Improvement of active/passive anti-corrosion/weathering properties of epoxy-siloxane structure via cloisite 30B/polyaniline inclusion as new hybrid nanocomposite coatings

Abstract

Researches in the corrosion protection field have been led to various mechanisms for protecting metals in harsh media as well as several efficient anti-corrosion materials. For instance, some studies have suggested clay nanolayers as an active barrier filler for coating protected systems and others have figured out polyaniline as an anti-corrosive pigment. However, no study has thoroughly examined these two additives alongside each other and compared their mechanical, anti-corrosion and anti-weathering performances. In this study, two different mechanisms of active barrier and passive behaviors were compared through epoxy-siloxane reinforcement by divergent contents of 1–4 wt% of Cloisite 30B nanoplatelets (CN) and 0.25–1 wt% of polyaniline emeraldine base (PEB) particles. Also, the effect of CN and PEB particles on corrosion, weathering resistances, and mechanical properties of epoxy-siloxane based hybrid nanocomposite matrix was explored as novel effective/potent functional coatings applied on the mild steel substrate. In this regard, the proper dispersion of additives was characterized by XRD, optical microscopy, and HRTEM. Anti-corrosion properties of the system were assessed via EIS and salt spray examinations. According to the significant effect of mechanical properties on the protection and overall performance of coatings, they were studied through Pull-Off, DMTA, and impact tests. Q-UV test, AFM, and color spectroscopy were utilized for analyzing the weathering resistance of samples. Results indicated that 2 wt% CN and 0.75 wt% PEB has the best anti-corrosion performance as well as desirable resistance against destructive atmospheric agents. Overall, in comparison, the CN nanosheets possessed higher anti-corrosion behavior as a potent barrier function, whereas the PEB showed dominant weathering resistance via an impressive passivation feature.