The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Hugh A Bruck - One of the best experts on this subject based on the ideXlab platform.
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development and characterization of high performance solid Propellants containing nano sized energetic ingredients
31st International Symposium on Combustion, 2007Co-Authors: J R Luman, B Wehrman, N M Masoud, T G Manning, L. E. Harris, Richard A Yetter, Hugh A BruckAbstract:Abstract This paper addresses the development of a pair of layered solid Propellants suitable for use in a fast-core gun-Propellant charge application. A baseline Propellant combination was formulated using RDX particles and thermoplastic-elastomer binder as the major ingredients and CL-20 and nitroguanadine as separate additives for high- and low-energy Propellants. The Propellant’s burning rate was characterized and insufficient burning-rate ratio between the fast and slow baseline Propellants was found. Impetus obtained from the combustion of the combined baseline Propellants was also found to be far from the demanded value of 1300 J/g. Several modifications were made by introducing nano-sized aluminum particles and ultra-fine boron particles as well as high-energy oxidizer HNF into the Propellant formulation. It was found that the addition of nano-sized aluminum particles can enhance the Propellant burning rate only when the Propellant contains oxidizers with a positive oxygen balance. Without the presence of positive oxygen balance oxidizer, the exothermic reaction of aluminum and boron particles occurs at a large distance from the burning surface introducing an energy-sink effect. The results obtained from the combustion of the advanced Propellants show that an average impetus of 1299 J/g, a flame temperature of 3380 K with a burn rate ratio around 3 between the fast- and the slow-burning layers can be achieved. These conditions are desired for fast-core layered Propellant applications. The impact sensitivities of the baseline, intermediate and advanced Propellants were measured. The results show that addition of HNF and nano-sized aluminum exhibited improved impact sensitivity at levels that can be considered acceptable for deployment.
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effects of nano sized energetic ingredients in high performance solid gun Propellants
2006Co-Authors: T G Manning, B Wehrman, N M Masoud, Richard A Yetter, D P Thompson, R Luman, Hugh A BruckAbstract:Abstract : Unique Propellant configurations, such as fast-core designs, require a layered Propellant with tailored burn rate. The use of these layered Propellants is expected to improve the energy management during the ballistic cycle and hence increase the muzzle velocity. These new Propellants under development have different thermochemistry from that of traditional nitrocellulose-based Propellants. The layered Propellant is typically stacked as laminated disks in the cartridge chamber. Layered Propellants (also called fast-core Propellants) consist of an inner layer of fast burning high-impetus Propellant imbedded in two layers of slower burning low-impetus Propellant. Propellant geometries are tightly controlled such that the fast burning inner-core layer does not start burning until the volume available has slightly increased due to the projectile motion. This allows the pressure to be maintained at a high level for a relatively long duration. Advances in energetic materials have been made in all types of composite Propellant ingredients, including binders, oxidizers, and metal additives. Special processing techniques of functionally graded energetic materials have also been developed in recent years. The goal of this study is to develop a pair of layered Propellants through a "materials-by-design" approach for use in a fast-core gun propulsion application. A pair of baseline Propellants was initially developed and named as ME (moderate energy) Propellant with a relatively slow burning rate and HE (high-energy) Propellant with a fast burning rate. Modifications of these Propellants with different ingredients have been made such that the burning rate ratio between fast and slow burning Propellants is suitable for use in applications requiring layered Propellants (~ 3:1).
Makoto Kohga - One of the best experts on this subject based on the ideXlab platform.
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Burning Characteristics of AP/HTPB Propellants Supplemented with Low Thermal Conductivity Powders
51st AIAA SAE ASEE Joint Propulsion Conference, 2015Co-Authors: Makoto Kohga, Shingo ShioyaAbstract:Thermal conduction in solid Propellants is a dominant process of solid Propellant combustion and influences the burning characteristics of the Propellants. Fine, high thermal conductivity materials do not affect the burning characteristics of Propellants, while low thermal conductivity materials improve them. This study is part of a series of studies on the influence of variations in solid-phase thermal conduction on the burning characteristics of Propellants. ZrO2, steatite, and SiO2 were used as low thermal conductivity materials. These additives increased the burning rate by the hot spot effect. In addition, the influence of these additives on the burning rate was dependent on the ammonium perchlorate particle size. For the Propellant with coarse ammonium perchlorate particles, the enhancement in the burning rate was dependent on the particle size or the specific surface area of the additives.
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thermal decomposition behaviors and burning characteristics of an nitramine based composite Propellant
Journal of Energetic Materials, 2015Co-Authors: Tomoki Naya, Makoto KohgaAbstract:Ammonium nitrate (AN) has attracted much attention due to its clean burning nature as an oxidizer. However, an AN-based composite Propellant has the disadvantages of low burning rate and poor ignitability. In this study, we added nitramine of cyclotrimethylene trinitramine (RDX) or cyclotetramethylene tetranitramine (HMX) as a high-energy material to AN Propellants to overcome these disadvantages. The thermal decomposition and burning rate characteristics of the prepared Propellants were examined as the ratio of AN and nitramine was varied. In the thermal decomposition process, AN/RDX Propellants showed unique mass loss peaks in the lower temperature range that were not observed for AN or RDX Propellants alone. AN and RDX decomposed continuously as an almost single oxidizer in the AN/RDX Propellant. In contrast, AN/HMX Propellants exhibited thermal decomposition characteristics similar to those of AN and HMX, which decomposed almost separately in the thermal decomposition of the AN/HMX Propellant. The ign...
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thermal decomposition behaviors and burning characteristics of ammonium nitrate polytetrahydrofuran glycerin composite Propellant
Combustion and Flame, 2011Co-Authors: Makoto Kohga, Kayoko OkamotoAbstract:Ammonium nitrate (AN)-based Propellant is plagued by several drawbacks: low burning rate, poor ignitability, and low energy. The application of an energetic binder is an effective approach to the practical use of AN-based Propellants but has not been used to date because the synthesis processes are complicated and expensive. Polytetrahydrofuran (PTHF) is a raw material for rubber products and is not an energetic material. The repeating unit of PTHF has one oxygen atom, and although PTHF could not become solid with use of a curing agent alone, PTHF became rubbery with the use of glycerin as a crosslinking modifier. Thus the PTHF/glycerin mixture would be a useful binder to improve the burning characteristics of AN-based Propellants, due to the oxygen atoms in the mixture. The use of PTHF/glycerin binder is theoretically effective for enhancing the performance of AN-based Propellant, but the combined AN/PTHF/glycerin Propellants failed to ignite; they only generated a flashing flame at the ignition event. The ignition failure of the AN/PTHF/glycerin Propellant occurred because the melted binder covered the burning surface and interfered with the evolution of the AN decomposition gases and the heat flux feedback from the flame to AN. The AN/PTHF/glycerin Propellant was then burned with the addition of a catalyst, and the effect of PTHF/glycerin binder on the improvement of burning characteristics was apparent. The PTHF/glycerin binder was an effective binder material for improving a performance of the AN-based composite Propellant.
P A Ramakrishna - One of the best experts on this subject based on the ideXlab platform.
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an effective method to embed catalyst on ap and its effect on the burn rates of aluminized composite solid Propellants
Combustion and Flame, 2017Co-Authors: Gaurav Marothiya, Chaitanya Vijay, Kumar Ishitha, P A RamakrishnaAbstract:Abstract This study makes an attempt to demonstrate the feasibility of a technique to embed the catalyst on ammonium perchlorate (AP) surface, in aluminized composite solid Propellants. Micron sized iron oxide (IO) and nano sized IO were used in this study and its effect on the viscosity and burn rates of composite solid Propellants were recorded. Burn rates of Propellants prepared with this catalyst embedded AP were measured using a Crawford bomb and observed to be increasing using this technique due to the proximity of the catalyst with AP. The increase in burn rate obtained with micron sized and nano sized catalyst embedded on AP were 27.4% and 7.3%, respectively over those mechanically mixed in the Propellant. The end of mix viscosity of the Propellant prepared with nano IO was observed to be highest (4.27 × 103 Poise) when it is mechanically mixed in the Propellant. The viscosity of the Propellant was observed to improve to 3.79 × 103 Poise with the use of the technique of embedding the nano catalyst on AP as the total number of particles reduced. These explanations were the result of a computational model of randomly packed particles of AP, aluminum and catalyst generated for a Propellant with 1% catalyst.
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studies on the role of iron oxide and copper chromite in solid Propellant combustion
Combustion and Flame, 2014Co-Authors: Kumar Ishitha, P A RamakrishnaAbstract:Abstract Iron oxide and copper chromite are the known burn rate enhancers used in a composite solid Propellant. Lot of research has been carried out to understand the mechanism or location of action of the burn rate modifiers so as to better tailor the burning rate of a composite Propellant. The literature is still very confusing in affirming the mechanism. Here, a systematic study has been carried out, by undertaking experiments at varying levels of combinations of the individual components (ammonium perchlorate, which is oxidizer and hydroxyl terminated poly butadiene, which is both fuel and binder) of composite solid Propellant. Firstly, thermal gravimetric analysis, differential scanning calorimetry and burning rate measurements on the individual components are carried out to study the effect of iron oxide and copper chromite on the components themselves. It has been noticed that though both iron oxide and copper chromite are effective on ammonium perchlorate, iron oxide is slightly more effective than copper chromite. Also, copper chromite enhanced the binder melt flow, while iron oxide reduced it. These are followed-up by experiments on sandwich Propellants, which give greater insight and enables better understanding of the behavior of iron oxide and copper chromite in composite Propellants, as these are simple two-dimensional analogue of the composite solid Propellants. Finally, experiments are carried out on the composite solid Propellants to obtain a holistic understanding of the behavior/location of action of iron oxide and copper chromite in them. These studies are used to explain certain unexplained but observed phenomena, at the same time elucidating the location of action of these burn rate modifiers in composite solid Propellant combustion. Based on these observations, it has been proposed that both iron oxide and copper chromite are primarily acting on the condensed phase. These studies are further complimented with experiments to analyze the thermal conductivity measurements of various Propellant samples. This is pursued to understand the reason for the differences in burn rate pressure index for the composite Propellants with iron oxide and with copper chromite. It has been understood from these studies that the thermal conductivity of a composite Propellant is a key parameter, which affects the burn rate pressure index. Literature has never addressed it from this perspective.
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Development of AP/HTPB based Fuel-rich Propellant for Solid Propellant Ramjet
49th AIAA ASME SAE ASEE Joint Propulsion Conference, 2013Co-Authors: Jogesh K. Nanda, P A RamakrishnaAbstract:It is well known that reduction of Ammonium Perchlorate (AP) content in composite Propellant reduces the burn rate of solid composite Propellants. Below a certain level of AP content the Propellant does not burn. This paper explores ways to enhance the burn rate of fuel-rich composite solid Propellant. The methods employed to enhance the burn rate of the Propellant in the study are 1) Use of pyral 2) Recrystallization of AP, 3) Method to add catalyst into the Propellant and 4) Addition of AC with moisture. Pyral was added as a metal fuel which resulted in Propellants having higher burn rates and their density variations along the length were absent contrary to those without pyral. Addition of AC with moisture in these Propellants increases the burn rate pressure index. The highest burn rate achieved is 3.8 mm/s at 70 bar with the Propellant comprised of AP (particle size < 15 μm) and nanosized catalyst.
Kayoko Okamoto - One of the best experts on this subject based on the ideXlab platform.
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thermal decomposition behaviors and burning characteristics of ammonium nitrate polytetrahydrofuran glycerin composite Propellant
Combustion and Flame, 2011Co-Authors: Makoto Kohga, Kayoko OkamotoAbstract:Ammonium nitrate (AN)-based Propellant is plagued by several drawbacks: low burning rate, poor ignitability, and low energy. The application of an energetic binder is an effective approach to the practical use of AN-based Propellants but has not been used to date because the synthesis processes are complicated and expensive. Polytetrahydrofuran (PTHF) is a raw material for rubber products and is not an energetic material. The repeating unit of PTHF has one oxygen atom, and although PTHF could not become solid with use of a curing agent alone, PTHF became rubbery with the use of glycerin as a crosslinking modifier. Thus the PTHF/glycerin mixture would be a useful binder to improve the burning characteristics of AN-based Propellants, due to the oxygen atoms in the mixture. The use of PTHF/glycerin binder is theoretically effective for enhancing the performance of AN-based Propellant, but the combined AN/PTHF/glycerin Propellants failed to ignite; they only generated a flashing flame at the ignition event. The ignition failure of the AN/PTHF/glycerin Propellant occurred because the melted binder covered the burning surface and interfered with the evolution of the AN decomposition gases and the heat flux feedback from the flame to AN. The AN/PTHF/glycerin Propellant was then burned with the addition of a catalyst, and the effect of PTHF/glycerin binder on the improvement of burning characteristics was apparent. The PTHF/glycerin binder was an effective binder material for improving a performance of the AN-based composite Propellant.
Charles Dubois - One of the best experts on this subject based on the ideXlab platform.
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stability and performance of gun Propellants incorporating 3 6 dihydrazino s tetrazine and 5 aminotetrazolium nitrate
Journal of Hazardous Materials, 2019Co-Authors: Jonathan Lavoie, Catalin Florin Petre, Simon Durand, Charles DuboisAbstract:The addition of either 3,6-dihydrazino-s-tetrazine (DHT) or 5-aminotetrazolium nitrate (HAT-NO3) to nitrocellulose-based Propellants were investigated. At 25% (m/m) concentration, DHT and HAT-NO3 had significant impact on the burning rate of the Propellant, up to 80% higher than that of the reference Propellant. DHT was found to have very poor compatibility with nitrocellulose and the nitrated esters used in the formulation despite the presence of stabilizer. This lead to a rapid autocatalytic decomposition reaction resulting in a deflagration. HAT-NO3 also had poor compatibility with the same materials. On the contrary, non-ionic tetrazoles were found to be fully compatible with nitrocellulose and nitrated esters based Propellants. Most nitrogen-rich energetic molecules have been studied for their explosive characteristics. This study shed light on the potential use of these materials as burning rate modifiers for gun Propellant applications, for which very little is known. Moreover, it investigates the stability of the formulations incorporating nitrogen-rich molecules, as a means of assessing the safe use of these novel Propellants.
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burning rates and thermal behavior of bistetrazole containing gun Propellants
Propellants Explosives Pyrotechnics, 2017Co-Authors: Jonathan Lavoie, Pierreyves Paradis, Catalin Florin Petre, Charles DuboisAbstract:The influence of two selected bistetrazoles, 5,5′-bis(1H-tetrazolyl)-amine (BTA) and 5,5′-hydrazinebistetrazole (HBT), on the combustion behavior of a typical triple-base Propellant was investigated. Seven Propellant formulations, one reference and six others incorporating 5 %, 15 %, and 25 % of either HBT or BTA compounds, respectively, were mixed and extruded into a cylindrical, no perforations, geometry. The resulting Propellants showed high burning rates, up to 93 % higher than the reference formulation at 100 MPa. However, the increase in burning rates came at the cost of higher burning rate dependency on pressure, with a pressure exponent as high as 1.4 for certain formulations. HBT-containing Propellants showed notably lower flame temperature when compared to the reference formulation, with a flame temperature reduction of up to 461 K for the Propellant containing 25 % HBT. The thermal behavior of the Propellants was also investigated through DSC experiments. The addition of bistetrazoles provided lower decomposition temperatures than the pure nitrogen-rich materials, indicating that the two compounds probably react readily with the −ONO2 groups present in the nitrocellulose and the plasticizers used in the formulation. The onset temperature of all Propellants remained within acceptable ranges despite the observed decrease caused by the addition of the bistetrazole compounds.
