Aluminium/tin (IV) oxide thermite composite: sensitivities and reaction propagation

ABSTRACT

Thermites are energetic composites made of metal and oxidizer particles that react according to an exothermic reaction and release large amounts of energy. Many possible metal and oxidizer couples exist in the literature. Here, the performance of the aluminum reducing metal and tin (IV) oxide (SnO₂) combination was reported as a function of the fuel/oxidizer mass ratio. The Al/SnO₂ energetic composite, in stoichiometric conditions, was insensitive to impact, sensitive to friction and extremely sensitive to electrostatic discharge. The combustion velocity was determined to be close to 600 m/s. Changing the stoichiometry affected both the sensitivity thresholds to the friction test (160 N to > 360 N) and flame propagation velocity (480–588 m/s) of the Al/SnO₂ composite. These results are reported for the first time.     

Factors that affect the impact sensitiveness of ammonium nitrate - fuel oil (ANFO) explosives containing aluminium

Abstract

We report the results of a study to investigate the effect of aluminium on the impact sensitiveness of a range of Ammonium Nitrate-Fuel Oil (ANFO) mixtures.

The data obtained indicate that the impact sensitiveness of these mixtures depends on the quantity and type of aluminium, and on the ratio of ammonium nitrate to fuel oil. The magnitude of the dependences is relatively small, however, and all the aluminium-ANFO mixtures examined can be classed as “comparatively insensitive”. We have also shown that the sensitiveness of such mixtures to impact can increase if they contain small quantities of rust or grit as a contaminant.     

Eutectic system of ammonium nitrate with 15 wt% potassium nitrate/ethylenediamine dinitrate/diethylenetriamine trinitrate

Abstract

The phase diagram was determined for the ternary system diethylenetriamine trinitrate/ethylenediamine dinitrate/ammonium nitrate with 15 wt% potassium nitrate (DETN/EDD/AK₁₅). The eutectic mixture (DEAK), containing 40, 35, and 25 wt% AK₁₅, DETN, and EDD respectively, was subjected to small-scale sensitivity and performance tests. The measured P_CJ (223 kbar) from a 4.13-cm-diam, unconfined rate-stick test of the DEAK system agrees with Kamlet-Short-Method (KSM) data calculated at the same pressed density [97.7% of theoretical maximum density (TMD)].

A rate-stick test of EAK at the same charge diameter and pressed density failed, indicating that the addition of the DETN component to the EAK system has reduced the critical diameter of EAK.     

Modelling of CO2 capture and separation from different gas mixtures using semiclathrate hydrates

In this work we present a model for predicting hydrate formation condition to separate carbon dioxide (CO₂) from different gas mixtures such as fuel gas (H₂+CO₂), flue gas (N₂+CO₂), and biogas gas (CH₄+CO₂) in the presence of different promoters such as tetra-n-butylammonium bromide (TBAB), tetra-n-butylammonium chloride (TBAC), tetra-n-butylammonium fluoride (TBAF), tetra-n-butyl ammonium nitrate (TBANO₃), and tetra-n-butylphosphonium bromide (TBPB). The proposed method was optimized by genetic algorithm. In the proposed model, hydrate formation pressure is a function of temperature and a new variable in term of Z, which used to cover different concentrations of studied systems. The study shows experimental data and predicted values are in acceptable agreement.     

Burning Characteristics of Aminoguanidinium 5,5′-Azobis-1H-Tetrazolate/Ammonium Nitrate Mixture—Effects of Particle Size and Composition Ratio on Burning Rate

Ammonium nitrate has been attracting attention over the years as an oxidizer for clean gas-generating agents. Aminoguanidinium 5,5′-azobis-1H-tetrazolate was mixed with ammonium nitrate to improve its burning performance and the burning behavior of the formulations was studied by measuring the linear burning rate. The effects of particle size and composition ratio on the burning rate were studied. It was found that the mixture containing 50% ammonium nitrate by weight was the most promising composition. The particle sizes of fuel and oxidizer do not influence the burning rate.     

Remaking and re-using of double based large caliber powders to be used as industrial explosives

Abstract

A possibility of remaking of double based large caliber gun powders of various shapes was verified, using laboratory-scale granulation in double phased liquid system. Loose composition was prepared from obtained granulation product by mixing with ammonium nitrate. This mixture actually corresponds to the simplest industrial explosive. Its efficiency, energetic and detonation parameters were tested and obtained results were comparable with usual range of industrial explosives parameters. Energetic parameters of one mixture are also introduced.     

Study of continuous velocity probe method for the determination of the detonation pressure of commercial explosives

ABSTRACT

A novel velocity probe, which permits recording the continuous velocities of detonations and shock waves, has been developed based on the transition of operation principle from ionization to pressure-conduction. Using the new probe and the impedance matching method, a series of measuring devices were set up to obtain the shock wave velocities in different inert materials, i.e., water, Plexiglas and paraffin wax. Two test types of powder ammonium nitrate/fuel oil (ANFO), exposed on the ground and tamped in the blast hole, were performed, from which we calculated their detonation pressures, with a density of approximately 0.86 g·cm^?3, ranged from 3.52 GPa to 3.65 GPa, and the adiabatic exponents from 2.24 to 2.30. The results show that the present velocity probe-based method can be used to determine the detonation pressure of commercial explosives conveniently and reliably, which is an important supplement for the testing techniques of explosive performance.     

Structural Effect of Potassium Sulfamate on Synthesis of Ammonium Dinitramide

Potassium sulfamate (PS) is an efficient starting material for the nitration reaction used in the synthesis of ammonium dinitramide (ADN), which is an environmentally friendly high-energy oxidizer for propellants that does not release chlorine-based compounds. PS is a core structure to form dinitramide, -N(NO₂)₂, by taking NO₂^? from nitric acid. In this work, five test batches of PS were prepared using a few solvents including ethanol, methanol, acetone, isopropanol, and their mixtures. The lab-made PSs matched well with the commercial PS in terms of the chemical structure. The use of acetone led to a high recovery of PS up to 97 w/w% and ultimately contributed to the formation of high-purity and (99.2%) and a high yield (57.3%) that are greater than those for commercial PS (87.3% purity and 31.3% yield). Therefore, we proved that the crystallinity and homogeneity of PS influenced the properties of ADN and the synthesis efficiency.     

TATB—Strong basic reactions provide soluble derivatives for a simple,qualitative high explosive spot test

Abstract

Reactions of TATB in aqueous, strongly basic solutions gave metal salts of 1,3,5-trihydroxy-2,4,6-trinitrobenzene (THTNB) also called trinitrophloroglucinol. Thus, we prepared potassium, sodium, and barium salts. The mono- and diammonium salts were prepared by treating THTNB with ammonia and ammonium hydroxide, respectively. Some explosive properties of the salts were evaluated. From the physical characteristics of the salts in various solvents, a spot test was developed for known high explosives (HE) containing TATB.     

Prediction of hydrate formation conditions to separate carbon dioxide from fuel gas mixture in the presence of various promoters

In this study estimation of hydrate formation conditions to separate carbon dioxide (CO₂) from fuel gas mixture (CO₂+H₂) was investigated in the presence of promoters such as tetra-n-butylammonium bromide (TBAB), tetra-n-butylammonium fluoride (TBAF), and tetra-n-butyl ammonium nitrate (TBANO₃). The emission of CO₂ from the combustion of fuels has been considered as the dominant contributor to global warming and environmental problems. Separation of CO₂ from fuel gas can be an effective factor to prevent many of environmental impacts. Gas hydrate process is a novel method to separate and storage some gasses. In this communication, a feed-forward artificial neural network algorithm has been developed. To develop this algorithm, the experimental data reported in the literature for hydrate formation conditions in the fuel gas system with different concentrations of promoters in aqueous phase have been used. Finally, experimental data compared with estimated data and with calculation of efficiency coefficient, mean squared error, and mean absolute error show that the experimental data and predicted data are in acceptable agreement which demonstrate the reliability of this algorithm as a predictive tool.     

A new empirical correlation for prediction of carbon dioxide separation from different gas mixtures

Carbon dioxide (CO₂) emission from different systems such as fuel gas (H₂+CO₂), flue gas (N₂+CO₂), and biogas gas (CH₄+CO₂) is one of the main factors of global warming and environmental problems. So, CO₂ separation from different systems is essential. Low energy consumption, environmental friendliness, and low operational cost of hydrate-based gas separation (HBGS) process show the high potential of this approach in separation of some gases such as CO₂. Hydrate phase equilibrium data are required for designing the separation process. So far numerous models has been proposed for prediction of hydrate formation/dissociation conditions in various systems with/without promoters or inhibitors. This study attempts to present a simple and comprehensive model for fast prediction of hydrate formation conditions to separate CO₂ from biogas, fuel gas, and flue gas systems in the presence of promoters such as tetra-n-butylammonium bromide, tetra-n-butylammonium chloride, tetra-n-butylammonium fluoride, tetra-n-butyl ammonium nitrate, and tetra-n-butylphosphonium bromide. According to the error analysis results, this point can reach the new proposed correlation has better estimation capability in comparison with Sayyad Amin et al. model. On the other hand, hydrate formation temperature can be predicted in the presented correlation with high accuracy.     

A Biodegradable Scale Inhibitor for Oil Well Application

Abstract

Ascorbic acid, an easily biodegradable natural product with an excellent environmental profile, was studied in an oil well downhole condition for inhibiting calcium carbonate scale deposition. Scale inhibition efficiency studied in artificial seawater and formation water mixtures of various proportions through static jar test and dynamic tube blocking tests show its calcite scale inhibition potential at high-temperature wellbore conditions. Investigation made through scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectrometry revealed severe structural anomalies of CaCO₃ crystals and explain the scale prevention mechanism. Its biodegradation rate studied using a UV-visible method in a marine environment is excellent and meets environment requirements. In a sensitive marine environment, ascorbic acid could be deployed as an excellent green chemical for continuous injection into the wellbore to prevent carbonate scale deposition.     

Binary eutectics formed between ammonium nitrate and amine salts of 5-nitrotetrazole I. preparation and initial characterization

Abstract

We have found that both the ammonium salt of 5-nitrotetrazole (ANT) and the ethylenediamine salt of 5-nitrotetrazole (ENT) form eutectics with ammonium nitrate (AN). Initial characterization and small-scale sensitivity tests of CO₂-balanced AN/ANT and AN/ENT formulations were performed; it was found that both eutectics were less sensitive in all tests than pure ANT or ENT, respectively. The phase diagrams of both mixtures were also determined. ANT forms a eutectic with AN that melts at 121°C; the eutectic composition of the AN/ANT system is 78.5 mol% AN. The eutectic temperature and composition of the AN/ENT system were found to be 110.5°C and 87.8 mol% AN, respectively. Thermal stability studies of the eutectics indicate that they are stable below 160°C and that thermal decomposition occurs slowly over a long period of time.

The detonation velocities of both eutectics, measured unconfined at 2.54-cm diameter, were found to be within 95% of those predicted by the Kamlet-Jacobs method assuming ideal behavior.     

The synthesis and characterization of methylene bisoxyamine CH2(-o-NH2)2 salts

Abstract

A large family of energetic salts were made using methylene bisoxyamine, CH₂(-o-NH₂)₂, a dibasic, geminal oxyamine of methane. Single salts including the nitrate, perchlorate, dinitramide, and nitroformate, and doubly protonated methylene bisoxyamine salts, nitrate, perchlorate and bisdinitramide, were all synthesized in good to high yields, from simple acid-base reactions with the corresponding aciforms of energetic anions. All of the salts were characterized by vibrational (IR, Raman), multinuclear nmr (¹H, ¹³C), and DSC studies. The single crystal X-ray diffraction study was carried out on the double perchlorate salt. Initial safety studies (impact and friction), were carried out on most of the new materials, as well as the thermal stability of these salts at 75°C.     

An improved synthesis of 5-amino-3-nitro-1H-1,2,4-triazole (ANTA), a useful intermediate for the preparation of insensitive high explosives

Abstract

Treatment of the ammonium salt of 3,5-dinitro-1H-1,2,4-triazole (ADNT) with hydrazine hydrate gives 5-amino-3-nitro-1H-1,2,4-triazole (ANTA) in greater than 90% yields. In addition to its potential use as an insensitive high explosive, ANTA has been shown to be a useful intermediate for the preparation of other explosives.     

Preliminary Research on Desulfurization of Simulated Diesel Fuel with Peroxotungstate Biquaternary Ammonium Salt/H2O2 System

Abstract

A biquaternary ammonium salt catalyst, chloride-1,4-dibenzyl-diaza-bi-cyclo [2.2.2] octane peroxotungstate (peroxotungstate biquaternary ammonium salt), was prepared, the structure of which was determined through infrared spectrometry, and was applied in desulfurization of simulated diesel fuel. Under the circumstances in which the close ion-pair of biquaternary ammonium cation and peroxotungstate anion was formed, the mechanism of phase transfer catalysis was offered with analyzing experimental process and data. The desulfurization efficiency reached 99.35% when the reaction temperature was 60°C, the reaction time was 20 min, and the molar ratio of peroxotungstate biquaternary ammonium salt to H₂O₂ was 0.015.     

Characterization and Identification of Explosives and Explosive Residues Using GC-MS,an FTIR Microscope,and HPTLC

ABSTRACT

Characterization and identification of explosives and explosive residues collected from different places in India were made using TLC, GC/EI-MS, and GC-FTIR. The explosives used were NG, PETN, TNT, tetryl, RDX, and NH₄NO₃+fuel oil. Quantitative estimation was made using HPTLC. Mass spectra of the samples using selective ion monitoring (SIM) mode based on the relative intensities of the signals X, X + 1 (intensity of the largest fragment X of the explosive, say, RDX [X = 205] was assumed to be 100%, i.e., X = 100%) show no isotopic substitution. The results were confirmed by FTIR spectra. Some physico-chemical aspects of the explosives are discussed.     

Synthesis and Characterization of Tetramethylethylenediamine-Based Hypergolic Ionic Liquids

Four energetic salts (including two ionic liquids) based on 2-(dimethylamino)-N,N,N-trimethylethanaminium and N,N′-dialkyl-N,N,N′,N′-tetramethylethane-1,2-diaminium was prepared and characterized by ¹H- and ¹³C-NMR, infrared and Raman spectroscopies, and elemental analysis. Their physicochemical properties such as melting and decomposition temperatures, density, viscosity, heat of formation, detonation performance, and specific impulse were measured or calculated. With thermal stability up to 200°C, the resulting ionic liquids show densities from 1.02 to 1.19 g cm^?3 and heats of formation from 85.1 to 154.4 kJ mol^?1. Moreover, 2-(dimethylamino)-N,N,N-trimethylethanaminium dicyanamide is hypergolic with the oxidizer (100% HNO₃) and exhibits potential as a green fuel for bipropellants.     

Symmetry,Conjugated System,and N-oxides in 2,4,6-Trinitro-1,3,5-triazine-1,3,5-trioxides: A New Design Concept for Energetic Oxidizers

A new strategy for an energetic oxidizer, 2,4,6-trinitro-1,3,5-triazine-1,3,5-trioxides (TNTATO), was designed by keeping symmetry and conjugation and introducing N-oxides into 1,3,5-triazine. Molecular mechanics (MM) and density functional theory (DFT) were employed to study the crystal structure, infrared (IR) spectrum, electronic structure, thermodynamic properties, gas-phase and condensed-phase heats of formation, detonation performance, and burning rate of TNTATO. The pyrolysis mechanism and thermal stability were predicted by evaluating the bond dissociation energy (BDE) and activation energy. The calculated results indicate that TNTATO has a symmetric hyperconjugation structure, which contributes to its stability. The BDE (210.64 kJ/mol^?1) and activation energy (27.74 kJ/mol^?1) of the weakest bond C3–N8 show that the C–NO₂ bond is the trigger bond during thermolysis. The detonation velocity (8.51 km/s^?1) and detonation pressure (32.69 GPa) are larger than those of 2,4,6-trinitro-1,3,5-triazine (TNTA). TNTATO exhibits better burning properties than ammonium dinitramide (ADN), indicating that TNTATO may be a potential candidate for a highly energetic oxidizer.     

Improved synthetic routes to polynitroheterocycles

Abstract

The preparations of several explosive precursors utilizing oxidative nitration are described. These include 1,3-di-t-butyl-5,5-dinitrohexahydropyrimidine, 3-t-butyl-5,5-dinitrotetrahydro-1,3-oxazine, 2,2-dinitro-1,3-propanediol (ADIOL) and potassium aci-2,2-dinitroethanol. The former pyrimidine and oxazine precursors were nitrolyzed to 1,3,5,5-tetranitrohexahydropyrimidine (DNNC) and 3,5,5-trinitrotetrahydro-1,3-oxazine (TriNOx). ADIOL, a widely used reagent in explosives preparation, was prepared by the trans-ketalization of 2,2-dimethyl-5,5-dinitro-1,3-dioxane. The dioxane was prepared in high yield by the oxidative nitration of 5-hydroxymethyl-2,2-dimethyl-5-nitro-1,3-dioxane. The little known explosive, 1,3,3,5,5-pentanitro-piperidine (PNP), has been prepared from potassium aci-2,2,4,4-tetranitrobutanol and t-butylamine hydrochloride. The vacuum thermal stabilities of DNNC, TriNOx and PNP at 100°C are reported.