The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Michael G Leadore - One of the best experts on this subject based on the ideXlab platform.
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mechanical reponse of future combat systems fcs high energy Gun Propellants at high strain rate
2002Co-Authors: Michael G LeadoreAbstract:Abstract : Five lots of Future Combat Systems high-energy Gun Propellants were tested in uniaxial compression at high-strain rate. A production lot of JA2 that is currently used in the M865 round was also tested for comparison purposes. The materials were tested for comparison purposes. The materials were tested while conditioned at temperatures of 21 deg, 63 deg, and -32 deg C. The materials were taken to ^60% strain using a deformation rate of 1.3 m/s. The stress at failure, strain at failure, compressive modulus, failure modulus, incremental energy density, and the fracture assessment values were recorded for each test.
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mechanical properties of aerojet thiokol and ja2 high energy Gun Propellants at 1 5 m s deformation rate
2002Co-Authors: Michael G LeadoreAbstract:Abstract : Five lots of high-energy Gun Propellants were tested in uniaxial compression at temperatures of 21 deg, 63 deg, and - 32 deg C. The materials were taken to 60% strain using a deformation rate of 1.5 m/s. The stress at failure, strain at failure, compressive modulus, failure modulus, incremental energy density, and the fracture assessment values were recorded for each test.
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high rate mechanical response and sem morphology of ex99 Gun Propellants
2001Co-Authors: Michael G Leadore, Robert J LiebAbstract:Abstract : Two lots of EX99 Gun Propellants from the Naval Surface Warfare Center (NSWC) were tested in uniaxial compression to an end strain of approx. 60%. The materials were preconditioned at test temperatures of 21 deg, 50 deg, and -20 deg C while at ambient pressure. The stress at failure, strain at failure, compressive modulus, failure modulus, incremental energy density (IED), and the fracture assessment values (FAV) were recorded for each test These materials were also evaluated for microstructure using a scanning electron microscope (SEM).
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mechanical response comparison of Gun Propellants evaluated under equivalent time temperature conditions
1993Co-Authors: Robert J Lieb, Michael G LeadoreAbstract:Abstract : Compressive stress relaxation measurements have been performed for single- (M14), double- (JA2), and triple-base (M30) Propellants, as well as a nitramine composite (M43) Gun propellant. This was done to evaluate the response of Gun Propellants at higher rates than can be easily reached within the laboratory by calculating time-temperature shift factors from these relaxation curves. However, in order to apply these shift parameters to high rate events to predict propellant mechanical response and damage, a link must be established between predicted equivalent response and the actual mechanical and failure behavior observed for these Propellants. The mechanical response of these four Propellants was characterized at strain rates, which spanned four orders of magnitude, and at the corresponding shifted temperatures. Test results show that the mechanical response for a given propellant type under each of these temperature-rate conditions was the same in the strain domain for which the relaxation shift factors were measured. In addition, the failure response for a given propellant type also proved to be nearly identical at strain levels outside the domain of the stress relaxation tests. These observations permit greater confidence to be placed in the prediction of mechanical and failure response for Gun Propellants undergoing deformation in strain rate regime the current range of laboratory measurement. Mechanical response, Time-temperature, Propellants, Bed, JA2, M 14, M30, M43, stress Profile, Strain rate.
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time temperature shift factors for Gun Propellants
1993Co-Authors: Robert J Lieb, Michael G LeadoreAbstract:Abstract : To estimate the response of Gun Propellants at higher rates than can be easily reached within the laboratory, stress relaxation measurements have been made in compression for single- (M14), double- (JA2), and triple-based (M30) Propellants, as well as a nitramine composite (M43) Gun propellant, over the temperature range of -40 to 60 degrees celcius. Master curves were generated and shift factors were calculated which were used to determine the time- temperature shift factors for each of the Propellants over these temperatures.
Amarjit Singh - One of the best experts on this subject based on the ideXlab platform.
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closed vessel and thermal studies on triple base Gun Propellants containing cl 20
Journal of Propulsion and Power, 2010Co-Authors: C N Divekar, T K Chakraborthy, R R Sanghavi, U R Nair, A K Sikder, Amarjit SinghAbstract:This study was undertaken to see the effect of the replacement of picrite by 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) (5, 10, and 15%) in triple-base Gun Propellants. Experimental results of a closed-vessel test at a loading density of 0.2 g/cm 3 indicate improvement in energetics of the CL-20-incorporated compositions. The force-constant values obtained were 1046, 1071, and 1095 J/g for 5, 10, and 15% CL-20-based formulations, compared with 1028 J/g for conventional picrite composition as the control. Similar trends were observed for linear burning-rate coefficient β 1 values. The selected energetic plasticizers N-(n-butyl)-N-(2-nitroxyethyl) nitramine (Bu-NENA) and bis-2,2 dinitro propyl formal/acetal (BDNPF/A) were also evaluated for their effectiveness in CL-20-containing Gun-propellant compositions. Thermal analysis was carried out using differential scanning calorimeter and thermogravimetric analyzer. Replacement of picrite by CL-20 resulted in an increase in AH values (by differential scanning calorimeter) compared with that of control composition. Weight-loss data (from thermogravimetric analyzer) showed a similar trend. The CL-20-based compositions were found relatively more sensitive to friction stimuli (12-17 kg) compared with control composition (19.2 kg).
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Feasibility Study of Processing Estane-based LOVA Gun Propellant
Defence Science Journal, 2007Co-Authors: M.a.r. Shaikh, T K Chakraborthy, R R Sanghavi, S. D. Shelar, Amarjit SinghAbstract:Low vulnerability ammunition (LOVA) propellant are currently being developed globally toreplace all types of single-base, double-base and triple-base Gun Propellants, because LOVAPropellants possess advantage like low vulnerability without compromising on ballistic properties.The objective of present study is to establish processing of thermoplastic elastomer (TPE);estane-based LOVA Gun propellant in cord/heptatubular geometry. Keeping in view variousadvantages of TPE such as simple processing, greater dimensional stability, lower productionlosses, superior insensitivity, and mechanical properties of the Propellants, estane 5731(polyurethane-ester-MDI, aromatic polyester) is selected for feasibility study as a binder inLOVA-based Gun propellant composition, processed by solvent and semi-solvent methods andcompared feasibility of processing as well as their evaluation wrt ballistics, vulnerability, andmechanical properties. The results indicate that Gun Propellants processed by semi-solventmethod and extruded at elevated temperatures exhibit better ballistics, mechanical, andvulnerability properties.
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HMX based enhanced energy LOVA Gun propellant.
Journal of Hazardous Materials, 2007Co-Authors: R R Sanghavi, M.a.r. Shaikh, S. D. Shelar, P J Kamale, K Sunil Kumar, Amarjit SinghAbstract:Abstract Efforts to develop Gun Propellants with low vulnerability have recently been focused on enhancing the energy with a further improvement in its sensitivity characteristics. These Propellants not only prevent catastrophic disasters due to unplanned initiation of currently used Gun Propellants (based on nitrate esters) but also realize enhanced energy levels to increase the muzzle velocity of the projectiles. Now, in order to replace nitroglycerine, which is highly sensitive to friction and impact, nitramines meet the requirements as they offer superior energy due to positive heat of formation, typical stoichiometry with higher decomposition temperatures and also owing to negative oxygen balance are less sensitive than stoichiometrically balanced NG. RDX has been widely reported for use in LOVA propellant. In this paper we have made an effort to present the work on scantily reported nitramine HMX based LOVA Gun propellant while incorporating energetic plasticizer glycidyl azide polymer to enhance the energy level. HMX is known to be thermally stable at higher temperature than RDX and also proved to be less vulnerable to small scale shaped charge jet attack as its decomposition temperature is 270 °C. HMX also offers improved impulse due to its superior heat of formation (+17 kcal/mol) as compared to RDX (+14 kcal/mol). It has also been reported that a break point will not appear until 35,000 psi for propellant comprising of 5 μm HMX. Since no work has been reported in open literature regarding replacement of RDX by HMX, the present studies were carried out.
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HMX based enhanced energy LOVA Gun propellant.
Journal of hazardous materials, 2006Co-Authors: R R Sanghavi, M.a.r. Shaikh, S. D. Shelar, P J Kamale, K Sunil Kumar, Amarjit SinghAbstract:Efforts to develop Gun Propellants with low vulnerability have recently been focused on enhancing the energy with a further improvement in its sensitivity characteristics. These Propellants not only prevent catastrophic disasters due to unplanned initiation of currently used Gun Propellants (based on nitrate esters) but also realize enhanced energy levels to increase the muzzle velocity of the projectiles. Now, in order to replace nitroglycerine, which is highly sensitive to friction and impact, nitramines meet the requirements as they offer superior energy due to positive heat of formation, typical stoichiometry with higher decomposition temperatures and also owing to negative oxygen balance are less sensitive than stoichiometrically balanced NG. RDX has been widely reported for use in LOVA propellant. In this paper we have made an effort to present the work on scantily reported nitramine HMX based LOVA Gun propellant while incorporating energetic plasticizer glycidyl azide polymer to enhance the energy level. HMX is known to be thermally stable at higher temperature than RDX and also proved to be less vulnerable to small scale shaped charge jet attack as its decomposition temperature is 270 degrees C. HMX also offers improved impulse due to its superior heat of formation (+17 kcal/mol) as compared to RDX (+14 kcal/mol). It has also been reported that a break point will not appear until 35,000 psi for propellant comprising of 5 microm HMX. Since no work has been reported in open literature regarding replacement of RDX by HMX, the present studies were carried out.
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a study on Gun Propellants based on butyl nena
Energetic Materials, 2004Co-Authors: T K Chakraborthy, K C Raha, B Omprakash, Amarjit SinghAbstract:Researchers have sought to improve performance of Gun Propellants by incorporating various additives in the propellant matrix. Energetic plasticizers were primarily introduced in the formulation to improve the energy content of the propellant with the possible fallout in the form of improvement in the mechanical property. Butyl-NENA is widely reported to play the dual role of better energetics with an improved mechanical property. In the present paper butyl-NENA has been introduced in typical single, double, and triple base propellant formulations. Introduction of butyl-NENA in a single base propellant has resulted in significant improvement in energetics, while in double base and triple base Propellants, it has contributed to enhancing insensitivity and improving mechanical properties.
Rose A Pescerodriguez - One of the best experts on this subject based on the ideXlab platform.
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condensed phase processes during combustion of solid Gun Propellants i nitrate ester Propellants
Combustion and Flame, 2001Co-Authors: Michael A Schroeder, Robert A Fifer, Martin S Miller, Rose A Pescerodriguez, C J S Mcnesby, Gurbax SinghAbstract:Abstract Burning grains of the nitrate ester Gun Propellants M9, M30, and JA2 were extinguished, and the burned surfaces examined microscopically and by infrared (IR) spectroscopy. Studies were carried out at pressures ranging from atmospheric (0.1 MPa to 2.0 MPa). Scanning electron microscopy examination of quenched samples burned at these low pressures indicates that the surface layers affected by combustion are only a few microns in thickness. Examination by photoacoustic Fourier-transform IR spectroscopy and by microreflectance Fourier-transform IR spectroscopy indicates that the main change in the IR spectra of these extinguished surfaces is the presence of a weak carbonyl absorption peak in the region near 1730 cm−1; this is consistent with the idea that a principal initial step is condensed-phase conversion of nitrate ester groupings to aldehyde or ketone groupings through loss of NO2 by N-O cleavage followed by loss of α-hydrogen. In agreement with the scanning electron microscopy results, depth-profiling (carried out by surface-abrasion and by cross-section examination) indicates that in these nitrate ester Propellants only the top few microns have undergone chemical change.
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condensed phase processes during combustion of solid Gun Propellants ii nitramine composite Propellants
Combustion and Flame, 2001Co-Authors: Michael A Schroeder, Robert A Fifer, Martin S Miller, Rose A Pescerodriguez, C J S Mcnesby, Gurbax Singh, J M WidderAbstract:Burning samples of nitramine composite solid Gun Propellants were quenched, and the burned surfaces examined microscopically and by chemical analysis. Studies were carried out on XM39 and M43 Propellants, on an HMX-polyester composition (HMX2) and on pure RDX, at pressures ranging from atmospheric (0.1 MPa to 2.0 MPa). Scanning electron microscopy examination of quenched samples burned at these low pressures indicates that a liquefied layer 100 to 300 μ thick forms during combustion of these nitramine compositions. Bubbles are present, especially at the lower pressures. Gas chromatography mass spectrometry analysis suggests that in the case of XM39, ethyl centralite stabilizer is depleted in the surface layers relative to the plasticizer acetyl triethyl citrate. High-performance liquid chromatography studies indicate that for XM39 (and presumably for M43), HMX2, and RDX, the surface layers exhibit formation of the mechanistically significant nitrosoamines MRDX (also known as ONDNTA) and DRDX. Examination of the burned surfaces of XM39 and of HMX2 by photoacoustic Fourier-transform infrared spectroscopy and by microreflectance Fourier-transform infrared spectroscopy indicates the presence of increased amounts of binder and its decomposition products. Examination of the burned surface of RDX by photoacoustic Fourier-transform infrared indicates the presence of RDX decomposition products. These observations suggest the occurrence of a significant amount of condensed-phase decomposition. Depth profiling, by surface-abrasion and by cross-section examination, indicates that in the nitramine Propellants the molten oxidizer layer is overlain by a layer (∼20 μ thick) of binder and its decomposition products. The roles of vaporization and of thermal decomposition in the liquid layers of the nitramine Propellants are also discussed; it appears that both play significant roles.
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in depth chemistry in plasma exposed m30 and ja2 Gun Propellants
2001Co-Authors: Rose A Pescerodriguez, Richard A Beyer, A Kinkennon, Miguel Del Guercio, Pamela J KasteAbstract:Abstract : JA2 and M30 recovered from interrupted ETC-closed bomb, interrupted ETC small-scale chamber, and open-air experiments were subjected to chemical and microscopic analysis. Evidence of subsurface reaction in both M30 and JA2 has been discovered using a desorption-gas chromatography-mass spectroscopy (D-OC-MS) method to detect low levels of NO in the propellant. It appears that for M30, profiles for radiation-induced denitration of nitrate esters are consistent with Beer's law, and that effects occur as deep as 0.5 mm into the exposed surface. Radiation-induced denitration in JA2 has been detected as deep as 0.75 mm from the exposed surface, but profiles are not consistent with Beer's law. It is suspected that denitration at and below the exposed JA2 surface occurs mostly in locations where large graphite particles are found. Rough estimates of graphite particle temperature when exposed to plasma radiation are in excess of those required for denitration to occur. Microscopic examination of plasma-exposed propellant indicates several features (pits, gouges, blisters, wormholes, etc.) that increase the surface area of the propellant and can contribute to an increased burning rate.
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clean burning low flame temperature solid Gun Propellants
Journal of Energetic Materials, 1996Co-Authors: Rose A Pescerodriguez, Robert A Fifer, Joseph M HeimerlAbstract:Abstract : In an attempt to eliminate nitrogen oxides (NOx's) from the combustion and pyrolysis products of solid Propellants, an investigation into the use of 'De-NOx' agents was performed. The agents selected were all compounds that thermally decompose to generate amines; participation of amines in the thermal De-NOx process results in the reduction of nitrogen oxides to nitrogen. Of all the compounds screened, it was found that urea was the best suited for use as a De-N0x agent in solid Gun Propellants. Use of - resulted in a significant decrease in NOx production. Furthermore, urea is thermally stable up to a temperature of 130 deg C, and is compatible with nitrocellulose-based formulations. Compared to neat JA2 (a double-base propellant), a JA2/urea formulation containing 10 weight-percent urea generates 60% less NOx. Calculations indicate that the incorporation of 4% urea results in a 200 K decrease in flame temperature, and a decrease in impetus and velocity of approximately 4% and 2%, respectively.
Gurbax Singh - One of the best experts on this subject based on the ideXlab platform.
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condensed phase processes during combustion of solid Gun Propellants i nitrate ester Propellants
Combustion and Flame, 2001Co-Authors: Michael A Schroeder, Robert A Fifer, Martin S Miller, Rose A Pescerodriguez, C J S Mcnesby, Gurbax SinghAbstract:Abstract Burning grains of the nitrate ester Gun Propellants M9, M30, and JA2 were extinguished, and the burned surfaces examined microscopically and by infrared (IR) spectroscopy. Studies were carried out at pressures ranging from atmospheric (0.1 MPa to 2.0 MPa). Scanning electron microscopy examination of quenched samples burned at these low pressures indicates that the surface layers affected by combustion are only a few microns in thickness. Examination by photoacoustic Fourier-transform IR spectroscopy and by microreflectance Fourier-transform IR spectroscopy indicates that the main change in the IR spectra of these extinguished surfaces is the presence of a weak carbonyl absorption peak in the region near 1730 cm−1; this is consistent with the idea that a principal initial step is condensed-phase conversion of nitrate ester groupings to aldehyde or ketone groupings through loss of NO2 by N-O cleavage followed by loss of α-hydrogen. In agreement with the scanning electron microscopy results, depth-profiling (carried out by surface-abrasion and by cross-section examination) indicates that in these nitrate ester Propellants only the top few microns have undergone chemical change.
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condensed phase processes during combustion of solid Gun Propellants ii nitramine composite Propellants
Combustion and Flame, 2001Co-Authors: Michael A Schroeder, Robert A Fifer, Martin S Miller, Rose A Pescerodriguez, C J S Mcnesby, Gurbax Singh, J M WidderAbstract:Burning samples of nitramine composite solid Gun Propellants were quenched, and the burned surfaces examined microscopically and by chemical analysis. Studies were carried out on XM39 and M43 Propellants, on an HMX-polyester composition (HMX2) and on pure RDX, at pressures ranging from atmospheric (0.1 MPa to 2.0 MPa). Scanning electron microscopy examination of quenched samples burned at these low pressures indicates that a liquefied layer 100 to 300 μ thick forms during combustion of these nitramine compositions. Bubbles are present, especially at the lower pressures. Gas chromatography mass spectrometry analysis suggests that in the case of XM39, ethyl centralite stabilizer is depleted in the surface layers relative to the plasticizer acetyl triethyl citrate. High-performance liquid chromatography studies indicate that for XM39 (and presumably for M43), HMX2, and RDX, the surface layers exhibit formation of the mechanistically significant nitrosoamines MRDX (also known as ONDNTA) and DRDX. Examination of the burned surfaces of XM39 and of HMX2 by photoacoustic Fourier-transform infrared spectroscopy and by microreflectance Fourier-transform infrared spectroscopy indicates the presence of increased amounts of binder and its decomposition products. Examination of the burned surface of RDX by photoacoustic Fourier-transform infrared indicates the presence of RDX decomposition products. These observations suggest the occurrence of a significant amount of condensed-phase decomposition. Depth profiling, by surface-abrasion and by cross-section examination, indicates that in the nitramine Propellants the molten oxidizer layer is overlain by a layer (∼20 μ thick) of binder and its decomposition products. The roles of vaporization and of thermal decomposition in the liquid layers of the nitramine Propellants are also discussed; it appears that both play significant roles.
Michael A Schroeder - One of the best experts on this subject based on the ideXlab platform.
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condensed phase processes during combustion of solid Gun Propellants i nitrate ester Propellants
Combustion and Flame, 2001Co-Authors: Michael A Schroeder, Robert A Fifer, Martin S Miller, Rose A Pescerodriguez, C J S Mcnesby, Gurbax SinghAbstract:Abstract Burning grains of the nitrate ester Gun Propellants M9, M30, and JA2 were extinguished, and the burned surfaces examined microscopically and by infrared (IR) spectroscopy. Studies were carried out at pressures ranging from atmospheric (0.1 MPa to 2.0 MPa). Scanning electron microscopy examination of quenched samples burned at these low pressures indicates that the surface layers affected by combustion are only a few microns in thickness. Examination by photoacoustic Fourier-transform IR spectroscopy and by microreflectance Fourier-transform IR spectroscopy indicates that the main change in the IR spectra of these extinguished surfaces is the presence of a weak carbonyl absorption peak in the region near 1730 cm−1; this is consistent with the idea that a principal initial step is condensed-phase conversion of nitrate ester groupings to aldehyde or ketone groupings through loss of NO2 by N-O cleavage followed by loss of α-hydrogen. In agreement with the scanning electron microscopy results, depth-profiling (carried out by surface-abrasion and by cross-section examination) indicates that in these nitrate ester Propellants only the top few microns have undergone chemical change.
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condensed phase processes during combustion of solid Gun Propellants ii nitramine composite Propellants
Combustion and Flame, 2001Co-Authors: Michael A Schroeder, Robert A Fifer, Martin S Miller, Rose A Pescerodriguez, C J S Mcnesby, Gurbax Singh, J M WidderAbstract:Burning samples of nitramine composite solid Gun Propellants were quenched, and the burned surfaces examined microscopically and by chemical analysis. Studies were carried out on XM39 and M43 Propellants, on an HMX-polyester composition (HMX2) and on pure RDX, at pressures ranging from atmospheric (0.1 MPa to 2.0 MPa). Scanning electron microscopy examination of quenched samples burned at these low pressures indicates that a liquefied layer 100 to 300 μ thick forms during combustion of these nitramine compositions. Bubbles are present, especially at the lower pressures. Gas chromatography mass spectrometry analysis suggests that in the case of XM39, ethyl centralite stabilizer is depleted in the surface layers relative to the plasticizer acetyl triethyl citrate. High-performance liquid chromatography studies indicate that for XM39 (and presumably for M43), HMX2, and RDX, the surface layers exhibit formation of the mechanistically significant nitrosoamines MRDX (also known as ONDNTA) and DRDX. Examination of the burned surfaces of XM39 and of HMX2 by photoacoustic Fourier-transform infrared spectroscopy and by microreflectance Fourier-transform infrared spectroscopy indicates the presence of increased amounts of binder and its decomposition products. Examination of the burned surface of RDX by photoacoustic Fourier-transform infrared indicates the presence of RDX decomposition products. These observations suggest the occurrence of a significant amount of condensed-phase decomposition. Depth profiling, by surface-abrasion and by cross-section examination, indicates that in the nitramine Propellants the molten oxidizer layer is overlain by a layer (∼20 μ thick) of binder and its decomposition products. The roles of vaporization and of thermal decomposition in the liquid layers of the nitramine Propellants are also discussed; it appears that both play significant roles.