Pardubice, Czech Republic
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Kisova P.,University of Pardubice | Svachoucek V.,Svachoucek | Ventura K.,University of Pardubice | Janovsky B.,University of Pardubice | Velehradsky L.,Explosia Inc.
Chemicke Listy | Year: 2011

The study of gun shot residues involves a wide and very interesting problems both from the shooter's viewpoint and from the producer view. Currently, the investigation of gun shot residues is based on the study of morphology and improvement of firm particles and further physical conditions which influence, for instance, their stability in the surveyed environment. Another direction is aimed at the detection of gun shot residues at the shooting place. The toxicity of cartridges of existing and newly developed ammunition classified as non-toxic can be adequately evaluated by a suitably designed method for analysis of gun shot residues.


Benak M.,Slovak University of Technology in Bratislava | Turna M.,Slovak University of Technology in Bratislava | Palcek P.,University of Zilina | Nesvadba P.,Explosia Inc.
Defect and Diffusion Forum | Year: 2010

The aim of the present work was to solve the technology for welding Mg alloy type AZ 63 with aluminium and to assess the quality of the fabricated joints (bimetals-composites). In solving the welding technology, the high affinity of Mg to oxygen has to be considered and therefore as suitable technology either metallurgical joining in vacuum (electron beam etc.) or high-speed solid state welding seem to be feasible. Explosion welding with Semtex S 30 explosive was approved experimentally. Parallel arrangement of welded materials was applied. The more plastic Al material was accelerated. Quality of bonds (bimetals) was assessed by defectoscopy (ultrasound), optical microscopy, microhardness measurement and X-ray microanalysis. It can be generally stated that the basic requirement on joint quality (namely the undulated boundary) was met. The structural composition and absence of inhomogeneities in fabricated bimetals suggest that the desired quality was achieved. © (2010) Trans Tech Publications.


Benak M.,University of Trnava | Turna M.,University of Trnava | Ozvold M.,University of Trnava | Nesvadba P.,Explosia Inc. | And 4 more authors.
METAL 2010 - 19th International Conference on Metallurgy and Materials, Conference Proceedings | Year: 2010

Aluminium -Austenitic CrNi steel bimetal was fabricated by explosion welding with parallel arrangement of welded metals. The formed boundary was studied by using microstructural analysis, microhardness measurement, SEM, EDX and EBSD techniques. Mechanical mixing of materials was observed just after joint formation and after annealing. Degradation of boundary was observed at annealing temperatures of 250°C. Amorphous phase was revealed by EBSD method. © 2010 TANGER Ltd., Ostrava.


Turna M.,University of Trnava | Ondruska J.,University of Trnava | Nesvadba P.,Explosia Inc.
METAL 2010 - 19th International Conference on Metallurgy and Materials, Conference Proceedings | Year: 2010

Development of explosion welding technology for joining DP 600 steel with austenitic steel type X6CrNiMoTi 17-12-2. Weldability of used combined metals was predicted by application of binary and other diagrams. Welding parameters and conditions (vd , vk , vo , ß, h) were determined. Preparation of weld surfaces and set up of welded materials is described. Quality of fabricated bimetals was inspected by ultrasonic defectoscopy, optical microscopy and microhardness measurements. The interface zone of bimetal was in details assessed by EDX analysis. © 2010 TANGER Ltd., Ostrava.


Zeman S.,University of Pardubice | Yan Q.-L.,Tel Aviv University | Gozin M.,Tel Aviv University | Zhao F.-Q.,Xi'an Modern Chemistry Research Institute | Akstein Z.,Explosia Inc.
Thermochimica Acta | Year: 2015

Abstract Mixtures of 1,3,5-trinitroso-1,3,5-triazinane (TMTA) with 1,3,5-trinitro-1,3,5-triazinane (RDX), cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole (BCHMX) and ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), respectively, have been investigated by DSC and TGA techniques. It has been found that there are two endothermic peaks at about 96 °C and 107 °C, due to polymorphic transition and melting of TMTA, whereas only small endothermic peaks were observed in the temperature region of 92.8-95.0 °C for mixtures of RDX-TMTA, BCHMX-TMTA and CL-20-TMTA. These differences in exothermic temperatures of the pristine TMTA versus its mixtures could be a result of co-crystals formation. Moreover, only one complex step for decomposition of TMTA and RDX-TMTA was observed, while at least two steps were found for BCHMX-TMTA and CL-20-TMTA mixtures. TGA measurements showed that a mass loss of TMTA begins at 89.3 °C and has a peak temperature of 185.9 °C. In contrast, the mass loss of RDX-TMTA mixture begins at 142.9 °C and has a peak temperature of 227.6 °C, evidently showing a behavior of a single compound. On the other hand, the activation parameters for the first step decomposition of the BCHMX-TMTA (2.355 J g-1) and CL-20-TMTA mixtures were found to be very close to that of TMTA (1.320 J g-1), strongly indicating that most probably TMTA undergoes decomposes during the first decomposition steps of these mixtures. © 2015 Elsevier B.V.


Zeman S.,University of Pardubice | Ruzicka A.,University of Pardubice | Moncol J.,Slovak University of Technology in Bratislava | Yan Q.-L.,Tel Aviv University | And 2 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2016

The tetrahydrate of the tetrapotassium salt of octahydroimidazo-[4,5-d]imidazol-1,3,4,6-tetrasulfonic acid (TACOS-K), an new energetic material, was investigated in terms of its crystal structure, heat of combustion, thermal stability and decomposition kinetics. Its heat of combustion is −5487 ± 96 J g−1 from which a heat of formation of −3150 kJ mol−1 was estimated. It has been found that this compound has a hexagonal crystal space group with a density of 2.026 g mol−1 at 150 K. The organic anionic skeleton of the TACOS-K molecule is distinctly deformed. Six tetraanions interconnected by coordination to the potassium cations and hydrogen bridges to water molecules form hydrophilic as well as hydrophobic cavities. As an intermediate to synthesize cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole, it decomposes at around 31 °C with a first peak temperature range of 46.6–94.3 °C due to loss of water, depending on the heating rates. Hydrolysis of the N–S bonds might play an important role here. Crystalline water evaporation competes with this hydrolysis. TACOS-K has a residual mass of about 46 % at 2 °C min−1, which increases with the heating rate. Peak of the exothermic process occurs at 235.6 °C at the same heating rate with an enthalpy change of 164 J g−1. Dehydration occurs with an energy barrier of 36.7 kJ mol−1 followed by a shoulder mass loss process with a much higher activation energy 110.6 kJ mol−1, while the activation energy for the main exothermic reaction is about 136.2 kJ mol−1. © 2016 Akadémiai Kiadó, Budapest, Hungary


Trso M.,Slovak University of Technology in Bratislava | Benak M.,Slovak University of Technology in Bratislava | Turna M.,Slovak University of Technology in Bratislava | Nesvadba P.,Explosia Inc.
Defect and Diffusion Forum | Year: 2010

As is well known, the explosion welding is considered for a specific type of cold pressure welding. Welded joints fabricated by this technology show a typical undulated boundary, which characterises both, the welding process and bond quality. This technology allows to weld a relatively wide assortment of combinations of various metals and their alloys [1, 2]. This contribution presents the technological procedure for preparation of composite materials based on three metals (trimetals) by use of industrial explosive Semtex S. It concerns the trimetals as structural carbon steel-Cu-Al and structural carbon steel-Ti-Al. For the anodes and cathodes of electrolysers, used for manufacture of aluminium, mostly bimetals were used up to now, as for example the structural carbon steel - Al. However, the mentioned trimetals exert certain priorities over bimetals, regarding mainly the structural stability at elevated temperatures. This also results in higher reliability at breakdown situations and also in longer life of weldments proper. The mentioned trimetals were prepared at Explosia Inc., Research Institute of Industrial Chemistry Pardubice-Semtín. The bond quality was assessed by optical microscopy, microhardness measurement across the bond boundary and also by X-ray microanalysis. © (2010) Trans Tech Publications.


Pelikan V.,University of Pardubice | Zeman S.,University of Pardubice | Yan Q.L.,University of Pardubice | Erben M.,University of Pardubice | And 2 more authors.
Central European Journal of Energetic Materials | Year: 2014

Two types of plastic bonded explosives (PBXs) based on ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (ε-HNIW, CL-20), and PBXs based on 1,3,5-trinitro-1,3,5-triazinane (RDX), ß-1,3,4,7-tetranitro-1,3,5,7-tetrazocane (ß-HMX) and cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole (bicyclo-HMX, BCHMX) were prepared using a polyisobutylene binder with dioctylsebacate (DOS) as plasticizer, i.e. a C4 matrix. One version of the e-HNIW PBX is a product with reduced sensitivity (RS-ε-HNIW). All these PBXs, referenced respectively as RS-ε-HNIW-C4, ε-HNIW-C4, RDX-C4, HMX-C4 and BCHMX-C4, were tested using the Small Scale Gap Test according to STANAG 4488. The results of the gap test on the PBXs with RDX, ß-HMX and BCHMX correspond to the impact sensitivities of the original crystalline nitramines. This is not entirely valid for e-HNIW. In other words, PBXs with RS-ε-HNIW cannot achieve as low a shock sensitivity as would be expected from the differences obtained from the impact sensitivities between RDX, ß-HMX and BCHMX, on the one hand, and RS-e-HNIW on the other. It is shown that the morphological stability of RS-ε-HNIW in the C4 matrix is insufficient. However, further development and use of RS-ε-HNIW as a filler of PBXs would seem to be both desirable and beneficial. Despite the relatively high impact sensitivity of crystalline BCHMX, the shock sensitivity of its analogous C4 PBX is already good, and comparable with that of RS-ε-HNIW.


Yan Q.-L.,University of Pardubice | Zeman S.,University of Pardubice | Elbeih A.,Military Technical College | Zbynek A.,Explosia Inc.
Central European Journal of Energetic Materials | Year: 2013

The thermal behavior and decomposition kinetics of Semtex 10 polymeric matrix (Semtex) bonded PBXs containing RDX (1,3,5-trinitro 1,3,5-triazinane), HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane), BCHMX (cis-1,3,4,6- tetranitrooctahydroimidazo [4,5-d] imidazole), HNIW (2,4,6,8,10,12-hexanitro- 2,4,6,8,10,12-hexaazaisowurtzitane) have been investigated by means of nonisothermal TG and DSC techniques. It is shown that only a single decomposition process occurs for RDX-SE and HMX-SE whilst an obvious two-step process occurs for CL-20-SE and BCHMX-SE. The onset of the exotherms were observed at 210.6, 239.7, 279.2 and 229.4 °C with the peak maxima at 232.2, 249.4, 280.4 and 240.2 °C, and energy changes of 1808, 2140, 612 and 1757 J·g-1 for RDX-SE, BCHMX-SE, HMX-SE and CL-20-SE, respectively. It has been found that the Semtex matrix has little influence on the activation energy distribution for RDX, BCHMX and e-CL-20. The activation energies for BCHMX-SE and CL-20-SE decomposition are almost independent of the degree of conversion, with mean values of 159.6 ±1.9 and 187.3 ±1.8 kJ·mol-1. It has been proved that Semtex and Viton A are better binders than C4 and Formex for ε-CL-20 and RDX based PBXs in terms of their greater thermal stability, and Formex is a poor binder for BCHMX.


Elbeih A.,University of Pardubice | Jungova M.,University of Pardubice | Zeman S.,University of Pardubice | Vavra P.,University of Pardubice | Akstein Z.,Explosia Inc.
Propellants, Explosives, Pyrotechnics | Year: 2012

Plastic explosives based on different cyclic nitramines with different polymeric matrices were prepared and studied. The used polymeric matrices were fabricated on the basis of polyisobutylene (PIB), acrylonitrile-butadiene rubber (ABR), Viton A, and polydimethyl-siloxane as binders, whereas the nitramines named RDX (1,3,5-trinitroperhydro-1,3,5-triazine), β-HMX (β-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), BCHMX (cis-1,3,4,6- tetranitrooctahydroimidazo-[4,5-d]imidazole) and ε-HNIW (ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) were used as explosive fillers. Commercial Semtex 10, based on pentaerythritol tetranitrate (PETN), was used for comparison. Impact sensitivity, loading density, ρ, detonation velocity, D, and relative explosive strength (RS) measured by ballistic mortar were determined. It was concluded that plastic BCHMX based on Viton A or PIB-matrix exhibits higher RS compared with PBXs based on RDX and HMX. Correlations between RS and the impact sensitivity, the ρD 2 term and the square of the detonation velocity were studied and discussed. The results confirm the well-known fact that increasing the performance is usually accompanied by an increase in the sensitivity of the explosives. In this connection, Viton A enables achieving a high RS, but with a relatively high sensitivity of the PBXs, whereas the polydimethyl-siloxane matrix should perhaps give PBXs with optimum explosive strength and sensitivity parameters. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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