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International Journal of Energetic Materials and Chemical Propulsion

Publicado 6 números por año

ISSN Imprimir: 2150-766X

ISSN En Línea: 2150-7678

The Impact Factor measures the average number of citations received in a particular year by papers published in the journal during the two preceding years. 2017 Journal Citation Reports (Clarivate Analytics, 2018) IF: 0.7 To calculate the five year Impact Factor, citations are counted in 2017 to the previous five years and divided by the source items published in the previous five years. 2017 Journal Citation Reports (Clarivate Analytics, 2018) 5-Year IF: 0.7 The Immediacy Index is the average number of times an article is cited in the year it is published. The journal Immediacy Index indicates how quickly articles in a journal are cited. Immediacy Index: 0.1 The Eigenfactor score, developed by Jevin West and Carl Bergstrom at the University of Washington, is a rating of the total importance of a scientific journal. Journals are rated according to the number of incoming citations, with citations from highly ranked journals weighted to make a larger contribution to the eigenfactor than those from poorly ranked journals. Eigenfactor: 0.00016 The Journal Citation Indicator (JCI) is a single measurement of the field-normalized citation impact of journals in the Web of Science Core Collection across disciplines. The key words here are that the metric is normalized and cross-disciplinary. JCI: 0.18 SJR: 0.313 SNIP: 0.6 CiteScore™:: 1.6 H-Index: 16

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RECENT STUDIES OF THE KINETICS OF SOLID BORON GASIFICATION BY B2O3(g) AND THEIR CHEMICAL PROPULSION IMPLICATIONS

Volumen 2, Edición 1-6, 1993, pp. 113-132
DOI: 10.1615/IntJEnergeticMaterialsChemProp.v2.i1-6.50
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SINOPSIS

Interfacial kinetics are likely to play a rate-limiting role in the combustion of small boron particles and yet little is known about boron gasification by B2O3(g), which may be important because of its formation from O2 in the boundary layer near the gasifying surface. For these reasons, intrinsic kinetics of the high temperature B2O3(g)/B(s) reaction were investigated utilizing newly designed flow reactor techniques, together with a 'real-time' (boron) element detection technique based on microwave-induced plasma emission spectroscopy. Known amounts of the gaseous reactant B2O3 were generated using a resistively heated Knudsen effusion source operating in a high velocity argon gas background. Reaction rate measurements on a joule-heated boron filament covered the surface temperature interval 1330-2050 K at BB2O3 partial pressures between 6·10−3 and 6·10−2 Pa. Results revealed remarkably high reaction probabilities over a broad temperature range (ca. 1400-2000 K) with a maximum close to unity, at ca. 1950 K, much higher than that for the O2(g)/B(s) reaction and comparable to that previously observed (locally) for O-atom attack of boron. Transition conditions for 'passivation' of the B2O3(g)/B(s) reaction were identified experimentally and found to be in qualitative agreement with quasi-equilibrium model predictions, which also indicate that the dominant product species in the "active" regime were (BO)2 over the intermediate temperature regime, ca. 1050-1500 K, and BO in the high temperature regime, ca. 1500-2200 K. Mechanistic implications of these results include a high sticking (O-atom deposition) probability for B2O3 on solid boron, but with a fall-off above ca. 2000 K, causing e to drop precipitously despite the stability of BO(g) at these temperatures. These kinetic data are used to discuss the expected sequence of rate-controlling processes for the combustion of individual B(s) particles in air under typical ramjet conditions. While most previous boron particle combustion and extinction laboratory experiments have been performed in the regime of gas-phase diffusion control, under conditions of actual ramjet interest the gas/solid kinetics for the efficient B2O3(g)/B(s) reaction and the slower O2(g)/B(s) reaction, as well as non-continuum transport effects, become rate-limiting.

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