Electrodeposition of Re-Ni alloys from aqueous solutions with organic additives

In this study, Re-Ni alloys with high Re content were electrodeposited on copper substrates from aqueous solutions containing additives with a combination of vanillin, sodium lauryl sulfate and gelatin. The bath additives were found to have a significant effect on the chemical composition, surface morphology and cracking pattern. The morphology of the alloy was changed from uniformly smooth without additives to relatively coarse-grained with three additives. The deposition rate and crack density decreased when additives were added to a bath containing 34 mM ReO₄ ⁻, 124 mM Ni^2 + and 343 mM [Cit]^3 −. Almost pure Re films were formed at low Ni^2 + concentration of 30–50 mM due to the effect of additives; however, the deposited film was thin. A thin layer of Re oxide, a new Re-O-C-complex state and some organic residues from additives were formed at the surface of the Re film. Both the Re-rich alloy and the Re film were found to have an amorphous structure.