Figure 7. An effect on the ignition delay is also affected by the inclusion of amorphous boron  see Figure 7. Chaudhri et al. The actual Mg particle distribution ranged from submicron size to a few microns. From these experiments, it is obvious that laser ignition of MTV is based on absorption of radiation by Mg particles and subsequent heating.
The adjacent polymer is decomposed, which is seen on non-ignited samples as darkening of it. This kind of darkening does not occur with pure PTFE samples . However, radiative ignition will not occur below a certain nucleus size believed References Ignition delay, td s 10 1 0,1 Temperature, T K Figure 7. Fetherolf, B. Kuo and J. France, June 8—12, p. June 24—28, p. Blachnik, H. Al-Ramadhan, F. Chaudhri, M. McLain, H. D: Appl. Ramaswamy, A. Armstrong, R. Haq, I. In accordance with their results, fuel-rich pyrolants display low-pressure exponents, whereas fuel-lean pyrolants exhibit pronounced sensitivity to pressure changes.
The ambient pressure combustion behaviour of pyrolants made from Figure 8. The pressure sensitivity for a series of MTV pyrolants is shown in Figures 8. Generally, the burn rate increases with increasing pressure.
Metal-Fluorocarbon Based Energetic Materials
As the PTFE content decreases, the pressure sensitivity also decreases. Although fuel-rich formulations have a rather linear slope, PTFE-rich formulations display an exponential increase of burn rate with rising pressure, indicating a different combustion mechanism Tables 8. Table 8. At higher pressures, these effects are compensated by better heat transfer as can be seen by the convergent lines in Figure 8.
Ladouceur explained the lower burn rate with preferred CF4 formation in oxygeneous atmosphere. CF4 reacts slower with Mg than that with CF2 and, thus, is held responsible for the observed lower burn rate . The Vieille parameter for Figure 8. Parameter a n Air Nitrogen 0. It shows the exponential slope typical for PTFE-rich formulations . The variation of combustion rate with stoichiometry at 6 MPa is shown in Figure 8.
E.-C. Koch on Energetic Metal-Fluorocarbon Materials and Munitions Safety
Its sigmoidal shape of the pressure curve is indicative of two mechanistic transitions as proposed in . A similar yet different burn rate model has been applied by Kuwahara et al. The schematic combustion shown in Figure 6. Unlike Kubota , Kuwahara  took into account energy-releasing reactions in the condensed phase as well.
However, his analytical model requires only burn times and does not need to solve the heat and mass balance equations for this case. In addition, the release of hydrogen facilitates combustion in oxygeneous environments. The measured combustion temperatures are given below in Table 8. Thermochemical codes fail to converge for these fuel-rich stoichiometries as the reaction products are in the condensed phase exclusively. After cooling of the vessel, the remainder pressure was back at the initial value 0. It is concluded that condensed phase heat transfer is the sole mechanism by which the reaction propagation is controlled.
The burn rate increases with decreasing density and increasing metal content Figure 8. The rate of combustion increases with increasing metal content and is faster with small Ti particles. The burn rate at 0. The pressure dependence of three different binary pyrolants is shown in Figure 8. The results for both micrometric and nano-metric aluminium blended with nm PTFE particles are shown in Figure 8. The burn rate of the nano-pyrolant is approximately an order of magnitude greater than that of the micro-pyrolant. The combustion rate of pressed nano-AlTV as a function of stoichiometry at 1.
The pressure dependence as a function of stoichiometry of consolidated AlTV is shown in Figure 8. Generally, the pressure dependence varies with pressure for these stoichiometries. This has been explained with coincidence of the measurement conditions with the low-pressure transition range in the Ward—Son—Brewster combustion model. That is transition from the condensed phase-controlled reaction to gas-phase controlled regime Table 8.
Energetic Materials Combustion Lab
They also explored the pressure sensitivity of these pyrolants in the range between 0. Yarrington et al. Above the point, fast glowing of the pyrolant strand with eventual terminal sparkling or explosion is encountered.
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The combustion of a pressed stoichiometric mixture is shown in Figure 8. However, only a binary near-stoichiometric composition Reproduced with kind permission by Prof. At low densities, a fast consumption with a single large plume is observed, whereas at increasing density the burn rate slows down Figure 8.
Flame, 76, 57— Miyata, K. Jackson, D. Hall, A. Propulsion, 3, — Pyrotech, 22, — Kayaku Gakkaishi, 59 1 , 18— Speckart, E. Chen, D. Yang, V. Peretz, A. Valenta, F. Ward, M.
Theory Model. Frolov, Y. Kashparov, L. Burning velocity of two-component mixtures of magnesium with sodium nitrate. Shock, 30, — Klyachko, L. Shock, 7, — Biermann, U. US Patent 3,,, Germany. Smith, R. Chen, M. Laser Infrared, 35, — Takizuka, M. High Press. Wilker, S. Watson, K. Texas Tech University. Yarrington, C. Power, 26, — Farnell, P. Ksiazczak, A. Trzcinski, W. Hahma, A.