Showing papers in "Propellants, Explosives, Pyrotechnics in 2004"
TL;DR: In this paper, a new approach to the production of nanocomposites of some energetic materials ( ammonium nitrite, cyclotrimethylene trinitramine (RDX), and aluminum) by the vacuum co-deposition technique is presented.
Abstract: Nanophase materials and nanocomposites, characterized by an ultra fine grain size (less than 100 nm) have attracted wide spread interest in recent years by virtue of their unusual mechanical, electrical, optical, magnetic, and energetic properties. Studies have shown that the thermal behavior of nano-scaled materials is quite different from micron-sized powders. Nanosized metallic and explosive powders have been used as solid propellant and explosive mixtures to increase efficiency. At the same time recent studies reveal that the presence of nanosized metals in propellants does not necessary translate into an increased burning rate and burning temperature. The reasons of this effect are far from being clear. This paper presents a new approach to the production of nanocomposites of some energetic materials – ammonium nitrite, cyclotrimethylene trinitramine (RDX), and aluminum – by the vacuum co-deposition technique. The thermal behavior of the synthesized nanopowder and nanocomposites is investigated. A substantial difference in burning rate of RDX nanopowder has been found in comparison to micron-sized material. Experimental results allow investigating the effects of nanosized materials on the combustion characteristics.
183 citations
TL;DR: In this article, a study of the decomposition behavior for ammonium perchlorate (AP) was carried out by differential thermal analysis and the two decomposition peaks were observed, and the high temperature peak was found to shift to lower temperatures, but the corresponding shift in the low temperature peak is smaller due to the effect of nanometer metal powders.
Abstract: A study of the decomposition behaviour for Ammonium Perchlorate(AP) was carried out by differential thermal analysis and the two decomposition peaks were observed. The high temperature peak was found to shift to lower temperatures, but the corresponding shift in the low temperature peak was smaller due to the effect of nanometer metal powders. Results shows that Cu and NiCu nanopowders decreased both the high and low decomposition temperature, while Ni and Al nanopowders just decreased the high decomposition temperature and increased the low decomposition temperature. Metal micron-sized powders show catalytic effects on the thermal decomposition of AP, but their effects are less than that of nanometer metal powders. With the increase in content, nanometer metal powders enhanced their catalytic effect on the high temperature decomposition of AP, however their effect was weakened on the low temperature decomposition.
159 citations
TL;DR: In this paper, the oxidation of Al-particles down to nano-scale was investigated by TG, SEM and in-situ X-ray diffraction, and the kinetic parameters of these two steps can be obtained by a model taking into account both reaction steps, chemical kinetics and diffusion for spherical particles when fitting it to TG-curves.
Abstract: The oxidation of Al-particles down to nano-scale was investigated by TG, SEM and in-situ X-ray diffraction. Al particles are usually coated by a 2-4 nm layer of Al{sub 2}O{sub 3} which can be derived from the degree of weight increase on complete oxidation by TG-curves. The low temperature oxidation of Al particles occurs at least in two steps. The first step builds a layer of 6 to 10 nm thickness composed of crystallites of the same size independent on the initial particle size. This reaction is dominated by chemical kinetics and converts a substantial fraction of the particle if the particle sizes decrease below 1 {mu}m, an effect carefully to be taken into account for nano-particles because of safety reasons. The second step combines diffusion and chemical reaction and proceeds therefore slowly, the slower the bigger the particles are. The kinetic parameters of these two steps can be obtained by a model taking into account both reaction steps, chemical kinetics and diffusion for spherical particles when fitting it to TG-curves. X-ray diffraction shows that particles smaller than 1 {mu}m build {gamma}- and {theta}-Al{sub 2}O{sub 3} in the first step with nano-crystalline structures which are then transformed to {alpha}-Al{sub 2}O{sub 3}. (Abstract Copyright [2004], Wiley Periodicals, Inc.)
102 citations
TL;DR: In this paper, a series of experiments using high-speed photography and pressure transducers were conducted to identify the dominant mechanism responsible for the propagation of reaction in MIC materials. But the authors did not identify the most likely mechanism for convection.
Abstract: Metastable Intermolecular Composite (MIC) materials are comprised of a mixture of oxidizer and fuel with particle sizes in the nanometer range. They are a subclass of materials known as thermites. The mechanism responsible for the propagation of reaction in loose compacts is not well understood. We have conducted a series of experiments using high-speed photography and pressure transducers in an attempt to identify the dominant mechanism. We studied a mixture of aluminum and molybdenum trioxide. Of the four possible candidates (radiation, convection, conduction, and acoustic/compaction), these preliminary studies identify convection as the most likely. However, the extent of contribution of the other modes is not yet known and this will receive further study.
95 citations
TL;DR: In this paper, the general synthetic methods used for the synthesis of inorganic, organic and metal dinitramide salts and their properties, with a special emphasis on ammonium dinitrameride.
Abstract: In recent years, there has been a considerable interest in the development of novel type of high performance propellants for use in solid rocket motors. Ammonium salt of dinitramidic acid NH4N(NO2)2 (ADN) has attracted wide interest as a potentially useful energetic oxidizer for rocket propellants because of its clean and environment-friendly exhaust products during burning. ADN contains one N(NO2)2 group and its synthesis requires new type of N-nitration. The present paper reviews the general synthetic methods used for the synthesis of inorganic, organic and metal dinitramide salts and their properties, with a special emphasis on ammonium dinitramide. The salient features with reference to the extent of conversion and ease of separation of the products of the various synthetic methodologies are also addressed.
92 citations
TL;DR: In this article, a nano-scale WO3 was synthesized using wet chemistry, where ammonium paratungstate was dissolved in acid and tungstic acid was precipitated by addition to distilled water.
Abstract: Tungsten oxides are of interest as an oxidant for metals in metastable intermolecular composites, a nano-scale powder useful for such applications as electric matches and gun primers. Smaller particles typically lead to faster reactions and we have synthesized nano-scale WO3 using wet chemistry. Ammonium paratungstate was dissolved in acid. Tungstic acid was precipitated by addition to distilled water and the resulting powder was dried. Analysis by X-ray diffraction, Raman spectroscopy and electron microscopy revealed hydrated WO3, having approximately 100 nm×7 nm platelet morphology. Thermal treatment in air at 200 °C or 400 °C removed water, forming cubic or monoclinic WO3, respectively. Tungsten forms other stable oxides and we accessed WO2 by reducing WO3 in dilute H2 at 650 °C. Reaction performance of these WOx-materials, mixed with nano-Al at various stoichiometries, is reported. Open-tray burn velocity reached 250 m/s. Pressure cell experiments found a maximum pressure of 1.45 MPa and maximum pressurization rate of 500 GPa/s. These maximum pressures and rates occurred very near a stoichiometric mixture of the Al and WO3.
74 citations
TL;DR: In this paper, the impact of physicochemical parameters on the sensitivity of I-RDX and normal RDX was analyzed and the role of the mean particle size on shock sensitivity was discussed.
Abstract: TNO Prins Maurits Laboratory has actively followed and contributed to the research on the development of insensitive munitions (IM). One of the initial research topics at TNO focused on the improvement of the shape of RDX crystals and its relation to the shock sensitivity. The variation of crystal shape has been studied by crystallization from different solvents and/or by post-treatment of the crystals. The role of the mean particle size on shock sensitivity was also included in these analyses. The decrease in shock sensitivity is even more pronounced when controlling the internal quality of crystals. In the meantime research has shifted to other energetic materials as well – in particular HMX and CL-20 – in this way revealing step by step the important physicochemical parameters which play a role in determining the shock sensitivity of formulations containing these types of nitramines. Various characterization techniques, to determine the internal and external quality of crystals will be discussed, and their relation to shock sensitivity in PBXs will be shown. Two different grades of I-RDX have been subjected to different characterization tests. The objective is to gain more understanding about which of the physicochemical parameters enables one to discriminate between a reduced sensitivity RDX and normal RDX.
59 citations
TL;DR: In this article, the rationale behind using heterocyclic compounds, particularly nitrogen heterocycles, as higher energy insensitive high explosives is discussed, including the potential advantages compared with carbocyCLic compounds.
Abstract: The rationale behind using heterocyclic compounds [1], particularly nitrogen heterocycles, as higher energy insensitive high explosives is discussed, including the potential advantages compared with carbocyclic compounds. The types of functional groups used to impart energy to heterocyclic nuclei, whilst maintaining insensitivity, and methodologies for their introduction, are covered. The latter include nitration (by conventional and clean synthetic methods), amination, and oxidation (on ring heteroatoms and of exocyclic amino groups). Strategies for maximising the energetic content of a given heterocyclic nucleus are also examined. The syntheses of specific examples at QinetiQ are described, based on the following nuclei: pyridine, pyrimidine, pyrazine, quinoxaline, quinazoline, pteridine and purine. Strategies for obtaining the desired amino-nitro derivatives and their heterocyclic N-oxides are outlined. Optimisation of the synthetic routes for several candidates is discussed. The physical, explosive and thermal properties of the more successful candidates are described, with suggestions for their potential application in military stores.
58 citations
TL;DR: Time-resolved emission experiments on deflagrating metastable interstitial composites of nano-aluminum and nano-molybdenum trioxide were performed in this paper, where the temperature obtained by fitting to a Planckian gray body appears accurate to better than ±100
Abstract: Time-resolved emission experiments on deflagrating metastable interstitial composites of nano-aluminum and nano-molybdenum trioxide were performed. Early in the experiment (before disassembly of the sample) the temperature obtained by fitting to a Planckian gray body appears accurate to better than ±100 K (at 3200 K). Spectral features due to Al and AlO species were observed on top of an apparent thermal background. The intensity of the AlO emission was observed to change with the ratio Al/MoO3, with larger AlO intensities associated with faster wave propagation speeds. Absolute irradiance output from the compressed powder samples was found to exceed that from a tungsten filament at the same apparent temperature.
56 citations
TL;DR: The enthalpies of combustion of dinitrobiuret and diaminotetrazolium nitrate (HDAT-NO3) were determined experimentally using oxygen bomb calorimetry.
Abstract: The enthalpies of combustion (ΔcombH) of dinitrobiuret (DNB) and diaminotetrazolium nitrate (HDAT-NO3) were determined experimentally using oxygen bomb calorimetry: ΔcombH(DNB)=5195±200 kJ kg−1, ΔcombH(HDAT-NO3)=7900±300 kJ kg−1. The standard enthalpies of formation (ΔfH°) of DNB and HDAT-NO3 were obtained on the basis of quantum chemical computations at the electron-correlated ab initio MP2 (second order Moller-Plesset perturbation theory) level of theory using a correlation consistent double-zeta basis set (cc-pVTZ): ΔfH°(DNB)=−353 kJ mol−1, −1 829 kJ kg−1; ΔfH°(HDAT-NO3)=+254 kJ mol−1, +1 558 kJ kg−1. The detonation velocities (D) and detonation pressures (P) of DNB and HDAT-NO3 were calculated using the empirical equations by Kamlet and Jacobs: D(DNB)=8.66 mm μs−1, P(DNB)=33.9 GPa, D(HDAT-NO3)=8.77 mm μs−1, P(HDAT-NO3)=33.3 GPa.
54 citations
TL;DR: In this article, the physical properties of the new tetrazene were determined by drop hammer and combined IR and MS pyrolysis experiments, and the structure and bonding were discussed on the basis of X-ray, MO and NBO analysis.
Abstract: 1,4-bis-[1-methyltetrazol-5-yl]-1,4-dimethyl-2-tetrazene a formal hexamer of diazomethane can be viewed as a new stable high energy density material (HEDM) with the properties necessary for a potential green chemistry gas generator. The physical properties of the new tetrazene were determined by drop hammer and combined IR and MS pyrolysis experiments. The structure and bonding are discussed on the basis of X-ray, MO and NBO analysis.
TL;DR: In this article, the synthesis and characterization of 1,5-diamino-1,2,3,4-tetrazolium perchlorate were carried out, and experimental evidence strongly supports the protonation of a nitrogen atom of the tetrazole ring.
Abstract: : The synthesis and characterization of 1 ,5-diamino- 1,2,3 ,4-tetrazolium perchlorate were carried out. Experimental evidence strongly supports the protonation of a nitrogen atom of the tetrazole ring, including the structure observed in a single crystal x-ray diffraction study of the title compound. Quantum chemical calculations were performed at the CCSD(T)/6-311G(2df,p)//MP2/6-311G(d,p) level of theory to determine the relative energies of all possible N-protonated structures of the 1,5.-diamino- 1,2,3,4-tetrazole ring. The predicted geometry of the most stable isomer compares favorably with the experimentally observed structure.
TL;DR: In this article, a laboratory synthesis of the energetic plasticizer n-buNENA was scaled up to one kg batch size and the compound was fully characterized by spectral data and elemental analysis.
Abstract: The laboratory synthesis of the energetic plasticizer n-buNENA was scaled up to one kg batch size and the compound was fully characterized by spectral data and elemental analysis. N-buNENA was formulated with CMDB and EDB propellant compositions. The results showed an improvement in mechanical properties and burning rate over a wide range of pressure along with acceptable limits of hazard and thermal stability as compared to DEP based propellant systems.
TL;DR: In this article, the authors carried out semi-empirical quantum mechanical molecular dynamics simulations involving collisions of two pentaerythritol tetranitrate (PETN) molecules at different molecular orientations and at several intermolecular separations.
Abstract: We have carried out semi-empirical quantum mechanical molecular dynamics (MD) simulations involving collisions of two pentaerythritol tetranitrate (PETN) molecules at different molecular orientations and at several intermolecular separations. The common features of reactive scattering among all molecular orientations are (1) the dissociation mechanism of PETN remains unimolecular and (2) the dominant reaction channel is the breaking of an ONO2 bond. However, the probability of collision-induced decomposition of PETN depends strongly on initial conditions, in agreement with the experimentally observed sensitivity of shock-initiated detonation in bulk PETN along different crystalline orientations. In addition, the next most frequent reaction path shows a dependence on initial orientations.
TL;DR: In this paper, a family of highly stable high nitrogen heterocycle 3,4,5-triamino-1,2,4-triazole (guanazine) with strong acids (HN03, HCl04, and "HN(N02)2") were characterized using spectroscopic as well as single crystal x-ray diffraction studies.
Abstract: : Reactions using the high nitrogen heterocycle 3,4,5-triamino-1,2,4-triazole (guanazine) with strong acids (HN03, HCl04, and "HN(N02)2") resulted in a family of highly stable salts. All of the salts were characterized using spectroscopic as well as single crystal x-ray diffraction studies. The x-ray structures are compared to that obtained from theoretical calculations (MP2/6-311+G(d,p) level). Initial safety testing (impact, friction) was carried out on all of the new materials.
TL;DR: In this paper, a constant metal-density model is proposed to take account of the thinning metal wall as the cylinder expands, which results in low values for full-wall standard, ideal explosives relative to CHEETAH analyses.
Abstract: The previous analysis of the Cylinder test required the treatment of different wall thicknesses and wall materials separately. To fix this, the Gurney analysis is used, but this results in low values for full-wall standard, ideal explosives relative to CHEETAH analyses. A new constant metal-density model is suggested, which takes account of the thinning metal wall as the cylinder expands. With this model, the inner radius of the metal cylinder moves faster than the measured outer radius. Additional small corrections occur in all cylinders because of energy trapped in the copper walls. Also, the half-wall cylinders have a small correction because the relative volumes of the gas products are smaller at a given outside wall displacement. The Fabry-Perot and streak camera measurements are compared. The Fabry method is shown to equate to the constant density model.
TL;DR: In this paper, a series of experiments involving ammonium dinitramide (ADN), a new energetic oxidizer of potential use in composite solid propellants, are described.
Abstract: This paper reports a series of experiments involving ammonium dinitramide (ADN), a new energetic oxidizer of potential use in composite solid propellants. The experiments include (a) self-deflagration of pressed pellets of ADN; (b) combustion of sandwiches with ADN laminae on both sides of a binder lamina that is either “pure” or filled with particulate oxidizer and other additives; and, (c) combustion of propellants with a bimodal oxidizer size distribution, wherein, combustion of coarse ADN and fine AP (ammonium perchlorate) and vice versa were used, in addition to mixtures of coarse ADN and AP, fine ADN and AP, and all-ADN or all-AP formulations.
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TL;DR: In this article, the authors performed a series of highly-instrumented experiments examining corner-turning of detonation and concluded that the detonation cannot turn the corner and subsequently fails, but the shock wave continues to propagate in the unreacted explosive leaving behind a dead zone.
Abstract: We have performed a series of highly-instrumented experiments examining corner-turning of detonation. A TATB booster is inset 15 mm into LX-17 (92.5% TATB, 7.5% kel-F) so that the detonation must turn a right angle around an air well. An optical pin located at the edge of the TATB gives the start time of the corner-turn. The breakout time on the side and back edges is measured with streak cameras. Three high-resolution X-ray images were taken on each experiment to examine the details of the detonation. We have concluded that the detonation cannot turn the corner and subsequently fails, but the shock wave continues to propagate in the unreacted explosive, leaving behind a dead zone. The detonation front farther out from the corner slowly turns and eventually reaches the air well edge 180° from its original direction. The dead zone is stable and persists 7.7 μs after the corner-turn, although it has drifted into the original air well area. Our regular reactive flow computer models sometimes show temporary failure but they recover quickly and are unable to model the dead zones. We present a failure model that cuts off the reaction rate below certain detonation velocities and reproduces the qualitative features of the corner-turning failure.
TL;DR: In this paper, the microstructural morphology of a plastic-bonded explosive, PBX 9501, was examined under varied confinement conditions, and significant changes in morphology, when compared to pristine material, contributed to higher gas permeability.
Abstract: Photomicrography and software-based quantitative image analysis were used to examine microstructural morphology of samples of a plastic bonded explosive, PBX 9501, which had been thermally damaged under varied confinement conditions. Samples were damaged to an advanced state, as would be attained just prior to cook-off. We observed significant changes in morphology, when compared to pristine material, which contribute to higher gas permeability. Changes included the formation of channels and pores, as well as fracturing of the HMX crystalline component. We discuss both qualitative and quantitative observations of morphology and whether they are likely to affect sensitivity and behavior of PBX 9501.
TL;DR: In this paper, the authors measured the deflagration behavior of several HMX-based explosives at extreme conditions (up to 520K and 1 GPa) in the LLNL High Pressure Strand Burner, thereby obtaining reaction rate data for prediction of violence of thermal explosions.
Abstract: We measure the deflagration behavior of energetic materials at extreme conditions (up to 520K and 1 GPa) in the LLNL High Pressure Strand Burner, thereby obtaining reaction rate data for prediction of violence of thermal explosions. The apparatus provides both temporal pressure history and flame time-of-arrival information during deflagration, allowing direct calculation of deflagration rate as a function of pressure. Samples may be heated before testing. Here we report the deflagration behavior of several HMX-based explosives at pressures of 10-600 MPa and temperatures of 300-460 K. We find that formulation details are very important to overall deflagration behavior. Formulations with high binder content (>15 wt%) deflagrate smoothly over the entire pressure range regardless of particle size, with a larger particle size distribution leading to a slower reaction. The deflagration follows a power law function with the pressure exponent being unity. Formulations with lower binder content ({le} 10% or less by weight) show physical deconsolidation at pressures over 100-200 MPA, with transition to a rapid erratic deflagration 10-100 times faster. High temperatures have a relatively minor effect on the deflagration rate until the HMX {beta} {yields} {delta} phase transition occurs, after which the deflagration rate increases by more than a factormore » of 10.« less
TL;DR: In this paper, the Gurney energy at infinite expansion has been used to compare the ability of an explosive to accelerate a metal with its ability to accelerate it, in the context of cylinder tests.
Abstract: After reconsidering the definition and characteristics of the Gurney energy, we explain some points related to the evaluation and practical use of this quantity. We correct a recently published relationship between the detonation velocity of an explosive and its Gurney energy at infinite expansion. Then, in the framework of cylinder tests, we indicate that the Gurney energy gives only a rough evaluation of experimental results; it can, however, be reasonably used to compare the ability of explosives to accelerate metals. Besides, the value γ=3 classically evoked for the polytropic gamma of the detonation products generally leads to significant errors in the evaluation of the Gurney energy at infinite expansion.
TL;DR: In this article, the combustion mechanisms of the mixtures 5-amino-1H-tetrazole/potassium nitrate and 5amino 1H tetrazoles/sodium nitrate have been examined, and it has been found that the burning rate increases with an increase in pressure.
Abstract: Recently, 5-amino-1H-tetrazole is developed for practical use as a substitute for sodium azide, which is conventionally used as a fuel component of gas generating agents for automobile airbags. In this study, the combustion mechanisms of the mixtures 5-amino-1H-tetrazole/potassium nitrate and 5-amino-1H-tetrazole/sodium nitrate have been examined. It has been found that the Granular Diffusion Flame model is applicable to the tested samples even when a molten layer exists at the burning surface. In addition, it is shown that within the pressure range of 1–5 MPa, the greatest factor which affects the burning rate is the diffusion process. It is also demonstrated that the fuel component decomposes first, and the oxidizer decomposes next. Meanwhile, it has also been confirmed that the burning rate increases with an increase in pressure because the flame approaches the burning surface and the amount of heat transfer to the solid phase increases. In spite of a decrease in the amount of heat transfer from the gas phase to the solid phase and an increase in the thickness of the condensed phase reaction zone for a mixture with higher fuel content, there are little differences in the burning rates probably because of an increase in the rate of decomposition of the solid phase.
TL;DR: In this paper, a means of comparing confinement effects both at constant radius and at constant detonation velocity is presented, and the results show two qualitatively different modes of behavior, i.e., a precursor pulse drives in the explosive ahead of the detonation front and a sharp shock wave in the metal.
Abstract: Reactive flow cylinder code runs on six explosives were made with rate constants varying from 0.03 to 70 μs. Six unconfined/steel sets of original ANFO and dynamite data are presented. A means of comparing confinement effects both at constant radius and at constant detonation velocity is presented. Calculations show two qualitatively different modes of behavior. For U/C≥ 1.2, where U, is the detonation velocity and C the zero-pressure sound speed in steel, we find a sharp shock wave in the metal. The shock passes through the steel and the outer wall has a velocity jump-off. For U/C, ≤ 1.04, we find a pressure gradient that moves at the detonation velocity. A precursor pulse drives in the explosive ahead of the detonation front. The outer wall begins to move outward at the same time the shock arrives in the explosive, and the outer wall slowly and continuously increases in velocity. The U C ≥ 1.2 cylinders saturate in detonation velocity for thick walls but the UC << 1.04 case does not. The unconfined cylinder shows an edge lag in the front that approximately equals the reaction zone length, but the highly confined detonation front is straight and contains no reaction zone information. The wall thickness divided by the reaction zone length yields a dimensionless wall thickness, which allows comparison of explosives with different detonation rates. Even so, a rate effect is found in the detonation velocities, which amounts to the inverse 0.15 0.5 power.
TL;DR: In this article, the enthalpies of polynitropyrazines and their N-oxides were obtained by designing isodesmic reactions and the detonation velocities by using the Stine method.
Abstract: The geometries of polynitropyrazines and their N-oxides have been fully optimized employing the density functional B3LYP method and the 6-31++G** basis set. For polynitropyrazines and their N-oxides we have obtained the enthalpies of formation (at p=1.013×105 Pa and T=298.15 K) by designing isodesmic reactions and the detonation velocities by using the Stine method. Calculated results show that the aromaticity of the pyrazine ring of polynitropyrazine is lower than that of its N-oxide. From the acquired relationship between the experimental impact sensitivity H50 (12B type) and the least CNO2 bond order the predicted H50 values for compounds 2,5-diamino-3,6-dinitropyrazine and 2,5-diamino-3,6-dinitropyrazine-1-oxide are 83 cm and 59 cm, respectively, implying that they are low sensitive explosives. The enthalpy of formation of polynitropyrazine is much less than that of its N-oxide. The calculated density (1.90 g/cm3) for 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) is close to the experimental value (1.918 g/cm3), and from both sensitivity and detonation velocity it has been deduced that LLM-105 is superior to other diaminodinitropyrazines and their N-oxides. The largest density and detonation velocity obtained in this work are 2.02 g/cm3 (2-amino-3,5,6-trinitropyrazine) and 9.34 km/s (2,3,5,6-tetranitropyrazine), respectively.
TL;DR: The application of lithium and its compounds in energetic systems and the behaviour of lithium species in flames is reviewed in this article, where the authors present a review of the literature on the use of lithium compounds in energy harvesting applications.
Abstract: The application of lithium and its compounds in energetic systems and the behaviour of lithium species in flames is reviewed. Both lithium metal and its compounds and alloys are versatile materials in either oxidizer, fuel and modifier applications for energetic systems. 116 references to the literature are given. For part II see Ref. [1].
TL;DR: In this article, the authors investigated the thermal decomposition of 3-nitro-2-4-dihydro-3H-1,2,4-triazol-5-one (NTO) in the temperature interval from 200 °C to 260 C using a glass Bourdon gauge.
Abstract: The kinetics of thermal decomposition of 3-nitro-2,4-dihydro-3H-1,2,4-triazol-5-one (NTO) in the temperature interval from 200 °C to 260 °C was investigated using a glass Bourdon gauge. The overall decomposition reaction includes two distinct stages: the fast first-order decomposition and the subsequent autocatalytic reaction. The importance of the first stage increases with increasing decomposition temperature and decreasing loading density of the Bourdon gauge (m/V). A period of preliminary heating, at a lower temperature, strongly influences the autocatalytic stage when the decomposition is carried out at a higher temperature. In the temperature domain 200–220 °C, the Arrhenius constants of the decomposition reaction are found to be close to the values usually observed for nitrocompounds: E=173 kJ/mol and log10k≈12.5 (s−1). It is shown that a simple model of NTO decomposition based on an autocatalytic reaction of the m-th order can describe the course of the decomposition at high temperature but the m number appears to be excessively high, up to 4. A new model of the decomposition is developed, including an initial monomolecular reaction, decomposition of the crystalline substance, and an autocatalytic reaction of NTO dissolved in liquid decomposition products. This model gives the common order of autocatalysis, m=1.
TL;DR: In this paper, the potential of strained fluorocarbons, which can act as oxidizers in metal-based pyrolant systems, is investigated by the enthalpy of combustion ΔcH(298K) and the fractional electron transfer ΔN.
Abstract: The potential of strained fluorocarbons, which can act as oxidizers in metal-based pyrolant systems, is investigated. The oxidizing performance of fluorocarbons is evaluated by the enthalpy of combustion ΔcH(298K) and the fractional electron transfer ΔN. ΔcH(298K) can be related to hybridisation, molar C/F ratio and strain of the parent carbon skeleton of the fluorocarbon. Considered fluorocarbons are tetrafluorotetrahedrane (CF)4 (3), tetrakis(trifluoromethyl)tetrahedrane C4(CF3)4 (4), hexafluoro[3]prismane (CF)6 (5), hexakis(trifluoromethyl)[3]prismane C6(CF3)6 (6), octafluorocubane (CF)8 (7), octakis(trifluoromethyl)cubane C8(CF3)8 (8), eicosafluorododecahedrane (CF)20 (9), eicosakis(trifluoromethyl)dodecahedrane C20(CF3)20 (10), C60F48 (11) and perfluorofullerane (CF)60 (12). Powerful oxidisers in terms of exothermicity are those possessing both tertiary CF-units and strained carbon skeletons. Nevertheless the reactivity, which is estimated on basis of ΔN, the fraction of electrons transferred according to Pearson, has been found to be high with the corresponding perfluoromethyl derivatives and maximum with the fluorofulleranes. For part IV see Ref. 17.
TL;DR: In this article, the impact velocity of stainless steel and titanium plates to grazing detonation of ANFO/perlite, the velocity of detonation were measured, using a new model which copes with an equation of state of low explosives.
Abstract: The work described here arose from a study into explosive welding. As part of that study, the impact velocity of stainless steel and titanium plates to grazing detonation of ANFO/perlite, the velocity of detonation were measured. Computer simulation required a new model which copes with an equation of state of low explosives.
TL;DR: In this article, the evolution of the sensitivity of a TATB composition after thermal cycles at elevated temperatures is analyzed and the results obtained for explosive decomposition, furazan generation, gas analyses and solid residue characterization.
Abstract: We analyze the evolution of the sensitivity of a TATB composition after thermal cycles at elevated temperatures. Sensitization due to thermal cycles is of variable magnitude depending on the kind of the second stimulus (mechanical or thermal). In order to investigate the possible mechanisms which govern these phenomena, we perform an extensive study of the evolution of the chemistry and microstructure of our composition and we determine the sensitivity of our explosive to various stimuli after various temperature/duration cycles. This first paper is devoted to the study of TATB chemical evolutions. We present the results obtained for explosive decomposition, furazan generation, gas analyses and solid residue characterization.