Chitosan coatings ionically cross-linked with ammonium paratungstate as anticorrosive coatings for zinc

Abstract

Chitosan (Chit) coatings deposited on zinc by dip coating technique were impregnated with ammonium paratungstate (PTA) to improve their anticorrosive effect.UV–Vis spectroscopy was used to determine the layer thickness on glass substrates, while PTA accumulation and retention were studied on quartz. The behavior of the native and the PTA loaded chitosan coatings, along with their degradation in time were studied with Raman spectroscopy, EDS, AFM, potentiodynamic polarization and electrochemical impedance spectroscopy techniques.Impregnation has significantly lowered the swelling speed of chitosan, additionally, PTA has been retained in the coatings even after 3 days of exposure to a corrosive environment. The strong ionic cross-linking also improved corrosion inhibition effects (from 29% to 98%) of the chitosan coatings by decreasing the permeability of the layer.The Chit-PTA system can be successfully applied as a short-term anticorrosive coating, removable on demand without damaging the underlying substrate.