La-Ni-H metal hydride system aging effects identification

One of the most commonly used materials for sorption compression in space applications is based on the La-Ni-H system. The degradation of the material properties and, therefore, the system lifetime is of great importance for the final success of a potential space mission. Considering that satellites and other equipment that have to operate in space are expected to be fully functional for more than 10 years, in this work, an accelerated aging method is designed and carried out to predict the La-Ni-H system properties after 12 years under specific operating conditions. For this test, several specimens of fully hydrogenated LaNi₅ are exposed to specific hydrogen pressures (i.e., 20, 35, 58 and 96 bar) at different temperatures (i.e., 50, 90, 130 and 160 °C) for a duration of 90 days. Sievert's type apparatus, synchrotron radiation powder X-ray diffraction (SR-PXD), quasi-elastic neutron scattering (QENS), scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS) methods are used to investigate the material aging and its impact on the material chemical and microstructural properties.