超细纯镁及镁钛粉体的制备及储氢性能

采用直流电弧等离子体方法制备超细纯Mg及Mg-Ti粉体。运用X射线衍射（XRD）,透射电子显微镜（TEM）,压力成分温度（PCT）方法和TG/DTA技术研究粉体吸放氢前后的相组成、微观结构和吸放氢性能。结果表明,大部分超细Mg和Mg-Ti颗粒呈六角形,颗粒大小在50700nm范围内。根据范特霍夫方程计算由PCT曲线获得的吸氢平台压力,Mg-Ti粉的氢化焓约为67kJ/mol H2,显著高于纯镁粉的氢化焓78.6kJ/mol H2。TG/DTA分析表明,氢化后Mg-Ti粉的放氢起始温度为386°C,低于氢化纯镁粉的放氢温度（423°C）。通过电弧蒸发法直接向Mg中添加Ti而获得的Mg-Ti超细粉体可以显著改善镁的储氢热力学性能。

Preparation and hydrogen storage properties of ultrafine pure Mg and Mg-Ti particles

The ultrafine pure Mg and Mg-Ti particles were prepared through a direct current (DC) arc plasma method. The X-ray diffraction (XRD), transmission electron microscopy (TEM), pressure-composition-temperature (PCT) method and TG/DTA techniques were used to study the phase components, microstructure and hydrogen sorption properties of the powders before and after hydrogen absorption. It is revealed that most of the ultrafine Mg and Mg-Ti particles are hexagonal in shape with particle size in the range of 50-700 nm. According to the Van’t Hoff equation, the hydrogenation enthalpy of Mg-Ti powders is determined to be about -67 kJ/mol H2 based on the PCT curves of hydrogen absorption plateau pressures. This value is much higher than -78.6 kJ/mol H2 for pure Mg powders. TG/DTA analyses show that the onset dehydriding temperature of hydrogenated Mg-Ti powders is 386 °C, which is significantly lower than that of the hydrogenated Mg (423 °C). The results prove that the addition of Ti into Mg through arc evaporation method can improve the thermodynamic properties of Mg for hydrogen storage.