La原料对LaMg17Ni储氢合金性能影响研究

为降低LaMg_(17)Ni储氢合金的成本并解决原材料La不稳定导致的安全问题,采用了La-H粉和La-Mg合金粉两种性能稳定且成本较低的原料替代La粉,利用机械合金化法制备了不同原料的LaMg_(17)Ni储氢合金,并对比两种不同原料制备合金的性能,探究性能差异的原因。采用比表面仪检测合金比表面积变化,用扫描电子显微镜(SEM)表征合金微观形貌,X射线衍射(XRD)表征合金制备前后和吸放氢前后相结构变化,利用高温高压气体吸附仪测试合金的吸放氢曲线、储氢量以及储氢速度。结果表明,以La-H粉为原料制备的合金储氢量达到4.58%,在3MPa氢气压力、温度573K以下,储氢速度为90s内达到饱和储氢量的90%以上,而以La-Mg合金粉原料制备的合金储氢量达到4.43%,在3MPa氢气压力、温度573K以下,储氢速度为120s内达到饱和储氢量的90%以上。由于La-H粉的高脆性使其在机械合金化过程中产生了更高的比表面活性以及内部原有LaH3相的直接催化作用,因此以La-H粉为原料制备的LaMg_(17)Ni合金储氢性能优于以La-Mg合金粉为原料制备的LaMg_(17)Ni合金。

Influence of lanthanum raw materials on Hydrogen Storage Properties of LaMg17Ni

The alloy LaMg17Ni was prepared by mechanical alloying, The properties of the alloys prepared by two different La raw materials were compared. The alloy prepared by La-H possesses hydrogen storage capacity of 4.58 mass%, Under 3 Mpa hydrogen pressure, the alloy can absorb more than 90% of its full hydrogen capacity in less than 90s at 573 K. The alloy prepared by La-Mg possesses hydrogen storage capacity of 4.43 mass%, Under 3 Mpa hydrogen pressure, the alloy can absorb more than 90% of its full hydrogen capacity in less than 120s at 573 K. By Specific surface area detection, X-ray diffraction and SEM, It was found that the high specific surface activity after mechanical alloying and the LaH3 and Mg2NiH4 phase formed in the process of hydrogen storage are the main reasons for improving the hydrogen storage performance of LaMg17Ni alloy.