Zinc Composite Layers, Incorporating Polymeric Nano-aggregates: Surface Analysis and Electrochemical Behavior

摘要

This study reports on a comparative investigation of the corrosion behavior of zinc (Zn) and nano-composite zinc (ZnC) galvanic layers in 5% NaCl solution. The metallic matrix of the ZnC layers incorporates nano-sized, stabilized polymeric aggregates, formed from the amphiphilic tri-block co-polymer: poly(2-hydroxyethyl methacrylate) - poly (propylene oxide - poly (2-hydroxyethyl methacrylate) (PHEMA15PPO34PHEMA15). The main objective was to evaluate the electrochemical properties and surface characteristics of both coatings, thus further to investigate if the nano-composite layers will have better corrosion resistance, compared to pure galvanic zinc. The electrochemical behavior, investigated by Impedance spectroscopy (EIS) and Scanning vibrating electrode technique (SVET), supported by surface analysis, using Atomic-force microscopy (AFM) and Scanning electron microscopy (SEM), reveals higher corrosion resistance and consequently better performance of the nano-composite layers, compared to pure galvanic zinc. The mechanism of incorporation of the polymeric nano-aggregates in the coating and their influence on the barrier properties of the composite layers are also briefly discussed.