Hybrid Zinc Coatings with Improved Corrosion Resistance Based on Chitosan Oligosaccharides

Abstract

In this paper, hybrid coatings based on ZnO dispersion in water soluble chitosan oligosaccharides (COS) as dispersion medium were prepared. The obtaining procedure of anti-corrosion hybrid zinc-based coatings containing COS coated ZnO particles in the metal matrix has been described. The available ZnO particles coated with COS were observed by TEM and thereafter added to the starting electrolyte for electrodeposition of hybrid zinc coatings on low-carbon steel substrates. The newly developed objects were collated with ordinary zinc coatings concerning the peculiarities of the morphology, topography and hydrophilicity of the surface (SEM and AFM analyses, water contact angle measurements), as well as corrosion behavior and electrochemical characteristics (cyclic voltammetry, potentiodynamic polarization curves, polarization resistance measurements). XRD and XPS methods were applied for studying of the crystallographic structure, as well as chemical and phase composition of the newly appeared corrosion products during the corrosion treatment in the test medium. Protective parameters of the coatings were evaluated in chloride environment of 5% NaCl solution. The results showed the effect of the concentration of the COS coated ZnO particles on the crystallographic structure and on the anticorrosion stability of the hybrid coatings.