دورية أكاديمية
Ignition and self-propagating reactions in Al/Pt multilayers of varied design.
| العنوان: | Ignition and self-propagating reactions in Al/Pt multilayers of varied design. |
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| المؤلفون: | Adams, D. P., Reeves, R. V., Abere, M. J., Sobczak, C., Yarrington, C. D., Rodriguez, M. A., Kotula, P. G. |
| المصدر: | Journal of Applied Physics; 2018, Vol. 124 Issue 9, pN.PAG-N.PAG, 14p, 1 Black and White Photograph, 1 Diagram, 5 Charts, 10 Graphs |
| مصطلحات موضوعية: | SELF-propagating high-temperature synthesis, MULTILAYERS, STOICHIOMETRY, THERMODYNAMICS, MASS transfer, ALUMINUM, PLATINUM |
| مستخلص: | The different rate-limiting processes underlying ignition and self-propagating reactions in Al/Pt multilayers are examined through experiments and analytical modeling. Freestanding, ∼1.6 μm-thick Al/Pt multilayers of varied stoichiometries and nanometer-scale layer thicknesses ignite at temperatures below the melting point of both reactants (and eutectics) demonstrating that initiation occurs via solid-state mixing. Equimolar multilayers exhibit the lowest ignition temperatures when comparing structures having a specific bilayer thickness. An activation energy of 76.6 kJ/mol at. associated with solid state mass transport is determined from the model analysis of ignition. High speed videography shows that equimolar Al/Pt multilayers undergo the most rapid self-sustained reactions with wavefront speeds as large as 73 m/s. Al- and Pt-rich multilayers react at reduced rates (as low as 0.3 m/s), consistent with reduced heat of reaction and lower adiabatic temperatures. An analytical model that accounts for key thermodynamic properties, preliminary mixing along interfaces, thermal transport, and mass diffusion is used to predict the wavefront speed dependencies on bilayer thickness. Good fits to experimental data provide estimates for activation energy (51 kJ/mol at.) associated with mass transport subject to high heating rates and thermal diffusion coefficient of premixed interfacial volumes (2.8 × 10−6 m2/s). Pt dissolution into molten Al is identified as a rate-limiting step underlying high temperature propagating reactions in Al/Pt multilayers. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: | Complementary Index |
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