Formation Of Explosives Research Articles

Mechanism of hot‐spot formation of emulsion explosives sensitized by hydrogen‐storage glass microballoons

AbstractIn order to investigate the primary factors influencing hot‐spot formation in emulsion explosives sensitized by hydrogen‐storage glass microballoons (GMBs), we conducted impact calculations on hydrogen‐storage GMBs. The calculations focused on tracking two main mechanisms: the brittle collapse of GMBs and the adiabatic compression of internal gas. Various parameters were considered, including loading pressures, initial porosities, gas types, and initial gas pressures. Our findings indicate that the contribution of brittle collapse to hot‐spot formation is negligible, while adiabatic compression emerges as the predominant intrinsic mechanism for hot‐spot ignition in GMB‐sensitized emulsion explosives. Moreover, we observed that the ignition time remains similar for low‐pressure nitrogen and high‐pressure hydrogen. The addition of hydrogen does not result in an increased number of hot‐spots; however, it elevates the energy of each individual hot‐spot, thereby enhancing power delivery. Optimal selection of GMB size is crucial for hot‐spot formation and hydrogen storage. GMBs that are excessively large are prone to shell breakage, while overly small GMBs have limited hydrogen storage capacity. GMBs within the size range of 20 μm to 100 μm are deemed more suitable for emulsion explosives.

Friction-induced temperature rise at energetic β-HMX crystal interfaces: Part II. Simulation of HMX rough surface under dry friction conditions

In this study, the frictional temperature rise of HMX/HMX is investigated with a rough surface sliding on a flat surface by finite element method. The simulation model on the frictional temperature on HMX surface is validated by the in-situ temperature monitoring at moderate friction conditions by tribological experiments and friction-induced ignition of HMX at extreme conditions by friction sensitivity tests. Simulation results reveal that the significance order of frictional parameter that determine the maximum temperature on the asperity of HMX is: friction coefficient > sliding speed > contact pressure. Surface roughness of HMX surface can also affect the frictional temperature rise. Furthermore, a frictional power density of ∼10.8 W/mm2 is determined as the critical security boundary of the friction system when the critical temperature is set to 220 ℃. These findings can provide deep insights into the microscale hot-spot formation and frictional safety mechanisms of explosives.

Selective Synthesis and Characterization of the Highly Energetic Materials 1-Hydroxy-5H-tetrazole (CHN4 O), its Anion 1-Oxido-5H-tetrazolate (CN4 O- ) and Bis(1-hydroxytetrazol-5-yl)triazene.

For the first time, an adequate selective synthesis, circumventing the formation of 2‐hydroxy‐5H‐tetrazole, of 1‐hydroxy‐5H‐tetrazole (HTO), as well as the synthesis of bis(1‐hydroxytetrazol‐5‐yl)triazene (H3T) are reported. Several salts thereof were synthesized and characterized which resulted in the formation of new primary and secondary explosives containing the 1‐oxidotetrazolate unit. Molecular structures are characterized by single‐crystal X‐ray diffraction, 1H and 13C NMR, IR, and elemental analysis. Calculation of the detonation performance using the explo5 code confirmed the energetic properties of 1‐hydroxy‐5H‐tetrazole. The detonation properties can be adjusted to the requirements for those of a secondary explosive by forming the hydroxylammonium (6) or hydrazinium (7) salts, or to meet the requirements of a primary explosive by forming the silver salt 4, which shows a fast DDT on contact with a flame. The sensitivities of all compounds towards external stimuli such as impact, friction, and electrostatic discharge were measured.

Theoretical study of breaking and slipping processes for HMX/graphite interface

Interface dynamics is an important issue to understand the hot spot formation mechanism in high energy explosives. We have studied the interface between octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and graphite. The former is a good performance explosive but has high sensitivity. The latter is the desensitizer for the former. Two kinds of dynamic processes have been investigated: breaking and slipping. The structure evolution, energy variation, and breaking/slipping stresses were calculated. We found that different interface processes lead to different energy dissipation ways. For breaking, it is by surface relaxation. For slipping, it is by interface friction. Both the two ways contribute to the hot spot formation and shock sensitivity of explosives.

A DFT theoretical study of heats of formation and detonation properties of nitrogen-rich explosives

We present density-functional theory predictions and analysis of some properties of synthesized high-nitrogen compounds 3,6-diazido-1,2,4,5-tetrazine (DiAT) and N-oxides of 3,3′-azo-bis(6-amino-1,2,4,5-tetrazine) (DAATO) together with 3,6-di(hydrazino)-1,2,4,5-tetrazine (DHT) and 3,3′-azo-bis(6-amino-1,2,4,5-tetrazine) (DAAT) for which experimental data are available. In this work the reference molecules DHT and DAAT have been studied in order to validate the theoretical approach and facilitate further progress developments for the molecules of interest such as DiAT and DAATO. Geometries of all compounds have been optimized employing the B3LYP density-functional method in conjunction with 6-311++G(3d,3p) basis sets. The energy content of the molecules in the gas phase is evaluated by calculating standard enthalpies of formation, using isodesmic reaction paths. We also include estimates of the condensed-phase heats of formation and heats of sublimation in the framework of the Politzer approach. The obtained results show that DiAT compound has the highest heat of formation (231 kcal/mol) in comparison with those of DHT, DAAT and DAATO molecules. The detonation velocity and pressure have also been estimated for these molecules using the Stine method.

Reliable prediction of electric spark sensitivity of nitramines: A general correlation with detonation pressure

For nitramines, a general correlation has been introduced to predict electric spark sensitivity through detonation pressure. New method uses maximum obtainable detonation pressure as a fundamental relation so that it can be corrected for some nitramines which have some specific molecular structure. There is no need to use crystal density and heat of formation of nitramine explosives for predicting detonation pressure and electric spark sensitivity. The predicted electric spark sensitivities are compared with calculated results on the basis of quantum mechanical computations for some nitramines that latter can be applied. The root mean square (rms) deviations from experiment for new method and the predicted results of complicated quantum mechanical method are 1.18 and 3.49 J, respectively.

Velocity of detonation at any initial density without using heat of formation of explosives

The simplest method is introduced for reliable estimating the detonation velocity of large class of CHNO explosives based elemental composition and specific structural groups. There is no need to use heat of formation and the other experimental data for calculation of detonation velocity in the new procedure. Only elemental composition and the number of special structural groups without using heat of formation of explosive is sufficient for reliable desk calculation of detonation velocity. The results show good agreement with experimental values with respect to computed results obtained by complex computer code using BKWS and BKWR equations of state. Predicted velocities of detonation have root-mean-square (rms) percent deviation of 2.2, 5.9 and 5.3 from experimental data for new method, BKWS and BKWR equations of state, respectively.

A simple method to assess detonation temperature without using any experimental data and computer code

Detonation temperature of C a H b N c O d explosives can be predicted from a, b, c, d and calculated gas phase heat of formation of explosives without using any assumed detonation products and experimental data. Two new correlations are introduced for calculation of detonation temperature of aromatic and non-aromatic explosive compounds so that it is shown here how simply calculated heat of formation by additivity rule and atomic composition are only necessary data for this simple prediction. Calculated detonation temperatures by the introduced correlations for both pure and explosive formulations show good agreement with respect to measured detonation temperatures and complicated computer codes. The average mean absolute error in detonation temperature is within about 7.0%.

New method for predicting detonation velocities of aluminized explosives

A simple procedure for determining detonation velocities of aluminized explosives, which have significantly nonideal behavior, is introduced. It is shown how only the atomic composition and condensed phase heat of formation of explosives, as compared with complicated computer programs, are sufficient for reliable, simple prediction of detonation velocity. Detonation velocities can be predicted by assuming that aluminum powder, based on oxygen content and the different pathways of decomposition of explosives, partially interacts with detonation products. Detonation velocities calculated by this procedure for aluminized nonideal explosives are in good agreement with experimental values, that is, results computed using BKWS-EOS.

Simple determination of performance of explosives without using any experimental data

A simple procedure is introduced by which detonation pressure of C a H b N c O d explosives can be predicted from a, b, c, d and calculated gas phase heat of formation of explosives at any loading density without using any assumed detonation products and experimental data. It is shown here that the loading density, simply calculated heat of formation by additivity rule and atomic composition can be integrated into an empirical formula for predicting the detonation pressure of proposed explosives. Calculated detonation pressures by the introduced method for both pure and explosive formulations show good agreement with respect to measured detonation pressure over a wide range of loading density. The deviations are within about experimental errors.

New method for estimating the heat of formation of CHNO explosives in crystalline state

For CHNO explosives, a new correlation is derived, which has the form Q c o r r /cal = 0.196T a d /K + 755 in the range Q c o r r > 1100 cal between Kamlet's corrected heat of detonation, Q c o r r , and approximate detonation temperature, T a d . The semi-empirical PM3 procedure is used for calculating the approximate heat of formation of the explosive in the gas phase, which is required for the computation of T a d . In calculating Q c o r r , it is assumed that the decomposition products of any CHNO explosives consist of CO, CO 2 , H 2 O, N 2 , H 2 , solid carbon, and in the next step the carbon monoxide is converted to carbon dioxide and solid carbon. The calculated Q c o r r can be used for the determination of the heat of formation of any CHNO explosives in the solid state.

Societies and Academies

PARIS Academy of Sciences, August 1.—M. Jamin in the chair.—The following papers were read:—On the formation of tails of comets (second note), by M. Faye. Herschel, Arago, Delaunay, and other astronomers did not thoroughly study the tails of comets, hut Newton had already given a quite sufficient explanation of the phenomena. The tail is nothing else—he maintained than the result of a continual emission of molecules from the head of the comet. It is very much like; the tail of smoke emitted by a running locomotive, its outer end being lost in space, and the inner one continually receiving a new supply of molecules. M. Roche, who has made the necessary calculations, taking account of the repulsive force M. Faye advocates, has worked out all those shapes of tails which we witness in reality.—On the equivalence of quadratic forms, by M. Jordan.—On a modification of the electric lamp, by M. Jamin, being the result of observations on the electric light in vacuum, and in closed vessels containing various gases.—On the perchloric acids, by M. Berthelot.—On the travels of Moncatch-Apé, by M. Quatrefages. This American Indian undertook a journey to the north-western coasts of America at the beginning of last century, in search of the origin of his race; whilst on this coast he learned and witnessed that it was visited every year by white men with long black beards, and M. Quatrefages proves that these men were originally from the Loo Choo islands.—On the first meteorological, topographical, and hydrographical observations at the future Panama canal, by M. de Lesseps. Several maps of the coast are prepared, and a meteorological station is opened at Colon.—On the application of electromotive power and of M. Planté's secondary piles to the direction of aërostats, by M. Tissandier. In an aërostat which has a volume of 2200 litres, 3·50m. long, with a diameter of 1·30m., and can raise a weight of 2 kilogrammes, having a Siemens machine which weighs 220 grammes, and a secondary couple of 1300 grammes, the propulsory helix makes six and a half revolutions per second, and the balloon acquires a speed of 1 metre per second for forty minutes. The small Siemens machine, with three elements, produces the work of 1 kilogrammetre.—The elements of comet c of 1881 (Schäberle), by M. Bigourdan, as deduced from observations at Vienna on July 18, and at Paris on July 23 and 28. Its brightness, which is still increasing, will be on August 23 seventeen times as much as it was on July 18.—Spectroscopical observations on the comets b and c, 1881, by MM. Thollon and Tacchini.—On the lengths of spectral bands given by compounds of carbon, by M. Thollon.—On the constitution of comets, by M. Prazmowski.—On the theory of trilinear forms, by M. Le Paige.—On the influence of pressure on dissociation, by M. Lemoine.—On the heat of formation of explosives, by MM. Sarrau and Vieille.—On oxycyanides of lead, cadmium, and mercury, by M. Joannis.—On the heat of combustion of heptane and of hexahydrotoluene, by M. Louguinine.—Third note on the magnesia industry, by M. Schlösing.—A contribution to the study of the transmission of tuberculosis, by M. Toussaint. The juices of animals which have had tuberculosis transmit the disease with very great ease, even when submitted to a high temperature, but especially when employed uncooked.—On the injection of the virus of rabies into the circulation, by M. Galtier. It seems to prevent infection.—On hemeralopia and on the functions of the visual purple, by H. Parinaud.—On the applications of electromotors, by M. Trouvé.

Societies and Academies

PARIS Academy of Sciences, July 25.—M. Wurtz in the chair.—The following papers were read:—On the comet b of 1881, by M. Mouchez. The result of M. Oudemans' search among the Dutch Colonial Archives in South Africa is that the comet of 1881 is probably not that of 1807, but seen now for the first time.—Determination of the horizontal and lateral flexure and the flexure of the instrumental axis of the meridian circle of Bischoffsheim, by means of new apparatus, by MM. Lœwy and Perigaud.—On the equivalence of quadratic forms, by M, Jordan. —On chlorhydric ether of glycol, by M. Berthelot.—Anthracic vaccination; résumé experiments made at Lambert, near Chartres, to test the method of M. Pasteur, by M. Bouley. The essence of the test consisted in inoculating vaccinated sheep with natural virus (anthracic blood from a sheep which died of the disease) instead of that prepared by processes of culture. The efficacy of the vaccination was fully demonstrated.—On the irreducible covariants of the binary quantic of the eighth order, by Prof. Sylvester.—Parabolic elements of the comet b 1881, by M, Bigourdan.—Observations of Schssberle's comet (c 1881) at Paris Observatory, by M. Bigourdan; also by MM. Henry. —Considerations on the forces of nature; inadmissibility of the hypothesis proposed by M. Faye to explain the tails of comets, by M. Picard. Whatever the nature of the repulsive force it can only be proportional to masses, not to surfaces, for ideal pressure on surfaces only arises from effective action on masses. No interposed matter can weaken or arrest its action, for the etherised medium penetrates all bodies. The action is propagated, not successively but instantaneously, being due not to an undulatory motion, but to shocks of etherised atoms and ponderable molecules, like gravitation; hence on a point in motion it is exerted in the same direction as the attraction exercised by the ponderable mass of the sun.—Remarks on the calculation of relative perturbations, according to M. Gyldén's method, by M. Callandreau.—Hemihedral crystals with inclined faces as constant sources of electricity, by MM. Jacques and Pierre Curie. A plate suitably cut in such a crystal and placed between two sheets of tin forms a condenser which becomes charged when it is compressed. The authors give an absolute measure of the quantities of electricity liberated by tourmaline and quartz for a determinate pressure. It is|shown how the instrument may serve in comparison of charges and capacities.— Determination of the angular distance of colours, by M. Rosenstiehl. He shows that three colours previously referred to, viz. orange, the third yellow-green, and the third blue, have the characters of a triad (that is, mixed in equal intensity, they produce the sensation of white). All the colours which occupy the angles of an inscribed equilateral triangle have the same properties.—Electric stopcock; transformation, transport, and use of energy, by M. Cabanellas —On the heat of formation of explosives, by MM. Sarrau and Vieille. When an explosive is decomposed the heat liberated is equal (according to thermodynamics) to the excess of the heat of formation of the products over the heat of formation of the explosive. Hence, knowing, in a given case, the heat liberated by decomposition, and the composition of the products of the reaction, the heat of formation may be arrived at. The authors have applied the method to the principal explosives, and will shortly give the results.—Industry of magnesia (continued), by M. Schlcesing. He treats sewage matter with phosphate of magnesia, obtaining the phosphoric acid from natural phosphates of lime, and the magnesia from sea-water or water of salt marshes (it is precipitated by slaked lime). He produces a sort of vermicelli of lime, which gives a porous magnesia, on which the acid liquid acts easily.—On some reactions of morphine and its congeners, by M. Grimaux.—On a new process of vaccination of chicken cholera, by M. Toussaint. He inoculated fowls with blood of rabbits which had died of septicemia (or with matter cultivated from it), and the effects were those of an attenuated virus, which made the fowls refractory to cholera.—On a volcanic breccia capable of being utilised as an agricultural manure, by M. Carnot. The rock (from l'Herault) contains notable amounts of iron, lime, potash, and phosphoric acid.—Boric acid; its existence in salt lakes of the modern period, and in natural saline waters (second note), by M. Dieulafait.—On the extraordinary temperature of July, 1881, by M. Renou. It rose to 38°.4 on the 19th at the Park Observatory, a degree never experienced in Algiers, the Antilles, and Cayenne.