Electrodeposition of Ni, Fe and Ni-Fe alloys on a 316 stainless steel surface in a fluorborate bath

Electrodeposition processes of Ni, Fe and Ni-Fe alloys on 316 stainless steel surfaces in fluorborate baths were studied using conventional electrochemical techniques and atomic force microscopy. The results showed that these processes occurred under mass transfer control, associated with nucleation and growth process. Cathodic current-time transients indicated that the nucleation and growth of Ni-Fe alloy was different from that of the single metal (Ni or Fe). For one, two nucleation and growth processes occurred during Ni-Fe alloy codeposition. Also, there was a nucleation and growth process of Ni-Fe alloy on Ni-Fe clusters, due to a change of the Ni-Fe alloy composition and phase. Homogeneous Ni-Fe alloy deposits could be obtained by pulse potential plating. AFM images of Ni, Fe and Ni-Fe deposits prepared by pulse potential plating revealed the following results: (1) the growth rate of Ni nuclei was faster in parallel than in perpendicular to the 316 electrode surface; (2) for Fe nuclei, the preferential growth direction was perpendicular to the 316 electrode surface; and (3) for Ni-Fe nuclei, there was no preferential growth direction and uniformly hemispherical Ni-Fe clusters were obtained. (C) 2009 Elsevier Ltd. All rights reserved.