Multi-walled carbon nanotubes – zinc in commercial acrylic sealant as a coating for anticorrosive protection system in metallic building structures

Abstract

Corrosion protection is a matter of primary importance. In this regard, different methods have been explored to improve the protection of vulnerable areas of metallic structures with the aim of maintaining the homogeneous distribution of the protective layer and reducing cracks that allow the entry of corrosive agents. In this study, coatings with Multi-Walled Carbon Nanotubes and Zinc (MWCNTs-Zn), synthesized by the chemical vapour deposition method, in a commercial acrylic sealant were tested to protect welds. The coatings were produced with three different MWCNTs-Zn ratios (80:20; 50:50; 20:80) and applied to welded joints. The tested samples, characterized by SEM and XRD, showed a good dispersion of the MWCNTs tubular structure surrounding the Zn lamellar structure. In addition, the coatings exhibited a particle size range from 29 to 352 nm, which acted as a barrier against the corrosive medium, improving the anticorrosive performance. Electrochemical techniques and accelerated tests at different ages showed that these coatings offer an effective protective barrier. The samples were subjected to an accelerated corrosion test during 336 h, the 50:50 MWNTCs-Zn ratio presented better results than the 80:20 ratio (icorr and Rcorr , ∼50% lower in the cyclic corrosion test and 27% lower in the salt spray test).