Hydrogenation Kinetics and Physical Characteristics of Ni, Ti, and Fe2O3-Added Mg by Reactive Mechanical Grinding

Abstract

Abstract: Samples with the compositions of 80 wt% Mg-14 wt% Ni-6 wt% Fe2O3, 80 wt% Mg-14 wt% Ni- 6 wt% Ti and 80 wt% Mg-14 wt% Ni-3 wt% Fe2O3-3 wt% Ti (called Mg-14Ni-6Fe2O3, Mg-14Ni-6Ti and Mg-14Ni-3Fe2O3-3Ti, respectively) were prepared by reactive mechanical grinding. Their hydriding and dehydriding rates were then measured at the first cycle, and the specific BET surface areas, grain sizes, and strains of the samples were analyzed. The quantities of hydrogen absorbed and desorbed for x min are indicated as Ha (x min) and Hd (x min), respectively. The values of Ha (10 min) and Hd (30 min) for Mg-14Ni-6Ti were the largest, followed in order by Mg-14Ni-3Fe2O3-3Ti and Mg-14Ni-6Fe2O3. The particles on the surface of the Mg-14Ni-6Ti were the finest, followed in order by Mg-14Ni-3Fe2O3-3Ti and Mg-14Ni-6Fe2O3. Mg-14Ni-6Ti had the smallest grain size, followed in order by Mg-14Ni-3Fe2O3-3Ti and Mg-14Ni-6Fe2O3. The inverse dependence of the values of Ha (10 min) and Hd (30 min) on the grain size indicates that the values of Ha (10 min) and Hd (30 min) increase as the grain size decreases and thus the grain boundary area increases.