Mg_(17)Al_(12)基储氢合金的表面复相改性

Multi-phase Surface Modification of Mg_(17)Al_(12)-Based Hydrogen Storage Alloys

采用机械球磨法制备Mg17Al12合金,系统研究了球磨时间对Mg17Al12形成过程的影响;并以球磨12 h的Mg17Al12合金为基体,添加5%、10%(质量分数)的Ni、Cu单质,通过机械球磨对合金进行表面复相改性。采用P-C-T测试仪测定合金的储氢性能,研究添加不同质量分数的单质对Mg17Al12合金储氢性能的影响。结果表明:球磨12 h Mg17Al12的吸氢速率较慢,吸氢时间较长,需在1400 min达到最大吸氢量为4.1%(质量分数),接近其理论吸氢量4.4%,Mg17Al12的吸放氢过程是可逆的。Cu对Mg17Al12进行表面复相改性,可以显著改善其吸氢动力学性能,添加5%Cu和10%Cu的合金在623 K,240 min的吸氢量分别为4.07%和3.9%。经过Cu和Ni复相改性后的Mg17Al12具有较好的放氢性能,添加5%Cu合金在553 K放出3%的氢气。Ni对Mg17Al12进行表面复相改性,对其性能有一定的提高,但是和Cu相比,并不明显。

Mg17Al12 alloys were prepared by mechanical ball milling for systematical studying the influence of milling time on the information of Mg17Al12. In order to modify the surface performances of the alloys, 5% （mass fraction） or 10% of simple substances （Ni and Cu） were added into Mg17Al12 alloys mechanically milled for 12 h. The storage properties of the alloys were determined by P-C-T apparatus. The effects of different mass fraction simple substances on the hydrogen storage properties of the alloys were investigated. The results show that the Mg17Al12 has a slow rate of absorbing hydrogen and a long-term absorption process, the maximum reversible storage capacity reaches 4.1wt% after 1400 min which is closed to the theoretical one （4.4wt%）. Cu can modify the surface performance and enhance the kinetics markedly. The alloy with 5%Cu has a hydrogen absorption of 4.07wt% at 623 K in 180 min as the alloy with 10%Cu the hydrogen absorption of 3.9wt%. Mg17Al12 modified by adding Cu and Ni has a better absorption performance, as the alloy with 5% Cu can desorb 3wt% hydrogen at 553 K. Ni can modify the surface performance and enhance the properties, too. But its effect is not obvious compared to that of Cu.