The electrodeposition of Ni-Cu and Ni-Cu-P from aspartate-based baths

Abstract

The electrodeposition of Ni-Cu and Ni-Cu-P was performed over steel electrodes using baths containing aspartate as a complexing agent for the metallic cations. Through the rotating disk electrode technique and the measurement of the deposition potentials, it was found that the electrodeposition is controlled by activation at current densities (jdep) equal or lower than 10 mA cm−2 and suffers limitations on diffusion for jdep>10 mA cm−2. The hydrogen evolution reaction during the electrodeposition was more intense over Ni-Cu-P films leading to a lower efficiency compared to the Ni-Cu films. The composition of the amount of Cu in the Ni-Cu films varied from 13.7% to 21.5%, while the amount of Cu in the Ni-Cu-P films varied from 24.4% to 43.1%. The P incorporation was low, varying from 1.2% to 2.8%. For the Ni-Cu films, globular, dendritic, and smooth films were obtained depending on the deposition control and the efficiency. The Ni-Cu-P presented dendritic and smooth morphology depending on the efficiency.