Evaluation of Structure, Heterogeneities, Thickness and Corrosion Protection of Electrodeposited Sol-Gel Superhydrophobic Coatings

Abstract

The present work evaluated the structure and heterogeneities, surface chemistry, hydrophobicity level, and corrosion protection in a saline environment of electrodeposited sol-gel superhydrophobic coatings on carbon steel, using microscopy techniques, energy dispersive X-ray spectroscopy (EDX), water contact angle measurements, and electrochemical impedance spectroscopy (EIS). Furthermore, the effect of silane precursor concentration on the aforementioned response variables was tested. Regarding the structure, results point out rough deposits composed of two layers with different properties and thicknesses, and preferential deposition on the top area of the carbon steel coupon. Elemental mapping proved the chemical stability of the film in NaCl 3.5%wt., while increasing the amounts of silane precursor up to 40 mmol showed also increased results for water contact angle (157^o), impedance modulus at 0.01 Hz (10⁷ Ohm.cm²), and film thickness (70 µm). However, the addition of greater amounts resulted in miscibility issues in the hydrolysis solution.

Keywords:
Sol-Gel; electrodeposition; superhydrophobicity; heterogeneities; corrosion