Nanotechnology and nanomaterials

Analysis of nanoscale films of alloys of Cu-Sn-Ni-Zn system 
by stripping voltammetry
Maizelis A.
Department of Technical Electrochemistry, National Technical University «Kharkiv Polytechnic Institute», Kyrpychova str., 2, Kharkiv-61002, Ukraine. 
E-mail: a.maizelis@gmail.com

Binary alloys of the Cu-Sn-Ni-Zn system have a number of functional properties that determine a wide range of their use. The properties of alloys directly depend on their chemical and phase composition. Therefore, analysis of the composition of alloy coatings is of great importance both in the development of new methods for their deposition and existing processes. 
The method of stripping voltammetry is based on the analysis of peaks on anodic voltammograms of dissolution of thin alloy films deposited on an inert substrate under the conditions of analysis. It is a promising analysis method of their chemical and phase composition at the same time, especially in the analysis of nanoscale films that multilayer coatings consist of.
For the selective dissolution of the components of the binary alloys of the studied system, a number of electrolytes were tested. It is shown that anodic voltammograms of two-phase Sn-Zn alloy dissolution have 2 separate peaks of zinc and tin dissolution, as this alloy does not contain intermetallic compounds or solid solutions. 
Alloy phases of solid solutions of Cu in Ni, Zn in Ni, and Sn in Cu dissolve in one peak in all the studied electrolytes. There were selected the electrolytes for these alloys, in which the peak potential naturally changes with the composition of solid solution. It allows evaluating the chemical composition of the alloys out of the calibration curve. 
The deconvolution of the anodic voltammograms of the individual and double peaks makes it possible to separate the regions of potentials of various phases of Cu-Zn and Cu-Sn alloys dissolution in sulfate electrolytes. 
On the anode voltammogram of the Zn-Ni alloy film dissolution in ammonia-glycinate electrolyte, the dissolution peaks of free Zn, Zn from the δ- and γ-phases, as well as Ni-enriched residue and matrix nickel are recorded. Optimization of the electrolyte composition and dependence of potential scan rate on film thickness based on the example of Zn-Ni alloy films deposited for different times under the same conditions, significantly improved the accuracy of determining the chemical and phase composition of this alloy.