Wu Zhu

Influences of Partial Substitution of VFe Alloys for Cr on Structure and Hydrogen Storage Performances of TiCr1.8 Alloy

Abstract Influences of partial substitution of VFe alloys for Cr on structure and hydrogen storage performances of TiCr 1.8 alloy were studied by XRD, PCT and TG-DSC methods. Results show that phase composition gradually changes from single Laves phase to BCC phase. Crystal cell parameters are enlarged by increasing of VFe content in alloys. The maximum hydrogen capacity increases also with the increase of VFe content in alloys. It is up to 5.2/a. f. u. (the unit of a.f.u. means the ratio of the number of absorbed hydrogen atoms to alloys formula unit) corresponding to 3.4% in mass. The reversible hydrogen storage capacity increases first, but then decreases with the increase of VFe content in alloys. There are two kinds of positions with different combining energy for hydrogen storage in TiCr 1.2 (VFe) 0.6 alloy with BCC phase.

Kinetics of Hydrogen Absorption for Ti33V20Cr47 Alloy Powder

Abstract Influences of temperature, initial pressure and particle size on the hydriding reaction kinetics of Ti33V20Cr47 alloy powder was analyzed and discussed. It is found that the rate-controlling step of the hydriding processes is hydrogen diffusion with the activation energy of 25.7±0.8 kJ/mol. The reaction rate can be accelerated with the increase of temperature. The Ti33V20Cr47 alloy can finish hydrogen absorption faster under the initial pressure 1.5 MPa and 2.5 MPa than under the initial pressure 3.5 MPa because it has two plateaus. The reaction rate can also be accelerated with the increase of particle size. The possible reason could be related to the fact that the large particle size is adverse for the dissipation of reaction heat, thus leading to the rise of the alloy temperature.