Hydrogen absorption and desorption kinetics of Ag–Mg–Ni alloys
Hydrogen absorption and desorption kinetics of Ag–Mg–Ni alloys
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DOI：
10.1016/j.ijhydene.2003.10.002
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发表时间：
2004-07
影响因子：
7.2
通讯作者：
Qian Li;K. Chou;Q. Lin;Lijun Jiang;F. Zhan
中科院分区：
文献类型：
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作者：
Qian Li;K. Chou;Q. Lin;Lijun Jiang;F. Zhan
研究了两相（α -β）区氢化燃烧合成法制备的Mg2−xAgxNi （x=0.05, 0.1）储氢合金在523 ~ 573 K温度范围内的吸氢/脱氢动力学。从随时间变化的A/D曲线中提取了氢/脱氢反应速率常数。用不同速率方程拟合得到的氢的A/D动力学曲线，揭示了氢/D过程的机理。建立了反应速率常数与温度的关系。结果表明，三维扩散过程主导了氢的A/D过程。在523 ~ 573 K的两相（α -β）共存区，Mg1.95Ag0.05Ni合金的H/D过程表观活化能分别为63±5和61±7 kJ/mol H2in， Mg1.9Ag0.1Ni合金的H/D过程表观活化能分别为52±2 kJ/mol H2in和50±2 kJ/mol H2in。随着Ag - mg - ni合金中Ag含量的增加，表观能降低，反应速度加快。可以合理地解释，Ag的加入改善了Mg2Ni的氢化动力学。
The hydrogen absorption/desorption (A/D) kinetics of hydrogen storage alloys Mg2−xAgxNi (x=0.05, 0.1) prepared by hydriding combustion synthesis in two-phase (α–β) region in the temperature range of 523–573 K have been investigated. The hydriding/dehydriding (H/D) reaction rate constants were extracted from the time-dependent A/D curves. The obtained hydrogen A/D kinetic curves were fitted using various rate equations to reveal the mechanism of the H/D processes. The relationships of rate constant with temperature were established. It was found that the three-dimensional diffusion process dominates the hydrogen A/D. The apparent activation energies of 63±5 and 61±7 kJ/mol H2in Mg1.95Ag0.05Ni alloy and 52±2 kJ/mol H2and of 50±2 kJ/mol H2in Mg1.9Ag0.1Ni alloy were found for the H/D processes in two-phase (α–β) coexistence region from 523 to 573 K , respectively. With the increasing content of Ag in Ag–Mg–Ni alloys, the apparent energy was decreased and the reaction rate was faster. It is reasonable to explain that the hydriding kinetics of Mg2Ni was improved by adding Ag.