Showing papers in "Propellants, Explosives, Pyrotechnics in 1978"

Relation entre la Structure Electronique et la Sensibilité au Choc des Explosifs Secondaires Nitrés-Critère Moléculaire de Sensibilité. I. Cas des Nitroaromatiques et des Nitramines

Abstract: Resume Cet article est le premier d'une serie ou l'on tente d'etablir une relation entre la sensibilite au choc des explosifs secondaires nitres et leur structure electronique. On y met en evidence, dans le cas des nitroaromatiques et des nitramines, le rǒle privilegie lors de la generation de la detonation d'une liaison R–NO2 de la molecule. L'examen des modifications subies par la distribution electronique de cette liaison apres absorption d'energie permet de definir un parametre parfaitement correle a l'echelle des sensibilites experimentales. La validite de ce parametre en tant que critere de sensibilite accredite, a posteriori, l'existence avant la detonation d'un etat excite.

Role of Additives in Combustion Waves and effect on stable combustion limit of double‐base propellants

Abstract: The effect of additives on the flame structures and the burning rates of double-base propellants have been examined by means of photographic observations and temperature profile measurements. The additives used for this study are lead salicylate (PbSa, 2%), nickel (Ni, 1%), ammonium perchlorate (AP, 30%), and cyclotetramethylene tetranitramine (HMX, 30%). The addition of PbSa increases the burning rate, but does not improve the flame temperature characteristics. The addition of Ni increases the flame temperature significantly at pressures below 30 atm. The Ni acts as a catalyst to promote the flame reaction while it does not act as a burning rate modifier. The additions of AP and HMX increase the thermal performance of the propellant system, however, the HMX does not improve the stable combustion limit of the rocket motor at low pressures. The addition of Ni or AP is found to increase the flame temperature at pressures below 30 atm, and the stable combustion limit is lowered to below 3 atm.

A Photographic Study of the Combustion Zones of burning double base propellant strands

Abstract: The combustion zones of doublebase propellant strands and their dependence on pressure were studied by different photographic techniques to get new information on the action of ballistic modifiers. Photos of short exposure time were taken from the foam, dark and flame zones. The extinguished burning surface was studied by optical and scanning electron microscopes. A detailed picture on the production of carbonaceous material on the burning surface was obtained.

A Reappraisal of Silver Fulminate as a detonant

Abstract: Summary The preparation and properties of silver fulminate have been examined to assess its potential for use as a primary explosive. It is an extremely effective detonant but does not appear promising as a stab-sensitive material. It is concluded that its extreme sensitiveness and the hazards and difficulties associated with its preparation render it unsuitable for military applications. It does find commercial use in the manufacture of toys and crackers when it is normally handled exclusively in small quantities and in the wet state.

Thermal Reactivity of Methylammonium Nitrates

Abstract: The reactivity of the mono-, di- and trimethyl-ammonium nitrates to heat has been studied using differential thermal analysis, thermogravimetry and mass spectral analysis The decomposition temperature of these compounds increases in the order $CH_3NH_3NO_3 > (CH_3)_2NH_2NO_3 > (CH_3)_3NHNO_3$ The activation energies have been determined employing isothermal decomposition technique Mass spectrometric investigation shows that the extent of decomposition increases with increasing substitution on the nitrogen atom Possible reasons for such behaviour have been explored

The Propagation of Blasts from Solid Explosives to two-phase media

Abstract: The aim of this investigation is to determine the influence of the energy release from a combustible two-phase media on the blast wave generated by an explosive charge, during the first stages of the process. For this purpose ball charges of “Composition B” were detonated in air, in pure nitrogen containing suspended solid particles of carbon, and in pure oxygen containing particles of aluminum and carbon. The blast wave's velocity was measured in all the media using fast frame camera 300,000 f.p.s. and streak photography at 2 mm/μs. The influence of release or absorption of energy by the medium was investigated by comparing experiments done in inert media with those conducted in combustible media while other parameters are kept constant. Kozorezov's triple isentrope model was compared to the results, and good agreement is found. The article contains detailed information on the experiments and the calculations performed.

Strength Testing of Explosives by Underwater Detonation

Abstract: Shock wave energy and bubble energy for different explosives have been measured in underwater experiments. A method to determine bubble energies in cases where the free water surface and bottom boundary disturb the bubble oscillation has been developed. The shock energy loss when the primary shock wave travels from the charge to the gage resulting in heating of the surrounding water has been estimated by correlation with data derived from detonation calorimeter experiments for some explosives. Comparison of the measured total expansion work with data from thermodynamic computer calculations show good agreement for many oxygen balanced explosives, but poor agreement for explosives with a large oxygen deficit. For explosives of the ANFO type there is a considerable effect on expansion work by booster size, charge size, and shape.

The State of the Detonation Products of Solid Explosives

Abstract: The polytropic equation, together with the detonation relations, provides practicable values for all the quantities characterizing the detonation products of solid, high explosives apart from the temperature. Its application, however, is restricted to material at absolute zero, that is to solids possessing purely potential energy. Thus polytropic detonation products have the characteristics of solids although their state of aggregation is gaseous. In fact the polytropic equation can be derived by assuming a solid under an internal, expansive pressure sufficient to break all atomic bonds. In terms of the Debye theory this represents an approximation which is valid in the absence of the thermal energy contribution from atomic vibrations. This requirement is satisfied by the detonation products of solid explosives of sufficiently high density since their heat of detonation is completely absorbed by the breakage of atomic bonds or the sublimation of the atomic lattice. The sublimation process in the course of the reaction also allows the Chapman-Jouguet temperature of the detonation products to be determined from the equilibrium between the phases. In addition the fracture theory provides material data which assign a metallic character to the polytropic detonation products and indicate that they form a conducting plasma.

Testing of Low‐Sensitivity Explosives from the safety point of view

Abstract: The world's explosive industry is changing. New non-nitroglycerin explosives of different sensitivities and physical characteristics are being developed. Many slurry explosives are mixed and pumped at elevated temperatures, and powder explosives will often be exposed to higher than ambient temperatures in the process equipment. explosives? Is it possible that different fractions of a powder explosive have different sensitivities? Which test methods can we use to evaluate sensitivity? Will the results tell us something we can apply in practical safety evaluations of explosives and process equipment? These are some of the questions we have asked. In this note some results from our work on sensitivity testing are reported. What effect has temperature on the sensitivity of “insensitive” explosives? Is i t possible that different fractions of a powder explosive have different sensitivities? Which test methods can we use to evaluate sensitivity? Will the results tell us something we can apply in practical safety evaluations of explosives and process equipment? These are some of the questions we have asked. In this note some results from our work on sensitivity testing are reported.

Untersuchung der Detonationsschwaden verschiedener Explosiv- und Sprengstoffe

Abstract: In einem Sprengkessel wurden verschiedene Mengen an Nitropenta, Hexogen, Tetryl, Polyvinylnitrat und Ammonit 1 sowohl in Argon- Atmosphare als auch unter Luft zur Detonation gebracht. Die hierbei gebildeten Reaktionsschwaden wurden gaschromatographisch analysiert. Der Gehalt an Stickoxiden wurde unter Verwendung eines NOx-Chemolumineszenz-Analysators ermittelt. Es zeigte sich, das bereits eine geringe Menge Luft (4 Vol.%) in der Inertgasatmosphare den NO-Gehalt der Detonationsschwaden deutlich erhoht. Eine noch starkere Bildung von NO wird beim detonativen Zerfall der Explosivstoffe in Luft beobachtet. Die experimentellen Ergebnisse werden diskutiert und mit Resultaten verglichen, die unter Verwendung eines thermodynamischen Rechenprogrammes erhalten wurden.

Performance Optimization of Metallized Solid Propellants

Abstract: The object of this paper is to present a method for determining, for a typical metallized solid propellant system, the optimum combination of the reactants so as to arrive at a composition which can yield the maximum specific impulse. A direct approach of this kind for optimization of propellants does not appear to have been attempted so far. The optimization is sought to be carried out by expressing the theoretical specific impulse of the propellant under frozen flow conditions as a function of the different variables involved and maximizing the same, subject to the usual linear and non-linear constraints of mass balance, mass action, pressure balance, energy conservation and entropy conservation. The gradient projection technique due to Rosen has been adopted for carrying out this optimization. The method was programmed on the IBM 360/Model 44 Computer in FORTRAN IV language and the results of the computations for a typical metallized solid propellant system are presented in the paper. The investigations reveal that the gradient projection technique can be a useful computational device for determining the optimum composition and the corresponding performance parameters of propellant systems containing a large number of reactants and products with or without condensed phases.

Detonability of Slurry Blasting Agents

Abstract: The detonability of slurry blasting agents is characterized by their critical detonation diameter and their cap sensitivity A quick method using conical charges permits the critical detonation diameter to be measured The influence of density on the detonability was examined Density of the slurry was varied by gassing before shotfiring or by compressing the slurry on firing The results are different according as the slurry contains an explosive or non-explosive sensitizer

Is ammonium perchlorate in composite solid propellant under strain

Abstract: Thermal decomposition of ammonium perchlorate-polystyrene propellant as a function of oxidizer loading has been found to behave in a fashion analogous to the thermal decomposition of ammonium perchlorate as a function of precompression pressure. It has been argued that the above behaviour of the propellant is due to the strain caused by the binder film on ammonium perchlorate contained in the propellant matrix. The presence of strain has been demonstrated independently by x-ray diffraction peak and infrared peak broadening and strain energy measurements.

Erfahrungen mit Methoden zur Einordnung der Deflagrationsfestigkeit von Wettersprengstoffen

Abstract: Zur Ermittlung der Deflagrationsfestigkeit von Wettersprengstoffen hoherer Sicherheitsklassen wird in der Bundesrepublik Deutschland eine Variante des von Audibert und Delmas vorgeschlagenen Verfahrens benutzt (geschlossenes Stahlrohr mit Entlastungsduse). Dabei wird die Deflagrationsneigung des Sprengstoffs unter Druck- und Warmestau in einer Kohlenstaubumgebung bestimmt. Die Einleitung der Deflagration erfolgt durch einen definierten Anzundsatz. Die Druck- und Warmestau-Bedingungen werden durch eine Duse wahlbaren Durchmessers vorgegeben. Bei den nach diesem Verfahren gepruften und zugelassenen Wettersprengstoffen ist in der Praxis seit 1972 kein Fall einer Deflagration bekannt geworden.

Thermal Decomposition of Ammonium Perchlorate containing a polymeric additive

Abstract: Thermal decomposition of ammonium perchlorate (AP) containing different concentrations of a polymeric additive such as polyvinyl pyrrolidone (PVP) has been studied by the technique of differential thermal analysis (DTA). The decomposition products have been identified by means of a mass spectrometer. The results of these two experiments suggest strong interaction between AP and PVP in the solid state.

Laboratory and Field Investigations of Shotfiring Fumes of mining explosives in Poland

Abstract: Detonation products of basic explosives like ammonium nitrate, permitted Metanit D 2 and nitroglycerin-Barbaryt A were analysed for O2, CO2, CO, CH4, H2, NO2 and N2 and the shotfiring properties studied. The tests were carried out under laboratory conditions and in shotholes drilled underground in the mine, in coal and in stone.

EXTEST International Study Group for the standardization of the methods of testing explosives. (Formerly European commission for the standardization of the tests of explosives)

Abstract: The report gives an account of the discussions and the agreements reached during the 7th meeting of the Commission together with the full texts of the 18 technical papers presented to the meeting. Recommended standards and testing procedures were finally approved for the following: Ballistic mortar Transmission of detonation of ion-exchanged explosives Test detonators with 0.6 g and 0.25 g PETN Method of testing the initiating strength of detonators. The following new themes were included in the plan for the next period of work of the Commission: Toxic fumes from explosives in blasting Initiation and stability of detonation of slurry and water gel explosives under different conditions Sensitivity of slurry and water gel explosives The underwater explosion test Deflagration and transition from deflagration to detonation. The Commission agreed on a change of its name. The new name will be: „EXTEST International Study Group for the Standardization of the Methods of Testing Explosives”. A suggestion for the Commission to seek a form for association with other international corporative bodies such as the International Organization for Standardization (ISO), suitable for furthering the objectives of the Commission, was discussed and will be further investigated. The next meeting of the Commission will be in 1978 in Czechoslovakia.

Methode zur Bestimmung des Zündvermögens von Sprengkapseln und Sprengzündern

Abstract: Es wird uber eine Prufmethode der Fa. Dynamit Nobel AG berichtet, bei der mit einer einzigen Prufmischung die gesamte Skala der Zundstarken der technisch verwendeten Sprengkapseln und Sprengzunder erfast werden kann. Der Aufbau der Prufanordnung, das Herstellen des Prufsprengstoffs und der Prufladung werden beschrieben, Versuchsergebnisse werden diskutiert.

Utilisation de la Méthode par Immersion pour la Détermination de l'Energie dans les Gaz d'Explosion

Abstract: C'est par une simple mesure seismographique que l'on obtient la periode de pulsation de la bulle gazeuse formee sous l'eau lors de l'explosion et en resultant par calcul l'energie dans les gaz d'explosion. Les energies dans les gaz d'explosion pour quelques explosifs industriels sont evaluees.

Empfindlichkeit der Sprengstoffe gegenüber Zündern und Zündstärke von Zündern als unsymmetrisch‐reziproke Größen

Abstract: Im Bereich chemisch einheitlicher detonationsfahiger Stoffe konnen auf Grund experimenteller Ergebnisse die Empfindlichkeit der Sprengstoffe gegenuber Zundern (z. B. als Ergebnisse von Versuchen mit MeGkapseln) einerseits und die Zundstarke von Zundern andererseits eindeutig und allgemein als reziproke Grosen aufgefast werden. Auf der Seite der Sprengstoffe spielt in diesem Zusammenhang als Variable neben bestimmten Sprengstoff-Eigenschaften die globale Dichte der Sprengkorper eine ausgepragte Rolle. Der Dichteeinflus auf die Zundempfindlichkeit verhalt sich dabei gerade umgekehrt wie der Dichteeinflus auf die durch den reziproken kritischen Durchmesser festgelegte Detonationsempfindlichkeit. Geht man auf der Seite der Sprengstoffe zu heterogenen Zwei oder Mehrkomponenten-Mischungen uber, wobei es sich um Komponenten verschiedener Reaktivitat (ggf. einschlieslich inerter Komponenten) handelt (Gewerbliche Sprengstoffe), dann findet sich die reziproke Beziehung im Sinne einer Unsymmetrie mehr oder weniger verandert. Entscheidend dafur ist in erster Linie die Art, Menge und strukturelle Einordnung der hochsensiblen Komponente. Ruckschlusse auf die Aussagekraft verschiedener Verfahren Zundstarke-Messung an Zundern und auf die Frage der Schaffung durch Absolutangaben definierbarer Skalen fur Initiierungs-Sensibilitat und Zundstarke werden dargelegt.

The assay of hydrazine mononitrate as a base in acetic acid

Abstract: Hydrazine mononitrate has been determined as a base by non-aqueous titration in glacial acetic acid. The titrant was 0.05 N perchloric acid in glacial acetic acid which must be prepared without acetic anhydride. Small amounts of water increase the solubility of hydrazine nitrate, but reduce the sensitivity of the method.

Génération et Repérage d'un Signal Lumineux Bref

Abstract: Resume On presente une methode simple de generation et d reperage d'un signal lumineux. Ce signal est obtenu en ionisant un petit volume d'argon par une onde de choc forte. Il est repere dans le temps a l'aide d'un signal electrique provoque par la polarisation d'un materiqu dielectrique traverse par cete meme onde de choc. Ce dispositif est utilise pour determiner le temps de retard d'un pyrometre optique a court temps d reponse.

A Numerical Study of Explosive Heating due to Projectile Impact

Abstract: A finite difference Eulerian computer code with some very useful Lagrangian features is employed to study the impact of a projectile on a heavily confined, inert, solid explosive. Temperature rise due to shock compression and plastic deformation in both the explosive and the metal confinement is estimated. It is concluded that in situations where the shock is weak and the explosive does not initiate shortly after the projectile impact, the possibility of it so doing, due to plastic deformation, at a later time cannot be discounted.

Experimental investigation into the L* instability of double base rocket propellants

Abstract: In a continuous joint research program, the Department of Aerospace Engineering of DUT and the Technological Laboratory TNO investigate unstable combustion of solid rocket propellants. Some results of this research program are discussed here. The oscillatory combustion phenomenon is discussed qualitatively, and the interaction between the acoustics of the cavity and the pyrolysis of the propellants is explained. For the investigation of the low-frequency unstable combustion, a special device, the L* burner, is very suited. A description is given of the two L* burners of different size, which were used in the experiments discussed here. Reproducible ignition is of the utmost importance to conduct these tests. Various ignition methods have been tried and are described together with a very successful one, which was evaluated and finally selected. The experimental results of JPN and ARP propellant experiments are discussed extensively. Oscillatory combustion as well as chuffing has been observed, and it turns out that both phenomena are related to the L* and pressure. As L* burners of different sizes were used, it was possible to estimate the damping, and hence the propellant growth constant. On the basis of the results of these experiments it seems most likely that the damping is volumetric. It has been discovered that for a very large pressure range (∼ 3 MPa) the frequency of the oscillations is linearly dependent on the mean pressure, while at low pressures (<1 MPa) oscillations with a higher frequency, also dependent on the mean pressure, are observed. These observed pressurefrequency correlations are the same for the two L* burners of different size, and hence it may be concluded that these correlations are not affected by the dimensions of the motor cavity.

Ways of Reducing the Deflagration Tendency of ion‐exchanged permitted explosives

Abstract: This work considers possible ways of reducing the deflagration tendency of ion-exchanged permitted explosives based on new experimental data on the inhibition of ignition of methane-air mixtures and on the cornbustion of condensed systems. The mixtures contained the nitrates or perchlorates of the alkali metals as oxidizers together with ammonium chloride, oxalate, sulphate or phosphate as fuel. They had a zero oxygen balance. The effect of adding 12% of gelatinized nitroglycol was also investigated. The lower pressure limit and the burning rate were chosen as parameters to characterize the deflagration rendency. They were in a constant pressure bomb over the pressure range 0.1 MPa to 100 MPa using a method described previously. It is shown that the lower pressure limit is higher and the burning rare lower for mixtures containing ammonium oxalate than for analogous mixtures but with ammonium chloride. The lower pressure limit is also higher for mixtures based on potassium perchlorate. The calculated explosive characteristics and the burning parameters of the mixtures investigated arc reported. Reasons for the higher deflagration tendency of the mixtures containing ammonium chloride are discussed.