Detonation Performance Research Articles

Bifuruzan skeleton: developing new high-energy and high-density energetic materials.

High-energy density materials (HEDMs) are integral to modern society and are in high demand. Consequently, the design and synthesis of energetic material molecules have garnered significant research interest. This study focuses on the furazan ring system as a core for developing superior HEDMs. We employed density functional theory (DFT) to assess the properties of 27 novel energetic compounds, including their geometries, densities, enthalpies of formation, detonation velocities, detonation pressures, and molecular orbital energies (HOMO-LUMO). The computation of detonation velocity and detonation pressure was based on theoretical density and enthalpy of formation. The findings revealed that incorporating energetic groups into the furazan framework, linked by sec-ammonia bridge (-NH-), enhances both the detonation performance and oxygen content of the materials. This enhancement guides the future synthetic endeavors aimed at creating advanced HEDMs. DFT has been employed to investigate the detonation performance and stability of energetic materials. Molecular optimization and performance metrics were all calculated using the DFT-B3LYP method with a 6-311 + G* basis set. The optimization and volume calculations were performed using the Gaussian 09 package. The electrostatic potential energy was computed using Multiwfn software. The impact sensitivity of the designed molecules was calculated using the heat of detonation model.

Employing the Trifluoromethyl Group on a 5/5 Fused Triazolo[4,3-b][1,2,4]triazole Backbone: A Viable Strategy for Attaining Balanced Energetics.

In this study, we synthesized trifluoromethyl-substituted bis-triazole nitrogen-rich compounds (3-5) using a simple, cost-effective method. The newly made compounds were characterized using NMR, IR, elemental analysis, TGA-DSC, and single-crystal X-ray diffraction (for compounds 3 and 4). They demonstrated high density (1.82-1.92 g cm-3), moderate detonation performance (7567-7905 m s-1), good thermal stability (146-215 °C), and low sensitivity to impact (40 J) and friction (360 N), offering high potential nature as a cationic component in energetic salts, defense, and civilian applications.

Design and characterization of high-performance energetic hydrogels with enhanced mechanical and explosive properties

Polymeric hydrogels, known for their excellent mechanical properties and pre-cross-linking flowability, provide a promising solution for recycling waste propellants, ensuring safety and maintaining explosive performance. This study developed a double cross-linked network energetic hydrogel that effectively combines mechanical strength with explosive capabilities. Using a Ford 4 Cup, temperature data logger, universal testing machine, and detonation performance tests, we examined the impacts of kinematic viscosity, cross-linking time, compressive strength, and explosive properties. The optimal kinematic viscosity for stabilizing hollow glass microspheres (GM) was found to be 129.7 mm2/s. Cross-linking time was negatively correlated with initiator, catalyst levels, and reaction temperature, but positively correlated with retarder content. Compressive strength increased with acrylamide (AM) content and showed an initial rise before decreasing with N,N′-methylenebisacrylamide (MBAA) content and reaction temperature. The maximum compressive strength was achieved with 5% MBAA (of AM mass fraction) at 40 °C. Detonation velocity and steel plate damage decreased with increasing AM content and initially increased then decreased with GM content. A balance of mechanical and explosive properties was achieved with 6% AM and 4% GM, resulting in a detonation velocity of 4536 m/s. This hydrogel shows significant potential for waste munitions management.

3, 4-Bis (3-nitrofurazan-4-yl) furoxan (DNTF) and 4-methoxy-1-methyl-3, 5-dinitro-1H-pyrazole (DMDNP) based molten carrier with high energy and low sensitivity: eutectic design and desensitization effect

Utilizing insensitive explosives to form a eutectic with 3, 4-bis (3-nitrofurazan-4-yl) furoxan (DNTF) proved to be an effective method for reducing its sensitivity and melting point. In this study, the interaction between DNTF and 4-methoxy-1-methyl-3, 5-dinitro-1H-pyrazole (DMDNP) was simulated using the interaction region indicator (IRI), revealing that the intermolecular forces in the mixture are stronger than those of the individual components. Co-molten mixtures of DNTF-DMDNP with varying compositions were prepared through electrostatic spraying technology, and a binary phase diagram was established using differential scanning calorimetry (DSC). The experimentally extrapolated molar ratio of the DNTF-DMDNP eutectic was determined to be 48.7/51.3, with a eutectic point at approximately 338.2K. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) tests confirmed that no chemical reactions or crystal transformations occurred during the preparation of the eutectic. The thermal decomposition temperatures at different heating rates and apparent activation energy of the eutectic fell within the range between those of DNTF and DMDNP. Addition of even just 10% DMDNP significantly reduced mechanical sensitivity in co-molten mixtures, resulting in a rapid decrease from 100% to 12% friction sensitivity. The detonation velocity of the DNTF-DMDNP eutectic measured at 8.47kms-1 only experienced a slight decrease by about 0.78kms-1 (8.4%) compared to pure DNTF, indicating efficient desensitization by incorporating DMDNP with minimal energy loss potentiality. Furthermore, adjusting composition allowed for control over detonation performance and sensitivity in melt-cast explosives composed of DNTF-DMDNP.

Measurement of plasma characteristic parameters of copper foil explosion using interferometry

The accurate testing of plasma temperature and electron density and shock wave pressure during an electroburst in a copper foil transducer is critical for the characterization of the detonation performance of its elements. In this paper, the sequence of interferograms during the detonation of a copper foil transducer is captured at a frame rate of 3×106fps in conjunction with Mach–Zehnder interferometry and high-speed photography, and the results clearly demonstrate the propagation of the shock wave wavefront and plasma. The phase differences disturbed by plasma are extracted using the Fourier transform method, and the refractive index distributions are reconstructed with the Abel algorithm. Subsequently, based on the refractive index models of the shock wave and plasma, the shock wave pressure and plasma temperature and electron density are partitioned and reconstructed. Results show that the maximum shock wave pressure in the detonation of the copper foil transducer element is 1.297 atm, the maximum plasma temperature is 16,280 K, and the maximum plasma electron density is 2.134×1017cm−3. This study provides a theoretical and technical foundation for the detonation performance testing of pyrotechnic energy-conversion components.

Synthesis of 4-Amino-5-nitro-7H-pyrazolo[3,4-d][1,2,3]triazine-2-oxide and Its Heat-Resistant Derivatives.

4-Amino-5-nitro-7H-pyrazolo[3,4-d][1,2,3]triazine-2-oxide (PTO) is synthesized via one step in this study. Subsequently, 4,7-diamino-5-nitro-pyrazolo[3,4-d][1,2,3]triazine-2-oxide (APTO), 4-oxo-5-nitro-7H-pyrazolo[3,4-d][1,2,3]triazine-2-oxide (OPTO), and several heat-resistant salts are synthesized through local structural modifications on PTO. Comparison of thermal stability between PTO and APTO indicates that while the amino group has a negative impact on the thermal stability of APTO, it enhances the detonation performance of APTO and effectively reduces its mechanical sensitivity. Our findings provide a practical new approach for constructing energetic materials with excellent stability.

Unleashing Ultrahigh Detonation Performance with Oxalyldihydrazinium Dication-Based Energetic Salts

Unleashing Ultrahigh Detonation Performance with Oxalyldihydrazinium Dication-Based Energetic Salts

Impact of nitromethane additive on ANFO performance

The article presents an evaluation of the detonation performance of a nitromethane-ammonium nitrate fuel oil energetic material. The brisance and relative strength of this material were assessed using the Hess and Trauzl methods. Both methods confirmed that the shattering effect and relative work increase in a polynomial manner with the increasing content of nitromethane. A significant enhancement in detonation parameters was observed with up to 9% nitromethane addition. The results from the Trauzl and Hess tests indicated that at 9% nitromethane content, the average cavity expansion and brisance were 371 cm3 and 10.01 mm, respectively. The improved detonation performance is attributed to the introduction of additional nitro groups from nitromethane, replacing fuel oil, as well as the increased density of the energetic material.

The molecular structure, electronic properties, and decomposition mechanism of FOX-7 under external electric field were calculated based on density functional theory.

Based on the density functional theory (DFT), we analyzed the changes of the FOX-7 molecule under external electric field (EEF) from multiple perspectives, including molecular structure, electronic structure, decomposition mechanism, frontier molecular orbitals (FMOs), and density of states (DOS). The results revealed that as the intensity of the positive EEF increased, the detonation performance of the FOX-7 molecule was significantly enhanced, while its thermal stability was also improved. This discovery challenges the traditional concept that explosives are inherently dangerous under external electric fields and provides new insights for research in related fields. To further explore the impact of EEF on the thermal stability of FOX-7, we conducted a thorough analysis of the mechanism by which EEF affects the decomposition process. Our findings indicate that applying a positive EEF significantly increases the energy required to overcome intramolecular hydrogen transfer and C-NO2 bond rupture, while having a relatively minor effect on the nitro isomerization process. This observation further demonstrates that the appropriate application of a positive EEF can enhance the detonation performance of FOX-7 without compromising its thermal stability. Further research revealed that as the intensity of the positive EEF increased, the electronegativity of the nitro group gradually enhanced, leading to an increase in the electronegativity of the oxygen atoms within it. This made the oxygen atoms more prone to participating in chemical reactions. This phenomenon also explains why the energy barrier required for nitro isomerization in FOX-7 gradually decreases as the intensity of the positive EEF increases. Based on the density functional theory (DFT), the structural optimizations were performed both under applied EEF and without EEF at the B3LYP/6-311G (d, p) level. All optimized results were converged and exhibited no imaginary frequencies. Based on the optimized structures, single-point energy calculations were further conducted at the B3LYP/def2-TZVPP level. Subsequently, analyses of molecular structure, electronic structure, decomposition mechanism, frontier molecular orbitals, and density of states were carried out.

Resistive Heating and Thermal Decomposition of an Additively Manufacturable Electrically Conductive Explosive

AbstractThe ability to transmit electrical signals through high explosive charges without using dense metal conductors could enable continuous monitoring of explosive charges with internally embedded sensors. With the sensor materials themselves being energetic, the impact on the intended detonation performance of the charge can be minimized. Embedded sensors enable real time, in‐situ measurements of conditions relevant to ageing assessments. Additionally, dynamic material property sensing can provide detonation performance data, enabling measurement of dynamic shock position. One proposed method to allow for electronic signal transfer through high explosives is to use electrically conductive explosive composites consisting of an electrically conductive polymer binder mixed with high explosive crystals. These conductive energetic pathways also serve as independently reactive elements and can provide additional functionality via dynamic sensor removal through resistive heating and subsequent decomposition. This work discusses the resistive heating of a previously developed, poly (3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) based, electrically conductive extrudable explosive composite. Experimental samples of the conductive explosive material were subjected to a range of direct current applications and the resulting heating and decomposition of the material is discussed.

Machine learning approaches for predicting impact sensitivity and detonation performances of energetic materials

Excellent detonation performances and low sensitivity are prerequisites for the deployment of energetic materials. Exploring the underlying factors that affect impact sensitivity and detonation performances as well as exploring how to obtain materials with desired properties remains a long-term challenge. Machine learning with its ability to solve complex tasks and perform robust data processing can reveal the relationship between performance and descriptive indicators, potentially accelerating the development process of energetic materials. In this background, impact sensitivity, detonation performances, and 28 physicochemical parameters for 222 energetic materials from density functional theory calculations and published literature were sorted out. Four machine learning algorithms were employed to predict various properties of energetic materials, including impact sensitivity, detonation velocity, detonation pressure, and Gurney energy. Analysis of Pearson coefficients and feature importance showed that the heat of explosion, oxygen balance, decomposition products, and HOMO energy levels have a strong correlation with the impact sensitivity of energetic materials. Oxygen balance, decomposition products, and density have a strong correlation with detonation performances. Utilizing impact sensitivity of 2,3,4-trinitrotoluene and the detonation performances of 2,4,6-trinitrobenzene-1,3,5-triamine as the benchmark, the analysis of feature importance rankings and statistical data revealed the optimal range of key features balancing impact sensitivity and detonation performances: oxygen balance values should be between −40% and −30%, density should range from 1.66 to 1.72 g/cm3, HOMO energy levels should be between −6.34 and −6.31 eV, and lipophilicity should be between −1.0 and 0.1, 4.49 and 5.59. These findings not only offer important insights into the impact sensitivity and detonation performances of energetic materials, but also provide a theoretical guidance paradigm for the design and development of new energetic materials with optimal detonation performances and reduced sensitivity.

Effect of cavity depth on air-breathing rotating detonation engine fueled by liquid kerosene

In our recent experimental investigation, the feasibility of a liquid-kerosene-fueled air-breathing/ramjet rotating detonation engine featuring a cavity-based annular combustor has been experimentally demonstrated. Achieving stable operation and organized detonation combustion within the rotating detonation combustor presents significant challenges that demand further investigation. Thus, this study aimed to deepen our understanding of the optimal geometrical configuration of a cavity-based annular combustor operating in air-breathing mode. Numerous experiments were conducted to evaluate the impact of varying cavity depths on combustion performance under a supersonic incoming flow with a total temperature of 860 K. The findings indicate that adequate cavity depth is essential for the generation of kerosene-fueled rotating detonation waves in air-breathing mode. Notably, a kerosene–air rotating detonation wave was achieved in combustors with cavity depths ranging from 10 to 30 mm while maintaining a supersonic heated air mass flow rate of approximately 1000 g/s and a minimum equivalence ratio of 0.77. However, at a cavity depth of 10 mm, both the propagation velocity and peak pressure of the rotating detonation waves were significantly lower compared to those at 20 and 30 mm, thereby suggesting that the depth of 10 mm may require optimization. Additionally, optical observations revealed that the detonation reaction zone was located further from the combustor head as cavity depth increased. This indicates that deeper cavity depths allow for longer mixing and preheating times of the combustible mixture before detonation, thereby enhancing detonation performance. This study clarifies how cavity depth influences liquid-fueled rotating detonation and provides guidelines for designing cavity-based annular combustors in air-breathing rotating detonation engines.

Revealing the Response of Structure and Decomposition Behaviors of 1, 1′‐Azobis‐1, 2, 3‐Triazole to Pressure: A Theoretical Study

ABSTRACT1, 1′‐azobis‐1, 2, 3‐triazole (C4H4N8, N8) is a novel nitrogen‐rich energetic material with excellent detonation performance, which has received widespread interest. Inspired by recent theories and experiments, the dependence of structural, vibrational, and electronic properties on high pressure up to 10 GPa was systematically investigated using periodic DFT calculations. It was found that the optimized structure belonged to the cis‐N8 structure through comparing the theoretical IR with experimental IR spectra. The third‐order Birch–Murnaghan equation of state for N8 was obtained up to 10 GPa, where the bulk modulus and its pressure derivative were 10.91 GPa and 7.689, respectively. More importantly, the pressure dependence of Laplacian bond order indicated that the five‐membered ring opening was the first step in the decomposition process, and that high pressure could inhibit the decomposition process of N8 due to the reinforcement of non‐covalent interactions. The present work could deepen the understanding of the energetic materials N8 under high pressure, and is of great significance to the blasting and detonation applications of N8.

Preparation of spherical DAOAF with micro-nano structure by emulsion method: To improve short-pulse initiation performance

In order to take into account the advantages of good processing performance of micron 3,3′-diamino-4,4′-azoxyfurazan(DAOAF) and high sensitivity of short-pulse initiation of nano DAOAF, Spherical DAOAF products with nano-microstructure were prepared by oil-in-oil emulsion method. The laser-induced air shock wave detonation performance, mechanical sensitivity and short-pulse initiation sensitivity of raw DAOAF and spherical DAOAF were tested and compared. The results showed that the optimum process conditions of emulsion stability were as follows: using Tween-80 as the surfactant at a concentration of 0.3 g·mL−1, a solvent-non-solvent volume ratio of 1:3, and emulsion standing time less than 10 minutes. Compared to the raw DAOAF, the crystal structure of DAOAF sample prepared by emulsion method did not change, only the morphology changed. The DAOAF sample prepared by emulsion method is spherical, and the surface is self-assembled by nanorod-like DAOAF, the particle size distribution is uniform and the dispersion is good. The thermal decomposition peak temperature of spherical DAOAF did not change significantly, but the activation energy of thermal decomposition decreased by 30.07 kJ·mol−1, the characteristic velocities of the laser-induced micro-explosion shock waves increased 12.4 %, the 50 % short-pulse initiation current of the impactor decreased from 3.8 kA to 2.3 kA, and the mechanical sensitivity of DAOAF showed no significant change before and after spherical transformation.

Theoretical exploration of energetic molecular design strategy: functionalization of C or N and structural selection of imidazole or pyrazole.

In researching energetic materials with high energy density, it is an effective method to introduce explosophoric groups. In this study, four series of energetic compounds were designed by functionalizing with C- or N-, introducing energetic groups -CH(NO2)2, -CF(NO2)2, -C(NO2)2(NF2), -C(NO2)3, and-CH(NF2)2 into imidazole and pyrazole structures. Density functional theory was employed to optimize the structure of the target compound and subsequently to predict and evaluate its performance based on this. Meanwhile, the sensitivity of the compounds was predicted based on their electrostatic potential analysis. Following analysis of the geometric structure, detonation performance, and sensitivity of the compounds, three factors were discussed: energetic groups, functionalization methods, and skeleton structure differences. The results indicate that C-functionalization has advantages only in density, but N-functionalization is better in thermal stability, heat of formation, and sensitivity. Meanwhile, the data shows that imidazole-based compounds exhibited greater density and detonation performance in the target compounds designed within this study, while pyrazoles have a higher heat of formation and chemical stability. By analyzing the design strategy of C- or N-functionalization of novel high-energy groups on energetic imidazole or pyrazole rings and selecting a more suitable molecular construction strategy, this study provides a theoretical approach for the development of new energetic materials with excellent performance. Gaussian 09 and Multiwfn 3.8 packages are the software used for calculation, and the electrostatic potentials were depicted using the VMD program. In this study, the imidazole and pyrazole derivatives were optimized at the B3PW91/6-311G (d, p) level to acquire the relevant data for the compounds.

Energetic Salts of Cubane-1,4-Dimethylnitrocarbamate.

Several salts of cubane-1,4-dimethylnitrocarbamate (CMNC) were synthesized. The divalent CMNC is deprotonated by alkaline, alkaline earth metal, and nonmetal bases to form the corresponding salts. The compounds were characterized and analyzed by multinuclear NMR and IR spectroscopy, mass spectrometry, elemental analysis, single crystal X-ray, and thermoanalytical techniques. The energies of formation for the salts were calculated using Gaussian. Detonation performances were calculated with the Explo5 (V6.03) computer code. The sensitivities toward impact and friction were determined and compared to the neutral CMNC.

The Effects of Material‐Filled Voids on Detonation Wave Shape in Rubberized RDX Explosives

AbstractThe sensitivity of explosives is affected by inhomogeneities within the material. This is evident in the increased shock sensitivity of explosives with slightly lower densities resulting from an increased number of hotspots. The influence of hotspots on explosive initiation has been well studied; however, few studies have been conducted on the effect of intermediate‐sized voids (0.1–10 mm) on a propagating detonation wave. Cylindrical voids filled with air have been studied for diameters ranging from 0.3 mm to 0.8 mm for both 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane (HMX) and 1,3,5‐trinitro‐1,3,5‐triazinane (RDX)‐based rubberized explosives. Continuing the investigation into single cylindrical voids, this study examined the effects of 0.5 mm diameter voids filled with different inert cylindrical metals on the detonation wave shape for an RDX‐based rubberized explosive. The metals selected for experiments were 1066 aluminum, brass, copper, and tungsten. The propagation of the detonation wave was captured using a digital streak camera. Experimental results showed that the extent of detonation wave shaping was closely tied to the density differential between the bulk explosive and metal insert. Forty‐four different filler materials, including non‐metals, were simulated using a hydrodynamic code to further analyze material inclusion effects. The main factors hypothesized to be of interest were bulk sound speed, shock impedance, and filler material density. We found that the local detonation delay could be correlated fairly well to a ratio of bulk sound speed and density. Understanding the influence of material inclusions on detonation performance and wave shape allows for tailoring of detonations.

The Study on Synthesis and Characterization of Insensitive Energetic Materials Based on 5‐(5‐Nitro‐1H‐1,2,4‐Triazol‐3‐yl)‐1H‐Tetrazole

ABSTRACTThe design and synthesis of insensitive energetic materials are a necessary and challenging work. The synthesis of novel nitrogen‐rich salts based on 5‐(5‐Nitro‐1H‐1,2,4‐triazol‐3‐yl)‐1H‐tetrazole (H2NTT) has been presented. Structural characterization of these two salts was accomplished by utilizing NMR, MS, IR spectroscopy, and X‐ray diffraction. The standard heats of formation were calculated, and the differential scanning calorimetry (DSC) and sensitivity test were carried out. Their detonation performances were estimated by EXPLO 5 program. These newly synthesized salts showed highly positive heat of formation and low sensitivity. It is noteworthy that the diaminoguanidine salt b exhibited good detonation performance superior to traditional explosive TNT (Trinitrotoluene), making it a prospective candidate for insensitive energetic material.

Dicationic Methylene‐Bridged Bis(1,2,4‐Triazolium): Construction of Thermally Stable and Insensitive Energetic Salts

AbstractA thermally stable and high nitrogen content energetic cation N,N'‐methylene‐bis(3,4,5‐triamino‐1,2,4‐triazolium) (MTAT, N = 69.38%, ΔHf = 1959.07 kJ/mol) has been used as a building block for preparing a new family of energetic salts. Compounds 1 and 4 were characterized by infrared and multinuclear NMR spectra. Structural confirmation of four salts (1–4) was supported by single‐crystal X‐ray diffraction. Theoretical calculations were performed to calculate the heats of formation and detonation performance using Gaussian 09 and EXPLO5 v6.05 programs, respectively. The impact and friction sensitivity of COMPOUNDS 1 and 2 were measured using BAM standards. Based on experimental and theoretical results, two energetic salts (1 and 3) featuring the novel cation framework MTAT exhibited favorable densities ranging from 1.751 to 1.809 g cm−3 at 298 K, excellent thermal stability (Td: 250–257 °C), acceptable detonation performance (D: 8001–8097 m s−1, P: 23.3–26.7 GPa), and good impact and friction sensitivity (IS: 18–40 J, FS: 240–360 N).

Improving Friction Sensitivity of Molecular Perovskite Energetic Material DAP‐4 by Polymer Binders Coated

AbstractThe high detonation and thermostability of the molecular perovskite energetic material DAP‐4 attracted a lot of interest, but its high friction sensitivity hindered its applicability. It is critical to minimize the friction sensitivity of DAP‐4 for future applications. DAP‐4‐based composites with core‐shell structures coated by polymer binders were devised and manufactured in this study. DAP‐4 was discovered to be polymer binder compatible, and the thermal breakdown temperature remained constant at 380°C. The friction sensitivity of DAP‐4‐based core‐shell composites increased from 36 N (raw DAP‐4) to 60 N (DAP‐4@Estane‐5703, DAP‐4@F2602, and DAP‐4@F2311) when 10% polymer binders were added as shell‐structured layers. Furthermore, their theoretical detonation performance was calculated, and each sample demonstrated superior performance. Among them, the theoretical detonation velocity of DAP‐4@F2602 reached 8081 m/s, and the heat of detonation was 5.118 kJ/kg. This provided proof‐of‐concept work for increasing the mechanical safety of molecular perovskite energetic materials.