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铁虫 (正式写手)

应助: 1 (幼儿园)
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帖子: 306
在线: 68.5小时
虫号: 4532612
注册: 2016-03-23
专业: 高分子合成化学

[交流] 铝水分离反应动力学已有1人参与

The energy producing aluminum-water split reaction is characterized experimentally using microcalorimetry. The rates of heat release during the reaction at two fixed temperatures, 303 and 313 K, were measured for spherical aluminum powders placed in liquid water. Fully and partially reacted powders were characterized using electron microscopy and x-ray diffraction. Experiments were performed with three commercial powders with nominal sizes of 3-4.5, 10-14, and 17-30 μm. The observed reaction could be broken down into several parts, including an induction time, two stages of relatively rapid reaction, and reaction termination. Initially, particles grow bayerite layers which later sinter together forming continuous aluminumbayerite composites. The significance of the first of the rapid reaction stages increased for experiments at the higher temperature. It was also observed that finer powders exhibited a faster and more complete reaction. Experimental data were processed using a simplified kinetic model reported in the literature to assess the diffusion coefficient describing the reaction rate-limiting process: transport of hydroxo complexes of aluminum through a growing porous layer of bayerite. The calculated diffusion coefficient was in the range expected for the experimental temperatures. However, its dependence on the powder particle size and on the reaction time indicate that the current model is inadequate for describing the present experiments.

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