develop the production capacities of organic explosives in the state of fine powders with submicron to nanosized particle size distributions. The Spray Flash Evaporation (SFE) process, which is a unique method for producing such materials, was developed at industrial scale. Explosive nanopowders obtained by this process were subsequently mixed with nanosized pyrotechnic compositions such as nanothermites, to prepare hybrid detonating materials able to replace lead-based primary explosives. Composite propellants can also be prepared by SFE which allows mixing their components in a single step with better homogeneity. The ultimate challenge is to move from powder to object, in order to integrate energetic nanomaterials in operational systems. Although the research in this last domain is still in its infancy, several ways of preparation of objects from nanothermites have been recently reported in scientific literature. The focus will be on two examples studied in our laboratory. The first one is the preparation of nanothermites in the state of solid, porous foams; the second one is the use of nanothermites for coating grains of propulsive powder to change their combustion properties.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Energetic Nanoparticles and Nanomaterials for Future Defense Applications

Hum Factors Mech Eng Def Saf

Martin

Schnell

et al. 2019

Self Cite

“…In this experiment, the detonation front propagates through an ADN charge with a diameter of only 3 mm, at a steady velocity of 1920 m/s. The detonation is initiated by the reaction of an Al/CuO nanothermite, which is a fast-burning, albeit not-detonating energetic composition [14][15][16]. The detonation of ADN is probably activated by the shock wave produced by the reaction of the nanothermite on liquid ADN, which is first formed by the convective preheating of ADN nanopowder by the combustion of the nanothermite.…”

Section: Detonation Tests With Adnmentioning

confidence: 99%

Hazardous Properties of Molten Ammonium Dinitramide

Propellants Explo Pyrotec

Schwartz

Oudot

et al. 2020

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The purpose of this article is to alert our peers on the danger faced by those who carry out experiments involving molten ammonium dinitramide (ADN). In recent experiments aiming at preparing submicron particles of this compound, a preliminary study of the sensitivity to impact of molten ADN was performed. These first tests have shown that the sensitivity threshold of molten ADN to impact is more than one order of magnitude lower that the one on solid ADN (< 0.25 J vs. 4 J) and similar to the one of nitroglycerin (< 0.25 J), making liquid ADN extremely hazardous to handle. Detonation tests, which were performed in strong steel sheaths open to one end, have shown that the initiation of the detonation and its subsequent propagation occur both in solid and liquid ADN charges, having a diameter of only 4 mm. The critical diameter of solid ADN which is between 25 and 40 mm according to literature, is therefore decreased by at least an order of magnitude when ADN is placed in strong metallic confinement. On the other hand, the detonation of liquid ADN produces stronger destructive effects than the detonation of solid ADN, meaning that the detonation mechanisms of this explosive are different in its two physical states. In conclusion, liquid ADN must be considered in practice as a more hazardous and powerful explosive than solid ADN. This raises the issue of all experiments in which ADN is likely to be formed in molten state.

“…A developing approach consists in preparing hybrid detonating compositions by mixing a nanothermite, with a secondary explosive in submicron-sized powder [2]. These compositions which are called nanostructured thermites and explosives (NSTEX) are the missing link between pyrotechnics and explosives [3]. Nanothermites, which are the pyrotechnic component of NSTEX, consist of aluminium nanopowder mixed with metallic oxides or sulphates [4,5].…”

Section: Introductionmentioning

confidence: 99%

New Detonating Compositions from Ammonium Dinitramide

Propellants Explo Pyrotec

Schwartz

Schnell

et al. 2021

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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.