Production and Characterization of Nano-Aluminum and its Effect in Solid Propellant Combustion
08 Jan 2007-Vol. 24, pp 16887-16895
TL;DR: In this article, the authors measured the size and shape of nano-aluminum particles using a transmission electron microscope (TEM) and X-ray diffraction (XRD) results also confirmed that the powder formed by the electrical wire explosion method as aluminum with an average size of 42 nm.
Abstract: Nano-aluminum particles were produced by the electrical wire explosion method at this laboratory. The size and shape of the particles were measured using a transmission electron microscope (TEM). Aluminum wires are exploded by application of high voltage, to yield particles of size around 40 nm. The X-ray diffraction (XRD) results also confirm that the powder formed by the above process as aluminum with an average size of 42 nm. Previous studies on ultrafine-aluminum applied to solid propellants have tested a particle size not less than about 100 nm. The thermal characteristics were analyzed using thermo gravimetric and differential thermal analyses (TG-DTA). The composition of the material was characterized by energy dispersive angle X-ray (EDAX) analysis. The low pressure deflagration limit (LPDL) tests were carried out for dry-pressed pellets of the nanoaluminum or normal aluminum with ammonium perchlorate (AP). Sandwich burning tests of the nano-aluminum and normal aluminum added to the middle lamina of binder were also carried out. It showed that the addition of nano-aluminum marginally increased the burning rate at elevated pressures and higher lamina thicknesses. Composite propellant formulations were developed out with a bimodal size distribution of AP particles, with the baseline non-aluminized formulations exhibiting plateau burning rate trends. Burning rate studies of the non-aluminized, nano-aluminized, and normal aluminized propellants were carried out. It was found that the burning rate of the nano-aluminized propellants increased by 100% compared to normal aluminized propellants. In the nano-aluminized propellants, the plateau effects in the burning rate of the corresponding non-aluminized propellants in the intermediate pressure range were removed, but significantly low pressure-exponents were observed at elevated pressures. The results point out that the nearly complete combustion of nano-aluminum near the propellant burning surface actually controls the propellant burning rate. The nano-aluminum combustion is diffusion-limited at elevated pressures, and hence, results in significantly low pressure-exponents of burning rate in that pressure range.
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TL;DR: In this article, the use of micron-sized aluminum (pyral, average particle size 3.66 µm) with a higher specific surface area was proposed as a good candidate to enhance the burn rate of the composite propellant.
Abstract: This paper proposes the use of micron-sized aluminum (pyral, average particle size 3.66 μm) with a higher specific surface area as a good candidate to enhance the burn rate of the composite propellant. Experiments were performed in the pressure range of 10 to 70 bar in a window bomb for measuring the burn rate. Comparison of these burn rate results with those obtained using micron- and nanosized aluminum found that the performance of pyral was in between that of micron- and nanosized aluminum. The reason for the high burn rates observed with pyral is due to the flake like appearance of pyral with a large specific surface area. It is argued that, if the specific surface area is large, then the thickness becomes the characteristic length scale. This ensures the heat release from the aluminum combustion to occur closer to the propellant surface as the thickness of pyral is in nanometers. Both the x-ray diffraction and heat of formation analyses indicated that pyral had higher purity than nanoaluminum, which...
24 citations
13 Dec 2019
TL;DR: The chemically prepared nZVAl was characterized using UV-Vis spectrum, X-ray diffraction (XRD), and sca... as discussed by the authors, and proved high reactivity to adsorb and degrade various contaminants removal.
Abstract: Zero-valent metals proved high reactivity to adsorb and degrade various contaminants removal. The chemically prepared nZVAl was characterized using UV-Vis spectrum, X-ray diffraction (XRD), and sca...
19 citations
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01 Jan 2019
TL;DR: Bhattacharya et al. as discussed by the authors discussed some of the detailed and novel synthesis, fabrication, characterization, tunability, storage and application aspects of nano-energetic materials.
Abstract: With the advent of microand nano-scale devices, the energy management at molecular level is vital for performance enhancement. The field of nano-energetics focuses on the study of synthesis and fabrication of energetic materials or composites at nano-level. The nano-energetic materials may include almost all materials associated with the generation and storage of energy in all forms, viz., thermal, electrical, chemical, etc. The advantages of nano-scale are many which include characteristics like overall small particle size, large specific surface area, high surface energy and strong surface activity, and all these properties associated with the nano-scale provide a key to obtain an overall high energy turnover from such materials and composites and provide solutions to some very pressing current technology needs. The primary requirement of nano-energetic materials is to obtain an efficient energy release through combustion and other processes at the nano-scale. This is regulated by tuning the proportion of the oxidizer and fuel in combusting materials during the synthesis stage so that the thermite reaction can be stoichiometrically starved or over bred for different energy releases. These materials after synthesis are then interfaced with micro-/nano-scale electromechanical devices so that they can be put to use for concentrated blast release, pulse power generation, thrust generation, energy conversion and various other applications. These nano-structured energetic materials can be utilized as propellants, explosives and pyrotechnics on the basis of their specific spatial arrangements, enactments, and presentation spaces, etc. The various methods S. Bhattacharya (&) A. K. Agarwal Department of Mechanical Engineering, Indian Institute of Technology, Kanpur 208016, India V. K. Patel Department of Mechanical Engineering, Govind Ballabh Pant Institute of Engineering and Technology, Ghurdauri, Pauri Garhwal 246001, Uttarakhand, India T. Raja Gopalan Department of Mechanical Engineering, Amrita School of Engineering, Coimbatore 641105, India A. K. Basu A. Saha Microsystems Fabrication Lab, Department of Mechanical Engineering, IIT Kanpur, Kanpur 208016, India © Springer Nature Singapore Pte Ltd. 2019 S. Bhattacharya et al. (eds.), Nano-Energetic Materials, Energy, Environment and Sustainability, https://doi.org/10.1007/978-981-13-3269-2_1 3 that are deployed to fabricate these energetic materials include wet chemical synthesis, DC reactive magnetron sputtering, electrocatalysis, molecular self-assembly. Since these nano-energetic materials and composites have wide scope in micro-/ nano-energetic arena of applications, the corresponding book discusses some of the detailed and novel synthesis, fabrication, characterization, tunability, storage and application aspects of these materials.
18 citations
TL;DR: In this article, the authors pointed out the influence of ultrafine aluminium (∼100nm) and nanoaluminium (<100 nm) on burning rates of the composite solid propellants comprising AP as the oxidizer.
Abstract: The nanosized powders have gained attention to produce materials exhibiting novel properties and for developing advanced technologies as well. Nanosized materials exhibit substantially favourable qualities such as improved catalytic activity, augmentation in reactivity, and reduction in melting temperature. Several researchers have pointed out the influence of ultrafine aluminium (∼100 nm) and nanoaluminium (<100 nm) on burning rates of the composite solid propellants comprising AP as the oxidizer. The inclusion of ultrafine aluminium augments the burning rate of the composite propellants by means of aluminium particle’s ignition through the leading edge flames (LEFs) anchoring above the interfaces of coarse AP/binder and the binder/fine AP matrix flames as well. The sandwiches containing 15% of nanoaluminium solid loading in the binder lamina exhibit the burning rate increment of about 20–30%. It was noticed that the burning rate increment with nanoaluminium is around 1.6–2 times with respect to the propellant compositions without aluminium for various pressure ranges and also for different micron-sized aluminium particles in the composition. The addition of nano-Al in the composite propellants washes out the plateaus in burning rate trends that are perceived from non-Al and microaluminized propellants; however, the burning rates of nanoaluminized propellants demonstrate low-pressure exponents at the higher pressure level. The contribution of catalysts towards the burning rate in the nanoaluminized propellants is reduced and is apparent only with nanosized catalysts. The near-surface nanoaluminium ignition and diffusion-limited nano-Al particle combustion contribute heat to the propellant-regressing surface that dominates the burning rate. Quench-collected nanoaluminized propellant residues display notable agglomeration, although a minor percentage of the agglomerates are in the 1–3 µm range; however, these are within 5 µm in size. Percentage of elongation and initial modulus of the propellant are decreased when the coarse AP particles are replaced by aluminium in the propellant composition.
6 citations
References
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TL;DR: In this paper, a new approach to the production of nanocomposites of some energetic materials ( ammonium nitrite, cyclotrimethylene trinitramine (RDX), and aluminum) by the vacuum co-deposition technique is presented.
Abstract: Nanophase materials and nanocomposites, characterized by an ultra fine grain size (less than 100 nm) have attracted wide spread interest in recent years by virtue of their unusual mechanical, electrical, optical, magnetic, and energetic properties. Studies have shown that the thermal behavior of nano-scaled materials is quite different from micron-sized powders. Nanosized metallic and explosive powders have been used as solid propellant and explosive mixtures to increase efficiency. At the same time recent studies reveal that the presence of nanosized metals in propellants does not necessary translate into an increased burning rate and burning temperature. The reasons of this effect are far from being clear. This paper presents a new approach to the production of nanocomposites of some energetic materials – ammonium nitrite, cyclotrimethylene trinitramine (RDX), and aluminum – by the vacuum co-deposition technique. The thermal behavior of the synthesized nanopowder and nanocomposites is investigated. A substantial difference in burning rate of RDX nanopowder has been found in comparison to micron-sized material. Experimental results allow investigating the effects of nanosized materials on the combustion characteristics.
183 citations
TL;DR: In this paper, the important questions are how to produce a powder with specified characteristics and how to use the powder produced, and the important question is how to obtain the desired characteristics from a specified powder.
Abstract: Fine and ultra-fine powders are actively studied in pyrotechnics, explosives and propellants. The important questions are how to produce a powder with specified characteristics and how to use the powder produced.
131 citations
TL;DR: In this paper, the thermal behavior of two different Al nanopowders and a micron-sized Al powder was studied using DSC, simultaneous TG-DTA, and accelerating rate calorimetry (ARC).
Abstract: The thermal behaviour of two different Al nanopowders and a micron-sized Al powder was studied using DSC, simultaneous TG-DTA, and accelerating rate calorimetry (ARC). The results show that the reactivity of Al powder increases as the particle size decreases. The thermal stability of the smaller Al nanopowder (Als) in water and in a humid atmosphere was determined using ARC and TG-DTA, respectively. Atomic Absorption Spectrometry (AAS), X-Ray Photoelectron Spectrometry (XPS) and Auger Electron Spectrometry (AES) were used to characterize the surface chemistry of Alex. The outgassing behaviour for mixtures of RDX and the various Al powders was investigated using TG-DTA-FTIR-MS. Evolution of NO2 and N2O from a chemical interaction between Al nanopowders and RDX was observed. The effect of Als and Alex on the thermal stability of TNT, RDX, Comp B, and AP was determined using ARC. Addition of Als significantly lowered the onset temperature for TNT and RDX decomposition. Electrostatic discharge (ESD) sensitivities of Al nanopowders and their mixtures with TNT, Comp B, RDX and AP were determined. The results show that the AP/Als mixture is very sensitive to ESD. Standard dust explosibility tests demonstrated that Alex is highly explosible.
121 citations
10 Jan 2005
40 citations
07 Jul 2002
TL;DR: In this article, an experimental investigation was carried out to evaluate the combustion behavior of aluminized, ammonium perchlorate composite propellants, with various Al particle sizes, including bimodal aluminum size distributions using ultra-fine aluminum (UFAl, ~0.1μm) as the fine component.
Abstract: An experimental investigation was carried out to evaluate the combustion behavior of aluminized, ammonium perchlorate composite propellants, with various Al particle sizes, including bimodal aluminum size distributions using ultra-fine aluminum (UFAl, ~0.1μm) as the fine component. It was found that the burning rate could be increased several fold with UFAl, with major increases produced by an aluminum blend with only 20% UFAl under some conditions. Presence of UFAl had a major effect on the appearance of the flame, and on the amount and size distribution of the Al2O3 product particles. Explanations of the burning rate effect of fine Al are proposed that involve rapid Al combustion, and include Al ignition and oxidizer availability as important variables. Some possible causes of the effects on the product oxide size are also discussed. * Ph.D Candidate. Student Member. Email: allandokhan@hotmail.com † Regent Professor Emeritus. Fellow AIAA Member. Associate Professor. Senior AIAA Member. § Senior Research Engineer INTRODUCTION Powdered aluminum is used in solid rocket propellants because of the high-energy release in its oxidation to Al2O3, and its high density compared to other ingredients. While the condensed state of the product is generally disadvantageous, the droplets are effective damping agents for oscillatory combustor instabilities. The combustion of conventional sized Aluminum (15μm-95μm) does not ordinarily contribute much to the propellant burning rate because its burning occurs relatively far from the propellant surface. Introduction of aluminum (Al) to an already fuel rich system tends to reduce burning rates. In this report, one of the primary goals is evaluation of a potential method to enhance heating of the burning surface (and thus increase the burning rate) by producing Al burning closer to surface. In pursuing this goal, it should be recognized that the behavior of Al in the propellant combustion zone has been studied extensively because it is important to combustion efficiency, combustion stability, slag formation, two phase flow losses, component erosion, and potentially to burning rate. In order to understand the results of the present study, it is necessary to be aware of several properties and behavior of Al and its oxides as described in Refs. 1-5 and summarized below. Unlike other propellant ingredients, Al does not vaporize at the temperatures present in the propellant surface (~600°C). It is seen to adhere to the burning surface temporarily, giving an opportunity for particle concentration and adhesion. This creates an opportunity for formation of aggregates of various sizes (2 to 10 particles) that are converted to burning “agglomerate” droplets as they move into high temperature regions of the combustion zone. Aluminum is extraordinarily reactive, but this oxidation is impeded at low and intermediate temperatures by formation of an impervious oxide “skin” on the particles that does not melt until a temperature of 2047°C is reached. Some reaction occurs at the melting point of the Al (660°C), due to its expansion (~6%) during phase change. This causes leaking and surface oxidation of molten Al at the cracks in the oxide skin (Fig. 4 of Ref. 2). This creates an opportunity for concentrations of particles (now droplets confined in their oxide skins) to sinter together into “aggregates.” When the aggregates reach 2047°C, the surface tension of the Al converts the aggregate to one or more droplets (agglomerates) and the surface tension of the insoluble oxide causes it to retract to one or more lobes on the aluminum droplet surface. The extent of aggregation is affected by the degree of initial Al concentration within the packing pattern of the larger AP particles in the propellant, and by proximity of high temperature sites in the array of flamelets above the surface. These factors are controllable to some extent by selection of oxidizer and Al particle size distribution, and the sintering is affected appreciably by the initial thickness of the oxide skin.
22 citations