Begell House Inc.
International Journal of Energetic Materials and Chemical Propulsion
IJEMCP
2150-766X
11
5
2012
THERMOELECTRIC PULSE POWER GENERATION USING SELF-SUSTAINING GASLESS NANOREACTANT SYSTEMS
389-399
10.1615/IntJEnergeticMaterialsChemProp.2013002399
Jan
Puszynski
SDSM&T
Rajesh V.
Shende
Chemical and Biological Engineering Department, South Dakota School of Mines and Technology, Rapid City, South Dakota 57701
Magdy
Bichay
Naval Surface Warfare Center, Indian Head, Maryland 20640
nanothermites
ignition
energetic nanocomposites
Thermoelectric (TE) modules that convert heat into electricity and vice versa (Seebeck−Peltier effect) have great potential in the field of short-term power generation. Commercially available TE modules are manufactured with a series of p- and n-doped semiconductor materials sandwiched between two ceramic face sheets. A commonly used ceramic material in these devices is Al2O3, which has a relatively low thermal conductivity (28 W/m·K). If it is replaced with a material with higher thermal conductivity, such as AlN (180 W/m·K), significantly faster electrical pulses may be generated. In this paper, pulse voltage generation was investigated using a self-sustaining nanothermite reactive system containing Fe2O3/Al coated on Al2O3 or AlN face plates of a TE module. Al2O3 substrates of two TE modules were coated directly with Fe2O3/Al and were placed on top of each other with Ni−Al foil sandwiched in between the two coated surfaces. Upon ignition of this hybrid reactive system, a pulse of 6 V with the rise time of about 200 ms was generated. Experiments have shown that the replacement of Al2O3 with AlN reduces the rise time. The effect of a gasless reacting system−such as reactive powder, foil, and combinations thereof−on dynamic voltage generation in TE modules is presented.
FORMATION OF CONSOLIDATED NANOTHERMITE MATERIALS USING SUPPORT SUBSTRATES AND/OR BINDER MATERIALS
401-412
10.1615/IntJEnergeticMaterialsChemProp.2013002401
Jan
Puszynski
SDSM&T
Chris J.
Bulian
Chemical and Biological Engineering Department, South Dakota School of Mines and Technology, Rapid City, South Dakota 57701
Jacek J.
Swiatkiewicz
Chemical and Biological Engineering Department, South Dakota School of Mines and Technology, Rapid City, South Dakota 57701
Deepak
Kapoor
Armament Research, Development, and Engineering Center, Picatinny Arsenal, NJ 07806 USA
nanothermites
ignition
energetic nanocomposites
Consolidated nanothermite felts with reduced sensitivity to electrostatic discharge for safer handling were produced without a significant reduction of the nanothermite reactivity. A polyester felt material with a thickness of 1.65 mm was easily infiltrated with a nanothermite slurry and the dried felt material prevented small particles from breaking off during handling. Combustion of 100 mg of the dried felt nanothermite in a closed-volume pressure cell generated higher pressure than those generated by nanothermite granules produced using a similar water-based processing method. The nanothermite felts also effectively absorbed nitrocellulose as a gasifying agent without a significant decrease in reaction rate. High-density reactive composites, based on tantalum metal fuel with a specific gravity of 16.6 and nanoscale Bi2O3 oxidizer, were formed with densities in excess of 5.0 g/cm3. THV 220A, a fluorocarbon polymer with oxidizing properties, was used as an effective binder in the composite. These materials were combined in acetone with tetrafluoroethylene, hexafluoropropylene, and vinylidene (THV), and after drying were pressed into pellets. Combustion of an 800-mg pellet lasted 5 s and was accompanied by the formation and ejection of hot particles from the surface of the pellet. Differential scanning calorimetry analysis determined that the ignition of the high-density composite occurs below 620 K, which is lower than common in nanothermite systems.
DEFORMATION-INDUCED HOT-SPOT CONSEQUENCES OF AP AND RDX CRYSTAL HARDNESS MEASUREMENTS
413-425
10.1615/IntJEnergeticMaterialsChemProp.2013005348
Ronald W.
Armstrong
Center for Energetic Concepts Development, University of Maryland, College Park, MD, USA
Scott G.
Bardenhagen
Wasatch Molecular, Inc., Salt Lake City, Utah 84103, USA
W. L.
Elban
Loyola University Maryland, Baltimore, Maryland 21210, USA
AP
RDX
hardness
dislocation pileup avalanches
hot spots
crystal size dependence
composite formulations
particle contiguity
Elastic, plastic, and cracking indentation measurements obtained in nano- to micro- to macroindentation hardness tests of ammonium perchlorate (AP) and cyclotrimethylenetrinitramine (RDX) crystals are usefully described on a hardness stress−strain basis and are assessed in terms of the dislocation pileup avalanche mechanism for hot-spot generation associated with sudden crack formation. The model considerations lead to interpretation of a particle size influence on the drop-weight height for 50% probability of onset of reaction, now extended to include recently reported results for ε-hexanitrohexaazaisowurtzitane (ε-HNIW) crystals. These considerations are extended to deformation of individual or interacting groups of crystals when incorporated within a composite formulation and in relation to the potential brittleness of the binder material if undergoing transition to a glassy structure.
COMBUSTION MECHANISM OF ENERGETIC BINDERS WITH NITRAMINES
427-449
10.1615/IntJEnergeticMaterialsChemProp.2013005557
Valery
Sinditskii
Mendeleev University of Chemical Technology
Viacheslav Yu.
Egorshev
Department of Chemical Engineering, Mendeleev University of Chemical Technology, 9 Miusskaya Sq., 125047, Moscow, Russia
Valery V.
Serushkin
Department of Chemical Engineering, Mendeleev University of Chemical Technology, Moscow, 125047, Russia
Sergey A.
Filatov
Department of Chemical Engineering, Mendeleev University of Chemical Technology, Moscow, 125047, Russia
Anton N.
Chernyi
Department of Chemical Engineering, Mendeleev University of Chemical Technology, 9 Miusskaya Sq., 125047, Moscow, Russia
energetic hinder
nitro esters
nitramines
leading reaction of combustion
combustion mechanism
burning rate
The paper describes the results of a combustion study of the binary compositions of nitramines [tetranitrotetraazacyclooctane (HMX), trinitrotriazacyclohexane (RDX), tetranitrotetraazabicyclooctane (Bi-HMX), hexanitrohexaazaisowurtzitane (CL-20)] with two nitro ester binders, in which combustion complies with two different mechanisms; i.e., a gas-phase mechanism for volatile ener¬getic materials and a condensed-phase mechanism. It is shown that in compositions in which the binder is characterized by gas-phase combustion, HMX in concentrations up to 50% acts as an inert additive. Depending on the size and concentration of the HMX particles, three types of combustion of the mixtures can be identified; i.e., combustion along the binder interlayer, combustion as a single system, and combustion with a coolant. At higher nitramine concentrations, combustion control passes to nitramine and the burning-rate controlling reaction occurs in the liquid phase of nitramine. Only two combustion models are realized in the case of the binary compositions of a volatile binder with nitramines, which are less stable and burn faster than HMX (Bi-HMX and CL-20); i.e., the mixtures can burn either by a model with fast-burning additives or as a single unit. For the binary compositions of RDX and HMX with the binder, in which combustion obeys the condensed-phase mechanism, the model with fast-burning additives can be realized for a narrow set of conditions. The compositions mostly burn only as a single unit, and the addition of nitramine increases the burning rate of nitro ester by transferring heat from the overlying zone to the condensed phase.
COMBUSTION OF PTFE-BORON COMPOSITIONS FOR PROPULSION APPLICATIONS
451-471
10.1615/IntJEnergeticMaterialsChemProp.2013005791
Gregory
Young
Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute
and State University, Blacksburg, VA, USA
Chad A.
Stoltz
Naval Surface Warfare Center - Indian Head Division, Research and Development Department, Indian Head, MD
Brian P.
Mason
Naval Surface Warfare Center - Indian Head Division, Research and Development Department, Indian Head, MD
Vasant S.
Joshi
Naval Surface Warfare Center - Indian Head Division, Research and Development Department, Indian Head, MD
Reed H.
Johansson
Department of Aerospace Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Terrence L.
Connell, Jr.
Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Grant
Risha
Penn State
Richard A.
Yetter
Department of Mechanical Engineering, Pennsylvania State University,
University Park, Pennsylvania, 16802, USA
hybrid rocket
solid fuel
boron
PTFE
teflon
An experimental study was conducted to evaluate the potential of solid fuels based on PTFE and boron mixtures for hybrid rocket motor applications. Specifically, a processing technique based on sintering was studied to determine the viability of these fuels. Sintering of the fuels provided reasonable mechanical properties to allow for exploration of these fuels without the addition of performance-robbing ingredients. Linear regression rates of sintered and unsintered fuels were collected in a diffusion flame setting with gaseous oxygen as the oxidizing component demonstrating that the sintering process had no effect. This family of fuels has shown that they will not combust at atmospheric pressure unless pure oxygen is present. However, sintered fuels with boron loadings greater than or equal to 25% by weight do self-propagate at atmospheric pressure once ignited in the presence of oxygen, whereas unsintered fuels do not self-propagate unless they have boron loadings greater than or equal to 30% by weight. At pressures up to 12 MPa, fuels containing 10% by weight boron would not self-propagate in a nitrogen atmosphere, whereas fuels containing 20% boron would self-propagate at pressures greater than about 5.7 MPa. Preliminary lab-scale rocket motor firings demonstrate the viability of a hybrid rocket based on PTFE and boron mixtures. In addition, they demonstrate that the regression rates of these fuels show dependencies on pressure and possibly oxidizer flow rate as well. Thermochemical analysis suggests that these fuels offer a significant performance benefit in terms of density impulse, while also presenting a significant technological challenge due to excessively high flame temperatures for some mixtures.
TRANSIENT BURNING BEHAVIOR OF PHASE-STABILIZED AMMONIUM NITRATE BASED AIRBAG PROPELLANT
473-486
10.1615/IntJEnergeticMaterialsChemProp.2013005394
Jonathan T.
Essel
Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802
J. Eric
Boyer
Department of Mechanical Engineering, Pennsylvania State University,
University Park, Pennsylvania, 16802, USA
Kenneth K.
Kuo
Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802, USA
Baoqi
Zhang
Department of Mechanical and Nuclear Engineering The Pennsylvania State University, University Park, PA 16802 USA
dynamic burning
rapid pressure excursions
airbag inflators
ammonium nitrate
real-time x-ray radiography
Understanding the burning rate of an automotive airbag propellant is extremely important. Airbag propellants need to produce gas on the order of milliseconds. The speed with which the airbag inflator needs to work ensures that the propellant experiences a large pressure transient during combustion. Therefore, one factor that needs to be considered with airbag propellant combustion is how the propellant burns under a rapidly changing chamber pressure. This paper presents the results from a study on the dynamic burning behavior of a phase-stabilized ammonium nitrate (PSAN) propellant during rapid pressure changes. First, the steady-state burning behavior of the propellant was investigated with an optical strand burner and it was found that the burn rate could befit to Saint-Robert's law with the expression being rb,ss = 1.393P0.873 for pressures up to 28 MPa and rb,ss = 3.779P0.570 for higher pressures. Second, the dynamic burning behavior of the propellant was measured directly in an "O-frame" chamber that used real-time x-ray radiography (RTR) to measure the instantaneous regression behavior of the propellant. For high-pressurization rate tests (~2000 MPa/s), the dynamic burning rate was found to be almost twice the steady-state value. Finally, the dynamic burning data taken from pressure and RTR system measurements was fit to a correlation relating the dynamic burning rate to the instantaneous chamber pressure and pressurization rate. Almost all of the experimentally determined dynamic burn rates were found to be within ±15% of the correlated expression.