Influence of voltammetric parameters on Zn–Ni alloy deposition under potentiodynamic conditions

Abstract

The phase composition of Zn-Ni alloys electrodeposited from acetate-chloride plating solutions containing Zn ?2 and Ni ?2 ions at ratio of 1-12.8 at 50°C was investigated by the potentiodynamic stripping method. Two anodic current density (i a ) peaks emerged in potentiodynamic stripping curves (PDC) at E \ 0.0 V and E [ 0.0 V (vs. Ag/AgCl/KCl sat ), that were attributed to oxidation of certain phases of the Zn-Ni alloy. The ratio of these phases in deposited Zn-Ni alloys under potentiodynamic conditions was affected by the potential sweep rate (m) and maximum cathodic current density (i c ) The ratio of Zn and Ni in certain phases of Zn-Ni alloy was determined by the partial potentiodynamic stripping technique. Experimental data show that Zn-Ni alloy, containing 6.5 at.% Zn and 93.5 at.% Ni and dissolved in i a peak H (E [ 0.0 V), provides the black coloration of the Zn-Ni alloy.

Quantitative Analysis of Chemical and Phase Composition of Zn−Ni Alloy Coating by Potentiodynamic Stripping

“…%. This suggests that in the last peak D of this voltammogram matrix nickel dissolves, which was not dissolved with nickel‐enriched phase in the previous peak, as in chlorammiac electrolytes [28], pyrophosphate [55–57, 76], sulfate [18, 32, 46], acetate [53], chloride [13, 62], citrate [2] electrolytes. It should be noted that the dense nickel films dissolve in this electrolyte at potential more positive than +0.3 V.…”

“…Section 3 starts from stripping voltammetry in the electrolyte for the alloy deposition . For such qualitative analysis the anode response of CV is used in ammonia electrolytes [10, 18, 24, 33, 45], sulphate [12, 17, 26, 46, 47–49], and chloride [13, 15, 21, 23, 34,50,51] electrolytes, in electrolytes with sulfamic acid [52], acetates [27, 53, 54], as well as in complex electrolytes based on pyrophosphate [55–57], citrate [2], amines [58], glycine and ammonia [59]. After general characterization of the coating (subsection 3.2) and choosing optimal conditions for alloy dissolution (Subsection 3.3) we present the results of qualitative (Subsection 3.4) and quantitative (Subsection 3.5) analysis by stripping voltammetry in alkaline ammonia‐glycinate electrolyte, free from Ni 2+ i ions.…”