The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Jinn-shing Lee - One of the best experts on this subject based on the ideXlab platform.
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Thermal properties and firing characteristics of the Zr/KClO4/Viton A priming compositions
Thermochimica Acta, 2002Co-Authors: Jinn-shing LeeAbstract:Abstract Zirconium powder is a powerful reducing agent that reacts with oxidizer at elevated temperature, releasing enough heat to ignite pyrotechnic mixtures. In this work, the thermal properties of Zr/KClO4/Viton A priming compositions made by different preparation methods were first investigated using thermal analysis techniques. Then these priming compositions were pressed into the charge holders of pressure cartridges. The firing characteristics of the pressure cartridge were evaluated by using the Bruceton method. The data indicate that the thermal behavior and firing characteristic of Zr/KClO4/Viton A priming compositions were changed because of the different methods of preparation.
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thermal properties and firing characteristics of the zr kclo4 Viton a priming compositions
Thermochimica Acta, 2002Co-Authors: Jinn-shing LeeAbstract:Abstract Zirconium powder is a powerful reducing agent that reacts with oxidizer at elevated temperature, releasing enough heat to ignite pyrotechnic mixtures. In this work, the thermal properties of Zr/KClO4/Viton A priming compositions made by different preparation methods were first investigated using thermal analysis techniques. Then these priming compositions were pressed into the charge holders of pressure cartridges. The firing characteristics of the pressure cartridge were evaluated by using the Bruceton method. The data indicate that the thermal behavior and firing characteristic of Zr/KClO4/Viton A priming compositions were changed because of the different methods of preparation.
Ernst-christian Koch - One of the best experts on this subject based on the ideXlab platform.
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metal fluorocarbon pyrolants xiii high performance infrared decoy flare compositions based on mgb2 and mg2si and polytetrafluoroethylene Viton
Propellants Explosives Pyrotechnics, 2012Co-Authors: Ernst-christian Koch, Arno Hahma, Volker Weiser, Evelin Roth, Sebastian KnappAbstract:In the presented work two experimental pyrolants for use in blackbody infrared decoy flares showing higher performance than baseline magnesium/polytetrafluoroethylene/Viton® (MTV) were investigated. These pyrolants are based on fuels hitherto unknown to pyrotechnics: magnesium diboride, MgB2, and dimagnesium silicide, Mg2Si. Both fuels were formulated with polytetrafluoroethylene, PTFE and a fluorocarbon binder Viton® (designated MbTV and MsTV). MsTV yields higher radiance, Lλ (W cm−2 sr−1) in the mid infrared range (2–5 μm) than MTV at same stoichiometry. The volumetric spectral efficiency Eλ (J cm−3 sr−1) of MbTV is also superior to MTV. MbTV thus allows for size reduction of black body countermeasure flares and thereby has potential to enhance the survivability of aircraft in hostile environments. Due to its very high burning rate MsTV qualifies for first fire and igniter applications.
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Metal‐Fluorocarbon Pyrolants. XIII: High Performance Infrared Decoy Flare Compositions Based on MgB2 and Mg2Si and Polytetrafluoroethylene/Viton®
Propellants Explosives Pyrotechnics, 2012Co-Authors: Ernst-christian Koch, Arno Hahma, Volker Weiser, Evelin Roth, Sebastian KnappAbstract:In the presented work two experimental pyrolants for use in blackbody infrared decoy flares showing higher performance than baseline magnesium/polytetrafluoroethylene/Viton® (MTV) were investigated. These pyrolants are based on fuels hitherto unknown to pyrotechnics: magnesium diboride, MgB2, and dimagnesium silicide, Mg2Si. Both fuels were formulated with polytetrafluoroethylene, PTFE and a fluorocarbon binder Viton® (designated MbTV and MsTV). MsTV yields higher radiance, Lλ (W cm−2 sr−1) in the mid infrared range (2–5 μm) than MTV at same stoichiometry. The volumetric spectral efficiency Eλ (J cm−3 sr−1) of MbTV is also superior to MTV. MbTV thus allows for size reduction of black body countermeasure flares and thereby has potential to enhance the survivability of aircraft in hostile environments. Due to its very high burning rate MsTV qualifies for first fire and igniter applications.
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metal fluorocarbon pyrolants xiv high density high performance decoy flare compositions based on ytterbium polytetrafluoroethylene Viton
Zeitschrift für anorganische und allgemeine Chemie, 2012Co-Authors: Ernst-christian Koch, Arno HahmaAbstract:Three pyrotechnic compositions based on ytterbium /polytetrafluoroethylene/Viton® (YTV) 77/18/5, 82/13/5 and 87/8/5 wt.-% were compared to a baseline magnesium /polytetrafluoroethylene/Viton® (MTV) 60/35/5 wt.-% composition. YTV though energetically inferior to MTV both gravimetrically and volumetrically exhibit a radiance Lλ (W·sr–1·cm–2) superior to MTV in the important beta-band (λ = 3.5–4.6 μm). This is assumed to be due to the selective emissivity of Yb2O3 which is formed in the afterburning zone of YTV. The emissivity of Yb2O3 is 7–10 times higher than that of MgO in the same spectral range. Due to the high density of ytterbium and the formulations based thereon YTV are promising candidates for autophagous nose cones for kinematic blackbody flares.
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Metal‐Fluorocarbon Pyrolants. XIV: High Density‐High Performance Decoy Flare Compositions Based on Ytterbium/Polytetrafluoroethylene/Viton®
Zeitschrift für anorganische und allgemeine Chemie, 2012Co-Authors: Ernst-christian Koch, Arno HahmaAbstract:Three pyrotechnic compositions based on ytterbium /polytetrafluoroethylene/Viton® (YTV) 77/18/5, 82/13/5 and 87/8/5 wt.-% were compared to a baseline magnesium /polytetrafluoroethylene/Viton® (MTV) 60/35/5 wt.-% composition. YTV though energetically inferior to MTV both gravimetrically and volumetrically exhibit a radiance Lλ (W·sr–1·cm–2) superior to MTV in the important beta-band (λ = 3.5–4.6 μm). This is assumed to be due to the selective emissivity of Yb2O3 which is formed in the afterburning zone of YTV. The emissivity of Yb2O3 is 7–10 times higher than that of MgO in the same spectral range. Due to the high density of ytterbium and the formulations based thereon YTV are promising candidates for autophagous nose cones for kinematic blackbody flares.
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metal fluorocarbon pyrolants iii development and application of magnesium teflon Viton mtv
Propellants Explosives Pyrotechnics, 2002Co-Authors: Ernst-christian KochAbstract:The development and application of pyrotechnic payloads based on magnesium, Teflon® and Viton®, so-called MTV is reviewed. MTV is applied in decoy flares, tracking flares, countermeasure torches, base bleed units, tracer units, igniters, solid rocket propellants, RAM propellants, incendiary devices and signaling applications.
Chenguang Zhu - One of the best experts on this subject based on the ideXlab platform.
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Experimental and numerical analyses of the combustion characteristics of Mg/PTFE/Viton fuel-rich pyrolants in the atmospheric environment
Numerical Heat Transfer Part A-applications, 2020Co-Authors: Kangkang Zhang, Yuge Han, Dengfeng Ren, Chenguang ZhuAbstract:Magnesium/polytetrafluoroethylene/Viton (MTV) fuel-rich pyrolants use the atmospheric oxygen as a complementary oxidizer to sustain and alter the performance of the combustion reaction. The flame d...
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experimental and numerical analyses of the combustion characteristics of mg ptfe Viton fuel rich pyrolants in the atmospheric environment
Numerical Heat Transfer Part A-applications, 2020Co-Authors: Kangkang Zhang, Yuge Han, Dengfeng Ren, Chenguang ZhuAbstract:Magnesium/polytetrafluoroethylene/Viton (MTV) fuel-rich pyrolants use the atmospheric oxygen as a complementary oxidizer to sustain and alter the performance of the combustion reaction. The flame d...
Satyendra Mishra - One of the best experts on this subject based on the ideXlab platform.
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Property investigation of surface-modified MMT on mechanical and photo-oxidative degradation of Viton rubber composites
Polymer Bulletin, 2016Co-Authors: Navinchandra G. Shimpi, Ananda D. Mali, Satyendra MishraAbstract:At different time intervals, photo-oxidative degradation of organically modified montmorillonite (OMMT):Viton rubber composites were studied under accelerated UV (≥290 nm) irradiation. The changes in properties (mechanical, thermal, and physical) before and after UV exposure were studied using universal testing machine (UTM), thermogravimetric analyzer (TGA) and shore A hardness tester. Meanwhile, surface of montmorillonite (MMT) was modified using column chromatography technique (quaternary long chain ammonium salt as an intercalent), which resulted in uniform exchange of ions between MMT and ion exchange resin; and thus d -spacing increases to 31.5 Å. Viton:OMMT nanocomposites were prepared using two roll mill and compression molding machine to obtain a square sheet. Prolonged exposure to UV leads a progressive decrease in mechanical, thermal and physical properties along with the change in behavior of filler–matrix interaction, which was due to decrease in cross-linkage density with increase in the mobility of rubber chains. The increases in carbonyl (>CO), hydroxyl (–OH) functional groups after degradation of OMMT:Viton rubber composites at different time intervals (0, 100, 200, 300 h of UV exposure) were studied using Fourier transform infrared spectroscopy (FTIR). Besides this, the change in surface behavior of Viton rubber composites before and after degradation was studied using scanning electron microscopy (SEM). Overall, the study shows that the OMMT:Viton composites were affected more upon irradiation compared to pristine Viton composites and it was more prominent at 12 wt% loading of 300 h of UV exposure.
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thermal mechanical and morphological properties of surface modified montmorillonite reinforced Viton rubber nanocomposites
Polymer International, 2014Co-Authors: Ananda D. Mali, Navinchandra G. Shimpi, Satyendra MishraAbstract:Thermal, mechanical and morphological properties of surface-modified montmorillonite (OMMT)-reinforced Viton rubber nanocomposites were studied. The surface of montmorillonite was modified with a column chromatography technique using quaternary long-chain ammonium salt as an intercalant, which resulted in uniform exchange of ions between montmorillonite and the ion-exchange resin, and increased the d-spacing to 31.5 A. This improved d-spacing was due to the use of an ion-exchange column of sufficient length (35 cm) and diameter (5 cm) with maximum retention time for exchange of ions. The Viton nanocomposites reinforced with OMMT (3–12 wt%) were prepared using a two-roll mill and moulded in a compression moulding machine. Tensile strength increased 3.17 times and elongation at break from 500 to 600% for 9 wt% loading of OMMT in comparison to pristine Viton rubber. Thermogravimetric analysis revealed that the presence of OMMT greatly improved the thermal stability. This improvement in properties with increasing OMMT loading was due to insertion of rubber chains between the OMMT plates with good wetting ability. Overall, at an optimum OMMT loading of 9 wt%, the properties of the Viton rubber nanocomposites improved, and subsequently worsened at 12 wt% due to agglomeration of OMMT as revealed by scanning electron microscopy and atomic force microscopy images. © 2013 Society of Chemical Industry
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Thermal, mechanical and morphological properties of surface‐modified montmorillonite‐reinforced Viton rubber nanocomposites
Polymer International, 2013Co-Authors: Ananda D. Mali, Navinchandra G. Shimpi, Satyendra MishraAbstract:Thermal, mechanical and morphological properties of surface-modified montmorillonite (OMMT)-reinforced Viton rubber nanocomposites were studied. The surface of montmorillonite was modified with a column chromatography technique using quaternary long-chain ammonium salt as an intercalant, which resulted in uniform exchange of ions between montmorillonite and the ion-exchange resin, and increased the d-spacing to 31.5 A. This improved d-spacing was due to the use of an ion-exchange column of sufficient length (35 cm) and diameter (5 cm) with maximum retention time for exchange of ions. The Viton nanocomposites reinforced with OMMT (3–12 wt%) were prepared using a two-roll mill and moulded in a compression moulding machine. Tensile strength increased 3.17 times and elongation at break from 500 to 600% for 9 wt% loading of OMMT in comparison to pristine Viton rubber. Thermogravimetric analysis revealed that the presence of OMMT greatly improved the thermal stability. This improvement in properties with increasing OMMT loading was due to insertion of rubber chains between the OMMT plates with good wetting ability. Overall, at an optimum OMMT loading of 9 wt%, the properties of the Viton rubber nanocomposites improved, and subsequently worsened at 12 wt% due to agglomeration of OMMT as revealed by scanning electron microscopy and atomic force microscopy images. © 2013 Society of Chemical Industry
Timothy J. Foley - One of the best experts on this subject based on the ideXlab platform.
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combustion of silicon teflon Viton and aluminum teflon Viton energetic composites
Journal of Propulsion and Power, 2010Co-Authors: Christina D. Yarrington, Steven F. Son, Timothy J. FoleyAbstract:DOI: 10.2514/1.46182 The combustion of Si- and Al-based systems using polytetrafluoroethylene (PTFE) as the oxidizer and Fluorel FC 2175 (a copolymer of hexafluoropropylene and vinylidene fluoride) as a binder has been studied. Experimental data were obtained using two methods: 1) instrumented tube burns and 2) pressed pellets inside a windowed pressure vessel. Loose-powder burning rates were seen to optimize at slightly-fuel-rich mixture ratios for Si/PTFE/FC-2175 (SiTV). Al/PTFE/FC-2175 (AlTV) burning rates optimized near a stoichiometric ratio. Pressures calculated by assuming constant-volume combustion equilibrium were seen to match experimental values from burn-tube experiments when burning rates were at or near peak values. The pressure dependence of SiTV and AlTV pellet burning rates was also characterized and compared with reported Mg/PTFE/Viton (MTV) results. SiTV showed power-law dependence with a constant-pressure exponent over the experimental range of pressures. AlTV was showntoexhibitnonconstant-pressureexponentbehavior.SiTVburningratesoptimizedatmixtureratiossimilarto that of the tube burns. AlTV burning rates increased well past a stoichiometric ratio and decreased at a fuel-rich ratio, which is a similar trend to MTV burning rates.
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Combustion of Silicon/Teflon/Viton and Aluminum/Teflon/Viton Energetic Composites
Journal of Propulsion and Power, 2010Co-Authors: Christina D. Yarrington, Steven F. Son, Timothy J. FoleyAbstract:The combustion of Si- and Al-based systems using polytetrafluoroethylene (PTFE) as the oxidizer and Fluorel FC 2175 (a copolymer of hexafluoropropylene and vinylidene fluoride) as a binder has been studied. Experimental data were obtained using two methods: 1) instrumented tube burns and 2) pressed pellets inside a windowed pressure vessel. Loose-powder burning rates were seen to optimize at slightly-fuel-rich mixture ratios for Si/PTFE/FC-2175 (SiTv). Al/PTFE/FC-2175 (AlTV) burning rates optimized near a stoichiometric ratio. Pressures calculated by assuming constant-volume combustion equilibrium were seen to match experimental values from burn-tube experiments when burning rates were at or near peak values. The pressure dependence of SiTV and AlTV pellet burning rates was also characterized and compared with reported Mg/PTFE/Viton (MTV) results. SiTV showed power-law dependence with a constant-pressure exponent over the experimental range of pressures. AlTV was shown to exhibit nonconstant-pressure exponent behavior. SiTV burning rates optimized at mixture ratios similar to that of the tube burns. AlTV burning rates increased well past a stoichiometric ratio and decreased at a fuel-rich ratio, which is a similar trend to MTV burning rates.
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Combustion Properties of Silicon/Teflon/Viton and Aluminum/Teflon/Viton Composites
47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition, 2009Co-Authors: Christina D. Yarrington, Steven F. Son, Brad Lothamer, Timothy J. FoleyAbstract:The combustion of aluminum-based nano energetic materials has received much attention in recent years. Silicon-based nano composites have not been studied so extensively, even though the predicted thermochemistry properties show promise and silicon reactives may have other advantages. Also, almost no attention has been given to silicon reactives using fluorinated oxidizers. A more complete body of experimental knowledge with respect to the combustion of nano silicon-based reactives with fluorinated oxidizers is needed to better understand the mechanisms of combustion, as well as to develop the possible applications. Combustion equilibrium calculations were performed on silicon and aluminum-based systems using polytetrafluoroethylene (PTFE or Teflon) as the oxidizer. It was found that silicon and aluminum with fluorinated oxidizers have similar predicted equilibrium temperatures. Basic combustion properties were obtained using stoichiometries chosen based on the thermochemical equilibrium calculations for both aluminum and silicon. A range of stoichiometries were also tested for the silicon systems. Fluorel FC 2175 binder (chemically equivalent to Viton R ©) was added to prevent sample brittleness and allow for the characterization of burning rate of pressed pellets at various pressures. Instrumented tube burns were also performed in order to determine the loose powder burning rate. Silicon reactive loose powder burning rates were found to optimize at slightly fuel rich stoichiometries, similar to aluminum-based reactives. It was found that there exists different combustion modes for aluminum reactives in tube burns. Depending on ignition method, either a fast burning steady state burn would occur, or a slow burn which transitioned to the other mode at a later time. A strong link to pressure is likely key to the presence of these two combustion modes and the transition between them. Aluminum reactive peak pressures and burning rates were 9,000 PSI and 1,070 m/s, and silicon reactive peak pressure and average burning rate were 7660 PSI and 424 m/s. Reactive silicon pellets were also found to optimize at fuel-rich compositions and the burning rates were found to follow a power law dependence on pressure, however, this dependence (characterized by the power law exponent) was not significantly affected by stoichiometry, in contrast to magnesium/Teflon/Viton (MTV) systems. Aluminum reactive pressed pellet burning rates were better fit by a second order polynomial. A comparison between silicon and aluminum-based reactive pellets show comparable burning rates for mixture ratios chosen at the calculated maximum temperature. Also, the burning rate did not increase continuously with added wt% fuel in the mixture as MTV systems are reported to do, but reached a peak and then declined, indicating more of a temperature dependence.
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combustion properties of silicon teflon Viton and aluminum teflon Viton composites
47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition, 2009Co-Authors: Christina D. Yarrington, Steven F. Son, Brad Lothamer, Timothy J. FoleyAbstract:The combustion of aluminum-based nano energetic materials has received much attention in recent years. Silicon-based nano composites have not been studied so extensively, even though the predicted thermochemistry properties show promise and silicon reactives may have other advantages. Also, almost no attention has been given to silicon reactives using fluorinated oxidizers. A more complete body of experimental knowledge with respect to the combustion of nano silicon-based reactives with fluorinated oxidizers is needed to better understand the mechanisms of combustion, as well as to develop the possible applications. Combustion equilibrium calculations were performed on silicon and aluminum-based systems using polytetrafluoroethylene (PTFE or Teflon) as the oxidizer. It was found that silicon and aluminum with fluorinated oxidizers have similar predicted equilibrium temperatures. Basic combustion properties were obtained using stoichiometries chosen based on the thermochemical equilibrium calculations for both aluminum and silicon. A range of stoichiometries were also tested for the silicon systems. Fluorel FC 2175 binder (chemically equivalent to Viton R ©) was added to prevent sample brittleness and allow for the characterization of burning rate of pressed pellets at various pressures. Instrumented tube burns were also performed in order to determine the loose powder burning rate. Silicon reactive loose powder burning rates were found to optimize at slightly fuel rich stoichiometries, similar to aluminum-based reactives. It was found that there exists different combustion modes for aluminum reactives in tube burns. Depending on ignition method, either a fast burning steady state burn would occur, or a slow burn which transitioned to the other mode at a later time. A strong link to pressure is likely key to the presence of these two combustion modes and the transition between them. Aluminum reactive peak pressures and burning rates were 9,000 PSI and 1,070 m/s, and silicon reactive peak pressure and average burning rate were 7660 PSI and 424 m/s. Reactive silicon pellets were also found to optimize at fuel-rich compositions and the burning rates were found to follow a power law dependence on pressure, however, this dependence (characterized by the power law exponent) was not significantly affected by stoichiometry, in contrast to magnesium/Teflon/Viton (MTV) systems. Aluminum reactive pressed pellet burning rates were better fit by a second order polynomial. A comparison between silicon and aluminum-based reactive pellets show comparable burning rates for mixture ratios chosen at the calculated maximum temperature. Also, the burning rate did not increase continuously with added wt% fuel in the mixture as MTV systems are reported to do, but reached a peak and then declined, indicating more of a temperature dependence.
