Showing papers in "Propellants, Explosives, Pyrotechnics in 1983"

Blast Waves in Free Air

Abstract: Simple equations are given which can be used for calculating the approximate values of peak overpressure and positive phase impulse of blast waves generated by the detonation of military high explosive charges in the free atmosphere. To the practitioner, these equations may be useful in the quick and simple design of protective systems, or in calculating the amount of explosive required to achieve a certain desired effect. Moreover, an outline is given of the derivation of simple equations for the damaging effect of blast waves as a function of distance and charge weight. A useful formula, which had been given by Westine, encompasses the following three main causes of a damaging effect: peak overpressure, if the blast duration is long as compared to the natural vibration period of the target structure; pressure impulse, if the blast duration is short as compared to the natural vibration period of the target structure; product of peak overpressure multiplied by impulse in the intermediate range, i.e., if the duration of the pressure pulse is comparable to the natural vibration period of the target structure.

Improved formulas for velocity, acceleration, and projection angle of explosively driven liners

Abstract: Improved one-dimensional formulas for both the direction and magnitude of the velocity of explosively driven liners are developed. First, an analytical formula for the direction of motion of the liner under unsteady conditions is derived. This new formula is compared with both two-dimensional calculations and experimental data for both shaped-charge and exploding cylinder geometries. The new formula is more accurate than the classical steady-state Taylor-angle formula for these cases. Next, for implosive geometries, a new formula for the fully accelerated liner velocity is given. Since the standard Gurney approach does not apply to imploding geometries, a modified approach was adopted. Results agree well with two-dimensional code results for a wide range of explosives and geometries. Also, the velocity history is shown to follow an exponential law, and a useful formula for characteristic metal acceleration time was developed. Verbesserte Formeln fur die Geschwindigkeit, Beschleunigung und den Projektionswinkel von explosiv beschleunigten Liners Verbesserte eindimensionale Formeln sowohl fur die Richtung als auch fur die Grose der Geschwindigkeit von explosiv beschleunigten Liners werden entwickelt. Zuerst wird eine analytische Formel fur die Bewegungsrichtung des Liners unter veranderlichen Bedingungen abgeleitet. Diese neue Formel wird verglichen sowohl mit zweidimensionalen Berechnungen als auch mit experimentellen Daten und zwar fur Hohlladungs- und explodierende Zylindergeometrien. Die neue Formel ist genauer als es die klassische stationare Taylor-Winkelformel fur diese Falle ist. Weiterhin wird fur implosive Geometrien eine neue Formel aufgestellt fur die voll beschleunigte Linergeschwindigkeit. Da die Stan-dard-Gurney-Naherung nicht auf implodierte Geometrien anwendbar ist, wird eine modifizierte Naherung angenommen. Die Ergebnisse stimmen gut mit den Resultaten des zweidimensionalen Rechenprogramms fur einen weiten Sprengstoff- und Geometriebereich uberein. Auserdem wird gezeigt, das die Geschwindigkeits-Historie einem Exponentialgesetz folgt, und es wird eine brauchbare Formel fur die charakteristische Metallbeschleunigungszeit entwickelt. Formules ameliorees pour le calcul de la vitesse, de l'acceleration et de l'angle de relevement des revětements projetes par explosif On a mis au point des formules monodimensionnelles ameliorees pour calculer la direction et la grandeur du vecteur vitesse de revětements projetes plar explosif. En premier lieu on etablit une expression analytique qui donne la direction du vecteur vitesse du revětement pour differentes conditions de projection. Cette nouvelle formule est comparee aux resultats des calculs bidimensionnels et aux donnees experimentales obtenues avec des charges creuses et des charges cylindriques. La nouvelle formule fournit pour ces cas des resultats plus precis que la formule classique de Taylor pour l'etat stationnaire. En outre on indique une nouvelle formule pour les geometries implosives qui fournit la vitesse du revětement a pleine acceleration. L'approximation classique de Gurney ne s'appliquant pas aux geometries implosives, on adopte une approximation modifiee. Les resultats concordent bien avec ceux du code de calcul bidimensionnel pour une large gamme d'explosifs et de geometries. On montre egalement que l'evolution temporelle de la vitesse suit une loi exponentielle et on developpe une formule pratique pour calcuculer le temps d'acceleration caracteristique des metaux.

Structure and properties of the potassium hydroxide‐dinitrobenzofuroxan adduct (KDNBF) and related explosive salts

Abstract: The structure of KDNBF was previously shown to be as in formula (2), Mn+ = K+, a Meisenheimer complex of 4,6-dinitrobenzofurazan-1-oxide and potassium hydroxide(3,4,5). The corresponding sodium, silver and barium salts are shown to have identical molecular structure to KDNBF on the basis of IR and NMR spectral data. Explosive properties of the four salts were determined. The barium salt is substantially less sensitive to thermal, electrostatic and mechanical stimulae relative to the other three salts.

Performance Properties of Commercial Explosives

Abstract: The aquarium test is a proven means of obtaining nonidial performance property data for commercial blasting agents. Optical data on the detonation velocity, shock wave in water, and expansion rate of the pipe enclosing the detonation products (in combination with the equilibrium thermodynamic chemistry code BKW) give the C-J state and degree of chemical reaction at the detonation front, as well as information on additional chemical reaction that occurs as the detonation products expand. Specific explosive systems that are studied are ammonium nitrate-fuel oil mixture (ANFO), aluminized ANFO, flaked trinitrotoluene (TNT), and several other commercial products in 10-cm-diam and 20-cm-diam pipes of Plexiglas and clay. Experimental shock pressure data are obtained with lithium niobate transducers placed in the water surrounding the explosive charge. These data show that the addition of ∼ 100-μm aluminum particles to ANFO significantly increases the initial peak shock pressure delivered to the surrounding medium. Peak shock pressures in the water, calculated from the shock-wave orientation, are also useful in comparing performance properties of various commercial explosives.

The Initiation of Covered Composition B by a Metal Jet

Abstract: The initiation and build-up to detonation of Composition B covered by steel barrier plates and impacted by a shaped-charge jet has been studied. Two different barrier thicknesses were used representing strong and weak shock initiating systems. The results showed that, in both cases, a shock (designated the precursor shock) that travelled ahead of the penetrating jet and entered the explosive was roduced when the jet impacted the steel surface. The strong precursor shock from the thin barrier system produced initiation close to the explosive surface while for the weak precursor shock from the thick barrier system there was a long run to detonation (40 mm, 11 μs). In the latter case, close to the onset of detonation, a retonation was observed moving back through the previously shocked explosive which was expanding radially. These observations are used to discuss and explain some of the apparent anomalies in previously reported work. The effect of the precursor shock on the classical jet penetration theory was estimated.

On the behaviour of nitrate esters in acid solution. III. Oxidation of ethanol by nitric acid in sulphuric acid

Abstract: The oxidation of ethanol as a model of the alcohols produced in the hydrolysis of nitrate esters, by nitric acid in aqueous sulphuric acid solutions has been studied with the aim to obtain information on the decomposition reaction of “spent acids”. The results show, in agreement with previous suggestions from this laboratory, that ethanol is firstly oxidized to acetaldehyde via a reaction initiated by nitric acid but carried on by NO2 radical. The latter is formed by the interaction of nitric and nitrous acids. The acetaldehyde is then oxidized by two independent paths leading one to acetic acid and the other to oxalic acid and eventually to CO2. The relevance of these findings on the understanding and on the control of „spent acids” is briefly discussed.

On the Break‐Up of Shaped Charge Jets

Abstract: It is shown from dimensional arguments that the semi-empirical jet break-up formula of Hirsch(1) is consistent with physical models characterized by ideal plasticity (yield stress σ0), the material initial density (ϱ0), strain rate (η0), and jet radius (r0). Similar arguments applied to a one-dimensional jet stretching model yields the existence of a maximum unstable perturbation wavelength, and fixes its value to within a numerical constant. Within the class of physical models considered the plastic velocity appearing in the Hirsch formula, the incremental velocity between successive fragments of a particulated jet, and the velocity (σ0/ϱ0)1/2 are all related, as originally conjectured by Hirsch.

Visible Spectra of Standard Navy Colored Flares

Abstract: : The visible spectra, color data and output powers from standard Navy red, green and yellow signal flares are presented. The spectra were taken under essentially identical conditions on actual in-service Navy devices. The dominant emissions accounting for the output power in the flares are from the molecular bands of the alkaline earth oxides, hydroxides and chlorides in the red and green flares and from atomic sodium in the yellow flare.

Factors Influencing the Pyrotechnic Reaction of Silicon and Red Lead

Abstract: The delay time of a column of pyrotechnic material when used in a delayed action electric detonator is defined as the time between the application of the initiating electrical impulse and the detonation of the explosive charge of the detonator. The effects of fuel/oxidant ratio and fuel surface area on the delay time have been measured for the silicon/red lead system. From the data obtained it has been possible to identify a possible reaction mechanism for this pyrotechnic composition.

Thermal Study on Picryl Azide (2‐azido‐1,3,5‐trinitrobenzene) decomposition using simultaneous thermogravimetry and differential scanning calorimetry

Abstract: Thermal decomposition of picryl azide has been studied under non-isothermal and isothermal conditions using a simultaneous TG-DSC technique. Picryl azide melts and then decomposes to give 4,6-dinitrobenzofurazan oxide which melts again and decomposes to gaseous products. Enthalpies (ΔH) of fusion and decomposition have been calculated. The order of reaction (n) is calculated and found to be one. Arrhenius parameters like specific rate constant (k), activation energy (Eact) and frequency factor (Z) have been calculated under both conditions using different methods. The values calculated from non-isothermal and isothermal techniques agree fairly well with each other. The observed lower activation energy when compared with phenylazide and 2-nitrophenyl azide is probably due to an enhanced ortho effect.

Precise assay of TATB by the determination of total amino and nitro functional groups

Abstract: Methods have been developed for the precise assay of the explosive l,3,5-triamino-2,4,6-trinitrobenzene (TATB) using procedures that quantitatively measure total nitro and/or total amino functional groups. The method for the determination of total nitro groups is based on the dissolution of TATB in DMSO-NaOH, electrolytic reduction of -NO2 to -NH2, and measurement by controlled-potential coulometry. The reduction is carried out at a mercury pool electrode at −0.60 V versus standard calomel electrode (SCE) in a supporting electrolyte 1 M in H3PO4 and 3 M in HClO4. Background corrections are low, and samples containing 0.1 mg to 2 mg of TATB per ml can be analyzed with a precision and accuracy of 0.25% to 0.5%. The method for determining total amino groups is based on the conversion of -NH2 to NH3 in a Kjeldahl-type apparatus. The sample does not require an acid digestion step. The - NH2 groups are readily converted to NH3 and distilled from a solution of NaOH and dimethylsulfoxide (DMSO). Individual samples of 120 mg-170 mg of TATB can be conveniently assayed for amino groups with an accuracy and precision of about 0.25%.

Mechanism of thermal decomposition of double base propellants

Abstract: Thermogravimetric studies were carried out with double-base propellants to find the rate-detg. stage and to understand the mechanism. The decompn. process can be divided into 3 stages as follows: diffusion of nitroglycerin [55-63-0] takes place at 120-160. Two processes occur at 170-205, namely the dissocn. of nitroglycerin and the cleavage of the C-O bond, the later being the rate-detg. step. The cleavage of the $C-O$ bond is followed by a considerable decompn. of nitrocellulose [9004-70-0].

Identification of Combustion Products from Colored Smokes containing organic dyes

Abstract: Devices producing different colored smokes have been widely used by military and civilians for signaling, screening, and display. Attention has not yet been placed on the analysis of the combustion products from these devices which may be hazardous. Combustion products from these colored smokes containing organic dyes produced at the normal function temperature (approximately 400°C–600°C) of the compositions have been studied in our laboratory. The five dyes contained in the smoke compositions studied are: benzanthrone, dibenzo(a,h)pyrene-7,14-dione, 1,4-di-p-toluidino-anthraquinone, 1-methylamino-anthraquinone, and α-xylene-azo-β-naphthol. A modified EPA-Method 5 sampling train containing Amberlite XAD-2 as the absorbant was used to sample the organic vapors and particulates in the effluent. analytical methods used to separate, purify, and identify the products include TLC, HPLC, GC, GC-MS, and NMR. Minimum destruction of the organic dyes is desired for a good smoke. Our preliminary investigations indicate that 90%–95% of the organic dye sublimes while the other 5%–10% is lost to combustion. The combustion products observed, to date, have been identified as polynuclear aromatic hydrocarbons (PAH's) and polynuclear organic materials (POM's) which are the result of thermal decomposition and thermal rearrangement of the parent dyes. At the temperature of functioning, no ring opening of the dyes has been observed.

Impact Sensitivity of γ-Irradiated HMX

Abstract: Impact of thin layers of HMX at room temperature and near liquid nitrogen temperature were performed. Polycrystalline powders of HMX irradiated with 7.5 megarad in evacuated tubes at liquid nitrogen temperature showed significant enhanced sensitivity. With 10-megarad irradiations of HMX in evacuated tubes at liquid nitrogen temperature frequent spontaneous explosions in HMX have occurred. ESR measurements on impacted HMX and RDX powders at room temperature and near liquid nitrogen temperature at energies of less than 1 kg · m have not produced detectable mechanically generated free radicals. A significant increase in sensitivity of vacuum irradiated HMX was observed but efforts to correlate this with the dominant frozen-in NO2 γ-radical concentration were unsuccessful. It is suggested that the NO2 radical is a chain terminating radical in explosive systems.

Décomposition thermique en phase gazeuse du nitrate d'isopropyle

Abstract: La decomposition thermique en phase gazeuse homogene du nitrate d'isopropyle a ete etudiee dans un tube a choc unique. On a utilise une methode comparative avec le peroxyde de di-t-butyle comme reference interne. Sur l'intervalle de temperature de 533 K a 635 K, l'expression de la vitesse pour cette decomposition du nitrate d'isopropyle obeit a la relation:

On the possibility of Detecting Case/Liner and Liner/Propellant Debonds in a Rocket Motor by means of the ultrasonic multiple reflection pulse echo technique

Abstract: In order to examine whether and to what extent the ultrasonic multiple reflection technique can be used for detecting case/liner and liner/propellant debonds, measurements were performed on samples sawn from a particular case-bonded rocket motor consisting of a layer of 2.4 mm steel, a layer of 1,3 mm liner material (a polymer) and a thick layer of composite (AP/PU) propellant respectively. It was found that case/liner debonds could be traced reasonably well; liner/propellant debonds, however, could not be evidenced owing to strong quenching of the ultrasound in the liner. Investigations of the texture of the liner material with the aid of a scanning electron microscope proved the strong quenching in the liner to be mainly due to the presence of many voids with diameters of some 50 μm–200 μm which strongly disperse the sound beam.

Thermal Decomposition of Guanidinium Perchlorate

Abstract: Thermal decomposition of guanidinium perchlorate has been studied by thermogravimetry, differential thermal analysis, mass spectrometry and X-ray diffractometry. The title compound undergoes crystallographic phase transformation at 180°C before melting at 255°C. It decomposes exothermally into gaseous products in the temperature range 275°C–325°C. The mass spectral results suggest that the compound undergoes thermal decomposition into neutral particles which are then vapourized, ionized and oxidized. The fragment cyanamide is found to undergo trimerization to give melamine.

A hexahydro‐1,3,5‐trinitro‐l,3,5‐triazine (RDX): ϵ‐caprolactone adduct

Abstract: A new unstable equimolar adduct of hexahydro-1,3,5-trinitro-1,3,5-triazine was formed with 6-hexanolactone (ϵ-caprolactone). Some properties of the adduct are presented. Eine neue Additionsverbindung von Hexahydro-1,3,5-trinitro-1,3,5-triazin (RDX) mit ϵ-Caprolacton Eine neue, nichtstabile, aquimolare Additionsverbindung von RDX wurde erhalten mit 6-Hexanolacton (ϵ-Caprolacton). Einige Eigenschaften der Additionsverbindung werden vorgestellt. Un nouveau compose par addition de l'hexogene et de l'ϵ-caprolactone On a trouve un nouveau compose equimolaire, instable resultant d'une reaction d'addition entre l'hexogene et la 6-hexanolactone (ϵ-caprolactone). On presente quelques proprietes de ce compose par addition.

Contribution à l'étude de propriétés des molécules d'explosif dans l'état active. II. Volumes molaires des derivés nitrés aromatiques

Abstract: Les increments de volumes moleculaires affecte a chaque atome ou groupement d'atomes ont ete determines sur dix explosifs aromatiques nitres, tant a l'etat cristallin qu'a l'etat active, au sens de la theorie cinetique de la detonation. Comme dans le cas des esters nitriques, on constate que seuls les groupements explosophores sont comprimes, ainsi que le groupe phenol. Les autres atomes ou groupements ont des volumes voisins de ceux determines dans les cristaux d'apres les regles d'additivite etablies recemment dans les solides cristallins.

Theoretical prediction of the velocity‐diameter relation of bubble‐sensitized liquid explosives

Abstract: Etude sur un modele base sur une combustion initiee par des points chauds permettant de simuler la reaction chimique dans un explosif liquide aere

Testing of a New Concept for the Storage of Granular Propellant

Abstract: A new concept for the storage of granular propellants envisages storage buildings that consist of a number of storage rooms arranged side by side, and which avail of a common entrance room. In order to examine the possible spreading of fire from one storage room to another during the deflagration of a propellant charge in one of the rooms, a number of deflagrations have been conducted in a experimental building which consists of three adjacent storage rooms and one common entrance room. The building itself is equipped with a valve-type roof whose corrugated sections pivot on one side. The steel doors leading from the entrance room into the storage rooms are of the lifting-type and are fitted with a dual labyrinth seal and an interspace ventilation. The middle storage room was used for 13 deflagrations of propellant charges ranging from 500 kg to 4500 kg. Four types of propellants of differing brisance were employed for the task. The measurements of the effects caused by deflagration upon the two neighbouring rooms and the surroundings of the building itself entailed considerable technical efforts. In virtue of the extensive test results the new storage concept is assessed as being safe.

A Parametric Study of the Synthesis of 2,2′,4,4′,6,6′‐Hexanitrostilbene from trinitrotoluene and sodium hypochlorite

Abstract: The synthesis of 2,2′,4,4′,6,6′-hexanitrostilbene by the action of alkaline sodium hypochlorite on 2,4,6-trinitrotoluene has been studied. The effects of time, temperature, pH, solvent composition and mode of TNT addition on the yield of HNS are discussed. The reaction, usually referred to as the Shipp synthesis, is shown to be highly susceptible to variations in process conditions, particularly base and water concentrations. The conversion of 2,4,6-trinitrobenzyl chloride, an intermediate in the Shipp reaction, to HNS has also been examined.

Contribution à l'étude de la thermolyse des esters nitriques

Abstract: Par IR, RMN et CCM, etude des produits de thermolyse du dinitrate d'ethyleneglycol de la nitroglycerine et du trinitrate de butanetriol-1,2,4

Cook‐off studies of propellants and explosives

Abstract: Etude theorique et experimentale du probleme du cook off; la temperature critique pour l'explosion thermique est analysee comme une fonction de la masse initiale du propergol; bon accord entre la theorie et les experiences

Application of the Robbins‐Monro method to the sensitivity testing of explosives. II. The experimental practice

Abstract: In this second part of a series of publications dealing with the application of the Robbins-Monro method to the sensitivity testing of explosives, the experimental aspects are treated. The results of an experimental program with a primer drop-test apparatus confirmed the efficiency which was concluded from the computer simulation study, also for extreme percentage points. Further a method is described to determine the reliability of the outcome after the execution of the Robbins-Monro process. It is shown that for an efficient application of the Robbins-Monro method the level distance which can be adjusted should be about 1/2 to 1/3 of the standard deviation (of a normal distribution) dependent on the percentage point.