Superhydrophobic Stearic Acid Deposited by Dip-Coating on AISI 304 Stainless Steel: Electrochemical Behavior in a Saline Solutions

Abstract

A superhydrophobic surface with excellent corrosion resistance was prepared on sandblasted AISI 304 stainless steel by applying stearic acid through dip-coating. Superhydrophobic surfaces have several advantages, such as self-cleaning, anti-icing, anti-adherent, and anti-corrosion. In this work, roughness and superhydrophobic properties were studied by contact angle, optical profilometry, electrochemical impedance spectroscopy, and potentiostatic polarization techniques. The lowest surface wettability was obtained in sandblasted samples (146.2°, due to the roughness change). The stearic acid coating response on sandblasted substrates was acquired by EIS analysis. The sample set with higher corrosion resistance at saline solution during the polarized potentiostat tests was the smoothly coated sandblasted samples. For comparison, corrosion current density of sample without coating was 3.13x10^-7, whilst the coated sample was 1.34x10^-8. Further, the passive current density was 6.02x10^-7 for as-received samples and 2.16x10^-8 for coated samples. The modified surface proved to be effective against corrosion when compared to smooth surfaces.

Keywords:
superhydrophobic coating; stainless steel; corrosion; contact angle; stearic acid