Showing papers on "Ammonium perchlorate published in 2007"

Nanoscale Additives Tailor Energetic Materials

Abstract: The effect of anatase, rutile, and amorphous TiO2 nanoparticles on the combustion of solid rocket propellant was investigated. Each additive increased the burning rate of propellant strands by 30%. Typical fast-burning propellants are unstable due to oversensitivity to pressure variations, but the anatase additive yielded propellants with high yet stable burning rates over a broad pressure range. Anatase nanoparticles also catalyzed the high-temperature decomposition of ammonium perchlorate, a key component of solid propellant.

Regression rates study of mixed hybrid propellants

Abstract: The low regression rates of classic hybrid rocket fuels lead to large internal ports that limit potential applications. This experimental study investigated the increase in regression rate that results from adding a solid oxidizer and a catalyst to a hybrid fuel grain. The configuration is named a "mixed hybrid" hybrid to signify solid oxidizer and catalyst in the grain. A design of experiments approach guided fuel formulation to systematically control levels of ammonium perehlorate from 25% to 30%, ferric oxide from 0 to 5%, and hydroxyl-terminated polybutadiene from 70% to 75%. The 1.5-in. diam. port, 12-in. long center perforated grains were burned with gaseous oxygen at pressure levels from 150 to 550 psig and port flux levels from 0.1 to 0.4 lbm/s-in. 2 . The results show that the mixed hybrid propellants burn as a function of both pressure and mass flux. A grain formulation having 27.5 % ammonium perchlorate and 2.5% ferric oxide provided the maximum burning rate augmentation (447%) among the formulations tested.

Nanosized components of energetic systems: Structure, thermal behavior, and combustion

Abstract: Ultrafine and nanosized powders of oxidizers and metals are considered as promising ingredients for the development of new highly effective solid rocket propellants. An ultrafine ammonium perchlorate (AP) powder and nanosized aluminum were produced by mechanical activation and investigated using electron and atomic force microscopy and X-ray powder and thermal analyses. It is shown that the activation energy of nanoaluminum oxidation is considerably lower than that for the micron-size powder, and the activation energy of the high-temperature decomposition for standard AP exceeds that for ultrafine AP. The exponent in the burning rate law decreases, and the burning rate increases by an order of magnitude if micron-sized aluminum is completely replaced by nanoaluminum in stoichiometric compositions containing ultrafine AP.

Computer model of aluminum agglomeration on burning surface of composite solid propellant

Abstract: The process of agglomeration of aluminum particles on the burning surface of an ammonium perchlorate-based composite propellant is modeled using a computer algorithm. A random pack of particulate ingredients of given size and mass specifications is cast on the computer to simulate the propellant microstructure as reported previously. The aluminum particles are tracked as they emerge at a regressing burning surface, accumulate into filigrees, and get ignited by the near-surface leading-edge oxidizer-binder diffusion flamelets attached to the exposed areas of certain ammonium perchlorate particles. An approximate heat transfer model is incorporated to estimate the ignition delays radially inward and outward from the leading-edge flamelets into the filigrees accumulated over ammonium perchlorate particles and surrounding binder-fine ammonium perchlorate matrix layers. The delay influences the number of parent aluminum particles constituting a filigree, and consequently the size of the agglomerate that the filigree rolls up into. The implementation of the algorithm is validated against experimental results available in the literature, which were specifically obtained to investigate the relationship between the decrease in the agglomerate size and attachment of leading-edge flamelets over the fine ammonium perchlorate particles in the propellant with increase in pressure.

Effect of manganese dioxide on the thermal decomposition of ammonium perchlorate

Abstract: Thermal decomposition of powdered ammonium perchlorate, catalysed by manganese dioxide (MnO2), has been studied in the low concentration ranges of the catalyst. MnO2 sensitises the thermal decomposition of ammonium perchlorate. The activation energy estimations of catalysed ammonium perchlorate show that the value is about 30 kcal/mol throughout the low and the high temperature regions whereas uncatalysed ammonium perchlorate gives two activation energies, 20 kcal/mol in the low temperature region (280–320°C) and 60 kcal/mol in the higher temperature region (350–390°C). This behaviour has been explained on the basis of an electron transfer process. The effectiveness of MnO2 in the thermal decomposition further increases on pre-heating the sample at 50°C for two weeks; manganese ions enter the ammonium perchlorate lattice during the process of pre-heating.

Effect of the addition of ultrafine aluminum powders on the rheological properties and burning rate of energetic condensed systems

Abstract: The effect of small additives (1.25–5.00%) of ultrafine aluminum powders (UFAP) on the rheology and combustion of model four-component energetic condensed systems is studied. It is found that the addition of UFAP decreases the temperature of HMX decomposition. Small additives of UFAP increase the burning rate of model energetic condensed systems and decrease the exponent ν in the burning rate law without deteriorating the rheological characteristics of the model propellants.

Hazard Characterization of Uncoated and Coated Aluminium Nanopowder Compositions

Abstract: The thermal properties of various uncoated and coated aluminum nanopowders and their effects on the thermal stability, outgassing behavior, and electrostatic discharge sensitiveness of various energetic materials were studied. These aluminum nanopowders had a mean particle size of 20-120 nm. The coated samples had a layer of 7-25% mass of polymer. The thermal behavior of the aluminum nanopowders in air was determined, and the effects of the particle size and the coating on the reactivity of aluminum nanopowders are discussed. Aluminium nanopowders are very reactive in the presence of water, resulting in aging problems. The coating of polymer has a minor effect on the reactivity of aluminum nanopowders with water. On the other hand, the results from an aging study show that the coated aluminum nanopowder is more stable than the uncoated nanopowder in humid atmospheres. The addition of some coated aluminum nanopowders lowers the onset temperatures of cyclotrimethylenetrinitramine, trinitrotoluene, and glycidyl azide polymer by ∼20°C. Outgassing results obtained for various cyclotrimethylenetrinitramine/aluminum mixtures at 100° C show that the uncoated Al120 enhances the low-temperature solid-phase decomposition of cyclotrimethylenetrinitramine. The addition of uncoated aluminum nanopowders has previously been shown to increase the electrostatic discharge sensitiveness of both ammonium dinitramide and ammonium perchlorate to ignition energies that can easily be carried by a human body. In contrast, the coated aluminum nanopowders do not appear to sensitize ammonium dinitramide and ammonium perchlorate toward electrostatic discharge, which suggests that the coatings can effectively prevent the sensitization effect.

Ammonium perchlorate-based composite solid propellant formulations with plateau burning rate trends

Abstract: This paper presents burning rates as a function of pressure of several propellant formulations based on ammonium perchlorate (AP) and hydroxyl-terminated polybutadiene cured by isophorone diisocyanate, many of which exhibit significantly low (nearly zero or negative) values of the pressure exponent of the burning rate in distinct pressure ranges, termed as plateau burning rate trends. The propellants contain a bimodal distribution of AP particles with the size of the coarse and fine particles within narrow ranges whose mean values are widely separated. Two mean sizes of fine particles were considered for the propellant formulations in the present work, namely, 5 and 20 µm. These choices are based on the mid-pressure extinction behavior exhibited by the matrix of fine AP and binder contained in the propellants but when tested alone over a wide range of fine AP size and pressure. The propellants that include the fine AP/binder matrixes exhibiting a mid-pressure extinction, in turn, exhibit the plateau burning rate trends within the corresponding pressure ranges. A plateau is also observed at elevated pressures in the burning rates of some formulations, which is related to the diminishing relative importance of the near-surface leading-edge region of the oxidizer/fuel diffusion flame in the gas-phase combustion zone. The choice of the coarse AP size influences the exact pressure range within the mid-pressure extinction domain of the matrix where the propellant exhibits the plateau burning rate trends.

Studies on a Novel Thermoplastic Polyurethane as a Binder for Extruded Composite Propellants

Abstract: Extruded composite propellant (ECP) is an entirely new thrust area in the development of composite propellants within India. These are based on high-density thermoplastic elastomers as a propellant binder with ammonium perchlorate (AP) as an oxidizer and aluminum (Al) as a metallic fuel. Thus, this class of propellant not only provides higher energy but also yields higher density impulse. There are no pot life problems as with conventional slurry cast composite propellants because the binder used is thermoplastic in nature and hence can be recycled. ECP can take up solid loadings up to 90% and have very good dimensional stability. The present article reports evaluation of a thermoplastic polyurethane, viz. Irostic, as a binder for extruded composite propellants. The polymer was characterized completely before use. The feasibility of propellant processing has been studied and processing parameters have been established. Around 50 propellant formulations are processed for selection and optimization of plast...

Synthesis and characterization of Cu-Cr-O nanocomposites

Abstract: Cu-Cr-O nanocomposites that can be used as additives for the catalytic combustion of AP(ammonium perchlorate)-based solid-state propellants were synthesized via a citric acid(CA) complexing approach. Techniques of TG-DTA, XRD as well as TEM were employed to characterize the thermal decomposition procedure, crystal phase, micro-structural morphologies and grain size of the as-synthesized materials respectively. The results show that well-crystallized Cu-Cr-O nanocomposites can be produced after the CA-Cu-Cr precursors are calcined at 500°C for 3 h. Phase composition of the as-obtained Cu-Cr-O nanocomposites depends on the molar ratio of Cu to Cr in the starting reactants. Addition of the as-synthesized Cu-Cr-O nanocomposites as catalysts enhances the burning rate as well as lowers the pressure exponent of the AP-based solid-state propellants considerably. Noticeably, catalyst with a Cu/Cr molar ratio of 0.7 exhibits promising catalytic activity with high burning rate and low pressure exponent at all pressures, due to the effective phase interaction between the spinel CuCr2O4 and delafossite CuCrO2 contained in the as-synthesized Cu-Cr-O nanocomposites.

Burning of Aluminized Solid Rocket Propellants: from Micrometric to Nanometric Fuel Size

Abstract: A survey is offered of the present status of microaluminized propellants industrially used worldwide in most space applications, and also new directions are pointed out making profitable use of the nanoaluminized propellants meanwhile tested in advanced international laboratories. The survey is limited to formulations with inert binders. Different industrialand research-type of solid rocket propellants, mainly but not only, of the family AP/Al/HTPB were experimentally analyzed at the Space Propulsion Laboratory of Politecnico di Milano. In general, they feature the same nominal composition but implement different grain size distributions of the oxidizer or metal fuel. The basic properties of all formulations were compared to that of a standard 68/18/14 propellant already certified for flight. In order to test their possible eligibility in terms of performance for future launchers, steady ballistic properties in terms of burning rate and flame structure were studied by a variety of experimental techniques ranging from high-speed and high resolution digital video recording to chemo-physical analyses of the solid combustion residues. Surprising differences were revealed in the flame structure of apparently similar formulations. In turn, this allowed shedding new light on the complex phenomena governing metallized solid rocket propellant burning and thus acquiring improved prediction capabilities of motor performance. Nomenclature Roman symbols Al = metallic aluminum Al2p = aluminum oxide content in XPS analysis Al2O3/Al = aluminum oxidation efficiency Alox = aluminum oxide at.% = atomic concentration C1s = carbon content in XPS analysis C2Cl4 = inert liquid Cl2p = chlorine content in XPS analysis Dp = particle diameter, μm D43 = mass mean diameter, μm DAP = mean ammonium perchlorate grain size, μm Is = specific impulse, s Is,ideal = ideal (adiabatic thermochemical equilibrium) specific impulse, s n = steady burning rate pressure sensitivity O1s = oxide content in XPS analysis p = pressure, bar qr = radiant flux, W/cm rb = steady burning rate, mm/s tign = ignition time, ms (t*)cc = average residence time in combustion chamber, ms (Vcc/Ab)1/2 = combustion chamber free volume / burning area ratio at half burning time, m Greek symbols ΔIs = specific impulse loss, s ηc* = efficiency of characteristic velocity, % ηcs = efficiency of thrust coefficient, % ηIs = efficiency of specific impulse, % ρcc = combustion chamber gas mixture density, g cm ρp = propellant density, g cm α-Al2O3 = stable phase alumina or Corundum Abbreviations AP = Ammonium Perchlorate CCPs = Condensed Combustion Products HTPB = Hydroxyl-Terminated Polybutadiene MOPs = Micrometric Oxide Particles SEM = Scanning Electron Microscopy SOPs = Smoke Oxide Particles TMD = Theoretical Maximum Density XPS = X-Ray Photoelectron Microscopy XRD = X-Ray Diffraction 1

Two-Dimensional Modeling of AP/HTPB Utilizing a Vorticity Formulation and One-Dimensional Modeling of AP and ADN

Abstract: TWO-DIMENSIONAL MODELING OF AP/HTPB UTILIZING A VORTICITY FORMULATION AND ONE-DIMENSIONAL MODELING OF AP AND ADN Matthew L. Gross Department of Chemical Engineering Doctor of Philosophy This document details original numerical studies performed by the author pertaining to the propellant oxidizer, ammonium perchlorate (AP). Detailed kinetic mechanisms have been utilized to model the combustion of the monopropellants AP and ADN, and a two-dimensional diffusion flame model has been developed to examine the flame structure above an AP/HTPB composite propellant. This work was part of an ongoing effort to develop theoretically based, a priori combustion models. The improved numerical model for AP combustion utilizes a “universal” gasphase kinetic mechanism previously applied to combustion models of HMX, RDX, GAP, GAP/RDX, GAP/HMX, NG, BTTN, TMETN, GAP/BTTN, and GAP/RDX/BTTN. The universal kinetic mechanism has been expanded to include chlorine reactions, thus allowing the numerical modeling of AP. This is seen as a further step in developing a gas-phase kinetic mechanism capable of modeling various practical propellants. The new universal kinetic mechanism consists of 106 species and 611 reactions. Numerical results using this new mechanism provide excellent agreement with AP’s burning rate, temperature sensitivity, and final species data. An extensive literature review has been conducted to extract experimental data and qualitative theories concerning ADN combustion. Based on the literature review, the first numerical model has also been developed for ADN that links the condensed and gas phases. The ADN model accurately predicts burning rates, temperature and species profiles, and other combustion characteristics of ADN at pressures below 20 atm. Proposed future work and modifications to the present model are suggested to account for ADN’s unstable combustion at pressures between 20 and 100 atm. A two-dimensional model has been developed to study diffusion in composite propellant flames utilizing a vorticity formulation of the transport equations. This formulation allows for a more stable, robust, accurate, and faster solution method compared to the Navier-Stokes formulations of the equations. The model uses a detailed gas-phase kinetic mechanism consisting of 37 species and 127 reactions. Numerical studies have been performed to examine particle size, pressure, and formulation effects on the flame structure above an AP/HTPB propellant. The modeled flame structure was found to be qualitatively similar to the BDP model. Results were consistent with experimental observations. Three different combustion zones, based on particle size and pressure, were predicted: the AP monopropellant limit, the diffusion flame, and a premixed limit. Mechanistic insights are given into AP’s unique combustion properties.

Production and Characterization of Nano-Aluminum and its Effect in Solid Propellant Combustion

Abstract: Nano-aluminum particles were produced by the electrical wire explosion method at this laboratory. The size and shape of the particles were measured using a transmission electron microscope (TEM). Aluminum wires are exploded by application of high voltage, to yield particles of size around 40 nm. The X-ray diffraction (XRD) results also confirm that the powder formed by the above process as aluminum with an average size of 42 nm. Previous studies on ultrafine-aluminum applied to solid propellants have tested a particle size not less than about 100 nm. The thermal characteristics were analyzed using thermo gravimetric and differential thermal analyses (TG-DTA). The composition of the material was characterized by energy dispersive angle X-ray (EDAX) analysis. The low pressure deflagration limit (LPDL) tests were carried out for dry-pressed pellets of the nanoaluminum or normal aluminum with ammonium perchlorate (AP). Sandwich burning tests of the nano-aluminum and normal aluminum added to the middle lamina of binder were also carried out. It showed that the addition of nano-aluminum marginally increased the burning rate at elevated pressures and higher lamina thicknesses. Composite propellant formulations were developed out with a bimodal size distribution of AP particles, with the baseline non-aluminized formulations exhibiting plateau burning rate trends. Burning rate studies of the non-aluminized, nano-aluminized, and normal aluminized propellants were carried out. It was found that the burning rate of the nano-aluminized propellants increased by 100% compared to normal aluminized propellants. In the nano-aluminized propellants, the plateau effects in the burning rate of the corresponding non-aluminized propellants in the intermediate pressure range were removed, but significantly low pressure-exponents were observed at elevated pressures. The results point out that the nearly complete combustion of nano-aluminum near the propellant burning surface actually controls the propellant burning rate. The nano-aluminum combustion is diffusion-limited at elevated pressures, and hence, results in significantly low pressure-exponents of burning rate in that pressure range.

Burning Rate Calculations of Wide Distribution Ammonium Perchlorate Composite Propellants

Abstract: A combustion model is developed to calculate the burning rates of wide distribution ammonium perchlorate composite propellants. The model is based on the BDP (BecksteadDerr-Price) type multiple flames concept and incorporates separate surface temperatures for oxidizer and binder. Price-Boggs-Derr model of AP self deflagration is used to assure better predictions of oxidizer surface temperature and burning rates. Burning rates are calculated for multimodal oxidizer propellant formulations with a wide distribution of particle sizes. Computed rates are in good agreement with the experimental data of our own experimental test formulations. The predictions in terms of burning rate and pressure exponent are improved compared to earlier models at high pressure and with wide distribution of particle sizes.

Modeling of Propellants Containing Ultrafine Aluminum

Abstract: In the study of heterogeneous propellants that contain large amounts of fine aluminum and ammonium perchlorate, it is appropriate to distinguish between the matrix (a homogenized blend of fine particles and binder) and larger particles that are embedded in this matrix. Then the burning properties of a pure matrix are required. We construct a one-dimensional model for this purpose. Key ingredients include the determination of the thermal conductivity and pyrolyis law of the matrix, and an accounting of the radiation field generated by the fine aluminum in the gas phase. Experimental results of Dokhan et al. ("The Ignition of Ultra-Fine Aluminum in Ammonium Perchlorate Solid Propellant Flames," AIAA Paper 2003-4810, July 2003) are used for calibration and in comparisons.

Effect of pretreatment on the sublimation of ammonium perchlorate

Abstract: The effects of pretreatments on the sublimation of pure ammonium perchlorate (AP) were studied by differential thermal analysis. The addition of inorganic salts (doping), or preheating, lead to desensitisation of the sublimation process, whereas it was sensitised by precompression. Sublimation increased with decrease in the particle size of the AP from 500 to 200 microns, but decreased with a further decrease in size from 200 to 100 microns. The results are interpreted in terms of gross imperfections and strain in the AP crystals.

Synthesis, Evaluation, and Formulation Studies on New Oxidizers as Alternatives to Ammonium Perchlorate in DoD Missile Propulsion Applications

Abstract: : Perchlorate is found in groundwater and drinking water throughout the United States. This contamination is primarily attributed to the use of ammonium perchlorate in the solid fuel for rockets and missiles. The objective of the program is to develop environmentally benign solid rocket propellant formulations that do not rely on the use of ammonium perchlorate (AP) as an oxidizer. This objective supports the goal of reducing future AP contamination in groundwater by reducing the need for production and use of AP as an oxidizer in solid rocket motors. The propellants developed must match current performance and hazards to meet the objective. To formulate propellants that don't rely on AP, combinations of oxidizers must be exploited. We selected four new supplemental oxidizers to focus on initially. These include the inorganic oxidizer ammonium di(nitramido) amine (ADNA); the cyclic nitramine/gem-dinitro compounds such as 1,3,5,5-tetranitrohexahydropyrimidine (DNNC) and 1,3,3,5,7,7-hexanitro-1,5- diazacyclooctane (HCO) and by adding the dinitroethylene attachment to nitramide functions as seen in diammonium di(nitramido) dinitroethylene (ADNDNE). The four compounds are predicted to have a low lipophilic nature. This favors migration to surface water or ground water but also indicates these compounds would not bioconcentrate into aquatic organisms or biomagnify within the food chain. Direct toxicity to aquatic organisms is also predicted to be very low.

Gas generant composition for gas actuator for activating safety device and gas generator for gas actuator using the same

Abstract: Disclosed is a gas generant composition for a gas actuator used for activating a safety device, which contains (A) a nitrogen-containing organic compound, (B) a metal nitrate and/or a perchlorate, (C) a water-soluble polymer binder, and (D) a magnetic material. When compared with the conventional gas generant compositions, this gas generant composition is excellent in combustibility under low pressure conditions and reduced in CO gas generation during combustion. In this gas generant composition, (D) the magnetic material is preferably composed of a magnetic iron oxide. It is also preferable that (A) the nitrogen-containing organic compound is composed of one or more substances selected from nitroguanidine, guanidine nitrate, bitetrazole, azobistetrazole and 5-aminotetrazole; (B) the metal nitrate is composed of a metal salt selected from alkali metals and alkaline earth metals, while the perchlorate is composed of ammonium perchlorate or potassium perchlorate; (C) the water-soluble polymer binder is composed of a mixture of hydroxypropyl methylcellulose (HPMC) and a polyacrylamide; and (D) the magnetic iron oxide has a spinel crystal structure.

Fast analysis method of ammonium perchlorate particle size in solid propellant

Abstract: The invention relates to a rapid analysis method for granularity of ammonium perchlorate in solid propellant. It includes the following steps: collecting ammonium perchlorate sample of purity over 99.5% by screen method; gathering sample spectrum and building database; selecting representative sample by math method and taking preprocess, building standard sample model by using the wave length information of amino between first level double frequency absorption peak of 6463cm-1 and combining frequency absorption peak of 4680cm-1; comparing the granularity of pre-testing to that of sample to judge whether it is qualified; if it is not qualified, judging whether it is out-drop point; if it is out-drop point, taking second judgment; if not, returning to the first step. The invention is easy to operate and has rapid analyzing speed.

Specific features of thermal decomposition of ammonium perchlorate subjected to γ radiation

Abstract: Results of studying thermal decomposition of ammonium perchlorate (AP) samples in the original form and after irradiation by γ-quanta of 60Co by methods of differential scanning calorimetry and dynamic thermogravimetry with heating rates b = 0.1–0.3 K/sec are described. Irradiation is performed in air at a temperature of 298 ± 2 K and a dose rate of ≈0.2 Gy/sec in the range of absorbed doses D = 0–150 kGy. Preliminary irradiation is demonstrated to lead to substantial transformations of the pattern of thermal decomposition of ammonium perchlorate in the dynamic regime of heating: the single-stage process of decomposition of non-irradiated samples proceeding at b = 0.107 K/sec in the temperature range of 625 to 743 K is replaced by a multistage process. At D = 150 kGy, exothermal transformations accompanied by noticeable losses of sample mass are observed starting from 473 K. Within experimental errors, the total thermal effect of AP decomposition is found to be independent of the absorbed dose and amounts to −1150 kJ/kg on the average.

Environmental Screening Assessment of Perchlorate Replacements

Abstract: : A screening level assessment of the fate, transport, and toxicity of four potential replacements for perchlorate was performed. Resulting data will allow for evaluation and minimization of the potential environmental liability associated with the use of energetic compounds as propellants. This report details methods used and assessment findings. Inorganic oxidizer ammonium di(nitramido)amine (ADNA); cyclic nitramine/ gem-dinitro compound 1,3,5,5-tetranitrohexahydropyrimidine (DNNC); 1,3,3,5,7,7-hexanitro-1,5-diazacyclooctane (HCO); and diammonium di(nitramido)dinitroethylene (ADNDNE) were evaluated. Their respective analogue compounds also were evaluated: ammonium dinitramide (ADN); hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX); octahydro-1,3,5,7- tetranitro-1,3,5,7-tetrazocine (HMX); and 1,1-diamino-2,2-dinitroethene (FOX-7). Evaluations of ammonium perchlorate (AP) provide a point of comparison. From an environmental fate and transport perspective, it appears ADNA, ADNDNE, DNNC, and HCO may have some characteristics similar to AP. However, it is possible HCO and DNNC are much less soluble in water than AP, thereby reducing the likelihood of environmental transport. It also is anticipated that ADNA, ADNDNE, DNNC, and HCO will readily photodegrade. However, rates of degradation in subsurface soil, groundwater, deep surface water, and sediment appear highly variable and may be dependent on covariables not evaluated for this assessment. Because of uncertainty with the model predicted results, recommendations for additional analysis, which could yield compound-specific data and reduce uncertainty, are provided.

Propellant composition for gas generator using phase stabilized ammonium nitrate and oxamide

Abstract: A propellant composition is provided to exhibit a low flame temperature and a low combustion rate, to ensure excellent ignitability and combustion stability, and to generate clean fuel gas having low corrosion or an extremely low content of combustion residues. A propellant composition includes 25-60wt% of ammonium nitrate phase-stabilized with zinc oxide, 10-15wt% of oxamide, 10-15wt% of polycaprolactone polymers, and 10-20wt% of butanetriol trinitrate, trimethylol trinitrate, or diethyleneglycol dinitrate. The propellant composition further comprises less than 20wt% of trimethylene trinatramine, less than 10wt% of ammonium perchlorate, and 0.1-1.0wt% of carbon black.

The Effect of Aluminum and Ammonium Perchlorate Content on Temperature Sensitivity, Mechanical Properties and Performance of HTPB Propellants

Abstract: This paper describes the effect of aluminum content variation of HTPB (hydroxyl terminated polybutadiene) propellants on temperature sensitivity, mechanical properties and performance values. Aluminum (Al) content was applied as 16, 18 and 20 percent to the propellant compositions and those compositions were tested at small test motors with three different propellant area ratios (K=200, 250 and 300) by keeping the propellant grain at three different temperatures (231, 258 and 323 K). As a result of this, a relationship such as P=aesT was determined with different coefficients for each of the three compositions and propellant area ratios. The lowest temperature sensitivity value was obtained for the composition containing 20% Al and 65% AP. The second relation as P=bKy was derived for three propellants and temperatures. The highest pressure was found with the K value of 300 for the propellant including 16% Al and 69% AP at 323 K. The third relationship such as r=cPn was also determined for three propellant compositions and temperatures. It was observed that the propellant having 16% Al and 69% AP had the highest burning rate at 323 K. The highest maximum tensile stress and elongation values were obtained for the propellants including 20% Al and 16% Al respectively. Evaluation of performance values for those propellants exhibits that the maximum characteristic velocity value is attained for the propellant containing 16% Al and 69% AP.

Effect of ammonium perchlorate grain size on combustion of a selected composite solid propellant

Abstract: The heterogeneous propellants consisting of Ammonium Perchlorate (AP) particles imbedded in a Hydroxyl Terminated Polybutadience (HTPB) are widely used in solid rocket industries. In this study, the effect of AP particles diameter and the random distribution with the HTPB on the burning of such propellant is presented. A mathematical model which describes the unsteady burning of a heterogeneous propellant by simultaneously solving the combustion fields in the gas phase and the thermal field in the solid phase with appropriate jump condition across the gas/solid interface is developed. The gas-phase kinetics is represented by a two-step reaction mechanism for the primary premixed flame and the primary diffusion flame between the decomposition products of the HTPB and the oxidizer AP. The propagation of the unsteady non-planer regression surface is described, using the Essentially-Non-Oscillatory (ENO) scheme with the aid of the level set strategy. The results show that the large AP particle diameter has a marked effect on the combustion surface deformation and on the burning rate as well. Therefore, modeling of the condensed phase process is mostly conducted on AP. Moreover, the effect of various parameters on the surface propagation speed, flame structure, and the burning surface geometry is obtained.

Electrolyte and method of producing the same

Abstract: An electrolyte and method of producing the same. In one embodiment, the electrolyte includes water, ascorbic acid, a phosphorous donor, ammonium perchlorate, ferrous perchlorate, cobalt perchlorate, and a buffering agent.

Convective burning of pressed aluminum-ammonium perchlorate charges

Abstract: The convective burning of pressed aluminum-ammonium perchlorate (AP) charges with a porosity of 7 to 18% was studied. The experiments were performed at pressures of up to 300 MPa in a constant volume bomb provided with means for recording pressure-time diagrams, and in a nozzle setup equipped with a streak photocamera and piezoelectric pressure gauges. In contrast to loose-packed-density charges, which are highly explosive, the burning of pressed aluminum-AP charges propagates without marked acceleration, with a moderate velocity and a relatively slow rise in pressure in the bomb. The basic regularities were studied, and the key factors that determine the characteristics of convective burning, such as the aluminum particle shape (when a finely dispersed spherical-particle powder was replaced by a flaky aluminum powder with the same speciic surface area, the convective burning velocity decreased by more than an order of magnitude), ratio of mixture components, and charge porosity, were identified. The effects of the ammonium perchlorate particle size, an organic additive, and the ignitor mass were also studied. The experimental data were analyzed by invoking numerical modeling. The calculations were performed using a program developed earlier based on a model of the convective burning of aluminum-AP mixtures. The calculation results, which were in qualitative agreement with the available experimental data, made it possible to explain the main experimentally observed regularities. The compositions tested and the results obtained are of considerable interest for designing convective-burning charges for multipurpose pulse engines and thermo-and gas generators with operation durations from a few milliseconds to several tens of milliseconds.