Ultrasonic atomization based fabrication of superhydrophobic and corrosion-resistant hydrolyzed MTMS/PVDF coatings

Abstract

A stable self-cleaning superhydrophobic coating with reliable corrosion resistance was coated on the aluminum alloy 6061. A dense polyvinylidene fluoride (PVDF) layer was first coated by the doctor blade method, and hydrolyzed methyltrimethoxysilane (HMTMS) nanospheres were then deposited on top of the PVDF using ultrasonic spray hydrolysis technique. Superhydrophobic coatings with a contact angle (CA) of 167° and a sliding angle of 7 ​± ​1° were obtained. The superhydrophobic coating exhibited self-cleaning behavior. The corrosion resistance of the layers was investigated in a 3.5 ​wt% NaCl aqueous solution using potentiodynamic polarization measurement and electrochemical impedance spectroscopy techniques, indicating the high corrosion resistance of the flat PVDF barrier and the excellent resistance of the superhydrophobic coating. The charge transfer resistance of the bare aluminum substrate measured as 6.572 ​kΩ ​cm² increased to 848.463 ​kΩ ​cm² and 3.411 ​× ​10³ ​kΩ ​cm² with PVDF and HMTMS, respectively. The results showed that a proper superhydrophobic coating with good chemical stability could significantly increase the corrosion resistance of the substrate. We also showed the capability of the novel ultrasonic spray hydrolysis technique in fabricating stable superhydrophobic films for large-scale applications.