Showing papers in "Propellants, Explosives, Pyrotechnics in 1976"
TL;DR: In this paper, a general model for the shock initiation of explosive reaction in chemical explosives is proposed based on the concepts of: (1) the kinetics of decomposition in which ions and free radicals produced by the shock wave shear forces initiate chain reactions that contribute to and accelerate the decomposition produced by thermally activated molecules; (2) the formation of statistically random reaction sites whose number in a specific explosive is a direct function of the shock pressure as the shock transits the explosive; and (3) a critical energy-fluence requirement for initiation.
Abstract: A general model for the shock initiation of explosive reaction in chemical explosives is proposed. The model is based on the concepts of: (1) the kinetics of decomposition in which ions and free radicals produced by the shock wave shear forces initiate chain reactions that contribute to and accelerate the decomposition produced by the thermally activated molecules; (2) the formation of statistically random reaction sites whose number in a specific explosive is a direct function of the shock pressure as the shock transits the explosive; and (3) a critical- energy-fluence requirement for initiation. This model appears to apply to explosive reaction in gases, liquids, and solids.
61 citations
TL;DR: In this paper, a thin-layer chromatographic method was developed in connection with the determination of the safe lifetimes of gun propellants, which enabled the numerous stabilizer reaction products of diphenylamine and ethylcentralite, which were formed on storage, to be qualitatively analysed.
Abstract: A thin-layer chromatographic method was developed in connection with the determination of the safe lifetimes of gun propellants. This method enabled the numerous stabilizer reaction products of diphenylamine and ethylcentralite, which were formed on storage, to be qualitatively analysed.
Since a correlation could be established between the temperature and the decomposition or formation of certain of these reaction products, it became possible to estimate the time of onset of autocatalytic decomposition of powders and solid propellants from an analysis of the material at much earlier times.
27 citations
TL;DR: In this article, a correlation between the temperature and the storage period has been established for the results obtained at the respective temperatures, and it has been shown that continuing aging of the propellant gives rise to stabilizer reaction products which are quite characteristic of the respective aging condition.
Abstract: While stored at various temperatures between 65°C and 90°C, several double base propellants with the Same composition differing only in the stabilizer, were aged artificially to the onset of autocatalytic decomposition. A correlation between the temperature and the storage period has been established for the results obtained at the respective temperatures.
Moreover, studies were carried out on the chromatographic analysis of stabilizer reaction products of the type occurring in particular in propellants with diphenylamine, 2-nitrodiphenylamine, acardite I, acardite 11, and ethylcentralite as a result of storage at elevated temperatures due to reactions with the decomposition products of nitric acid esters.
It has been shown that continuing aging of the propellant gives rise to stabilizer reaction products which are quite characteristic of the respective aging condition. These reaction products may be used as a criterion for different stages of aging within the shelflife of solid propellants.
22 citations
TL;DR: In this article, the second and third virial coefficients for and mixtures of gases were calculated using potential functions, and a FORTRAN program was set up for these calculations.
Abstract: In calculating interior ballistics quantities the virial equation state is applied as an equation of state for real gases. A method shown of calculating the second and third virial coefficients for and mixtures of gases by using potential functions. A FORTRAN program has been set up for these calculations.
13 citations
12 citations
TL;DR: In this paper, the empirical formula for the distribution of fragments from rotationally-symmetric, cylindrical warheads can be extended to the case high explosive shells, and the parameters arising from this can be determined by fitting the measured results to the theoretical values.
Abstract: The empirical formula for the distribution of fragments from rotationally-symmetric, cylindrical warheads can be extended to the case high explosive shells. The parameters arising from this can be determined by fitting the measured results to the theoretical values. In this work possible methods of performing such a fitting procedure are discussed.
9 citations
TL;DR: In this article, the authors used micro-analysis, colorimetry and spectrophoto metry to establish the compositions (metal : ligand ratio) of these picramates as 1 : 2 and 1 : 4 for titanium and zirconium, respectively.
Abstract: Picramates of titanium, zirconium and thorium are prepared by treating the aqueous sulphate, chloride and nitrate solutions with sodium picramate. Micro-analysis, colorimetry and spectrophoto- metry are used to establish the compositions (metal : ligand ratio) of these picramates as 1 : 2 (for titanium and zirconium) and 1 : 4 (for thorium). IR studies indicate H2N → Me coordination (where Me denotes the metal). A number of explosive properties of these picramates point to the fact that the zirconium picramate is thermally more stable than the picramates of titanium and thorium.
6 citations
TL;DR: In this article, the relationship between quantity of explosive and cladding parameters such as angle of collision and plate velocity vp is determined, and the interface between lead-copper and lead-steel claddings is wave-like.
Abstract: Lead has for a long time not been employed in explosive cladding because its velocity of sound (c = 1250 m/s) is very low compared to the detonation velocities of conventional explosives (vD ≈ 3000 m/s). I t is shown that by using a carbonite explosive, which has a detonation velocity of less than 1500 m/s, useful explosive cladding can be achieved. The relationship between quantity of explosive and cladding parameters such as angle of collision and plate velocity vp is determined. The interface between lead-copper and lead-steel claddings is wave-like. The wavelength depends on the angle of collision and is larger for lead-copper claddings than for those between lead and steel.
4 citations
TL;DR: In this paper, twelve nitro- or chloroaromatic amines were oxidized to the nitro analogues by a simplified procedure, and the results showed that the method was suitable for a wide range of amines.
Abstract: Twelve nitro- or chloroaromatic amines were oxidized to the nitro analogues by a simplified procedure. Limitations of the method are indicated.
4 citations
TL;DR: For a series of double base rocket propellants and for poly-methylmethacrylate (PMMA) the longitudinal and transverse sound wave velocities are measured at a frequency of 0.351 MHz in t h e temperature range of −40°C to +60°C.
Abstract: For a series of double base rocket propellants and for poly-methylmethacrylate (PMMA) the longitudinal and transverse sound wave velocities are measured at a frequency of 0.351 MHz in t h e temperature range of −40°C to +60°C. The relations between these acoustic properties and mechanical properties are given and the principal independent elastic constants are calculated. With increasing temperature these constants of the propellants decrease gradually, which points to a softening of the material. This is important for the functioning of the propellant grains in the rocket motors.
4 citations
TL;DR: In this article, the irreversible conversion of mechanical to electrical energy in ferroelectric ceramics of the Pb(Zr1-xTix) O3 type with a considerable proportion of zirconium is studied.
Abstract: In order to find materials with increased specific electrical energy, especially for impact fuzes, the irreversible conversion of mechanical to electrical energy in ferroelectric ceramics of the Pb(Zr1-xTix) O3 type with a considerable proportion of zirconium is studied. The depolarization of the ceramics is measured for shock compressions between 0 and 30 kbar. The maximum electrical energy, obtained at about 18 kbar, is of the order of 1.8 J/cm3 with Pb(Zr0.965Ti0.035)03 + 1% Nb2O5 and of the order of 0.8 J/cm3 with a Pb(Zr0.54Ti0.46)03 + 1% Nb205. As an example for application, the initiation of a 3.5 ω bridge wire PETN detonator is described.
TL;DR: A computer program in FORTRAN I1 was developed and used for the evaluation of two process examples from the analytic field of explosives, i.e. determination of nitroglycerin and nitroglycol by means of gas chromatography.
Abstract: The principles of the statistical valuation for the comparison of analytical procedures by evaluating model analyses are described. A computer program in FORTRAN I1 was developed and used for the evaluation of two process examples from the analytic field of explosives, i.e. determination of nitroglycerin and nitroglycol by means of gas chromatography.
TL;DR: In this paper, a new type of manometric bomb of 0.1 1 volume has been designed to determine burning velocities of solid propellants at high pressures, and the bomb has been applied to measure pressures p in a range up to 7000 bar as a function of loading density A for a double base propellant.
Abstract: To determine burning velocities of solid propellants at high pressures, a new type of manometric bomb of 0.1 1 volume has been designed. Tightening is provided by a cartridge section from a 30 mm HS 831 steel case. 3 0 to 50 ms after the maximum, the pressure is automatically released by erosion of a 1 mm nozzle, this time lag being given by the electric igniter placed before the nozzle and by blocking it for a short time.
The bomb has been applied to measure pressures p in a range up to 7000 bar as a function of loading density A for a double base propellant. The curve p(A) shows a change of slope at about 5000 bar for which explanation is still lacking.
TL;DR: The air blast effect produced by high explosives with additives of various types and quantities was studied in this paper, where air shock intensities and pressure profiles were recorded at certain distances from an unconfined charge.
Abstract: The air blast effect produced by high explosives with additives of various types and quantities was studied. To this end, air shock intensities and pressure profiles were recorded at certain distances from an unconfined charge. Among those additives which by their reaction with the gaseous products of the detonated explosive theoretically should increase the energy potential, aluminum and zirconium exhibit a positive effect while other substances such as boron react too slowly for strengthening the blast effect. An addition of aluminum (32 weight%) causes the shock wave pressure to increase by about 15% and the momentum by 30% as compared with the pure explosive.
TL;DR: In this paper, the effects of various processing and compositional variables the cure rate and mechanical properties of epoxide-cured CTPB gumstocks have been evaluated, and the effects due to plasticisers and ammonium perchlorate filler also are reported.
Abstract: The effects of various processing and compositional variables the cure rate and mechanical properties of epoxide-cured CTPB gumstocks have been evaluated.
Viscosity changes during the initial stages of cure and tensile properties of fully cured gumstocks are sensitive to the nature and functionality of the epoxide curative even though comparisons are made at epoxy/carboxyl equivalence ratios giving the same density of crosslinks. Batch-to-batch variations in prepolymer structure, functionality and impurities also are important. In particular, glutaric acid impurity inhibits the cure, the effect being very marked when the mixing procedure involves heating the prepolymer and catalyst together before the addition of epoxide.
Effects due to plasticisers and ammonium perchlorate filler also are reported. The mechanical behaviour of gumstocks and of corresponding filled systems (propellants) show little correlation.
TL;DR: The mechanism of the thermal decomposition of hydrazinium diperchlorate (HP-2) has been investigated in the temperature range $100-200^oC.
Abstract: The mechanism of the thermal decomposition of hydrazinium diperchlorate (HP-2) has been investigated in the temperature range $100-200^oC$. The decomposition can be represented by the chemical equations:
$Below 140^oC N_2H_6(ClO_4)_2 \rightarrow N_2H_5ClO_4 +HClO_4$
$Above 140^oC 2N_2H_6(ClO_4)_2 \rightarrow 8NH_4ClO_4 +42H_2O + 26HClO_4 + 14N_2O + 7Cl_2 + 6N_2 + H_2$
The solid state decomposition up to $180^oC$ ensues with an activation energy of 23 kcal/mole whereas above $180^oC$ in the molten state the activation energy is 35 kcal/mole.
TL;DR: In this paper, the effect of acoustic field on the thermal conductivity of composite propellants based on poly-butadiene and polyurethane binders was investigated and it was shown that the thermal properties of composite materials increase when they are subjected to an acoustic field.
Abstract: A study is conducted to determine the effect of acoustic field on the thermal conductivity of composite propellants based on poly- butadiene and polyurethane binders. The thermal conductivity of the propellant is determined by a specially designed equipment. The thermal conductivity measurements are made in steady state conditions and in an acoustic field of constant amplitude at various frequencies ranging from 1 kHz to 6 kHz and at different temperatures ranging from 30°C to 50°C. The results indicate that the thermal conductivities of the composite propellants increase when they are subjected to an acoustic field. The data obtained are presented in the paper. Since the burning behaviour of solid propellants is influenced also by its thermal conductivity, the present work may be of direct relevance in improving upon some of the existing burning rate and combustion models.
TL;DR: In this article, the authors measured the steady state detonation velocities in small brass-confined pressings of PETN and found that the velocity varied linearly with the reciprocal of the charge diameter and directly with the compact density.
Abstract: Steady state detonation velocities have been measured in small brass-confined pressings of PETN. These velocities were found to vary linearly with the reciprocal of the charge diameter and directly with the compact density. For a pressing density of 950 kg/m3 the velocity at infinite diameter was calculated to be 5.27 km/s (50.02 kmk) and the Eyring-type „reaction-zone length” 0.54 mm (±0.02 mm).
TL;DR: In this article, the equations for equilibrium in a chemically reacting gas composition without solid phase are derived by virtue of the virial equation as an equation of state, and the internal energy and the enthalpy of the powder gases are given for the computation of the explosion temperature and the adiabatic flame temperature.
Abstract: The interaction of powder gas molecules in the interior ballistic pressure and temperature range does not allow the application of the Nobel-Abel equation of state. An equation of state which correlates the thermodynamic variables pressure, specific volume, and temperature, and which meets to a high extent the physical facts, is the virial equation. Using an additive combined theorem for the virial coefficients, the equations for equilibrium in a chemically reacting gas composition without solid phase are derived by virtue of the virial equation as an equation of state. The internal energy and the enthalpy of the powder gases are given for the computation of the explosion temperature and the adiabatic flame temperature. For a numerical solution of this non-linear system of equations, a combination of the gradient process and the Newton-Raphson process (Such-Weg-Verfahren) is applied. Furthermore, the numerical results for different propellant powders are stated and discussed.
TL;DR: In this article, a thermodynamic model of the internal ballistics was used to optimize the properties of the propellant in a charge of a conventional design, and an example of the application of the theoretical results is discussed.
Abstract: An improvement in internal ballistic performance is understood to mean an increase in muzzle velocity for the same weight of projectile and the same peak pressure. Using a thermodynamic model of the internal ballistics a possible method of achieving a significant improvement in performance is demonstrated based on optimizing the properties of the propellant in a charge of conventional design. An example of the application of the theoretical results is discussed.
TL;DR: In this paper, the small fall-hammer of BAM (Bundesanstalt fur Materialprufung) has been characterized using the theory of the forces between two colliding bodies.
Abstract: In order to characterize the small fall-hammer of BAM (Bundesanstalt fur Materialprufung) its mechanical properties were determined. Using the theory of the forces between two colliding bodies expressions were derived to describe the tester which were validated by the experimental measurements. I t was found that forces of up to 21 kN were transmitted to the anvil (for 1 kg weight dropping through 0,s m) and that the impact times ranged from about 150 f i s for the small weights to about 500 f i s for the large weights. It was also found that in addition to the expected kinetic energy dependence of the forces on the anvil there was also a dependence on the actual weight used.