硼的添加对Mg_2Ni储氢合金吸放氢性能的影响

Effect of Boron Addition on Hydriding/Dehydriding Properties of Mg_2Ni Hydrogen Storage Alloys

镁系储氢合金有着价格低廉、储氢量大等优点,作为机载储氢材料有着广泛的应用前景,但其过高的氢分解温度,过慢的分解速度等缺点制约着实际应用。采用机械球磨制备出Mg2Ni-xB(x=0%,1%,5%,10%,15%)系列储氢合金。通过XRD分析了合金的物相结构,采用P-C-T测试仪测定了合金的吸放氢性能,研究了添加不同含量的B对Mg2Ni合金吸放氢性能的影响。研究结果表明,B的添加对合金在200和300℃下吸放氢性能的改善作用不明显,但添加B的合金在400℃下的吸氢量均较Mg2Ni高,B的添加量由1%增至15%的合金吸氢量分别为3.09%,3.00%,2.81%,2.84%,而Mg2Ni的吸氢量则只有2.60%。随着B含量的增加,含B合金吸氢量略有降低;在含B的试样中,含5%B的合金吸氢速率最大,仅需180 s便能完成吸氢。所有含B合金的放氢平台均较Mg2Ni高且较为平坦。本次实验表明,B的添加量对合金性能的提升存在一个最优值,本次实验结果显示,添加5%B相对较好地改善合金的储氢性能,提高合金吸氢量和放氢平台压的同时能保持较快的吸氢速率。

With the advantages of low price and high capacity,Mg-based hydrogen storage alloys became the promising candidate for competitive hydrogen storage.But the inherence disadvantages,such as the high temperature of hydride decomposition,slow absorption/desorption kinetics,hindered the application of the Mg-based hydrogen storage alloys.Mg2Ni-xB（x=0%,1%,5%,10%,15%） series alloys were synthesized by mechanical grinding.The effects of boron addition on the hydriding/dehydriding performances of Mg2Ni hydrogen storage alloys were studied.The types of phases in the alloys were determined by X-ray diffraction and the hydrogen storage properties of the alloys were measured by pressure-composition isotherm（P-C-T） method.The results showed that the improvement of boron addition to the hydrogen storage properties of Mg2Ni was unobvious at 200 and 300 ℃.At 400 ℃,in the case of the alloys containing boron,the hydrogen absorption capacities decreased with the increase of the contents of boron while were higher than that of Mg2Ni.Compared with the 2.60% of Mg2Ni,the capacities of the alloys containing boron were 3.09%,3.00%,2.81%,2.84% respectively.The hydrogen absorption rate of Mg2Ni-5%B was the fastest of 2MgNi-xB series alloys;it only took 180 s to complete the hydriding.The plateau pressure of the alloys containing boron was higher and flatter than that of Mg2Ni at 400 ℃.The results showed that the level of addition of boron for improving the hydrogen storage properties of Mg2Ni had an optimum value.The alloy with boron addition of 5% had the best properties.It provided the highest hydrogen capacity and fastest hydride rate,as well as higher plateau pressure.