Electrochemical Deposition of Zinc-Based Composite Coatings Modified with Carbon Nanotubes from Alkaline Electrolyte
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SCALE AND NANOSTRUCTURED MATERIALS AND COATINGS
Electrochemical Deposition of Zinc-Based Composite Coatings Modified with Carbon Nanotubes from Alkaline Electrolyte V. N. Tseluikina,*, A. A. Striletsa, and A. V. Yakovleva aEngels
Technological Institute (Branch), Saratov State Technical University, Saratov oblast, Engel’s, 413100 Russia *e-mail: [email protected] Received January 14, 2020; revised January 17, 2020; accepted January 24, 2020
Abstract—Composite electrochemical coatings (CECs) based on zinc, modified with carbon nanotubes (CNTs) from an alkaline electrolyte in a pulsed electrolysis mode have been obtained. The microstructure and tribological properties of these CECs are investigated. It was found that the introduction of the dispersed CNT phase into the alkaline galvanizing electrolyte reduces the sliding friction coefficient of the forming coatings by a factor of 1.30–1.45. The corrosion–electrochemical behavior of zinc–CNT CECs in 0.5 M solution of H2SO4 has been described. DOI: 10.1134/S2070205120060246
INTRODUCTION An effective method for modifying metal surfaces is the application of composite electrochemical coatings (CECs). The principle of obtaining CECs is based on the codeposition of metals with dispersed particles of various nature from electrolyte suspensions [1, 2]. Galvanizing is one of the widely used processes in electroplating. According to [3], about half of world zinc production has the form of electrochemical coatings. CECs based on zinc and its alloys are used for corrosion protection of steel products with the improvement of their physical and mechanical properties [4–19]. The performance characteristics of CECs are largely determined by the nature of the dispersed phase. Zinc has an affinity for dispersed particles of various nature and easily forms composite coatings with them. Currently, zinc-based CECs modified with various nanomaterials are being actively studied [4–8, 12–19], since the introduction of nanosized particles into a metal matrix makes it possible to obtain structural materials that are superior in functional properties to coarse-grained analogs. One of the promising nanomaterials are carbon nanotubes (CNTs), which are cylindrical molecules formed as a result of rolling flat atomic layers of graphite (graphenes). CNTs can be single- and multiwalled (consisting of several coaxial cylinders). The inner diameter of nanotubes ranges from 0.4 to several nanometers, and their length, as a rule, does not exceed several tens of micrometers. The aim of this work is to obtain zinc-based CECs modified with CNTs in a pulsed electrolysis mode and to investigate their structure, tribological properties, and corrosion–electrochemical behavior.
The advantage of nonstationary electrolysis modes (in particular, pulsed) is the ability to control a much larger number of parameters of electrodeposition of coatings. The parameters of unsteady modes have a significant effect on the growth dynamics and properties of metal precipitates. The pulse mode promotes the formation of coating
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