(1. 上海大学 材料科学与工程学院,上海 200072;2. 北京科技大学 冶金与生态工程学院,北京 100083)
摘 要: 利用新动力学模型分析了第三组元Co和Fe取代Ni后对Mg-Mg2Ni吸氢反应动力学的影响规律,探讨其吸氢反应的控速环节,并求解出活化能,同时验证该新模型同样适用于该体系的动力学研究。结果表明:Mg-Mg2Ni1−xMex (Me=Co, Fe; x=0, 0.1, 0.3)氢化反应的控速环节是氢在氢化物层的扩散步骤,Co和Fe取代Ni后对Mg-Mg2Ni的氢化反应速率有影响,但未改变其吸氢反应动力学机制,理论预报值与实验实测值较符合;对于相同吸氢条件,同等取代量的Mg-Mg2Ni1−xCox的特征吸氢时间比 Mg-Mg2Ni1−xFex的低,说明Co比Fe取代Ni更有利于提高材料的氢化反应速率。
关键字: Mg-Mg2Ni1−xMex;储氢合金;氢化反应;动力学
(1. School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China;2. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China)
Abstract:A new kinetics model proposed was applied to investigate the effect of additives (Co and Fe) on the hydriding kinetic properties of composites based on Mg and Mg2Ni. Much attention was paid to discuss the rate-controlled step, and the reaction activation energy was calculated. The results show that this model is validated by comparison of these calculation results with experimental data. Its kinetic mechanism was well established and its rate-limited step in the hydriding reaction of Mg-Mg2Ni1−xMex composite (Me=Co, Fe; x=0, 0.1, 0.3) is hydrogen diffusion in the metal hydride, which means the additives (Co and Fe) can impose on the hydriding rate without changing the kinetic mechanism of the hydriding reaction. Under the same conditions for hydrogen absorption, the same amount of the additive Co is more profitable to promote the hydriding rate of the composites based on Mg and Mg2Ni than the same amount of the additive Fe on account of the hydriding characteristic time, and the activation energy of the former is smaller than that of the latter.
Key words: Mg-Mg2Ni1−xMex; hydrogen storage alloys; hydriding reaction; kinetic