Hasil untuk "Explosives and pyrotechnics"

D. Badgujar, M. B. Talawar, S. N. Asthana et al.

J. Agrawal

Xiaoxiao Ma, Yuxiang Li, Iftikhar Hussain et al.

Energetic materials, including explosives, pyrotechnics, and propellants, are widely used in mining, demolition, automobile airbags, fireworks, ordnance, and space technology. Nanoenergetic materials (nEMs) have a high reaction rate and high energy density, which are both adjustable to a large extent. Structural control over nEMs to achieve improved performance and multifunctionality leads to a fascinating research area, namely, nanostructured energetic materials. Among them, core–shell structured nEMs have gained considerable attention due to their improved material properties and combined multiple functionalities. Various nEMs with core–shell structures have been developed through diverse synthesis routes, among which core–shell structured nEMs associated with explosives and metastable intermolecular composites (MICs) are extensively studied due to their good tunability and wide applications, as well as excellent energetic (e.g., enhanced heat release and combustion) and/or mechanical properties. Herein, the preparation methods and fundamental properties of the abovementioned kinds of core–shell structured nEMs are summarized and the reasons behind the satisfactory performance clarified, based on which suggestions regarding possible future research directions are proposed.

T. Klapötke

This graduate-level textbook treats the basic chemistry of high energy materials - primary and secondary explosives, propellants, rocket fuel and pyrotechnics - and provides a review of new research developments. Applications in both military and civil fields are discussed. This book also offers new insights into 'green' chemistry requirements and strategies for military applications. This work should be of interest to advanced students in chemistry, materials science and engineering, as well as all those working in defense technology.

Junying WU, Fude ZHENG, Yule YAO et al.

Shock initiation and ignition techniques driven by electrically exploded metallic bridge foils with insulating flyers have been widely implemented in initiation and ignition system of weapon. To address the deficiency in existing research regarding the description of the flow field evolution during the motion of flyer and promote the development of this technology towards efficient energy utilization and miniaturization, a double-pulse laser schlieren transient observation system was constructed. This system enables the acquisition of density distributions of the flow field and the motion distance of the flyer at different time. Additionally, a two-dimensional axisymmetric fluid dynamics calculation model and calculation method for the motion process of flyer driven by the electric explosion of metal foil were established, and corresponding numerical simulation calculations were performed in consideration of the evolution laws of the flow field inside and outside the acceleration chamber under the effects of the motion of flyer, the compression of shock wave, and the expansion of high-temperature and high-pressure plasma. The phase transition of bridge foil from solid phase to plasma phase was described by phase transition fraction, the state of plasma with high temperature and pressure was described by the state equation of plasma which consider the changes in particle number and coulomb interaction between particles, and the motion of flyer was described by dynamic grid model. The calculated flow field density distribution closely matches the experimental results, and the maximum errors in flyer motion distance and velocity are 6.1% and 8.1%, respectively, validating the accuracy of the calculation model and calculation method. The research results indicate that when the capacitance is 0.33 μF and the initiation voltage is 2800 V, within the research range, the maximum pressure in the flow field remains approximately 1×107 Pa; the temperature in the flow field gradually decreases from 9950 K at 516 ns to 3100 K at 2310 ns; and the plasma phase distribution in the flow field gradually evolves from a flat shape to a long strip shape, with the maximum diffusion distance of plasma in the direction perpendicular to the motion of the flyer being 0.8 mm. At 1360 ns, upon th flyer's breakthrough of the shock-wave front, a distinct bulge-shaped profile emerges in the leading edge of both pressure and temperature distributions within the flow field.

Qiang WANG, Jianjun WANG, Dan ZHAO et al.

To further explore the influence of interstitial C atom on the strain rate effect and temperature effect of CoCrNi-based medium-entropy alloy, the compression mechanical behavior, microstructure evolution and deformation mechanism of CoCrNiSi0.3C0.048 medium-entropy alloy were systematically studied at a wide temperature and strain rate range. The investigated alloy is composed of face-centered cubic (FCC) matrix and three-level precipitate microstructure, i.e. the primary Cr23C6 carbides (2−10 μm), the secondary SiC precipitates (200−500 nm), and the tertiary SiC precipitates (～50 nm). The results show that the serrated flow phenomenon is observed on the true stress-strain curve of the alloy at 400 ℃, and the amplitude of the serrations decreases gradually with the increase of strain and ultimately vanishes. In addition, the abnormal stress peak (the 3rd-type strain aging phenomenon) appears on the curve of the quasi-static flow stress with temperature, but at high strain rate, the abnormal stress peak disappears. Through the analysis of the characterization of the deformed microstructure, it is speculated that the main reason for the phenomenon of 3rd-type strain aging under quasi-static conditions may be the existence of interstitial C atoms. During the process of continuous plastic deformation and development, a series of mixed structures similar to heterogeneous structures are generated, which are composed of dense dislocation cells, micro bands, stack faults, dislocation clusters and deformation twins. These mixed structures intensify the interaction between interstitial atoms and moving dislocation, and then pin the dislocation, which results in dynamic strain aging phenomenon occurs. The reason why the 3rd-type strain aging does not appear under dynamic conditions may be that the solute atoms move slower than the dislocation. The dislocation cannot be pinned in time. In addition, the precipitation of a large number of nanoscale SiC precipitates weakens the "pinning" effect of interstitial atoms under dynamic loading.

Mengfei XU, Wentao MIAO, Weimin LIANG et al.

To investigate the dynamic characteristics and dynamic damage constitutive model of high-temperature bedding sandstone under cyclic impact, the physical properties of bedding sandstone after exposure to 300−1100 ℃ were first examined, and the influence of temperature on the color, mineral composition, mass and wave velocity of the specimens was recorded. Second, the dynamic characteristics of high-temperature bedding sandstone under cyclic impact were studied with a split Hopkinson pressure bar (SHPB) apparatus, and the dynamic responses of bedding sandstone at different strain rates and impact numbers were analyzed. Finally, on the basis of the visco-elastic damage element model for bedding rock, a dynamic constitutive model that accounts for high-temperature-impact-load coupling damage was established and verified against experimental data. The results show that the crystallization temperature of the dominant mineral quartz lies between 500 ℃ and 700 ℃; the higher the temperature, the darker the apparent color of the rock and the lower its mass. With increasing temperature, the wave velocity and peak stress first decrease and then increase. Temperature inflicts greater damage on 0° and 45° bedding sandstone, and the damage is most pronounced at 900 ℃. Under an impact voltage of 1300 V, the peak stress of bedding sandstone increases and then decreases with increasing impact number. Impact loading renders 0° bedding sandstone more susceptible to failure after high-temperature exposure, whereas 45° and 60° bedding sandstone exhibit strong impact resistance. The difference between the predicted and experimental curves is small, indicating that the model satisfactorily describes the cyclic-impact mechanical behavior of high-temperature bedding sandstone. The findings provide a valuable theoretical reference for the prevention and control of rock dynamic disasters in complex deep geothermal engineering environments.

Ashish Joshi, Kaushik Joshi, Rupali Kute et al.

High-Energy Materials (HEMs), particularly those integral to solid rocket motors are linchpins of mission success and safety. Detecting defects within a solid rocket motor is challenging but crucial for performance in aerospace and defense. Traditional methods and human inspection are inadequate, prompting the need for innovative defect detection. Our study introduces a deep learning approach, departing from conventional methods. Artificial intelligence-based automation is crucial for addressing the complexities and limitations of traditional defect detection methods. However, existing methods still grapple with challenges, in cases where images are non-defective, the conventional approach involves unnecessary annotation, leading to laborious efforts and computational costs. In some scenarios, low-quality images compromise feature extraction, impacting detection accuracy. To address this, our study introduces a novel approach. We employ a two-step process image classification and subsequent defect detection enhanced by dedicated neural network models. We start by classifying images as defective or non-defective using a unique combination for image classification that leverages the power of the Convolutional Autoencoder (CAE) in conjunction with the Visual Geometry Group Network-19 (VGG-19) architecture (CAE+VGG19). Only when an image is classified as defective, it proceeds to object detection and segmentation by Detectron2. Non-defective images bypass this step, thus saving valuable time and computational costs. This approach, not commonly found in previous studies. Our methodology achieves a remarkable 98% accuracy in image classification, in defect detection and segmentation, by Detectron2, accuracy exceeds 90%, ensuring precise localization. This study represents a significant advancement in Solid rocket motors (SRMs) defect detection, providing a precision-driven, efficient, and cost-effective solution.

V. Lysko, O. Mykytiuk

This review article discusses the practical use of calorimetric methods in materials science, in particular for studying phase transitions, determining heat capacity and thermal properties, investigating defects and structural changes, studying polymers, biomaterials, surface phenomena, etc. The application of microcalorimetry for monitoring explosives and pyrotechnics is highlighted.

Katherine M. Marczenko

Energetic materials (EMs), such as explosives, propellants, and pyrotechnics, play critical roles in various applications due to their rapid and intense energy release capabilities. Consequently, there is a need to balance performance with safety, ensuring that these materials can be used effectively while minimizing the risk of accidents. This perspective introduces and highlights the need for a bottom‐up approach to EM design that emphasizes structural considerations at the molecular, crystal, micro, and macro levels. Modifications to molecular architecture, engineering specific crystal packing patterns for optimal densities and reduced material sensitivity, and strategies for control of the microstructure, such as advanced crystallization techniques and the use of additives to increase energy density, are discussed. While the focus is on molecular and crystalline feedstocks that underpin performance and sensitivity, the broader development pipeline, including computational screening, scale‐up, qualification, and aging, is acknowledged and briefly contextualized. Collectively, the strategies outlined in this perspective represent a holistic strategy towards EM design.

Hongwei Zhu, Lianghe Sun, Ming-Jie Lu et al.

Xiaoran Liu, Jochen Ortmeyer, A. Bodach et al.

Abstract Energetic materials, mainly propellants, explosives, and pyrotechnics, are crucial in various civilian applications, such as fuels for rockets and spacecraft. Current energetic fuels rely on highly toxic and polluting ammonium perchlorate (AP) or carcinogenic hydrazine derivatives, encouraging the search for greener and safer substitutes. This work demonstrates the first use of amine‐AlH3 adducts as potential solid fuels with promising hypergolic properties, high energy content, and without toxic derivatives. The herein presented four amine‐AlH3 adducts, AlH3 coordinated with quinuclidine (Quin), triethylenediamine (TEDA), hexamethylenetetramine (HMTA), and tetraazatricyclododecane (TATD), illustrate a unique strategy to create new solid fuels by combining AlH3 with an energy‐rich nitrogen‐containing molecule. The crystal structures of new compounds ([HMTA‐AlH3]n and [TATD‐AlH3]n) are determined from powder X‐ray diffraction data. Differential scanning calorimetry‐thermogravimetric analysis (DSC‐TGA) of the samples combined with mass spectrometry (MS) evidence high thermal stability. The ultrashort ignition delays as low as one ms show an excellent hypergolic response. Four amine‐AlH3 adducts have higher combustion heat (> 29 kJ g−1) than conventional hydrazine fuels (19.5 kJ g−1). Finally, the successful mechanochemical syntheses of Quin2AlH3 and [HMTA‐AlH3]n are introduced, showcasing a green chemistry approach to energetic materials.

Wenjuan Li, Mingjie Wen, Jiahe Han et al.

Assessing the thermal stability of energetic materials (EMs) remains challenging due to the limitations of traditional experimental and computational methods. This study develops an optimized molecular dynamics (MD) protocol based on a neural network potential (NNP) to enable reliable quantitative prediction of EM thermal stability. Key improvements include the use of nanoparticle models and reduced heating rates.​ Systematic investigations on RDX show that nanoparticle structures mitigate decomposition temperature (Td) overestimation compared to periodic models, with surface effects dominating over particle size. Lower heating rates (e.g., 0.001 K/ps) further reduce deviation, bringing RDX Td within 80 K of experimental values (vs. > 400 K in conventional simulations). Kissinger analysis of the heating rate-Td relationship supports the feasibility of optimizing heating rates to align with experimental Td.​ Applied to eight representative EMs, the optimized protocol yields thermal stability rankings in excellent agreement with experiments (R2 = 0.96), outperforming traditional periodic models (R2 = 0.85). This work establishes a robust computational framework for EM thermal stability evaluation, particularly valuable in data-limited scenarios.

Guitao Liu, Kongxun Zhao, Yitong Liu et al.

To improve the aftereffect damage power of semi-armor-piercing-warhead (SAPW), this paper proposed a steel-zirconium laminated composite energetic penetrator. The penetration ability of laminated composite penetrators with different structure parameters was verified based on Ls-Dyna R11 finite element software, and steel-zirconium laminated composite material was prepared by wire arc additive manufacturing (WAAM). According to the finite element simulation results, the penetration ability of laminated composite penetrators was comparable to that of conventional homogeneous penetrators. Furthermore, during the penetration process, the steel casing acted as the momentous load-bearing component and collapsed after reaching the plastic deformation limit. Subsequently, the internal active zirconium shell was exposed to air and induced an energy release reaction, which fully demonstrated the structural advantages of laminated composite energetic penetrators. The microstructure analysis results show that the density of steel-zirconium laminated composite material prepared by WAAM exceeded 98 %, and there was a clear transition layer between steel and zirconium, indicating that the bonding strength between different deposition layers may be high. In addition, the steel deposition layer retained original structure, which means that the steel shell still had its original strength and ductile properties. The zirconium deposition layer was a two-phase mixture of Zr-riched phase and Fe-riched intermetallic compound. The presence of intermetallic compound further increased the brittleness of Zr shell, which helps to improve the energy release characteristics of laminated composite penetrators.

Maobo Yuan, Rui Wu, Jianwei Jin et al.

The erosion characteristics is an important reference index that affects the popularization and application of RDX-based high-energy gun propellant containing energetic plasticizer Diazidonitrazapentane (DIANP). For predicting the ablative properties of RDX-based high-energy gun propellants, the research prepared three kinds of propellant samples and performed erosion simulation tests. Based on the experimental results, the erosion kinetic model of the propellant gas to the barrel was derived from regression analysis and attribution analysis. Then, the Latin hypercube sampling method was used to generate a large number of the propellant formulations and working pressure combinations, and the ablative properties of these propellant formulations could be calculated by the erosion kinetic model. The propellant components and working pressure were set as characteristic values, and the corresponding ablative properties of these working conditions were taken as the response value to train the erosion prediction model of propellant based on machine learning. The results illustrated that the natural logarithm of mass loss and the reciprocal of explosion temperature showed strong linear relationships at different working pressure. Meanwhile, the influence of working pressure on erosion is more significant. Among the selected machine learning algorithms, the goodness of fit of the ensemble learning algorithm to sample data was 0.95, and the average relative deviation between the experimental data and predictive data was 8.93%, which demonstrated excellent prediction effect and generalization ability of the erosion prediction model based on ensemble learning. The aim of the erosion prediction model proposed in the study is to efficiently pre-evaluate the ablative property through the gun propellant formulation.

Chang LU, Chaolei HU, Jinze JIAO et al.

Lattice mechanical metamaterials have been widely used in various fields due to the lightweight, flexible designability and excellent impact resistance. In this paper, an enhanced X-shaped lattice mechanical metamaterial was designed and fabricated by selective laser melting. The dynamic crushing behavior and energy absorption mechanism of this metamaterials subjected to low-velocity impact were explored experimentally and numerically. The influence of impact velocity on the deformation mode and energy absorption capability of the enhanced X-shaped lattice mechanical metamaterials was analyzed. It is shown that the impact velocity has significant effects on the deformation modes of the mechanical metamaterials. At the lower impact velocities, the deformation mode of lattice mechanical metamaterials resembles that observed under quasi-static compression, characterized by the layer-by-layer crushing mode of the cells around the shear band. At the higher impact velocities, the deformation mode of lattice mechanical metamaterials transitions from X-shaped shear band to V-shaped shear band, and finally evolves into an arc-shaped shear band. The further study suggests that enhanced X-shaped lattice mechanical metamaterial exhibits a certain degree of velocity sensitivity. With the increase of the impact velocity, the initial peak stress, plateau stress, and specific energy absorption all increase correspondingly.

Davney Ondzié Pandzou, Nabil Mokrani, Stéphane Bernard et al.

Metal powders have both a high specific energy and a high energy density, which explains their widespread use in energetic materials (propellants, explosives and pyrotechnics). Pyrotechnic compositions are used extensively for both civilian and military applications. However, the combustion of pyrotechnics remains challenging to understand or predict due to the diversity of the components and the wide range of parameters that affect their results. Therefore, ongoing research efforts worldwide aim to investigate the combustion mechanisms of pyrotechnic compositions to improve their performance. In this review, studies on the ignition and combustion mechanisms of four metal powders (Al, Mg, Fe and B) are discussed. Moreover, their use as fuel in pyrotechnic systems is reported, as well as the combustion performance and energy release of the pyrotechnic mixtures. Additionally, some mixtures composed of fluorinated oxidizers and Al, Mg and B are also presented. Thermal analysis methods such as DSC and TG are used to obtain the thermal behavior of the pyrotechnic compositions. Furthermore, parameters such as particle size and the equivalence ratio that affect the performance of pyrotechnic mixtures and those that remain little studied are reported in this review.

Yanjun Wang, Yueguang Yu, Xin Zhang et al.

Amorphous boron powder, as a high-energy fuel, is widely used in the energy sector. However, its ignition and combustion difficulties have long limited its performance in propellants, explosives, and pyrotechnics. In this study, Mg/Al-coated boron powder with enhanced combustion properties was synthesized using the electrical explosion method. To investigate the effect of Mg/Al coating on the ignition and combustion behavior of boron powder, four samples with different Mg/Al coating contents (4 wt.%, 6 wt.%, 8 wt.%, and 10 wt.%) were prepared. Compared with raw B95 boron powder, the coated powders showed a significant reduction in particle size (from 2.9 μm to 0.2–0.3 μm) and a marked increase in specific surface area (from 10.37 m2/g to over 20 m2/g). The Mg/Al coating formed a uniform layer on the boron surface, which reduced the ignition delay time from 143 ms to 40–50 ms and significantly improved the combustion rate, combustion pressure, and combustion calorific value. These results demonstrate that Mg/Al coating effectively promotes rapid ignition and sustained combustion of boron particles. Furthermore, with the increasing Mg/Al content, the ignition delay time decreased progressively, while the combustion rate, combustion pressure, and heat release increased accordingly, reaching optimal values at 8 wt.% Mg/Al. An analysis of the combustion residues revealed that both Mg and Al reacted with boron oxide to form new multicomponent compounds, which reduced the barrier effect of the oxide layer on oxygen diffusion into the boron core, thereby facilitating continuous combustion and high heat release. This work innovatively employs the electrical explosion method to prepare dual-metal-coated boron powders and, for the first time, reveals the synergistic promotion effect of Mg and Al coatings on the ignition and combustion performance of boron. The results provide both experimental data and theoretical support for the high-energy release and practical application of boron-based fuels.

D. Kumar, Prajakta Uday Kotawadekar, Richa Singh et al.

This work focuses on the trace analysis of nitrate ion (NO3¯) content in post-blast explosion debris from pit soil samples and its control soil sample using Ion Chromatography (IC), an essential technique for inorganic explosives ion detection and confirmation. Blast simulations of pyrotechnics were conducted under a controlled environment in an agricultural land at Talegaon, Pune, India and a residential area at Nigadi, Pune, India. Explosion debris along with Pit Soil were collected from the pit of both sites. The control soil samples were collected from distance of 5 meters away from the explosion pits. A sensitive ion chromatographic method was used to detect the presence of nitrate ions in explosion debris and the control soil samples. The results provide insights into the interference caused by the common ions present both in explosion debris and the control soils. This study throws light on importance of testing of a control sample. The present study guides the forensic analyst in making correct interpretation of results based on comparative study of levels of nitrate ions in exhibits and its control.

Sebastian Górecki, A. Kudelko

Nitrogen-rich heterocycles constitute a family of high energy density materials (HEDMs) that have been developing intensively in recent years. A representative of this class is 1,2,4,5-tetrazine, a six-membered aromatic compound containing four nitrogen atoms in the ring. Many energetic compounds with this scaffold exhibit thermal stability, high density, and insensitivity to various stimuli, including friction, impact, and electrostatic discharge. This review presents methods for constructing 1,2,4,5-tetrazine precursors from acyclic reagents and describes their chemical modifications, leading to new energetic compounds with potential applications in the industry as explosives, propellants, or pyrotechnics. Synthetic procedures and reaction conditions are discussed, along with the detonation parameters of new nitrogen-rich tetrazine-based products, which allow estimation of their application potential.