Mg-Ni-HおよびMg-Ni-Al-H合金の水素昇温脱離特性に及ぼす酸化の影響
1998 年 62 巻 1 号 p. 111-116
詳細
1998 年 62 巻 1 号 p. 111-116
Thermal desorption spectrometry (TDS) was carried out for hydrogenated samples of Mg0.9Ni0.1, Mg0.77Ni0.23 and Mg0.78Ni0.20Al0.02 in the temperature range of 298 to 723 K. Two kinds of samples were prepared for each alloy: samples not exposed or exposed to air after hydrogenation. Two peaks overlapped in each TDS curve. The low temperature peak is caused by the decomposition of Mg2Ni or Mg0.73Ni0.26Al0.01 hydride and the high temperature peak is caused by the decomposition of Mg hydride. The peak-shift of both peaks after the air-exposure was less than 50 K for the hydrogenated Mg0.77Ni0.23 and Mg0.78Ni0.20Al0.02, while the peak-shift of the hydrogenated Mg0.9Ni0.1 was very large, especially for the high temperature peak, i.e., more than 100 K. The hydrides of Mg2Ni and Mg0.73Ni0.26Al0.01 phases kept their activity for hydrogen desorption even after the air-exposure. It is considered that the hydride surface of primary Mg crystals is easily oxidized and becomes inactive, while Mg hydride in the eutectic is densely surrounded by Mg2Ni hydride and sintering process between both phases during hydriding-dehydriding treatment occurs, and hydrogen in the Mg hydride desorbs through the Mg2Ni or Mg0.73Ni0.26Al0.01 phase.
