Effect of Al generated in situ in hydriding on the dehydriding properties of Mg-Al alloys prepared by hydriding combustion synthesis and mechanical milling
Effect of Al generated in situ in hydriding on the dehydriding properties of Mg-Al alloys prepared by hydriding combustion synthesis and mechanical milling
复制标题
氢化中原位生成的Al对氢化燃烧合成和机械球磨制备的Mg-Al合金脱氢性能的影响
DOI：
10.1016/j.jallcom.2018.04.023
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发表时间：
2018
影响因子：
6.2
通讯作者：
Li Liquan
中科院分区：
文献类型：
--
作者：
Luo Shicheng;Han Huihui;Huang Haixiang;Zhang Jiguang;Liu Yana;Zhu Yunfeng;Zhang Yao;Xu Bin;Li Liquan
研究了原位生成的Al* 对氢化燃烧合成（HCS）和机械球磨（MM）法制备的Mg-Al合金放氢性能的影响。热分析结果表明，在HCS（或MM）工艺中加入20at%Al后，MgH 2的放氢峰温度降低了25 °C（或11 °C），但仍存在17 MgH 2 + 12 Al */Al → Al 12 Mg 17 + 17 H2的放氢反应。在300 °C下等温放氢3 h表明，HCS+ MM-MgH 2需要81 min才能解吸50%的氢，而HCS+ MM-Mg 80 Al *20仅需要24 min。MgH 2放氢的表观活化能从HCS+ MM-MgH 2的144.3 ± 7.19 kJ/mol降低到HCS + MM-Mg 90 Al *10的118.8 ± 6.73 kJ/mol。扫描电子显微镜/能谱和X射线光电子能谱分析表明，Al 12 Mg 17在HCS中原位生成的Al* 由于分布均匀、缩短反应扩散距离、提供与MgH 2反应的未氧化表面以及Al* 的高化学活性，可显著降低MgH 2-Al复合材料的放氢温度，改善放氢动力学。
In this work, the effects of Al* generated in situ in hydriding on the dehydriding of Mg-Al alloys prepared by Hydriding Combustion Synthesis (HCS) and Mechanical Milling (MM) were studied. Thermal analysis showed that the peak dehydriding temperature of MgH2was reduced by 25 °C (or 11 °C) when 20 at% Al was added in HCS (or MM) process, even though, the same dehydriding reaction of 17MgH2+ 12Al*/Al → Al12Mg17+ 17H2was observed. Isothermal dehydriding at 300 °C for 3 h demonstrated that it took 81 min for HCS+MM-MgH2to desorb 50% of hydrogen, while only 24 min was required for HCS+MM-Mg80Al*20. The apparent activation energy for dehydriding of MgH2was reduced from 144.3 ± 7.19 kJ/mol for HCS+MM-MgH2to 118.8 ± 6.73 kJ/mol for HCS+MM-Mg90Al*10. The scanning electron microscopy/energy dispersive spectroscopy and X-ray photoelectron spectroscopy analyses revealed that the Al* in situ generated from the hydriding of Al12Mg17in HCS would significantly decrease dehydriding temperature and improve dehydriding kinetics of the MgH2-Al composites because of a uniform distribution, the shortening reaction diffusion length, providing unoxidized surfaces to react with MgH2and the high chemical activity of Al*.