Evaluation of synergistic effect of nanozinc/nanoclay additives on the corrosion performance of zinc-rich polyurethane nanocomposite coatings using electrochemical properties and salt spray testing

Abstract

This research work focuses on the synthesis, characterization and processing of polyurethane/zinc/clay nanocomposites to improve the corrosion performance of zinc-rich coatings. Therefore different percentages of montmorillonite clay nanolayers were added to zinc-rich polyurethane nanocomposites. Ultrasonication process was used to prepare polyurethane/nanozinc/nanoclay composites. Then coatings were applied on steel panels with composition of 10wt.% nanozinc and 0.5wt.%, 1wt.%, 1.5wt.%, and 2wt.% nanoclay. TEM was used to analyze the structural characteristics of the samples. The results of the structure analysis revealed the size of nanomaterials. The anticorrosive properties of the nanocomposites were investigated using DC polarization technique, electrochemical impedance spectroscopy (EIS), water absorption and salt spray test. The results of electrochemical tests showed that addition of clay nanolayers improves the corrosion resistance of coatings and the best corrosion performance obtained for the nanocomposite sample with 2wt.% nanoclay. Also, according to the results of the salt spray test, the sample with 2wt.% nanoclay showed the least H2O penetration and exfoliation adjacent to the scratches.