Showing papers on "Ammonium perchlorate published in 1987"

Temperature sensitivity of Burning Rate of Ammonium Perchlorate Propellants

Abstract: The temperature sensitivity of burning rate of ammonium perchlorate (AP) composite propellants was studied as a function of AP particle size and a burning rate catalyst. A simplified temperature sensitivity model was presented in order to discriminate the effect of the gas phase and solid phase reactions on the initial propellant temperature (T0). The temperature sensitivity was decreased by the addition of small sized AP particles and/or 2,2-bis(ethylferrocenyl)propane (BEFP). This is caused by the insensitive burning surface temperature to T0. Thus, the gas phase reaction rate becomes little dependent on T0, and the temperature sensitivity decreases.

Combustion wave structure of AP composite propellants

Abstract: The combustion mechanism of ammonium perchlorate (AP) composite propellants were studied. The oxidizer-rich propellants tested were made with excess concentrations of AP particles. The pressure deflagration limit of propellant decreases with increasing the concentration of binder. The combustion wave consists of two reaction regions I and II: the region I is the zone of AP monopropellant flame and the region II is the zone of diffusion flame. The heat flux feedback from the gas phase to the burning surface increases as pressure increases, and the heat flux is responsible for the burning rate characteristics.

Thermal decomposition of doped ammonium perchlorate

Abstract: Isothermal decomposition of orthorhombic ammonium perchlorate (AP) has been studied as a function of concentration of the dopants, SO42− and PO43−. In either case, the rate of decomposition passes through a maximum as the dopant concentration increases. Activation energy of the decomposition process remains unaltered by doping. The results are interpreted in terms of electron transfer mechanism.

Simulating aluminum powder aggregation in mixed condensed-system combustion

Abstract: The combustion of a metal-loaded mixture is accompanied by the aluminum powder aggregating at the combustion surface; the main factors influencing this are: the natures of the fuel and oxidant; the mixture composition (component concentrations and sizes); and the combustion conditions. The authors assume that particle ignition has the decisive effect on residence times and clumping at the surface, which is used in a new approach to simulating the aggregation, as it enables one to incorporate the main factors influencing it and to explain the mechanisms in the combustion of condensed systems based on ammonium perchlorate.

Nitramine Solid Rocket Propellants with Reduced Signature

Abstract: Solid rocket propellants containing nitramine are considerably superior to doublebase propellants, both as regards their performance and mechanical properties. The pressure exponent of non-modified nitramine propellants is n ≥ 0.9. The possibility of changing the burning rate or, respectively, the pressure exponent has, however, only been realisable to a restricted extent up till now in propellants with an increased nitramine content. In the following propellant system containing nitramine, the effects of ammonium perchlorate on burning behaviour are studied: ammonium perchlorate (AP) hexogen (RDX) nitroglycerin (NG), or trimethylolethane trinitrate (TMETN) polyurethane binder (PU) AP concentrations already as great as 10% produce considerable changes in the burning behaviour of the propellants described above. It is possible to reduce the pressure exponent by the addition of ammonium perchlorate from n ≥ 0.9 to n ≤ 0.65. The burning rates may also be influenced with AP concentrations ≤ 20% and by varying the AP particle size by the factor of 2. All the propellants prepared were easily castable and showed exceptionally good viscoelastic properties (strain at break eR > 200%) in the temperature range between −40 °C to + 50 °C. The thermal chemical stability is not influenced negatively in any way by the combination of nitric acid esters and ammonium perchlorate.

Ballistic Modification of Composite Modified Double‐Base Propellants containing ammonium perchlorate

Abstract: The effect of certain lead and copper salts of organic acids and metallic oxides was studied on the burning rates and heat of explosion of CMDB propellants containing AP. Among lead and copper salts, basic lead salicylate gave increased burning rates, whereas lead methylene disalicylate and basic copper salicylate did not produce catalytic effect. In the case of metallic oxides, ferric oxide and cobalt oxide gave better catalytic activity than copper and chromium oxides. On crosslinking of nitrocellulose with an isocyanate, catalytic activity of ballistic modifiers was reduced. Burning rates obtained in a rocket motor (2-kg propellant) were higher by about 15%-20% than by strand burner (Crawford Bomb) method.

Method of generating crosslinking sites on the surface of ammonium perchlorate in solid interceptor propellants

Abstract: A method of generating reactive crosslinking sites on the surface of the onium perchlorate particles contained in a Catocene-catalyzed, high-burning rate solid propellant composition by a processing agent which also results in a major improvement in the processibility thereof. The fluid state of the propellant is retained during mixing as a result of interaction between the processing agent prepared prior to incorporating it or when the processing agent is prepared in situ during the propellant mix cycle. There are two alternates available toward improving the processibility of Catocene-catalyzed, high-burning rate propellants. These are: a. The synthesis of a condensation product (processing agent) by the interaction at room temperature of 1,3,5,7,9-pentaazanonane, acrylonitrile, oxiranylmethanol and octadecyl isocyanate in predetermined ratios; or b. Incrementally adding the octadecyl isocyanate to the propellant mix which incorporates the glycidol reaction product of cyanoethyl-substituted tetraethylenepentamine (Tepanol). A major improvement in processing can be effected as a result of the additions of octadecyl isocyanate in 1,2, or 3 increments to the Tepanol-containing mix.

Electrical conductivity of the burning surface of ammonium perchlorate

Abstract: The authors perform experimental measurements of the electrical conductivity of the surface of ammonium perchlorate during its combustion in order to gain insight into its combustion kinetics. Samples with additions of 5% copper salicylate and sodium salicylate were also investigated. Both additives were found to substantially increase the combustion rate. Electrical conductivity was found to depend heavily on temperature and pressure. Ionized combustion products are also analyzed. A full description of the experimental method and instrumentation is given.

Estimating heat production in the detonation of poured-density ammonium perchlorate

Abstract: The authors use an electromagnetic method to measure the mass-velocity profile in the detonation of a tamped charge of ammonium perchlorate (APC) in a strong shell. The profile for the mass velocity in the detonation wave was recorded by a two-arm electro-magnetic sensor. Calculations on the two-phase medium together with the mass-velocity profile are shown. High porosity at the front is found; much of the material burns at the front, during the first 0.5 ..mu..sec, which agrees with previous data. It is shown that the porosity in shock compression by a wave of amplitude 10 GPa would be not less than 0.2-0.45, which conflicts with the traditional mass velocity for complete pore collapse in strong shock waves.

Propellant Aging Research

Abstract: : Chemical aging of solid rocket propellants and ingredients was studied. The thermal decomposition rate coefficients of cyclotrimethylene trinitramine, butanetriol trinitrate, and ammonium perchlorate were measured from about 310 to 375 K using a NOx chemiluminescence analyzer. The decomposition of butanetriol trinitrate was shown to undergo a mechanism change at 333 K. Six cured mixtures of hydroxy terminated polybutadiene binder, ammonium perchlorate, aluminum, and stabilizer were prepared, exposed to four reactive gases for 54 hours at 344 K, and analyzed for weight change, sol/gel content, and molecular weight of sol. These techniques were not sensitive enough to reliably analyze early changes due to chemical aging. Polymer chemiluminescence resulting from chemical degradation of this series of propellant mixtures by reactive gases was also studied from 300 to 350 K. This work showed that the stabilizer methylnitroanilline significantly reduces chemical reactions occurring upon exposure to air but not upon exposure to air but not upon exposure to NO2/air. The results of this program demonstrate the capabilities of the real-time NOx offgas analysis technique and the polymer chemiluminescence technique. Keywords: Propellant aging; Energetic materials; Kinetics.