A Simple Correlation for Assessment of the Shock Wave Energy in Underwater Detonation

Assessment of underwater detonation (explosion) is important for industrial purposes such as blasting cut of old warship, blasting droll and decoupled charge of blast underwater. Calculation of the shock wave energy requires several expensive experimental data such as the shock wave pressure and the representative time of the process. This work introduces a simple method for reliable prediction of the shock wave energy of composite explosives containing aluminum (Al) and/or ammonium perchlorate (AP), which show non‐ideal behavior. This method is based on the composition, loading density and the ratio of R/m^1/3, where R is the distance between the pressure gauge and charge as well as m is the mass of explosive charge. The measured data for 86 and 21 composite Al/AP explosives are used to construct and test the new model. Statistical parameters including the root mean squared error (RMSE), and maximum of errors (Max Error) of the new model are 0.11 and 0.39 MJ · kg^–1, respectively, which confirm high reliability of the new method. The values of RMSE and Max Error for test set are 0.13 and 0.30 MJ · kg^–1, respectively. Cross validation of the novel model is also used to evaluate its goodness‐of‐fit, goodness‐of‐prediction, accuracy and precision. It is shown that the novel correlation can be applied for pure and composite explosives without Al/AP.     

A Simple Method for Reliable Estimation of the Bubble Energy in the Underwater Explosion

The bubble energy is the main part of the chemical energy of the explosive that is formed upon the propagation of a shock wave through the water for the underwater explosion. A simple method is introduced for reliable prediction of the bubble energy of composite explosives containing aluminum (Al) and/or ammonium perchlorate (AP). It is shown that the bubble energy of composite Al/AP explosives depends on the number of moles of chlorine, carbon, and Al atoms. Experimental data of 56 composite Al/AP explosives are used to construct and test the novel model of the bubble energy. Statistical parameters of the new model, in external validation containing 35 composite Al/AP explosives as the training set, have the values 0.43 and 1.15 MJ · kg^–1 for the root mean squared error (RMSE) and maximum of errors (Max Error) of the new model, respectively. The values of RMSE and Max Error for 21 composite Al/AP explosives as test set are also 0.60 and 2.22 MJ · kg^–1, respectively. Cross validations of the new method corresponding to the coefficients of determination for leave‐one‐out (Q²_LOO) and the fivefold cross validation (Q²_5CV) are 0.8573 and 0.8403, respectively, which confirms goodness‐of‐fit, goodness‐of‐prediction, accuracy and precision of the novel model. It is shown that the novel correlation can be applied for pure and composite explosives, which do not contain Al/AP.     

A New Method for Assessment of Performing Mechanical Works of Energetic Compounds by the Cylinder Test

A new method is introduced for assessment of performing mechanical works of energetic compounds by cylinder wall velocities of CHNOFCl energetic compounds on the basis of the cylinder test. Four suitable decomposition paths are used to evaluate the number of moles of gaseous detonation products per gram of explosive, the average molecular weight of these gases, and the heat of detonation in calories per gram by considering different decomposition products HF, HCl, CO, N₂, H₂O, H₂, and CO₂. For CHNO and fluoro energetic compounds, the predicted cylinder wall velocities of these compounds give more reliable results than one of the best available empirical methods. The predicted root mean square (rms) deviations of cylinder wall velocities of the new model for some chloro explosives at actual radial expansions 0.6 and 1.9 mm are 0.010 and 0.062 km · s^–1, which show high reliability of the new method.     

Detonation Properties of High Explosives Containing Ammonia Borane

Ammonia borane (AB) is used as a combustion agent to improve the properties of high explosives. The detonation velocity (D_v) and detonation pressure (P) of raw high explosives and of samples containing AB were calculated and compared. The detonation properties, impact sensitivities, thermal sensitivities, and thermal decomposition characteristics of high explosives containing AB were also measured. The results indicated that when the AB content was 20 wt‐%, the optimal detonation velocity and detonation pressure were achieved. Both the detonation velocity and detonation pressure of the high explosives containing AB were clearly increased compared with those of the raw high explosives. Moreover, the detonation velocities of high explosives containing AB were 7078 to 7423 m · s^–1 and their density ranged from 1.570 to 1.589 g · cm^–3. The detonation pressure ranged from 34.5 to 37 GPa and the average heat of detonation was 6688 J · g^–1. Furthermore, the impact and thermal sensitivities were 170 cm and 613 K, respectively, whereas a slight change occurred in the thermal decomposition characteristics. These results suggest that AB can serve as a powerful combustible agent in energetic materials and improve the detonation properties and sensitivities of high explosives.     

Reliable Prediction of Shock Sensitivity of Energetic Compounds based on Small‐scale Gap Test through Their Electric Spark Sensitivity

The sensitivity of an energetic compound gives its vulnerability to accidental detonation, which is caused by an unintended stimulus. Shock and electric spark sensitivities of energetic compounds are two important sensitivity parameters for assessment of their safety in working places. Several correlations are introduced for reliable prediction of shock sensitivities of energetic compounds at 90, 95, and 98 % of theoretical maximum density (TMD) according to NSWC using Navy small‐scale gap test through their electric spark sensitivities. For 11 explosives, where experimental data of both shock and electric spark sensitivities were available, the predicted results at 90 % of TMD are compared with the quantum mechanical approach. The root‐mean‐square (rms) deviations of the new and complex quantum mechanical methods at 90 % TMD are 2.38 and 3.95 kbar, respectively, which confirmed the high reliability of the new method. For high explosives with 90, 95, and 98 % TMD, it will be shown that the predicted results of the new method are also much more reliable than one of the best available empirical approaches. A correlation between shock sensitivities on the basis of aluminum gaps with different thicknesses and the pressure required to initiate material pressed to 90 % TMD is also derived.     

The New Descriptors Effective on the Detonation Performance of Aluminized Explosives

The relationship between detonation velocity and the elemental composition of components of aluminized explosives are assessed through quantitative structure-property relationship (QSPR). Here, two new reliable, simple models are proposed for estimating aluminized explosives detonation heat and velocity based on molecular structure by applying QSPR. In this methodology it is assumed that these two detonation parameters can be presented as a function of elemental composition, density and several structural parameters. This new correlation of heat detonation has determination coefficient of 0.930, root mean square deviation (RMSD) of 324.4 and average absolute deviation (AAD) of 446kJ · kg^–1 for 36 aluminized explosives with different molecular structures as the training set. The predictive power of this new correlation is checked through a cross validation method. Statistical parameters reveal relatively good result for this correlation. Also, the determination coefficient of detonation velocity for the other new model is 0.960 and it has 151.1 (RMSD) and 107.9 m · s^–1 (AAD) for 42 aluminized explosives with different molecular structures as training set. Reliability and validity of new correlation investigated (Q²_Ext = 0.948, Q²_LOO = 0.938, and Q²_LMO = 0.937). The good ability of this new model for prediction detonation velocity of aluminized explosives are confirmed.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

Calculation of the composition of detonation products and optimization of dynamic characteristics for mixed explosives

A mathematical model describing the composition of products and dynamic characteristics for the detonation of a multicomponent mixture of condensed explosives was proposed. The model consists of a system of equations with respect to a possible composition and temperature with allowance for the laws of conservation, partial conditions of detailed equilibrium, and semiempirical functional dependence of the energy-release coefficient. The numerical solution of these equations makes it possible to predict a relative impulse, rate, and pressure of detonation of individual explosives and their mixtures and to solve the problem of optimization of the detonation characteristics by composition. The application of the model for the calculation of optimum compositions for standard explosives with the empirical formula C _a H _b N _c O _d F _e was considered.     

Nitro Derivatives of Parabanic Acid as Potential Explosives: A Theoretical Study

This work deals with certain parabanic acid (PA) derivatives because they possess great calculated density (>1.8 g · cm^–3) and high content of nitrogen (26 %). Computed ballistic properties of eight different parabanic acid derivatives are presented. The structures were optimized at the B3LYP/6‐31G(d, p) level. The calculated data for PA are found to be compatible with the experimental X‐ray data. The detonation performance analyses were done using empirical Kamlet‐Jacobs equations. Additionally, detonation products were assigned and power index were calculated. All the compounds considered are powerful candidates for high energy materials.     

Contemplation on Detonation Pressures of Nitramines and ­Nitro Aromatics

A physical model and a mathematical theory for the detonation pressures of explosives materials were developed. The pressure values are expressed as function of the detonation velocity (D) and the average mass (m) of the gaseous products, and are applied for various nitramines and aromatic nitro compounds including nitro pyrimidines and nitro triazines. Some regression equations were obtained and discussed. The pressure values show poor linear dependence on the average mass of the products but good dependence on the detonation velocities alone or Dm. Moreover, for the same Dm value nitramines should produce more pressure than aromatic nitro compounds. This work deals with pressure developed by explosion products and interrelates it with detonation pressure within the constraints of certain assumptions and pays attention to so far unnoticed relationships at least under certain circumstances.     

The Specific Impulse as an Important Parameter for Predicting Chemical High Explosives Performance

The plate dent test is one of the most useful tools used by experimenters for the determination of explosive performance. However, performing the test for every new composition is certainly tedious and time consuming. Hence, the aim of the present study was to introduce a model from which the plate dent performance output could be predicted. Using three set of variables namely, the loading density ρ, oxygen balance Ω and the specific impulse I_sp (calculated according to the [H₂O‐CO₂] arbitrary decomposition assumption), a correlation was derived, which is capable of reliable prediction of the dent depth δ produced on 1018 cold‐rolled steel by a detonating explosive cylinder. Furthermore, the calculated δ values and the well‐known Kamlet‐Jacobs and Keshavarz‐Pouretedal methods were used to estimate the detonation pressure P of CHNOClF‐containing explosives, and the results of each were then compared to experimental/thermochemical code data. The root‐mean square deviation (RMSD) analysis clearly shows that the proposed model is more reliable to predict P than the Kamlet‐Jacobs method especially for fluorine and chlorine‐containing compositions.     

Molecular dynamics and kinetic study of carbon coagulation in the release wave of detonation products

We present a combined molecular dynamics and kinetic study of a carbon cluster aggregation process in thermodynamic conditions relevant for the detonation products of oxygen deficient explosives. Molecular dynamics simulations with the LCBOPII potential under gigapascal pressure and high temperatures indicate that (i) the cluster motion in the detonation gas is compatible with Brownian diffusion and (ii) the coalescence probability is 100% for two clusters entering the interaction cutoff distance. We used these results for a subsequent kinetic study with the Smoluchowski model, with realistic models applied for the physical parameters such as viscosity and cluster size. We found that purely aggregational kinetics yield too fast clustering, with moderate influence of the model parameters. In agreement with previous studies, the introduction of surface reactivity through a simple kinetic model is necessary to approach the clustering time scales suggested by experiments (1000 atoms after 100 ns, 10 000 atoms after 1 μs). However, these models fail to reach all experimental criteria simultaneously and more complex modelling of the surface process seems desirable to go beyond these current limitations.     

Thermodynamic Model for Amorphous Pd(OH)2 Solubility in the Aqueous Na+–K+–H+–OH?–Cl?–ClO 4 ? –H2O System at 25?°C: A Critical Review

Only a limited number of experimental investigations have been conducted to determine hydrolysis constants of Pd(II) or the solubility product of Pd(II) hydroxide, and the reported values differ considerably from each other. No comprehensive reliable thermodynamic model is available for the Pd?COH and Pd?CCl systems. To obtain such a model, thermodynamic data for palladium compounds and complexes with chloride and hydroxide were critically evaluated using the SIT model. These evaluations, in most cases, involved reinterpretation of the original data reported in various publications to produce values of equilibrium constants for various reactions that are consistent with all of available reliable literature data. Final recommended values for solubility products and complexes of Pd(II) with hydroxide and chloride, along with the values for SIT ion interaction parameters, are tabulated.     

Thermodynamic reason for delamination of molecular mixtures under pressure and detonation synthesis of diamond

Diamond clusters containing ∼10⁴ atoms cannot be formed by detonation of explosives if the detonation cloud has a homogeneous composition. Because the volumes and compressibilities of molecular mixtures exceed the additive values, at high pressures the detonation cloud is delaminated into regions with different contents of components, creating conditions for the formation of diamond clusters in the zone of increased carbon content.     

Assembly of Tetrazolylfuroxan Organic Salts: Multipurpose Green Energetic Materials with High Enthalpies of Formation and Excellent Detonation Performance

A series of highly energetic organic salts comprising a tetrazolylfuroxan anion, explosophoric azido or azo functionalities, and nitrogen-rich cations were synthesized by simple, efficient, and scalable chemical routes. These energetic materials were fully characterized by IR and multinuclear NMR (¹H, ¹³C, ¹⁴N, ¹⁵N) spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Additionally, the structure of an energetic salt consisting of an azidotetrazolylfuroxan anion and a 3,6,7-triamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazolium cation was confirmed by single-crystal X-ray diffraction. The synthesized compounds exhibit good experimental densities (1.57–1.71 g cm⁻³), very high enthalpies of formation (818–1363 kJ mol⁻¹), and, as a result, excellent detonation performance (detonation velocities 7.54–8.26 kms⁻¹ and detonation pressures 23.4–29.3 GPa). Most of the synthesized energetic salts have moderate sensitivity toward impact and friction, which makes them promising candidates for a variety of energetic applications. At the same time, three compounds have impact sensitivity on the primary explosives level (1.5–2.7 J). These results along with high detonation parameters and high nitrogen contents (66.0–70.2 %) indicate that these three compounds may serve as potential environmentally friendly alternatives to lead-based primary explosives.     

Theoretical studies on high energetic density nitramine explosives containing pyridine

The insensitive property of explosives containing pyridine is combined with the high energy of nitramine explosives,and the concept of new nitramine explosives containing pyridine is proposed,into which nitramine group with N N bonds is introduced as much as possible.Based on molecular structures of nitramine compounds containing pyridine,density functional theory(DFT) calculation method was applied to study designed molecules at B3LYP/6-31+G(d) level.The geometric and electronic structures,density,heats of formation(HOF),detonation performance and bond dissociation energies(BDE) were investigated and comparable to 1,3,5-trinitro-1,3,5-triazinane(RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX).The simulation results reveal that molecules B and D perform similarly to traditionally used RDX.Molecule E outperform RDX,with performance that approach that of HMX and may be considered as potential candidate of high energy density compound(HEDC).These results provide basic information for molecular design of novel high energetic density compounds.     

An empirical method for predicting detonation pressure of CHNOFCl explosives

This paper describes a new method for prediction of the Chapman-Jouguet detonation pressures of CHNOFCl explosives using the heat of detonation, Q_det, the number of moles of gaseous products of detonation per gram of explosive, α, and the average molecular weight of gaseous products, M. The equation has the form: P_CJ=15.88α(MQ_det)^1/2ρ₀²−11.17, where P_CJ is the Chapman-Jouguet detonation pressure and ρ₀ the loading density. Calculated P_CJ by this procedure show good result with respect to measured detonation pressure for any pure or mixture of ideal and some of less ideal CHNOFCl explosives at ρ₀>0.8 g/cm³.     

Maximum Compaction of Ionic Organic Explosives: Bis(hydroxylammonium) 5,5′‐Dinitromethyl‐3,3′‐bis(1,2,4‐oxadiazolate) and its Derivatives

Within this contribution on bis(oxadiazoles) we report on bis‐hydroxylammonium 5,5′‐dinitro‐methyl‐3,3′‐bis(1,2,4‐oxadiazolate), which (to the best of our knowledge) shows the highest density (2.00 g cm^?3 at 92 K, 1.95 g cm^?3 at RT) ever reported for an ionic CHNO explosive. Also the corresponding bis(ammonium) salt shows an outstanding density of 1.95 g cm^?3 (173 K). The reaction of the 3,3′‐bis(1,2,4‐oxadiazolyl)‐5,5′‐bis(2,2′‐dinitro)‐diacetic acid diethyl ester with different nitrogen‐rich bases, such as ammonia, hydrazine, hydroxylamine, and triaminoguanidine causes decarboxylation followed by the formation of the corresponding salts (cation/anion stoichiometry 2:1). The reactions are performed at ambient temperature in H₂O/MeOH mixtures and furnish qualitatively pure products showing characteristics of typical secondary explosives. The obtained compounds were characterized by multinuclear NMR spectroscopy, IR and Raman spectroscopy, as well as mass spectrometry. Single‐crystal X‐ray diffraction studies were performed and the structures of all compounds were determined at low temperatures. The thermal stability was measured by differential scanning calorimetry (DSC). The sensitivities were explored by using the BAM drophammer and friction test. The heats of formation were calculated by the atomization method based on CBS‐4M enthalpies. With these values and the X‐ray densities, several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code.     

Analytical formulas for calculation of K X-ray production cross sections by alpha ions

In the present study, different procedures are followed to deduce the semi-empirical and the empirical K X-rayX-ray production cross sections induced by alpha ions from the available experimental data and the theoretical results of the ECPSSR model for elements with 20≤Z≤30. The deduced K X-ray production cross sections are compared with predictions from ECPSSR model and with other earlier works. Generally, the deduced K X-ray production cross sections obtained by fitting the available experimental data for each element separately give the most reliable values than those obtained by a global fit.     

Dense Iodine‐Rich Compounds with Low Detonation Pressures as Biocidal Agents

Fifteen iodo compounds and six iodyl compounds with an iodine content between 45.3 and 89.0 % were prepared. The mono, di, and triiodyl compounds were obtained from the corresponding iodo compound by employing Oxone. All the compounds were characterized by IR, ¹H and ¹³C NMR, elemental analysis, and differential scanning calorimetry (DSC). The impact sensitivity was measured by using BAM (Bundesamt für Materialforschung) methodology. Based on the calculated heats of formation and experimental densities, the detonation properties and detonation products were predicted by employing Cheetah 6.0. A total percentage of iodine‐containing species in wt % (I₂, HI, and I in gas phase) ranged from 46.7 ( 21 ) to 88.94 % ( 11 ) was found in the detonation products. The high concentration and easy accessibility of iodine and/or iodine‐containing species is very important in developing materials suitable as Agent Defeat Weapons (ADWs).