Formation of Mg-Ni Hydrogen Absorption Alloy Film by Molten Salts Electrolysis

抄録

A Magnesium-Nickel hydrogen absorption alloy, Mg₂Ni, was produced as a film by molten salts electrolysis and diffusion process. Magnesium was electrodeposited on a nickel substrate from a 25 mol % NaCl - 5 mol % KC1 -70 mol % CaCl₂ mixture as a supporting electrolyte, and additionally 10 mol % MgCl₂ with respect to the supporting electrolyte as magnesium-ion source. The electrodeposition was conducted at 873∼1073 K and with cathodic current densities between 0.02∼0.10 A cm⁻² for 3.6∼18 ks. After the electrolysis, the specimens were subjected to X-ray diffraction and EPMA line analysis to identify the phase of compounds and to measure the thickness of the film. As a result, only hydrogen absorption alloy films, Mg₂Ni, were obtained with 20 µm and 27 µm thickness from electrodeposition with 0.10 A cm⁻² for 3.6 ks at 1023 K and with 0.02 A cm⁻² for 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 solution at 298 K. It was confirmed that these specimens absorbed hydrogen.