Fabrication of superhydrophobic micro-nano structure Al2O3-13% TiO2/PTFE coating with anti- fuoling and self-cleaning properties

Abstract

In this study, Al2O3-13% TiO2 coating was deposited on the AISI 316 L stainless steel substrate by a plasma spraying process (APS). Then, a thin layer of Polytetrafluoroethylene (PTFE) emulsion was coated on the created coating. The morphology and chemical analysis of the coating surface were studied with Field Emission Scanning Electron Microscopy (FESEM) and Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR). The water contact angles on the prepared samples were measured by a water contact angle analyzer method. The self-cleaning behavior of the samples was evaluated by an iron oxide powder. The fouling test was performed by simulating the fouling conditions. Electrochemical impedance spectroscopy (EIS) and salt spray test were performed to evaluate the corrosion resistance of the coatings. The results showed that the water contact angle of the Al2O3-13% TiO2 coating surface was 56° and for PTFE modified Al2O3-13% TiO2 coating was 155° The size of the teflon particles in the coating is 200–800 nm. Also, the results of the fouling test showed that after 90 days, no fouling was formed on the surface of the PTFE modified coating. EIS results indicated that the PTFE coating due to its higher capacitance had higher corrosion resistance than Al2O3-TiO2 coating. After salt spray test, the contact angles on the PTFE and Al2O3- TiO2 coatings were 47° and 150°, respectively. Therefore, the modified coating has higher corrosion resistance than Al2O3-13% TiO2 coating.