Hydrogen absorption behavior of Zr-based getter materials with PdAg coating against gaseous impurities

In this work, PdAg coating has been deposited on different Zr-based Lave phase alloys, including ZrV2, Zr0.9Ti0.1V2 and Zr57V36Fe7, by the electroless plating technique. It is attempted to illustrate the role of PdAg coating on hydrogenation performance of Zr-based alloys against gaseous impurities. X-ray diffraction and scanning electron microscope (SEM) observations along with energy disperse spectroscopy (EDS) give evidences that the PdAg coating has been uniformly deposited on the surface of experimental alloys. Activation behavior and hydrogenation kinetics in pure H2 and mixture gases (H2 containing 1 vol.% air) are evaluated by using a Sieverts-type apparatus. The PdAg coating accelerates the hydrogenation kinetics and slightly decreases the hydrogen storage capacity of experimental Zr-based AB2 alloys. The poisoning effect of air gaseous impurities mainly deteriorates the hydrogen absorption capacity of experimental Zr-based alloys with PdAg coating at room temperature. The PdAg coated Zr0.9Ti0.1V2 preserves the fastest hydriding reaction rate at 303 K and 673 K among three experimental alloys. The slope value in the rapid absorbing stage (ka1) in mixture gases at each temperature of PdAg coated Zr-based AB2 alloys is quite higher than that of the corresponding bare alloy which indicates the uniform PdAg coating evidently improves the poison resistance capability of alloys in a wide temperature range. The PdAg coating does not fall off significantly from the surface after 6 times hydrogenation/dehydrogenation cycles.