A robust superhydrophobic PPS-PTFE/SiO2 composite coating on AZ31 Mg alloy with excellent wear and corrosion resistance properties

Composite coatings consisting of polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE) and 40 nm silicon dioxide (SiO 2 ) nanoparticles (PPS-PTFE/SiO 2 ) with SiO 2 in the range of 0–4 g/l were successfully prepared on AZ31 Mg alloys by a simple spray process. The morphology, composition, water contact angle (WCA), wear behavior and corrosion properties of the composite coatings were measured by using SEM, FT-IR, OCA20, sandpaper abrasion and electrochemical workstation, respectively. Effects of SiO 2 content on the wear behavior and corrosion properties of the coatings were studied. It is found that micro-sized protrusions distribute on the surface of the coatings, and a fibrous-network structure of PTFE arranges on the protrusions. WCAs of the PPS-PTFE/SiO 2 (0–4 g/l) coating are in the range of (152°–145.5°) ± 0.3° and the sliding angles (SAs) are less than 5°. The WCAs of the un-abraded and 10 m-abraded-on-sandpaper PPS-PTFE/SiO 2 (4 g/l) coating are 145.5°±0.3° and 142.5°±0.3°, respectively, implying the PPS-PTFE/SiO 2 coating is a robust superhydrophobic one with good wear resistance. Due to the superhydrophobic characteristics, the PPS-PTFE-based coatings show superior corrosion resistance in 3.5 wt% NaCl solution to pristine AZ31 Mg alloys. Owing to the excellent superhydrophobicity, wear resistance and corrosion resistance properties, the robust PPS-PTFE/SiO 2 coating is regarded to possess great potential to be applied in automobiles and navigation industries in future.