Sulfates‐Based Nanothermites: An Expanding Horizon for Metastable Interstitial Composites

Abstract

Metal sulfates (Ba, Bi, Ca, Cu, Mg, Mn, Na, Zn, Zr) were used as oxidizers in reactive compositions with Al nanopowder. These new kinds of nanothermites have outstandingly high reaction heats (4-6 kJ g(-1) ) compared to conventional Al/metal oxides (1.5-4.8 kJ g(-1) ) and also have good combustion velocities (200-840 m s(-1) vs 100-2500 m s(-1) ). These compositions are extremely insensitive to friction making their preparation and handling easy and safe. The sulfate hydration water increases the reaction heats and has a significant effect on the sensitivity to impact and to electrostatic discharge. The reaction of Al with water is easier to initiate than the one with sulfate which leads to two possible decomposition modes for samples exposed to an open flame. The pyrotechnical properties observed with sulfates have also been found for other sulfur oxygenates (SO3 (2-) , S2 O3 (2-) , S2 O8 (2-) ) which opens up new horizons in the domain of metastable interstitial composites.

Highly insensitive and thermostable energetic coordination nanomaterials based on functionalized graphene oxides

“…1 The EMs are still under fast development in terms of new energetic molecules, novel energetic compositions, advanced energetic composites, as well as unique energetic systems. 2 There has been a significant amount of EMs being developed during past decades, including new energetic polymers, 3 novel nitrocompounds, 4 energetic salts, 5 nitrogen rich compounds, based on azole and azine rings, 6 energetic ionic liquids, 7 nanothermites, 8 energetic supermolecules (host/guest complexes, cocrystals) 9 and polynitrogen compounds. 10 However, the newly developed energetic compounds, in most cases, are still not able to completely replace currently used high EMs due to various problems including chemical incompatibility, instability, high sensitivity, and high cost.…”

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

“…Nano-aluminothermic mixtures are thermite compositions, in which aluminum and often the oxidizer are nanopowders. The oxidizer can be a metallic oxide [24,[34][35][36][37], or an oxygenated salt such as: permanganate [38,39], perchlo- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 rate [40,41], periodate [42], sulfate [43], peroxodisulfate [44] or even phosphate [31].…”

“…For nanothermites, this technique should be reserved to the preparation of mixtures which are particularly insensitive to friction or, that contain one component which can be altered in the contact of a liquid. For instance, metallic sulfates can be mixed with aluminum nanopowder by grinding in a mortar [43]. In first place, this procedure is justified by the insensitivity to friction of these energetic compositions.…”

Propellants Reactivity Enhancement with Nanothermites

“…In this article,t he millimeter-sized particles of ac ommercial propellant were coated with an environmentallyf riendly sulfate-basedn anothermite [12],i no rder to improve the ignition and to quickly reach the deflagration regime. Basically,p ropellant grains burn by their surface.T he evolution of the combustion rate along time for an individual propellant grain depends on its composition, shape and size.…”

“…In self-propelled systems, the propellant charge is am onolith whosem ass can sometimes exceed several tons. Accordingt oR eese et al aC uO/Alt hermite made up of micron-sized particles can be used to ignite solid rocket combustors( 0,5 to 50 kg) [11].In this article,t he millimeter-sized particles of ac ommercial propellant were coated with an environmentallyf riendly sulfate-basedn anothermite [12],i no rder to improve the ignition and to quickly reach the deflagration regime. Basically,p ropellant grains burn by their surface.T he evolution of the combustion rate along time for an individual propellant grain depends on its composition, shape and size.…”