Altering combustion of silicon/polytetrafluoroethylene with two-step mechanical activation

Terry, Brandon C.; Son, Steven F.; Groven, Lori J.

doi:10.1016/j.combustflame.2014.11.005

Cited by 21 publications

(8 citation statements)

References 37 publications

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“…During this fast reaction process, which is generally in the range of hundreds of microseconds, the highly exothermic reaction of the PTFE-Si EMs releases a huge amount of heat and gaseous SiF 4 product [ 33 ]. For the Si/PTFE mixture with a similar composition, it has been reported that the average combustion temperature is in the range of 1708 to 1889 K [ 34 ], which is comparable to the melting point of SnO 2 (1630 ℃); hence, the released heat melted the SnO 2 particles and induced an instantaneous temperature rise at the reaction zone. This temperature rise caused a rapid expansion of the SiF 4 gas and the subsequent pressure rise.…”

Section: Resultsmentioning

confidence: 99%

Energetic-Materials-Driven Synthesis of Graphene-Encapsulated Tin Oxide Nanoparticles for Sodium-Ion Batteries

et al. 2021

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By evenly mixing polytetrafluoroethylene-silicon energetic materials (PTFE-Si EMs) with tin oxide (SnO2) particles, we demonstrate a direct synthesis of graphene-encapsulated SnO2 (Gr-SnO2) nanoparticles through the self-propagated exothermic reaction of the EMs. The highly exothermic reaction of the PTFE-Si EMs released a huge amount of heat that induced an instantaneous temperature rise at the reaction zone, and the rapid expansion of the gaseous SiF4 product provided a high-speed gas flow for dispersing the molten particles into finer nanoscale particles. Furthermore, the reaction of the PTFE-NPs with Si resulted in a simultaneous synthesis of graphene that encapsulated the SnO2 nanoparticles in order to form the core-shell nanostructure. As sodium storage material, the graphene-encapsulated SnO2 nanoparticles exhibit a good cycling performance, superior rate capability, and a high initial Coulombic efficiency of 85.3%. This proves the effectiveness of our approach for the scalable synthesis of core-shell-structured graphene-encapsulated nanomaterials.

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Section: Resultsmentioning

confidence: 99%

Energetic-Materials-Driven Synthesis of Graphene-Encapsulated Tin Oxide Nanoparticles for Sodium-Ion Batteries

et al. 2021

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“…Mechanical, chemical, and mechano-chemical activation processes offer breakthrough opportunities for the development of new energetic composites [22][23][24][36][37][38][39][45][46][47][48]. The use of mechanical and mechano-chemical activation processes enables coupling ingredients featuring relatively low compatibility [24,45].…”

Section: Regression Rate Performance and Metal Additivesmentioning

confidence: 99%

“…Activated Al powders typically feature reactivity tailoring of the starting material by chemical, mechanical, and mechano-chemical methods [22][23][24]. Activation techniques modify the powder surface characteristics (such as SSA and/or composition), and/or the particle morphology, size, and composition [22][23][24][36][37][38][45][46][47][48]. In particular, activation processes enable the creation of composite additives such as dual-metal [38,48] or metal-oxidizer compositions [45,48], offering wide possibilities for additive reactivity tailoring.…”

Section: Introductionmentioning

confidence: 99%

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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“…Также можно отметить, что фторполимеры (фторкаучуки) достаточно широко применяются в рецептуре пиротехнических составов [10,11], где они играют роль и окислителя, обеспечивающего активацию горения, и связующего. Кроме того, фторполимеры достаточно широко применяются в качестве окислителей для пиротехнических средств на основе кремния [6,12].…”

Section: Introductionunclassified

Оптическое И Электронно-Пучковое Инициирование Пленок Пористого Кремния С Различным Содержанием Окислителя И Графена

Побережная¹,

Фрейман²,

Илюшин³

et al. 2022

Журнал Технической Физики

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Laser and electron-beam initiation of the combustion process of energy-saturated composite films were studied. Composites were produced from porous silicon, a fluorine-containing polymer, and graphene. It is shown that the impact of a high-current electron beam of nanosecond duration does not lead to the excitation of the combustion process. Moreover, the process of film combustion during laser initiation is accompanied in some cases by the appearance of a zone of secondary flame and white smoke.

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Altering combustion of silicon/polytetrafluoroethylene with two-step mechanical activation

Cited by 21 publications

References 37 publications

Energetic-Materials-Driven Synthesis of Graphene-Encapsulated Tin Oxide Nanoparticles for Sodium-Ion Batteries

Energetic-Materials-Driven Synthesis of Graphene-Encapsulated Tin Oxide Nanoparticles for Sodium-Ion Batteries

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

Оптическое И Электронно-Пучковое Инициирование Пленок Пористого Кремния С Различным Содержанием Окислителя И Графена

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