固-气反应球磨制备纳米晶MgH2的研究

Preparation of Nanocrystalline MgH2 by Solid-Gas Reaction Milling in Hydrogen

摘要:

采用固-气反应球磨制备纳米晶MgH2粉末，测定纯镁粉在球磨过程中的吸氢动力学曲线。借助X射线衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）等分析手段，研究Mg-H2反应球磨过程中的相结构与粉末形貌演变规律。结果表明，在机械球磨驱动作用下，Mg的吸氢过程可分为“缓慢-快速-饱和”3个阶段，其相组成分别对应 “Mg(H)- Mg(H)+ MgH2-MgH2”。在0.5 MPa氢气压条件下，球磨21 h可使Mg完全氢化，获得粉末粒度1~3 μm、晶粒尺寸10 nm左右的纳米晶MgH2粉末，其实际氢含量高达7.03%（质量分数，下同）。

Abstract:

The method of solid-gas reaction milling was used to prepare nanocrystalline MgH2 powder. The hydrogen absorption kinetics of pure Mg during reaction milling was measured, and the powder morphology and phase structure evolution were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), respectively. It was found, upon milling in hydrogen, the process of Mg absorbing hydrogen presented a three-stages, i.e., slow-fast-saturation, whose phase compositions corresponded to Mg(H), Mg(H)+MgH2 and MgH2, respectively. By milling for 21 h under H2 atmosphere at 0.5 MPa, Mg could be fully hydrided into nanocrystalline MgH2 powder with an average particle size of 1~3 μm and crystallite grain size of about 10 nm, respectively. Such nanocrystalline MgH2 presented the hydrogen capacity as high as 7.03 wt%.