Stability of ZrCo and ZrNi to heat cycles in hydrogen atmosphere
Fusion Technology, 28 (1995) 1437-1442
Kuniaki Watanabea, Masanori Haraa, Masao Matsuyamaa, Isao Kanesakab, Toshiaki Kabutomoric
a Hydrogen Isotope Research Center,
b Department of Chemistry, Faculty of Science, Toyama University, Gofuku 3190, Toyama 930, Japan
c Japan Steel Works, Muroran Research Laboratory, 4 Chatu-Machi, Muroran 051, Japan
Abstract
The stability of ZrNi and ZrCo to heat cycles in hydrogen atmosphere was studied through changes in absorption-desorption characteristics and in crystallographic structures. ZrCo easily lost its absorption-desorption capacity of hydrogen below 30 heat cycles between room temperature and a given temperature in a range of 400〜600℃. X-ray diffraction analysis showed that ZrCoH3 initially formed decomposed to ZrH2 + ZrCo2. On the other hand, ZrNi was more durable than ZrCo to the similar heat cycles. But, it was found that the absorption-desorption characteristics was degraded by heat cycles over 500. The X-ray analysis showed that ZrNi also disproportionated to ZrH2 and ZrNi3. The difference in the stabilities between the two materials appears to be due to the difference in crystallographic nature upon formation of the respective hydrides.