Formation of Mg-Ni hydrogen absorption alloy film by molten salts electrolysis

A Magnesium-Nickel hydrogen absorption alloy, Mg2Ni, was produced as a film by molten salts electrolysis and diffusion process. Magnesium was electrod eposited on a nickel substrate from a 25 mol % NaCl - 5 mol % KCI -70 mol % CaCl2 mixture as a supporting electrolyte, and additionally 10 mol % MgCl2 with respect to the supporting electrolyte as magnesium-ion source. The el ectrodeposition was conducted at 873 similar to 1073 K and with cathodic cu rrent densities between 0.02 similar to 0.10 A cm(-2) for 3.6 similar to 18 Its. After the electrolysis, the specimens were subjected to X-ray diffrac tion and EPMA line analysis to identify the phase of compounds and to measu re the thickness of the film. As a result, only hydrogen absorption alloy f ilms, Mg2Ni, were obtained with 20 mu m and 27 mu m thickness from electrod eposition with 0.10 A cm(-2) for 3.6 ks at 1023 K and with 0.02 A cm(-2) fo r 18 ks at 873 K! respectively. At 1073 K, the intermetallic compound MgNi2 was also detected between the Mg2Ni layer and the nickel substrate. These specimens were subjected to hydrogen absorption tests in 30 mass % KOH solu tion at 298 K. It was confirmed that these specimens absorbed hydrogen.