Study of nano-ZnO improvement of the mechanical properties and corrosion resistance of modified-SiO2/PTFE superhydrophobic nanocomposite coatings by one-step spraying

Abstract

The versatility of superhydrophobic coatings has attracted attention in various fields. However, the unsatisfactory corrosion resistance, poor mechanical robustness, and complex manufacturing process have greatly hindered the application of superhydrophobic coatings. A cheap and simple method for preparing wear-resistant and corrosion-resistant superhydrophobic coatings on steel substrate was described in the article. The 3-methacryloxypropyltrimethoxysilane (KH570) modified silicon dioxide particles were inserted into the stratified interval formed by the coordination of nano-zinc oxide with the carboxyl group in stearic acid. Finally, a strong and compact superhydrophobic coating was prepared by the bonding of polytetrafluoroethylene (PTFE). The results showed that the superhydrophobic coating has a water contact angle (WCA) of 155. 4° ± 1° and a sliding angle (SA) of 1.5° ± 1°. The comprehensive performance and morphological properties of coatings were characterized by scanning electron microscopy, electrochemical testing, self-cleaning tests, mechanical abrasion tests, coating adhesion tests and coating hardness tests. The adhesion of the superhydrophobic coating to the metal substrate is grade 1, which is four levels higher than that obtained before. The coating maintains an excellent superhydrophobic performance after the long-distance wear test and pin-tube jet test. The initial impedance value of the superhydrophobic coating immersed in sodium chloride solution for a short time is 6.87 × 10⁹ Ω. The coating has a strong resistance to corrosive media. The E_corr and i_corr values of the superhydrophobic coating after immersion in salt water for 7 days are −0.227 V and 7.68 × 10⁻¹¹ A cm⁻² respectively. In addition, the corrosion inhibition efficiency of the superhydrophobic coating on the metal substrate is 99.99%. The superhydrophobic coating maintains excellent corrosion resistance in a harsh immersion environment. It can be predicted that the low-cost, wear-resistant and corrosion-resistant superhydrophobic coating prepared by the one-step spraying method can be widely used in various fields to provide surface cleaning and metal corrosion protection.