Hydrogenation and Dehydrogenation Properties of Mg-Cu, Mg-Al Eutectic Alloy
- PDF / 300,268 Bytes
- 10 Pages / 612 x 792 pts (letter) Page_size
- 28 Downloads / 234 Views
1216-W08-22
Hydrogenation and dehydrogenation properties of Mg-Al and Mg-Cu eutectic alloy Ho Shin1, Yuma Eto1, Hiroyuki T. Takeshita1 and Koji Tanaka2 1 Faculty of chemistry, Materials and Bioengineering, Kansai University 3-3-35 Yamate-cho, Suita, Osaka, Japan 2 Research institute for Ubiquitous Energy Devices, AIST Kansai, National institute if Advanced 1-8-31 Midorigaoka, Ikeda, Osaka, Japan ABSTRACT Mg has 7.6 mass% of high gravimetric hydrogen density, an abundance of resources and inexpensive price compared with other functional materials. Owing to these merits, it has been the major subject of hydrogen storage study. However, it is unsuitable for practical application due to thermodynamic stability and slow kinetics of Mg hydride. Therefore, many ways such as fabrication of nanocrystalline or addition of catalyst have been proposed to solve the problems of Mg hydride system. Copper and aluminum are inexpensive and can obtain easily as well as Mg. Each eutectic alloy could be produced by sintering process and observed improvement of reaction with hydrogen. Mg2Cu laminate, one phase of Mg-Cu eutectic alloy, could also be produced by cold-rolling process, and it showed reversible reaction with hydrogen, at this study. INTRODUCTION In the materials for hydrogen storage, Mg has been studied the one mostly due to its high theoretical gravimetric hydrogen density (7.6mass %) and inexpensive price compared with other hydrogen storage materials (e.g. Ni, Ti, V, Cr and La etc.) [1,2]. However, Mg needs high temperature for hydrogen absorption and desorption because of its thermodynamic stability and also it has too slow reaction rate with hydrogen[3,4]. Therefore, many scientists have been researched to improve these drawbacks of Mg. There are large numbers of betterment methods and these can be broadly classified to alloying by addition of other elements or catalyst and mechanical processing as ball milling or thin film, etc[5]. For example, since Reilly et al. have reported that Ni adds to Mg at 300psia of hydrogen pressure for catalyst function firstly[6], occurring reaction of hydrogen absorption and desorption at lower temperature than only Mg phase, Mg2NiH4 alloy production have been developed by various processes such as chemical synthetic, isothermal evaporation and combustion synthesis method[7-9]. In this study, we paid attention to Mg-Al and Mg-Cu alloy systems for improving of hydrogenation properties. Above mentioned Al and Cu are inexpensive comparatively and obtainable materials easily as well as Mg. Thus, they have been researched previously because its some alloy phases, as Mg17Al12, Mg2Al3 and Mg2Cu, react with hydrogen reversibly having storage capacity of 2.40, 2.04 and 2.69wt%, respectively[10,11]. Slow hydrogen diffusion rate in Mg[12] is main interruption in Mg hydride system for practical application. Therefore, if it is given many passageways which hydrogen is able to move in alloy, then it can be expected fact that hydriding and dehydriding occur without difficulties by expansion of diffusio
Data Loading...
