Study on the Combustion Synthesis for Producing High Performance Hydrogen Absorbing Alloy

燃烧合成生产高性能吸氢合金的研究

• 批准号: 09450276
• 负责人: YAGI Jun-ichiro
• 金额: $ 8.45万
• 依托单位: Tohoku university
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450276/
• 关键词: Combustion Synthesis; Metal Hydride; Intermetallics; Reaction mechanism; Activation Process; Intermediate Product; 水素吸蔵合金; Mg_2Ni; DSC; TG; X線回折; 高温顕微鏡; 共晶温度; Combustion Synthesis; Metal Hydride; Intermetallics; Reaction mechanism; Activation Process; Intermediate Product; 水素吸蔵合金; Mg_2Ni; DSC; TG; X線回折; 高温顕微鏡; 共晶温度

The intermetallic compound of Mg_2Ni has been regarded as one of the most attractive hydrogen storage alloys because of very high hydrogen absorbing quantity of 3.6 mass %. However, conventional production system of Mg_2Ni has two less productive processes which are several times remeltings and activation process. To overcome these problems, combustion synthesis has been studied for producing directly Mg_2NiH_4 in this study. The result shows the successful synthesis of Mg_2zNiH_4, proposing combustion synthesis as one of the promising process. For realizing practical production of Mg_2NiH_4 in hydriding combustion synthesis, rates of hydriding and dehydriding must be studied. For the first attempt for this purpose, reaction mechanism has been studied in hydriding and dehydriding combustion synthesis of Mg_2NiH_4, by using PTC apparatus, DSC and in situ X-ray diffractometer. Nine reactions in this process were obtained for two cycles of heating and cooling in hydrogen pressure of 1.0 MPa as follows.In the first cycle ; (1) Mg+H_2*MgH_2(partially), (2) MgH_2*Mg+H_2, (3) 2Mg+Ni-Mg_2Ni, in the heating period. and (4) Mg_2Ni+2H_2*Mg_2NiH_4(HT), partially (5) Mg_2NiH_4(HT)*Mg_2NiH_4(LT), in the cooling period. In the second cycle ; (6) Mg_2NiH_4(LT)*MMg_2NiH_4(HT), (7) Mg_2NiH_4(HT)*Mg_2Ni+2H_2, in the heating period. and (8) Mg_2Ni+2H_2*Mg_2NiH_4 (HT) partially, (9) Mg2NiH4 T)*Mg_2NiH_4(LT), in the cooling period.The X-ray diffraction intensity of Mg_2NiH, after the second cycle of hydriding is 6 times of that after the first cycle of hydriding, although only one single phase of Mg_2Ni exists at 823K before the hydriding either the first cycle or the second cycle.

MG_2NI的金属间化合物被认为是最具吸引力的氢储存合金之一，因为吸收量很高的3.6质量％％。但是，MG_2NI的常规生产系统具有两个较低的生产过程，这些过程是重复和激活过程的几倍。为了克服这些问题，已经研究了燃烧合成以直接产生MG_2NIH_4。结果显示了MG_2ZNIH_4的成功合成，提出燃烧合成为有希望的过程之一。为了实现水合燃烧合成中MG_2NIH_4的实际生产，必须研究水合物和脱水的速率。为此，为此目的，已通过使用PTC设备，DSC和原位X射线衍射仪，研究了MG_2NIH_4的水合和脱水燃烧合成中的反应机制。在此过程中，在第一个循环中获得了1.0 MPa的氢压力中的两个加热和冷却的循环的九个反应。 （1）Mg+H_2*MGH_2（部分），（2）MGH_2*mg+H_2，（3）2mg+Ni-Mg_2ni，在加热期内。 （4）MG_2NI+2H_2*MG_2NIH_4（HT），部分（5）MG_2NIH_4（HT）*MG_2NIH_4（LT），在冷却期间。在第二个周期中； （6）MG_2NIH_4（LT）*MMG_2NIH_4（HT），（7）MG_2NIH_4（HT）*MG_2NI+2H_2，在加热期内。和（8）mg_2ni+2h_2*mg_2nih_4（ht），（9）mg2nih4 t）*mg_2nih_4（lt），在冷却期内。X射线射线衍射强度是mg_2nih的X射线衍射强度，在液压下的第二个周期中，MG_2NIH的第二个阶段是一个单一循环，即MINS的一个单元3次。在水合之前，第一个周期或第二个周期。