Ti_(1.0)Mn_(0.9)V_(1.1)的添加对氢化燃烧合成复合机械球磨制备Mg_(95)Ni_5放氢性能的影响

Effects of Ti_(1.0)Mn_(0.9)V_(1.1) on hydrogen desorption property of Mg_(95)Ni_5 prepared by hydriding combustion synthesis and mechanical milling

采用氢化燃烧合成法(HCS)制备Mg95Ni5+x%Ti1.0Mn0.9V1.1(x=0、10、20和30)复合物,然后将氢化燃烧合成产物进行机械球磨(MM)得到镁基复合储氢材料。采用压力-浓度-温度(pcT)曲线、X线衍射仪(XRD)和扫描电子显微镜(SEM)研究材料的放氢性能、相结构、表面形貌以及颗粒化学成分。研究表明:添加30%(质量分数)Ti1.0Mn0.9V1.1可使Mg95Ni5的HCS+MM产物的放氢性能达到最佳,在523 K时1 200 s内就可完全放氢,放氢量达5.71%,同时放氢反应的表观活化能从148.20 kJ/mol降低到129.69 kJ/mol,这主要归因于Ti1.0Mn0.9V1.1的添加提高了氢在产物中的扩散能力以及对镁基氢化物放氢的氢泵作用。

Mg95Ni5 ＋x% Ti1.0 Mn0.9V1.1 （ x = 0, 10,20, and 30） composites were prepared by hydriding combustion synthesis （HCS） and the HCS products were mechanically milled （MM） to obtain Mg-based hydrogen-storage composites.The dehydriding properties, phase structure, surface morphology, and particle composition were studied by pressure-composition-temperature （pcT） ,X-ray diffraction （XRD） and scanning electron microscopy （SEM）.Results showed that addition of 30% （mass fraction） Ti1.0Mn0.9V1.1 exhibited the best hydrogen desorption property for the HCS＋MM product of Mg95Nis, which could completely desorb 5.71% H2 in 1 200 s at 523 K.The apparent dehydrogenation activation energy of the system was decreased to 129.69 kJ/mol from 148.20 kJ/mol of Mg95Nis.The improvement of the hydrogen desorption property could be attributed to the enhancement of hydrogen diffusion and the ＂hydrogen pumping＂ of Ti1.0Mn0.9V1.1.