Experimental investigation of the swelling/shrinkage of a hydride bed in a cell during hydrogen absorption/desorption cycles

A novel capacitive device for the study of volumetric expansion of hydride powders

“…For this purpose, we used two batches of unhydrided LaNi 5 (99.9% REO, Alfa Aesar), one just crushed to small but still macroscopic grain sizes, and the other pulverized to fine grains by previous hydrogenation cycling. In order to check the universality of this calibration, we included also measurements on two other metallic alloys with high capacity to absorb hydrogen: FeTi [10] and the composite TiV 0.8 Cr 1.8 þHf 7 Ni 10 [22,28,29]. Different grain sizes result in different porosities [30,31], and by mixing different grain sizes we can alter the packing and reduce the porosity [32].…”

“…Neutron irradiation (radiography and tomography) of a chamber with a hydride reveal the changes of volume, porosity and density along the process of charge and discharge with hydrogen [19e21]. Charlas et al [22] present an experimental apparatus for the study of the macroscopic volumetric changes of the hydride of a TieCreV þ ZreNi alloy. This apparatus has rigid cylindrical walls and the sample is confined and slightly compressed by a spring attached to a vertically moving piston that allows the measurement of the volume occupied by the sample.…”

A tool for modelling the breathing of hydride powder in its container while cyclically absorbing and desorbing hydrogen

“…In this model, Hu et al are using a phenomenological Shima and Oyane model. This model is usually employed to model porous and ductile materials allowing tensile stress such as sintered granular material [32,33] whereas the intermetallic hydride powder medium are generally very porous powders [19,20] and are made of hard, tough and fragile grains. Besides, nothing is really detailed on how Hu et al calibrate the model parameters.…”

“…Before this, some experimental results about the breathing of a TieCreV hydride [19] are recalled. Next, the principle of the Discrete Element Method is exposed.…”

MgH 2 thin films deposited by one-step reactive plasma sputtering

“…In such a case, storage tanks are usually filled with additivated, micro/nanostructured materials associated to an internal heat transfer media (such as metallic foam [6] or expanded graphite [7]) to prevent the degraded performance of hydride powders due to both hydrogen and heat diffusion limited processes. However, decrepitation and intergranular segregation associated to the repeated swelling and shrinkage of the hydrides upon absorption and desorption of hydrogen can be responsible for reduced cyclability of powder-filled tanks [8]. Such mechanical issues can be avoided by confinement of the storage material in porous matrices or by shaping it as thin films.…”