Accelerated ageing of micron- and nano-sized aluminum powders: Metal content, composition and non-isothermal oxidation reactivity

Paravan, Christian; Verga, A; Maggi, F.; Galfetti, L.

doi:10.1016/j.actaastro.2018.08.001

Cited by 33 publications

(13 citation statements)

References 23 publications

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“…Al is widely used to increase the energy and raise the flame temperature in rocket propellants because of its high combustion enthalpy, easy availability, low toxicity, and good stability in energetic applications, such as propellants, pyrotechnics, and explosives. Especially, nano-sized Al (nAl) is broadly exploited to improve performance incrementing the burning rate and combustion Nanomaterials 2020, 10, 1039 2 of 22 efficiency of energetic systems, leading to shorter ignition delays and shorter agglomerate burning times with respect to propellants containing µAl [6][7][8][9]. In this paper, the developments and achievements in the preparation and performance of Al-based nano-CEMs are reviewed.…”

Section: Introductionmentioning

confidence: 99%

Al-Based Nano-Sized Composite Energetic Materials (Nano-CEMs): Preparation, Characterization, and Performance

Pang¹,

Fan²,

Wang³

et al. 2020

Nanomaterials

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As one of the new types of functional materials, nano-sized composite energetic materials (nano-CEMs) possess many advantages and broad application prospects in the research field of explosives and propellants. The recent progress in the preparation and performance characterization of Al-based nano-CEMs has been reviewed. The preparation methods and properties of Al-based nano-CEMs are emphatically analyzed. Special emphasis is focused on the improved performances of Al-based nano-CEMs, which are different from those of conventional micro-sized composite energetic materials (micro-CEMs), such as thermal decomposition and hazardous properties. The existing problems and challenges for the future work on Al-based nano-CEMs are discussed.

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Section: Introductionmentioning

confidence: 99%

Al-Based Nano-Sized Composite Energetic Materials (Nano-CEMs): Preparation, Characterization, and Performance

Pang¹,

Fan²,

Wang³

et al. 2020

Nanomaterials

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“…However, there are drawbacks limiting their application in additive manufacturing. One of these disadvantages is the increased sensitivity to the effects of oxidizing and corrosive environments due to the large specific surface area of the nanomaterials [ 89 , 90 ]. This disadvantage leads to a significant decrease in the content of active aluminum, thus lowering its energy characteristics in the energy system compositions.…”

Section: Promising Methods For Improving the Safety And Manufacturability Of Nanopowders For 3d Technologies Of High-energy Materialsmentioning

confidence: 99%

Review of the Problems of Additive Manufacturing of Nanostructured High-Energy Materials

et al. 2021

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This article dwells upon the additive manufacturing of high-energy materials (HEM) with regards to the problems of this technology’s development. This work is aimed at identifying and describing the main problems currently arising in the use of AM for nanostructured high-energy materials and gives an idea of the valuable opportunities that it provides in the hope of promoting further development in this area. Original approaches are proposed for solving one of the main problems in the production of nanostructured HEM—safety and viscosity reduction of the polymer-nanopowder system. Studies have shown an almost complete degree of deagglomeration of microencapsulated aluminum powders. Such powders have the potential to create new systems for safe 3D printing using high-energy materials.

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“…Conventional Al powders feature micron-sized spherical particles [25]. The µAl is typically air-passivated, thus showing a core-shell particle structure with the metal core surrounded by an amorphous Al 2 O 3 layer [26][27][28]. The micrometric size, together with the particle morphology and the specific surface area (SSA) <1 m 2 /g, yields µAl high metal content (typically >95 wt.%), relatively low reactivity, and inherent safety (i.e., high ignition temperature, reduced dispersion in air, and limited aging influence) [28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

“…The µAl is typically air-passivated, thus showing a core-shell particle structure with the metal core surrounded by an amorphous Al 2 O 3 layer [26][27][28]. The micrometric size, together with the particle morphology and the specific surface area (SSA) <1 m 2 /g, yields µAl high metal content (typically >95 wt.%), relatively low reactivity, and inherent safety (i.e., high ignition temperature, reduced dispersion in air, and limited aging influence) [28][29][30][31]. The reactivity of µAl can be enhanced by reducing the particle size down to the nanoscale [32][33][34][35] and by activation processes [23,24,[36][37][38][39].…”

Section: Introductionmentioning

confidence: 99%

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Nano-Sized and Mechanically Activated Composites: Perspectives for Enhanced Mass Burning Rate in Aluminized Solid Fuels for Hybrid Rocket Propulsion

Paravan

2019

Aerospace

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This work provides a lab-scale investigation of the ballistics of solid fuel formulations based on hydroxyl-terminated polybutadiene and loaded with Al-based energetic additives. Tested metal-based fillers span from micron- to nano-sized powders and include oxidizer-containing fuel-rich composites. The latter are obtained by chemical and mechanical processes providing reduced diffusion distance between Al and the oxidizing species source. A thorough pre-burning characterization of the additives is performed. The combustion behaviors of the tested formulations are analyzed considering the solid fuel regression rate and the mass burning rate as the main parameters of interest. A non-metallized formulation is taken as baseline for the relative grading of the tested fuels. Instantaneous and time-average regression rate data are determined by an optical time-resolved technique. The ballistic responses of the fuels are analyzed together with high-speed visualizations of the regressing surface. The fuel formulation loaded with 10 wt.% nano-sized aluminum (ALEX-100) shows a mass burning rate enhancement over the baseline of 55% ± 11% for an oxygen mass flux of 325 ± 20 kg/(m2∙s), but this performance increase nearly disappears as combustion proceeds. Captured high-speed images of the regressing surface show the critical issue of aggregation affecting the ALEX-100-loaded formulation and hindering the metal combustion. The oxidizer-containing composite additives promote metal ignition and (partial) burning in the oxidizer-lean region of the reacting boundary layer. Fuels loaded with 10 wt.% fluoropolymer-coated nano-Al show mass burning rate enhancement over the baseline >40% for oxygen mass flux in the range 325 to 155 kg/(m2∙s). The regression rate data of the fuel composition loaded with nano-sized Al-ammonium perchlorate composite show similar results. In these formulations, the oxidizer content in the fuel grain is <2 wt.%, but it plays a key role in performance enhancement thanks to the reduced metal–oxidizer diffusion distance. Formulations loaded with mechanically activated ALEX-100–polytetrafluoroethylene composites show mass burning rate increases up to 140% ± 20% with metal mass fractions of 30%. This performance is achieved with the fluoropolymer mass fraction in the additive of 45%.

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Accelerated ageing of micron- and nano-sized aluminum powders: Metal content, composition and non-isothermal oxidation reactivity

Cited by 33 publications

References 23 publications

Al-Based Nano-Sized Composite Energetic Materials (Nano-CEMs): Preparation, Characterization, and Performance

Al-Based Nano-Sized Composite Energetic Materials (Nano-CEMs): Preparation, Characterization, and Performance

Review of the Problems of Additive Manufacturing of Nanostructured High-Energy Materials

Nano-Sized and Mechanically Activated Composites: Perspectives for Enhanced Mass Burning Rate in Aluminized Solid Fuels for Hybrid Rocket Propulsion

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