Electrostatic Spark Sensitivity Research Articles

Prediction of impact sensitivity and electrostatic spark sensitivity for energetic compounds by machine learning and density functional theory

Prediction of impact sensitivity and electrostatic spark sensitivity for energetic compounds by machine learning and density functional theory

Study on synthesis and characterization of spherical copper(I) 5‐nitrotetrazolate (DBX‐1)

AbstractTraditional primary explosives often contain heavy metals, especially toxic lead, such as lead azide (LA) and lead styphnate (LS) that can cause environmental pollution problems. Copper(I) 5‐nitrotetrazolate (DBX‐1) is a green primary explosive without toxic heavy metals, which is considered as one of the most promising alternatives to LA. DBX‐1 is usually synthesized from sodium 5‐nitrotetrazolate dihydrate (NaNT ⋅ 2H2O) and copper(I) chloride (CuCl). However, most of the synthesized products are irregular flakes with poor flowability, which affects the loadability. In this study, dextrin was used as a crystal shape modifier to improve the morphology of the synthesized product. Taguchi analysis method was used to determine the optimal experimental conditions for obtaining the spherical DBX‐1 with smaller particle size. The synthesized products were characterized by SEM, FTIR, UV‐Vis, STA TG‐DSC and VST, and their sensitivity was determined by BAM fallhammer, BAM friction tester and electrostatic spark sensitivity tester. The experiment results showed that the optimal combination of synthesis parameters was the NaNT ⋅ 2H2O concentration of 4.4 wt.%, the reaction temperature of 100 °C, the reaction time of 75 min and the additional dextrin solution of 5.0 mL. The average particle size of the synthesized spherical DBX‐1 was 33.0 μm. The decomposition activation energy was calculated by Kissinger method and Ozawa method to be 178.5 and 178.8 kJ/mol, respectively. The compound had good chemical stability. In addition, the sensitivity of spherical DBX‐1 was lower compared to that of flaky DBX‐1 and LA.

Preparation and Characterization of PANI Surface Modified HMX/F2602 Microcapsule Composites

AbstractUsing HMX with a particle size of 1–10 μm as the main explosive, a dense polyaniline (PANI) shell was prepared on the surface of HMX/F2602 by in situ polymerization, and an energetic composite material HMX−F@PANI (HMX−F2602@PANI) with a microcapsule structure was constructed. The structure and properties of the samples were characterized by SEM, XRD, XPS, DSC, mechanical sensitivity and electrostatic spark sensitivity tests. The results showed that the chemical structure and polycrystalline morphology of the crystals did not change during the coating process, and remained β‐HMX. The preparation of PANI shell greatly improves the coating degree of the explosive surface and reduces the exposure of crystal. In addition, compared with HMX/F2602, HMX−F@PANI is more excellent in improving thermal stability and reducing the electrostatic spark sensitivity, which is attributed to the advantages of microcapsule structure and good electrical conductivity of PANI.

Preparation of 4,6-Dinitro-7-Oxygen-Benzofuraxan Sodium Salt (Nadnp) by “One-Pot” Method

4, 6-dinitro-7-oxygen-benzofuraxan sodium salt (NaDNP) was synthesized from 3-bromo-2, 4, 6-trinitroanisole and sodium azide by Substitution reaction and Cyclization reaction in water with an overall yield of 78%. Its structure was characterized by 1NMR, 13C NMR and IR, and its thermal properties were studied by Differential Scanning Calorimetry. The sensitivity performance was studied by impact sensitivity, flame sensitivity and electrostatic spark sensitivity. The results show that the DSC peak value of the sample is 282.45 °C under the protection of nitrogen when the heating rate is 10 °C / min. The impact sensitivity H50 is 38.2m, the flame sensitivity H50 is 13.6cm, and the electrostatic sensitivity E50 is 0.51J. Compare with LTNR, NaDNP is an insensitive new type of primary explosive.

Performance of copper(II)-azide with hydrogen bonding as initiating explosive

The development of high-performance initiating explosives through energetic complexes is considered a feasible way to satisfy military and civilian applications. Compared with other reported initiating explosives, copper(II)-azide is a more promising candidate due to its stronger initiation ability and green nature. However, its instability towards mechanical and electrostatic stimulation hinders its application. This study aimed to propose an effective strategy for stabilizing highly sensitive and explosive copper(II)-azide via hydrogen bonding with NH2-substituted ligands. Using this method, two highly energetic polymers, [Cu(MAT)(N3)2]n (CMA-1) and [Cu4(MAT)2(N3)8(H2O)]n (CMA-2), based on 1-methyl-5-aminotetrazole (MAT), were synthesized and confirmed by single-crystal x-ray diffraction. The experimental results showed that both CMA-1 and CMA-2 had improved thermal stability and reduced mechanical and electrostatic sensitivities to meet practical applications, demonstrating the feasibility of stabilizing the copper(II)-azide system through hydrogen bonds. Especially, combining a series of advantages, including nontoxic metal (Cu), high nitrogen content (62.5%), high thermal decomposition temperature (223.3 °C), good sensitivities (impact sensitivity = 1.0 J; friction sensitivity = 30 N; electrostatic spark sensitivity = 201.6 mJ), powerful ignition capability (minimum primary charge = 10 mg), and simple synthesis, CMA-2 exhibited comprehensive performance beyond those of all other initiating substances to date. In particular, the electrostatic spark sensitivity (201.6 mJ) is at least 720 times higher than that of the original CA powder (<0.28 mJ), making it a promising candidate for new-generation initiating explosive.

Optimization of Synthesis Parameters and Characterization of Green Primary Explosive Copper(I) 5‐Nitrotetrazolate (DBX‐1)

AbstractSince the early 20th century, lead azide (LA) has been commonly used as a primary explosive. However, lead pollution in the air and soil has attracted more and more attention, particularly in military training grounds and shooting ranges. Copper(I) 5‐nitrotetrazolate (DBX‐1) is considered as one of the most promising alternatives to LA. DBX‐1 is typically prepared from sodium 5‐nitrotetrazolate dihydrate [NaNT(H2O)2] and copper(I) chloride (CuCl). But little is known about its optimal synthesis parameters. In addition, NaNT(H2O)2 is not commercially available. In this study, NaNT(H2O)2 was prepared by ourselves. Taguchi's experimental design method was used to determine the optimal experimental conditions for obtaining the maximum yield of DBX‐1. The synthesized NaNT(H2O)2 and DBX‐1 were identified by means of SEM, NMR, FTIR, EA, UV‐Vis and STA TG‐DSC, and the sensitivity of DBX‐1 was determined using BAM fallhammer, BAM friction tester and electrostatic spark sensitivity tester. The experimental results indicated that the optimal synthesis parameters of DBX‐1 were as follows: the reaction temperature was 100 °C, the reaction time was 30 min, the concentration of NaNT(H2O)2 was 0.075 wt.% and the molar ratio of NaNT(H2O)2 to CuCl was 1.15, and then the maximum yield after purification could reach 72.2 %. The decomposition activation energies of DBX‐1 calculated by Kissinger and Ozawa methods were 178.6 and 179.0 kJ/mol, respectively. In addition, the impact sensitivity, friction sensitivity and electrostatic spark sensitivity of DBX‐1 were 51 mJ, 0.4 N and 7.3 mJ, respectively, which were almost the same as those for LA.

Study on Synthesis and Characterization of Primary Explosive KDNBF with Different Morphologies

AbstractTraditional primary explosives are usually heavy metal salts, especially salts of lead, such as lead azide (LA) and lead styphnate (LS), which can cause environmental pollution problems. The potassium salt of 4,6‐dinitrobenzofuroxan (KDNBF) has attracted more and more attention due to its advantages of no heavy metal pollution to the environment and appropriate sensitivity. There are many reports on the thermal properties and applications of KDNBF, but few reports on the morphological properties. In addition, little is known about the optimal synthesis conditions of KDNBF with different morphologies in the preparation process. In this study, Taguchi's experimental design method was used to determine the optimal experimental conditions for obtaining the maximum yields of KDNBF with different morphologies. The synthesized KDNBF was identified by means of SEM, NMR, FTIR, EA, and TG‐DSC, and its sensitivity was measured using BAM fallhammer, BAM friction tester, and electrostatic spark sensitivity tester. The experimental results indicated that the maximum yields of flaky and spherical KDNBFs could reach 85.6 % and 82.6 % after purification under the optimal experimental condition, respectively. The spherical KDNBF powder had a relatively denser structure than the flaky KDNBF powder. The thermal analyses showed that the activation energies of the decomposition reaction of the flaky and spherical KDNBF powders calculated by the Kissinger method were 171.5 and 188.5 kJ mol−1, respectively, and the Ozawa method were 170.7 and 186.9 kJ mol−1, respectively. The thermal stability of spherical KDNBF powder was higher than that of flaky KDNBF powder. In addition, the sensitivity tests showed that the spherical KDNBF powder was less sensitive than the flaky KDNBF powder.

Optimization of the Process Parameters for the Synthesis of High Purity 4,6‐Dinitrobenzofuroxan (4,6‐DNBF)

Abstract4,6‐Dinitrobenzofuroxan (4,6‐DNBF) is explosive and can also be used as an important intermediate in the synthesis of other explosives. It can be prepared by nitrating benzofuroxan (BF) with mixed nitric/sulfuric acid. However, little is known about its optimal synthesis parameters in the preparation process. In this study, Taguchi's experimental design method was used to improve the yield of 4,6‐DNBF. A L9 (34) orthogonal array with four control factors and three levels of each control factor was used to design nine experimental conditions. The experimental data were transformed into a signal‐to‐noise (S/N) ratio to analyze and evaluate the experimental conditions of the optimal parameter combination for the maximum yield of 4,6‐DNBF. The verification results indicated that the optimal synthesis parameters were as follows: nitration temperature was 40 °C, mass ratio of BF to H2SO4, was 1 : 15, volume ratio of HNO3 to H2SO4 was 1 : 2.0 and reaction time was 4 hours, and then the maximum crude yield and the maximum yield after purification could reach 73.2 % and 49.0 %, respectively. Furthermore, the synthesized 4,6‐DNBF was identified by scanning electron microscopy (SEM), nuclear magnetic resonance spectrometer (NMR), Fourier transform infrared spectrometer (FTIR), elemental analyzer (EA), ultraviolet‐visible spectrometer (UV‐Vis) and thermogravimetry‐differential scanning calorimetry (TG‐DSC), and its sensitivity was determined using BAM fallhammer, BAM friction tester, and electrostatic spark sensitivity tester.

Design of new energetic materials based on derivatives of 1,3,5-trinitrobenzenes: A theoretical and computational prediction of detonation properties, blast impulse and combustion parameters

This paper reports the design of some of the new ionic based high energy materials derived from the anion of picric acid (2,4,6-trinitrobenzene-1-ol), styphnic acid (2,4,6-trinitrobenzene-1,3-diol) and 2,4,6-trinitrophloroglucinol (2,4,6-trinitrobenzene-1,3,5-triol) and cation derived from the key synthon molecules such as 5-trifluoromethyl-1H-tetrazole, 5-dinitromethyl-1H-tetrazole and 5-azido-1H–tetrazole-1-carbonitrile. The detonation properties of these newly proposed compounds are predicted by using software such as EXPLO-5, EXTEC and LOTUSES and Keshvarz method. Moreover, other explosive parameters such as density, gurney velocity, and oxygen balance and decomposition products of the newly designed molecules have also been predicted and reported for the first time in this manuscript. The predicted detonation parameters of some of the newly designed compounds exhibit higher velocity of detonation (VOD) and detonation pressure in comparison to other well-known benchmark explosives such as 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-1,3,5-triazinane (RDX). Further, the peak over pressure (POP) and the blast impulse parameters of the newly designed compounds are predicted by using Shock physics explicit eulerian dynamics (SPEED) software, and the same is reported for the first time in this work. The work also reports the theoretical prediction of impact and electrostatic spark sensitivity parameters for the newly designed molecules. The ballistic performance parameters of the newly designed ionic energetic materials are also predicted by incorporating them into model composite rocket propellant formulations. The predicted ballistic parameters indicate that the proposed materials may find an application in the propellant formulation as an energetic additive.

Preparation of mono-dispersed, high energy release, core/shell structure Al nanopowders and their application in HTPB propellant as combustion enhancers

Mono-dispersed, spherical and core/shell structure aluminum nanopowders (ANPs) were produced massively by high energy ion beam evaporation (HEIBE). And the number weighted average particle size of the ANPs is 98.9 nm, with an alumina shell (3–5 nm). Benefiting from the passivation treatment, the friction, impact and electrostatic spark sensitivity of the ANPs are almost equivalent to those of aluminum micro powders. The result of TG-DSC indicates the active aluminum content of ANPs is 87.14%, the enthalpy release value is 20.37 kJ/g, the specific heat release S1/Δm1* (392–611 °C) which determined the ability of energy release is 19.95 kJ/g. And the value of S1/Δm1* is the highest compared with ANPs produced by other physical methods. Besides, the ANPs perfectly compatible with hydroxyl-terminated polybutadiene (HTPB), 3 wt. % of ANPs were used in HTPB propellant replaced micron aluminum powders, and improved the burning rate in the 3–12 MPa pressure range and reduced the pressure exponential by more than 31% in the 3–16 MPa pressure range. The production technology of ANPs with excellent properties will greatly promote the application of ANPs in the field of energetic materials such as propellant, explosive and pyrotechnics.

Encapsulation of Cyclotetramethylenetetranitramine (HMX) by Electrostatically Self-Assembled Graphene Oxide for Desensitization

To improve the safety of cyclotetramethylenetetranitramine (HMX) particles, a novel strategy was developed for the fabrication of graphene oxide encapsulated HMX (HMX@GO) by electrostatic self-assembly between graphene oxide and HMX particles. The prepared samples were characterized by optical microscopy, scanning electron microscopy, Raman spectroscopy, X-ray photon spectroscopy, thermogravimetry, differential scanning calorimetry and water contact angle tests. The results revealed that GO sheets were coated densely and homogeneously on the HMX particles in a HMX@GO composite at a low GO content of about 0.23 wt %. Compared with that of raw HMX, the impact sensitivity of the HMX@GO composite decreased from 100 % to 30 %, and the 50 % probability of required ignition energy (E50) in the electrostatic spark sensitivity test increased from 0.66 J for HMX to 1.12 J for the HMX@GO composite, suggesting that the electrostatically self-assembled GO coating layer could obviously enhance the safety of HMX.

Graphene nanoplatelets/lead azide composites for the depressed electrostatic hazards

Graphene nanoplatelets/lead azide composites (GLA) were prepared by adding graphene nanoplatelets (GNP) to the reaction solution or coating the normal lead azide (LA) with GNP. Scanning electron microscopy (SEM), Raman spectroscopy and X-ray diffraction (XRD) were used to characterize the morphology and the composition of the products. The electrostatic spark sensitivity and static electricity accumulation of the obtained samples were investigated in detail. Results exhibit excellent anti-electrostatic performance.

The facile synthesis of graphene nanoplatelet–lead styphnate composites and their depressed electrostatic hazards

Graphene nanoplatelet–lead styphnate composites (GLS) were prepared either by adding graphene nanoplatelets (GNP) to the reaction solution or by coating normal lead styphnate (LS) with GNP. The composites exhibited excellent anti-electrostatic performance with depressed electrostatic spark sensitivity and static electricity accumulation.

A Novel Insensitive High Explosive 3,4‐Bis (Aminofurazano) Furoxan

AbstractA novel insensitive high explosive 3,4‐bis (aminofurazano) furoxan (BAFF) was prepared using 3‐amino‐4‐acylchloroximinofurazan (ACOF) as a precursor. The molecular and crystal structures of BAFF were characterized by IR, MS, 1H NMR, 13C NMR, elemental analysis, and single crystal X‐ray diffraction. The single crystal structure of BAFF recrystallized from water is monoclinic, space group P 21/c, and ρc=1.745 g cm−3, and that recrystallized from ethanol is triclinic, space group P 1, and ρc=1.737 g cm−3. BAFF has multiple crystal forms. The calculated detonation velocity by BKW code is 8100 m s−1 (ρ=1.795 g cm−3, theoretical density calculated by quantum chemistry) and the experimental value is 7177 m s−1 (ρ=1.530 g cm−3, charge density). The tested values of impact, friction, and electrostatic spark sensitivity show that BAFF is insensitive.

Preparation, characterization, non-isothermal reaction kinetics, thermodynamic properties, and safety performances of high nitrogen compound: Hydrazine 3-nitro-1,2,4-triazol-5-one complex

A new high nitrogen compound hydrazine 3-nitro-1,2,4-triazol-5-one complex (HNTO) was prepared by the reaction of 3-nitro-1,2,4-triazol-5-one with hydrazine hydrate, and its structure was characterized by means of organic elemental analyzer, FT-IR, XRD, 13C NMR and 15N NMR. The non-isothermal reaction kinetics of the main exothermic decomposition reaction of HNTO was investigated by means of DSC. The thermodynamic properties of HNTO were calculated. The results showed that the formation of HNTO is achieved by proton transfer of N(4) atom, and it makes a higher nitrogen content and lower acidity. The reaction mechanism of HNTO is classified as nucleation and growth, and the mechanism function is Avramo–Erofeev equation with n = 2/5. The kinetic parameters of the reaction are E a = 195.29 kJ mol −1, lg( A (s −1)) = 19.37, respectively. The kinetic equation can be expressed as: d α d t = 10 18.97 ( 1 − α ) [ − ln ( 1 − α ) ] 3 / 5 e − 2.35 × 10 4 / T The safety performances of HNTO were carried out. The critical temperature of thermal explosion are 464.26 and 474.37 K, the adiabatic time-to-explosion is 262 s, the impact sensitivity H 50 = 45.7 cm, the friction sensitivity P = 20% and the electrostatic spark sensitivity E 50 > 5.4 J (no ignition). It shows that HNTO has an insensitive nature as RDX and NTO, etc.

Primary explosives: Electrostatic discharge initiation, additive effect and its relation to thermal and explosive characteristics

All explosives, under all conditions must be considered vulnerable to generation, accumulation and discharge of static charge. The low energy static hazards of the order as low as 2–3 mJ need to be guarded against in case of highly sensitive compounds namely primary explosives. The hazard is normally associated with manufacturing and filling operations due to discharge of static charge accumulated on a person supplying energy up to 20 mJ. To reduce the risk associated with static initiation hazard in the processing and handling of the explosives, the electrostatic sensitivity tests can provide an important input regarding electrostatic hazards. This paper presents electrostatic sensitivity data in terms of zero ignition probability data ( E SE0) of some of the initiatory explosives such as nickel/cobalt hydrazinium nitrate, silver azide, lead azide and mercury salt of 5-nitro tetrazole. Similar data has also been presented for samples coated with polyvinyl pyrrolidone to study its effect on electrostatic sensitivity. The electrostatic spark sensitivity of some conventional and novel made to explain the increased spark sensitivity behavior on the basis of the possible primary explosives has been studied. The electrostatic spark sensitivity of primary explosives decreased in the order of AgN 3 = NHN > PbN 6 > MNT > CoHN > BNCP. A possible correlation of spark energy with approximation and assumption has been drawn with thermal, detonation and mechanical properties. The polyvinyl pyrrolidone coated samples followed the same order but interestingly with increased spark sensitivity. An attempt has been reasoning of dielectric nature of the materials or exothermic effects of decomposition products of PVP. The present work also reports the electrostatic spark sensitivity of cap compositions.