Detonation Temperature Research Articles

Models for predicting impact sensitivity of energetic materials based on the trigger linkage hypothesis and Arrhenius kinetics

In order to predict the impact sensitivity of high explosives, we designed and evaluated several models based on the trigger linkage hypothesis and the Arrhenius equation. To this effect, we calculated the heat of detonation, temperature of detonation, and bond dissociation energy for 70 energetic molecules. The bond dissociation energy divided by the temperature of detonation proved to be a good predictor of the impact sensitivity of nitroaromatics, with a coefficient of determination (R2) of 0.81. A separate Bayesian analysis gave similar results, taking model complexity into account. For nitramines, there was no relationship between the impact sensitivity and the bond dissociation energy. None of the models studied gave good predictions for the impact sensitivity of liquid nitrate esters. For solid nitrate esters, the bond dissociation energy divided by the temperature of detonation showed promising results (R2 = 0.85), but since this regression was based on only a few data points, it was discredited when model complexity was accounted for by our Bayesian analysis. Since the temperature of detonation correlated with the impact sensitivity for nitroaromatics, nitramines, and nitrate esters, we consider it to be one of the leading predictive factors of impact sensitivity for energetic materials.

Simulation and Calculation of Interior Ballistic of A Large Caliber Artillery

Based on the classical interior ballistic model, the model is improved according to the actual situation. Relying on the newly established model, the related software is compiled. The maximum bore pressure, muzzle velocity and detonation temperature of a 155mm caliber gun are simulated by using relevant software. The maximum bore pressure is 338.2748 MPa, muzzle velocity is 855.1096 m/s and detonation temperature is 3468.402 K. After comparing the calculated results with the experimental data, it is found that the software is more practical and can be applied in engineering practice.

A molecular dynamics study and detonation parameters calculation of 5,5’-dinitramino-3,3’-bi[1,2,4-triazolate] carbohydrazide salt (CBNT) and its PBXs

ABSTRACT Molecular dynamics (MD) simulation has been used to investigate the new explosive 5,5ʹ-dinitramino-3,3ʹ-bi[1,2,4-triazolate] carbohydrazide salt (CBNT) and its polymer-bonded explosives (PBXs) with polymethyl methacrylate (PMMA), polyisobutylene (PIB), cellulose acetate butyrate (CAB) and polyurethane (Estane 5703). The binding energy, isotropic mechanical properties (tensile modulus, bulk modulus, shear modulus, and Poisson’s ratio) and moldability are reported for CBNT and its based PBXs. Moreover, the detonation parameters (detonation velocity, detonation pressure, detonation temperature, and detonation heat) of CBNT and CBNT-based PBXs are calculated using EXPLO5. The binding energy between each of the crystalline surfaces and each polymer is different, of which the descending order is CBNT/CAB > CBNT/Estane5703 > CBNT/PMMA > CBNT/PIB. The obtained mechanical properties results indicate that the mechanical properties of the CBNT can be effectively improved by adding a tiny amount of polymer binders and the ability of different polymer binders improving the plasticity and moldability of CBNT in the descending order of Estane 5703 > CAB > PMMA > PIB. The calculated detonation performances show that when 5% binders are added, the detonation velocity and detonation pressure of PBXs are lower than those of pure CBNT, of which the detonation velocity is higher than 8500 m/s and the detonation pressure is higher than 26 GPa. Due to the high enthalpy of formation, the detonation temperature and detonation heat of CBNT/CAB are larger than those of pure CBNT.

Simple method to calculate explosion temperature of ideal and non-ideal energetic compounds

ABSTRACTThe explosion (detonation) temperature of organic compounds containing energetic groups can be related to the study of the kinetics of chemical reactions in the reaction zone as well as the thermodynamic state of the detonation products. It can be predicted by a simple approach for ideal and less ideal energetic compounds as well as non-ideal composite explosives containing aluminum (Al) or ammonium nitrate (AN). A general correlation is introduced for calculation of the explosion temperature from the heat of detonation where it can be corrected for AN and liquid organic energetic compounds. For ideal and less ideal energetic compounds, the predicted results are compared with the outputs of complex thermochemical/hydrodynamic computer codes using two appropriate equations of state (BKWR-EOS and BKWS-EOS). The values of mean absolute percentage error (MAPE) in the explosion temperature for ideal and less ideal organic energetic compounds are 5.4, 5.5 and 12.5 for the new method, BKWS-EOS, and BKWR-EOS, respectively. The new method shows good agreement for non-ideal energetic compounds with respect to the outputs of BKWS-EOS using partial equilibrium where it provides good predictions for detonation performance.

Azide-Based High-Energy Metal-Organic Frameworks with Enhanced Thermal Stability.

We describe the structure and properties of [Zn(C6H4N5)N3]n, a new nonporous three-dimensional high-energy metal–organic framework (HE-MOF) with enhanced thermal stability. The compound is synthesized by the hydrothermal method with in situ ligand formation under controlled pH and characterized using single-crystal X-ray diffraction, elemental analysis, and Fourier transform infrared. The measured detonation temperature (Tdet = 345 °C) and heat of detonation (ΔHdet = −0.380 kcal/g) compare well with commercial explosives and other nitrogen-rich HE-MOFs. The velocity and pressure of denotation are 5.96 km/s and 9.56 GPa, respectively. Differential scanning calorimetry analysis shows that the denotation of [Zn(C6H4N5)N3]n occurs via a complex temperature-dependent mechanism.

Compensation method for infrared temperature measurement of explosive fireball

The temperature of explosive fireball is an important index for measuring the performance of explosives. Considering the harsh environment in the explosion field, the acquisition of fireball temperature depends mainly on the radiation temperature measurement method. The content of research on radiation temperature measurement in the explosion field includes two main points, namely, (1) how to measure the fireball radiation energy accurately and (2) how to convert the measured radiation energy into fireball temperature accurately. Theoretical studies on infrared temperature measurement in the explosion field are scarce. No theory is suitable for modifying fireball temperatures measured by IR system.A temperature compensation formula is proposed based on geometrical optics and infrared radiation theory in this study to eliminate the measurement error of radiation energy caused by the test environment. The principle of the influence of distance and meteorological conditions on measurement accuracy is analyzed. After eliminating the temperature error, image gray level is introduced as an intermediate variable, and the temperature compensation relationship is derived based on error transfer theory. Subsequently, the correctness of the theory is verified through simulation experiments. The measured temperature of 3 Kg of HMX mixing powder is compensated for and corrected. Compared with the original data, the revised values are closer to the detonation temperature of 2000 °C.

Three-dimensional numerical study on rotating detonation engines using reactive Navier-Stokes equations

Three-dimensional simulations on the rotating detonation engine (RDE) are conducted by solving the Navier-Stokes equations in stoichiometric hydrogen/air mixtures. Free-slip wall and non-slip wall boundary conditions are considered. The emphasis is placed on the effects of the viscosity, mass diffusion and thermal conduction on the detonation wave in the RDE, especially in the boundary layer. The simulation results show that the detonation wave propagates with a lower velocity in the Navier-Stokes solutions compared with that in the Euler solutions. This is mainly due to the effects of mass diffusion and thermal conduction. Meanwhile, the two effects above reduce the pressure of the detonation wave in the mainstream. Moreover, the detonation wave height is higher in the Navier-Stokes solutions than that in the Euler solutions. The temperature behind the detonation wave near the walls is much higher than that inside the chamber due to the existence of the boundary layer. Therefore, the viscosity, mass diffusion and thermal conduction impact the detonation velocity, pressure, the detonation wave height and temperature in the RDE.

Effect of particle gradation of aluminum on the explosion field pressure and temperature of RDX-based explosives in vacuum and air atmosphere

Abstract To optimize the energy output and improve the energy utilization efficiency of an aluminized explosive, an explosion device was developed and used to investigate the detonation pressure and temperature of R1 (Al6) aluminum powder and the aluminum powder particle gradation of R2 (Al6+Al13), R3 (Al6+Al24) and R4 (Al6+Al flake) in a confined space. By using gas chromatography, quantitative analysis and calculations were carried out to analyze the gaseous detonation products. Finally, the reaction ratios of the aluminum powder and the explosion reaction equations were calculated. The results show that in a confined space, the quasi-static pressures and equilibrium temperature of the aluminum powder in air are higher than in vacuum. In vacuum, the quasi-static pressures and equilibrium temperatures of the samples in descending order are R1>R3>R4>R2 and R3>R4>R1>R2, respectively. In air, the quasi-static pressures and equilibrium temperatures of the samples in descending order are R1>R2>R4>R3 and R1>R4>R2>R3, respectively. R4 (Al6+Al flake) and R3 (Al6+Al24) have relatively higher temperatures after detonation, which shows that the particle gradation method can enhance the reaction energy output of aluminum during the initial reaction stage of the explosion and increase the reaction ratio by 10.6% and 8.0%, respectively. In air, the reaction ratio of Al6 aluminum powder can reach as high as 78.16%, and the reaction ratio is slightly reduced after particle gradation. Finally, the reaction equations of the explosives in vacuum and in air were calculated by quantitative analysis of the explosion products, which provides a powerful basis for the study of RDX-based explosive reactions.

Ceramic Oxides from Liquid Explosive Reaction

This investigation promotes the design of emulsion explosives and the development of detonation theory on a microscale. As the total composition of oxidizing and reducing elements of the reactants leave related to the thermochemistry of the system, the computational details of predicting the temperatures of detonation were introduced. It was found that a significant improvement was achieved in the emulsion explosives with an aquiferous system. An improvement in the detonation synthesis of nanolithium and zinc oxides is due to the formation of an activated matrix of the metal nitrates’ oxidizer with the corresponding fuel. Temperatures of detonation of emulsion explosives and explosive formulations are predicted using thermochemistry information. The methodology assumes that the heat of detonation of an explosive compound of composition CaHbNcOdLieZnf can be approximated as the difference between the heats of formation of the detonation products and that of the explosive, divided by the formula weight of the explosive. For the calculations in which the first set of decomposition products is assumed, predicted temperatures of detonation of emulsion explosives with the product H2O in the gas phase have a deviation of 413.66 K from results with the product H2O in the liquid state. Fine-particle lithium and zinc oxides have been prepared by the detonation of emulsion explosives of the metal nitrates, M (NO3) x (M = Li, Zn) as oxidizers and paraffine as fuels, at high temperature and short reaction time. The detonation products were identified from X-ray powder diffraction (XRD) patterns, and transmission electron microscopy (TEM) measurements. XRD analysis shows that nanoparticles of lithium and zinc oxides can be produced from detonation of emulsion explosives due to fast quenching as well as appropriate detonation velocity and temperature.

Effect of wave shaper on reactive materials jet formation and its penetration performance

Abstract Wave shaper effect on formation behavior and penetration performance of reactive liner shaped charge (RLSC) are investigated by experiments and simulations. The reactive materials liner with a density of 2.3 g/cm3 is fabricated by cold pressing at a pressure of 300 MPa and sintering at a temperature of 380 °C. Experiments of the RLSC with and without wave shaper against steel plates are carried out at standoffs of 0.5, 1.0, and 1.5 CD (charge diameter), respectively. The experimental results show that the penetration depths and structural damage effects of steel plates decrease with increasing the standoff, while the penetration depths and the damage effects of RLSC without wave shaper are much greater than that with wave shaper at the same standoff. To understand the unusual experimental results, numerical simulations based on AUTODYN-2D code are conducted to discuss the wave shaper effect, including the propagation behavior of detonation wave, the velocity and temperature distribution of reactive jet, and penetration depth of reactive jet. The simulations indicate that, compared with RLSC without wave shaper, there is a higher temperature produced inside reactive jet with wave shaper. This unusual temperature rise effects are likely to be an important mechanism to cause the initiation delay time of reactive jet to decline, which results in significantly decreasing its penetration performance.

Tensile properties and microstructure evolution of compacted graphite iron at elevated temperatures

Attention has been focused on the fatigue problem for compacted graphite iron, when detonation pressure and temperature becomes higher and higher in combustion chamber for a long time. The compacted graphite iron plays an important role in the cylinder head of diesel industry for its good combination of thermal and mechanical properties. The damage mechanisms of compacted graphite iron under fatigue loading are observed in this study by scanning electron microscope (SEM) and in situ technique at elevated temperatures. The results show that tensile strength of compacted graphite iron decreases slightly at first, then decreases dramatically with the increasing temperature, which is a common phenomenon, even of various metallic materials. For the compacted graphite iron, these two stages are mainly controlled by different transformation mechanisms: the former mechanism, slip band stage, is affected by the inhibition of dislocation movement including strain strengthening, dynamic strain aging and precipitation hardening; and the latter, boundary sliding stage, is controlled by the vacancy diffusion. The newly proposed mechanisms can provide a new clue for the optimization of cast iron design. These damage mechanisms lay the foundation for the application of the crack technology.

Thermal Stability and Detonation Properties of Potassium 4,4'-Bis(dinitromethyl)-3,3'-azofurazanate, an Environmentally Friendly Energetic Three-Dimensional Metal-Organic Framework.

Environmentally acceptable alternatives to toxic lead-based primary explosives have become increasingly demanding for energetic materials (EMs) because of environmental concerns. Recent experiments suggested that energetic three-dimensional (3D) metal-organic frameworks (MOFs) are promising candidates for the next generation of environmentally friendly primary explosives. A new energetic 3D MOF, denoted as potassium 4,4'-bis(dinitromethyl)-3,3'-azofurazanate, was synthesized and suggested as an excellent candidate for green primary explosives. To achieve an atomistic-level understanding of the thermal stability and detonation properties of this material, we carried out quantum mechanics simulations to examine its initial decomposition mechanism and the Chapman-Jouguet state for sustainable detonation. We find that the initial decomposition reaction of potassium 4,4'-bis(dinitromethyl)-3,3'-azofurazanate is to break the C2N2O five-member ring in which K+ ions play a significant role in stabilizing the molecule structure, leading to an excellent thermal stability. Furthermore, this MOF system has a higher detonation velocity than that of lead azide, a comparable detonation pressure and temperature, and no toxic gases are produced at detonation. The combination of these detonation properties makes it a promising candidate for green EMs. Our results suggest that synthesizing 3D MOFs is an effective approach to develop environmentally acceptable alternatives to toxic EMs with enhanced thermal stability.

Influence of Silicon on the Detonation Performance of Energetic Materials from First-Principles Molecular Dynamics Simulations

The development of new generation energetic materials (EMs) with improved detonation performance is of considerable importance for applications in civilian and military fields, but there is no clear understanding about how the specific atom type and molecular structure control detonating properties. To gain an atomistic-level understanding of the influence of Si element on the detonation properties of EMs, we carried out the RxMD(cQM) procedure, combining ReaxFF reactive molecular dynamics with quantum mechanics molecular dynamics, to predict the thermodynamics parameters of the Chapman–Jouguet (CJ) state as measurements of detonation performance. We find that the detonation temperature for tetrakis(nitratomethyl)silane (Si-PETN) is higher than that for pentaerythritol tetranitrate (PETN) because of high energy release while forming Si products. However, lower detonation pressure and detonation velocity for the Si-PETN system than those for PETN system were found because Si atoms attract nearby oxygen ato...

Theoretical study for anisotropic responses of the condensed-phase RDX under shock loadings

We have performed quantum-based molecular dynamics (MD) simulations in conjunction with multiscale shock technique (MSST) to investigate the initial chemical processes and the anisotropy of shock sensitivity of the RDX under shock loading applied along the different directions. The results show that there is a difference between x (or y)-direction and z-direction in the response to a shock wave velocity of 12 km/s. It was shown that detonation temperature and pressure in the z-direction lags behind that of x-direction (or y-direction). Moreover, from the time evolution of the population of various key fragments, we also observe that along with z-direction significantly later than that of x (or y)-direction, which the reaction rate is also slower. Thus, we draw a conclusion that sensitive for shock propagation along x or y-direction, but less sensitive for shock propagation along z-direction.

Novel Organic Compounds Containing Nitramine Groups Suitable as High‐Energy Cyclic Nitramine Compounds

AbstractThis work introduces eight novel cyclic nitramine derivatives of energetic compounds as high performance energetic compounds. Assessments of physicothermal, detonation and combustion properties as well as sensitivities with respect to external stimuli impact, friction and shock are done for these compounds. The method of density functional theory (DFT) at B3LYP/6‐31G (d,p) as well as the best available predictive methods are used for prediction of 20 different parameters including crystal density, solid phase heat formation, Gibbs free energy of formation, activation energy, heat of sublimation, melting point, enthalpy of fusion, entropy of fusion, heat of combustion, heat of detonation, temperature of detonation, specific impulse, velocity of detonation, detonation pressure, Gurney velocity, power, brisance, heat sensitivity, impact sensitivity, friction sensitivity and shock sensitivity. These properties are compared with corresponding measured or calculated data of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) and 2,4,6,8‐tetranitro‐1H,5H‐2,4,6,8‐tetraazabicyclo [3.3.0] octane (BCHMX) as two high performance nitramines. Among the introduced cyclic nitramines, it shown that N,N‐bis(1,3,4,6‐tetranitrooctahydroimidazo[4, 5‐d]imidazol‐2‐yl) nitramide is a good candidate of high performance nitramine where its sensitivity with respect to impact, friction and shock is close to BCHMX.

Detonation temperature of an emulsion explosive with a polymer sensitizer

Dependences of the brightness temperatures of the detonation front and detonation products on detonation pressure were determined in the range of 0.7–9.4 GPa by a pyrometric method. The pressure was varied by changing the initial density of the emulsion explosive in the range of 0.43–1.2 g/cm3. Polymer microballoons were used as sensitizer. The dependence of the brightness temperature in the Chapman–Jouguet plane on detonation pressure was found to be nonmonotonic. In the investigated pressure range, the measured temperature values varied from 2250 to 1830 K. A comparative analysis of the application of polymer and glass microballoons as sensitizers was performed. The obtained experimental data were compared with the calculation results available in the literature.

Numerical simulation of the detonation of a propane-air mixture, taking irreversible chemical reactions into account

This work considers issues related to the numeric simulation of high-speed combustion and detonation of mixtures of carbonic fuel with air. Model problems are used to study the applicability of global kinetic mechanisms to describe the detonation of a propane-air fuel mixture. Problems of finding equilibrium adiabatic lines, determining Chapman-Jouguet detonation parameters, and the simulation of the structure of a stationary detonation wave were considered. Applying global kinetic mechanisms with irreversible chemical reactions may lead to overestimation of the detonation velocity and temperature of combustion products.

Synthesis of nano-diamond/alumina composite by detonation method

The nano-diamond/alumina composite was prepared by detonation with the boron-nano diamond, the aluminum isopropoxide and the RDX as raw materials in the present paper. The phase, morphology and structure of the explosive products were analyzed by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. The results indicated that the pressure and the temperature generated by explosion led the alumina to tightly coat the nano-diamond particles and to the composite nano-diamond/alumina particles formation, bonding with alumina. The size of the nano-diamond particle remained unchanged at 2–10nm and the composite particle size increased to 50–200nm. The alumina coating layer increased antioxidant properties of nanodiamond, increased the grain size composition of the polycrystalline powder. The Boron element had certain effects onto the oxidation coating, such as the diamond particles oxidation prevention during the preparation, the graphitization losses inversion, the detonation temperature increase and the high-temperature alumina composite particles proportion increase. The aluminum reduced gradually, which could lead to an increase in the density of the explosive composition, the detonation synthesis temperature to be reduced, the high-temperature alumina (such as the alpha-Al2O3) to decrease and all other alumina crystal types to increase.

Detonation Temperature of an Emulsion Explosive with a Polymer Sensitizer

Detonation Temperature of an Emulsion Explosive with a Polymer Sensitizer

High Performance Nitroazacubane Energetic Compounds: Structural, Thermochemical and Detonation Characteristics

AbstractIn this article, density functional theory (DFT) and electrostatic potential (ESP) analysis are used to predict enthalpy of sublimation, crystal density and enthalpy of formation for some isomers of 20 new derivatives of nitroazacubane as new high performance energetic compounds. These data are used to predict detonation and physicothermal properties of the mentioned compounds, including heat, pressure, velocity and temperature of detonation as well as deflagration temperature, melting point and entropy of fusion through appropriate theoretical methods. The predicted properties are compared with octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) as one of well‐known high performance energetic compounds. Detonation performance of nitroazacubane compounds are surprisingly much higher than HMX, which confirm that they can be introduced as novel high performance energetic compounds.