Preparation and Evaluation of Epoxy-Clay Nanocomposite Coatings for Corrosion Protection

Polymer-clay nanocomposite coatings have attracted much attention because of impressive enhancements of coating properties. In this research, both commercially available and isophoronediamine-modified montmorillonite clays were used to obtain epoxy-clay nanocomposite coatings. These nanocomposite materials with different clay loadings in the form of coatings were applied to cold-rolled steel (CRS).The morphology and structure of the coating compositions were characterized using sedimentation tests of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The corrosion resistance properties of the neat resin and nanocomposite coatings in 3.5% NaCl solution were investigated by electrochemical impedance spectroscopy (EIS) for more than 210 days. After making the measurements, we found advanced protection of nanocomposite samples against corrosion compared with the neat resin. Also, the results showed that the dispersion quality of clay layers into the matrix depended on the structure and modification of clay and the compounding method. Coating compositions containing two or more weight percent of well-dispersed clay resulted in superior corrosion protection. Considering the structure and compounding methods, corrosion protection of both nanocomposite coatings containing amine-modified and commercially available clays was excellent.