Preparation of Poly(o-ethylaniline)-SiC/Zinc Bilayer Coatings and Study of Its Corrosion Resistance Properties

Abstract

The present work aims to study the differences of structure and corrosion resistance of poly(o-ethylaniline) (POE)-SiC/zinc (Zn) and POE/SiC-Zn bilayer coatings. Herein, POE and POE/SiC composite (PSC) were prepared by emulsion polymerization method, Zinc (Zn) and SiC/Zn composite coatings were prepared by electrodeposited technique. The structures of polymer materials were characterized by Fourier transformation infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), and the electrochemical behavior was studied by cyclic voltammetry (CV) measurement. Subsequently, the polymer materials were spread on the surface of electrodeposited coatings and thus obtained POE-Zn, PSC-Zn and POE-SiC/Zn bilayer coatings. The structures of Zn and SiC/Zn coatings were characterized by FTIR, XRD and energy dispersion spectroscopy (EDS) and the surface morphologies of all coatings were also studied by SEM. The corrosion resistances of the coatings were investigated in 3.5% NaCl solution by Tafel polarization curve and electrochemical impedance spectroscopy (EIS). It was shown that the addition of SiC nanoparticles to Zn matrix significantly changed the microstructure and improved the corrosion resistance. POE-SiC/Zn coating is more protective than PSC-Zn and POE-Zn coatings, with a corrosion rate of 0.021 mm/year and the corrosion protection efficiency up to 98.86%. The excellent corrosion protection of POE-SiC/Zn bilayer coatings was attributed to the fact that inner SiC/Zn coating possess a compact micro/nano surface, which facilitates the good embedding of outer POE coating and thereby eliminates the damage of the residual air in the grooves to outer coating. A conclusion was depicted that the protection is associated with the double barrier effects of outer/inner coatings and the passivation effect of POE. The protection mechanism conferred by POE-SiC/Zn bilayer coatings was also discussed.

Superhydrophobic Surface with Stepwise Multilayered Micro- and Nanostructure and an Investigation of Its Corrosion Resistance

“…The R f value and R c value are able to reveal the corrosion resistance for the modified film (control sample) and the aluminum matrix superhydrophobic surface (STA-PDMS-ZnO sample), respectively. An extra constant phase element (CPE f and CPE c ) is presented in the equivalent circuit because of the dielectric nature on superhydrophobic samples. − It can be seen that the capacitive diameter of superhydrophobic samples is much greater than that of the bare aluminum alloy. The enlarged capacitive loop was related to the entrapment of air by superhydrophobicity, − thus superhydrophobic samples were able to reduce the attack of chlorides and water molecules on bare aluminum alloy when in the corrosive medium.…”

Fabrication of Poly(o/m-Toluidine)–SiC/Zinc Bilayer Coatings and Evaluation of Their Corrosion Resistances

“…Based on that, in order to study the effect of methyl substituent on the structure and corrosion resistance of PANI, we synthesized poly(o/m-toluidine) and applied it to the surface of composite SiC/Zn coating. In our recent investigations [20], we found that the corrosion protection effect of poly(o-ethylaniline) on composite SiC/Zn coating is stronger than that of poly(o-ethylaniline)/SiC composite to pure Zn coating, which indicates that the corrosion resistance of bilayer coating is dependent on the interaction between the inner/outer coating films. Therefore, in order to avoid the anodic oxidation defects of galvanized steel and expand the industrial applications of bilayer coatings, the fabrication procedure of bilayer coatings mainly takes three steps.…”

“…According to our more recent study [20], the SiC/Zn coating can be electrodeposited on the surface of a carbon steel coupon (2 cm × 2 cm). Before the electrodeposition, the carbon steel coupon underwent a series of processes such as polishing, degreasing, pickling, rinsing, and drying.…”