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20 pages, 3560 KiB  
Article
Study on Vibration Effects and Optimal Delay Time for Tunnel Cut-Blasting Beneath Existing Railways
by Ruifeng Huang, Wenqing Li, Yongxiang Zheng and Zhong Li
Appl. Sci. 2025, 15(15), 8365; https://doi.org/10.3390/app15158365 - 28 Jul 2025
Viewed by 153
Abstract
With the development of underground space in urban areas, the demand for tunneling through existing railways is increasing. The adverse effects of cut-blasting during the construction of tunnels under crossing existing railways are investigated. Combined with the principle of blasting seismic wave superposition, [...] Read more.
With the development of underground space in urban areas, the demand for tunneling through existing railways is increasing. The adverse effects of cut-blasting during the construction of tunnels under crossing existing railways are investigated. Combined with the principle of blasting seismic wave superposition, LS-DYNA numerical simulation is used to analyze the seismic wave superposition law under different superposition methods. This study also investigates the vibration reduction effect of millisecond blasting for cut-blasting under the different classes of surrounding rocks. The results show that the vibration reduction forms of millisecond blasting can be divided into separation and interference of waveform. Based on the principle of superposition of blasting seismic waves, vibration reduction through wave interference is further divided. At the same time, a new vibration reduction mode is proposed. This vibration reduction mode can significantly improve construction efficiency while improving damping efficiency. The new vibration reduction mode can increase the vibration reduction to 80% while improving construction efficiency. Additionally, there is a significant difference in the damping effect of different classes of surrounding rock on the blasting seismic wave. Poor-quality surrounding rock enhances the attenuation of seismic wave velocity and peak stress in the surrounding rock. In the Zhongliangshan Tunnel, a tunnel cut-blasting construction at a depth of 42 m, the best vibration reduction plan of Class III is 3 ms millisecond blasting, in which the surface points achieve separation vibration reduction. The best vibration reduction plan of Class V is 1 ms millisecond blasting, in which the surface points achieve a new vibration reduction mode. During the tunnel blasting construction process, electronic detonators are used for millisecond blasting of the cut-blasting. This method can reduce the vibration effects generated by blasting. The stability of the existing railway is ultimately guaranteed. This can improve construction efficiency while ensuring construction safety. This study can provide significant guidance for the blasting construction of the tunnel through the railway. Full article
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15 pages, 8324 KiB  
Article
Impact of a Variable Blockage Ratio on the Detonation Transition in a Pre-Detonator
by Yuchang Gil, Suhyeong Lee, Sangkyu Han and Sungwoo Park
Fire 2025, 8(7), 263; https://doi.org/10.3390/fire8070263 - 30 Jun 2025
Viewed by 631
Abstract
The deflagration-to-detonation transition (DDT) is a critical process for achieving reliable ignition in detonation-based propulsion systems, such as Rotating Detonation Engines (RDEs). This study experimentally investigates the effect of spatial variations in blockage ratio (BR) on flame acceleration and detonation onset within a [...] Read more.
The deflagration-to-detonation transition (DDT) is a critical process for achieving reliable ignition in detonation-based propulsion systems, such as Rotating Detonation Engines (RDEs). This study experimentally investigates the effect of spatial variations in blockage ratio (BR) on flame acceleration and detonation onset within a modular pre-detonator. Three DDT device configurations (converging, constant, and diverging) were designed to have an identical average BR of 0.5 and were tested over equivalence ratios ranging from 0.64 to 1.6. High-speed imaging, pressure transducers, and schlieren visualization were employed to characterize flame propagation velocity, pressure evolution, and exit wave structures. The converging configuration consistently promoted earlier detonation onset and higher success rates, especially under fuel-rich conditions (ϕ = 1.6), while the diverging configuration failed to initiate detonation in all cases. Enhanced flame compression in the converging layout led to strong coupling between the shock and reaction fronts, facilitating robust detonation formation. These findings indicate that the spatial distribution of BR, rather than average BR alone, plays a decisive role in DDT performance. This work offers validated design insights for optimizing pre-detonator in RDE applications. Full article
(This article belongs to the Section Fire Science Models, Remote Sensing, and Data)
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13 pages, 3624 KiB  
Article
Quasi-One-Dimensional Thermodynamic Analysis of Radially Expanding Laser-Supported Detonations
by Yuma Itakura, Kyohei Kato, Kimiya Komurasaki, Hokuto Sekine and Hiroyuki Koizumi
Aerospace 2025, 12(7), 584; https://doi.org/10.3390/aerospace12070584 - 28 Jun 2025
Viewed by 281
Abstract
Repetitively pulsed (RP) laser propulsion is regarded as an alternative to chemical rockets for space launches, potentially offering remarkable cost reductions. Understanding the physics of laser-supported detonation (LSD) is important for designing a high-performance propulsion system. Experimentally observed LSD propagation velocities are reportedly [...] Read more.
Repetitively pulsed (RP) laser propulsion is regarded as an alternative to chemical rockets for space launches, potentially offering remarkable cost reductions. Understanding the physics of laser-supported detonation (LSD) is important for designing a high-performance propulsion system. Experimentally observed LSD propagation velocities are reportedly lower than the Chapman–Jouguet (C-J) velocity; hence, a previous study that examined two-dimensional expansion behind the LSD to perform Hugoniot analysis using computational fluid dynamics (CFD) simulation resulted in strong detonation solution. In the present study, the effects of varying the relationship between heating and propagation velocity are investigated using CFD simulations. The findings indicate that a weak detonation solution was obtained with more realistic input of heating rate distribution and the pressure behind the LSD wave was lower than that in C-J detonation by a factor of three. The input LSD propagation velocity was changed by ±30% in the CFD simulation to examine the case of faster propagation in helium and slower propagation in argon and even so, a weak detonation mode was maintained. However, the input relaxation distance from the electron temperature to heavy particle temperature that is shorter in a light gas such as helium can produce a solution of C-J or strong detonation. Full article
(This article belongs to the Special Issue Laser Propulsion Science and Technology (2nd Edition))
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11 pages, 4432 KiB  
Article
Preparation, Crystal Structure, and Energetic Properties of Four 2,4,7,9-Tetranitro-10H-benzofuro[3,2-b]indole (TNBFI) Based Solvates
by Yiru Chen, Mi Yan, Chunbo Shi, Peilin Yang, Jinkun Guo, Yu Liu and Shiliang Huang
Chemistry 2025, 7(3), 96; https://doi.org/10.3390/chemistry7030096 - 9 Jun 2025
Viewed by 407
Abstract
Understanding the reactivity and the crystallinity of energetic materials in a solvent is significantly important for their synthesis, purification, and recrystallization. Here, the recrystallization of TNBFI (2,4,7,9-tetranitro-10H-benzofuro[3,2-b]indole), a primary explosive with good thermal stability, in different solvents was studied. Four TNBFI [...] Read more.
Understanding the reactivity and the crystallinity of energetic materials in a solvent is significantly important for their synthesis, purification, and recrystallization. Here, the recrystallization of TNBFI (2,4,7,9-tetranitro-10H-benzofuro[3,2-b]indole), a primary explosive with good thermal stability, in different solvents was studied. Four TNBFI solvates, including TNBFI·AC (AC = acetone), TNBFI·2DMSO (DMSO = dimethyl sulfoxide), TNBFI·4DIO (DIO = 1,4-dioxane), and TNBFI·ACN (ACN = acetonitrile), were obtained. The crystal structures of the solvates were determined by single-crystal X-ray diffraction (SCXRD). The molecular packing and intermolecular interactions in the solvate structures were investigated, and their energetic properties were predicted. Among them, TNBFI·ACN showed good detonation performance with a detonation velocity of 6228 m·s−1 and detonation pressure of 16.23 GPa, which was comparable to TNT and with a potential application in both ammunition and industry. These results will be helpful in the synthesis and purification of TNBFI and valuable for the design of the solvate structure for other energetic materials. Full article
(This article belongs to the Section Chemistry of Materials)
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24 pages, 7375 KiB  
Article
Effect of Silicone Rubbers on the Properties of RDX-Based PBXs and Their Application in the Explosive Hardening of Steel
by Konrad Szydło, Agnieszka Stolarczyk, Tomasz Jarosz, Barbara Lisiecka, Sylwia Waśkiewicz, Krzysztof Lukaszkowicz, Klaudiusz Gołombek, Jakub Polis and Mateusz Polis
Materials 2025, 18(10), 2311; https://doi.org/10.3390/ma18102311 - 15 May 2025
Viewed by 429
Abstract
Modern energetic materials (EMs) have many different civil applications. One of their most promising applications in civil engineering is explosive hardening, which facilitates the fast and cost-effective improvement of mechanical properties in the treated material. In this work, we present the results of [...] Read more.
Modern energetic materials (EMs) have many different civil applications. One of their most promising applications in civil engineering is explosive hardening, which facilitates the fast and cost-effective improvement of mechanical properties in the treated material. In this work, we present the results of our investigation on the explosive hardening of S235JR Steel with PBX formulations containing silicone binders and 1,3,5-trinitro-1,3,5-triazinane (RDX). In terms of safety, the impact (5–15 J) and friction (240–360 N) sensitivity of the tested plastic-bonded explosives (PBXs) was verified, simultaneously with DSC tests, energy of activation calculations, and critical diameter measurement. The developed material, prepared with techniques similar to the anticipated working conditions, is characterized by a high detonation velocity (up to 7300 m/s), low sensitivity for mechanical factors (10 J, 288 N), and a small critical diameter (3.3 mm). The developed PBX based on a silicone binder demonstrated grain fragmentation, recrystallization, and an increase in the surface hardness of S235JR steel, which was confirmed with SEM, EBSD, microstructure analysis, and microhardness studies. Full article
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14 pages, 1622 KiB  
Article
Study on Hydrogen Combustion Flame Acceleration Mechanism and Prediction Method During Severe Accidents in Nuclear Power Plants
by Ran Liu, Jingyi Yu, Xiaoming Yang, Yong Liu, Rubing Ma and Yidan Yuan
Energies 2025, 18(9), 2150; https://doi.org/10.3390/en18092150 - 22 Apr 2025
Viewed by 399
Abstract
Combustion caused by hydrogen-dominated combustible gas mixtures presents critical threats to nuclear safety during severe accidents in nuclear power plants, primarily due to their propensity for flame acceleration, deflagration, and subsequent detonation. Although the direct initiation of detonation from localized hydrogen accumulation at [...] Read more.
Combustion caused by hydrogen-dominated combustible gas mixtures presents critical threats to nuclear safety during severe accidents in nuclear power plants, primarily due to their propensity for flame acceleration, deflagration, and subsequent detonation. Although the direct initiation of detonation from localized hydrogen accumulation at critical concentrations remains challenging, flame acceleration can induce rapid pressure escalation and lead to deflagration-to-detonation transition under suitable conditions. The ultra-high-pressure loads generated almost instantaneously will pose serious risks to containment integrity and equipment or instrument functionality within nuclear facilities. This paper investigates the flame acceleration mechanism and criterion, which is crucial for precise hydrogen risk assessment. A hydrogen combustion flame acceleration model is developed, integrating both laminar and turbulent flame propagation across multiple control volumes. Validated against the RUT test, the model demonstrates high fidelity with a maximum 3.17% deviation in flame propagation velocity and successfully captures the pressure discontinuity. The developed model enables comprehensive simulation with improved predictive accuracy of the flame acceleration process, making it an essential tool for advancing fundamental understanding of hydrogen behavior and severe accident analysis. This model’s development marks a paradigm in nuclear safety research by providing an analytical instrument for integrated severe accident programs in nuclear power plants, contributing to improving the potential hydrogen risks assessment and management in next-generation reactor safety. Full article
(This article belongs to the Special Issue Thermal Hydraulics and Safety Research for Nuclear Reactors)
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13 pages, 3347 KiB  
Article
Small Deviations in Geometries Affect Detonation Velocities and Pressures of Nitroaromatic Molecules
by Danijela S. Kretić, Marija I. Maslarević and Dušan Ž. Veljković
Organics 2025, 6(2), 17; https://doi.org/10.3390/org6020017 - 9 Apr 2025
Cited by 2 | Viewed by 605
Abstract
Understanding the factors that affect the detonation performance of high-energy molecules (HEMs) is crucial for the design of novel explosives and fuels with desirable characteristics. While molecular factors, such as the presence of specific functional groups that give organic molecules explosive properties, are [...] Read more.
Understanding the factors that affect the detonation performance of high-energy molecules (HEMs) is crucial for the design of novel explosives and fuels with desirable characteristics. While molecular factors, such as the presence of specific functional groups that give organic molecules explosive properties, are key determinants of detonation characteristics, other factors like the geometry of molecules in crystal structures can also affect the high-energy properties of materials. Although it is known that slight deviations in the crystal structure geometry affect the sensitivity of nitroaromatic explosives, the influence of these variations on detonation performance remains unknown. In this study, we extracted different crystal structures of the same high-energy nitroaromatic molecules from the Cambridge Structural Database and calculated their detonation velocities and pressures using the Kamlet–Jacobs equations. Results indicated that different geometries of the same crystal structure can lead to non-negligible differences in detonation velocities and pressures. In the case of the 2,4,6-triamino-1,3,5-trinitrobenzene molecule, discrepancies in detonation pressures among different crystal structures were calculated to be 7.68%. Analysis of geometrical arrangements showed that these differences are mainly the consequence of diverse non-covalent bonding patterns that affect crystal densities. Full article
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15 pages, 6112 KiB  
Article
Study on the Mechanism of the Micro-Charge-Detonation-Driven Flyer
by Shuang Li, Jie Ren, Chang Leng, Zhenhao Shi, Yan Ma, Mingyu Li and Qingxuan Zeng
Micromachines 2025, 16(4), 441; https://doi.org/10.3390/mi16040441 - 9 Apr 2025
Viewed by 361
Abstract
To investigate the energy transfer mechanisms during the micro-explosive initiator-driven flyer process and to guide the performance evaluation of micro-sized charges and the structural design of micro-initiators, a combined approach of numerical simulations and experimental tests was employed to study the detonation process [...] Read more.
To investigate the energy transfer mechanisms during the micro-explosive initiator-driven flyer process and to guide the performance evaluation of micro-sized charges and the structural design of micro-initiators, a combined approach of numerical simulations and experimental tests was employed to study the detonation process of copper-based azide micro-charges driving a flyer. The output pressure and detonation velocity of the copper-based azide micro-charge were measured using the manganese–copper piezoresistive method and electrical probe technique, and the corresponding JWL equation of the state parameters was subsequently fitted. A simulation model for the micro-charge-driven flyer was established and validated using Photonic Doppler Velocimetry (PDV), and the influence of charge conditions, structural parameters, and other factors on the flyer velocity and morphology was investigated. The results indicate that the flyer velocity decreases as its thickness increases, whereas the specific kinetic energy of the flyer initially increases and then decreases with increasing thickness. The optimal flyer thickness was found to be in the range of 30 to 70 μm. The flyer velocity increases with the density and height of the micro-charge; however, when the micro-charge density exceeds a certain threshold, the flyer velocity decreases. The flyer velocity exhibits an exponential decline as the diameter of the acceleration chamber increases, whereas it shows a slight increase with the increase in the length of the acceleration chamber. The diameter of the acceleration chamber should not exceed the charge diameter and must be no smaller than the critical diameter required for detonation initiation of the underlying charge. The use of a multi-layer accelerating chamber structure leads to a slight reduction in flyer velocity and further increases in the transmission hole diameter while having no significant impact on the flyer velocity. Full article
(This article belongs to the Special Issue Micro/Nanostructures in Sensors and Actuators, 2nd Edition)
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14 pages, 3624 KiB  
Article
Polymeric Desensitizer Fluororubber: A Good Binder to Improve the Thermal Stability and Mechanical Properties of 3,4-Dinitrofurazanfuroxan
by Shenghui Wang, Xiaogang Mu, Yiming Luo, Ronghui Ju, Xuanjun Wang, Haixia Ma and Jijun Xiao
Molecules 2025, 30(8), 1665; https://doi.org/10.3390/molecules30081665 - 8 Apr 2025
Viewed by 368
Abstract
3,4-Dinitrofurazanfuroxan (DNTF) is characterized by its high energy, high detonation velocity, strong explosive power, and small critical diameter for detonation. However, its practical application is limited by poor thermal stability and mechanical properties. In this study, the polymeric desensitizer fluororubber (F2603) was introduced [...] Read more.
3,4-Dinitrofurazanfuroxan (DNTF) is characterized by its high energy, high detonation velocity, strong explosive power, and small critical diameter for detonation. However, its practical application is limited by poor thermal stability and mechanical properties. In this study, the polymeric desensitizer fluororubber (F2603) was introduced as a binder to enhance the overall performance of DNTF. Molecular dynamics (MD) simulations were used to investigate the thermal stability (trigger bond length and cohesive energy density (CED)) and mechanical properties, including elastic coefficient (Cij), tensile modulus (E), bulk modulus (K), shear modulus (G), Cauchy pressure (C12–C44), and Poisson’s ratio, for both pure DNTF (1 1 1) and DNTF (1 1 1)/F2603 composite systems at varying temperatures. The thermal stability was further experimentally investigated using differential scanning calorimetry (DSC) technique. The results demonstrated that the addition of F2603 leads to a shorter trigger bond length, higher CED, and a 7.2 kJ·mol−1 increase in activation energy (Ea), indicating improved thermal stability. Additionally, mechanical property simulations indicated that F2603 decreased the E, K, and G of DNTF while increasing the K/G ratio, suggesting enhanced mechanical toughness. These studies have important implications for the formulation design and practical application of DNTF and its composites. Full article
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18 pages, 12292 KiB  
Article
Role of -SF5 Groups in Modulating the Stability and Energy Characteristics of Fluorinated Molecules
by Jelena Tamuliene and Jonas Sarlauskas
Energies 2025, 18(7), 1841; https://doi.org/10.3390/en18071841 - 5 Apr 2025
Viewed by 513
Abstract
In this paper, we present our investigations into the detonation performance and stability variations caused by replacing the -CF3 or -OCF3 group with -SF5. The widely applied DFT B3LYP/cc-pVTZ approach was employed to evaluate the HOMO–LUMO gap, cohesive energy, [...] Read more.
In this paper, we present our investigations into the detonation performance and stability variations caused by replacing the -CF3 or -OCF3 group with -SF5. The widely applied DFT B3LYP/cc-pVTZ approach was employed to evaluate the HOMO–LUMO gap, cohesive energy, chemical hardness, and electronegativity. Based on these parameters, we predict the changes in chemical and thermal stability resulting from the inclusion of -SF5 instead of -CF3 or -OCF3. Our results indicate that, in some cases, the density of fluorine-containing nitro compounds decreases due to the presence of the pentafluorosulfanyl group. Additionally, machine learning techniques were used to determine the detonation pressure and velocity of fluorine–sulfur-containing compounds. Our findings suggest that fluorine-containing nitro compounds exhibit better detonation performance and stability than fluorine–sulfur-containing ones. Overall, the pentafluorosulfanyl groups inclusion of aromatic polynitro compounds improved neither the stability nor the detonation properties such as -CF3 or -OCF3 groups. Full article
(This article belongs to the Special Issue Advanced Energy Materials: Innovations and Challenges)
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22 pages, 5710 KiB  
Article
Experimental Characterization of Cast Explosive Charges Used in Studies of Blast Effects on Structures
by Anselmo S. Augusto, Girum Urgessa, Caio B. Amorim, Robison E. Lopes Júnior, Fausto B. Mendonça, José A. F. F. Rocco and Koshun Iha
CivilEng 2025, 6(2), 20; https://doi.org/10.3390/civileng6020020 - 4 Apr 2025
Cited by 1 | Viewed by 1827
Abstract
Structural research teams face significant challenges when conducting studies with explosives, including the costs and inherent risks associated with field detonation tests. This study presents a replicable method for loading spherical and bare TNT-based cast explosive charges, offering reduced costs and minimal risks. [...] Read more.
Structural research teams face significant challenges when conducting studies with explosives, including the costs and inherent risks associated with field detonation tests. This study presents a replicable method for loading spherical and bare TNT-based cast explosive charges, offering reduced costs and minimal risks. Over eighty TNT and Composition B charges (comprising 60% RDX, 39% TNT, and 1% wax) were prepared using spherical molds made of thin aluminum, which are low-cost, off-the-shelf solutions. The charges were bare, meaning they lacked any casing, as the molds were designed to be easily removed after casting. The resulting charges were safer due to their smaller dimensions and the absence of hazardous metallic debris. Composition B charges demonstrated promising results, with their performance characterized through blast and thermochemical experiments. Comprehensive data are provided for Composition B charges, including TNT equivalence, pressures, velocity of detonation, DSC/TGA curves at four different heating rates, activation energy, peak decomposition temperatures, X-ray analysis, and statistics on masses and densities. A comparison between detonation and deflagration processes, captured in high-speed footage, is also presented. This explosive characterization is crucial for structural teams to precisely understand the blast loads produced, ensuring a clear and accurate knowledge of the forces acting on structures. Full article
(This article belongs to the Section Structural and Earthquake Engineering)
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15 pages, 7645 KiB  
Article
Design and Performance Studies on Series of Tetrazole-Based Ultra-High-Energy Density High-Nitrogen Heterocyclic Power Systems
by Yunqiu Li and Qiyao Yu
Energies 2025, 18(7), 1609; https://doi.org/10.3390/en18071609 - 24 Mar 2025
Viewed by 501
Abstract
The innovation of energy storage technology and its solutions for energetic materials is an important direction in the current energy technology field. Hence, series of tetrazole-based ultra-high-energy-density high-nitrogen heterocyclic power compounds were designed and their energy characteristics and safety performances were evaluated by [...] Read more.
The innovation of energy storage technology and its solutions for energetic materials is an important direction in the current energy technology field. Hence, series of tetrazole-based ultra-high-energy-density high-nitrogen heterocyclic power compounds were designed and their energy characteristics and safety performances were evaluated by density functional theory (DFT). The results indicate that the type, number, and position of substituents have a significant effect on the comprehensive performance of these compounds. Research on electronic features shows that mono-substituents on the N atom connecting two tetrazole rings, substituents with more H atoms on the tetrazole ring, and less energetic substituents are beneficial for the stability of compounds. The discussion on energy characteristics and safety performance indicates that compounds B1(N-(1-nitro-1H-tetrazol-5-yl)-N-(1H-tetrazol-5-yl)nitramide), B7(N’-(1-nitro-1H-tetrazol-5-yl)-N’-(1H-tetrazol-5-yl)nitric hydrazide), B8(N-(1-(nitroamino)-1H-tetrazol-5-yl)-N-(1H-tetrazol-5-yl)nitramide), C1(5,5′-(hydrazine-1,1-diyl)bis(1-nitro-1H-tetrazole)), C4(N,N-bis(1-nitro-1H-tetrazol-5-yl)nitramide), and C6(N-(1-amino-1H-tetrazol-5-yl)-N-(1-nitro-1H-tetrazol-5-yl)nitramide) possess outstanding comprehensive performance concerning density, heat of formation, detonation heat, detonation velocity and pressure, oxygen balance, and impact sensitivity, and can be screened as candidates for high-energy-density compounds. The results are expected to provide new solutions for the innovation and progress of energy storage technologies in the energetic materials field. Full article
(This article belongs to the Special Issue Advancements in Energy Storage Technologies)
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14 pages, 7114 KiB  
Article
Preparation of Ultrafine Spherical Al-Mg Alloy and Its Energy Release Characteristics in Explosives
by Junhui Liu, Jie Yao, Zichao Wang, Wei Liu, Jianxin Nie and Shi Yan
Metals 2025, 15(2), 202; https://doi.org/10.3390/met15020202 - 14 Feb 2025
Viewed by 975
Abstract
The substitution of aluminum powder with highly reactive ultrafine aluminum-based metal fuels has a significant impact on the energy release of aluminum-containing energetic materials because of their excellent energy density and combustion performances. A series of ultrafine spherical Al-Mg alloy fuels with different [...] Read more.
The substitution of aluminum powder with highly reactive ultrafine aluminum-based metal fuels has a significant impact on the energy release of aluminum-containing energetic materials because of their excellent energy density and combustion performances. A series of ultrafine spherical Al-Mg alloy fuels with different contents of magnesium were prepared by close-coupled gas atomization technology. The properties of Al-Mg alloy powders of 13~15 μm were tested by SEM, TG-DSC, and laser ignition experiments. Results show that alloying with magnesium can significantly enhance thermal oxidation and combustion performance, leading to more oxidation weight gains and higher combustion heat release. HMX-based castable explosives with the same content of Al and the novel Al-Mg alloy were made and tested. Results show that the detonation performances of HMX/Al-Mg alloy/HTPB are better than HMX/Al/HTPB. Compared to the HMX/Al/HTPB explosive, the detonation heat of HMX/ Al-Mg alloy/HTPB was increased by 200 kJ/kg, the energy release efficiency was enhanced from 80.55% to 83.19%, the detonation velocity was increased by 114 m/s, and the shock wave overpressure at 5 m was increased by 83%. This research provides a new type of composite metal fuel for improving the combustion performance of Al powder. Full article
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16 pages, 3976 KiB  
Article
Influence of Augmentation Compositions and Confinement Layers on Flyer Velocity in Laser Impact Welding
by Mohammed Abdelmaola, Brian Thurston, Boyd Panton, Anupam Vivek and Glenn Daehn
Metals 2025, 15(2), 190; https://doi.org/10.3390/met15020190 - 12 Feb 2025
Viewed by 855
Abstract
Small-scale impact welding may have several advantages over rivets: the strength can be higher, it can be applied right at the edges in lap joints, and it can be lighter and more easily installed if simple systems can be developed. Laser Impact Welding [...] Read more.
Small-scale impact welding may have several advantages over rivets: the strength can be higher, it can be applied right at the edges in lap joints, and it can be lighter and more easily installed if simple systems can be developed. Laser Impact Welding (LIW) is compact and simple, adapting the technologies of laser shock peening. It is limited in terms of the energy that can be delivered to the joint. Augmented Laser Impact Welding (ALIW) complements optical energy with a small volume of an exothermic detonable compound and has been shown to be an effective welding approach. The scope of this study is extended to build upon previous work by investigating varied augmentation chemistries and confinement layers, specifically borosilicate glass, sapphire, and water. The evaluation of these compositions involved the use of two aluminum alloys: Al 2024 and Al 6061. Photonic Doppler Velocimetry (PDV) was utilized to measure the flyer velocity and assess the detonation energy. The findings indicated that adding micro-air bubbles (GPN-3 scenario) to the original GPN-1 enhanced the flyer velocity by improving the sensitivity, which promoted gas release during detonation. Hence, employing 1 mm thick Al 2024 as a flyer with GPN-3 enhances the flyer velocity by 36.4% in comparison to GPN-1, thereby improving the feasibility of using 1 mm thick material as a flyer and ensuring a successful welded joint with the thickest flyer ever welded with laser impact welding. When comparing the confinement layers, sapphire provided slightly lower flyer velocities compared to borosilicate glass. However, due to its higher resistance to damage and fracture, sapphire is likely more suitable for industrial applications from an economic perspective. Furthermore, the lap shear tests and microstructural evaluations confirmed that GPN-3 provided higher detonation energy, as emphasized by the tendency of the interfacial waves to have a higher amplitude than the less pronounced waves of the original GPN-1. Consequently, this approach demonstrates the key characteristics of a practical process, being simple, cost-effective, and efficient. Full article
(This article belongs to the Special Issue Advanced Metal Welding and Joining Technologies—2nd Edition)
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14 pages, 4284 KiB  
Article
Deriving High-Energy-Density Polymeric Nitrogen N10 from the Host–Guest ArN10 Compound
by Lulu Liu, Jiacheng Qi, Dinghui Wang, Jie Yuan, Difen Shi, Zhigang Xiong, Ting Ye, Yubei Cai and Lei Zhang
Nanomaterials 2025, 15(3), 249; https://doi.org/10.3390/nano15030249 - 6 Feb 2025
Viewed by 1029
Abstract
Discovering stable polymeric nitrogen phases and exploring their properties are crucial for energy storage and conversion, garnering significant attention. In this study, we investigate the formation possibility of a stable compound between Ar and N2 through ab initio calculations under low-pressure conditions [...] Read more.
Discovering stable polymeric nitrogen phases and exploring their properties are crucial for energy storage and conversion, garnering significant attention. In this study, we investigate the formation possibility of a stable compound between Ar and N2 through ab initio calculations under low-pressure conditions (0–100 GPa). The novel super nitride, Imm2 ArN10, is designed to demonstrate robust thermodynamic stability under high pressures (91 GPa) and showcase the unique host–guest structure, in which guest atoms (Ar) are trapped inside the host polymeric N10. Significantly, given the weak interaction between Ar and N atoms and a channel parallel to the c-crystallographic axis in ArN10, we propose a novel method to stabilize the previously unknown polymeric nitrogen structure, Imm2-N10, by removing the guest argon atoms from the natural channels of ArN10. Imm2 ArN10 and N10 are thermodynamically and dynamically stable, with energy densities of 9.1 kJ g−1 and 12.3 kJ g−1, respectively—more than twice that of TNT. Additionally, ArN10 and N10 stand out as leading green energetic materials, boasting a superior explosion velocity of 17.56 km s−1 and a detonation pressure of 1712 kbar, surpassing that of TNT. These findings significantly impact on the creation of pure nitrogen frameworks through chemical reactions involving inert elements under high pressure. Full article
(This article belongs to the Special Issue The Interaction of Electron Phenomena on the Mesoscopic Scale)
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