金属化合物の粉末冶金と諸物性 微小重力を利用した水素吸蔵合金の作製

Abstract

Ti-Fe alloy is one of the most useful materials for hydrogen storage alloy. In order to improve the absorption-desorption for hydrogen, however, it requires homogeneous structure and microscopically large surface. The effect of microgravity which suppresses the convection of constituents in molten alloy, against nucleation and crystal growth in solution has attracted attention. A preliminary investigation for synthesis of homogeneous Ti-Fe alloy has been examined. Furthermore, fundamental research concerning in the properties of hydrogen storing alloy and crystal structure has been performed. On the relation between hydrogen pressure and concentration of stored hydrogen shown in P-C-T (hydrogen pressure-concentration of stored hydrogen-temperature) curve, large hysteresis and rapid absorption-desorption was observed on the Ti-Fe sample produced at 1050°C under normal gravity. But Ti-Fe alloy produced at 1280°C under microgravity, hydrogen charge or discharge pressure decreased and the gradient of the curve become plateau at 0.5-1.0 hydrogen concentration. In case of the sample produced under normal gravity, heterogeneous composition and dense structure was observed, while homogeneous composition and porous structure was obtained easily in the sample produced under microgravity. Furthermore, powdering phenomenon after cycle of absorption-desorption of hydrogen was not occurred around porous structure produced under both normal gravity and microgravity conditions.