Enhanced Corrosion Protection Performance by Novel Inhibitor-Loaded Hybrid Sol-Gel Coatings on Mild Steel in 3.5% NaCl Medium

Abstract

The sol-gel methodology has been applied successfully in the synthesis of a novel hybrid coating basedon dimethoxymethyl-n-octadecylsilane precursor. The newly synthesized parent coating was functionalizedfurther with two commercially-available corrosion-inhibitive pigments Moly-white® 101-ED and HfucophosZapp®, applied to mild steel panels, and immersed continuously in 3.5% NaCl electrolytic solution for288 h. The corrosion protection performance of the prepared functional coatings was evaluated usingelectrochemical impedance spectroscopy (EIS) and DC polarization techniques. An enhancement in the barrierproperties has been revealed from the electrochemical characterization data of the hybrid films, in comparisonwith untreated mild steel substrates following long-term immersion in 3.5% NaCl. The corrosion resistanceproperties of the newly developed coatings over mild steel substrates found to be largely dependent onthe type of the loaded inhibitive pigment in which the Moly-white inhibitor has a positive impact on thecorrosion protection performance of the parent coating, while an opposite behavior was observed upon mixingthe base polymeric matrix with the commercially-available Zapp corrosion inhibitor.