Voltammetric Analysis of Phase Composition of Zn-Ni Alloy Thin Films Electrodeposited from Weak Alkaline Polyligand Electrolyte

Abstract

The phase composition of Zn-Ni alloy films electrodeposited from a slightly alkaline polyligand electrolyte was analyzed by anodic voltammetry method. The mechanism of films anodic dissolution in alkaline ammonia-glycinate solution not containing metal ions is proposed. The main peaks correspond to the zinc dissolution from -phase and from -phase of the initial film and the nickel-enriched phase formed during the film dissolution. The nickel content in the nickel-enriched phase is determined, as well as nickel and phase content in the original film, depending on the ratio of metal ion concentrations in the electrolyte at various ratios of glycine and ammonia concentration. It is shown that films in a wide range of these ratios ([Ni 2+ ]:[Zn 2+ ]  (2-5):1 and [Gly-]:[NH3(NH4 +)]  (2-9):5) contain mainly -phase with nickel content in the range of 15.8-18.2%.

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

“…These CVs start from stationary potential of platinum (around 0 B, clearer seen in Panel b), in the cathode direction. As better shown in [43], as the cathodic polarization increases, the reduction of Pt oxides and the dissolved oxygen takes place on the Pt electrode surface. After that, at potentials ≈‐0,75 V, nickel and then nickel‐enriched phase are obtained, and then at −1.15 V zinc‐enriched alloy begins to deposit simultaneously with intensive hydrogen reduction.…”

“…Nickel‐enriched phase dissolves during the next peak C. This phase which did not exist in the original film was formed as a result of phase transition and zinc dissolution from the alloy at the range of potentials of previous peaks [41, 43, 63]. With coating thickness increase, this peak shifts significantly toward more negative potentials.…”

“…In our previous studies [43, 44], the examples of quantitative analysis of anodic voltammograms of Zn−Ni alloy films dissolution in a polyligand ammonia‐glycinate electrolyte not containing ions of deposited metals were presented. However, in these studies, the thickness of the dissolved films was limited by 300 nm.…”

Establishing the patterns in the formation of oxide films on the alloy Ti6Al4V in carbonic acid solutions

“…The oxide layer is enriched with oxygen from the side of the electrolyte, which is a very common case at anodic polarization. This situation is observed when active anodes are dissolved, for example, copper in acid [22] or nickel in alkaline [23] electrolytes. Another case is the formation of oxide layers during anodic polarization of steels in [24, 25] and copper [26] in alkaline solutions.…”

Establishing the patterns in anode behavior of copper in phosphoric acid solutions when adding alcohols

“…Also desirable is to perform polishing for the pretreatment of articles' surface in the case of applying multilayer coatings or coating the products with a complex composition [3][4][5][6].…”