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  • Sheridan et al studied and patented a

    2018-10-22

    Sheridan et al. studied and patented a thermobaric munition including a composite explosive material, the composite explosive material having a high explosive composition anda detonable energetic material dispersed within the high-explosive composition [55]. The detonable energetic materials investigated were in the form of a thin film, the thin film having at least one layer composed at least in part by a reducing metal and at least one layer composed at least in part by a metal oxide. The work included tailoring the blast characteristics of high explosive composition to match a predetermined time-pressure impulse. Anderson et al. considered the detonation properties of combined-effects explosives [56]. In the development of new explosives, it is quite often necessary to balance a number of factors contributing to performance while certain formulation constraints exist. In that sense, statistical design of experiments (DOE) is a valuable tool for rapid formulation optimization and minimization of hazardous and costly testings. During the development of metal-loaded explosives, designed for the enhanced blast, it was discovered that upon proper formulation, aluminum additives gave full reaction accompanied by volume expansions, which resulted in extremely high Gurney energies equivalent to explosives LX-14 and PBXN-5 but with lower loading of nitramines. The early aluminum oxidation can be described by eigenvalue type detonations, where the fully reacted Hugoniot of the condensed phase aluminum oxide and explosive products lies below the unreacted aluminum Hugoniot. Such an analysis describes fully the agreement of aluminum consumption and volume expansions from 1-in. copper cylinder expansion tests and an analytic cylinder model, as well as detonation calorimetry with the early reaction of aluminum that also causes a shift in the gaseous reaction products to higher enthalpy species, such as CO and H2, thus leading to further improvement in the direction of augmentation of blast. Hence, both the mechanical protein phosphatase inhibitor (for fragmentation or “metal-pushing”) and blast (for structural targets) are available in a single explosive fill. Note that this provides capability for combined metal-pushing and blast in a single explosive that was not previously possible [56]. Multi-walled active explosive charges (especially the hollow charges that contain hollow chambers within the explosives) contain metal carbonyls, either as pure substances or granules, that are mixed with the inorganic fuels and are integrated within the closed container of the explosive charge. Zimmermann patented some suitable metal carbonyls, which are considered as non-directional blast enhancers. They consist of Cr(CO)6, W(CO)6, Mo(CO)6, Fe(CO)5, Fe2(CO)9, and Fe3(CO)12[34]. It was claimed that the charges having those carbonyls can be used for guided or unguided munitions or for gun ammunition. It has to be mentioned that the search for novel and adaptive energetic materials requires innovative combinations between the particle technology and nanotechnology [57]. Nowadays nanomaterials are the focus of increased interest, since they possess some properties which highly differ from their macroscopic counterparts. Many applications recently take the advantage of possession of the new functionalities and manufactured nanoparticles [57]. In the recent years more attention has been paid not only to amelioration of the microstructure of the energetic materials but also to the search of possible modifications of materials that can be achieved by the application of proper coatings [58,59]. Parallel to these developments, the research on energetic nanomaterials is getting more and more attention. Beside the synthesis of energetic nanomaterials, another area of interest is the coating of energetic (nano)powders, in order to be able to modify their properties or to add new functionalities to these particles. Modified energetic materials find various applications in explosives, such as rocket and gun propellants, and pyrotechnic devices, etc. The modified energetic materials are expected to yield enhanced properties, e.g., enhanced blast, a lower vulnerability toward shock initiation, enhanced shelf-life and environmentally friendly replacements of the currently used materials. An experimental setup for coating of the existing powders was designed and constructed [57]. The experimental technique is based on a special plasma application which, contrary to more general plasmas, can be operated at relatively low temperatures and ambient pressure. This allows the handling of heat-sensitive materials, otherwise they would readily decompose or react at higher temperatures. The facility used for the coating of energetic powders in the lower micron range is based on a fluidized bed reactor in which the powder circulates. In this paper, an experimental technique was described in which CuO powders that were coated with a very thin, nanoscale deposit of a SiO-containing layer were tested first [57].