Acoustic wave-powered durable icephobic duplex coating design with superior de-icing performance

Piezoelectric thin film-based surface acoustic wave (SAW) de-icing technology has recently emerged as an attractive and energy-efficient alternative with direct applications across multiple industrial sectors. However, the generation of SAWs on piezoelectric thin films, such as ZnO, faces diverse challenges, including its low long-term stability and variable wetting properties upon exposure to UV radiation and other environmental hazards. To overcome these challenges, we propose a bilayer coating design that integrates a diamond-like carbon (DLC) thin film with an atop CFx layer (DLC-CFx). This design is intended to serve as both an anti-icing and a protective coating for ZnO SAW devices built on aluminum substrates, which are specifically selected for critical ice-exposed applications in the aeronautics or wind turbine industries. We demonstrate that, unlike the implementation of single fluorinated polymer layers, such as commercial CYTOP solutions, the DLC-CFx hydrophobic duplex coating effectively protects the ZnO surfaces while maintaining optimal SAW transmission and wave propagation and reducing the fluorine content. The SAW-induced de-icing on these devices is achieved through a highly effective mechanism involving the interfacial ice melting, followed by a rapid ice sliding detachment for both small ice droplets and large ice aggregates. Experiments at laboratory scale and in an icing wind tunnel facility reveal that de-icing involves SAW activation of the interface between the ice and the DLC-CFx bilayer, as well as an effective thermal contribution resulting from the rapid heat transmission through the aluminium substrate. Our studies demonstrate that the highly conformal deposition of DLC-CFx through a room temperature plasma-assisted method ensures reliability and long-term stability of thin-film-based acoustic wave devices in harsh outdoor conditions.