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В последние годы объемы пиротехнической продукции российского производства, а также ввозимой из других стран, значительно выросли, в связи с чем увеличилось и число происшествий, связанных с использованием, производством и оборотом таких изделий, которые в ряде случаев становятся предметами и орудиями совершения преступлений. Все больше пиротехнических средств поступает на экспертное исследование, особенно в период праздников, когда такая продукция применяется; отсутствуют методики проведения и рекомендации по производству следственных действий при расследовании преступлений выделенной категории, что в совокупности обусловливает актуальность проведенного исследования. В статье систематизированы теоретические сведения о современных пиротехнических изделиях, рассмотрено их место в современном обществе, в том числе в Республике Таджикистан. Представлены различные определения понятия «пиротехническое изделие» и проведен их анализ. На основе существующих систематизаций пиротехнических изделий разработана и представлена их классификация по различным основаниям., In recent years, the number of pyrotechnic products manufactured in Russia, as well as imported from other countries, has increased significantly, and therefore, the number of incidents related to the use, production and circulation of pyrotechnic products, which in some cases become objects and instruments of crime, has increased. This article is relevant because of the increasing number of pyrotechnics that have been received by experts for research along with, a large number of crime scene inspections, especially during the holidays, are associated with the use of pyrotechnic products. Moreover, there are a lack of methods and recommendations for the production of investigative actions in the investigation of crimes within this particular category. The article systematizes theoretical information about modern pyrotechnic products, considers the position of pyrotechnic products in modern society, including in the Republic of Tajikistan. Various definitions of the term “pyrotechnic product” are presented and an analysis of these concepts is carried out. Based on the existing classifications of pyrotechnic products, their classification was developed and presented on various grounds., Судебная экспертиза, Выпуск 2 (62) 2020

Aluminum (Al)-based thermite, due to its high energy density and low cost, has found wide applications in aerospace propulsion, explosion, pyrotechnics, thermal batteries, and power generations. Though significant efforts have been devoted to improving the ignition and combustion performance of Al-based thermites by using nano-Al, micron-Al (m-Al) remains of practical importance over nano-Al due to its lower cost and smaller dead mass. For m-Al based thermite, the main approach to improve its ignition and combustion performance is to bring Al and metal oxide as close as possible to facilitate the oxidizer diffusion process. Herein, we demonstrated two simple synthesis methods, i.e., the precipitation (PC) method and displacement (DP) method, to prepare m-Al/CuO thermites with the intention to bring Al and CuO to shorter diffusion distance and achieve better dispersion. The PC-thermites have flocculent nanostructured CuO closely attached to the surface of m-Al, and the DP-thermites have a dense shell of CuO coated on the surface of m-Al. Both PC- and DP-thermites have reduced agglomeration and diffusion distance over the traditional mechanically mixed (MM)-thermites that have randomly distributed and agglomerated CuO and m-Al. Consequently, both PC- and DP-thermites exhibit shorter ignition delay time, lower reaction onset temperatures, higher heat release, larger pressure rise, and extended reactivity limits than MM-thermites. Particularly, PC-thermites, due to their flocculent structures, exhibit the shortest ignition delay time, lowest reaction onset temperature, and highest amount of heat release. Moreover, the superior ignition and combustion performance of PC- and DP-thermites is more pronounced under high heating rates over low heating rates. Similar PC and DP methods are applicable to prepare diverse thermites with reduced diffusion distance and improved dispersion to improve their ignition and combustion properties.

This study reports an experimental investigation into the chemical kinetics of several commercial pyrotechnic compositions. A differential scanning calorimeter was utilized to elucidate the thermo-kinetic characteristics of five multicomponent pyrotechnic compositions. The multicomponent nature of practical pyrotechnics results in a complex interaction between the various components as well as condensed phase reactions. The thermo-kinetic study was carried out to approximate the heating experienced by the pyrotechnics before the combustion zone. The chemical kinetic parameters such as overall activation energy (Ea) and pre-exponential factor (A) corresponding to these reactions were estimated using Friedman and Starink method. The large variation in Ea attributed to multiple parallel reactions was addressed through the application of deconvolution techniques utilizing the Frazer-Suzuki function as well as nonlinear mechanistic modelling. The observations from the DSC data and the comparison between the deconvolution techniques provided an insight into the phenomenology of the combustion process of energetic pyrotechnics.

In the Netherlands, the illegal use of powerful flash bangers is popular and as a result these items are frequently encountered in forensic casework. In collaboration with the Dutch police a representative sample set of the most frequently confiscated flash bangers, the Cobra 6 and Cobra 6 2G, has previously been collected also including imitation items. Classification of the different flash bangers was performed by analysing the pyrotechnic charge using capillary electrophoresis (CE) with indirect UV-detection. Two rapid CE methods were used to determine the anions and cations present in the pyrotechnic mixtures. Black and flash powders were easily distinguishable based on their main inorganic compositions,i.e., KNO3and KClO4, respectively. Differentiation of flash powders from the commercial and imitation pyrotechnic items was achieved by the identification of Ca2+and Mg2+cation traces in the imitation flash banger powders. Quantitative CE results were used to explore the possibilities to differentiate seized sets of flash bangers but this proved to be difficult for commercial items due to lack of impurities and uniform production processes. In addition, inherent inhomogeneity of the powders and incomplete sample extraction yielded a relative high measurement uncertainty within a set. For the imitation items potential for set-based differentiation was observed. Although the number of seized imitation sets was limited, a first step has been taken to classify pyrotechnic mixtures to provide additional information and intelligence in forensic casework of flash bangers.

Glycidyl azide polymer (GAP), an energetic binder, is the focus of this review. We briefly introduce the key properties of this well-known polymer, the difference between energetic and non-energetic binders in propellant and explosive formulations, the fundamentals for producing GAP and its copolymers, as well as for curing GAP using different types of curing agents. We use recent works as examples to illustrate the general approaches to curing GAP and its derivatives, while indicating a number of recently investigated curing agents. Next, we demonstrate that the properties of GAP can be modified either through internal (structural) alterations or through the introduction of external (plasticizers) additives and provide a summary of recent progress in this area, tying it in with studies on the properties of such modifications of GAP. Further on, we discuss relevant works dedicated to the applications of GAP as a binder for propellants and plastic-bonded explosives. Lastly, we indicate other, emerging applications of GAP and provide a summary of its mechanical and energetic properties.

Finding a straightforward counter to infectious biological agents, such as Bacillus anthracis, is of great interest. We have found that a pyrotechnic mixture of iodate salts and aluminum is highly effective at producing heat and elemental iodine, both of which are considered as effective biocides. What is required is a general method of application. This paper outlines an approach to creating sprayable pyrotechnics. Polyurethane foams (energetic and non-energetic), nitrocellulose, and glycidyl azide polymer (GAP) have been applied as binders to pyrotechnic mixtures. Heat produced upon burning these formulations was quantified by bomb calorimetry, while iodine output was quantified by ultraviolet-visible spectroscopy (UV-Vis). The nitrocellulose-pyrotechnic formulation in acetone created a sprayable matrix, which dried to paint-like consistency. While the polyurethane-pyrotechnic was also sprayable, it was dried to a rigid, flammable foam. Properly formulated, all produced significant heat and iodi...

Energetic materials (explosives, propellants and pyrotechnics) are used in a broad range of public and private sector applications. The design of novel, safe materials is therefore of critical importance. At present, physical mechanisms able to rationalize the impact sensitivity properties of energetic materials remain limited. Investigation therefore has required lengthy synthesis and experimental testing. Based on knowledge of the effects of mechanical impact, an ab initio model is developed to rationalize and describe the impact sensitivity of a series of crystalline energetic azide materials. It is found that electronic excitation of the azido anion is sufficient to permit bond rupture, and therefore offers a plausible mechanism for initiation of these materials. The athermal excitation can be achieved through consideration of nonadiabatic vibronic processes. Across the series of azides studied here, the electronic structure of the azido anion is found to remain largely constant. By considering only the relative rates of vibrational energy transfer within the crystalline materials it is found that a direct correlation exists between the relative impact sensitivity and the rate of energy upconversion. Thus, the present contribution demonstrates a fully ab initio method to describe the athermal initiation of ideal, crystalline energetic materials, and predict their relative sensitivity. Without the need for any experimental input beyond a crystal structure, this method therefore offers a means to selectively design novel materials for targeted application.

In many types of spacecraft and missile systems, the vehicle’s skin cutting are carried out by using the mild-detonating fuse (MDF) or the flexible linear shaped charge (FLSC). MDF is a very thin metal tube that filled with explosive charges and has an axisymmetric shape. FLSC is an inverted chevron-shaped flexible tube that generates hypervelocity jet to penetrate or cut thick metal structures. In this study, the characteristics of MDF and FLSC for metal plate cutting are identified. First, the fracture mechanisms due to MDF and FLSC are numerically analyzed in 2-D plane strain using ANSYS AUTODYN, one of commercial hydrocodes. By using proposed numerical scheme, the effects of the cutting methods and the design parameters on cutting performance, fragmentation and backward shock waves are studied; the pros and cons of MDF and FLSC for metal plate cutting are clarified. The numerical method and the results of this study provide the guidelines to select metal plate cutting method and help to establish the design method for optimal metal plate cutting; the number of the expensive explosive experiments can be reduced.

High volume screening of parcels with the aim to trace the illegal distribution and selling of fireworks using postal services is challenging. Inspection services have limited manpower and means to perform extensive visual inspection. In this study, the presence of solid pyrotechnic residues collected from cardboard shipping parcels containing fireworks was investigated for direct in-field chemical detection. Two emerging trace detection techniques, i.e., capillary electrophoresis (CE)-based inorganic oxidizer detector and infrared thermal desorption (IRTD) coupled with direct analysis in real time mass spectrometry (DART-MS) were investigated for their potential as screening tools. Detection of non-visible pyrotechnic trace residues from real-case seized parcels was demonstrated using both screening techniques. However, the high nitrate background in the commercial CE system complicated its screening for black powder traces. In addition to rapid screening, IRTD-DART-MS allowed differentiation between flash and black powder by identification of the molecular inorganic ions. Compared to the portable CE instrument, rapid screening using IRTD-DART-MS is currently limited to laboratory settings. The capabilities of these emerging techniques established solid particle and trace residue chemical detection as interesting options for parcel screening in a logistic setting.

Traditional pyrotechnics and fireworks require combustion and extreme levels of heat to operate. This makes them incredibly dangerous. In response to this phenomenon, the author developed a smart material fireworks machine that uses metal powder as the object of spraying. This article details the hardware selection and program development process of the main functional modules. The hardware selection and the process of program development of the main functional modules are introduced in detail. The speed regulation module of DC brushless electric machine is designed and the PID control algorithm is adopted to realize the digital control of the spraying height of the fireworks. A close-range wireless communication system based on 2.4G is designed to realize multi-machine online intelligent control of fireworks. Finally, the intelligent control system is tested online. The results show that the fireworks machine has high anti-interference ability and can effectively receive communication information; meanwhile, the system runs stably and reliably. For this reason, the fireworks machine can well replace the traditional disposable cold firework barrel and become the standby of stage performance equipment.

A microfluidic paper-based analytical device (µPAD) has been developed for the onsite determination of low explosives residues. The device is capable of simultaneous detection of a variety of metallic salts using colorimetric detection. The µPAD was printed on chromatography paper with wax ink, allowing for the creation of a set of hydrophobic channels. Each channel contains a specific set of reagents that yields a color change upon interaction with a specific metal salt. The device is capable of performing six simultaneous tests, including the detection of metallic salts present in primer residues and pyrotechnic low explosive devices. Metals detected include lead, barium, antimony, iron, aluminum, zinc, and magnesium. Detection times were found to be less than 10 min and visual limits of detection ranged from 0.025 to 0.4 µg of these metallic compounds. The resultant paper chip was then tested against various interferences and used to examine a number of different pyrotechnic compositions. This new device should prove useful in onsite detection of post-blast residues of pyrotechnics in the field due its portability and ease of use.

Pyrotechnics (fireworks) displays are common for many cultures worldwide, with Independence Day celebrations occurring annually on July 4th as the most notable in the U.S. Given an episodic nature, fireworks aerosol properties are poorly characterized. Here we report observations of optical properties of fresh smoke emissions from Independence Day fireworks smoke sampled at Los Alamos National Laboratory, New Mexico U.S.A. on 4–5 July 2016. Aerosol optical properties were measured with a photoacoustic extinctiometer (PAX, DMT, Inc., Model 870 nm) at low RH

The paper presents the results of forensic analysis of improvised dummy grenades modeled after the airsoft hand grenade RGS-4 for use in tactical simulation wargames like «Airsoft». Initial testing by experts affiliated with a different system of forensic science institutes led to the conclusion that these devices are capable of producing explosions and causing fragmentation damage. The purpose of this study conducted by two forensic science centers of the Ministry of Justice of the Russian Federation was to correct the classification of improvised devices as explosive devices. Results indicate that these devices that consist of a cardboard (paper) or rubber-like casing filled with dried peas, with a «Korsar-4» firecracker in the middle, have the formal characteristics of an explosive device but cannot be regarded as such (as per Article 222 of the Criminal Code of the Russian Federation), since they are in effect typical imitation pyrotechnic devices similar to dummy hand grenades RGS-4 and display no significant damaging properties.

The effect of mass ratio of fuel to oxidant in pyrotechnic compositions of Mg/Ba(NO3)2 and Mg/Sr(NO3)2 was studied using the non-isothermal thermogravimetry (TG) and differential scanning calorimetry (DSC) techniques. The mass ratios 10:90, 25:75 and 50:50 of Mg powder to oxidant (nitrate salt) were used for preparation of pyrotechnic compositions. The kinetic parameters of thermal ignition reactions of pyrotechnics were obtained by using TG/DSC curves under nitrogen atmosphere at heating rates of 20, 25 and 30 °C min−1. The DSC curves showed that the 25:75 weight ratio of fuel to oxidant resulted in a complete ignition reaction and showed the highest enthalpy of the reaction. Also, this mass ratio was not indicated a mass gain after the combustion step in the TG curves. The model-free methods of Kissinger, Ozawa–Flynn–Wall (OFW) and Kissinger–Akahira–Sunose (KAS) were used for calculation of activation energy (Ea) of ignition reactions of pyrotechnics. The Ea values 130.5 and 146.3 by Kissinger, 138.3 and 153.2 by OFW and 132.2 ± 2.4 and 146.3 ± 1.7 kJ mol−1 by KAS methods, respectively, were obtained for Mg/Ba(NO3)2 and Mg/Sr(NO3)2 pyrotechnics. Also, the nonlinear model-fitting method was used to determine the pre-exponential factor (A) and kinetic model function. The sigmoidal shapes were resulted from the curves of conversion factor (α) versus T. The model of A3/2 with the functions of g(α) = [− ln(1 − α)]2/3 and f(α) = 3/2(1 − α)[− ln(1 − α)]1/3 as a nucleation reaction model was proved by using the model-fitting method for the ignition reaction of both pyrotechnic compositions. The ln A values 8.1 and 7.6 min−1 were obtained, respectively, for the ignition reaction of magnesium powder with Ba(NO3)2 and Sr(NO3)2.

This study reports a reduced order model for the prediction of the burning rate of pyrotechnic compositions. The combustion process of most pyrotechnics is primarily driven by condensed phase reactions. A priory estimation of the burning rate of pyrotechnics with multiple components may not be possible using the established methods. The study provides a simplified approach based on integral analysis of a proposed combustion wave structure for estimating the burning rate when the pyrotechnic composition, pure component thermo-physical properties, and thermo-kinetics parameter are known. The proposed combustion wave assumes a staged combustion process where the oxidizer undergoes decomposition in a broad reactive zone while fuel combustion occurs in a thin surface region. This approach takes account of the effective thermal conductivity as well as porosity of the pyrotechnic matrix. The pyrotechnic compositions studied here are expected to burn conductively at atmospheric pressure with little or no overpressure. The phenomenology of the combustion process of energetic materials is elucidated, and the reduced order model is validated through a case study.

A pyrotechnic composition of aluminum, zirconium, and potassium perchlorate was prepared to obtain suitable safety and sensitivity. The thermal behavior, microstructure, and composition of the pyrotechnic compositions heated from 300 °C to 600 °C were investigated using differential scanning calorimetry (DSC), thermogravimetry (TG), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) to evaluate the properties of the pyrotechnics after the high-temperature process, such as the 1 A/1 W no-fire test. When the heating temperature increased, the sharp exothermic peak near 530 °C decreased, corresponding to the reaction of metal powders with potassium perchlorate. Gradual oxidizing reaction between Zr and KClO4 can occur in solid stage when the temperature exceeds 400 °C. With the increase of the heating temperature from 400 °C to 600 °C, the mass losses in TG curves decreased, and melted particles of KClO4 appeared gradually. The Al/Zr/KClO4 pyrotechnic composition was safe in the of 1 A/1 W no-fire test. Hence, Al/Zr/KClO4 can be used in flash pyrotechnics, fireworks, and fuel-rich propellants.

Fine Ti powders were prepared through magnesiothermic reduction in TiO2–Mg–Ca mixtures under 4 MPa of Ar followed by acid leaching (with HCl or HNO3) and characterized by XRD, SEM/EDS, and chemical analysis. Thus prepared Ti powders exhibited the specific surface ranging between 7.0 and 30.0 m2/g. The produced Ti powders can find their application in pyrotechnics, powder metallurgy, and as raw material for SHS of inorganic compounds.

Metal-based thermites, especially those based on aluminum, have been recently included in materials for energetic applications such as pyrotechnics, propellants, and explosives. In parallel, several advances in the field of Metal-Organic Frameworks (MOFs) and Coordination Polymers (CPs) have as well paved the road for their use in developing novel energetic materials. In this context, we are introducing new thermites compositions with low ignition temperature, stable propulsive force, and high reactivity. These thermites are based on the [Cu4Na(Mtta)5(CH3CN)]n (Mtta = 5-Methyl-1H-tetrazole) energetic metal-organic framework (EMOF-1) as a fuel instead of pure metals. We first report the synthesis of an energetic MOF via the microwave-assisted technique as a more rapid and greener method. The efficiency of composites based on EMOF-1 and Al together with various oxygenated salts were investigated. Multiple instruments are involved to characterize the morphology and the structure of EMOF-1 and the developed systems, such as SEM-EDX, FTIR, and XRD. The combustion behavior of the novel composites was evaluated by TGA/DSC, bomb calorimetry and laser ignition. Additionally, the apparent kinetic parameters (activation energy & frequency factor) were calculated by the Kissinger and Ozawa approaches. The results revealed that the new thermite mixtures exhibit superior combustion characteristics of one and half to two-folds the average heat of combustion compared to aluminum-based ones, at almost half the ignition temperature. In this sense, the combustion reaction proceeds faster, easier (reduced activation energy), the ignition temperatures are noticeably lowered, and the heat released has considerably improved. In addition, they exhibited stable force with longer burning time. Among them, EMOF-1/KIO4 thermite exhibits the highest heat release (4.7 kJ/g), while EMOF-1/NH4NO3 thermite shows the lowest onset reaction temperature (224 ᵒC). EMOF-1/KClO4 yields the highest average force (8.4 N), calculated pressure (1365 kPa), pressurization rate (0.32 kPa/μs) and the longest burning time assigned to EMOF-1/K2S2O8 (40 ms).

This review article consists of efforts focused on the development of illuminating pyrotechnics. Examined will be the methods of generating red-, green-, yellow- and blue-light-emitting illuminating pyrotechnics. Ways to improve luminosity, spectral purity, and burn rate will be discussed. Recently developed formulations concerning the development of environmentally friendly illuminating pyrotechnics will also be presented.

Metal nanoparticles tend to deactivate due to spontaneous migration-aggregation and continuous surface oxidation. Nanocapsules provide a brand-new strategy to tackle these challenges. In this work, two types of nanocapsules were designed and applied to active aluminum. The self-assembly details between carbon nanotubes (CNTs) and aluminum nanoparticles (ANPs) are elucidated through molecular dynamics methods. The stability and controllability of capsules I-VI consisting of various lengths of CNTs were revealed by means of reactive molecular dynamics simulations. The results indicate that the driving force for the self-assembly of nanocapsules is the vdW interaction. The assembled capsule has excellent stability, and the interaction energy between the tube and ANPs and between the tubes is as high as −599.55 and −1,014.78 kcal/mol, respectively. The opening of the nanocapsules during combustion is dependent on the length of the CNTs and temperature. Above 2000 K, the outer CNT can be opened when the length is greater than 31.73 A. When used as propellants, pyrotechnics and explosives, these nanocapsules can be triggered remotely by visible/infrared lasers without the need of detonating wires.

Polytetrafluoroethylene/Aluminum (PTFE/Al) composite with high energy density and combustion reaction performance has received widespread attention in the field of propellants, explosives, and pyrotechnics. In order to precisely control combustion reaction and energy output performance, gradient structured PTFE/Al composite (mass and diameter gradient) has been designed and constructed through 3D printing technology. PTFE/Al ink is prepared by acoustic resonance mixing to control rheological properties (viscosity and modulus) for 3D printing technology. The largest reaction heat (7749.95 J/g) and burning rate (~130 mm/s) are achieved for gradient lines with diameter of 2.42 mm and mass ratio of 60:40 (PTFE/Al). Moreover, the progressive change from steady combustion to deflagration containing three stages of pressure output is observed for gradient structured PTFE/Al cylinder. This work reveals that gradient structure could provide new strategy to tune energy output and combustion performances, which can promote the practical application of PTFE/Al reactive materials.

Reactive materials consisting of aluminum (Al) and fluorine-containing oxidizers have been extensively developed owing to high energy density and potential applications in propellants and explosives. Herein, graphite fluoride (CF) as a new fluorine-containing oxidizer was introduced to construct nano-Al based reactive materials. Systematic investigation and comparison were executed on exothermic reaction behavior and combustion performance of nano-Al/CF and nano-Al/polytetrafluoroethylene (PTFE) based reactive materials. The energy output and exothermic peak of nano-Al/CF were approximately 2367 J/g and 641 °C, which were 300 J/g and 85 °C higher than those of nano-Al/PTFE, respectively. The effects of nano-Al/CF mass ratio and packing density on burning rates were examined to fully understand combustion reaction and flame propagation behavior. Nano-Al/CF exhibited excellent burning rate (1670 m/s), much higher than that of nano-Al/PTFE (930 m/s). More interestingly, flame splitting phenomenon including three distinct flame regions was observed on the critical position with the highest burning rate for nano-Al/CF with the mass ratios of 25/70 and 30/75. The burning rate of nano-Al/CF increased and then decreased with the packing densities ranging from 20.87% to 53.47% TMD. The dominating combustion reaction products (AlF3 and C) were further determined to figure out the reaction mechanism. These results demonstrated that CF as fluorine-containing oxidizer to construct reactive materials has potential applications in propellants, explosives and pyrotechnics.