Passivation and reactivation of Ti25V35Cr40 hydrides by cycling with impure hydrogen gas

Cyclic hydrogenation stability of γ-hydrides for Ti25V35Cr40 alloys doped with carbon

“…Some reaction conditions resulted in a significant shift in T s from room temperature for an activated specimen to 170 C for a poisoned specimen that was sealed with impurities at the surface. These conditions have been discussed in a previous publication [22].…”

“…A modified automatic Sievert's apparatus equipped with a TPD spectrometer was constructed for the cyclic hydrogenation test [22,24]. High-purity (99.9999%) hydrogen gas was used.…”

“…TPD spectra were used to examine the contributions, if any, of extrinsic factors [22]. The TPD spectra for the activated and cycled Ti 25 V 35 Cr 40 , which were charged to the b-hydride phase with a hydrogen content of 0.75 H/M and a hydrogen pressure of 0.02 MPa, are presented in Fig.…”

“…Therefore, the aim of this study was to investigate the cyclic hydrogenation behavior of the annealed Ti 25 An automatic Sievert's apparatus equipped with a temperatureprogrammed desorption (TPD) spectrometer was constructed to study the stability of annealed Ti 25 V 35 Cr 40 C x (x ¼ 0 and 0.1) alloys under cyclic hydrogenation. A TPD technique was employed to examine whether the cycled specimen was degraded extrinsically via surface contamination by impurities in the H 2 gas [14,15,22]. Additional measurements, including hydrogenation kinetics, PeC isotherm curves, maximum hydrogenation capacities, and the changes in phase structure for the specimens, were also included to determine the hydrogenation degradation behaviors of the specimens.…”

Performance Improvement of V–Fe–Cr–Ti Solid State Hydrogen Storage Materials in Impure Hydrogen Gas

“…AB-, AB 2 - and AB 5 -type alloys, such as TiFe, ZrV 2 , and LaNi 5 as well as V–Ti-based solid solution alloys have been studied with respect to their behavior upon cycling in impure hydrogen. − ,− Two main conclusions can be drawn from these studies: (1) the tolerance of most metal hydrides toward critical impurities such as oxygen is too low for most technical applications, and (2) LaNi 5 and its related compounds exhibit the highest tolerance toward impurities. The improved tolerance of LaNi 5 toward impurities is linked to its surface properties.…”