Detonation Temperature Research Articles

PREPARATION OF C60 BY DETONATION TECHNIQUE

A mixture of TNT (Trinitrotoluene) and natural graphite was detonated in a vacuum container which was immersed into cooling water; detonation products were collected for detecting. The results of mass spectroscopy, high performance liquid chromatography showed significant signals of C 60, which proved that C 60 could be synthesized by detonating the mixture of TNT/graphite and the detonation pressure was around 12.3 GPa and the detonation temperature was around 1985 K.

1-Amino-3-nitroguanidine (ANQ) in High-performance Ionic Energetic Materials

Abstract 1-Amino-3-nitroguanidine (ANQ, 2) was synthesized via hydrazinolysis of nitroguanidine (1). An appropriate Lewis structure of ANQ is drawn based on VB calculations. Due to its basicity, it can be protonated by strong mineral acids or acidic heterocycles. In order to synthesize new energetic materials the nitrate (3) and perchlorate (4) salts of 1-amino-3-nitroguanidine were synthesized by protonation of 2 with 40% nitric acid and 60% perchloric acid, respectively. 5-Nitrimino-1,4H-tetrazole obtained by reacting 5-amino-1H-tetrazole with 100% HNO3 was used to synthesize the nitriminotetrazolate salt 5. Furthermore, the dinitramide salt 6 of 1-amino-3-nitroguanidine was synthesized by metathesis reaction of silver dinitramide and 1-amino-3-nitroguanidinium chloride. The dinitroguanidinate salt 7 was synthesized by protonation of 2 with 1,3-dinitroguanidine, which was prepared from nitroguanidine in anhydrous nitric acid/N2O5. All compounds were fully characterized by singlecrystal X-ray diffraction, vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, and DSC measurements. The heats of formation of 2 - 7 were calculated using the atomization method based on CBS-4M enthalpies. With these values and the experimental (X-ray) densities several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code. In addition, the sensitivities towards impact, friction and electrical discharge were tested using the BAM drophammer, friction tester as well as a small-scale electrical discharge device. A Koenen test with 1-amino-3-nitroguanidinium nitrate (3) was carried out in order to evaluate its explosive performance and shipping classification.

Salts of Tetrazolone – Synthesis and Properties of Insensitive Energetic Materials

AbstractTetrazolone (5‐oxotetrazole, 1) is formed by diazotization of 5‐aminotetrazole in the presence of CuSO4. Nitrogen‐rich salts such as guanidinium (2), 1‐aminoguanidinium (3), 1,3‐diamino‐guanidinium (4), 1,3,5‐triamino‐guanidinium (5), ammonium (6), hydrazinium (7) and the hydroxylammonium (8) salts of tetrazolone were prepared by facile deprotonation or metathesis reactions. All compounds were characterized by single‐crystal X‐ray diffraction, vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis and DSC measurements. The heats of formation of 2–8 were calculated using the atomization method based on CBS‐4M enthalpies. With these values and the experimental (X‐ray) densities several detonation parameters such as the detonation pressure, velocity, energy and temperature were computed using the EXPLO5 code (V.5.04). In addition, the sensitivities towards impact, friction and electrical discharge were tested using the BAM drop hammer and friction tester as well as a small scale electrical discharge device.

CHNO Based Molecules Containing 2,2,2‐Trinitroethoxy Moieties as Possible High Energy Dense Oxidizers

AbstractTetrakis(2,2,2‐trinitroethyl) orthocarbonate (1) and 2,2,2‐trinitroethyl formate (2) were synthesized by the reaction of carbon tetrachloride, respectively chloroform, with the corresponding equivalents of 2,2,2‐trinitroethanol and catalytic amounts of anhydrous iron(III)chloride. 2,2,2‐Trinitroethyl formal (3) was prepared by the condensation of paraformaldehyde with 2,2,2‐trinitroethanol. The compounds were fully characterized by single‐crystal X‐ray diffraction, vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis, and multi‐temperature DSC measurements. Due to the positive oxygen balance, the suitability of all three compounds mentioned as potential oxidizers in energetic formulations was investigated and discussed. In addition, the heats of formation of the products were determined experimentally using bomb calorimetric methods. With this value and the experimental (X‐ray) density, several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code. Furthermore, the sensitivity towards impact, friction and electrical discharge was tested using the BAM drop hammer, a friction tester as well as a small‐scale electrical discharge device.

Energetic Nitrogen‐Rich Salts of 1‐(2‐Hydroxyethyl)‐5‐nitriminotetrazole

Abstract1‐(2‐Hydroxyethyl)‐5‐nitriminotetrazole (2) was formed by the reaction of 5‐amino‐1‐(2‐hydroxyethyl)tetrazole (1) and 100 % HNO3. Compound 1 was obtained by alkylation of 5‐amino‐1H‐tetrazole with 2‐chloroethanol. Nitrogen‐rich salts such as the ammonium (3), hydroxylammonium (4), guanidinium (5), aminoguanidinium (6), diaminoguanidinium (7), triaminoguanidinium (8), azidoformamidinium (9), and diaminouronium (10) 1‐(2‐hydroxyethyl)‐5‐nitriminotetrazolate were prepared by deprotonation or metathesis reactions. Compounds 3–10 were fully characterized by single‐crystal X‐ray diffraction (except for 9 and 10), vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC) measurements. The heats of formation of 4–10 were calculated by the atomization method based on CBS‐4M enthalpies. With these values and the X‐ray densities, several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code. In addition their sensitivities towards impact, friction, and electrical discharge were tested using a BAM drophammer, a friction tester, and a small‐scale electrical discharge device.

1-Nitratoethyl-5-nitriminotetrazole derivatives – Shaping future high explosives

1-(2-Nitratoethyl)-5-nitriminotetrazole ( 2) was formed by the reaction of 1-(2-hydroxyethyl-5-aminotetrazole ( 1) and 100% HNO 3. Compound 1 was obtained by alkylation of 5-amino-1 H-tetrazole. Next to the known byproduct 1-(2-hydroxyethyl)-5-nitriminotetrazole ( 3), a second one, 1-(2-nitratoethyl)-5-aminotetrazolium nitrate ( 4) was obtained and fully characterized. Nitrogen-rich salts such as the ammonium ( 5), hydroxylammonium ( 6), guanidinium ( 7), aminoguanidinium ( 8), diaminoguanidinium ( 9) and triaminoguanidinium ( 10) 1-(2-nitratoethyl)-5-nitriminotetrazolate were prepared by deprotonation or metathesis reactions. The reaction of 2 and diaminourea yielded 1-(2-nitratoethyl)-5-aminotetrazole ( 11). Compounds 4– 11 were fully characterized by single crystal X-ray diffraction, vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis and DSC measurements. The heats of formation of 5– 10 were calculated by the atomization method based on CBS-4M enthalpies. Regarding the possible application of these compounds as energetic materials or high explosives, several detonation parameters such as the detonation pressure, velocity, energy and temperature were computed using the EXPLO5 code and the X-ray densities as well as the computed heats of formation. In addition the sensitivities towards impact, friction and electrical discharge were tested using the BAM drophammer, a friction tester as well as a small scale electrical discharge device.

Calculation of Detonation Properties of Gaseous Explosives Using Generalized Reduced Gradient Nonlinear Optimization

AbstractIn this paper, a study on the development of a numerical modeling of the detonation of CHNO‐based gaseous explosives is presented. In accordance with the numerical model, a FORTRAN computer code named GasPX has been developed to compute both the detonation point and the detonation properties on the basis of Chapman–Jouguet (C‐J) theory. The determination of the detonation properties in GasPX is performed in chemical equilibrium and steady‐state conditions. GasPX has two improvements over other thermodynamic equilibrium codes, which predict steady‐state detonation properties of gaseous explosives. First, GasPX employs a nonlinear optimization code based on Generalized Reduced Gradient (GRG) algorithm to compute the equilibrium composition of the detonation products. This optimization code provides a higher level of robustness of the solutions and global optimum determination efficiency. Second, GasPX can calculate the solid carbon formation in the products for gaseous explosives with high carbon content. Detonation properties such as detonation pressure, detonation temperature, detonation energy, mole fractions of species at the detonation point, etc. have been calculated by GasPX for many gaseous explosives. The comparison between the results from this study and those of CEA code by NASA and the experimental studies in the literature are in good agreement.

Development of pressure and temperature gauges to monitor in situ performance of commercial explosives

A better understanding of the detonation performance of an explosive charge can be gained by directly measuring pressure, temperature and velocity of detonation (VOD). This is particularly important with explosives used in the mining industry because their performance is directly influenced by the degree of confinement given by the borehole diameter and the surrounding rock mass. A project funded by the Australian Coal Association Research Program (ACARP) was initiated in early 2009 with the view to design and build cost effective prototype instrumentation to measure the relative differences in detonation pressures and temperatures of commercial mining explosives. The project’s primary focus was on low density explosives. Low density (also referred to as low shock) explosives have been available in various forms for nearly 20 years. There have been significant advances in the availability, reliability and flexibility of these explosives which now offer a range of densities and degrees of water resistance. Their detonation performance is not well understood and cannot be accurately predicted with current ideal and non-ideal detonation codes. It was therefore viewed as important to be able to directly measure pressure and temperature during the detonation process of these complex mixtures in production blastholes. Identifying the pressure release patterns of both conventional and low density explosives under different geotechnical conditions should provide the necessary information to both validate detonation codes and better define input parameters for breakage and fragmentation models. This paper gives a general description of the prototype instrumentation developed and reports on the results obtained to date in both laboratory and full scale conditions.

N-Rich Salts of 2-Methyl-5-nitraminotetrazole: Secondary Explosives with Low Sensitivities

2-Methyl-5-nitraminotetrazole (1) was formed by nitration of 2-methyl-5-aminotetrazole. 2-Methyl-5-aminotetrazole was obtained by an improved synthesis starting from sodium 5-aminotetrazolate, which is methylated with dimethyl sulfate in dimethyl formamide giving 2-methyl-5-aminotetrazole in 29% yield. Nitrogen-rich salts such as guanidinium (2), 1-aminoguanidinium (3), 1,3-diamino-guanidinium (4), 1,3,5-triamino-guanidinium (5), azidoformamidinium (6), hydrazinium (7), diaminouronium 2-methyl-5-nitraminotetrazolate (8), as well as an urea adduct (9), were prepared by facile deprotonation or metathesis reactions. Diaminourea was synthesized by hydrazinolysis of dimethyl carbonate with hydrazine hydrate. All compounds were fully characterized by vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC) measurements. The crystal structures of 2-6, 8, and 9 could be determined using single crystal X-ray diffraction. The heats of formation of 2-9 were calculated using the atomization method based on CBS-4M enthalpies. With these values and the experimental (X-ray) densities several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code. In addition, the sensitivities toward impact, friction, and electrical discharge were tested using the BAM drop hammer, BAM friction tester, as well as a small scale electrical discharge device.

Design and implementation of high-speed multiwavelength pyrometry measurement system based on CMOS image sensor

The detonation temperature is measured both theoretically and experimentally by means of a complementary metal oxide semiconductors (CMOS) image sensor. An experimental system of multiwavelength temperature measurement based on CMOS image sensing technology is designed and realized. The instant spectral information of each moment is captured by row with the CMOS image sensor, depending on the unique characteristic of its rolling shutter. With the use of multiwavelength temperature measurement theory and by fitting spectrum emissivity through the regressive least square method, the color temperature of the detonation whose temperature is variable can be obtained continuously. The system is calibrated by measuring the standard spectrum of the laser. In our system, four time temperatures are measured within 10-µs detonation. Results show that the system has a higher measuring accuracy and speed, and can be applied in high-speed spectral information collection and storage during the detonation. OCIS codes: 230.0120, 280.0280, 320.0320. doi: 10.3788/COL201109.S10304.

Thermal effects on the Raman spectra of nanodiamonds

ABSTRACTWe report on the influence of the laser heating effect, potentially present in a Raman scattering experiment, on the behaviour of carbon phonon lines in the spectra of nanodiamond particles. Aside from the laser power used in the experiment, the extent of the thermal effect in question depends also on the nanodiamonds origin (obtained through detonation and high pressure high temperature techniques) as well as on the nanoparticles size. Laser heating should be properly taken into account when discussing Raman spectra of carbonaceous species, in particular, prior to addressing peak assignment and possible quantum confinement effects.

Numerical simulation of propane detonation in medium and large scale geometries

A modelling strategy has been developed for consequence analysis of medium and large scale gaseous detonation. The model is based on the solution of Euler equations with one-step chemistry. The Van Leer flux limited method which is a total variation diminishing scheme is used for shock capturing. Preliminary calculations were firstly conducted for small domains with fine grids which resolve the wave, relatively coarse grids which have less than 10 grids across the wave and coarse grids in which the minimum grid size is larger than the wave thickness to ensure that the reaction scheme has been properly tuned to capture the correct detonation pressure, temperature and velocity in the resolutions used in the different cases. The model was firstly tested against a medium scale detonation test in a shock tube with U-bends. Reasonably good agreement is achieved on detonation pressure and mean shock wave velocities at different measuring segments of the tube. Following the validation, the detonation of a hypothetical planar propane–air cloud is simulated. The predictions uncovered some interesting features of such large scale detonation phenomena which are of significance in the safety context, especially for accidental investigations. The findings from the present analysis are in line with the forensic evidence on damages in some historic accidents and challenges previous analysis of a major accident in which forensic evidence suggested localised detonation but was considered as the consequence of fire storms by the investigation team.

Titania Nanocrystalline Prepared by Detonation Method and Calculation of Detonation Parameters

AbstractAs a promising method for synthesizing nanosized materials, detonation method was used to prepare TiO2 nanoparticles. A new method for predicting the Chapman‐Jouguet (C‐J) detonation parameters of CaHbOcNdTie explosives, such as detonation heat, detonation temperature, and detonation pressure, was introduced according to the approximate reaction equations of detonation. The coefficient of oxygen balance of explosive was also calculated according to the specific detonation synthesis experiment. The calculation method was more useful in predicting the formation processes of detonation products and optimizing the experimental procedure. It could also support theory foundation for further experiments to some extent.

Performance enhancement of a pulse detonation rocket engine

Utilizing liquid kerosene as the fuel, oxygen as oxidizer and nitrogen as purge gas, a series of multi-cycle detonation experiments was conducted to improve the performance of pulse detonation rocket engine (PDRE). In order to improve the performance of the engine, it is crucial to develop an effective DDT enhancement device with less flow loss and higher survival in hostile detonation tube; therefore, three spiraling internal grooves were tested. The three spiraling internal grooves were semicircle, square and inversed-triangle grooves, respectively. The results showed that the spiraling internal groove can effectively enhance DDT and prolong the operation time of PDRE. The effect of groove shape on thrust enhancement of PDRE and the optimum length of spiraling groove were then investigated. To improve the detonability of liquid kerosene and prolong the durability of PDRE, experiments on the kerosene preheating based on active cooling were conducted. The results demonstrated that with the aid of fuel preheating, the detonation initiation time for liquid kerosene was noticeably reduced and a fully-developed detonation wave was achieved in the position away from igniter 4.67 times the diameter of the detonation tube. By adding the additive to liquid kerosene, the detonation initiation time from 0.75 ms decreased to 0.34 ms and the detonability of fuel was dramatically improved. Finally, experiments were conducted to investigate the effects of the operating frequency on the detonation parameters, the fill fraction and PDRE performance. The results indicated that detonation pressure and temperature vary with the operating frequency of PDRE, and the fill fraction has a significant influence on the specific impulse of PDRE. With the strategy of partial filling in detonation tube, the specific impulse can be remarkably enhanced.

CIS在瞬时多光谱爆温测量中的应用研究

The theory and experiment method to measure the detonation temperature by means of CIS are studied.A new type system,transient multi-wavelength detonation temperature measuring system,which is reasonable to practical measuring equipment,is presented.The system is calibrated by measuring the standard spectrum of the laser.Combined with multi-wavelength color temperature regression analysis arithmetic,the system is able to measure the temperature of fast varying halide tungsten light and its temperature varying curve with time.

Relationship Between the Low Temperature Thermolysis and Detonation Temperature of Carbocyclic Nitroaromatic Compounds

AbstractIn this paper, a new relationship between the activation energies (Ea) of the low temperature thermolysis and detonation temperature for different carbocyclic nitroaromatic compounds is introduced. Two structural parameters are needed to obtain a relatively good correlation for Ea. The resulting R2 value of the new correlation is 0.942. The new equation assumes that the calculated detonation temperature can be applied to predict Ea of carbocyclic nitroaromatic compounds with the general formula CaHbNcOd and any complicated molecular structure. The proposed new method was also used to predict Ea of some technologically attractive high thermostable polynitro arenes with complex molecular structure, e.g., 2,2′,2″,2′′′,4,4′,4″,4′′′,6,6′,6″,6′′′‐dodecanitro‐[1,3′,1′,1″] quaterphenyl (DODECA).

A new computer code to evaluate detonation performance of high explosives and their thermochemical properties, part I

In this paper a new simple user-friendly computer code, in Visual Basic, has been introduced to evaluate detonation performance of high explosives and their thermochemical properties. The code is based on recently developed methods to obtain thermochemical and performance parameters of energetic materials, which can complement the computer outputs of the other thermodynamic chemical equilibrium codes. It can predict various important properties of high explosive including velocity of detonation, detonation pressure, heat of detonation, detonation temperature, Gurney velocity, adiabatic exponent and specific impulse of high explosives. It can also predict detonation performance of aluminized explosives that can have non-ideal behaviors. This code has been validated with well-known and standard explosives and compared the predicted results, where the predictions of desired properties were possible, with outputs of some computer codes. A large amount of data for detonation performance on different classes of explosives from C–NO 2, O–NO 2 and N–NO 2 energetic groups have also been generated and compared with well-known complex code BKW.

World's highest solar plant installs Kyocera modules

In this paper a new simple user-friendly computer code, in Visual Basic, has been introduced to evaluate detonation performance of high explosives and their thermochemical properties. The code is based on recently developed methods to obtain thermochemical and performance parameters of energetic materials, which can complement the computer outputs of the other thermodynamic chemical equilibrium codes. It can predict various important properties of high explosive including velocity of detonation, detonation pressure, heat of detonation, detonation temperature, Gurney velocity, adiabatic exponent and specific impulse of high explosives. It can also predict detonation performance of aluminized explosives that can have non-ideal behaviors. This code has been validated with well-known and standard explosives and compared the predicted results, where the predictions of desired properties were possible, with outputs of some computer codes. A large amount of data for detonation performance on different classes of explosives from C–NO2, O–NO2 and N–NO2 energetic groups have also been generated and compared with well-known complex code BKW.

Explosive characteristics of aluminized HMX-based nanocomposites

The explosive characteristics of HMX compositions doped with 15% Al (by weight) were studied experimentally. The detonation velocity, pressure and temperature profiles, the velocity of endwise acceleration of plates, and the heat of explosion of dense pressed samples were measured. The results were compared for compositions based on mechanical mixtures of initial micron-size particles of HMX with aluminum powders of various sizes and for nanocomposites. The addition of nanoaluminum reduces the detonation velocity to a greater degree than the addition of micron-size aluminum. The mechanical mixtures have close detonation velocities, whereas in composites containing different types of nanoaluminum, they differ by almost 200 m/sec. For all compositions, except for the most homogeneous nanocomposite, two-peak pressure profiles are observed. For charges of a composite and a mechanical mixture with nanoaluminum of the same type, the second peak pressures almost coincide but are reached in different times. At the same time, the peak pressure increases with decreasing aluminum particle size. The temperature profiles agree qualitatively with the pressure profiles. The velocity of endwise acceleration of plates depends linearly on the activity of the aluminum powder used. Nanocomposites and mechanical mixtures containing the same aluminum powder have close heats of explosion. Nanoaluminum is almost completely oxidized during calorimeter bomb tests, and the major factor determining the heat of explosion of the compositions with nanoaluminum is also the content of active metal in the aluminum powder.

Mechanism of Thermal Unimolecular Decomposition of TNT (2,4,6-Trinitrotoluene): A DFT Study

The widespread and long-term use of TNT has led to extensive study of its thermal and explosive properties. Although much research on the thermolysis of TNT and polynitro organic compounds has been undertaken, the kinetics and mechanism of the initiation and propagation reactions and their dependence on the temperature and pressure are unclear. Here, we report a comprehensive computational DFT investigation of the unimolecular adiabatic (thermal) decomposition of TNT. On the basis of previous experimental observations, we have postulated three possible pathways for TNT decomposition, keeping the aromatic ring intact, and calculated them at room temperature (298 K), 800, 900, 1500, 1700, and 2000 K and at the detonation temperature of 3500 K. Our calculations suggest that at relatively low temperatures, reaction of the methyl substituent on the ring (C-H alpha attack), leading to the formation of 2,4-dinitro-anthranil, is both kinetically and thermodynamically the most favorable pathway, while homolysis of the C-NO(2) bond is endergonic and kinetically less favorable. At approximately 1250-1500 K, the situation changes, and the C-NO(2) homolysis pathway dominates TNT decomposition. Rearrangement of the NO(2) moiety to ONO followed by O-NO homolysis is a thermodynamically more favorable pathway than the C-NO(2) homolysis pathway at room temperature and is the most exergonic pathway at high temperatures; however, at all temperatures, the C-NO(2) --> C-ONO rearrangement-homolysis pathway is kinetically unfavorable as compared to the other two pathways. The computational temperature analysis we have performed sheds light on the pathway that might lead to a TNT explosion and on the temperature in which it becomes exergonic. The results appear to correlate closely with the experimentally derived shock wave detonation time (100-200 fs) for which only the C-NO(2) homolysis pathway is kinetically accessible.