Showing papers in "Central European Journal of Energetic Materials in 2016"
TL;DR: In this paper, the thermal behavior and decomposition kinetics of trinitrohexahydrotriazine (RDX) and its polymer bonded explosive (PBX) containing a hydroxyl-terminated polybutadiene (HTPB) based polyurethane binder in the ratio 80% RDX/20% HTPB were investigated using various experimental techniques and analytical methods.
Abstract: In this paper, the thermal behavior and decomposition kinetics of trinitrohexahydrotriazine (RDX) and its polymer bonded explosive (PBX) containing a hydroxyl-terminated polybutadiene (HTPB) based polyurethane binder in the ratio 80% RDX/ 20% HTPB were investigated using various experimental techniques and analytical methods. The HTPB polyurethane matrix contains other additives and was cured using hexamethylene diisocyanate (HMDI). Thermogravimetric analysis (TGA), Differential Scanning Calorimetry (DSC), Vacuum Stability Test (VST) and Ignition Delay Techniques were applied both isothermally and non-isothermally. The kinetic parameters were determined using both the isoconversional (model free) and the model-fitting methods. For comparison, Advanced Kinetics and Technology Solution (AKTS) software was also used. It was found that the addition of an HTPB-based polyurethane matrix to pure RDX decreased its decomposition temperature. It was also found that RDX/ HTPB has a lower activation energy than pure RDX. The polyurethane matrix had a significant effect on the decomposition mechanism of RDX resulting in different reaction models. It was concluded that the activation energies obtained using the Ozawa, Flynn, and Wall (OFW) and Kissinger-Akahira-Sunose (KAS) methods were very close to the results obtained via the AKTS software lying in the range 218.3-220.2 kJ·mol−1. The VST technique yielded kinetic parameters close to those obtained using TG/DTG. On the other hand, the Ignition Delay Technique yielded different and inconsistent kinetic parameters.
66 citations
TL;DR: A review of the available literature on the properties of 1,1-diamino-2,2dinitroethene and formulations containing FOX-7 is presented in this article.
Abstract: A review of the available literature on the properties of 1,1-diamino-2,2dinitroethene (DADNE, FOX-7) and formulations containing FOX-7 is presented in this paper. The structural, thermal and spectroscopic properties as well as the sensitivity and explosive properties of FOX-7 are described. Compositions containing FOX-7 are characterized in details and their sensitivity and explosive properties are presented. Potential areas of application for such formulations have been identified.
44 citations
TL;DR: In this paper, several cast-cured plastic bonded explosives (PBXs) based on cyclic nitramines bonded by a polyurethane matrix have been prepared and studied.
Abstract: Several cast-cured plastic bonded explosives (PBXs) based on cyclic nitramines bonded by a polyurethane matrix have been prepared and studied. The nitramines were ε-CL20 (ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12hexaazaisowurtzitane, ε-HNIW), BCHMX (bicyclo-HMX, cis-1,3,4,6tetranitro-octahydroimidazo-[4,5-d]imidazole), RDX (1,3,5-trinitro-1,3,5triazacyclohexane) and HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane). The detonation velocities were measured experimentally. The brisance of the prepared compositions was determined by the Kast method. The penetration performance of shaped charges filled with the prepared compositions was measured experimentally. The detonation parameters of the studied compositions and the individual explosives were calculated using the EXPLO5 thermodynamic code. It was concluded that CL20-HTPB has the highest detonation characteristics and performance of all of the prepared PBXs. BCHMX-HTPB is an interesting PBX with performance and detonation characteristics higher than those of RDX-HTPB. A linear relationship between the detonation pressures of the prepared PBXs and their performances in terms of the explosive brisance was observed; while the penetration depths formed by the shaped charge jets depended on the Gurney velocity of the studied PBXs samples.
35 citations
TL;DR: In this paper, an improved simple method is presented for calculation of the detonation velocity of CHNO and CHNOFCl explosives, as well as non-ideal explosives containing aluminum (Al) and ammonium nitrate (AN) additives.
Abstract: An improved simple method is presented for calculation of the detonation velocity of CHNO and CHNOFCl explosives, as well as non-ideal explosives containing aluminum (Al) and ammonium nitrate (AN) additives. In contrast to the available complex computer codes, where the estimated detonation velocities of non-ideal explosives for equilibrium and steady state calculations show significant differences from the measured data, this simple method gives more reliable results. Suitable decomposition paths are suggested in which the partial interaction of Al with the gaseous products and the decomposition of AN are assumed for composite explosives containing Al/AN additives. The predicted detonation velocities using the new method are good compared to those from one of the well-known empirical methods and from computer codes using full and partial equilibrium of Al/AN.
31 citations
TL;DR: A new energetic glycidyl-based polymer containing nitramine groups was synthesized using GAP as the starting material as discussed by the authors, showing better values regarding the energy of explosion (Delta U-E = -4813 kJ kg(-1)), the detonation velocity (V-Det = 7165 m.s.
Abstract: A new energetic glycidyl-based polymer containing nitramine groups (glycidyl nitramine polymer, GNAP) was synthesized using glycidyl azide polymer (GAP) as the starting material. The synthesis involved STAUDINGER azide-amine conversion, followed by carbamate protection of the amino group, nitration with nitric acid (100%) and trifluoroacetic anhydride and was concluded by deprotection with aqueous ammonia. The products obtained were characterized by elemental analysis and vibrational spectroscopy (IR). The energetic properties of GNAP were determined using bomb calorimetric measurements and calculated with the EXPLO5 V6.02 computer code, showing better values regarding the energy of explosion (Delta U-E = -4813 kJ kg(-1)), the detonation velocity (V-Det = 7165 m.s(-1)), as well as the detonation pressure (p(CJ) = 176 kbar), than the comparable polymers GAP and polyGLYN. The explosion properties were tested by impact sensitivity (IS), friction sensitivity (FS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and electrostatic discharge (ESD) equipment. The results revealed GNAP to be insensitive towards friction and electrostatic discharge, less sensitive towards impact (40 J) and a decomposition temperature (170 degrees C) in the range of polyGLYN.
31 citations
TL;DR: In this paper, the authors studied the penetration of a shaped charge jet with non-uniform density distribution and proposed a modified virtual origin model, which assumes a constant jet density, to include the situation where the jet density deficit/reduction of an un-sintered copper-tungsten powder jet causes a nonuniform jet density distribution.
Abstract: The penetration of a shaped charge jet with non-uniform density distribution was studied. The virtual origin model, which assumes a constant jet density, was modified to include the situation where the jet density deficit/reduction of an un-sintered copper-tungsten powder jet causes a non-uniform jet density distribution. A relation between the relative density ratio and the normalised jet velocity is proposed, based on which an analytical solution of the modified virtual origin model is obtained. The validity of the modified virtual origin model was demonstrated by its largely improved prediction in comparison with experimental and numerical results. It showed that the density reduction term reduces the penetration depth by 16.58% for an un-sintered copper-tungsten powder jet.
28 citations
TL;DR: In this article, the authors compared the optical sensitivities of two optical sensitizers, carbon black and a laser absorbing dye, in terms of optical power threshold for ignition, ignition delay and full burn delay at various laser powers.
Abstract: As a green technology, laser ignition of a relatively insensitive secondary explosive has been experimentally investigated. The explosive, hexanitrostilbene (HNS), was doped with one of two optical sensitizers, carbon black or a laser absorbing dye, and a continuous-wave (CW) infrared diode laser was used as the igniting source. The ignition sensitivities of HNS with each of the two optical sensitizers were analysed and compared in terms of: optical power threshold for ignition, ignition delay and full burn delay at various laser powers. The results have shown that both the chemical dye and carbon black optically sensitize the explosive with similar efficiencies. In contrast to the carbon black, the dye provides wavelength specificity and selectivity in the laser ignition process and its solubility in some specific solvents improves the coating of the explosive material. It was therefore concluded that the laser absorbing dye is a better candidate for optical sensitization in laser ignition than the commonly used carbon black. The combination of laser ignition sensitivity with wavelength selectivity potentially offers higher reliability and safety at a low optical power for future ignitors of secondary explosives.
24 citations
TL;DR: In this paper, the effect of additives on the phase transition of ammonium nitrate (V) was examined using differential scanning calcorimetry (DSC) and powder X-ray diffraction (XRD).
Abstract: A study has been undertaken on the effect of additives on the phase transition of ammonium nitrate(V) (AN). Results obtained using Differential Scanning Calorimetry (DSC) showed that organic compounds and potassium salts of organic compounds have an effect on the phase transition behavior of AN. The samples were further analyzed using infrared (IR) and powder X-ray diffraction (XRD). The mechanism of phase stabilization of AN by compounds of this kind was examined. The present study showed that the influence of additives on the phase transition of AN occurs through the polar groups that are involved in intermolecular interactions of orbital and electrostatic types that form new hydrogen bonds. AN exists in only one phase in the temperature range from 30 °C to +100 °C, when a potassium salt of organic compounds was added. However, with organic compounds, the III→II phase transition was changed. IR and XRD of composites are characterized by new intermolecular interactions. Compacted samples of AN containing potassium salts of organic compounds exhibited better stability than AN containing organic compounds to multiple cyclic changes within a temperature range. This we named 'freezing and thawing analysis'. Additives have two functions on the AN phase transition. First, solid solutions of AN mixture were formed for K + replacement of NH4 + . Second, hydrogen bonds formed, which caused AN and salts of organic compounds to interact intimately
23 citations
TL;DR: In this article, the detonation performance of four groups of aluminized explosives, namely, TNT, RDX, HMX, and RDX/AP-based, was examined through detonation experiments.
Abstract: The detonation performances of TNT-, RDX-, HMX-, and RDX/AP-based aluminized explosives were examined through detonation experiments. The detonation pressure, velocity, and heat of detonation of the four groups of aluminized explosives were measured. Reliability verification was conducted for the experimental results and for those calculated with an empirical formula and the KHT code. The test results on detonation pressures and velocities were in good agreement with the predicted values when aluminum (Al) particles were considered inert. The experimental heat of detonation values exhibited good consistency with the predicted values when a certain proportion of Al particles was active. Ammonium perchlorate (AP) can effectively reduce the detonation pressure and improve the heat of detonation for the RDX/AP-based aluminized explosive. A comparison of the current test results and literature data shows that errors may exist in early test data. The test data presented in this study allow for an improved understanding of the detonation performance of the four groups of aluminized explosives.
16 citations
TL;DR: In this paper, a simple method based on quantitative structure property relationship (QSPR) has been developed to give an accurate prediction of the crystal density of more than 170 polynitroarenes, poynitroheteroarenes and nitroaliphatics, nitrate esters and nitramines by suitable molecular descriptors.
Abstract: Abstract: The density of an energetic compound is an essential parameter for the assessment of its performance. A simple method based on quantitative structureproperty relationship (QSPR) has been developed to give an accurate prediction of the crystal density of more than 170 polynitroarenes, polynitroheteroarenes, nitroaliphatics, nitrate esters and nitramines as important classes of energetic compounds, by suitable molecular descriptors. The evaluation techniques included cross-validation, validation through an external test set, and Y-randomization for multiple linear regression (MLR) and training state analysis for artificial neural network (ANN), and were used to illustrate the accuracy of the proposed models. The predicted MLR results are close to the experimental data for both the training and the test molecular sets, and for all of the molecular sets, but not as close as the ANN results. The ANN model was also used with 20 hidden neurons that gave good result. The results showed high quality for nonlinear modelling according to the squared regression coefficients for all of the training, validation and the test sets (R2 = 0.999, 0.914 and 0.931, respectively). The calculated results have also been compared with those from several of the best available predictive methods, and were found to give more reliable estimates.
16 citations
TL;DR: In this article, two aluminized explosive compositions (RDX/Al/AP and RDX-Al/B/AP) have been analyzed, and their TNT equivalences were calculated according to the experimental data and the explosion law, showing that the addition of boron powders is a good way to enhance their blast effect, to improve the temperature of the explosion field and to prolong the duration of the higher temperature.
Abstract: Piezoelectric gauges were used to measure the shock wave overpressure of aluminized explosives and of a TNT charge. An infrared thermal-imaging spectrometer was used to collect the infrared signatures produced by the explosion fireball when the examined explosives were detonated. The measurement of the infrared signatures was used to estimate the surface temperatures and the dimensions of the fireball. Two aluminized explosive compositions (RDX/Al/AP and RDX/Al/B/AP) have been analyzed. 500 g charges of the aluminized explosives were prepared and studied, and their TNT equivalences were calculated according to the experimental data and the explosion law. The highest surface temperatures of the fireballs of these aluminized explosives were up to 1600 °C, which was higher than that of the TNT charge. In the region of the highest surface temperature above 700 °C, the duration for the composition RDX/Al/AP was about 232 ms (2.73 times more than TNT), whilst RDX/Al/B/AP was about 360 ms. The fireballs obtained from the explosion of these aluminized explosives had larger dimensions than that of TNT, especially when the surface temperature was above 1000 °C. The test results indicate that the addition of boron powders to aluminized explosives is a good way to enhance their blast effect, to improve the temperature of the explosion field and to prolong the duration of the higher temperature.
TL;DR: In this paper, a hydrogen-based emulsion explosive was devised to improve the power of traditional emulsion explosives, in spite of excellent water resistance, safe handling and good storage performance.
Abstract: Traditional emulsion explosives, in spite of excellent water resistance, safe handling and good storage performance, have low power problems which seriously hinders their use. In order to improve the power of emulsion explosives, a hydrogen based emulsion explosive was devised. Scanning electron microscope pictures and experimental storage results show that the coating effect and stability of coated magnesium hydride (MgH2) are very good. The power of an emulsion explosive sensitized by glass microballoons was significantly increased (24.30 mm compression of lead block) after adding coated MgH2, compared to only 16.10 mm compression when not added. Thus emulsion explosives with coated MgH2 as an energetic additive have many potential applications.
TL;DR: In this paper, the resistivities of different particle-size RDX and HMX were tested by a device designed and manufactured according to the standard ISO/IEC 80079-20-2:2016.
Abstract: The electrostatic hazards of nitramine explosives (RDX, HMX) were assessed in this paper. The resistivities of different particle-size RDX and HMX were tested by a device designed and manufactured according to the standard ISO/ IEC 80079-20-2:2016. This work shows that the resistivities of uncompacted RDX and HMX increase as the particle size decreases. Charging characteristics test experiments were also carried out using a so-called sieve method. Using this method, the influence of aperture size on charge accumulation of RDX was studied, and the characteristics of electrostatic accumulation of different particle-size RDX and HMX sieved with 50 mesh standard sieve were compared. The results show that the absolute value of the charge accumulation increases as the mesh number increases (i.e. the aperture size decreases), and increases as the particle size is decreased, indicating that nano-sized RDX and nano-sized HMX accumulate static electricity more easily than conventional micron-sized ones. Finally, the electrostatic discharge (ESD) sensitivity of nano-sized RDX and nano-sized HMX was investigated. Nano-sized nitramine explosives were found to have a higher ESD sensitivity than micron-sized ones.
TL;DR: In this article, an extensive NMR analysis of 3,3,4,4'-diaminoazoxyfurazan (DAAF) obtained by a new method that involves oxidation of 3-4-diaminofurazan to DAAF using a H2O2/HCOOH mixture.
Abstract: The aim of this study was an extensive NMR analysis of 3,3',4,4'-diaminoazoxyfurazan (DAAF) obtained by a new method that involves oxidation of 3,4-diaminofurazan to DAAF using a H2O2/HCOOH mixture. The raw product, after washing with water and drying, was min. 98% pure. We present proton, carbon and nitrogen NMR spectra of the prepared DAAF. Detailed analysis of the nitrogen spectrum gave interesting information about aromaticity of the substituted furazan rings.
TL;DR: In this article, the authors used the non-isothermal TG/DSC technique to study the kinetic triplet of the thermal decomposition of potassium chlorate at different heating rates (5, 10, 15 and 20 °C·min−1).
Abstract: The non-isothermal TG/DSC technique has been used to study the kinetic triplet of the thermal decomposition of potassium chlorate at different heating rates (5, 10, 15 and 20 °C·min−1). The DSC results showed two consecutive broad exothermic peaks after melting. The first peak contains a shoulder indicating the presence of at least two processes. The overlapped peaks were resolved by a peak fitting procedure, and the three resolved peaks were used for evaluation of the kinetic triplet for each step. The TG results also showed two consecutive mass losses after melting. The kinetics of the mass loss processes were studied using resolved DTG peaks. The activation energies were calculated using the KAS model-free method. The pre-exponential factor and the best kinetic model for each step were determined by means of the compensation effect, and the selected models were confirmed by the nonlinear model fitting method. The average activation energies obtained from the DSC results were 237.3, 293.8, and 231.3 kJ·mol−1 for the three consecutive steps of thermal decomposition of KClO3. The activation energies were 231.0 and 239.9 kJ·mol−1 for the first and second mass loss steps. The Avrami-Erofeev of Ax/y with the function of g(α) = [−ln(1−α)]x/y (x/y = 5/4 and 3/2) was the most probable model for describing the reaction steps.
TL;DR: In this paper, a bottom-up approach for the preparation of nano-aluminum powder (NAP) using a Transferred Arc Thermal Plasma Reactor (TAPR) is described.
Abstract: A bottom up approach for the preparation of Nano Aluminium Powder (NAP) using a Transferred Arc Thermal Plasma Reactor (TAPR) is described. The aluminium block is subjected to evaporation by the application of a thermal plasma. The aluminium vapour produced is rapidly quenched to room temperature resulting in crystallization of the aluminium vapour in nano-particulate form. Various process parameters, such as the plasma torch power, reactor pressure and plasma gas composition were optimized. This paper also describes the characterization of NAP by analytical methods, for the estimation of the Active Aluminium Content (AAC), Total Aluminium Content (TAC), XRD, bulk density, BET surface area, HR-TEM etc. The results are compared with those for samples prepared in other thermal plasma reactors, such as the DC Arc Plasma Reactor (DCAPR) and the RF Induction Thermal Plasma Reactor (RFITPR), and for commercially available NAP samples (ALEX, prepared by the EEW technique).
TL;DR: In this article, the phase transition of HNIW induced by heat was investigated with in situ X-ray powder diffraction (PXRD) and the effects of purity, particle size, insensitive additives and the time of isothermal heat treatment on the phase phase transition were evaluated.
Abstract: The ε→γ phase transition of HNIW induced by heat was investigated with in situ X-ray powder diffraction (PXRD). The effects of purity, particle size, insensitive additives and the time of isothermal heat treatment on the phase transition were evaluated. It was found that the phase transition is irreversible with changes in temperature, and the two phases can coexist in a certain temperature range. Moreover, the initial phase transition temperature increases with increasing purity and decreasing particle size of HNIW, and thus with the approximate crystal density. The addition of graphite and paraffin wax to HNIW as insensitive additives leads to a decrease in the initial phase transition temperature, but the addition of TATB does not affect the initial phase transition temperature. Thus, TATB is a suitable insensitive additive. Moreover, at the critical temperature, the isothermal time determined the efficiency of the εto γ-phase transition. This work lays the foundations for the choice of molding technologies, performance test methods, ammunition storage options, as well as the manufacture of HNIWbased explosive formulations.
TL;DR: In this article, the authors present their experience in the field of safe preparation and utilisation of HTP (98%+), a storable propellant that is finding use in various engineering applications.
Abstract: This paper presents the authors' experience in the field of the safe preparation and utilisation of HTP (98%+), a storable propellant that is finding use in various engineering applications. Brief characterisations of the material as well as examples of its potential use within relevant industries are provided. Additionally, some of the existing data and current research are included to demonstrate the full potential of this material which meets most of the needs of the propulsion industry. The laboratory technique for obtaining the substance that has been developed recently at the Institute of Aviation is briefly described. Utilisation of the method based on a special glass apparatus allows reproducible amounts of the substance to be obtained with relatively little risk.
TL;DR: In this paper, a tetrazole-phase-stabilized ammonium nitrate (PSAN) mixture was used as a gas-generating agent for air bags.
Abstract: New gas-generating agents for air bags have been investigated. Ammonium nitrate does not give off harmful gases nor leave solid residues but goes through contraction and expansion during a series of phase transitions that cause structural damage within the material. In this study, potassium-nitratephase-stabilized ammonium nitrate (PSAN) was prepared by a nonhazardous aqueous method. Ammonium nitrate-based propellants have low burning rates. Tetrazoles were selected as they have a large heat of formation and can be used as fuel components for ammonium nitrate-based gas-generating agents. A number of different experiments were conducted on the novel tetrazole/PSAN mixtures in order to evaluate their application as gas-generating agents.
TL;DR: In this article, the enhancement in the ballistic performance of double base rocket propellants (DBRPs) by the addition of different copper salts vs lead salts as burning rate modifiers through stable combustion and the formation of a plateau region in the low pressure region was discussed.
Abstract: This paper discusses the enhancement in the ballistic performance of double base rocket propellants (DBRPs) by the addition of different copper salts vs lead salts as burning rate modifiers through stable combustion and the formation of a plateau region in the low pressure region. Compositions based on DBRPs containing different percentages of lead stearate and different types of copper salts were prepared and studied. For comparison, a conventional DBRP was studied. The ignition temperature and heat of combustion were determined experimentally, and the mechanical properties were measured and evaluated. The performance in terms of ballistic characteristics (burning rate, operating pressure) were measured at different throat diameters (8, 8.5, 9, 9.5 mm) and at different temperatures (−20 and 50 °C). Specific impulses were calculated using the ICT thermodynamic code. The experimental data from the proportional study indicate that the compositions containing the studied burning rate modifiers are superior to the original DBRP in respect of ballistic performance and mechanical properties.
TL;DR: In this article, a palladium-based catalyst regeneration procedure was developed, which consists of heating the catalyst for a specific time at 350 °C in a nitrogen and water vapour stream, and allows partial recovery of the activity of the palladium catalyst in a subsequent HBIW hydrodebenzylation reaction.
Abstract: The polycyclic nitramine 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12hexaazaisowurtzitane (HNIW, CL-20) is synthesized via hydrodebenzylation of 2,4,6,8,10,12-hexabenzyl-2,4,6,8,10,12-hexaazaisowurtzitane (HBIW) over a palladium-based catalyst. This process is the key step in the synthesis of CL-20, a compound with unique energetic and explosive characteristics. The use of CL-20 is restricted at present by the high cost of the hydrodebenzylation process, during which the palladium-based catalyst becomes rapidly deactivated. The catalyst deactivation has now been shown to consist of deposition of the reaction products on the carbon support with simultaneous blocking of the active centers by these products. The HBIW decomposition products can permanently combine with palladium, thereby reducing the number of the active centers on the catalyst. Other byproducts clog the pores of the active carbon and reduce both the surface area of the active carbon and the pore volume. The reaction yield is also reduced by aggregation of palladium particles. A palladium catalyst regeneration procedure which has now been developed, consists of heating the catalyst for a specific time at 350 °C in a nitrogen and water vapour stream, and allows partial recovery of the activity of the palladium catalyst in a subsequent HBIW hydrodebenzylation reaction. The specific area and overall pore volume of the regenerated catalyst are also enhanced. The yield from the HBIW hydrodebenzylation reaction using the regenerated catalyst was ca. 42%.
TL;DR: In this paper, insensitive melt-cast explosive compositions based on 3-nitro-1,2,4-triazol-5-one (NTO) and containing TNT, wax, Al and RDX were evaluated.
Abstract: This paper presents research on insensitive melt-cast explosive compositions based on 3-nitro-1,2,4-triazol-5-one (NTO) and containing TNT, wax, Al and RDX. The viscosity of the compositions in the operating temperature range was measured. Thermal analysis was performed as well as thermal stability and sensitivity to mechanical and thermal stimuli were tested. The detonation parameters were also determined. Finally, the acceleration ability (Gurney energy) and the JWL coefficients for the detonation products were established.
TL;DR: In this article, the thermal damage in octahydro-1,3,5,7,tetranitro 1, 3, 5,7-tetrazocine (HMX) based plastic-bonded explosive (PBX) was investigated using in situ smallangle neutron and X-ray scattering techniques.
Abstract: The thermal damage in octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) based plastic-bonded explosive (PBX) was investigated using in situ smallangle neutron and X-ray scattering techniques. The microstructural evolution was quantitatively characterized by the model fitting parameters of total interfacial surface area (Sv) and void volume distribution. The Sv of HMX-PBX decreased markedly above 100 °C, indicating the movement of binder into the voids. After subsequent cooling to room temperature, the scattering intensity increased significantly with increasing storage time, and a new population of voids with average diameter of 20 nm was observed, accompanied by the gradual phase transition of HMX from δto β-phase. The experimental results implied that serious damage within the HMX-PBX was developed during storage after heating.
TL;DR: In this paper, the authors determined the thermobaric effect of cast composite explosives, with different masses and dimensions of the chosen explosive charges, at different distances from the center of the detonation.
Abstract: The aim of this research was to determine the thermobaric effect of cast composite explosives, with different masses and dimensions of the chosen explosive charges. This was done by measuring the shock wave parameters in air (maximum overpressure and pressure impulse) and quantifying the thermal effect (temperature-time dependence), at different distances from the centre of the detonation. The chosen thermobaric explosive composition, TBE-3, was characterized. Its density, detonation velocity and viscosity-time dependence were determined. Experimental samples of different masses and calibres were prepared. The shock wave parameters in air were determined in field tests, by measuring the overpressure by piezo-electric pressure transducers. The detonation and the expansion of the explosion products were filmed by a TV high-speed camera, Phantom V9. An infrared (IR) camera FLIR SC7200 was used for recording the IR scene of the explosions and for tracking the thermal effects by a thermographic technique, i.e. thermal imaging. This work is an initial step towards establishing a method for the quantification of the thermal effects of a thermobaric detonation.
TL;DR: In this article, a linear relationship between the impact sensitivity of nitroaromatic energetic compounds and their electric spark sensitivity was presented, where the root mean square and absolute standard deviation of a newly introduced correlation were respectively found to be 2.4 and 2.0 for 27 NER compounds.
Abstract: This study presents a linear relationship between the impact sensitivity of nitroaromatic energetic compounds and their electric spark sensitivity. The methodology assumes that the impact sensitivity of a nitroaromatic energetic compound with the general formula CaHbNcOd can be expressed as a function of the electrostatic sensitivity, the number of NH2 group substitutions in the 2,4,6-trinitrophenyl ring and non-additive structural parameters. The root mean square and absolute standard deviation of a newly introduced correlation were respectively found to be 2.4 and 2.0 for 27 nitroaromatic energetic compounds. The proposed new correlation was also tested for 7 additional nitroaromatic energetic compounds, which have complex molecular structures such as 1-(2,4,6-trinitrophenyl)-5,7-dinitrobenzotriazole and 1,3,7,9-tetranitrophenoxazine.
TL;DR: In this article, the results of investigations into the use of 56 nm nano iron(III) oxide as a combustion rate modifier in a solid heterogeneous rocket propellant (SHRP) were presented.
Abstract: This paper presents the results of investigations into the use of 56 nm nano iron(III) oxide as a combustion rate modifier in a solid heterogeneous rocket propellant (SHRP). A series of solid heterogeneous rocket propellants based on HTPB and ammonium perchlorate with different nano iron(III) oxide contents in the propellant composition were prepared and investigated. The ballistic parameters of the examined propellants were determined by combustion in a laboratory rocket motor (LRM). The ballistic properties were evaluated in the pressure range 5-10 MPa. It was found that the linear burning rate at 7 MPa was increased by 15% for 1% nano iron(III) oxide content in comparison to 0.2% content. Determination of the sensitivity to friction and impact, the calorific value, hardness and decomposition temperature of the derived propellants were
TL;DR: In this article, the authors investigated the relationship between the temperature sensitivity of deterred gun propellants and the burning rate of ball propellants using closed vessel tests and ballistic firing, respectively.
Abstract: One of the objectives of gun propellant research is to develop green formulations of gunpowder that should be less temperature sensitive than the current gun propellant. The temperature sensitivity of these new green formulations of the propellant should be measured to identify the less temperature sensitive green formulations. However, there are deficiencies in the methodologies for the measurement of the temperature sensitivity of gun propellants. Therefore, the aim of this investigation was to fill the gap by establishing a method for the measurement of the temperature sensitivity of deterred gun propellants by closed vessel tests. The temperature sensitivity of the burning rate of ball propellants and the temperature coefficients of gun performance were determined using closed vessel tests and ballistic firing, respectively. Specific definitions of temperature sensitivity and temperature coefficients were evaluated. The relation between these parameters has never been explicitly investigated previously. Assessing the temperature sensitivity of propellants by closed vessel tests is of added value to the range of ballistic tests if the results of these tests can be well correlated to the results of ballistic firings. Therefore, a comparison between both parameters was made. A correspondence has been observed between the temperature sensitivity of the propellant burning rate, as obtained from closed vessel tests, and the temperature coefficients as obtained from ballistic firings.
TL;DR: In this article, the compatibility of 2,6-diamino-3,5-dinitropyridine-1-oxide (ANPyO) with some energetic materials was studied by the use of differential scanning calorimetry (DSC).
Abstract: Abstract: For the application of 2,6-diamino-3,5-dinitropyridine-1-oxide (ANPyO) in composite explosives, the compatibility of ANPyO with some energetic materials was studied by the use of differential scanning calorimetry (DSC), where the energetic materials were cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitramine (HMX), 3,4-dinitrofurazanfuroxan (DNTF), hexanitrohexazaisowurtzitane (CL-20), 2,4,6-trinitrotoluene (TNT), 2,4,6-triamino-1,3,5-trinitrobenzene (TATB), 3-nitro-1,2,4-triazol-5-one (NTO), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), 5-amino-1H-tetrazole nitrate (5-ATEZN), ammonium perchlorate (AP), potassium perchlorate (KP), aluminum powder (Al), boron powder (B), magnesium hydride (MgH2) and magnesium borohydride (Mg(BH4)2). The results showed that the binary systems of ANPyO/ CL-20, ANPyO/NTO, ANPyO/5-ATEZN, ANPyO/Al, ANPyO/B, ANPyO/MgH2 and ANPyO/Mg(BH4)2 are compatible, and that the systems of ANPyO with RDX, LLM-105, HMX, AP and KP are sensitive, and with DNTF, TNT and TATB are incompatible.
TL;DR: In this article, hydroxyl terminated polybutadiene (HTPB) based sheet explosives were prepared incorporating the powerful explosive CL-20 as a partial replacement for hexahydro.
Abstract: The present investigation reports the use of 2,4,6,8,10,12-hexanitro2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) in sheet explosive formulations. In this study, hydroxyl terminated polybutadiene (HTPB) based sheet explosives were prepared incorporating the powerful explosive CL-20 as a partial replacement for hexahydro-1,3,5-trinitro-1,3,5-triazine(RDX). The effects of incorporating CL-20 on the performance, sensitivity, thermal and mechanical properties of the sheet explosive compositions are reported. Sheet explosive formulation containing 80% of RDX and 20% of HTPB-binder was studied as control sample. HTPBbinder consisted of 12% HTPB, 2.9% dioctyl adipate (DOA) and 5.1% dioctyl phthalate (DOP). HTPB was cured with 4,4’-methylene diphenyl di-isocyanate (MDI) to form urethane linkages. The incorporation of 20% of CL-20 in place of RDX led to a remarkable increase in the velocity of detonation (VOD), of the order of 7680 m/s, and to better mechanical properties in terms of tensile strength (1.14 MPa) compared to the control formulation [RDX /HTPB-binder (80/20)]. The 20% CL-20 incorporated sheet explosive formulation also showed remarkable increases in impact and shock sensitivity. Thermal analysis of the sheet explosive compositions has also been carried out using differential scanning
TL;DR: In this paper, the influence of processing techniques on mechanical properties and impact initiation behaviors of an Al-PTFE reactive material was evaluated using scanning electron microscopy (SEM) to identify the characteristics of the interior microstructures of the PTFE samples.
Abstract: Reactive materials (RMs) or impact-initiated materials have received much attention as a class of energetic materials in recent years. To assess the influence of processing techniques on mechanical properties and impact initiation behaviors of an Al-PTFE reactive material, quasi -static compression tests and drop-weight tests were performed. Scanning electron microscopy (SEM) was used to identify the characteristics of the interior microstructures of the Al-PTFE samples. A sintering process was found to transform Al-PTFE from a brittle to a ductile material with an increased elasticity modulus (from 108-160 MPa to 256-336 MPa) and yield stress (from 12-16 MPa to 19-20 MPa). Increasing the molding pressure from 36 MPa to 182 MPa increased the elastic modulus of all Al-PTFE samples and also the yield stress of unsintered ones. Unsintered samples in general required less energy to initiate than sintered ones. As the molding pressure increased, the impact initiation energy for sintered Al-PTFE fell from 96 J to 68 J, whereas the initiation energy for unsintered Al-PTFE rose from 68 J to 85 J. PTFE nanofiber networks observed in sintered samples formed under the higher molding pressures could contribute to the opposite trends observed in the impact initiation energy of unsintered and sintered Al-PTFE samples.