Showing papers on "Ammonium perchlorate published in 2001"

Fuel Regression Rate in Hydroxyl-Terminated-Polybutadiene/ Gaseous-Oxygen Hybrid Rocket Motors

Abstract: The results of a systematic experimental investigation on the methods of enhancing the regression rate in hydroxyl-terminated polybutadiene (HTPB) fuel used in an HTPB/gaseous oxygen hybrid motor are presented The effects of the addition of ammonium perchlorate (AP) or aluminum in the fuel, the variation of oxidizer ‐fuel ratio, and the variation of characteristic dimensions of fuel grain are presented For the extents of the parametric variations considered, while the addition of AP and/or Al and the reduction of grain port diameter enhance the regression rate, the effect due to the latter is the most signie cant one Furthermore, the regression rate increases along theaxis, and it becomes essentially constant in the port region corresponding to a fuel-rich composition The possible physical processes for all of these behaviors are discussed The experimentally obtained exponents of the variables for regression rate (oxidizer mass e ux and port diameter ) are found to be signie cantly different from those of the conventional theory The similarity between the fuel regression rate equation used in solid-fuel ramjet and that obtained in hybrid motor is discussed

Random Packs and Their Use in Modeling Heterogeneous Solid Propellant Combustion

Abstract: It isshown thatrandom packsofspheresofvarioussizescan beconstructed thatmodelammonium ‐perchloratein-binder propellants in thesense that both thesize distributions and thepacking fractions of industrial propellant packs can be matched. Strategies for dealing with fractional numbers of large particles are addressed, as are strategies for dealing with a large number of very e ne particles (e ne powder). Fine powder is necessary in a threedimensional pack to achieve the required stoichiometric ratio of ammonium perchlorate to fuel binder, but is not necessary in a two-dimensional (disk) pack. Some preliminary calculations of the two-dimensional combustion e eld supported by a disk pack are presented, in which full coupling between the gas phase, the condensed phase, and the retreating nonplanar propellant surface is accounted for. Nomenclature D1;2 = reaction rate constants dj = mean diameter of particles E1;2 = activation energies L = length of a pack edge N = total number of particles Nj = number of particles in the jth class n j = number fraction of particles in the jth diameter classs n1;2 = pressure exponents Ru = universal gas constant R1;2 = reaction rates rb = surface regression rate T = temperature Vj = volume of particles in the jth class v j = volume fraction of particles in the jth class X = mass fraction of ammonium perchlorate (AP) Y = mass fraction of fuel binder Z = mass fraction of AP decomposition products ´ = surface function A = surface location A = level set function dee ning the pack

Gas generating compositions

Abstract: A low-solids gas generating composition, which is a mixture of a fuel selected for the group consisting of cellulose, cellulose acetate, hexamine, and mixtures thereof, and an oxidizer selected from the group consisting of ceric ammonium nitrate, lithium nitrate, lithium perchlorate, sodium perchlorate, phase stabilized ammonium nitrate, a combination of ammonium nitrate with potassium nitrate, potassium perchlorate, or mixtures thereof, such that the combination is a solid solution, a mixture of ammonium perchlorate and at least one alkali metal salt, and mixtures thereof. The combination of ammonium nitrate with other salts in solid solution is intended to phase stabilize the ammonium nitrate. The oxidizer-fuel mixture is within about 4 percent of stoichiometric balance. Useful alkali metal salts include lithium carbonate, lithium nitrate, sodium nitrate, potassium nitrate, and mixtures thereof. The preferred oxidizers for the gas generating composition of the invention are ceric ammonium nitrate, lithium nitrate, lithium perchlorate, sodium perchlorate, a mixture of ammonium perchlorate and at least one alkali metal salt, and mixtures thereof. In addition, the gas generating composition may include an energizing agent, such as RDX or HMX. The gas generating composition of the invention may further comprise sub-micron fumed silica to reduce moisture contamination and serve as a processing and powder flow aid and/or a binder, and may be in the form of pressed pellets, grains, or granules.

Gas-generating compositions

Abstract: A gas-generating composition having superior gasification rate, appropriate combustion rate, and suppressed carbon monoxide generation. The gas-generating composition includes ammonium nitrate, metal oxyacid salt, ammonium perchlorate, and combusting component. A basic combustion residue derived from the metal oxyacid salt is neutralized by hydrogen chloride derived from the ammonium perchlorate, thereby substantially neutralizing combustion residue of the gas-generating composition.

Aging of HTPB/AP‐based composite solid propellants, depending on the NCO/OH and triol/diol ratios

Abstract: Aging behavior of hydroxyl-terminated polybutadiene/ammonium perchlorate (HTPB/AP)-based composite solid propellants was studied as a function of crosslink density, which is predominantly determined by the molar ratio of diisocyanate to total hydroxyl (NCO/OH ratio) and the molar ratio of triol to diol (triol/diol ratio). For this purpose, 16 propellant samples with different compositions were prepared by changing the NCO/OH ratio as 0.81, 0.82, 0.83, and 0.85 for each triol/diol ratio of 0.07, 0.09, 0.11, and 0.13, and subjected to an accelerated aging at 65°C. The changes in the mechanical properties were monitored throughout the aging period. In the initial part of the aging period, a sharp increase in stress, modulus, and hardness values and a sharp decrease in strain values were observed for all the propellants. At further stages of aging, only slight changes were observed in the mechanical properties. Concerning the aging criterion as reduction in the strain capability more than the half of the initial value, the propellants with respective NCO/OH-triol/diol ratios of 0.81–0.09, 0.85–0.09, 0.81–0.13, 0.83–0.13, and 0.85–0.13 can be considered to be aged with time. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 959–964, 2001

Ammonium perchlorate–binding poly(allylamine hydrochloride) hydrogels for wastewater remediation

Abstract: Systems that are capable of removing highly toxic anions from wastewater effluents, even at extremely low concentrations, are a major need in the defense industry. This study reports on the features of two new batch and continuous-flow sorption processes with regard to ultimate removal and recovery of the perchlorate (ClO) anion from ammonium perchlorate (NH4ClO4) wastewater. The sorbent developed is a crosslinked poly(allylamine hydrochloride) (PAA·HCl) polymeric hydrogel. The pH-sensitive PAA·HCl hydrogels were synthesized by chemically crosslinking a solution of linear PAA·HCl chains with epichlorohydrin (EPI). The perchlorate-binding capacity of the polymer gels was measured in standard solutions and studied as a function of gel synthesis parameters. Equilibrium perchlorate loadings of 5770 ± 870 mg ClO/g gel were calculated from measurement of the decrease in perchlorate concentration in aqueous standard solutions using UV-Vis spectrophotometry. Batch experiments in wastewater originating from the Naval Surface Warfare Center (NSWC) Indian Head Division showed that perchlorate concentrations decreased by 85%. Preliminary lab-scale packed-column experiments in wastewater achieved up to 40% reduction in total perchlorate content. The regeneration ability of the gels was demonstrated by release of the bound perchlorate anions, upon washing with a 1N NaOH solution, providing opportunities to recover and reuse the hydrogel over multiple regeneration cycles. The PAA·HCl hydrogels are demonstrated to be appropriate materials for treating wastewaters that contain ammonium perchlorate. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2073–2083, 2001

Gas generant composition with coolant

Abstract: A low-solids gas generating composition and a method of producing a gas. The gas is produced by combusting a mixture of a fuel selected from the group consisting of guanidine nitrate, nitroguanidine, cellulose, cellulose acetate, hexamine, 5 amino-tetrazole, 5 nitro-uracil, guanidine salt of 5 nitro-uracil, and mixtures thereof, an oxidizer selected from the group consisting of ceric ammonium nitrate, strontium nitrate, basic copper nitrate, a mixture of ammonium perchlorate and at least one alkali metal salt, and mixtures thereof, and a cupric oxalate hemi-hydrate coolant. The oxidizer-fuel mixture is within about 4 percent of stoichiometric balance, and the low-solids gas generating composition produces no more than about 0.082 cubic centimeters of solids per gram of gas generating composition on combustion.

High energy propellant with reduced pollution

Abstract: This invention relates to energetic compositions, which offer increased performance in conjunction with a total absence of hydrogen chloride in the combustion products. The formulation avoid the use of halogen based oxidizers to prevent the formation of halogen based byproducts. The formulations disclosed herein use ammonium dinitramide as a primary oxidizer, which is a more energetic molecule than ammonium perchlorate. The solid propellant formulations disclosed herein comprise about 5.0 to about 10.0 weight % of at least one energetic binder; about 20.0 to about 35.0 weight % of an energetic plasticizer; about 25.0 to about 45.0 weight % of ammonium dinitramide as a primary oxidizer; about 0.0 to about 20.0 weight % of particulate aluminum having a particle size of about 1 μm to about 60 μm; and about 0.0 to about 20.0 weight % of ultrafine aluminum having a particle size of less than 1 μm. In addition to the ingredients in this basic formulation will be cure catalysts, curatives, crosslinkers, burn rate catalysts and modifiers, thermal and aging stabilizers other such ingredients commonly utilized in solid propellant formulations.

Propellant composition comprising nano-sized boron particles

Abstract: The present invention is a propellant composition comprising from about 2 percent to about 46 percent, by weight, boron particles having a diameter of less than about 500 nanometers. Liquid or gel embodiments of the invention may also include adding the boron particles to a liquid fuel in order to form a liquid fuel system. Examples of such liquid fuels include ethyl ammonium nitrate (EAN), triethyl amine nitrate (TEAN), Cyclotetramethylenetetranitramine (HMX), trinitrotoluene (TNT), jet fuel formula (JP-10), kerosene, RJ-4, or other hydrocarbon based fuels. These liquid fuel systems can be part of bipropellants wherein the liquid fuel system is stored separately from an oxidizing agent and the two are mixed during operation. Examples of oxidizing agents may include nitrogen tetroxide, oxygen, hydrogen peroxide, hydroxyl ammonium perchlorate (HAP), hydoxyl ammonium nitrate (HAN), ammonium perchlorate, ammonium nitrate, ammonium dinitramide (ADN), or a combination of said chemicals. One specific preferred embodiment of the invention comprises a fuel comprising approximately 61.60 percent by weight EAN, approximately 23 percent by weight boron particles having a diameter of less than about 500 nanometers, approximately 3.85 percent by weight ammonium nitrate, and approximately 11.55 percent by weight water coupled with an oxidizing agent comprising approximately 38 percent by weight hydrogen peroxide, approximately 46 percent by weight ammonium nitrate, and approximately 16 percent by weight water. The present invention also comprises a monopropellant formed by adding the nano-sized boron particles to a fuel containing oxygen. Another embodiment of the invention is a solid propellant wherein the nano-sized boron particles are used as a metal fuel component or as a portion of a metal fuel component and are mixed with an oxidizing agent and bound with a binder.

Studies on Combustion of Metallized RDX-Based Composite Modified Double-Base Propellants

Abstract: This paper reports the results obtained during research work carried out on metallized cyclo trimethylene trinitramine (RDX)-composite modie ed double-base (CMDB)propellantswith theaim of realizing superiorburning rates as well as performance Nickel (Ni) and titanium (Ti)-based formulations exhibited burning-rate characteristics superior to those for aluminized (Al) compositions, whereas zirconium (Zr)-based formulations gave the best results An attempt has been made to explain the burning-rate pattern observed on the basis of combustion characteristics of metals Among selected ballistic modie ers, basic lead salicylate (BLS)+Cu2O+carbon black (C-black) combination and copper chromite (Cu-chromite ) gave catalytic effect superior to that of ferric oxide (Fe2O3) and ferric acetyl acetonate (FeAA) Incorporation of 5% ammonium perchlorate (AP) of 5π size augmented the catalytic effect of ballistic modie ers remarkably Thus, RDX (125%)-Zr (175%) CMDB formulation with 5% AP (5π) and two-parts Cu-chromite gave burning rates of the order of 4 ‐21 mm/s in the pressure range of 1‐108 MPa and pressure index value of 066 with Isp (theoretical ) of the order of 241 s To take advantage of pyrophoric nature of Zr and superior heat of combustion of Al, a combination of both the metals was evaluated Composition containing 13% Al and 45% Zr along with 125% RDX in a double-base matrix with 5% AP and two parts of Cu-chromite as additives gave stable combustion in the pressure range of 1 ‐108 MPa (burning rates 4‐18 mm/s) and Isp (theoretical ) of 259 s Kinetic parameters obtained for RDX-CMDB formulations during differential thermal analysis studies (Ea 48 kcal/mole and A 7 :2 £ 10 19 ) established that the RDX decomposition is the rate-controlling step Addition of Al did not have a remarkable effect on the kinetic parameters of thermal decomposition However, Ni/Ti/Zrbrought down Ea and A valuesdrastically, suggesting thatheat feedbackcaused by efe cient combustion near the dee agrating propellant surface ine uences subglobal kinetics and facilitates the decomposition of condensed phase Thermogravimetric and differential scanning calorimetry (DSC) results bring outthatFe2O3 andBLS +Cu2O +C-black do not play a catalytic rolein condensed-phase decomposition, whereas Cu-chromite and FeAA appear to catalyze both gas- as well as condensed-phase reactions

Minimum signature propellant

Abstract: This invention relates to energetic compositions, which offer increased performance in conjunction with a total absence of halogen based oxidizers to eliminate exhaust products, such as hydrogen chloride. The oxidizers of choice are various combinations neat ammonium dinitramide, ammonium dinitramide prills and CL-20, because these oxidizers do not produce halogen containing exhaust products, such as the HCl gas of ammonium perchlorate. The exhaust these novel propellants consist mostly of CO 2 , H 2 O, N 2 , and small amounts of CO. These exhaust species are friendlier and much less hazardous to the environment than those emitted by conventional AP-based propellants. The plasticizers are selected from energetic plasticizers that do not contain halogens, but maintain other desirable properties.

Effect of la2o3, pr2o3 and nd2o3 on the thermal decomposition of ammonium perchlorate

Abstract: The effect of ‘p’ type rare earth oxides with partially filled ‘f’ orbitals like La2O3, Pr2O3 and Nd2O3 on the thermal decomposition of ammonium perchlorate (AP) has been studied using isothermal and non-isothermal methods of thermal analysis. Differential thermal analysis (DTA) and thermogravimetry (TG) results reveal that these oxides influence the thermal decomposition pattern of AP significantly and bring down the decomposition temperature substantially. Isothermal studies showed substantial acceleration of the decomposition of AP with the incorporation of these oxides as little as 0.05%. Isothermal data were analyzed using various kinetic models. The activation energy for the catalyzed decomposition of AP was significantly lower. The catalytic effect is explained on the basis wherein the ‘p’ type oxides act as conduites through metal cation in the electron-transfer mechanism for AP decomposition.

Intermittent burning and its contribution to plateau burning of composite propellants

Abstract: The plateau burning behavior of composite solid propellants consisting of ammonium perchlorate (AP) and hydrocarbon (HC) binder with a bimodal AP particle size distribution (coarse and fine) is examined. The focus is the weak pressure dependence of the propellant burn rate (i.e., a plateau) in an intermediate range of about 2.7-6.9 MPa (-400-1000 psi). The relationship between the appearance of this mid-pressure plateau for a composite propellant and self-extinction during the burning of the corresponding fine AP/binder matrix (i.e., the propellant formulation without the coarse AP particles) is experimentally examined through the study of a compositional array of propellants, sandwiches (two-dimensional propellants) and matrixes. The burning history of the samples was captured with a highspeed digital camera, and surfaces from quenched samples (burning that was self-extinguished or intentionally interrupted) are analyzed using a scanning electron microscope. The combined results indicate the prevalence of intermittent burning of the matrixes as the pressure is varied across the boundary between continuous burning and self-extinction (burn/no-burn boundary). The burning surfaces are marked by extreme threedimensionality coupled with a redistribution of the fine AP particles and the binder. The results point to the need for a more realistic approach to the underlying processes that contribute to plateau burning rate trends in bimodal composite propellants than has been adopted hitherto.

Approximate Method for Calculating the Impact Sensitivity Indices of Solid Explosive Mixtures

Abstract: An approximate method is proposed to calculate the impact sensitivity indices (critical initiation pressure and critical charge thickness) for solid explosive mixtures (explosive compositions and mixtures of an oxidizer with a fuel). The calculation is based on some model concepts of the physicochemical and explosive properties of reactive mixtures. Test calculations of the sensitivity indices were performed for mixtures of HMX and TNT and mixtures of ammonium perchlorate with polymethylmethacrylate (PMMA) and TNT, and the results are compared with data of laboratory experiments on an impactor.

Process of treatment of productive pool and charging

Abstract: oil production industry, treatment of face zone of pool. SUBSTANCE: thermal, gas, chemical, boric and vibration wave actions are used to act on productive pool by way of burning of solid-fuel charge in interval of seam. Acidic treatment of seam is conducted simultaneously with burning of charge. Hydrochloric acid is produced in the form of steam and gas mixture under high temperature and pressure exceeding intraseam values of these parameters directly from materials of solid-fuel charge. Mass of produced hydrochloric acid should amount to 20% of mass of charge as minimum. Components used to manufacture mixtures of solid fuels are utilized in the capacity of materials of charge. Water-soluble salts of perchloric acid, for instance, ammonium perchlorate bonded by combustible components in the form of rubber-like binder are used as oxidizer. Filling agent in the form of powder of burning stabilizer in the amount of not more than 1.5% of mass of charge is utilized. Ratio of length and diameter of central conduit depends on size and composition of charge, temperature and pressure in well. Distances between rows of radial through conduits depend on ratio of length and diameter of central conduit. EFFECT: improved filtration properties of productive pool, raised microjointing and substantially increased penetrability of pool. 5 cl, 1 dwg

Quasi-One-Dimensional Model of Combustion of Sandwich Heterogeneous Solid Propellant

Abstract: The paper describes a quasi-one-dimensional model of combustion of sandwich heterogeneous solid rocket propellant designed to predict the burnup rate of individual components (oxidizer and binder) and the average mass rate of combustion of the entire propellant. This model includes the heat- and mass-transfer and kinetic-gasdynamic processes in the gas phase above the surface of burning solid propellant, as well as the heat-transfer processes in solid material. Included in the calculations are the thermochemical properties of ammonium perchlorate (AP, oxidizer) and of polybutadiene rubber (PBR, fuel). The thermochemical processes are included in the kinetic scheme of two overall chemical reactions involving five effective chemical components. Systematic calculations are performed of the process of solid fuel combustion with different mass ratios of oxidizer to fuel. It is demonstrated that the employed kinetic model of thermochemical processes provides an adequate description of the available experimental data on the rate of combustion of AP- and PBR-based solid propellants.

Quasi-one-dimensional model of combustion of sandwich heterogeneous solid propellant

Abstract: The paper describes a quasi-one-dimensional model of combustion of sandwich heterogeneous solid rocket propellant designed to predict the burnup rate of individual components (oxidizer and binder) and the average mass rate of combustion of the entire propellant. This model includes the heat- and mass-transfer and kinetic-gasdynamic processes in the gas phase above the surface of burning solid propellant, as well as the heat-transfer processes in solid material. Included in the calculations are the thermochemical properties of ammonium perchlorate (AP, oxidizer) and of polybutadiene rubber (PBR, fuel). The thermochemical processes are included in the kinetic scheme of two overall chemical reactions involving five effective chemical components. Systematic calculations are performed of the process of solid fuel combustion with different mass ratios of oxidizer to fuel. It is demonstrated that the employed kinetic model of thermochemical processes provides an adequate description of the available experimental data on the rate of combustion of AP- and PBR-based solid propellants.

Erosive burning of ammonium perchlorate/hydroxyl-terminated-polybutadiene propellants under supersonic crossflows

Abstract: An experimental procedure adopted for measuring the erosive burning in solid propellants under transonic and supersonic crossflow Mach numbers is explained. Three formulations of ammonium perchlorate/hydroxyl-terminated-polybutadiene propellants of different burning rates (6, 9, and 16 mm/s at 5 MPa) were used for the study. The study presents the erosive burning results for a range of crossflow Mach numbers from 0.8 to 1.7. Additionally, the adopted experimental procedure clearly demonstrates the choking station movement in grain ports of nozzleless motors. As observed under subsonic crossflow conditions, in supersonic conditions the following conditions hold: 1) The erosive burning effect increases with the increase in both pressure and free stream velocity of crossflow. 2) The propellants with lower normal-burning rates experience greater erosive burning than those with higher normal-burning rates. Negative erosive burning under supersonic crossflow velocities is identified at low pressures.

Equation of state and temperature measurements for shocked ammonium perchlorate

Abstract: A thermodynamically consistent equation of state (EOS) was developed for unreacted, single-crystal ammonium perchlorate (AP) for shock compression along the [210] and [001] directions The specific heat, cv, the pressure-temperature coefficient, (∂P/∂T)v, and the isothermal bulk modulus, BT, were determined from Hugoniot and isothermal compression curves, along with available data at atmospheric pressure The mechanical response of each orientation of the AP crystal was modeled as an isotropic elastic-plastic solid Above the HEL, the rate dependent yielding of AP was described with a simple overstress model Time-resolved Raman spectroscopy experiments were carried out to obtain temperatures in the shocked state These temperature measurements were used to constrain the values of various EOS parameters

High thrust solid propellant

Abstract: PROBLEM TO BE SOLVED: To exhibit the performance of hexanitrohexaazaisowurtzitane at its maximum in applying it to a solid propellant. SOLUTION: Hexanitrohexaazaisowurtzitane(HNIW) and ammonium perchlorate(AP) are combinedly used as solid oxidants. The formulation ratio of HNIW/AP is 1.5 to 5. When metal powder is also used together, if necessary, the specific impulse and combustion temperature increase in compartson with the case where HNIW is singly used as an oxidant and also caking of the oxidant powder is decreased.

Mathematical Combustion Model of a Two–Component Gas Suspension Including a Powder Combustible and a Powder Oxidizer

Abstract: A mathematical model of the ignition and combustion of aluminum and ammonium perchlorate powders in a propulsion system that takes into account their polydisperse distribution and the difference between the gas and disperse–phase velocities and temperatures is developed. The effect of the pressure, the ratios between the components, and the dispersivity of aluminum particles on the structure of a gas–disperse flame, the basic characteristics of the combustion of a gas suspension, and the completeness of propellant combustion is studied.

An explosive water-containing gel-like suspension

Abstract: An explosive water-containing gel-like suspension as additional oxidizer contains sodium nitrate, and/or calcium nitrate, and/or ammonium perchlorate and/or potassium perchlorate. As active organic fuel the suspension contains also monomethylamine nitrate and/or monomethylammonijum nitrate and/or hexamine nitrate and/or carbamide nitrate and/or dimethylamine nitrate. As calorific fuel the suspension contains powdered aluminium and/or silicon and/or coal with particles size less than 200 µm, and/or rubber scrap with particles size less than 2 mm. As sensitizer the suspension contains also aluminium powder and/or perlite sand and/or glass microspheres.

A Numerical Study of an Off-Stoichiometric Flame on Propellant Combustion

Abstract: Presented is an unsteady propellant model and results for a quasi-homogenous mixture. This model is used in the understanding of the oscillatory burning characteristics of a propellant containing two ingredients with different kinetic parameters with an off-stoichiometric flame. Ammonium perchlorate and HTPB were used as a basis for the kinetic parameters to represent pocket propellant formulations. The model is a solution to both the energy and species equations in the solid and gas phases. The propellants were simulated to be burning at 20 atm and perturbed by an oscillating pressure field. Simulations were performed on propellants with oxidizer fuel ratios of 95/5, 90/10, 80/20, and 70/30. The first three cases only showed what is thought to be a classic thermal relaxation response. However, he results indicate that for the fuel rich propellant (oxidizer fuel ratio of 70/30) that a strong natural response around 40 Hz was present at this pressure. Other simulations were used to determine that the composition of the gas phase varied over time as well as the heat feedback to the surface. The natural instability is thought to occur due to a heat feedback loop between the solid and gas phased due, in part, to the off stoichiometric premixed flame.