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The possibility of using the method of flameless combustion of RDX in ballasted systems to produce composite materials containing copper and zinc particles has been studied. RDX was used as the initial energetic material, hexamethylene diisocyanate as the binder, copper hydroxocarbonate and copper oxalate were used as precursors. Highly porous composite materials containing nanosized particles of copper, zinc oxide or their mixtures were obtained by optimizing the flameless combustion conditions. [ABSTRACT FROM AUTHOR]

It has been shown experimentally that the flameless combustion of RDX mixtures with iron precursors, nitrogen-containing additives, and a polymer binder can lead to the formation of iron nitrides. Nanosized particles of iron nitride (Fe3N) were obtained by optimizing the ratio of initial components and the conditions of flameless combustion of RDX. The method developed for obtaining iron nitrides in this way can be used to obtain nanosized particles of nitrides of other elements. [ABSTRACT FROM AUTHOR]

Technologically viable principles have been developed for the preparation of titanium and zirconium powders via reduction of metal oxides. We have studied the effect of synthesis conditions (starting-mixture composition and relationships between reactants) on the composition, structure, and particle size of the powders. The results demonstrate that the addition of excess magnesium to the starting mixture leads to the complete reduction of the oxides and that reducing the combustion temperature of the starting mixture leads to an increase in the percentage of zirconium oxide in the final product. The titanium and zirconium powders prepared in the combustion regime with a reduction stage consist of agglomerates of particles ranging widely in size: from large (several microns) to ultrafine and nanoscale particles. The use of magnesium perchlorate as a heating additive leads to the formation of a titanium–zirconium solid solution. The composition of the powders has been determined by chemical analysis, microstructural analysis, and X-ray diffraction. [ABSTRACT FROM AUTHOR]

The combustion of cellulose nitrate in ballasted mixtures containing an organic binder and nickel hydroxycarbonate or silver carbonate as precursors resulted Ni or Ag nanoparticles. The formation of Ni and Ag nanoparticles from flameless combustion of cellulose nitrate was monitored by time-resolved X-ray diffraction. During the formation of the Ag nanoparticles, the diffraction patterns exhibited only signals from decreasing amounts of the precursor and newly simultaneously formed 20-30 nm silver particles. It was detected that in the systems with Ni precursor the formation of the Ni 5-10 nm crystals proceeded by some 2-3 s diffraction-silent intermediate states of the whole system. [ABSTRACT FROM AUTHOR]

The effect of the content of combustible particles on the spatial forms of the combustion wave in a gasless thermite-inert material model system is studied. It is shown that the lower flammability concentration limit for this mixture is related to the formation of a three-dimensional binding percolation cluster or to a percolation phase transition. Near the lower concentration limit, the combustion of model mixtures enters a smoldering regime in which separate combustion sources move randomly in the volume of the unburned material. If the initial composition contains more than 47% thermite particles, a motionless heated surface forms, along which separate incandescent combustion sources move. The motion of this surface in the unburned material occurs only locally as a result of motion of the combustion sources on it. The formation of this unified heated surface corresponds to the occurrence of a second percolation phase transition. When the volumetric content of thermite particles in the initial mixture is higher than 70%, separate combustion sources merge into a unified surface of layer-by-layer combustion due to the occurrence of a third percolation phase transition. [ABSTRACT FROM AUTHOR]