MEASUREMENT AND MODELING OF HYDRIDING AND DEHYDRIDING KINETICS

The rates of hydriding and dehydriding were measured for LaNi5Hx under isothermal and isobaric conditions. Obtained data of hydriding rates indicated that the rate controlling step was the nucleation and growth process of the hydride phase and then changed to hydrogen diffusion t hrough the hydride phase at the later stage. On the other hand, for th e desorption of hydrogen, the rate controlling step was only the homog eneous chemical reaction of the hydride phase. Theoretical rate equati ons were derived on the basis of the kinetic model of hydriding and de hydriding reaction proposed in this study. A satisfactory agreement be tween the theoretical and experimental results was obtained. (C) 1998 Elsevier Science S.A. All rights reserved.