To accurately and quantitatively assess the safety of emulsion explosive-based permitted products used in underground coal mines, the effects of types and contents of typical flame inhibitors on the explosion fireball characteristics and blast overpressure parameters of emulsion explosives were studied by the air blast experiment combined with the two-colour pyrometer technology. The experimental results showed that KCl powders had the best flame inhibition effect on the emulsion explosives with equal mass of flame inhibitors, and the maximum average temperature and duration of its explosion fireball were 2003 K and 11.6 mu s, respectively, which were 18.2% and 60% lower than those of non-additive emulsion explosives. Compared with emulsion explosives containing NaCl powders, the average temperature of explosion fireball of emulsion explosives containing NH4Cl powders was lower, but the duration of explosion fireball and the peak pressure of shock wave were enhanced. Furthermore, with the increasing content of KCl powders in emulsion explosives, the flame inhibition effect was more intense but the intensity of detonation shock wave was lower. Therefore, to reduce the loss of shock wave peak pressure to the greatest extent, the addition content of KCl powder in emulsion explosives should be as low as possible under the condition that the flame inhibition performance meets the standard requirements. The research results will be help to further reveal the explosion fireball characteristics and energy release mechanisms of emulsion explosives containing flame inhibitors, and provide technical support for the formulation design and quantitative safety assessment of emulsion explosive-based permitted products used in underground coal mines.
To further improve the rheological properties of aluminum(Al)- containing methylcellulose (MC) ethanol gel propellants, it is essential to address the limitations of previous studies, including the poorly understood effects of the Al powder and the absence of applicable rheological models. In the present work, the effects of the Al powder content (0-25%), temperature (35-70 degrees C), and particle size (100 nm, 5 and 50 & micro;m) on the rheological behaviour of the gel were systematically investigated. Capillary rheometer tests were conducted to obtain the relationships between the shear rate and the apparent viscosity, as well as between the shear rate and the shear stress. These data were fitted using five rheological models: Ostwald-de Waele (power-law), Cross, Carreau, Bingham, and Herschel-Bulkley. The results showed that the gel exhibited typical pseudoplastic (shear-thinning) behaviour, with a non-Newtonian index n < 1. As the nano-Al mass fraction was increased from 10% to 25%, n decreased from 0.46 to 0.24, while the consistency coefficient K increased from 0.45 to 2.17 kPa & centerdot;s(n), indicating that appropriate Al loading enhanced the shear-thinning behaviour and strengthened the gel's network structure. At an Al content of 20%, increasing the temperature from 35 to 50 degrees C led to an increase in K from 0.64 to 2.67 kPa & centerdot;s(n). However, when the temperature exceeded 50 degrees C, structural degradation occurred because of excessive solvent evaporation. Therefore, the optimal formulation was determined to be 20% Al at 50 degrees C, under which the gel exhibited both high stability (residual mass after centrifugation >90%) and desirable rheological properties. Moreover, the apparent viscosity increased significantly as the Al particle size was decreased, from 440.5 Pa & centerdot;s at 50 & micro;m to 906.2 Pa & centerdot;s at 100 nm. The model fitting results indicated that the Herschel-Bulkley model (R & sup2; > 0.98) and the Ostwald-de Waele model (R & sup2; > 0.99) best described the rheological behaviour of the gel. A temperaturedependent correction model based on the Arrhenius equation was developed: eta = 3.55 & times;107 exp(-27.19/RT)& centerdot;gamma<^>(-0.5628-6.82 & times;10-4T). This model effectively predicted the apparent viscosity, eta, under varying temperatures and shear rates. This work provides the theoretical guidance and experimental support for the formulation design and process optimization of Al-containing gel propellants.
Water hammer is a transient hydraulic phenomenon caused by rapid changes in fluid velocity, generating significant pressure surges in fluid systems. These effects are particularly critical in installations handling volatile or pressure-sensitive media, where uncontrolled hydraulic shocks may compromise operational safety, system integrity, and component reliability. Experimental tests were conducted on a straight, two-meter test object that could be evacuated of gas, thereby establishing the initial conditions required for benchmarking the priming process. The experiments were complemented by theoretical analyses and numerical simulations performed in the EcosimPro environment using the specialized ESPSS toolbox, enabling the creation of a digital representation of the test rig and test object. The resulting pressure surges were compared to assess the accuracy of the prediction methods. The development of a reliable predictive method would significantly support the design process by reducing the need for costly and time-consuming experimental campaigns. The study concludes with a summary of the obtained results and an assessment of the feasibility of simulating and predicting water hammer phenomena. Furthermore, lessons learned for future research on hydrogen peroxide pressure surges are discussed, including recommendations for improving the repeatability of the experimental tests.
Accurate determination of the burn rate and pressure exponent, commonly expressed as the n-value, is critical for evaluating the ballistic performance of solid rocket propellants. These parameters are frequently obtained using subscale motors (SSMs); however, their estimation is often influenced by uncertainties associated with ignition transients, hump effects, Friedman-Curl effects, dimensional tolerances, and instrumentation-related errors. In the present study, an experimentally validated numerical model was employed to generate approximately 1,000 pressure-time (P-t) profiles covering a broad range of burn rates (5-35 mm/s), pressure indexes (0.2-0.6), and chamberpressures (3-35 MPa). Realistic uncertainty sources were systematically introduced into these profiles to assess their influence on the burn rate and n-value estimations. Two validated data-reduction algorithms, separately developed for progressive and neutral SSM configurations, were used to extract the ballistic parameters. The computed values were then compared with the prescribed input parameters to quantify the corresponding relative errors. The novelty of this work lies in the development of a large-scale simulation framework that incorporates multiple sources of practical uncertainty and enables a comparative assessment of error propagation in progressive and neutral SSMs, an aspect that has not been extensively addressed in the existing literature. The results show that progressive SSMs are considerably more sensitive to measurement uncertainties, whereas neutral SSMs demonstrate greater robustness and consistency. These findings provide useful guidance for improving the accuracy, precision, reliability and uncertainty of ballistic-property evaluation in future propellant development and motor-design studies.
Ammonium nitrate fuel oil (ANFO) compositions are widely used bulk industrial explosives in mining and civil engineering. Even though they are being replaced by the latest generation of emulsion explosives, some unique properties, such as a relatively simple production process, low price and very low impact sensitivity to stimuli, make them a good alternative to other explosives. However, a suitable primer should be used for the efficient initiation ofANFOs. Thus, three types of primers were studied in order to evaluate the effect of priming on the detonation development of ANFOs. Measurements were performed using the continuous resistance wire technique. The development of the detonation until it reached the stable detonation velocity has been analysed and discussed. An analysis confirmed that, depending on the type of primer used, a stable detonation velocity of an ANFO is achieved at different distances from the primer. The results have also proved that there is no significant influence of the type of primer used on the stable velocity of detonation for the tested diameter. An analysis confirmed that, depending on the type of primer used, a stable detonation velocity of ANFO is achieved at different distances from the primer.
Ammonium perchlorate (AP), the main oxidizer for solid propellants, results in white smoke (HCl); which could induce acidic rain and could damage fertile soil. A chlorine-free oxidizer is highly valued for solid propellants. Ammonium nitrate (AN) emerges as a promising green oxidizer; however it exhibits low performance (i.e. specific impulse). The present work describes the synthesis of copper chromite nanoparticles (NPs) of 45 nm. Copper chromite NPs were synthesized through hydrothermal synthesis; the developed nanocatalyst was then integrated into an AN matrix. While virgin AN demonstrated a strong endothermic decomposition of +1707 J/g, catalyzedAN demonstrated a superior exothermic decomposition, with an enthalpy of -1492 J/g. A solid propellant formulation based on AN and copper chromite (CuCr2O4) was optimized using the Institute for Chemical Technology (ICT) thermodynamic code via partial replacement of AP with AN. AN (30 wt.%) was found to decrease the smoke signature by 54.4%, with a minimum decrease in specific impulse. The solid propellant formulation was developed via mixing and vacuum casting. The ballistic performance was assessed using a small-scale ballistic evaluation rocket motor. The AN-based formulation demonstrated a stable combustion process with a slight decrease in the characteristic exhaust velocity and total pressure impulse of 4% and 4.8%, respectively. It may be concluded that a solid propellant with customized ballistic performance and low smoke signature has been optimized and developed.
Traditional manufacturing of solid rocket motor grains is constrained by challenges associated with the mechanical removal of the casting core. This study investigates a hybrid method that combines conventional propellant casting with 3D-printed soluble cores to overcome these manufacturing limitations and enable greater design freedom. Moulds were fabricated using FDM from materials including BVOH, HIPS, and ABS. After casting a propellant, these moulds were dissolved using compatible solvents such as water, limonene, or acetone. The ballistic properties of the resulting propellant grains, including burn rate and ignition delay, were evaluated in a laboratory-scale rocket motor test stand. The choice of solvent proved critical to propellant performance. While organic solvents resulted in reliable ignition, water immersion caused ignition failures, likely due to the leaching of the water-soluble oxidiser. A comparison revealed that grains produced via the soluble core method exhibited a slightly higher burn rate than conventionally manufactured reference samples across a pressure range of 20 to 70 bar. The 3D-printed soluble core method is a promising technique for fabricating complex SRM grains. However, its success is critically dependent on the careful selection of a compatible material-solvent propellant system to prevent chemical interactions that degrade ballistic performance, particularly ignition reliability.
Spherical propellants are widely used in handgun ammunition due to their favorable ballistic and manufacturing properties. Enhancing their energy content is a key objective for improving bullet velocity and overall performance. In this study, a high-energy spherical propellant was developed via an emulsion-based method, optimizing the NM/EAc (nitromass/ethyl acetate) ratio and solvent removal conditions. The optimal formulation was identified at an NM/EAc ratio of 1/2.5 with 50% solvent removal, resulting in spherical particles primarily in the 0.125-0.315 mm range (80 wt.%). The final product exhibited a combustion heat of approximately 998 cal/g, representing a 9.07% increase over conventional spherical propellants. Ballistic testing with 7.62x25 mm Tokarev cartridges showed that coating the propellant with 2% ethylcentralite improved bullet velocity by 8.9%. Importantly, the enhanced energy content did not compromise key physical characteristics such as specific gravity, bulk density, or chemical stability. These results demonstrate that careful adjustment of formulation parameters can lead to higher-performance spherical propellants suitable for small-caliber applications.
Explosive hazards-from legacy unexploded ordnance (UXO) to rapidly evolving improvised explosive devices (IEDs)-pose lasting risks to people and ecosystems. Beyond blast effects, open-burn/open-detonate (OBOD) practices release toxic metals (Pb, depleted U, W) and energetic residues (e.g. TNT, RDX, HMX) that persist in soils, sediments, and groundwater. This review benchmarks six widely used Explosive Ordnance Disposal (EOD) data resources: - TURPIN, - Cat-UXO, - EODVOID, - the NATO Ammunition Data Base (NADB), - IMSMA, and-ORDATA, against five criteria: - completeness, - update latency, - data-quality assurance, - environmental fields, and-accessibility. We synthesize empirical measurements around UXO sites and compare life-cycle evidence for OBOD versus contained detonation/burn and hydro-abrasive cutting. While the databases excel at imagery and identification, environmental metadata, quality assurance/quality control (QA/QC) provenance, and access remain uneven, limiting artificial intelligence (AI)-assisted analysis and coordinated remediation. Case studies consistently show metals and energetics above screening benchmarks, underscoring the need for standardized contamination fields (matrix, depth, analyte, method, units, detection limits). We propose a roadmap-harmonized exchange schemas, audit trails, and integration of real-time sensors withAI hotspot prediction-to evolve EOD databases into sustainability-oriented decision-support systems. A unified data ecosystem can advance cleaner water and seas, healthier soils, and safer communities, aligning with the 2023 UN Environment Assembly's call to address conflict-related pollution.
To investigate the effect of high-energy nitramine explosives on the performance of mixed ester-nitramine propellants, a closed bomb apparatus and mechanical property testing instruments were used. The combustion and mechanical properties of mixed ester-nitramine propellants containing nitramine explosives and different particle sizes of RDX, as well as three different highenergy formulations incorporating RDX (propellants ZTH-1 and ZTH-2), HMX (propellant ZTA), and CL-20 (propellant ZTC), were evaluated. The results indicate that the burning rate (U) of mixed ester-nitramine propellants varies with the RDX particle size, with larger RDX particles leading to a higher U. The U values of the three different types of nitramine propellant samples follows the order: U(ZTC)> U(ZTH-2)> U(ZTH-1)> U(ZTA). For the three different types of nitramine propellant samples, the ZTH-2 propellant exhibited the lowest pressure exponent, while the ZTC propellant had the highest pressure exponent. The impact strength followed the order: alpha(kappa)(ZTH-2) > alpha(kappa)(ZTA) > alpha(kappa)(ZTH-1) > alpha(kappa)(ZTC). The ranking of the low-temperature drop-weight impact strengths at-40 degrees C was as follows: [ZTA] > [ZTH-2] > [ZTH-1] > [ZTC].
Nitrogen-rich compounds have been widely used in pyrotechnic composition and gas generators due to their high gas yield, enthalpy of formation, and environmental friendliness. However, when various nitrogen-rich compounds are used in combination with other energetic materials, adverse phenomena such as reduced thermal stability occur in the mixture. Therefore, GAP-ETPE (GAP-based energetic thermoplastic polyurethane elastomer) is selected as the coating material to enhance the thermal stability of the incompatible energetic compounds, 5-AT (5-amino-tetrazole) and NC (nitrocellulose). A relatively complete ETPE coating layer was successfully formed on the surface of 5-AT particles by solvent evaporation method. The DSC (Differential scanning calorimeter) and VST (Vacuum stability test) test results show that when 5-AT@ETPE is mixed with NC, the variation in decomposition temperature is reduced by 4.4 degrees C, and the net increase in gas release in the stability test is reduced by 35%. Compared with NC/5-AT, the initial activation energy of the mixed system NC/5-AT@ETPE is increased and the activation energy of the reaction process is more stable. The interaction between gas-phase products such as NO2 with NH2CN and HN3 weakens, the characteristic peak of the 5-AT side reaction product NH4 appears, and the decomposition synergy phenomenon between 5-AT and NC is weakened.
The energetic plasticizer 3-azido-2,2-bis(azidomethyl)propyl azidoacetate (ABAMPA) can be employed in double-base propellant formulations due to its efficacy. The thermal properties of ABAMPA were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Non-isothermal DSC measurements at heating rates of 2, 5, 10 and 15 K/min revealed that the exothermic decomposition temperature of ABAMPA ranges from 221.48 to 254.93 degrees C. Further investigation involved analyzing ABAMPA's thermal decomposition kinetics through non-isothermal methods like Kissinger and Flynn-Wall-Ozawa (FWO), offering a critical understanding of its thermal behaviour and potential enhancement in propellant applications. The activation energy, frequency factor and rate constant of the decomposition temperature of ABAMPA were found to be 121.18/123.31 kJ mol-1, 7.56x1011/ 1.27x1012 s-1 and 4.45x10-10/3.17x10-10 s-1, respectively at 298 K, using the Kissinger/FWO methods. Critical temperatures for ABAMPA were assessed as 218.25 degrees C (based on ASTM data) and 218.36 degrees C (according to FWO data). The Kissinger method predicted a half-life of approximately 22.05 years, whereas the FOW method yielded a value of around 30.52 years. In addition the thermodynamic parameter values for the transition state ofABAMPA during thermal decomposition were derived from the Kissinger and FOW methods. The results of this work confirmed the good thermal stability of ABAMPA as an energetic plasticizer.
Exploding Bridge Wire (EBW) detonators are essential for high-reliability, precisely timed explosive initiation in aerospace and defense systems. Their low sensitivity to external disturbances and excellent timing accuracy make them ideal for multi-point detonation, stage separation, and flight termination devices. A new EBW-based initiation system was designed around a platinum bridge-wire mounted on a PCB and pressed into a brass head. The configurations tested included bare wire, RDX initial pressing, and a high-density output pellet. The function time was measured using photodiodes and an oscilloscope, capturing voltage spikes from the post-initiation optical emissions. This setup enabled sub-microsecond time resolution across multiple trials, necessary for the preliminary qualification of a new device type. The function time for the bare wire averaged 3.23 mu s (30 samples), with a jitter of 69 ns. Initial pressing detonation showed a wider time range with a mean of 37 mu s (7 tests). With an output pellet, the mean function time was 9.8 mu s (5 tests), exhibiting low variability and reliable detonation. The photodiode reading was highest for high-output configurations, where products of detonation exposed light emission out of the brass head violently. This EBW system demonstrated excellent performance across all configurations. The experimental results confirm its readiness for integration into flight and warhead systems requiring precise timing.
Eight low signature near-infrared illuminants, with potassium nitrate, the oxidizer(s) and infrared radiation source(s), were prepared via the mechanical mixing method. The micromorphology, thermal reactions, and safety of these materials were evaluated. In particular, as a focus of this work, their combustion performance was investigated via a combinatorial method using a visible and near-infrared light spectrometer (380-1050 nm), a thermal infrared camera, and a high-speed camera. The results indicated that, owing to the use of mechanical mixing, although the ingredients had different particle sizes, they were mixed very homogeneously, which was confirmed by their scanning electron microscopy (SEM) images. The safety of all the energetic composites was very high, as their impact and friction sensitivities were very low and their thermal sensitivity were also low. The differential scanning calorimetry (DSC) data revealed that all the composites had low reaction temperatures, high activation energies, and high thermal stability. Most importantly, regarding the combustion performance, the infrared radiations for all eight composites were very high, but their visible light emissions were very weak. These findings indicate that prepared infrared illuminants have good stealth effect. In the combustion flame of the composites, the gaseous potassium, rubidium and cesium atoms emitted strong near-infrared radiation, but these infrared lights had different wavelengths. In general, the simultaneous use of potassium nitrate, potassium perchlorate, rubidium nitrate, and cesium nitrate as composite oxidizers resulted in excellent infrared emission and poor visible light emission, as well as a moderate burning rate, which meets the requirements for invisible infrared illuminants. These data will be highly valuable for guiding the formula modification of composites in the future.
The Al/CuO system represents a classic thermite reaction system. However, due to limitations such as the relatively low solid-phase reaction rate between the aluminium oxide (Al2O3) film and the Al/CuO system, it has gradually been replaced by other systems. To address these limitations, this study introduces a copper complex (Cu-en) combustion catalyst into theAl/CuO system, leveraging its thermal decomposition characteristics and high catalytic activity. Three distinct preparation methods-electrostatic spraying, spray drying, and solvent evaporation-were employed to synthesize composite materials. Differential Scanning Calorimetry (DSC) analysis demonstrated that the electrostatic spraying method yielded the most favorable performance, with an exothermic peak advancing to 353.13 degrees C and a heat release of 4702.05 J/g. For the spray drying method, two exothermic peaks were observed at 383.04 and 782.94 degrees C, with a total heat release of 2309.16 J/g. In contrast, the originalAl/CuO system and the composite prepared via solvent evaporation did not exhibit any thermite reaction exothermic peaks. Combustion tests revealed that the composite prepared using the electrostatic spraying method exhibited an exceptionally high combustion rate, the widest range of burning speeds, and a response time within 0.5 ms. This phenomenon was further confirmed by SEM (Scanning Electron Microscopy) analysis, which showed that the composites prepared via electrostatic spraying had the highest degree of sphericity, the smallest particle size, and a uniform distribution ofAl and CuO on the spherical surface. A series of tests indicated that introducing Cu-en into theAl/CuO system, combined with the electrostatic spraying method, effectively improved the issues of instability and slow reaction rates in the Al/CuO thermite system. Furthermore, this study utilizedANSYS finite element software to simulate the effects of flow rate, voltage, and receiving distance on particle size during the electrostatic spraying process. An orthogonal experimental design was employed to optimize the electrostatic spraying process, ensuring that the preparation of composites via electrostatic spraying achieved the best possible results.
