Influence of passivation on ageing of nano-aluminum: Heat flux calorimetry and microstructural studies

Pisharath, Sreekumar; Zhang, Fan; Ang, H.G.

doi:10.1016/j.tca.2016.04.022

Cited by 23 publications

(12 citation statements)

References 42 publications

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“…The ageing of Al nanoparticles increases the oxide film thickness and agglomeration, and reduces the active aluminum content, resulting in remarkable change of the physical properties, activation energy, tensile stress upon melting of nano aluminum and cracking behavior of oxide film, etc., thereby influencing its ignition performance [8][9][10][11]. Vorozhtsov et al [30] illustrated that the oxide thickness could be used to gauge the degree of oxidation, and the apparent activation energy is a function of the oxide thickness.…”

Section: Effect Of Ageing On Ignitionmentioning

confidence: 99%

“…As newly prepared Al nanoparticles are further exposed to heat, moisture, light, or other factors in practical applications, they would undergo physical and chemical transformations, i. e. ageing. The naturally aged Al nanoparticles received a considerable reduction of the active aluminum content and the reactivity, during storage over one year under natural conditions in air at room temperature and atmospheric pressure [8,9]. Moreover, the ageing of Al nanoparticles in the presence of air and humidity under strong accelerated conditions still produced a marked clustering, alterations in the particle morphology, and oxide film thickness; the major product of hydrolysis was bayerite Al(OH) 3 rather than Al 2 O 3 [10,11].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Heating Rate on Ignition Characteristics of Newly Prepared and Aged Aluminum Nanoparticles

Jin

Yang

et al. 2020

Propellants Explo Pyrotec

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Aluminum (Al) nanoparticles have been widely applied in propellants, but the ageing of Al nanoparticles will result in the degradation of propellant ignition performance. This paper experimentally investigates the ignition characteristics of newly prepared and aged Al nanoparticles, and improves the ignition performance of aged Al nanoparticles through elevating the heating rate. It was observed that, despite newly prepared or aged Al nanoparticles, their ignition included three stages: stage I – heating, stage II – melting, and stage III – evaporation. The temperature rise and time in stage I, melting temperature, and time in stage II and ignition temperature in stage III were separately discussed. It is found that the duration of each stage during the ignition of aged Al nanoparticles was much longer than that of newly prepared Al nanoparticles, testifying that ignition temperature of Al nanoparticles increased and ignition delay time elongated due to ageing. At elevated power density, the heating rate of Al nanoparticles increased, the heating, melting, and evaporating time shortened. The difference of ignition delay time between newly prepared and aged Al nanoparticles was significantly reduced. It means that the ignition performance can be improved through increasing the heating rate. Simultaneously, the energy conversation equation of each stage was built and discussed. It will be beneficial to deeply understand the ignition process and reveal the ignition mechanism of aged Al nanoparticles.

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Section: Effect Of Ageing On Ignitionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Heating Rate on Ignition Characteristics of Newly Prepared and Aged Aluminum Nanoparticles

Jin

Yang

et al. 2020

Propellants Explo Pyrotec

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“…The content of inclusions corresponded to their content in the initial wire that was used to produce the aluminum nanopowder [17]. Thus, the unstable state of aluminum nanopowders during the storage leads to their degradation, i. e. decrease in metallic aluminum content and other activity parameters; therefore, the practical application of aluminum nanopowders [5][6][7][8][9][10][11][12][13][14][15] requires solving the problem of their stability during storage.…”

Section: Short Communicationmentioning

confidence: 99%

“…%. The replacement of conventional aluminum powders in pyrotechnical compositions and rocket fuels by aluminum nanopowders with low content of metallic aluminum for the sake of improved performance is not evident [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Parameters of Aluminum Nanopowders Activity after Long‐Term Storage in an Airtight Container

Ilyin

Tikhonov

Mostovshchikov

2018

Propellants Explo Pyrotec

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The work has established the change in the activity parameters of aluminum nanopowders produced by electric explosion of a wire during their storage in an airtight container. The change in the characteristics of the nanopowders using four activity parameters was measured by benchmarking their activity after the production, passivation and keeping for 10–20 days and after their storage for 16 years. It was also established that after long‐term storage, the temperature of oxidation initiation for the nanopowders in air has increased; the increment of mass during oxidation at up to 800 °C for all specimens has increased, while the content of metallic aluminum has decreased. The electrical double layer on the surface of aluminum nanoparticles during storing even in an airtight container changes with time and does not provide the protective function. In this connection, the future application of aluminum nanopowders in high‐energy materials is not feasible without solving the problem of their stability. According to the results, electric‐explosion aluminum nanopowder is an unstable aluminum‐air system even in an airtight container.

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“…n-Al coating using nitrocellulose was also attempted to passivate as well as improve the reactivity of n-Al, before its use in Al/CuO nano-thermite 25. Pisharath et al79 reported on improved resistance to ageing from surface modification of n-Al with three different organosilanes, including aminopropyltrimethoxysilane, azidopropyltrimethoxysilane and perfluorodecyltriethoxysilane. Other n-Al coatings using carbon 80 , metallic Ni 81 , perfluoro-organic carboxylates 82 , and polymers (polyolefine and polyurethane 83 ) have also been reported.…”

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confidence: 99%

Synthesis, characterization and performance evaluation of nano-energetic composite

Tan¹

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Thermites belong to a class of energetic material comprising of a metal as a fuel and a metal oxide as the oxidizer. The research on nano-thermites has significantly emerged in the last two decades and novel ways to harness their energy with improved reactivity, reduced sensitivity and high stability remains highly desirable to date. In this work, Al/NiO nano-thermite system was studied due to their relatively gasless reaction. Gasless thermite reactions could offer potential in applications requiring little flow disturbances and vibrations. A novel self-assembly technique to promote better intermixing of the fuel-oxidizer system through surface functionalization with complimentary functional groups as well as the addition of an energetic polymer binder to reduce the sensitivity were studied. The heat release characteristics and reaction mechanism of Al/NiO nano-thermites were studied. n-Al/n-NiO with different equivalence ratio (ER) were prepared and their heat of reactions measured using a bomb calorimeter. The heat of reaction increased from a fuel lean formulation to a slightly fuel rich formulation at ER 1.2, yielding an optimized heat of reaction of 3649 J/g. Their highly exothermic nature was studied using a Differential Scanning Calorimeter (DSC). The reaction products during the different stages of the decomposition were analyzed using a powder X-ray Diffraction (XRD) to understand the reaction mechanism of this alumino-thermic reaction. Surface functionalization of n-Al and n-NiO using organosilanes with complimentary end groups (epoxide/ amino) to bring about the fuel-oxidizer self-assembly were performed. The self-assembled n-Al/n-NiO showed a better intermixing of the binary composite powder from their Scanning Electron Microscopy/Energy Dispersive X-ray (SEM/EDX) photographs. The self-assembled system displayed a larger heat release before aluminum melting as well as an increased heat release rate from their DSC profiles. The preference for reaction prior to aluminum melting (or solid-state reaction) is an indication of intimate interaction between the fuel and oxidizer. The self-assembly process was shown to increase the energy release rate of organosilane-functionalized nano-thermites in their pressure studies. The overall energy release rate of the functionalized n-Al/n-NiO was, however, not better than unfunctionalized n-Al/n-NiO.

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Influence of passivation on ageing of nano-aluminum: Heat flux calorimetry and microstructural studies

Cited by 23 publications

References 42 publications

Effect of Heating Rate on Ignition Characteristics of Newly Prepared and Aged Aluminum Nanoparticles

Effect of Heating Rate on Ignition Characteristics of Newly Prepared and Aged Aluminum Nanoparticles

Parameters of Aluminum Nanopowders Activity after Long‐Term Storage in an Airtight Container

Synthesis, characterization and performance evaluation of nano-energetic composite

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