In-situ grown ZnO-nanorods of slippery liquid-injected porous surface coating on Mg alloy with hydrophobic, durable, and anti-corrosion properties

Abstract

In this work, an in-situ self-grown nano-ZnO/epoxy-based slippery lubricant liquid-injected porous surface (SLIPS) coating with a unique bilayer structure is reported to achieve robustness, hydrophobicity, and anti-corrosion properties. Dense epoxy coated ZnO nanoparticles are used as the anti-corrosion barrier layer. Self-grown ZnO nanorods provide a robust micro- and nano-rough porous structure. The lubricant perfluoropolyether (PFPE) is strongly locked into the porous structure via low surface energy material pretreatment and capillary effect. This SLIPS coating has a high water contact angle (WCA) value and has excellent repellency to various liquids. The SLIPS surface maintains a high contact angle of more than 115° even after 20 days of immersion in corrosive solutions and withstand the erosion of corrosive solutions with pH = 3. It also has a very low corrosion current density of 8.97 × 10−12 A/cm2 and the Rct (the charge transfer resistance) of optimum SLIPS remained 1.41 × 108 ohm cm2 after 70 days immersion in 3.5 wt% NaCl solution, which is in the same order of magnitude as the initial value. The SLIPS coating with excellent mechanical stability, super-hydrophobicity, anti-fouling, chemical stability, and long-term corrosion resistance performance possesses tremendous application potential in long-term corrosion protection of Mg alloys.