Slippery coatings with mechanical robustness and self-replenishing properties as potential application on magnesium alloys

Slippery liquid-infused surfaces (SLISs) have the same development potential and application prospects as superhydrophobic surfaces (SHSs) in the fields of corrosion resistance, anti-icing, anti-fouling and drag reduction. However, the durability of SLISs is still a challenge because of the migrating, evaporating, or leaking of the infused liquids. Herein, we proposed a durable polydimethylsiloxane/silicone oil (PDMS-oil) system with mechanical robustness and self-replenishing property. As a demonstration of potential application, the PDMS-oil coating was applied on the magnesium alloy for multi-functions. A layer of PDMS cross-linking network was first cured on the magnesium alloy surface, and then a certain amount of low viscosity dimethyl silicone oil was diffused into the PDMS layer to form the final SLIS coatings. It is found that 50 wt% of silicone oil content is more suitable for the PDMS-oil based slippery coating on Mg alloy, which can maintain a low ice shear strength of less than 30 kPa after 20 icing/deicing cycles and a lower sliding angle of about 30° after wear cycles (under a normal pressure of 10 kPa). Significantly, the proposed PDMS-oil based slippery coating possesses good corrosion resistance and self-replenishing ability, which can also withstand hot water, ice water, and corrosive solutions (i.e. acid and alkaline aqueous solutions). The Mg alloy with the PDMS-oil based slippery coating can remain intact in a 3.5 wt% NaCl aqueous solution even after 20 days at room temperature. It is believed that the Mg alloys with the proposed PDMS-oil based slippery coatings would have more potential applications even in severe environments.